Semicontinuous emulsion copolymerization to obtain styrene–methyl acrylate copolymers with predetermined chemical composition distributions

Abstract

SYNOPSISFour types of emulsion copolymerization processes were applied to produce various styrenemethyl acrylate copolymer latices. (1) Batch emulsion copolymerization. ( 2 ) Monomer starved semicontinuous emulsion copolymerization, i.e., a monomer mixture of constant composition was fed to the reactor at a constant rate. Sufficiently low addition rates led to homogeneous copolymers. ( 3 ) Optimal addition rate profiles were used to produce homogeneous emulsion copolymers in relatively short times. The profiles were determined in a semiempirical way, and applied to three different copolymer compositions. ( 4 ) We made an attempt to determine an addition rate profile to produce a heterogeneous emulsion copolymer with predetermined heterogeneity, i.e., a copolymer of which the chemical composition distribution (CCD) did not consist of one narrow peak, as with homogeneous copolymers, but had a predetermined broadness profile. Strategies ( 2 ) and (3) were used to produce homogeneous emulsion copolymers with varying fractions of styrene. Strategy (3) was also used to demonstrate the influence of the monomer ratio on the kinetics. The advantage of this method is that the monomer ratio is constant over the whole conversion range in the latex particles. High performance liquid chromatography (HPLC) was used to determine the homogeneity/ heterogeneity of the copolymers produced, and proved to be invaluable in determining the optimal addition rate profile. The final goal will be to study the influence of the chemical composition distribution (CCD) on mechanical properties of these copolymers, as both homopolymers used in this study have quite differentglass transition temperatures; the results will be published later. 0 1993 John Wiley & Sons, Inc.

Thermoset Alkyd-Acrylic Hybrid Emulsions for Coatings

“…On subsequent storage, the larger particles led to fusion, agglomeration and early sedimentation. [6] FIG. 1.…”

“…[3] Synthesis and characterization of alkyd=acrylate hybrid latexes were discussed by many authors. [4][5][6][7] It is expected that in the ideal situation, the combination of alkyd resins and acrylic dispersions would result in a VOC free binder that dries faster and crosslinks (auto-oxidative) due to the presence of acrylics and alkyd resins respectively. In order to make alkyd resins water soluble, the first attempt made was to prepare alkyd resin with high acid values normally 40-60 mg KOH g. À1 Newly synthesized alkyd resins with higher acid values were of low molecular weights.…”

Novel urethane/acrylic hybrid emulsions for VOC compliant coatings

“…The performance of these materials is dependent on the nature of oil and diisocyante used. Linseed, sunflower, dehydrated castor and soybean oils frequently appear in the literature as the oil components of urethane oils (Schoonbrood et al , 1993; Wang et al , 1996; Overbeek et al , 2000). Alkyd resins are polyesters modified with unsaturated fatty acids.…”

A Comprehensive Experimental and Theoretical Investigation of the Styrene/2‐Ethylhexyl Acrylate Emulsion Copolymerization

“…However, during the copolymerization of the aforementioned monomers in batch reactors, the monomer composition changes continuously, leading to the formation of chemically heterogeneous products unless a suitable monomer addition policy is employed. To date, a plethora of papers have been published on styrene emulsion polymerization and/or its copolymerization with short chain acrylic esters [1][2][3][4][5][6][7][8][9][10] and with vinyl acetate. [11][12][13][14][15][16] On the other hand, the kinetic investigation of the emulsion polymerization of 2-ethylhexyl acrylate (2-EHA) has not received much attention, [17,18] and to our knowledge kinetic results on the styrene/2-EHA emulsion copolymerization, in the presence of a non-ionic surfactant, have not appeared in open literature.…”