engleski

Improvement of the polymer properties by radiation grafting and crosslinking

Radiation grafting and crosslinking were applied in collaboration with local industry to demonstrate the possibility to improve the polymer properties. With the aim to prevent the losses of stabilizer due extractability or volatility during service time the photoprotector 2-hydroxy-4-(3-methacryloxy-2-hydroxy-propoxy) benzophenone has been grafted to low density polyethylene in benzene, tetrahydrofuran and methanol solution, respectively. Direct gamma irradiation method was used. Surface grafting occurs in methanol solution, grafting yield of stabilizer being less than 0.5%. In benzene and tetrahydrofuran grafting proceeds more or less in the inner parts of polymeric film, and the grafting yields are much higher. To test the improvement of photostability by grafting of protector polymer samples with grafted and nongrafted protector were exposed to artificial accelerated aging and to natural weathering, which means exposure to long-term direct action of the sun light and all climatic factors. Photooxidative changes were determined by IR spectroscopy and photodegradation by measurements of the physical properties. Measurements of the change of carbonyl index, elongation at break and tensile strength in the course of artificial and natural aging of LDPE, with grafted and nongrafted protector, have proven much higher photoprotection achieved by the grafted protector. The surface grafting is the most efficient and the most economical. It was shown that with the addition of 20 phr of polybutadiene waste rubber, grafted with ethylacrylate by direct gamma irradiation method, to polyacrylic rubber compound the properties of rubber worsend but remained within the range of properties characteristic for these types of rubber. The stability of rubber against swelling in hot mineral oil was satisfactory even when 30 phr of grafted waste rubber was added to polyacrylic rubber. Radiation crosslinked PVC pipes were produced. Circumferential stress determined from the pressure at repture at 80 °C, Shore hardness and Vicat softening temperature indicate much higher temperature resistance of radiation crosslinked pipes as compared with unirradiated pipes.

surface grafting of stabilizer ; photoprotection ; accelerated aging ; natural weathering ; grafting of waste rubber ; crosslinked PVC pipes

nije evidentirano