Sol Molecular Weight Research Articles

Effect of Polymerized Rosin on Polymer Microstructure and Adhesive Properties in Tackified Acrylate Emulsions

The polyacrylate emulsions tackified by polymerized rosin were prepared via seeded semicontinous emulsion polymerization. The effects of polymerized rosin on the monomer conversion, particle size, polymer microstructure (gel fraction, cross-linking density and sol molecular weight) and adhesive properties were studied. The instantaneous conversion, gel fraction, cross-linking density and sol molecular weight decreased significantly due to the chain transfer and inhibition of the abietic acid. Also, the related mechanism was discussed. Dynamic light scattering was used to monitor the particle size of tackified emulsion. The relationship between the main adhesive properties of tackified latex films and polymer microstrcuture was studied.

Preparation and characterization of polyacrylate/polymerized rosin composite emulsions by seeded semicontinuous emulsion polymerization

AbstractPolyacrylate/polymerized rosin composite emulsions were prepared by seeded semicontinuous emulsion polymerization of acrylate monomers in which polymerized rosin was dissolved. The effects of polymerized rosin content on the polymerization stability, monomer conversion, polymer structure, and adhesive properties were studied. Polyacrylate/polymerized rosin composites were characterized by gel permeation chromatograph (GPC), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and thermogracvimetry (TG). The results showed that with an increase of polymerized rosin content from 0 to 6 wt %, gel fraction and sol molecular weight decreased obviously but monomer conversion was basically unchanged. In contrast, with a further increase of polymerized rosin content, the decreasing rates of gel fraction, and sol molecular weight were slowed down. Meanwhile, monomer conversion decreased remarkably. Moreover, interface failure changed into cohesive failure after the addition of polymerized rosin, and the peel adhesion and shear resistance of composite latex films declined with the increase of polymerized rosin content. Thermal analysis showed that polymerized rosin and polyacrylate were compatible and the composite latex films had good thermal stability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Modeling the Microstructure of Acrylic‐Polyurethane Hybrid Polymers Synthesized by Miniemulsion Polymerization

AbstractA computer simulation is presented for the prediction of the detailed microstructure of acrylic‐polyurethane hybrid polymers synthesized by miniemulsion polymerization. The simulation considers the polymerization of a mixture of acrylic monomers, one of them having a hydroxyl group, in the presence of a diisocyanate terminated prepolymer and a diol. The simulation approach is able to reproduce the experimental tendency (gel content, sol molecular weight and swelling capability) and provide additional information that is not attainable otherwise, as the distribution of pendant PU chains and dangling acrylic chains and the loop size distribution of the hybrid network. The analysis of such complex structures opens the possibility of tuning the performance of crosslinked emulsion polymers by adjusting their microstructure.magnified image

Miniemulsion Polymerization of 2-Ethylhexyl Acrylate. Polymer Architecture Control and Adhesion Properties

The feasibility of independent control of the gel fraction and sol molecular weight distribution in the miniemulsion polymerization of 2-ethylhexyl acrylate using symmetrical and nonsymmetrical cross-linkers and a chain transfer agent was investigated. It was found that the very reactive symmetrical cross-linker had only a limited effect on polymer architecture, whereas the nonsymmetrical cross-linker and the chain transfer agent had a profound effect allowing decoupling gel and sol molecular weight. Adhesive properties were mainly controlled by the gel content of the polymer.

Improving adhesion of acrylic waterborne PSAs to low surface energy materials: Introduction of stearyl acrylate

AbstractThe effect of incorporating stearyl acrylate (SA) in the polymer backbone of a pressure sensitive adhesive on its adhesion properties on low energy surfaces was investigated. The presence of SA did not affect the polymer microstructure (sol molecular weight, gel, and network density) but affected the compatibility with the low energy substrate and the elasticity of the adhesive. The combination of these effects resulted in an optimum SA content. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Influence of Particle Nucleation in Pressure Sensitive Adhesive Properties: Miniemulsion versus Emulsion Polymerization

AbstractMiniemulsion polymerization is a promising approach to produce and tailor pressure sensitive adhesives (PSAs). In this paper, a systematic comparison of the adhesive properties of latexes produced by miniemulsion and conventional emulsion polymerization is presented. Specifically, the influence of the total surfactant concentration, chain transfer agent concentration and chemical composition on the final adhesive properties of the polymer 2‐ethyl hexyl acrylate/methyl methacrylate/acrylic acid was discerned using a 23 factorial design for each polymerization method. In addition to the adhesive properties (i.e., loop tack, peel strength and shear strength), molecular weight distribution, particle size distribution (PSD) and glass transition temperature were analyzed. The results show that under the conditions used in this work, it is possible to produce PSAs using miniemulsion polymerization, a process wherein monomer droplet nucleation is the dominant particle nucleation mechanism. The use of a miniemulsion polymerization process, as opposed to the conventional emulsion technique, produced several differences such as larger particles sizes and narrower molecular weight distributions. Focusing on the PSA films that exhibited adhesive rather than cohesive failure, the PSA films generated via miniemulsion polymerization displayed higher values of loop tack and peel strength compared to those produced via conventional emulsion polymerization. Shear strength results were strongly dependent on the amount of gel content and sol molecular weight for both cases.

(Mini)emulsion Polymerization: Effect of the Segregation Degree on Polymer Architecture

A continuous loop reactor was used for the production of 2-ethylhexyl acrylate (2-EHA), methyl methacrylate (MMA) and acrylic acid (AA) pressure sensitive adhesive by both emulsion and miniemulsion polymerization. Similar high monomer conversions were achieved in both processes, but striking differences in polymer architecture were found. A mathematical model was used to analyze these differences concluding that because the costabilizer suppressed monomer diffusion from miniemulsion droplets, the average polymer concentration in the polymerization loci was lower in the miniemulsion process. This resulted in less chain transfer to polymer, and hence in lower sol molecular weight and gel content.

Effect of the Diacrylate Ester Size on the Semicontinuous Cross-Linking Emulsion Copolymerization of BA

The seeded semicontinuous emulsion copolymerization of butyl acrylate (BA) with a series of diacrylate cross-linkers at 80 °C and using potassium persulfate as initiator was investigated. The influence of the diacrylate ester size on the kinetics, branching and cross-linking density, molecular weight between entanglements, gel fraction, sol molecular weight, and mechanical properties (glass transition temperature and storage modulus) was investigated. It was found that the shorter the diacrylate, the less cross-linked the polymer and the lower the glass transition temperature and the storage modulus. This effect was explained by a higher cyclization rate of the shorter diacrylates due to energetically favored cycle formation.

Seeded Semicontinuous Emulsion Copolymerization of Butyl Acrylate with Cross-Linkers

The seeded semicontinuous emulsion copolymerization of butyl acrylate (BA) with divinyl monomers (butanediol diacrylate, BDA, and allyl methacrylate, AMA), at 80 °C and using potassium persulfate as initiator was investigated. Particularly, the study of the influence of the type and amount of cross-linkers on the kinetics, level of branching, cross-linking density, gel fraction, sol molecular weight, and latex film mechanical properties (i.e., glass transition temperature, Tg, storage modulus, and molecular weight between entanglements, Me) produced during the polymerizations was considered. The results showed that the most reactive cross-linker, BDA, produced the less cross-linked, branched, and gel-containing polymer. Mechanical property data confirmed this unexpected trend as the copolymer made with BDA exhibited the weakest mechanical properties. These results were explained by the higher occurrence of primary cyclization reactions in the case of BDA.

Seeded Semibatch Emulsion Copolymerization of n-Butyl Acrylate and Methyl Methacrylate

The kinetics and polymer microstructure of the seeded semibatch emulsion copolymerization of n-BA/MMA were investigated in this work. Free monomer concentration was determined on-line by means of FT-Raman spectrosocopy. The kinetics, gel fraction, and molecular weight distribution were determined for several semibatch reactions of different monomer composition. The experiments show that, when the amount of MMA in the recipe was increased (from 90/10 to 50/50 n-BA/MMA by moles), the instantaneous conversion increased, whereas the gel content decreased and the sol molecular weight exhibited no defined trend. A mathematical model was used to analyze the experimental data.

Modeling of Seeded Semibatch Emulsion Polymerization of n-BA

A mathematical model for the computation of kinetics, branching frequency, sol molecular weight distribution, and gel fraction for the seeded semicontinuous emulsion polymerization of n-BA is presented. The model incorporates mechanistic features that have been found to play an important role in the polymerization of n-BA, such as the intramolecular transfer to polymer, so-called backbiting, and the low reactivity of the tertiary radicals resulting from such a reaction. Model parameters for which values are not available in the literature were obtained by fitting the model predictions to the kinetic data and structural properties of the polymer (fraction of gel, sol molecular weight distribution, and level of branches) gathered in seeded semicontinuous emulsion polymerizations of n-BA carried out at 75 °C with potassium persulfate as the initiator. The model fits all of these experimental data quite well.

Seeded semibatch emulsion polymerization of butyl acrylate: Effect of the chain-transfer agent on the kinetics and structural properties

The effect of dodecane-1-thiol on the kinetics, gel fraction, level of branches, and sol molecular weight distribution of the seeded semibatch emulsion polymerization of n-butyl acrylate carried out at 75 °C was investigated. The gel fraction was strongly affected by the content of the chain-transfer agent (CTA). The sol weight-average molecular weights decreased with increasing CTA concentration, whereas no effect on the kinetics and the level of branches was observed. The experimental data were analyzed with a mathematical model of the process that was able to catch fairly well the effect of the process variable. In addition, adhesive tests were carried out to check the effect of the gel fraction on the adhesive properties. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1106–1119, 2001

Modeling Gelation and Sol Molecular Weight Distribution in Emulsion Polymerization

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTModeling Gelation and Sol Molecular Weight Distribution in Emulsion PolymerizationGurutze Arzamendi and Jose M. AsuaCite this: Macromolecules 1995, 28, 22, 7479–7490Publication Date (Print):October 1, 1995Publication History Published online1 May 2002Published inissue 1 October 1995https://doi.org/10.1021/ma00126a028RIGHTS & PERMISSIONSArticle Views291Altmetric-Citations62LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts Get e-Alerts

Polymerization beyond the gel point. I. The molecular weight of sol as a function of the extent of reaction

AbstractTheoretical expressions for describing the weight‐average molecular weights of the soluble fractions from polymerizations obtained beyond the gel point were tested experimentally. The theory of branching processes and a recursive approach essentially based on the method of Macosko and Miller were found to be virtually equivalent. The soluble fractions produced from the stoichiometric polymerization of 1,3,5‐benzenetriacetic acid (BTA) with decamethylene glycol (DMG) gave molecular weights and distributions in excellent qualitative agreement with the theory. The results are interpreted in terms of intramolecular cyclization, diffusion, and the presence of microgel particles.

Molecular Structure and Macroscopic Properties of Synthetic Cis-Poly(Isoprene)

Abstract By changing the sol-gel ratio and the structure of the gel fraction it is possible to obtain various grades of synthetic cis-poly(isoprene) which show promise for different applications in the tire and mechanical rubber goods industries. The processability of commercial SKI-3 rubber (at a given average molecular weight of sol) depends mainly on the structure of the gel fraction. Thus, for example, inferior processing properties of rubber compounds is associated primarily with the presence of tight gel. The content and structure of the gel fraction also significantly affect plasto-elastic properties of raw rubbers, e.g. a low plasticity of raw rubbers owes to the increased content of gel fraction. The reduced green strength of compounds based on SKI—3 rubber is accounted for by its chemical structure. Conventional methods used to change the properties of rubbers (including the variation in molecular weight, molecular weight distribution, branching degree, and variation in the content and structure of gel fraction) cannot be considered to be adequate to tackle the problem of the green strength of SKI—3 black stocks. The way to solve the problem appears to be the introduction of functional groups into the polymer chain at the stage of synthesis or processing. These functional groups should be active as to the formation of labile rubber—carbon black—rubber and/or rubber—rubber bonds. High purity of microstructure is necessary but not sufficient for obtaining the required level of green strength of compounded SKI—3. The gel fractions of SKI—3 rubber yield vulcanizates with a more dense network than the corresponding sol vulcanizates. The temperature dependence of the tensile strength is controlled by the network density of vulcanizates from high cis-1,4 poly(isoprene).

Molecular Weight of Sol and Gel in Crude Hevea Rubber

Molecular Weight of Sol and Gel in Crude Hevea Rubber

Molecular Weight of Sol and Gel in Crude Hevea Rubber.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular Weight of Sol and Gel in Crude Hevea Rubber.A. R. Kemp and H. PetersCite this: J. Phys. Chem. 1939, 43, 8, 1063–1082Publication Date (Print):August 1, 1939Publication History Published online1 May 2002Published inissue 1 August 1939https://doi.org/10.1021/j150395a009RIGHTS & PERMISSIONSArticle Views35Altmetric-Citations5LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (800 KB) Get e-Alerts