Polymerization kinetics of styrene in isotactic polypropylene pellets and evolution of phase morphology during polymerization

Abstract

Polymerization kinetics of styrene (St) in commercially available isotactic polypropylene (iPP) pellets and the phase morphology evolution during polymerization are investigated. The polymerization rate of St in iPP pellets is slightly faster than in the corresponding bulk and suspension polymerizations carried out under similar reaction conditions due to the existence of two reaction sites: amorphous PP and polystyrene (PS), which are formed by polymerization-induced phase separation. Two mechanisms are proposed for the phase morphology evolution: nucleation and growth, and St-assisted coarsening of phase structure. During polymerization, the size of the dispersed PS particles increases with polymerization time no matter at which position of the pellet, but the increasing amplitude is much bigger at 200 lm distance to the edge than at the center due to much more significant occurrence of St-assisted coarsening of phase structure which is attributed to both high values of PS/PP and St/PP resulted from polymerizationinduced diffusion of St.

Preparation of polyamide 6/polystyrene quasi‐nanoblends by diffusion and subsequent polymerization of styrene in water‐sorbed polyamide 6 pellets

“…This confirms that BPO is indeed diffused into the pellets along the diffusion paths of styrene and BPO/styrene ratio is almost constant, independent of the amount of styrene existing in the pellets. The M w is in the same order of magnitude as that of PS in PP/PS quasi‐nanoblend pellets synthesized previously . Although the diffusion medium is different in the preparation procedure of the two types of blends, the polymerization procedures are similar.…”

“…Initially, the preparation procedure for PP/PS quasi‐nanoblends was tested with the as‐received commercial PA6 pellets. It consists of two steps: (1) diffusion of styrene at 90 °C for 3 h in water and (2) polymerization at 90 °C for 3 h after separating and transferring the pellets into a new flask containing water.…”

“…Diffusion and subsequent polymerization of a monomer (or monomer mixture) in commercial polymer pellets is a solid‐state method reported by our research group to prepare quasi‐nanoblend pellets directly applicable for low shear processing such as injection molding without the need for precompounding . Low polarity monomers such as styrene, butyl methacrylate (BMA), and their mixtures have been successfully diffused into the amorphous regions of nonpolar polymer pellets such as iPP, and quasi‐nanoblends such as PP/PS nanoblends with improved mechanical properties have been formed upon polymerization of the monomer due to the confinement of the amorphous PP chains and the surrounded PP lamellae.…”

Fabrication of LDPE/PS interpolymer resin particles through a swelling suspension polymerization approach

“…The MW of the particles decreased with increasing BPO content. The concentration of free radical increased with increasing initiator content, thus triggering more monomers to polymerize (19,20). With increasing free radical concentration, the polymerization rate also increased.…”

Morphology and Mechanical Properties of Polyamide 6/Polystyrene Blends Prepared by Diffusion and Subsequent Polymerization of Styrene in Polyamide 6 Pellets

“…Therefore, reducing the size of the dispersed phase of polymer blends is a very interesting topic in polymer science. Diffusion and subsequent polymerization of a monomer (or monomer mixture) in commercial polymer pellets is a method that has been explored in recent years by our research group for preparing polymer blend pellets with fine particle sizes down to the quasi-nanoscale [ 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. It involves diffusion of a monomer (typically styrene) into the amorphous regions of semicrystalline polymer pellets and subsequent diffusion of an initiator (typically benzoyl peroxide) along the diffusion paths of the monomer.…”