Autor(es):
Barbosa, Carlos N. 
; Simões, Ricardo ; Franzen, Markus ; Viana, Júlio C.
Data: 2013
Identificador Persistente: http://hdl.handle.net/11110/299
Origem: CiencIPCA
Assunto(s): Thermomechanical environment characterisation
Descrição
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. Foundation for Science and Technology,
Lisbon, through the 3 Quadro Comunita´rio de Apoio, the POCTI and FEDER programs, and project PEst-C/CTM/LA0025/2011.
