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J. Koszkul

A study on the degree of crystallinity of thermoplastics after injection molding and annealing

Polimery 1999, No 4, 255



DOI: dx.doi.org/10.14314/polimery.1999.255


Summary

The degree of crystallinity (Sk) was determined in two partially crystalline thermoplastics, Polyacetal (POM) (Tamoform 300) and polypropylene (PP) (Malen P, J-400) and in selected PP + filler systems. Injection molded test pieces, annealed or not, were examined by DTA, DSC and WAXS (Table 1). The Sk based on the entire mass of the system was found to be related to the nature of the filler used, especially when crystalline or amorphous. Neither DTA nor DSC affects the filler; therefore, the measurement gives the enthalpy of melting of the polymer itself. In WAXS, X-rays are diffracted or scattered also on filler molecules. For polymer + filler systems, neither DTA nor DSC is believed to be useful for determining the degree of crystallity. Annealing of injection molded specimens affected Sk essentially.
Keywords: polymer + filler systems, methods for determining the degree of crystallinity, annealing of injection-molded specimens, polyacetal, polypropylene

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