Reprocessability and melting behaviour of self-reinforced composites based on PP homo and copolymers

• Published in: Journal of thermal analysis and calorimetry 2010-07, Vol.101 (1), p.255-263
• Main Authors: Bárány, Tamás, Izer, András, Menyhárd, Alfréd
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Applied sciences; Chemistry; Chemistry and Materials Science; Composite materials industry; Composites; Exact sciences and technology; Forms of application and semi-finished materials; Injection molding; Inorganic Chemistry; Mathematical analysis; Matrices; Matrix methods; Measurement Science and Instrumentation; Melting; Physical Chemistry; Polymer industry, paints, wood; Polymer matrix composites; Polymer Sciences; Polypropylenes; Reprocessing; Technology of polymers
• ISSN: 1388-6150; 1588-2926
• DOI: 10.1007/s10973-010-0741-9

In our present study, the reprocessability of a self-reinforced PP composites (SRPPC) prepared by compression molding was studied. The composite materials (handled separately, based on the related matrix material) were ground, then extruded five times and injection molded after the first and fifth cycle in order to investigate the behaviour of the material during reprocessing. As a reference, the matrices of the composites were also reprocessed and injection molded similarly to the composites. On the manufactured specimens, static (tensile and flexural) and dynamic mechanical tests (Charpy) were performed. The melting and crystalline characteristics were studied by Differential Scanning Calorimetry (DSC). The probable decomposition caused by multiple extrusions was followed by the Melt Volume Rate (MVR). The results indicated that in case of commercial materials there is no significant degradation even after multiple reprocessing cycles; therefore, the reprocessability of SRPPC products has no hindrance. The presence of α-iPP reinforcement in the rPP-based composites after reprocessing results in increased inclination for crystallization and consequently leads to improved mechanical stiffness compared to rPP neat matrices.