Heterocoagulation of polychloroprene on natural rubber latex particles for use in the preparation of toughened polystyrene

Abstract

ABSTRACT:The toughness of high-impact polystyrene based on ␥-radiation-vulcanized natural rubber (NR) was effectively enhanced by the addition of a block copolymer at the NR/polystyrene interface. An NR/polychloroprene (CR) composite latex particle was produced by the heterocoagulation technique for its use as a model in a compatibilization study. A nonionic surfactant (Tween 80), whose molecule bore poly(ethylene oxide) (PEO), was adsorbed onto the CR particle and allowed to form a complex between PEO and an indigenous surfactant (protein-lipid) on the NR particle surface. The presence of CR-Tween on the outer layer of the obtained composite polymer particle was characterized by the particle size, potential, and glass-transition temperature. That the film cast from the heterocoagulated latex showed better oil resistance than the NR film confirmed the NR/CR core-shell structure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 9 -13, 2003

Composite natural rubber based latex particles: a novel approach

“…Characterisation of NR, CR and skim latices [17][18][19] The particle size distribution curves of the NR, CR and skim latices are shown in Fig. 1.…”

“…In the case of CR latex, the zeta potential showed a negative value over a range of pH, which indicated the presence of a negative charge possibly derived from the anionic surfactant on the CR particle surface. [17,18] The adsorption of Tween 80 (6% by weight) on CR particle surface was indicated by the decrease in the absolute value of zeta potential at pH w7 of CR-Tween latex (K35 mV) when compared to that of the original one (w52 mV) as indicated in Fig. 3.…”

“…5. DSC thermograms of films casted from NR, CR and heterocoagulated latices [17,18]. due to the intermolecular interaction between polar groups in ENR chains [10] as displayed in Fig.…”

“…Zeta potential of particles in the latices was determined by using a microelectrophoresis apparatus (Zetasizer 4, Malvern) at 30 8C after adjusting the pH by addition of an aqueous solution (0.1 M) of hydrochloric acid (Merck, GR) or sodium hydroxide (Merck, GR). [17,18] Tween 80, polyoxyethylene sorbitan monooleate, (Fluka, practical) (6% by weight of dry latex) was adsorbed onto the CR latex prior to mixing a known amount of the CR-Tween having 1% total solid content (TSC) with the NR latex (1%TSC, 10 g) at pH w2 in an Erlenmeyer flask at room temperature. The blending ratio was determined from the theoretical number (N max ) of shell particles required to form a close-packed particulate monolayer on a core particle, calculated by using the equation previously reported [20,21].…”

“…The NR/CR composite latex particle was then used as a model in the further study of replacing CR by ENR, crosslinked ENR, and/or skim NR latices in the heterocoagulation technique. [17][18][19] Particle size distribution of concentrated high ammonia preserved NR latex (N.Y. Rubber Co., Ltd, Thailand) was measured by using a particle size analyser (Mastersizer S, Malvern) while photon correlation spectroscopy (Autosizer S4700, Malvern) was used in the case of the CR (Neoprene 671A, DuPont) and skim (Rayong Bangkok Rubber Co., Ltd, Thailand). Zeta potential of particles in the latices was determined by using a microelectrophoresis apparatus (Zetasizer 4, Malvern) at 30 8C after adjusting the pH by addition of an aqueous solution (0.1 M) of hydrochloric acid (Merck, GR) or sodium hydroxide (Merck, GR).…”