High conversion free‐radical suspension polymerization: End groups in poly(methyl methacrylate) and their influence on the thermal stability

Abstract

Suspension free‐radical polymerization of vinyl monomers, carried out in the presence of alkyl mercaptans as chain‐transfer agents, is analyzed. A model which accounts for the development with conversion of the polymer weight fractions having particularly tagged end groups, namely sulfur‐containing and unsaturated end groups, is presented. The best current theories for diffusion‐controlled polymerizations are included in the model. The sulfur content of poly(methyl methacrylate), determined as a function of conversion by a microcoulometric method, is in good agreement with the values predicted from polymerization kinetics. The rate of weight loss of the produced polymers is then related to the content of the unsaturated end groups. By comparing experimental thermal stability indexes (from thermogravimetry and isothermal heating experiments) to calculated polymer weight fractions, it is shown that the thermal stability of poly(methyl methacrylate) produced in the presence of alkyl mercaptans approximately depends on the square of the weight fraction of the polymer chains with an unsaturated end group.

Microwave polymerization of poly(methyl acrylate): Conversion studies at variable power

“…37,38 Reproducible data at the gel effect was therefore difficult To offset any change in these IR bands due to either the concentration of the sample or due to to obtain. This would be true for all reactions characterized by the gel effect, including MA.…”

Simulation of Free Radical Bulk/Solution Homopolymerization Using Mono- and Bi-functional Initiators

“…Despite the research effort on the measurement of the rate constant of propagation for MMA, experimental data on MMA homopolyrnerization in suspension up to high conversions are rare. In a previous paper (Gao and Penlidis, 1996) Agarwal and Gupta (1993) .simulation ofMMA solution polymerization Dua et al ( 1997) MMA bulk homopolymerization under nonisothermal conditions Giannetti et al (1986) MMA suspension homopolymerization with CTAs MMA, styrene and vinyl acetate homopolymerization in suspension Panke (1995) MMA bulk homopolymerization Ray et al (1995) Simulation ofMMA homopolymerization Seth and Gupta (1995/96) Simulation ofMMA homopolymerization Terra et al (1997b) Simulation ofMMA homopolymerization homopolymerization in suspension. Since the initiator used in suspension polymerization is oil soluble, the main locus of polymerization is in the monomer droplets, and therefore the kinetics of suspension polymerization can be considered to be similar to that of bulk polymerization.…”

Poly(vinyl acetate)/Silver Nanocomposite Microspheres Prepared by Suspension Polymerization at Low Temperature

“…Using suspension polymerization to prepare polymer‐silver nanoparticle composites is interesting in terms of an easy manipulation, low cost, and controllable particle size 22. It is well known that a range of variables, such as the type and amount of initiator and suspending agent, the polymerization temperature, the monomer to water ratio, and the agitation speed, affect the molecular weight of the polymer synthesized 22.…”