Preparation and characterization of nanocomposites of natural rubber with polystyrene and styrene-methacrylic acid copolymer nanoparticles

Composites of natural rubber (NR)/vinyl polymer nanoparticles as polystyrene (PS) and poly(styrenemethacrylic acid) (P(S-MAA)) were prepared by heterocoagulation technique. The polymer nanoparticles were prepared by emulsifier-free emulsion polymerizations at 70°C using potassium persulfate as initiator. Under acidic condition where positive charge was present on the NR latex (NRL) surface, the nanoparticles having negative charge mainly from sulfate group of initiator were able to adsorb on the NRL surface, the electrostatic interaction being the driving force. The scanning electron micrographs showed that the polymer nanoparticles are homogenously distributed throughout NR matrix as nanoclusters with an average size of about 500 and 200 nm for PS and P(S-MAA), respectively. The mechanical properties of NR/PS and NR/P(S-MAA) composite films were compared with the NR host. The nanocomposites, particularly when the polymer nanoparticles are uniformly dispersed, possess significantly enhanced mechanical properties strongly depending on the morphology of the nanocomposites

Preparation of polydivinylbenzene/natural rubber capsule encapsulating octadecane: Influence of natural rubber molecular weight and content

The encapsulation of octadecane (OD) as heat storage material was studied. The core-shell polydivinylbenzene (PDVB)/natural rubber (NR) capsules encapsulating OD was prepared using the Self-assembling of Phase Separated Polymer (SaPSeP) method by suspension polymerization. The mixture of dispersed phase consisting of DVB, NR, OD and benzoyl peroxide was added in polyvinyl alcohol aqueous solution and then homogenized at 5,000 rpm for 5 minutes. The obtained monomer droplet emulsion was subsequently polymerized at 80°C for 8 hours resulting in PDVB/NR capsule encapsulating OD. The influence of molecular weight and content of NR on the encapsulation efficiency and thermal properties of the encapsulated OD were investigated. It was found that both factors affected on the preparation of PDVB/NR/OD capsule. High molecular weight NR restricted phase separation of formed PDVB. High NR content also reduced phase separation of PDVB due to the increase of internal viscosity. Then, only the incorporation of appropriate molecular weight and content of NR resulted in the formation of PDVB/NR/OD capsule