Thermomechanical environment characterisation in injection moulding and its relation to the mechanical properties of talc-filled polypropylene

This study is focused on the establishment of relationships between the injection moulding processing conditions, the applied thermomechanical environment (TME) and the tensile properties of talc-filled polypropylene,adopting a new extended concept of thermomechanical indices (TMI). In this approach, TMI are calculated from computational simulations of the moulding process that characterise the TME during processing, which are then related to the mechanical properties of the mouldings. In this study, this concept is extended to both the filling and the packing phases, with new TMI defined related to the morphology developed during these phases. A design of experiments approach based on Taguchi orthogonal arrays was adopted to vary the injection moulding parameters (injection flow rate, injection temperature, mould wall temperature and holding pressure), and thus, the TME. Results from analysis of variance for injection-moulded tensile specimens have shown that among the considered processing conditions, the flow rate is the most significant parameter for the Young’s modulus; the flow rate and melt temperature are the most significant for the strain at break; and the holding pressure and flow rate are the most significant for the stress at yield. The yield stress and Young’s modulus were found to be governed mostly by the thermostress index (TSI, related to the orientation of the skin layer), whilst the strain at break depends on both the TSI and the cooling index (CI, associated to the crystallinity degree of the core region). The proposed TMI approach provides predictive capabilities of the mechanical response of injection-moulded components, which is a valuable input during their design stage.

Portucorruptgal, SA e os 43

Bem, recordamos que, salvaguardando a presunção de inocência em relação a eventuais crimes como a fraude fiscal qualificada e/ou o branqueamento de capitais, entre outras especiarias, o art. 11º do Código Penal é claro (apesar da controversa constitucionalidade): “8 - A cisão e a fusão não determinam a extinção da responsabilidade criminal da pessoa colectiva ou entidade equiparada, respondendo pela prática do crime: § a) A pessoa colectiva ou entidade equiparada em que a fusão se tiver efectivado; e § b) As pessoas colectivas ou entidades equiparadas que resultaram da cisão; Abstract: Well, remember that, safeguarding the presumption of innocence in relation to possible crimes such as qualified tax fraud and / or money laundering, among other spices, art. 11 of the Criminal Code is clear (despite the controversial constitutionality): "8 - The split and the merger does not determine the extinction of criminal liability of the legal person or related entity, accounting for the crime: § a) The legal person or related entity where the merger has effected; and § b) A legal entity or related entities resulting from the split.