Pregledni rad
Improvement of the polymer properties by radiation grafting and crosslinking
Franjo RANOGAJEC
; Institut Ruđer Bošković, Zagreb
Marica MLINAC MIŠAK
; Institut Ruđer Bošković, Zagreb
Zvonimir HELL
; Institut Ruđer Bošković, Zagreb
Sažetak
Radiation grafting and crosslinking were applied in collaboration with local industry to demonstrate the possibility of improving the polymer properties. With the aim of preventing the losses of stabilizer due extractability or volatility during the service time the photo-protector 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 photo-stability by grafting of protector polymer samples with grafted and non-grafted protector were exposed to artificial accelerated aging and to natural weathering, which means exposure to long-term direct action of the sunlight and all climatic factors. Photo-oxidative changes were determined by IR spectroscopy and photo-degradation 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 non-grafted protector, have proven much higher photo-protection achieved by the grafted protector. The surface grafting is the most efficient and the most economical. It was shown that with the addition of 20phr of polybutadiene waste rubber, grafted with ethylacrylate by direct gamma irradiation method, to polyacrylic rubber compound the properties of rubber worsened 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 30phr of grafted waste rubber was added to polyacrylic rubber.
Radiation crosslinked PVC pipes were produced. Circumferential stress determined from the pressure at rapture at 80°C, Shore hardness and Vicat softening temperature indicate much higher temperature resistance of radiation crosslinked pipes as compared to unirradiated pipes.
Ključne riječi
accelerated aging; crosslinked PVC pipes; grafting of waste rubber; natural weathering; photo-protection; surface grafting of stabilizer
Hrčak ID:
36725
URI
Datum izdavanja:
29.4.2009.
Posjeta: 4.195 *