Science topic

Polymerization - Science topic

Chemical reaction in which monomeric components are combined to form POLYMERS (e.g., POLYMETHYLMETHACRYLATE).
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Hi,
I was checking pDNA-Polymer binding affinity in Gel electrophoresis.? After running gel, I noticed complete migration of pDNA as well polymer -pDNA complexes. (Even in higher N/P ratios - 10,20) . I used Agarose 0.6% , 80V , 60 min.
Again, I gradually increased Agarose concertation , 0.8, 1, and 1.2% and voltage 80 to 100 V) - same problem- Complete migration.
Then, I increased pDNA concentration from 10 ng/microliter to 50 ng per microliter. Same issues.
I attached my Gel picture for reference
I performed PicoGreen Assay - it showing good binding affinity, but while running gel , I am not able to see polymer pDNA binding.
Can anyone give some suggestions to troubleshoot this problem.
Thank you
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HI,
Thank you for the response. I included pDNA as control(Lane 2) . If you open the image, I labeled the sample name as Ladder, pDNA and Polyplexes.
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Hi! can anybody suggest on which solvent and conditions can be used to dissolve EVA (Ethylene-vinyl acetate) polymer?
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EVA (Ethylene-vinyl acetate) can be dissolved using organic solvents like tetrahydrofuran and dichloromethane, often aided by ultrasonic irradiation for complete dissolution.
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I am working with PS-DVB microsphere and have observed a luminescence in this wavelength range. Could this be related to impurities, structural defects, or specific effects associated with DVB crosslinking? I would appreciate any references or insights.
Link to the procedure of synthesized microsphere:
Choi, J., Kwak, S.-Y., Kang, S., Lee, S.-S., Park, M., Lim, S., ...Hong, S. I. (2002). Synthesis of highly crosslinked monodisperse polymer particles: Effect of reaction parameters on the size and size distribution. J. Polym. Sci., Part A: Polym. Chem., 40(23), 4368–4377. doi: 10.1002/pola.10514
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Polystyrene would not be expected to show fluorescence at 510. Polystyrene shows two emissions: monomer emission at 285 nm and excimer at 332 nm. The relative ratios are concentration dependent.
We explored this thoroughly in our 2007 paper
However, the prep you cite also includes polyvinylpyrrolidone - which is known to have some emission at wavelengths as high as 510, although the maximum is at 375 nm.
I recommend running an excitation spectrum from 200 to 480 or so with detection at 510 - this will give you the absorbance spectrum of the emitting species.
Because fluorescence is very sensitive, it is very easy to detect fluorescence of trace impurities.
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During electrospinning of keratin with very low concentration of polymer,protrusions have been obtained... shown in the figure
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This could be due to the low concentration of polymer, which does not maintain the formation of a proper Taylor cone. The low concentration may not attain the suitable viscosity to form a fiber.
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I've seen a research article that tested a polymer sandwich structure in 3-point bending according to ASTM C393. Their testing parameters included a 100 mm span length, a 2.0 mm/min loading rate, and specimen dimensions of 150 mm length, 18 mm thickness, and 32 mm width. Can I use these same dimensions for my own samples?. Or is there any rule to find the specimen dimensions?
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The dimensions of the specimen indicated are ok. Please see the peak load for failure/flexure takes place within the capacity of the UTM.
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I am conducting free radical polymerization with the following conditions:
  • Initiator: AIBN
  • Solvent: DMF
  • Monomer: MMA (5 g)
  • Initiator Amount: AIBN (0.04 g)
  • Solvent Volume: DMF (20 mL)
  • Reaction Temperature: 70°C
  • Reaction Time: 6 hours
  • Atmosphere: Nitrogen (N₂)
  • Setup: Condenser used
However, instead of obtaining a powdered polymer, I am getting a gel-like or highly viscous polymer. Please suggest what could be the reason.
Thank you
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You could try bulk polymerization, by not using a solvent. You just need to add the radical initiator to the MMA and apply temperature.
It usually yields higher molar masses. On the other hand, it also yields greater polydispersity.
However, you need to be very careful in controlling your reaction, especially temperature, or else you could come across the gel effect, when molar mass grows very fast and limitless.
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Can a acrylic polymer filled with high entropy oxide have high conductivity and high permittivity in the same time at the same filler concentration? Can you provide me with some references?
Thank you
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Yes, it is theoretically and practically possible to have high permittivity and high conductivity simultaneously in a material. However, it's a complex relationship and depends heavily on the specific material and frequency of operation. Here's a breakdown of why and how:
Why it's possible:
• Different Mechanisms: Permittivity (ε) and conductivity (σ) are related to the material's response to an electric field, but they arise from different physical mechanisms:
• Permittivity: Represents the ability of a material to store electrical energy when an electric field is applied. It's related to the polarization of the material, which can be due to electronic, ionic, or orientational polarization.
• Conductivity: Represents the ability of a material to conduct electric current. It's related to the movement of free charge carriers (electrons or ions) in response to an electric field.
• Material Structure and Composition: Certain materials possess structures or compositions that allow for both high polarization and high free charge carrier concentration.
How it's achieved:
• Doped Semiconductors: Semiconductors with high doping concentrations can exhibit both high permittivity and high conductivity. The doping increases the number of free charge carriers (conductivity), while the semiconductor material itself can have a relatively high intrinsic permittivity. However, this often comes with a trade-off as very high doping can sometimes reduce the permittivity.
• Perovskite Materials: Some perovskite materials exhibit ferroelectric behavior (high permittivity) and, with appropriate doping or defects, can also be made conductive.
• Composites: Combining a high-permittivity material with a conductive material in a composite structure can achieve the desired properties. The challenge is to engineer the composite to ensure good connectivity and maintain the desired permittivity.
• Conductive Polymers: While most polymers are insulators, some polymers can be made conductive through doping or by incorporating conductive fillers. These conductive polymers can also exhibit a relatively high permittivity, especially at lower frequencies.
• Metamaterials: Engineered materials with artificial structures can be designed to exhibit both high permittivity and high conductivity at specific frequencies. However, metamaterials are often lossy and can be challenging to fabricate.
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Hello,
I would like to inquire if you are aware of any computational tools for predicting drug release from polymeric nanoparticles. I do not have experience in this field and recently attempted to use a tool from nanoHUB, which is free to access. However, the numerous options available have left me confused about which one I should choose.
Thank you in advance!
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For predicting drug release from polymeric nanoparticles, you can explore tools like:
  1. nanoHUB: Provides multiple tools; focus on "Polymer Nanoparticles" or "Drug Delivery Models."
  2. Comsol Multiphysics: For simulating the release kinetics.
  3. Molecular Dynamics Simulations: Tools like GROMACS and AMBER can model drug release using simulations.
All of which can we easily done at mdsim360.com, a new platform that lets you run MD simulations entirely online without local installation.
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Recently, I've started to design my experiments and I need to use a tool as a coupon holder for some corrosion tests. I found papers that used PEEK as their coupon holder due to its minimum reaction with corrosive microorganisms. This substance is very expensive and I am looking for a cheaper alternative polymer with the properties of PEEK (It should not be antibacterial).
I would be really grateful if someone could help me with this.
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As mentioned above, Fluorinated polymers are good candidates. You may look at fluorosilicones, If you look at the cheapest material, you may check polyethylene which does not easily degrade. However, it will get fouled. Another way to reduce the cost is to use glass fiber composite of PU, or other material as mentioned above.
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I am conducting molecular simulations to study the interaction between RNA and a polymer. However, during the simulation process using GROMACS, multiple errors arise, hindering the progress of the simulation. I am seeking guidance to troubleshoot and resolve these issues effectively."
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To troubleshoot RNA-polymer simulations in GROMACS:
  1. Check topology and parameter compatibility: Ensure proper force fields for RNA and the polymer (e.g., CHARMM for RNA).
  2. Minimize energy: Perform energy minimization to avoid steric clashes.
  3. Review input files: Double-check the PDB, topology, and simulation settings for errors.
  4. Use proper restraints: Apply constraints to stabilize the system (e.g., for the polymer backbone).
  5. Check simulation box: Ensure the box is appropriately sized for both RNA and polymer.
Fix errors step-by-step and review GROMACS logs for specific issues.
all of which can we easily done at mdsim360.com, a new platform that lets you run MD simulations entirely online without local installation.
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I have a question of a solution to get better posibilities of copolymerization of styrene with eg. 5-bromo-1-pentene using radical initiator.
I started from analysing the system when: styrene and 5-bromo-1-pentene added dropwise to AIBN in toluene at 70C with argon bubbling for 4h then left 16 hours. I use 5:1 solvent to monomers ratio. And got about 46% alkyl to styrene with low yield - 7.5%.
Looking for a solution to catalyse this to better yield like 30% or more. I will also test normal condition in solution polymerization 1:1 to solvent (not added dropwise) to see difference.
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chlorobenzene would be my choice - DMF can have degradation impurities (dimethylamine, water, etc) that might interfere
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Adding copper acetate with KI in polyamide during polymerization, there is always some copper plating out and deposits on the surface of the polymerization device. There is a reduction reaction Cu2+ to copper metal during the polymerization. How does this reaction happen? What is the reaction equation?
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Copper plating out in polyamide during polymerization occurs due to the reduction of Cu²⁺ ions to metallic copper (Cu⁰), represented by the reaction: Cu2+ + 2e- ---------Cu.
This reduction can be influenced by factors such as pH, temperature, and the presence of reducing agents.
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Considering that I want the ZIF-8 nanoparticles to be placed inside/ on the fibers (which are electrospining ) and have a slow release when placed on the wound, what is the best way to add the nanoparticles to the polymer solution. The solvent is Hfip test.
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To disperse ZIF-8 nanoparticles in HFIP for incorporation into a polymer electrospinning solution, first functionalize the nanoparticles and create a stable suspension using sonication. Gradually mix this suspension into the polymer solution while adjusting electrospinning parameters to ensure uniform distribution and effective fiber formation.
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I am looking for ways to increase the average molecular weight of expanded polystyrene (EPS) produced through a Free Radical Suspension Polymerization process. Currently, we use a two-stage initiation system consisting of dibenzoyl peroxide (BPO) as the primary initiator and tert-butyl peroxy-2-ethylhexyl carbonate as the secondary initiator to control residual monomer. While reducing the BPO concentration has led to an increase in molecular weight, further reductions are constrained due to process limitations. Our production process is conducted in 50-ton reactors, and we are exploring alternative approaches without significantly altering the overall process parameters. Specifically, we are limited by the reactor's pressure limit of 12 bar, preventing us from significantly increasing the reaction temperature, and by production rate constraints that limit the available reaction time.
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Для увеличения молекулярной массы растворите в мономере полимер перед полимеризацией и за счет гель-эффекта увеличится молекулярная масса. Подробности в моей диссерации.
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A polymeric nanocarrier has been established and to check it's entrapment efficiency 8 drugs having anticancer properties have been encapsulated in shell of nanocarrier. The question is why do such experiments are done to try and check making 8 variations of nanocarrier. Is it good to have drug entrapment efficiency of above 80% for all the drugs ?
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Creating eight variations of a polymeric nanocarrier allows for exploring structure-function relationships and optimizing drug delivery for different anticancer drugs. Achieving over 80% entrapment efficiency is beneficial but must be balanced with release kinetics and biocompatibility for effective therapeutic outcomes.
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The objective of this study is to explore the relationship between active oxygen content and the performance of peroxide-based radical initiators in polymerization processes. By varying the active oxygen content, we aim to determine its influence on key polymerization parameters such as initiation rate, decomposition rate, and molecular weight distribution of the resulting polymer.
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Hi, oxygen inhibits polymerization by quenching the excited states of the initiator. This is usually an undesired effect naturally present due to atmospheric oxygen dissolved in the liquid resin but could be also done intentionally in some specific applications (e.g., in nanofabrication).
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the app must be free
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Free apps like Nickzom Calculator and Quizgecko can help you calculate the degree of polymerization (DP) of pyrrole by inputting relevant molecular weights. These tools simplify the process and provide quick results for your calculations.
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Chemical EOR
1. Despite the efficacy of Surfactant Flooding (which essentially improves the pore-scale displacement efficiency by reducing oil-water IFT any by modifying rock wettability), to what extent, the economic feasibility of ‘Free Surfactant Injection’ during a typical Chemical EOR – could positively be addressed - through the utilization of ‘Surfactant Carriers’, towards mitigating extensive losses through adsorption or precipitation on the rock surfaces?
2. Feasible to deduce ‘A Time Dependent Chemical Structure’ of Polymerswhich could possibly act as both ‘Wettability Modifiers’ as well as ‘Surfactant Carriers’, in addition to its conventional expectation on enhancing the volumetric sweep efficiency by reducing the oil-brine mobility ratio through amplified viscosity?
Could ‘polymeric surfactants’ “simultaneously” (a) enhance viscosity in the aqueous medium; (b) reduce IFT; as well as (c) modify rock wettability?
If so, then, the conventional drawbacks including (a) reservoir and well damage; and (b) reduced viscosity due to polymer solution adsorption and shear forces in oil reservoirs (particularly associated with HPHT and High-Saline Reservoirs with relatively heavier oils) – could be gotten rid-off?
3. Since, HPAM’s (which is the prevalent synthetic polymer in EOR flooding) viscosifying potential gets diminished under the presence of high-saline brine, and also, due to HPAM’s susceptibility to thermal and mechanical degradation impacts the longevity of the polymer flooding, can the application either Biopolymers or HPAM Derivatives (amphoteric hyper-branched polymer derivatives) (cellulose, chitosan & galactomannan-guar) could really enhance EOR system stability?
Suresh Kumar Govindarajan, Professor [HAG]
IIT Madras, 16-Dec-2024
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Dear Suresh Kumar Govindarajan, the matter of feasibility of chemical enhanced oil recovery was bypassed decades ago, now it is more focusing improvements and performance. The economic aspect is related more to the residual oil in place, after primary and secondary recoveries. I worked on this topic two decades ago, using partially hydrolyzed polyacrylamide, it is a general purpose polymer with regard to EOR, however sulfonated polyacrylamides are more recommended whenever the problems of adsorption arise. Prof. Charles McCormick work group at the University of Southern Mississippi did a broad and systematic research on major types of polyacrylamides in this area. Following are more recent papers on both surfactant and polymer EOR. My Regards
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My polymer solution is hydrophobic in nature.
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Hydrophobic semipermeable membranes for water are usually made from pvdf-co-hfp. If we consider the microporous pvdf-co-hfp membrane with water as a dispersed system, then the dispersed medium will be water, and the dispersed phase will be pvdf-co-hfp.
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Hello every one,
I have seen somewhere that there is a critical size for ceramic additive particles (specifically BG) for making composite with semicrystalline polymer (specifically PCL). Above that size, the polymer's crystallinity increases and below that size, the polymer's crystallinity decreases. Is there any reference describing or proving this phenomenon?
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Dear Majid Sohrabian, not only size that affect the crystallization kinetics, also shape and concentration (sometimes refered as saturation):
The fourth parameter include any imposed work/stress on the system: flow, mixing, pressure.
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onoe
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Self degradable polyolefins
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What is the purpose of adding from quantum-dot-doped polymer nanowires to silver nanowires?
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  • Quantum dots (QDs): Provide strong and tunable photoluminescence due to their size-dependent bandgap. This feature is useful for applications like light-emitting diodes (LEDs) and lasers.
  • Polymer nanowires (PNWs): Serve as a flexible and stable host matrix for the QDs, helping to maintain their optical properties and improve their spatial distribution.
  • Silver nanowires (Ag NWs): Act as plasmonic materials that can enhance light-matter interactions through surface plasmon resonance, increasing the emission efficiency and brightness of the QDs.
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I have tried the proton NMR of Dendritic PEI and have conjugated it to other polymer via amidation. So now I have to evaluate the conjugation degree using NMR.The software I use is NMR 1D.
How will we evaluate the conjugation degree in such a case and how to integrate the peaks of PEI to that of the polymer in the conjugated system.
I would really use some help if I could get it as I am struck in this for more than 10 days.
Thank you in advance
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Abdelhak Maghchiche Thank you for th response.
I tried to do the same, but is struct where you would have to give the reference no for the protons in DPI. Since I couldnt find that, is it correct to give the SA referencce peak as 4 (no of protons in SA) and based on that, evalauate the conjugation degree with the integral of DPI?
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I am currently trying to produce a dispersion of a biopolymer in water. For this, I first dissolve the polymer in an organic solvent that I then add to an aqueous phase with surfactants (up to 2%). During the homogenization, the solution seems homogeneous but upon evaporation under magnetic agitation, clumps tend to form. I have tried PVA, and Tween 80 at different concentration but similar results tend to happen.
Any suggestions on how to prevent this?
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Thank you for you answer.
I am trying to prevent precipitation or at least slow down this process and would like to keep the particles in suspension as long as possible.
Apologies if the description was not clear enough
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There are Magnesium-based vanadium inhibitors on the market with low viscosities. How are they produced? specifically 28% Mg-containing ones (which are referred as polymerized Mgs) with such high velocity and low viscosity? How can I know about the ingredients and production route of the process?
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Thanks for your reply. Are there any references that can help me find out how such a viscosity can be attained?
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Normally this model is mainly used for electronic product.
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надо смотреть чем модели, которые Вы используете и модель Журкова отличаются друг от друга, но думаю в том и другом случае подход общий определение энергетического барьера реализации процесса
с уважением
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Hallo friends
I have gone through a patent CN101875004A the inventor had attached iminodiacetonitrile to a chloromethlated polymer bead and described chelating ion exchange resin contain the copolymer of the styrene-divinylbenzene of formula (I) and formula (II)
Can any body help me mechanism of the proposed structure. The nitrogen of imino group of diacetonitrile is rearranged to convert NH2C[CH2-C(NH2)(NOH)]2 attached to benzene group of polymer.
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Dear Balakrushna Padhi, please find the reaction path in page 2 of the following free access Chinese paper. My Regards
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can transmittance of uv /vis spectra changes for the same polymer EVA when change faces?
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Dear all, yes and various parameters may contribute to that, such as chains orientation, crystallinity, thermal phase heterogeneity (due to nonuniform cooling down), air bubbles, stress history, and possibly others. My Regards
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I have a doubt from the conceptual point of view, I have seen that none of the flow equations take into account the temperature.
I have analyzed the subject and I have seen that the temperature increase helps to lower the energy consumption of the equipment, but as for the flow maintaining the same RPM of the screw, I have seen that it affects the flow by pressure, but this is compensated by the flow in the extruder head. So the flow rate should not change, at least in theory with the equations.
Am I right or am I missing something?
Thank you very much.
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Your observation is astute. While many flow equations for polymer extrusion don't explicitly include temperature as a variable, its influence is significant and indirectly accounted for in several ways:
1. Viscosity:
  • Temperature-dependent viscosity: The most direct effect of temperature is on the viscosity of the polymer. Higher temperatures reduce viscosity, making the polymer flow more easily.
  • Indirect inclusion in flow equations: While viscosity might not appear explicitly in some equations, it's often a key parameter that influences the flow rate and pressure.
2. Pressure Compensation:
  • Extruder head flow: As you correctly noted, an increase in temperature can lead to a slight increase in pressure due to the reduced viscosity. However, the extruder head is designed to compensate for this by adjusting its flow rate.
  • Dynamic equilibrium: The system reaches a new equilibrium where the increased pressure from the extruder is balanced by the increased flow rate through the head.
3. Screw RPM and Flow Rate:
  • Constant RPM: While maintaining a constant screw RPM generally results in a constant flow rate, temperature can influence the specific characteristics of the flow.
  • Flow profile: The flow profile within the extruder can change due to temperature-induced viscosity variations, potentially affecting factors like mixing and distribution of additives.
4. Energy Consumption:
  • Reduced power consumption: The primary reason for operating at higher temperatures is to reduce the power consumption of the extruder. Lower viscosity means less energy is required to overcome the resistance to flow.
In essence, while temperature isn't explicitly included in many flow equations, its impact is significant and is accounted for indirectly through factors like viscosity, pressure compensation, and flow profile.
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Without changing catalyst (ZN)
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It can be done in the presence of unchanged catalyst
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Dear RG community,
I am looking to use magnetic colloids which are to be further dispersed in a polymer. To avoid agglomeration, I want to functionalize them using Oelic acid. I would appreciate if someone can point towards the exact procedure or a correct way of doing so. Also what purity grade oelic acid one needs to use (technical, culture, analytical etc.)
Thank you in advance
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The functionalization of a solid particle relies basically on the ability of the surface of the particle and the chemical you are aiming to functionalize with, to react together, with the aim of bonding, in your case, the oleic acid to the colloid. The way of doing it will depend specifically on that basically: on the chemistry that will be involved to link the acid to the surface of the particle. Since the oleic acid is exactly that, an acid, a way would be to explore a little bit the chemistry of the acid groups (how do they react, what other groups are needed, etc.). Also, knowing a bit more about the surface chemical groups of your particles would also be beneficial.
Hope it helps!
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we are tried all different concentrations of polymer (Polysulfone) and solvents (NMP & DMF) to synthesis FO membrane. but unfortunately every time polymer penetration occurs across the fabric that results in poor water flux in FO testing.
kindly guide a way through which we can avoid penetration of solvent across the support fabric.
thank you
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First of all, sorry for late response.
In our work, we applied different types of polymeric hydrogels, and we did not noticed any penetration of the particles.
According to our experimental work and our readings, this issue does not exist in the application of hydrogels as draw agents because it is a solid dry material, which swells with water without dissolution.
The phenomenon of reverse diffusion of solutes occurs when solutions are applied as draw agents, and it is called reverse solute flux. This issue is widely discussed in previous studies.
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The mainstream development direction of polymer materials in the future ?
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Top 10 Polymer Industry Trends (2025)
  1. Biopolymers
  2. Recyclability
  3. Smart Composites
  4. Nanopolymers
  5. 3D Printing
  6. Novel Specialty Additives
  7. Advanced Thermoplastics
  8. Conductive Polymers
  9. Lightweighting
  10. Material Simulations
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Please briefly introduce the principle and examples, thank you!
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It depends on the nature of the polymer:
Some examples of biomedical polymers include:
  • Polycaprolactone (PCL)A commonly used polymer for biomedical applications due to its biocompatibility and biodegradability.
  • Poly(Lactide-co-Glycolide) (PLGA)A biodegradable polymer that's commonly used in biomedical devices because it can be engineered to control drug release.
  • PolyanhydridesA biodegradable polymer that's used in biomedical applications like tissue scaffolds, implant coatings, and drug delivery.
  • PolyglycolideA highly crystalline polymer that was one of the first biodegradable synthetic polymers investigated for biomedical applications.
  • Polyhydroxyalkanoates (PHAs)Also known as bacterial polyesters, these polymers are used to fabricate biomedical products like sutures and hernia meshes.
  • CollagenA preferred biopolymer for biomedical applications due to its biocompatibility, weak antigenicity, and versatility.
  • Poly(propylene fumarate) (PPF)A high-strength polymeric biomaterial that can be crosslinked through the unsaturated bonds in its backbone.
  • PolyestersMany polyesters have monomers produced from renewable resources and are biodegradable.
Therefore copolymerization or blends could be an option
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The mainstream development direction of polymer materials in the future ?
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There are several trends. The first is to make it conductive. Less weight
( polymer + graphene or GO)
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The mainstream development direction of polymer materials in the future ?
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Since the "polymers" field is very wide, it is hard to see if there is only one mainstream regarding their development in the future. After reading a bit, now the main trend is to find some biobased new polymers (or modify the ones that we already produce), in order to make them more friendly with the environment. Normally, this is addressed by changing their chemical composition so they can be degraded easily, or some natural options (such as cellulose, or lignin) are being explored.
Another mainstream going around is the exploration of novel polymers with enhanced properties (such as mechanical, flame resistance, electrically conductive, etc), in order to enhance the available options. There is always new raw materials or chemistries employed for the development of novel materials in this aspect. And also, the utilization of nanoadditives (such as metal nanoparticles) are being explored in order to obtain polymeric composites.
Finally, lots of studies appeared in the last couple of years regarding the 3D printing (additive manufacturing) of polymeric materials. Some widely-known polymers are easy to 3D print, but some of them not (specially thermosets), so a lot of developments are being carried out to address this issue.
Hope this gives some insights on what you can search on the web!
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I want to simulate polymer in water for that I have confusion in reduce units according my understanding of reduce units if we perform simulation in reduce units means we are make a generalize model because we set sigma , Ellison, mass and other bonding parameters equal to one means we are simulating not real model.
It's like we are doing simulation of ball and spring model.
My confusion is regarding parameter that is equal to one or not for all atoms?
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Your understanding of reduced units in molecular dynamics simulations is on the right track. Reduced units are a way to scale the physical properties of a system so that certain parameters are set to unity, which can simplify calculations and make the simulation more general. Here’s a clearer explanation of reduced units and how they apply to your polymer in water simulation:
Reduced Units:
In reduced units, the following parameters are often set to 1:
  • Length (σ): The length unit is typically set to the size of a particle, which could be the van der Waals radius or another relevant length scale.
  • Energy (ε): The energy unit is often set to the strength of the pairwise Lennard-Jones interaction between particles.
  • Mass (m): The mass unit is set to the mass of a particle in the system.
These units are defined relative to the system you are studying. For example, in a Lennard-Jones fluid, σ might be the distance at which the interparticle potential is zero, and ε might be the depth of the potential well.
Are All Parameters Equal to One?
No, not all parameters are equal to one. Only the base units (length, energy, and mass) are set to one. Other parameters, such as bond lengths, angles, charges, and force constants, are scaled relative to these base units. Here’s how it works for your polymer in water system:
  • Bond lengths and angles: These are scaled relative to the length unit (σ). For example, if a bond length in your polymer is 0.2 nm, and σ is defined as 0.1 nm, then the bond length in reduced units would be 2σ.
  • Charges: These are scaled relative to the square root of the energy unit (ε) divided by the length unit (σ). This ensures that the electrostatic interaction energy has the correct dimensions.
  • Force constants: For bonded interactions like harmonic bonds and angles, the force constants are scaled relative to the energy unit (ε) and the length or angle unit.
Simulating a Real Model:
When you perform a simulation in reduced units, you are still simulating a real model. The advantage is that the simulation becomes more general and can be applied to a wide range of systems with similar interactions. The parameters you use (like σ, ε, and m) are chosen to reflect the physical properties of the actual system you are studying.
Polymer in Water:
For a polymer in water, you would typically define your reduced units based on the properties of the solvent (water) and the polymer. For example:
  • Length (σ): Could be set to the oxygen-oxygen van der Waals distance in water.
  • Energy (ε): Could be set to the strength of the Lennard-Jones interaction between water molecules.
  • Mass (m): Could be set to the mass of a water molecule.
Then, the polymer’s properties would be scaled accordingly. This does not mean you are simulating a ball and spring model; rather, it’s a way to abstract the physical properties to a set of units that makes the simulation more manageable and computationally efficient.
In summary, using reduced units does not mean you are simulating a non-real model. It is a way to standardize the system so that the simulation can be applied broadly while still reflecting the physical properties of the real system. The choice of what parameters to set to one and how to scale the others depends on the specifics of the system you are simulating.
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Is there a fundamental theory of polymer fibers and nanofibers?
I work with polymer fibers and I am interested in whether there is a fundamental theory to describe them. Suppose fibers are composed of an amorphous rather than crystalline polymer. If they are very thin, they will be unstable for two reasons. Firstly, they have a large free surface area and hence high surface energy. Secondly they are usually composed of highly oriented polymer molecules, which are entropy depleted and tend to adopt a Gaussian coil conformation. Despite the effect of these two factors, nanofibers made of amorphous polymers can be stable in some cases.
Are there theories that estimate the limits of their stability (taking into account the flexibility of polymers and the interaction energy between links)? Are such theories applicable to partially crystalline polymers? I am 100% sure that these theories exist, could you please help me to find them?
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Dear Dmitry Bagrov, please have a look at the following book and the attached file. My Regards
Xiangwu Zhang
Fundamentals of Fiber Science
ISBN-13: 978-1605951195, ISBN-10: 9781605951195
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Currently I am conducting research on the manufacture of anion exchange membrane fuel cells with QPVA:PDDA modified alumina nanoparticles. However, when homogenizing the polymer with alumina nanoparticles with an ultrasonic homogenizer with the JOANLAB brand type MHZ-01 and the huxi brand type HR-6B, the dope solution always produces foam. How to prevent the dope solution from becoming foam when homogenized?
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Check the pH of your solution. It should be acidic due to the hydrolysis of aluminum oxide. Add a little alkali to shift the equilibrium during hydrolysis.
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Ethyl cellulose (EC) polymer is commonly used for preparation of graphene based ink to modulate ink viscosity and film forming ability. The question is how EC reacts with the pristine Graphene not (GO)? Does it form a composite material with chemical bonds or it is just physiosorbtion through hydrophobic interaction ?
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Ethyl cellulose (EC) interacts with pristine graphene through physical adsorption and hydrophobic interactions, rather than forming chemical bonds. The adsorbed EC polymer chains act as a dispersant, stabilizer, and binder, enabling the formation of high-quality graphene inks and films with enhanced charge transport properties.
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1) I don't want to add any other polymer apart from collagen.
2) Suggest me any good cross linker reagent.
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不同类型的胶原,其分子量、二级结构是不同的,建议选用分子量较大的胶原;
交联一般选择EDC/NHS;
成型方法对于材料的力学强度也有非常大的影响,建议选用热压成型的方法。
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Actually i want to know if i have grafted one biopolymer to another derivatized biopolymer and then reinforced metal nanoparticles into it , then what factors should be remind to draw a chemical reaction for this ?
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Dear Sakshi Saini, in your case structure prediction is meaningless, since both the main chain polymer and the grafts will retain their basic structure, and the only change will occur at the attachment points. NMR and other spectroscopic techniques will give the percentage and the distribution of grafts and the newly formed bonds/group. Mass spectroscopy also justify the success of grafting. For the NPs it depends on the mode of modification, is it simple adsorption or direct chamical attachment. More details are necessary to give further suggestions. My Regards
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I am conducting a 2% agarose gel electrophoresis to analyze polymeric nanoparticle encapsulation of Cas9 RNP. My sample set has a charge range from 0 to +10 mV, and I am observing that the more positively charged samples exhibit significant backward migration off the gel. While my gRNA and Cas9 RNP controls show excellent separation with clear, distinct bands, I encounter issues after adding the polymeric nanoparticles for encapsulation. In these cases, I see no defined bands—only backward streaking. I am seeking advice on how to prevent this backward migration or improve band visibility and resolution. Any suggestions would be greatly appreciated. Thank you!
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1. Purpose: Visualize RNA encapsulation within polymeric nanoparticles
2. Anticipated results: Dark banding within the wells; I believe nanoparticles should be too large to migrate in the well
3. TAT is on the surface for electrostatic interactions with RNA; varying amounts of TAT lead to a range of charges. Charges are with RNA
4. We have characterized size (~150 nm) and used TEM but not stability
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如何开发具有特定功能的高分子材料?
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Dear all, specific functions are the results of specific polymer structure. Usually, polymers features are governed by the relationship structure-to-properties. So if specific properties are desired, their must be a screening window of the (co)polymers candidates, and vice versa. My Regards
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Hi
I am dealing with polymer hardness measurement methods. I am familiar with Shore A and Shore D. It is well reported on websites. However, in the case of Shore Micro and Shore A, I cannot see any quantitative or qualitative correlation. It looks like Shore Micro is used for thin, delicate polymer films. Can anybody help me with this? Any hint? Any paper? Any manual?
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How can I pick up the microplastic particle when doing FTIR-ATR? Beacuse I can not directly place my filter paper under ATR.
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Gerry Gonzalez Thank you so much.
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I've got several samples of the same polymer and have reacted them with different plasticisers. On the NMR of all the samples but one, the peaks that I expect to be present in everything are roughly the same width, however for one of the samples, these very same peaks are significantly wider. Is there any reason behind this?
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Yes, if the peak is related to a hydrogen bond. Then you have more hydrogen bonds. Again, not the width, but the area under the peak.
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In a vat polymerization 3D printing, what is the amount of energy required for curing commercial resins? Manufacturers or suppliers usually specify wavelength but not the intensity. Any reasons for this?
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Attached is a free access paper on modelling photocuring and the equations relating the different parameters.
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Hi, I have made a binder polymer resin for uv curing of ink. The viscosity of binder polymer is between 700 to 1300 cps. Basically I disperse the inorganic pigments in the binder polymer along with UV initiator and HDI as an adhesion promotor. The ink takes long time typically 15-30 minutes to cure on Polypropylene surface.
I am looking for some methods to modify HDI with acrylates or methacrylates to make the curing process faster. which chemical methods are useful to modify HDI for faster UV curing on plastic surface.
Any suggestions will be appreciated, Thanks in advance.
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Good evening or good morning, depending on your time! I would like to know the effect of polymer balls on self-compacting concrete. I hope someone can send me a thesis or dissertation on this topic. What are the advantages and disadvantages?
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@Good evening,Abdelhak Maghchiche
Thank you very .very .very much Thank you for the answer....I hope you can help me by sending ang find a thesis, book, or research paper on the effect of polymer balls affect on som properties of self-compacting concrete which exposed to fire flame?
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I have different polymer solutions and I hypothesize that water molecules are retained based on the water-polymer interactions, so the amount of free water is less to intercat with drug tablet.
To validate I tried to find the water evaporation rate from each polymer solution from TGA.
But I see variation due to its high dependence in initial mass.
So now I think to find the Activation energy of water evaporation process. want to know whetehr this is correct, or whetehr there are better ways to prove my hypothesis. May be DSC?
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Michael Sannemo Thank you for your answer
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It is hard to find a vendor that sells this polymer with mole weight larger than 2000. Is it because the difficulty of polymerization?
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Dear Yifan Zhang, high MW are named polyethylene oxides (PEO) instead of PEG. So search for PEO with the targeted MW, you will find even higher MWs than those you need. Polymerization is not so hard or difficult as you may think. My Regards
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I am planning to use a polymer containing branched/linear PEI of 25K with certain size of DNA (E.g. 4Kb). In order to go ahead with experiments I wish to use various N/P ratios. If anyone can help me with calculation for how to caculate the number of Nitrogen and number of Phosphates in my system.
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The N:P. ratio refers here to the ratio of fixed nitrogen (i.e. excluding N2) to phosphate. Fixed nitrogen refers to the sum of nitrate (NO3), nitrite (NO2) and ammonium (NH4). It excludes the always plentiful N2.
The critical N : P ratio is calculated as the ratio between [N] in N-limited plants (grown at Popt) and [P] in P-limited plants (grown at Nopt) that exhibit the same growth rate (treatments to combine are shown by black symbols for r2 and r4).Sep 20, 2004
What is your N/P ratio? - Reef2Reef
📷
https://www.reef2reef.com › threads › what-is-your-n-p...
Jul 1, 2023 — Which N/P ratio most closely resembles your N/P ratio? · High nitrates/high phosphates (N/P ~ 22:1) · Low nitrates/low phosphates (N/P ~ 117:1).
We calculated the positive to negative ratio (P/N) by dividing the average optical density for each sample (P) by the average of the negative controls run on the same plate (N) as the sample This has been described in more detail elsewhere [7, 16] .
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How can I determine a good adhesion strength range for coatings on polymer surfaces, such as DLC on polymer substrates? Is there a specific threshold for adhesion strength (from T-peel tests) above which it is considered adequate, particularly when the coating needs to function as part of a frictional pair?
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Amal Thomas To determine the adhesion, Pull of test can be done to determine it, there several range of devices available in marker ELCO METER 106 is on of them, you can refer this standards which is relavent to the subeject ISO 4624 or ASTM D4541.
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is there any other way to heat a polymer evenly other than oil bath if so what are those and how to use it
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You can use any a Pot gradually increasing the temperature with continues mechanical stirring .while in industrial it can be used injection machine or extruder .
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To find an ideal solvent for electrospinning of carboxymethyl chitosan I searched through many articles but most of them included addition of some polymers such as PVA or PEO to the solution (except one by Sohofi et. al 2014). I tried dissolving carboxymethyl chitosan into aqueous solutions including acetic acid, Dimethyl Formamide, DMSO etc. but as a result only droplet spray and arc formation is observed, I'm unable to establish a stable taylor cone jet or nanofibres. Please provide me insights for electrospinning of only Carboxymethyl chitosan without any polymeric addition.
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Please try HFIP
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If the pairs are similar, will it reduce the adhesion due to electric charges?
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Using Standstill Time to Evaluate the Startup in Polymer ...
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National Institutes of Health (NIH) (.gov)
https://www.ncbi.nlm.nih.gov › articles › PMC10746984
by A Ptak · 2023 — The sliding pair was successively loaded with 25 N, 50 N, and 75 N, and the standstill time ranged from 0 to 10 min. The determined tribological ...
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Hello everyone, I am try to understand the differences interaction between insoluble and soluble polymers in water with metal ions and how theit charge density (of metal ions) affect the interaction.
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Dear Pablo Gonzalez, there are two criteria that define the solubility of a given polymer in a given solvent. First, they should have quite close polar/apolar character (reflected by the values of the solubility parameter). Second, the MW of the polymer should not be too high, i. e., below the critical MW for the occurrence of entanglements (these impede solubility by forming interchain knots). The interactions of metal inons with the polymer need the existence of ionizable groups on this later. These interactions in one approach is studied by the Manning's two phase condensation model theory. My Regards
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I am conducting free radical polymerization using Kraft lignin and MMA, with DMSO serving as the solvent and there is also an initiator. Following the reaction, I obtain a solution, but I am uncertain about the method to separate the solvent from the polymer. Could you recommend a technique to isolate solid polymer particles or powder, which I can then use for compression molding to evaluate its thermoplastic properties?
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Kraft lignin, MMA and their polymerized mixture are high-molecular compounds. DMSO is a low-molecular compound with a low boiling point. There are no problems with solvent removal at normal pressure or under vacuum.
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Hello,
I am looking to create a composite material by mixing or adding micropowder to polymer granules for use in a 3D printer. Could anyone provide guidance or methodologies on how to effectively achieve a uniform composite material with this approach?
Thank you!
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Good to know. Let's see. PLA is what is called a thermoplastic polymer (this means that it can be melted when heating and it will the solidify again to its original "form" when cooling). Being that the case, and considering your approach of creating filaments or pellets, the extrusion process would be the best thing to do.
I would use this approach:
1) In a rolling mill, or ball mill, mixing both materials, and grinding them as much as possible, to obtain a powder mix of the particles and the PLA.
2) That mix should go into an extruder (which is mainly composed by an screw, that is spinning), in which everything will mix accordingly. In this stage, normally in the extruder you can approach 200C, causing the melting of the polymer and a good dispersion of the particles within this melted matrix.
3) After that extrusion stage, when cooling, the polymer+particles material can be pelletized (because it will solidify), or you can directly obtain a filament that can go in the FDM printer. To do so, the diameter of nozzle in the extruder is an important detail to take into account.
I found an article that explains a bit about this, but with other particles, but the approach should work:
Since you have PLA, the approach of using solvents should be avoided, so for your observation number 1, I would not consider trying it at the moment. Nevertheless, to answer your question, when eliminating solvent you theoretically should obtain a solid again, but you should be careful, because sometimes some solvent molecules might get entrapped into the solid, causing bubbles or defects. If this solvent is trapped, and then you decide to heat the solid to melt it (because you are printing something), that solvent will be released as a vapour, and that might be a problem. Normally when using solvent, the idea is to use as less as possible and with a low boiling point, so it can be easy to eliminate.
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i need to know the required time
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Dear all, the following statement is taken from the reference below: " Aqueous polymerization of vinylidene fluoride at 123°C and 4.5 MPa for 18.5 hours using 0.8 g of DTBP and 35 g VDF resulted in a polymer yield of nearly 83%. " My Regards
Introduction to Fluoropolymers
Materials, Technology and Applications
2013, Pages 133-148
9 - Introduction to Vinylidene Fluoride Polymers
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Hello everyone,
I am currently pursuing a PhD in Environmental Engineering with a focus on microplastic studies. My background is in Civil Engineering, and I am relatively new to working with ATR-FTIR spectroscopy.
Therefore, I would like to seek guidance on the following:
  1. Interpreting Peaks: What are some best practices for reading and interpreting ATR-FTIR peaks, particularly for identifying different polymer types? Any tips on identifying key peaks related to common polymers would be greatly appreciated.
  2. Finding Spectral Libraries: I know the pre-installed library on my equipment (Micronlab) is somewhat limited. Could you recommend any free or accessible spectral libraries to help me with polymer identification?
  3. Recommended Literature: Do you suggest any specific books or resources for matching spectra, understanding polymer wavenumber and improving my interpretation skills? I know one paper by Jung et. al, 2017 (Validation of ATR FT-IR to identify polymers of plastic marine debris, including those ingested by marine organisms - ScienceDirect,
Any advice or recommendations from those experienced in FTIR spectroscopy, especially in the context of polymer studies, would be extremely helpful. Thank you in advance for your assistance!
Best regards
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Detecting small microplastics down to 1.3 μm using large area ATR-FTIR
Yuanli Liu a,b,c,d,*, Stephan Lüttjohann e, Alvise Vianello a, Claudia Lorenz a, Fan Liu a,
Jes Vollertsen a
a Department of the Built Environment, Aalborg University, Thomas Manns Vej 23, 9220 Aalborg, Denmark
b College of Environmental and Biological Engineering, Putian University, Putian 351100, China
c Fujian Provincial Key Laboratory of Ecology-Toxicological Effects and Control for Emerging Contaminants, Putian University, Putian 351100, China
d Key Laboratory of Ecological Environment and Information Atlas, Fujian Provincial University, Putian 351100, Fujian, China
e Bruker Optics GmbH & Co. KG, Rudolf-Plank-Straße 27, 76275 Ettlingen, Germany
A R T I C L E I N F O
Keywords:
LAATR
ZnSe
Ge
Microplastics
Spectroscopy
A B S T R A C T
Large area attenuated total reflectance-Fourier transform infrared spectroscopy (LAATR-FTIR) is introduced as a
novel technique for detecting small microplastics (MPs) down to 1.3 μm. Two different LAATR units, one with a
zinc selenide (ZnSe) and one with a germanium (Ge) crystal, were used to detect reference MPs < 20 μm, and
MPs in marine water samples, and compared with μ-FTIR in transmission mode. The LAATR units performed well
in identifying small MPs down to 1.3 μm. However, they were poorly suited for large MPs as uneven particle
thickness resulted in uneven contact between crystal and particle, misinterpreting large MPs as many small MPs.
However, for more homogeneous matrices, the technique was promising. Further assessment indicated that there
was little difference in spectra quality between transmission mode and LAATR mode. All in all, while LAATR
units struggle to substitute transmission mode, it provides additional information and valuable information on
small MPs.
1. Introduction
Microplastics (MPs) have gained much attention over the last decade
or so (Thompson et al., 2004), and thousands of studies have been done
to investigate the distribution, source, and fate of MPs to better understand
their potential threat (Bank and Hansson, 2019; Li et al., 2018;
Simon-S´anchez et al., 2022; Wang et al., 2021). Studies have revealed
that the presence of microplastics (MPs) in aquatic environments can
have adverse impacts on ecosystems (Ding et al., 2022b), including
potential implications for human health (Blackburn and Green, 2021),
highlighting the importance of understanding the occurrence of MPs in
natural and anthropogenic environments. However, a lack of harmonization
of methods and quality control procedures makes the comparison
among studies extremely challenging, hampering the scientific community
from obtaining a more comprehensive understanding of such
multifaceted pollutants (Cui et al., 2022; Ding et al., 2022a; Liu et al.,
2021).
The methodologies for detecting MPs have undergone significant
technological advancements, moving from simple visual inspection to
complex chemical detection (Fahrenfeld et al., 2019; Hidalgo-Ruz et al.,
2012; K¨appler et al., 2018). Fourier Transform Infrared Spectroscopy
(FTIR) is by far the most widely used chemical detection technology,
providing information about the chemical bonds of the analyzed material
(Cowger et al., 2020; Valls-Conesa et al., 2023). The FTIR spectra
can be compared to reference libraries for identification (Gaffney et al.,
2012), which are typically commercially available or custom-built for
specific purposes. There are three signal acquisition modes commonly
used for the detection of MPs, mostly depending on the size range of the
particles targeted: attenuated total reflectance (ATR) (Cowger et al.,
2020; Veerasingam et al., 2021), transmission (K¨appler et al., 2015;
L¨oder et al., 2015), and reflectance (Harrison et al., 2012; Vianello et al.,
2013). ATR-FTIR is routinely used to analyze larger particles (>300 μm)
mainly because of particle’s thickness and surface irregularity (Chand
et al., 2022; Liu et al., 2019). It requires limited sample preparation and
allows the analysis of thick and irregularly shaped materials producing
high-quality spectra not influenced by the thickness of the particle.
However, this approach requires a manual pre-sorting of putative MPs,
after which each particle is analyzed by ATR-FTIR, resulting in a long
analysis time. Smaller particles (<300 μm) are typically analyzed by
μFTIR, a combination of microscopy and FTIR that characterizes MPs in
* Corresponding author.
E-mail address: yuanlil@build.aau.dk (Y. Liu).
Contents lists available at ScienceDirect
Marine Pollution Bulletin
Received 6 August 2023; Received in revised form 18 October 2023; Accepted 12 November 2023
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Dear All,
I would like to ask about the relation between the surface energy and solidification of polymer. If we apply a chemical treatment such as NaOh solution or silane treatment on the surface of natural fibre, I wonder is there any linear or non-linear relation between them?
Thank you.
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Surface energy plays a significant role in the solidification of polymers. Here's a concise explanation of its effects:
  1. Nucleation: Surface energy influences the formation of nuclei during solidification. Lower surface energy can promote nucleation, leading to more crystallization sites.
  2. Crystal growth: The surface energy at the interface between the growing crystal and the melt affects the rate and morphology of crystal growth.
  3. Crystallinity: Higher surface energy can lead to reduced overall crystallinity in the solidified polymer.
  4. Morphology: Surface energy impacts the shape and size of crystallites, affecting the final structure of the solidified polymer.
  5. Interfacial adhesion: In multi-component systems, surface energy differences between components can affect phase separation and adhesion during solidification.
  6. Cooling rate: Surface energy can influence the required cooling rate for achieving desired properties in the solidified polymer.
  7. Surface properties: The surface energy of the solidified polymer affects its final surface properties, such as wettability and adhesion.
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I want to perform electropolymerization on 3 system carbon electrode. How to cover the reference and counter electrode? I want to make polymer only on working electrode.
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Archana Archana, it depends on what monomer you are using, we used to dissolve that monomer either in 0.1 M PBS or in 0.1 M H2SO4. Normally, it won't affect our reference (Ag/AgCl) or counter electrode (Pt wire), we can just wipe it out with distilled water to remove any debris, but covering is not possible.
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Deep etching
Negative photoresist
Acrylate polymer
Chemical etching
Ferric chloride
Crosslinking
Resolution
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The issues observed in the photos of the negative photoresist after contact with ferric chloride can be attributed to several factors. Here's an analysis and explanation of the possible causes:
Factors Leading to Negative Photoresist Lift-Off
  1. Inadequate Crosslinking of Photoresist:Cause: If the exposure time during UV curing is insufficient or the intensity of UV light is inadequate, the acrylate polymer may not fully crosslink. Effect: This results in a weaker resist that the etchant may be able to undermine, which causes the peeling or lift-off seen.
  2. Improper Development:: Incomplete development of the negative photoresist can leave unpolymerized regions, which can be attacked by the ferric chloride. Effect: These regions will lift off during the etching process, as seen in the images.
  3. Adhesion Issues:Cause: Poor adhesion of the photoresist to the substrate can occur due to surface contamination, insufficient surface preparation, or inappropriate baking conditions. Effect: This causes the resist to lift off when exposed to the etchant.
  4. Over-Etching:Cause: Extended exposure to ferric chloride can attack the photoresist, especially if it is not fully crosslinked or developed. Effect: The resist layer will start to degrade and peel off.
  5. Chemical Compatibility: Cause: The chemical resistance of the acrylate polymer may not be sufficient to withstand prolonged exposure to ferric chloride. Effect: The etchant penetrates and undermines the resist, causing it to lift off.
  6. Mechanical Stress:Cause: During the etching process, mechanical stresses can build up due to differential thermal expansion or contraction between the resist and the substrate. Effect: This stress can cause the resist to crack and lift off.
Recommendations for Improvement
  1. Optimize UV Exposure:Ensure that the UV exposure time and intensity are sufficient to fully crosslink the photoresist. Conduct a dose-response experiment to determine the optimal exposure conditions.
  2. Improve Surface Preparation:Thoroughly clean and prepare the substrate surface to enhance adhesion. Use a suitable adhesion promoter if necessary.
  3. Control Development Process:Optimize the development time and conditions to ensure complete removal of unexposed resist. Use a fresh developer solution and maintain consistent agitation.
  4. Monitor Etching Time:Carefully monitor the etching process to avoid over-etching. Shorten the etching time if necessary or use a less aggressive etchant if possible.
  5. Enhance Chemical Resistance:Consider using a different photoresist formulation with higher chemical resistance to ferric chloride or add a post-bake step to harden the resist.
The photoresist lift-off that was seen after contact with ferric chloride was probably caused by a mix of poor crosslinking, development, adhesion, over-etching, and maybe even the resist's natural chemical resistance. By optimising the exposure, development, and etching processes, and ensuring good adhesion and chemical resistance, the integrity of the photoresist during etching can be improved.
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In order to make a polyaniline film, I used the electrodeposition method and set all the conditions, but I noticed that the polymerization process is happening, but it doesn't stick to the substrate, but I changed the substrate more than once, and the solution is right, and the polymerization happens, I hope that you will benefit me.
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Hi Nina. Adhesion of PANI film to ITO depends on thickness and quality of PANI itself. These depend, in turn, on concentration of aniline, pH, temperature, background electrolyte (acid, salt) and on electrodeposition mode (CVA, potentiostatic or galvanostatic) and parameters (for CVA - sweeping rate, potential window, quantity of cycles; for potentiostatic- potential and time; for galvanostatic - current density and time). Typically the thinner film the better adhesion. Conditions of galvanostatic synthesis of good PANI film but on FTO are described in our paper
Rhese conditions fit also to ITO
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zzz
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If your solurton is turbid or otherwise does not follow Lambert-Beers law then maybe no. Depends on what you mean by "reliable"
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Polymeric film such as latex rubber substrate or polymer
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Dear all, you can simply add a plasticizer to break the intrinsic cohesion of the polymer. However, this approach has a major shortcoming, i.e there is risk of migration or leaching of all additives contained in the polymer including the plasticizer itself. The best strategy is via grafting of short segments side groups to the main polymer chain backbone with good affinity to the swelling solvent. In this approach internal cohesion is reduced by the grafts as they act as chain spacers, with no tendency to migration upon swelling. My Regards
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Hello,
Is there anyone with expertise in polymer stabilization agents?
I am looking for a scientific solution to stop a polymerization reaction and am open to any suggestions.
Thank you for your responses.
Best regards,
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Dear Ines Bennour, your question hasn't a precise subject. Stabilizer against what? Thermal, light, ....
To stop a polymerization you need quenching conditions. By addition of an inhibitor (hydroquinone)or chain termination compound (mercaptan). Which type of polymerization reaction you work with: polyaddition (chain growth) or poly condensation (step growth)? My Regards
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I wonder the tendency of coefficient of thermal expansion (CTE) of polymer which has different chain structure. In my opinion, CTE will be higher when the polymer materials has high interaction between the polymer chain. But, some reference said it's not true. So, I want to receive some opinion by many researchers.
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Dear Park Jun Woo, chain flexibility with multitude of possible conformation changes is the essential factors dominating linear CTE. Expansion happen once the barrier of intermolecular cohesive energy is bypassed, which is necessary for segmental chain motions, this is the reflected by the value of Tg. All factors working against chain flexibility will such as rigid segments, bulky side groups will work against the ease of thermal expansion, and will shift the temperatures to higher input. Other secondary factors such as heating rate and polymer composite and additives have their additional effects. My Regards
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To prepare polymethyl methacrylate polymer for the study of acoustic properties, a mixture of methyl methacrylate monomer and benzoyl peroxide is used. This mixture is then heated and placed on a heater. To prevent the formation of bubbles during this process, what measures should be taken?
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Dear Sana Mohammadi, you are not following the proper way of a radical polymerization. The first remark is temperature should be controlled at a specific one. Putting directly your recipe on a heater will make temperature rise to higher values (formation of bubbles). A thermostated bath is the most used. First, you should purify your initiator (recrystallization), monomer (washing with concentrated alkaline solution or distillation to remove the inhibitor/stabilizer), purify solvent. Prior to addition of the initiator, O2 removing by inert gas (N2) stripping. If you don't have an experience with polymer synthesis, then take help of an expert in this matter form your vicinity. My Regards
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When adding the semiconducting particles to the polymeric matrix, any changes in (Lamda) of the matrix, meaning no changes in the gap energy of the latter. This phenomenon does not follow the literature because of the mixture of conducting particles and insulating matrix. I mention that in the reflectance measurements, the effect of semiconducting charge is seen, i.e. adding semiconducting charge decreases the gap energy of the matrix.
In the attached file, an example of a measurement made using UV-Vis spectroscopy.
Can anyone help us give an interpretation of this behavior? thank you.
Regards
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I would assume that the diameter of the particles relative to wavelength is very important. If the diameter is very small relative to wavelength, you get an effective medium, whereas if not than it is like a mosaiced surfaces. I hope this helps!
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I am working on a new polymer whose (hkl) values are not reported in the literature. How can I find out the (hkl) values of the XRD peaks?
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You can find hkl values through High score from XRD data. I can do it for you.
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