Reprocessability of PHB in extrusion: ATR-FTIR, tensile tests and thermal studies

Mechanical recycling of biodegradable plastics has to be encouraged, since the consumption of energy and raw materials can be reduced towards a sustainable development in plastics materials. In this study, the evolution of thermal and mechanical properties, as well as structural changes of poly(hydroxybutyrate) (PHB) up to three extrusion cycles were investigated. Results indicated a significant reduction in mechanical properties already at the second extrusion cycle, with a reduction above 50% in the third cycle. An increase in the crystallinity index was observed due to chemicrystallization process during degradation by chain scission. On the other hand, significant changes in the chemical structure or in thermal stability of PHB cannot be detected by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA), respectively.National Foundation for Science and Technology Development (CNPq)Univ Fed Rio Grande Norte UFRN, Dept Mat Engn DEMat, Natal, RN, BrazilUniv Fed Sao Carlos UFSCar, Dept Mat Engn DEMa, Sao Carlos, SP, BrazilUniv Fed Paraiba UFPB, Dept Mat Engn DEMAT, Joao Pessoa, Paraiba, BrazilUniv Fed Rio Grande Norte UFRN, Dept Chem DQ, Natal, RN, BrazilUniv Fed Sao Paulo UNIFESP, Inst Sci & Technol ICT, Sao Jose Dos Campos, SP, BrazilUniv Fed Sao Paulo UNIFESP, Inst Sci & Technol ICT, Sao Jose Dos Campos, SP, BrazilWeb of Scienc