REACTIVE PROCESSING OF POLYETHYLENE AND P OLY(ETHYLENE-CO-VINYL ACETATE)

The progress of crosslinking reactions in the system low-density polye thylene/ethylenevinylacetate initiated by peroxide (1 wt.-% dicuinylpe roxid) was investigated. The reaction was carried out in a quasi-close d mixing chamber and the yield observed by measuring the temperature-c orrected-torque. The temperature and the evolutions per minute were ch anged step by step for the investigation of the influence of the proce ssing conditions on the crosslinking kinetics. Both the increase of te mperature and of rotor speed accelerated the radical reaction. The res ult of crosslinking of the pure components and of the LDPE/EVA compoun d was a decrease of cristallinity. Therefore, the dynamic E-modul fall s though a crosslinking reaction took place. The results were strongly influenced by the existing melt-morphology in the state before the ra dicals attacked the polymers. The melt morphology in the previous stat e determines also the yield, the resulting morphology and the mechanic al properties.