pps proceeding - Abstract Preview
pps proceeding
Symposium: S10 - Injection Molding
Poster Presentation
 
 

Effect of reprocessing cycles on the degradation of polypropylene copolymer filled with talc or montmorillonite during injection molding process.

Demori Renan (1)*, Weschenfelder Vandro Felipe (2), Ashton Elisa (3), Cāndido Luis Henrique Alves (3), Kindlein Wilson (3), Mauler Raquel Santos (1)

(1) Federal University of Rio Grande do Sul - Porto Alegre - Rio Grande do Sul - Brazil, (2) ULBRA - Canoas- RS - Brazil, (3) Federal University of Rio Grande do Sul - LDSM - Porto Alegre - Rio Grande do Sul - Brazil

Mechanical recycling of polymeric materials is a favorable technique resulting in economic and environmental benefits, especially in the case of polymers with a high production volume as the polypropylene copolymer (PP). However, recycling by reprocessing techniques can lead to thermal, mechanical or thermo-oxidative degradation that can affect the structure of the polymer and subsequently the material properties. PP filled with montmorillonite (MMT) or talc are widely produced and studied, however, its degradation reactions by reprocessing cycles are poorly studied so far. In this study, the effects of reprocessing cycles in the structure and in the properties of the PP/MMT and PP/Talc were evaluated. The samples were mixed with 5% talc or MMT Cloisite C15A in a twin-screw extrusion. After extrusion, this filled material was submitted to five reprocessing cycles through an injection molding process. In order to evaluate the changes induced by reprocessing techniques, the samples were characterized by DSC, FT-IR, Izod impact and tensile strength tests. The study showed that Young modulus, elongation at brake and Izod impact were not affected by reprocessing cycles, except when using talc. In this case, the elongation at brake reduced until the fourth cycle, showing rigidity increase. The DSC results showed that melting and crystallization temperature were not affected. It was observed a reduction of the crystalline index (Xc) of PP C15A according to the progress of the reprocessing cycles from 74% in the first cycle to 60% in following cycles. The use of talc did not change the values of Xc. A comparison of FT-IR spectra of the reprocessed indicated that in both samples, between the first and the fifth cycle, no noticeable change has occurred. Thus, there is no evidence of thermo oxidative degradation. In general, these results suggest that PP reprocessing cycles using MMT or Talc does not change the material properties until the fifth cycle.