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Composite Resins - Science topic

Synthetic resins, containing an inert filler, that are widely used in dentistry.
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I have tried to cure the CNSL resin with a Hot air oven of 180 degrees Celsius. Still, I am not getting the proper solidification of the resin, the specimen which is kept in a Hot air oven is in a spongy state. I want to know the process/ steps/ procedure for curing the CNSL resin?
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Cashew Nut Shell Liquid - an overview | ScienceDirect Topics
https://www.sciencedirect.com › topics › engineering › ca...
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Hello Everyone
I want to use XRD test to investigate the exfoliation of graphene in epoxy resin. For doing this test which method is better and why?
1. using powder of samples?
2. Using the bulk sample?
Thanks
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The average crystalline size of the have calculated by the Debye-Scherrer equation 𝐿𝑐= 𝐾𝜆/𝐵 cos𝜃
The interlayer distance have calculated by Bragg’s equation 𝑑= 𝑛𝜆/2sin𝜃
Graphene layers=𝐿𝑐/d
Miraidin Mirzapour You can refer to the following doi
http:://doi.org/10.4038/josuk.v14i2.8036
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Dimension in LengthXWidthXThickness for an epoxy resin composite for Mechanical Studies.
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From a more general point of view, what you are asking for is generally called a "MRV", as in Minimum Representative Volume.
That is, the minimal volume you can work upon and have a representative result for bigger scales.
I can't help you with your specific issue but when MRV is not known, it should be researched : measure whatever you are measuring on different volumes of growing dimensions and look for when the result stabilizes. This would be your MRV for THAT measurement (not necessarily for others).
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I am trying to fabricate PVDF membranes via phase inversion using 12 wt% solution in DMA. When I cast the solution on aluminum or Plexiglas plate using membrane applicator and put that into water bath, a thin uniform membrane does form; however, it gets permanently stuck to the aluminum or Plexiglas plate and cannot be separated. Can anyone describe the reasons and suggest some solutions?
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What is the polymer molecular weight?? because it is an influential factor in the preparation of the membrane?
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I have stadium stairs made of concrete, and i need to pick an adhesive material that give a good bonding strength and can resist some environmental factors such as hot and cold weather without peeling off. ( ceramic- polymer composite).. I can،t wait to read your esteemed answers.
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I would like to recommend Silicone Rubber Compounds - RTV 2 components which perform the ability of high thermal conductivity and adhesive. Some famous brand names which you can refer ShinEtsu, Momentive, or Dow-Corning.
References:
Best regards.
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Hello,
I am actually working on the Degree of Conversion of dental resin composites in my lab.
When I perform my FTIR analyses, I apply the equation to calculate the DC (the equation is not wrong, I have already checked that) and I always obtain some values turning around 6% for the best polymerized resin. However my curves appear to be good and the peaks are the same than everybody in the literature (1608cm-1 and 1638cm-1).
You can find in the attached file an example of the curves (red non polymerized, blue polymerized). Sorry if the legend is not in the good order.
Did anybody already have such a problem with the calculations and do you know how to change it ?
Thank you so much
Best regards
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Dear Thibault Canceill, which mode of FTIR you are using (transmission, ATR, ...)? Do the spectra are at the same base line? The papers I checked give conversions above 30%! Please check the following documents. My Regards
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Hello dentists, I'm wondering if pre-heating resin composite for luting use with Inlay and Onlay, may increase shrinkage phenomena or not ? If yes, is there any difference in shrinkage rate between nanohybrid resin composite and glass fiber-reinforced composite ??
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Subgingival located cavity margin, inaccessible area. Complete isolation and dryness might be challenging.
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Bestoon Faraj Wonderful question and i do agree with the expert views
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Using Spectroradiometer to measure samples, can the color of the background be ignored?
Neutral gray, black, and white backgrounds are often used for color measurement. Will the use of spectroradiometers eliminate this factor?
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Dear Alperen, apparently you are using a spectroradiometer in reflection mode, so I will assume that in this answer. In reflection measurements ideally only photons are detected that come back from the sample to be measured. Hence, a totally black truly spectrallt neutral background would be best. To set your exposure time, gain, slit width and aperture, preferably use a spectrally neutral known grey-tone that returns light just a little above the spectral peak value of the sample to be tested. This provides you with optimum dynamic range.
Also recommend to download and read the free Light Measurement Handbook by Alex Ryer.
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If I don't have aesthetic concerns, I prefer glass ionomer (Equa forte). I use bulk-fill composite in deep cavities. So, you?
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several restorative material and approach available, case and protocol might have a major role and minor role for the operator preference.
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I believe that despite the progress in developing newer dental materials esp. composites trying to mimic the role of calcium hydroxide and other dental products in forming dentinal bridges, these restorative materials can still illicit unwanted and unnoticed immune reactions within pulp when placed within < 1mm of RDT (Remaining dentin thickness)
I would like to know about anyone and everyone's opinion on this area. Thank you.
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Schmalz et al. (J Endod 2001) showed very nicely that only at <300 microns RDT there is a significant increase regarding permeability. Since then, I do it exactly like they showed 20 years ago: <300 microns (visible pulp shining through) Biodentine, all other areas bonded resin composite. An our clinical studies prove it.
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We know that fiber-based composites are directional dependent, What happens when the load is applied in the normal direction? If fiber is strong enough, whether it will give the same results irrespective of the direction?
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Dear all, I have a small addition to what Dr. Pierluigi Traverso recommanded. When fibers are unidirectional, stress testing in normal direction to the fiber is done mainly to test how is the interface fiber-matrix, i.e., the state of adhesion at the interface and its coherency in stress transfer. My Regards
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How the diameter of the fiber plays a role in interfacial bonding? If the dia of Fiber is small, we assume the matrix will completely adhere to the fiber. If the dia is larger, the same matrix covers the fiber. Whatever the surface area might be. It depends on how good it binds the fibers. But how this dia play a role in that?
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In summary mechanical properties of thermoplastic fiber reinforced compounds are largely influenced by fiber orientation and fiber length retention ( shorter ones result in higher number of fiber ends, where premature failure of polymer matrix usually occurs) , that reflects low fiber breakages during processing and good fiber wetting ( to promote a continuous phase) . However these are opposing factors as good fiber orientation and wetting requires higher shear that causes fiber breakages. Thus to get a more appropriate balance one has to choose an appropriate screw configuration , and paly around extrusion residence time.
Other points to consider are :
. fiber properties
. fiber sizing ( that will react with adhesion promoters / coupling agents to result in a stronger interface between fiber and polymer matrix)
. type and amount of coupling agent
. kind of extruder used and screw configuration
. location of fiber let down in extruder
. extrusion residence time
. polymer viscosity ( will tend to affect wetting performance as well)
. the diameter of the fiber will affect the critical fiber length , defined as the minimum length required for the maximum fiber stress to achieve the ultimate fiber strength at its mid-length , estimated by :
*Lc = (Ultimate fiber tensile strength X fiber diameter )/ ( 2 x interfacial shear between the fiber and the matrix), under the assumption that both matrix and fibers show a linearly elastic responses.
* more details can be found :
. Kelly, A. and Tyson , W. R., J. Med. Phys. Solids, 13, 329 - 350 / 1965
. R.A. Malloy , plastic Part Design for Injection Molding , Hanser Publishers, New York, 1994, page 265.
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I am working on graphene nanocomposite resin for SLA 3d printing. Many researchers used Probe sonication for dispersion. What is the drawback of using bath sonication as high energy in probe sonication can cause defects to graphene.
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The power (W/L) of the sonicator is an important phenomenon while mixing graphene nanocomposite with resin.
The bath sonicator has less power compare to probe. The high power sonication may create a defect in the nanocomposite.
Kindly optimize the applied power, sonication time, loading amount of nanocomposite with resin, and temperature while sonication all is critical parameters.
The defects in graphene can be controlled by optimizing the above-mentioned conditions.
High power sonication can damage the graphene nanocomposite structure. On the other hand, low power sonication leads to poor dispersion
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how to test the durability of the fiber reinforced polymer composites?
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Durability is a general term that can be characterized based in the specific approaches of FRP conposites.
For instance, tje followinf paper utlized GFRP material as an alternative of steel material in pile to enhnace the durability of pile foundations against corrosion. It is also investigates both axial and bending responses of pile foundations.
Effect of Fiber Reinforced Polymer Tubes Filled with Recycled Materials and Concrete on Structural Capacity of Pile Foundations
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Before and after curing, how moisture can play a role on the residual stress of a GF/PF resin composite material. What will be the effect of %RH on the composite before and after curing ? How does it affects its flexural properties ?
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Hi Pramit Dutta, if you are talking about the laminated composites with fabric glass fibers. The curing usually can improve the interfacial properties of the composites and reduce the microvoids or defects somehow. So the moisture will have less effect on the curing ones. For the flexure properties, the composites may have delaminations depending on their interfacial properties. The delamination will cause early failure of the composites leading to weaker mechanical properties.
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In order to find and fabricate a proper alternative counter electrode rather than Au or Ag in Perovskite solar cells(PSCs), the preparation of a convenient carbon paste is essential. This feature of convenience includes high conductivity as the first and most important one. Therefore, the binder plays a major role in the composition of the paste formula. Is there any polymeric/resin/composite that maintains the adhesiveness in the contact along with high conductivity(i.e low sheet resistance)? please do not hesitate to tell me your suggestions. I am keenly looking forward to it.
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I think N-Methyl-2-pyrrolidone (NMP) is proper solvent for dispersing PPy and PANI powder.
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Hello,
I m growing primary gingival fibroblasts, to test the cytotoxicity of dental composite resins. in addition to that, I have been doing gene expression analysis of these cells.
recently I have noticed that these cells act differently after passage 10?
Is it recommended not to use these cells after 10 passages?
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Please see the linked document. It shows how many passages are recommended or acceptable in the laboratory.
Regards,
Mario
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In this composite, I have used bisphenol A epoxy resin (LY556 with epoxide equivalent 5.44 eq/Kg and aromatic amine based hardener Aradur HY5200 with amine value 630 eq/Kg.
How can I calculate the degree of cross-linking between this thermosetting system?
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There are different possibilities. You may p.ex. check the rest of enthalphy. You can also make DMA measurements and compare it to a part which was cured very long (> 1 week) at 10 °C over the Tg.
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I have been trying some ratio's of Polyurethane Resin to Glass Fiber Cloth but my young modulus results come up medium to low (15.000 MPa circumf. and 8-10.000 axial) and my Poisson ratio quite high (0.4-0.7). Have you got any suggestions?
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the best ratio is Resin:fibre=40 vol%:60vol.%
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Which are the most preferred ceramics for dental implants?
TIA
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The most dental ceramics preferred to restore dental implants are monolithic zirconia, lithium disilicate, zirconia layered with felspathic.
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When surface modifying high K ceramic particles like BT, BST or BZT for use in a high k ceramic/polymer composite film, some researchers say they get higher permittivity in the final film when the particles' surfaces are modified with, for example, an acid like gallic acid or phthalic acid. At the same time, other researchers say a low ph causes barium to dissolve from the particles' surfaces and they talk like it is a bad thing and say the ph needs to be kept higher? Who is right?
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Thanks but I'm well aware of what BT is already. Companies sell high k ceramic particles embedded in polymers to make a composite film rather than sintering into dense films of only the high K ceramics. Many researchers study how to make even better composite films.
Here is one example:
They are getting good results with acidic surface modifiers of their BT particles yet other researchers are saying not to go acidic because it causes Barium ions to come off the BT particles' surfaces and they act like that is a bad thing.
So my question is who is more correct and why?
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I have results for dynamic strength of resin at a higher strain rate. I want to use these results to evaluate material properties of CFRP at the higher strain rate assuming fiber strength isn't affected significantly by higher strain rate. I want to use this model of impact loading test using a macro-scale model (Fibre and Resin are not separate) hence I can't use the Cowper-Symonds model. Also, how to implement this model for impact loading simulation? If using meso-scale simulation is one of the option what is the procedure that can be followed?
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Good question
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I want to compare three models will be used to make IC chip. The models consist of:
Model-1 (Silicon carbide, Resin and Silicon nitride)
Model-2 (Tetrahedral amorphous diamond, PVC and Alumina)
Model-3 (Tungsten carbide, Natural rubber and Tungsten)
The materials are used in each model to make composite. In Model-1, SiC is used as upper material, Resin as adhesive and SiN as lower material. Can PVC in Model-2, natural rubber in Model-3 be used in making IC chip? If not, please suggest other isotropic materials.
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Dear Md,
welcome,
If i understand your question you want to build build a stack of materials. You have to give what are the properties of the stack you need and what are their uses. You have two metallic layers which you want to join them by a third organic layer. In the first model you selected the resin as an adhesive an intermediate layer. In model 2 and 3 you can use a resin to join the three materials.
Best wishes
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I have stress strain curve of resin at varying strain rates. I want to implement this strain rate dependent behaviour of resin for impact simulation of a CFRP tank in LS DYNA.
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First, organize the experiment data.
Convert true stress-true strain using nominal stress-nominal strain.
Then find the equivalent stress-equivalent strain relation for the LS-DYNA model.
Finally, using DEFINE_TABLE, considering the data of each strain rate.
Check the example file, please.
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I have stress strain curve of resin (attached as image) at varying strain rates. I want to implement this strain rate dependent behaviour of resin for impact simulation of a CFRP tank in LS DYNA.
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I study the delamination of laminates upper and bottom skins of honeycomb composite structure simple supported from two sides and under bending stress.
I consider the developed tension on the bottom skin as the main peeling force that cause delamination.
Is my thinking correct?
Also, do you suggest textbooks?
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Shaktivesh .. Thanks very much.
I do analytical calculations
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I'm looking to culture human oral fibroblasts to test cytotoxicity of composite resin.
So far I've had no luck in isolating fibroblasts from a 2mm of excised gingiva.
Can anyone share techniques to improve isolation?
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Sanaa Ibrahim How frequesntly should I change culture media then (DMEM = 10% FBS)?
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We conducted the tensile test of the CFRP.
So, we want to observe the fractured surface of the CFRP using 250x microscope.
Can we observe sufficiently the fiber and resin in that surface using 250x microscope?
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Eu-Tteum Park Do any of your colleagues have a similar microscopes that you can check out before you buy one? I think 250x should be fine but you'd need to see it yourself to make sure it will be up to your standard. In cases like this, the acceptable level of magnification is pretty subjective.
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I need to perform tensile testing on samples of glass fiber - epoxy resin composites. the fiber is chopped ( discontinuous ) and randomly distributed.
I found different information about which standard to follow, some sources recommend ATSM D3039 which has a sample thickness of 1mm and other sources recommend using ATSM D638 ( because my fibers are discontinuous ) which has range of specimen dimensions.
Which standard should i follow ? more specifically what is the recommended thickness for my case ?
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Good morning, D3039 is for long fiber composite and laminate. For chopped reinforced composite you can correctly use D638 that is for plastic material. For dimension you have to consider the capacity load of your test machine. If you can, considering machine is batter to have a tickness not lower than 3 mm better is five and width not less than 10 mm with gage lenght 100 mm
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Matrix degrade early due to UV, moisture etc. Please suggest the possible methods to prevent such degradation.
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Please check following prior art (nano-ZnO and graphene, both at 0.5% w/w) :
Partially reduced exfoliated graphite oxide should be most fit as it combine protection properties of graphene sheets and strong reinforcement because of presence of carboxyls (the last will react with amine-groups from epoxy-composite. Addition of Fe-salts and subsequent calcination allow to get radioadsorbing ( "stealth" ) coatings.
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I am wondering the critical resin properties such as viscosity which are important during manufacturing of towpreg, prepreg and slit tape based on epoxy and glass or carbon fabrics. Thank you.
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YOU HAVE TO RESPECT THE CROSSLINKING TEMPERATURE(gelification and vitrification temperature)
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I am working on the enhancement of mechanical properties of resol. Sometimes we add alkylating agents during synthesis of resoles. My question is why we add alkylating agents? Do they affect mechanical properties of resinand what is the best controlled composition of this resin?
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Alkylated phenolic resins are often used to cure with rubbers or elastomers, for example to manufacture tires. It can result thermoplastic with elastic characteristics, with enhanced physical properties of such hybrid resins like hardness and tear resistance. Actually the alkylation of the phenolic resin does not play a role in the mechanical properties; it is rather to be compatible with the rubber (the non-alkylated phenolic resins are not so miscible with hydrophobic rubbers). Afterwards, what could be the best composition of phenolic resins for improved mechanical performances? Hard to say. The list of potential additives (which are already known) is long. It shall depends of your application goal, and the side properties you would like and those you don't want.
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What are the Parameters to be considered, While Sonication ?? What are the amplitude, frequency and timing need to be maintained? 
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Yes of course .
Please see can you paper:
Effect of bubble based degradation on the physical properties of Single
Wall Carbon Nanotube/Epoxy Resin composite and new approach in
bubbles reduction
Seyyed Alireza Hashemi ,, Seyyed Mojtaba Mousavi
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I am searching for Photocurable (e.g, UV curable) liquid resin which can be dissolvable after curing (Dissolvable only in chemical solvents but not in water). Where can I get it?
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like aceton
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I would like to know what are some viscosity values during filling stage of RTM procedure as also during the curing procedure.
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viscosity test
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I search for auxetic materials suitable for nanofiltration application.
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Hello Wibke,
Normally materials with negative Poisson ratios known as auxetic materials. So I think it is a broad term. talking about a porous auxetic I can think of Zeolite or PU foams. Zeolite which is natural porous materials has used for filtration and catalysis process. very easy to source and kind of cheap. PU foams practically are everywhere :)
Hope it helps,
Regards
Amin
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Dental resin polymerization
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Hi Amin,
Thank you for your answer :) 
Kinds,
Zeynep
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Anti-Sinking Composite Materials for Ships.
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نعم تستطيع ولكن بيا برنامج
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I have been looking for sometime without success on the web and in the literature for a curable polymer with an intermediate Youngs Modulus range:3MPa-500MPa.
Could anyone give me some suggestion on this?
Thanks
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Hi,
I think PVDF should be good..another polymer we looked at is polyurathene..wat do you think?
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I would like to run DSC on a prepreg resin and calculate heat of cure.  I will need to get resin sample without any fibres.
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I agree with solution suggested by Emmanuel. You can first go for analysis of fibre using TGA. dont keep sample temperature more than what is suitable for degradation of fibre. Alternatively, you must be knowing the degradation temperature of fibre. You can substract the enthalpy at that particular temperature and carry on with that of resin. TGA would be more appropriate and suitable. 
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Our team is using FEI Quanta 450 FEG for SEM analysis for the first time. We are testing materials like membrances and carbon fibre brush carrying microorganisms. Can you help us with pre-treat methods, materials and techiques to prepare such materials (mentioned above) in order to enhance our analysis? 
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Some material didn't need any treatment like cds with thinker layer due to its ability for electron beam but some material such as polymer should be coated with conducted layer with thikness not more 10 nm like gold...
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this is the SEM image of a cement sample, I cannot see any variation in the phases  such as C3S, C2S, C3A, C4AF. I did not use EPOTEK 301 as it is expensive and used araldite (epoxy and resign). should I change the resin to a low viscus to get results. 
your feedback is important to me.
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I do not see any problems with polishing. Of course magnification is a bit low to see if it is a problem. Resin infiltration under vacuum is a good idea (infiltration was not sufficient). No advice on cement - not my field.
Overall brightens of images is too high, makes it a bit more difficult to analyse them. 
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The samples will be used for tensile testing directly after spinning. I'm trying to avoid damaging my sample and do not want to use the SEM to measure the thickness. Any suggestions will be greatly appreciated. FYI, the fibers are spun on two stationary plates. The mats are extremely thin.
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Via the link below you will see some measuring methods. Sample weight can also be an alternative for thickness.
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Is it possible to reach the maximum Tg of an epoxy resin with postcuring ? For example, if I would cure an epoxy resin at room temperature and postcure it with active heating until no conversion can be detect anymore. Does it reach the same Tg as an epoxy resin which is freshly mixed and immediately cured by active heating ?
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Post curing is the process of exposing a part or mold to elevated temperatures to speed up the curing process and to maximize some of the material's physical properties. This is usually done after the material has cured at room temperature for at least couple hours. In general, you should reach the same Tg if to obtain similar degree of curing. Please make sure nothing get lost during the curing, and the ratio of epoxy and hardener are similar for both cases, especially if you cure the materials at elevated temperature. The appearance of the materials should be similar too.
Hope this will help.
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Hello,
I am trying to adhere carbon fiber plate together. Do you know which brand has the strongest epoxy based resin?
Thanks!
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Araldite is good resin for bonding.
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I am studying a paper that uses both resin and matrix.
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Matrices: Can be inorganic and organic
Organic: Polymers are common matrices (especially used for fiber reinforced plastics). Typically, most common polymer-based composite materials, including fiberglass, carbon fiber, and Kevlar, include at least two parts, the substrate and the resin. In polymer chemistry and materials science, resin is a "solid or highly viscous substance" of plant or synthetic origin that is typically convertible into polymers. They are often mixtures of organic compounds.
In polymer, though thermoset and thermoplastics sound similar, they have very different properties and applications. Thermosets are materials that undergo a chemical reaction (curing) and normally transform from a liquid to a solid. In its uncured form, the material has small, unlinked molecules (known as monomers). The addition of a second material (cross-linker, curing agent, catalyst) and/or the presence of heat or some other activating influences will initiate the chemical reaction (curing reaction). Thermoplastics are melt-process able plastics (materials that are processed with heat). When enough heat is added to bring the temperature of the plastic above its melting point, the plastic liquefies (softens enough to be processed). When the heat source is removed and the temperature of the plastic drops below its melting point, the plastic solidifies back into a glass-like solid. This process can be repeated, with the plastic melting and solidifying as the temperature climbs above and drops below the melting temperature, respectively.
Inorganic: Cement (concrete), metals, ceramics, and sometimes glasses are employed.
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Adding 
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Yes, it gives the good strength as compared with the normal strength concrete, many researchers has developed high strength concrete through steel fiber.
I hope attached file is more helpful fou you, for in-depth understanding about steel fiber reinforcement and its performance.
Best regards,
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I need information or article about body bus manufactured with fiber glass reinforced polymer and rollover test requested by UNECE R 66.
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Good day to all. I need advice on preparing nano zirconia in polymer. After inside the zirconium precursor with acetone,water and acid, I cast my mixture but then in few day I notice that white solid layer on the bottom. I think my zirconia not mix with my polymer. If i prepare silica as the filler with the same procedure, the end dried sample is completely homogenize. Kindly need advice on this matter.Your attention and comments are highly appreciated.
Thank you
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Your question is not clear and can you tell us a little background.  What Zr precursor are you using? In your case, you may not not forming ZrO2, instead you might have hydrated Zr (i.e. Zr(OH)4).  You need to reduce it to ZrO2, then mix with polymer.  
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 My working in a fiber plant. we use DMAc for solvent
I last week, we have a fire is system spinning. Now, i am trying to find some standard operation to prevent the fire in next time.
 - The polymer, have 65% DMAc, is dried by hot air at 270 degree celsius - open system.
I will calculate the concentration of DMAc in the air ( volume ~ 1.3m3) and the volume hot air is used. After that, comparing it with the temperature. It's is possible ?
I want to find some document or reference about this problem. I hope someone can help me.
Thanks you very much.
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thank you very much for your assistance
but, It is too general, the flammable limit in air and auto ignition temperature aren't constant. It depend on several factor.
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My fiber is Pineapple. I wanted to know if increased hydrophobicity could lead to increased tensile strength
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Hello,
It depends on the treatment you apply on your plant fiber as well as the treatment parameters. A number of treatments are available for imparting hydrophobicity on plant fibers, namely, alkalization, bleaching, acetylation, silane treatment and graft polymerization. These treatments may affect mechanical properties positively or negatively in the short term. However, their long term effects tend to be positive as they preserve the fibers by avoiding swelling, rotting, biomicrobial attack, etc that take place in the presence of water.
Below is a list of treatments that are applied on fibers taken from (Yılmaz, N.D. “Agro-Residual Fibers as Potential Reinforcement Elements for Biocomposites”, Chapter 11, in “Lignocellulosic Polymer Composites: Processing, Characterization and Properties”, Ed. Thakur, V.K., Wiley -Scrivener, USA, ISBN 978-1-118-77357-4, s. 233-270. ,2015)
"
Some chemical treatments may act as removing extra-cellulosic materials. Others,
like those utilizing silane or maleated agents, provide a surface coating via a chemical bond reducing the hydrophilicity of the fiber and improving the adhesion to the polymer matrix [15]. Chemical treatmens lead to decrease in variation of properties, as Moniruzzaman et al. [73] reported for okra fibers. They also reported that different chemical treatments lead to further separation of okra fibrils, which hold loosely together after retting.
11.7.2.1 Alkalization
Alkaline treatment (mercerization) is one of the most common chemical methods
applied to plant fibers which are used as reinforcement in biocomposites. Alkalization partially removes lignin, wax and oils covering the surface of fiber cell wall [3]. Thus, alkalization improves the surface adhesion of fiber to the polymeric matrix with the removal impurities which results in a rough surface topography [8].
[...]
11.7.2.2 Acetylation
The acetylation treatment decreases the hydrophilic nature of the plant fibers. During the acetylation treatment the hydroxyl groups in the cellulosic fiber are replaced with acetyl functional groups. The decrease in hydrophilicity results in lower moisture intake and stronger interfacial bonding [8]. De Rosa et al. [15] obtained lower water content in acetylated okra fibers compared to untreated ones. Hill and Khalil [72] reported that the acetylation treatment enhanced the  bioresistance of coir and oil palm fiber-reinforced polyester composites.
11.7.2.3 Silane Treatment
By forming stable covalent bonds, the silane treatment would improve the contact
angle against water by increasing the hydrophobicity. The mechanism of this treatment can be explained as a silane chemical reacts with water and forms a silanol and an alcohol. With the moisture present, the silanol reacts with the hydroxyl groups of the cellulose and bonds itself to the cell wall [8].
Decrease in water absorption behavior is reported to occur with silanizing of banana stem and bunch fibers [26]. Ganan et al. [26] reported an increase in contact angle and decrease in surface free energy and polar component. They found silane deposition on fibers surface according to Fourier transform infrared spectrometry (FTIR) analysis.
11.7.2.4 Bleaching
Bleaching causes the fiber parameters to become more uniform [5]. Due to removal of some extra-cellular materials, the degree of chrystallinity increases [28], fibers acquire a whiter color and the inherent yellowness is decreased. Fibers lose some weight and become finer [12]. Increase in water absorption was reported to occur with bleaching of okra bast fibers. This might be due to the removal of hydrophobic substances which exposes hydrophilic cites [5]. Contrarily, the water absorption of banana fibers was reported to decrease from 61% to 45% for 70 hour water immersion upon sodium hypochlorite bleaching [28].
[...]
11.7.2.5 Enzyme Treatment
The utilization of enzymes in the natural fiber modification field is rapidly increasing.
This trend may be due to the environmentally-friendly nature of enzyme treatments
as the catalyzed reactions are very specific and the performance is very focused [3].
Several enzymes have been used in order to enhance the effectiveness of extracting fibers from the agro-residue or fine-tune the properties of extracted fibers such as lowering their diameter. Xylanases, cellulases, pectinases are the enzyme types that have found more use in agro-residual fiber modification [12,13,38].
[...]
11.7.2.7 Graft Copolymerization
The compatibility between the hydroxyl group containing polar cellulose fibers and
apolar polymer matrices may not allow for production of high mechanical performance biocomposites. In order to overcome this difficulty, a third material, a coupling agent can be introduced that modifies the interface morphology and the acid-base reactions in the interface, the surface energy and wetting efficiency [8].[...]
``
Best Regards,
Nazire
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Can be any product but the result must be a soft polymer, like a market bag
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Dear Marcelo, give a look to epoxidized vegetable oils. Probably you can find some not expensive. Regards
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In general, which type of resin has the greater exothermic energy during the curing process in the same environmental conditions?
Thanks for your reply 
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To bond polyacetal (POM), firstly, I used chromic acid to prepare the surface of polyacetal and then tried some adhesives like cyanoacrylate, epoxy, PVC, and polychloroprene (Pattex, Henckel) adhesives but none of them showed good bonding. Could any body help me to find a suitable adhesive formulation and may be procedure for polyacetal bonding?
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Plasma etch POM, followed by Loctite 770  primer and bonding with Loctite 401 Prism cyanoacrylate adhesive. If you need even stronger bond then in addition to adhesive either join the POM parts by POM setscrews set with above adhesive, or mate parts by dovetail design, or both.
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Microgranule contains both silica and polysaccharide polymer. Want to etch silica with NaOH but don't want to disrupt the structure of polysaccharides.
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I only know HF.
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The nature and type of adhesive used in manufacture of composites depend on the end use of the composites.We plan to use urea formaldehyde resins for our wastepaper based composites.Any alternative or suggestions.
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Urea formaldehyde resins are widely used but tend to decompose in hot humid locations. Ligands derived from wood are sometimes used in rigid constructions. Low and medium temperature melting glues of waxy types are used in hand crafts. Best advice is to use a glue that is recommended by the manufacturer for the purpose you have in mind. 
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I am working on a high modulus adhesive. I am preparing dog-bone samples for tensile tests, I've tried to vacuum the adhesive in different ways like several short periods and each time skimmed it and vacuumed again, another way I vacuumed samples in a long period and cured them Simultaneously, but I can't eliminate voids and have a prefect sample.So, If  you can offer me some tips to increase the quality of  my samples
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We use the fiber glass fabric impregnated with glue, instead of ready plastic and the problem of qualitative samples is removed
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Hello, I need the best industrial process for production of urea-formaldehyde resin with molar ratio of 1.1 suitable for MDF and particleboard production with continuous hot press and prepress. With special thanks
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 Dr. Javad Balou,
Have you read the book chapter by A. Pizzi on aminoresin wood adhesives (In: Wood Adhesives, Chemistry and Technology)? If not, this chapter has good discussion on control of UF reaction and goes into some aspects of particleboard production with UF. With the very low formaldehyde ratio to urea that you are looking for, the challenge is to maintain the strength and swelling properties of the particleboard. You will need to use more hardener with UF resins at a low F/U ratio since the gel time is slower. if your intent is to have low F emissions, maybe try 1-2% tannin extract. Also, it is recommended to have continuous control of the pH and viscosity during the reaction.
Best
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Best curing method of composite resin filling
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Clinical trials had show that it´s important not to dissicate dentin after cavity preparation. You can use a Calcium hydroxyde liner, phosphate silicate liners or a glass ionomer. Type of Adhesive and  handling properties is another issue to consider to prevent adhesive failure to asure marginal sealing to prevent microleakage.
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Polymerisation shrinkage, adequate curing, c-factor reduction
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First off for those who don't look back but for 5-10 years in the dental literature you are doomed to repeat the newest philosophies without considering the history and outcomes.  Back in the early 1980's we researched the curing abilities of composite resins penetrating the light from the facial and lingual aspects and measuring cure by hardness and bonding to enamel.  Then by bonding to dentin.  The long and short was that we could cure through 7+ mm of tooth from the facial, say through a maxillary cuspid to use a light cured composite resin, Silux, to bond metal phalanges of acid-etched resin bonded fixed partial dentures.  The bond were the same as composite resin to enamel and the the hardness below the brackets when debonded was the same as buttons of  the composite resin discs 1X20 mm used to test water sorption.  We then took it to a Pedo grad thesis and to orthodontic brackets for 6X6 and now today this is the way Fast Braces bonds their brackets.  Dentin microleakage of bulk placed restorations cured through the facial and lingual interproximal areas were measured and were actually slightly better than horizontal placement techniques.  I have just retired from 40 years of private practice, military practice, teaching and Biomaterial and Clinical research (having received a MS in Biomaterials and Clinical Research in 1988).  I used this technique in my private practice for over the last 20 years and my composite resin placed from my records have lasted an average of 14.5 yrs for all composite resins, Classes 1, 2, 3, 4, 5, all bulk filled and cured through the enamel facial and then lingual surfaces of the tooth and interproximal spaces.  None of the classes stick out in statistical significance, that is to say just as many Class 2 failed as did the other classes.  So I have seen that incremental, horizontal and vertical, and by the way several papers find no real significance to leakage placing either horizontal or obliquely, is no better and much slower than bulk placement and additionally curing for 20 sec through the facial and lingual surfaces.  And for the skeptics, I did not have patients reporting sensitivity after placement of composite resins.
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we are looking for this resin to make our product.
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For Phenol farmeldahyde resins availability in Pakistan the detail can be find out from Gaffor Chemicals. The detail information is available online.
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how can i removed bubbles formed during mixing epoxy resign & hardner i am using Araldite AW106 and hardner HV953. How to degas the mixture?
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Depending on the epoxy and hardener used, viscosity, gel-time and of course the way you add the hardener into epoxy and the way you mix it can introduce a lot of bubbles.
If you have enough time before gelling, you can use vacuum. Other option use Thinky mixer
Bubble release agent can also help.
Hope this will help,
TD
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Does someone have experience of cleaning cured phenolic resin? Is there some stripping agent available? Thanks!
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Crosslinked resins are hard to remove. You can use N-methylpyrrolidone to swell the polymer and scratch off. Sometimes cookiing in sodiumhydroxide solution helps. If the material contaminated is resistant against it use sulfuric acid / hydrogenperoxide. I any case use good protection when using those chemicals.
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I need to formulate Ni-current collector for screen-printing application. In this formulation binder must be compatible with positive material (resist to a potential of 4V in presence of electrolyte). Any idea of the resin/solvent that I can use as a binder? thank you in advance
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Thank you
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What additive to bismaleimide resins could most effectively improve the impact strength of the entire composition ???
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One strategy is to use thermoplastic materials as impact modifiers. Polyetherimide and polyarylenetherketone are used in most cases, but also ABS if it is possible to sacrify some of the heat stability. New would be to used polyphenylene ether (PPE or PPO) as additive. For adding a thermoplastic material it is advantageously if it is soluble in DMF or NMP to be mixed with the solution of BMI and o,o-diallyl-BPA. But perhaps also PPS powder can be used if the curing temperature is raised in a last step over the melting point of PPS (270°C). Another strategy is to broaden the network. Many work was done to make bismaleinimides with more aromatic rings between the both bismaleinimide groups. This strategie is also possible with the diallylbisphenol if e.g. CAS[128481-70-9] is used (3-nucleus o,o-diallyl bisphenol ). Also monofunctional monomers like phenylmaleinimide, o-allylphenol, eugenol, n-vinyl imidazole, n-vinyl pyrrolidone, vinylpyridine or styrene can braoden the network (under sacrifying some of the Tg).
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composite materials
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Dear  Asyraf Shahrom, your Suggestion depends very much on the temperature Level you are talking about. The polymer matrices you are discussing for this application do not withstand higher temperature Levels of 200 to 250°C and their mechanical strength Drops significantly and degrades beyond glass transsition temperature. For natural fiber materials the Situation is somewhat similar. So what are the conditions and what exactly you plan to do? Any more Details?
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I tried making composite out of Araldite CY-230 epoxy and HY-951 hardener. But it is remaining in gel form and not solidifying. What may be the possible reason?
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I am agree with Leonid V. Vladimirov in opinion that step adding of hardener allow us to improve of solidification process. At whole, the careful mixing of enough viscous epoxy resin with relatively small portion of hardener is a very important. The reasonable heating of epoxy resin aimed on reducing of viscosity before mixing is seemed useful too.   
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Higher pot life while mixing with hardener..
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The longest pot life have epoxy resins with anhydride hardeners like methyltetrahydro phthalic anhydride. Polyamide and polyaminoamides have shorter pot lifes, followed by aromatic amines, cycloaliphatic amines (mostly used IPDA) and aliphatic amines, like TETA (triethylene tetramine) with the shortest pot lifes. Special hardener are activated by high temperatures and have a long pot life for this reason. Dicyandiamide is such a latent hardener as well as micro encapsulated amine curing reagents.
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I am trying to determine the constituents of the wax-based coating of a paper bag for my study. I have contacted the manufacturer who will only give me "some" components which were: Emulsion Acrylic Co-polymer, Melamine Resin, Petroleum Resin, and Paraffin Wax.
But a brand new bag has a strong odour, indicating the use of VOCs.
Does anyone have any idea then what would be the standard chemicals used to make such a coating to be applied to a paper bag? And if so, any idea on the % quantities?
A shot in the dark, hopefully someone has some kind of info.
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Thanks Dr. Shcherbakov -- I can try those. I had viewed some patents but they were a bit too detailed into the manufacturing process, far out of my realm of experience. Perhaps those will be more suitable.
Thank you,
Geoff 
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How can I built up a test plan for process qualification for a composite manufacturer.
Can someone could provide me with a traveler specimen test plan?
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Dear Marc Alex Nana;
Your answer is somehow general; meaning that you need to clarify what kinds of detail your are looking for.
In common, for composite manufacturing and applying tests to your produced materials, mechanical tests such as compression, tensile, and bending are concerned. After molding and preparing your specimens, you need to investigate the mechanical behaviors of your samples. for this, you need the tensile tester (such as Zwick or Instron Universal tester) for study the behavior of your samples under uni-axial loading conditions. Or, you need to employ compression and three-point bending tester for analyzing the compress-ability and or rigidity of the samples. 
Moreover, the condition of molding including the applied presser of molds, the temperature, rate of the resin transferring, rate of cure operation, and etc must be under consideration if the process condition effects on the sample characteristics is of your main concerns.
Please also consider the attached files. I wish the attachments would be he helpful.
With the best regards;
Sanaz Hassanzadeh
PhD student at Textile Engineering;
Isfahan University of Technology, IRAN.
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how can I improve fiber composite material and use which resin is best 
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Aerospace is one of the largest and one of the most important markets for composites industry.  both in commercial and military aircraft  as well as space craft they all make substantial use of composites (for interior and outside).
they use wide variety of fibers; aramids, carbon fiber, glass fiber, and natural fibers. I know that Boeing has started using flax fiber for the interior of their aircraft for several years now. I do not know any other particular use of natural fibers in aerospace, but i am sure there are some other applications.
I think as far as hybridization, natural fibers like flax, jute, hemp and kenaf have a great use in automotive industry.
I have attached a useful document that can give you some general idea of composite use in aerospace.
It is by Dr. Smith - Avalon Co.
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Do they use milling machines? sinterization?
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Arc-evaporation (This vaporized material condenses on a substrate to form desired structures. The rate of nanotube synthesis by this method is quite high with deposition
rates of typically 20-100 mg/min)
Chemical vapour deposition (CVD): This method consists of producing carbon in gaseous phase and using an energy source such as plasma or a resistively heated furnace to transfer energy to gaseous carbon containing molecules and passing the gases through metal catalysts.
Laser vaporization:In this method a furnace is heated and an inert gas is made to flow through a tube at a constant pressure. A doped cylindrical graphite target is mounted at the center of the furnace. Vaporization of the target is performed by pulsed laser.
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Hello,
Recently I am fabricating PEEK composite films, so I try to cast pure PEEK film firstly.
I bought PEEK pellets. I try to dissolve PEEK in DMAC, but it can’t be dissolved. I once succeed dissolving PVDF and PMMA in DMAC, and cast to films. But it doesn't work for PEEK.
I have searched from the internet, someone said the only solvent that may be able to dissolve PEEK is concentrated sulfuric acid through a sulfonation reaction. My target is to prepare the PEEK films, it’s difficult and dangerous to volatilize the solvent. Is any safe and easy method to dissolve PEEK pellets and fabricate films?
Any suggestion will be appreciated.
Bingcheng Luo
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