Guang Lu

Preparation and Properties of Interpenetrating Polymer Network Films from Prevulcanized Natural Rubber Latex/Chitosan Blends

The acidfied sulfur-prevulcanized natural rubber (NR) latex was mixed with 1～20 parts per hundred rubber (phr) of a 2wt% solution of chitosan (CS) in 1wt% acetic acid, then cast to preapare a series of NR/CS semi-interpenetrating polymer network (semi-IPN) films; the NR/CS semi-IPN films were further treated with 0.5wt% glutaraldehyde（GA）solution for respectively 1, 3 and 6h to obtain NR/CS IPN films. The mechanical properties and swelling behavours in various media of water, toluene and reference olis of IRM901 and IRM 903 of these films were studied and compared with those pure sulfur-prevulcanized natural rubber latex (SNRL) film. Results showed that, NR/CS IPN films with better mechanical properties could be obained by treating the 24h-leached NR/CS semi-IPN films than by treating directly the unleached ones with 0.5wt% GA solution; the tear strength, 300% modulus, Shore A hardness, hydrophilicity and resistance to non-polar solvents and oil of the SNRL films increased with the incorporation of CS, while the NR/CS IPN films exhibited better than the NR/CS semi-IPN films, especially in tear strength enhancement; the tensile strength and elongation at break of NR/CS semi-IPN and IPN films gradually decreased with the increase in CS content. However, most of the elasticity of pure NR vulcanizate could be reserved, when the CS content was not greater than 15 phr.

Surface Modification of Natural Rubber Latex Film by N-Vinypyrrolidone Graft Copolymerization

The surface modification of natural rubber (NR) latex film by argon plasma pretreatment and subsequent UV-induced graft copolymerization of N-vinypyrrolidone (NVP) was carried out to improve the hydrophilic behavior. The effects of plasma pretreatment time and UV irradiation time on the graft yields were studied. The peroxide functionalities formed by the oxidations in air after plasma pretreatment are the activated species for the subsequent UV-induced graft copolymerization of NVP. ATR-FTIR and XPS analyses indicate that the PVP molecules have covalently bonded onto the surface of NR latex film. The argon plasma pretreatment time of 2min and UV irradiation time of 10min are the proper conditions for the graft polymerization of NVP onto NR latex film, which can reduce the water contact angle value of NR latex film from 95o to about 57o.

Thermal-Oxidative Aging Resistance and Water Absorption of Natural Rubber Latex/Methyl Methacrylate-Grafted-Natural Rubber Latex Blends

Abstract. The natural rubber latex (NRL) concentrate was mixed with 10～50 parts per hundred rubber (phr) of methyl methacrylate-grafted-natural rubber latex having a methyl methacrylate content of 49% (MGL49), prevulcanized, and then cast to obtain prevulcanized NRL/MGL49 films. The leached films of prevulcanized NRL/MGL49 were aged in an hot-air oven for comparison of the mechanical properties before and after aging, whereas the thermal decomposition of these films in an atmosphere of air was carried out in a thermo-gravimetric analyzer, and the films were also immersed into water to obtain water absorption. Results showed that the incorporation of MGL49 improved the thermal-oxidative aging resistance of natural rubber latex film when the MGL49 content was less than 50 phr, the water absorption increased with the increment of MGL49 content, and the NRL/MGL49 film containing 10phr of MGL 49 has a best thermal-oxidative stability and highest water absorption also.