Abstract
The aim of this work was to synthesize copolymers of styrene (St) and butyl acrylate (AB) cross-linked with allyl methacrylate by semicontinuous heterogeneous polymerization in order to study the mechanical properties of the polymeric films prepared from the latexes obtained. Copolymer latexes were stable and nanoparticles with spherical morphology were observed by Transmission Electron Microscopy (TEM). The latexes had final conversions between 92,5 and 97,0%, which were determined by the gravimetric method, and a solids content close to 20%. The nanoparticles of latex had an average diameter of 59,1; 55,1 and 49,0 nm for monomer dosing rates of 0,75; 0,45 and 0,15 g/min, respectively. By means of mechanical characterization of the polymeric films and according to the statistical analysis, it was found that when the monomer dosage rate decreased in the synthesis, the mean particle diameter and molecular weight also decreased, and with it a decrease in its Young's Modulus (MPa).
Highlights
In the last years, interest in obtaining new materials with better mechanical characteristics and properties than those of the materials already known has increased in order to satisfy the modern technology needs
MechanicCaol pchoalyramcteerizSaytinotnhoefspisolymeric films based on copolymers of styrene and butyl acrylate obtained... 73 Figure 2 shows the instantaneous conversion curve (Xi) against normalized time defined as the relationshRipEoSfUsaLmTpSlinAgNtiDmeDwISitCh UreSspSeIcOt tNoStotal addition time, for the semicontinuous polymerization process of styrene and butyl acrylate
The instantaneous conversion is the monomer fraction added to time tr that is converted to a polymer, since the global conversion is the toFtiaglumreo2noamlsoersfhroawctsiothnaat dthdeedinisntatnhteanperooucsescsonthveartshioans irnecarcetaesdesonqutiicmkleytra.nd reaches Figure h2igahlsvoalushesowatsretlhaatitvethlyesihnosrttatnimtaense(otru i0n,3c;rethaeseinssqtaunitcaknleyouasncdonrveearcshioens high values aintcrreelaasteisvevleyryshsolrotwtilymeasnd(trrero0u,g3h; tahlel itnhestarneatactnioeno.usIncoandvdietriosino,nsiinnccereases very slostwyrleyneanadndrebmutayilnascrhyilgahte thharvoeugahloawllstohleubrieliatyctiinonw.aItner,adpodliytimoenr,izsaintiocen isstycraernriedanoudt butyl acrylatethrhoauvgeh ma icleolwlar snoulculebailtiiotyn, iinnstweaadteorf, hpoomloygmeneeriozuastinouncleiasticoanr.ried out through micellar nucleation, instead of homogeneous nucleation
Summary
Interest in obtaining new materials with better mechanical characteristics and properties than those of the materials already known has increased in order to satisfy the modern technology needs. Among the materials of great interest are the polymeric materials, and to obtain them there are many polymerization techniques, for instance: emulsion and microemulsion polymerization, which have many advantages over other polymerization techniques These advantages include: better control of reaction temperature, high rates of reaction, higher molecular weights (> 1 x 106 g/mol), possibility to control the molecular weight (using chain transfer agents), low viscosity latex and elimination of environmental pollution risks[1,2]. One of the drawbacks of microemulsion polymerization are the high concentrations of surfactant used and the low polymer/surfactant ratio in the final latex. These authors reported an increase in the polymer/surfactant ratio of up to 3/1. This ratio was improved up to 10/13,4
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