Thirawudh Pongprayoon

Ultrathin Film Formation by Gamma-Ray Induced Polymerization in Surfactant Template on Solid Surface

Ultrathin film of polyisoprene was formed on silica surface in the two dimensional adsorbed surfactant by gamma-ray induced polymerization. The effect of gamma irradiation total doses on polymeric film formation was investigated. The modified silica and formed film were characterized. The results showed the potential of the surface modification by polymer film-surfactant-silica hybrid.

Degree of Vulcanization of Rubber Latex by Capillary Viscometer

The degree of vulcanization of latex compound was determined by capillary viscometer with controlled temperature to study effect of time and temperature on vulcanization process. The standard equilibrium swelling test was also conducted to assess the degree of vulcanization. A latex compound for medical glove was investigated. The latex viscosity was observed to increase over time at above room temperature condition. On the other hand, the viscosity fluctuated around mean value at room temperature. This is partly consistent with the swell ratio measurement which complete vulcanization was observed at curing temperature of 60 °C.

Mechanical Properties of Poly(lactic acid) / Thermoplastic Starch Blends Crosslinked by Gamma Radiation

This research aims to determine the influences of radiation-induced crosslinking on the mechanical properties of polymer blends between poly (lactic acid) (PLA) and thermoplastic starch (TPS). PLA and TPS were mixed at different ratios (90:10, 80:20, 70:30, 60:40) in the presence of a crosslinking agent using a twin screw extruder. The blends were compression molded into films. The film samples were irradiated by gamma radiation at different doses. Gel fraction was used to determine crosslinking efficiency. Results showed that gamma radiation was able to induce crosslinking for PLA/TPS blends. The gel fraction and mechanical properties decreased with increasing TPS content. The optimum ratio of PLA:TPS with the maximum gel fraction and mechanical properties was 90:10 and the optimum dose was 40 kGy by gamma radiation.

Mechanical and Dynamic Properties of Silica-Filled Rubber Compounds

Natural rubber compound using different silicas, including unmodified silica, admicellar-modified silica and silica with silane coupling agent, were studied. The properties including cure characteristics, mechanical properties and dynamic properties were examined with the comparison of three compounds. The results show that cure characteristics of admicellar silica/rubber compound (Ad-Si/R) was shorter than those of unmodified silica/rubber compound (Un-Si/R) and silane coupling silica/rubber compound (Sil-Si/R). Mechanical properties of Ad-Si/R and Sil-Si/R were better than those of Un-Si/R. In addition, wet grip and rolling resistance analyzed from tan δ (5 Hz) at 0°C and 60°C, respectively, by DMA were found that the wet grip of Ad-Si/R was the best, whereas the rolling resistance of Sil-Si/R was the best, in the comparison.