Determination of the Avrami exponent of partially crystallized polymers by DSC- (DTA-) analyses

This paper presents a new method for a rapid determination of the Avrami exponentn by nonisothermal thermoanalytic analysis (DSC and DTA, resp.). Contrary to conventional techniques this method can be used in the entire temperature range and therefore it is applicable to polymers crystallizing from the melt. The proposed technique is applied to injection moulded low density polyethylene (LDPE), injection moulded high density polyethylene (HDPE), unpigmented extruded polypropylene (PP_unpigm.) and pigmented extruded polypropylene (PP_pigm.). The resulting values for the Avrami exponentsn _LDPE～2.9,n _HDPE～1.3, (n_{PP_{unpigm} }) ～2.2 and (n_{PP_{pigm} }) ～ 2.1 derived by crystallization from the melt were compared with isothermal measurements and with results given by other authors.