Composite Resins - Science topic

yes, the surface roughness of direct resin composite restorations is both material and polisher-dependent.

Material Factors:

Polisher Factors:

Smooth surfaces improve aesthetics, reduce plaque retention, and enhance restoration longevity. Material choice and polishing system are key to achieving optimal results.

During the last several years, more polishable nano filled composite resins have become available with the physical properties of hybrid composite resins. With these new composites have come new polishing sy tems to include rubberized abrasives. Many of the instruments previously used to finish composite res ins are still very useful with the newer composites. In order to attain the optimal finish for composite resins, it is important to follow manufacturer’s recommenda tions. Using a systematic technique from finishing burs and diamonds, abrasive disks, rubberized abrasives and composite resin polishing paste, you should be able to impart an enamel-like luster to your composite resins.

Specific mechanical properties of Tera Harz TC-80DP, a maxillofacial material, might not be readily available in public domain sources or scientific literature. The mechanical properties of maxillofacial materials can vary depending on factors such as composition, manufacturing process, and intended application.

Tera Harz TC-80DP is a type of thermosetting acrylic resin commonly used in the fabrication of facial prostheses, such as nasal and auricular prostheses. While the manufacturer may provide information on its mechanical properties, such as tensile strength, flexural strength, and hardness, this data may not always be publicly accessible.

May be the device didn't work.

If it is applicable try another FTIR device

FT-IR spectra of the material before and after the cure reaction were taken and the ratio of heights between absorptions at 1637cm−1 (variable) and 1610cm−(reference)

Yes, dissolving Rubber in toluene is also used in industry, to make coated fabrics. There are some applications where NBR and EPDM rubbers are dissolved and spreaded onto various substrates. Also CR is sometimes dissolved ti obtain adhesives.

There are no particular parameters to be considered in the Lab, dissolving is made at room temperature, and viscosity Is kept at around 20k or 50k cps, in order to have enough material to be deposited and viscosity high enough to allow proper mixing and even distribution of all ingredients.

About the films, It Is complicated to not make them stick to each other, even after curing. Try to increase their thickness, which would make them easier to handle, or cover them with an antitack agent

Respected sir , please state the problem, in paragraph so that i can answer

Delamination of laminates in a honeycomb composite structure can occur when there is a failure of the bond between the layers of the composite, resulting in the separation of the layers. In a simple supported structure under bending stress, the forces acting on the structure can cause the layers of the composite to experience different levels of tension and compression, which can lead to the development of shear stresses at the interface between the layers. These shear stresses can cause the bond between the layers to fail, resulting in delamination.

Your thinking that the developed tension on the bottom skin of the honeycomb composite structure can act as the main peeling force causing delamination is generally correct. The tension in the bottom skin can cause the bond between the layers to be subjected to tensile forces, which can lead to the separation of the layers if the bond is not strong enough to resist the forces.

However, it is important to note that the delamination of laminates in a honeycomb composite structure can also be influenced by other factors, such as the properties of the materials used to make the composite, the manufacturing process used to produce the composite, and the loading conditions applied to the composite. It is therefore important to carefully consider all of these factors when evaluating the risk of delamination in a composite structure.

Cashew Nut Shell Liquid - an overview | ScienceDirect Topics

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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

Aidin Mirzapour You can refer to the following doi

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).

What is the polymer molecular weight?? because it is an influential factor in the preparation of the membrane?

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:

1) https://www.shinetsusilicone-global.com/catalog/pdf/rubber_e.pdf

2) https://www.dow.com/en-us/product-technology/pt-silicone-hybrids-silanes.html

Best regards.

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

Dear Azaz,

Literature may be useful to you;

Bestoon Faraj Wonderful question and i do agree with the expert views

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.

several restorative material and approach available, case and protocol might have a major role and minor role for the operator preference.

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.

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

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.

Dear all, the following documents deal with graphene composites preparation conditions and characterization theirafter. My Regards

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.

I think N-Methyl-2-pyrrolidone (NMP) is proper solvent for dispersing PPy and PANI powder.

Dear Widad Al-Omairi

Please see the linked document. It shows how many passages are recommended or acceptable in the laboratory.

Regards,

Mario

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.

the best ratio is Resin:fibre=40 vol%:60vol.%

The most dental ceramics preferred to restore dental implants are monolithic zirconia, lithium disilicate, zirconia layered with felspathic.

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?

Good question

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

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.

Sanaa Ibrahim How frequesntly should I change culture media then (DMEM = 10% FBS)?

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.

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

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.

YOU HAVE TO RESPECT THE CROSSLINKING TEMPERATURE(gelification and vitrification temperature)

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.

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

like aceton

viscosity test

Hi Amin,

Thank you for your answer :) 

Kinds,

Zeynep

of course, you can use many composite using natural fibres etc

Hi,

I think PVDF should be good..another polymer we looked at is polyurathene..wat do you think?

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. 

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...

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. 

Via the link below you will see some measuring methods. Sample weight can also be an alternative for thickness.

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.

Araldite is good resin for bonding.

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,

Hello Marcela Escobar

please check the pdfs related to your topic

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.  

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.

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

Dear Marcelo, give a look to epoxidized vegetable oils. Probably you can find some not expensive. Regards

Dear Nawras,

check this:

best regards

Johannes

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.

I only know HF.

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. 

We use the fiber glass fabric impregnated with glue, instead of ready plastic and the problem of qualitative samples is removed

 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

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.

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.

For Phenol farmeldahyde resins availability in Pakistan the detail can be find out from Gaffor Chemicals. The detail information is available online.

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

 please check it

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.

Thank you

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).

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?

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.   

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.