A Methodology Towards Mechanical Properties Optimization of Three-Component Polymers by the Gradual Variation of Feed Composition in Semi-Continuous Emulsion-Free Radical Polymerization

Abstract

In this work, a new methodology for the synthesis of three-component polymers (TCPs) was developed using a seeded, semi-continuous free-radical emulsion polymerization towards the optimization of the moduli–ultimate deformation performance and energy dissipation capacity for a styrene (S), n-butyl acrylate (BA), and 4-vinylbenzyl chloride (VBC) system. The three components were sequentially fed in pairs, varying feed composition along the conversion using S as the common monomer. To prepare a reference material, an industrial method was utilized with those monomers, using an equivalent global composition in a two-stage batch process (TS). Nanophase formation in the particles was observed by transmission electron microscopy (TEM), while the separation of the phases in the solid samples was observed by atomic force microscopy (AFM). The changes in glass transition temperature were determined by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The latter was primarily used to compare mechanodynamic properties as a function of temperature for the two synthesis methods used. Thus, the higher toughness of the forced composition three-component polymeric materials was evaluated by means of their energy dissipation capacity, toughness, and stress–strain measurements at several temperatures.

Redox initiation in semicontinuous polymerization to search for specific mechanical properties of copolymers

“…Regarding properties synergism for the "A" and "B" components, it has been accomplished in polymer systems of two and three components, achieving their interaction at micro or nanolevel (10,18). The gradual change in polymer composition along the reaction promoted the formation of a polymer bulk of chains with rich domains of each component and allowed the strong interactions toward properties optimization.…”

“…Nevertheless, FCC synthesis has been performed using thermal decomposition initiators at 70°C, to get a convenient radicals generation rate, and be able to maintain an adequate polymerization rate for moderate or long reaction times (4-12 h), to then avoid an excessive monomer accumulation in the polymerization locus (18)(19)(20). This initiation mode usually requires long times for the polymerization process, which involves high energy costs.…”