Adhesion between thermoplastic elastomers and polyamide‐12 with different glass fiber fractions in two‐component injection molding

The usage of thermoplastic elastomers (TPEs) is increasing, and integrated hard‐soft parts can be mass produced by two‐component injection molding (or sequential molding). A key property of such parts, the adhesion between the two materials, is the topic of this study. The hard part (the first molded component) in this study was polyamide‐12 with 0 to 50 wt% glass fibers (PA12‐GF). As the second component, two TPEs were used: a vulcanized TPE and a styrenic TPE, both modified for adhesion to polyamides. The adhesion, assessed by 90° peel tests, increased with increasing melt temperatures and TPE injection rate, while it decreased with increasing glass fiber fraction in the PA12‐GF. Based on characterization of cross‐sections and fiber distributions near the interface, we propose some hypotheses for the effect of fiber fraction on the fusion between PA12‐GF and TPE. These hypotheses involve the near‐surface properties of the PA12‐GF materials, microstructure, thermo‐mechanical properties, and thermal properties. A direct effect of increasing the glass fiber fraction, that is, a reduction in adhesion as more fibers are present at the interface, does not seem to be a major effect, since few fibers are in direct contact with the TPE for any fiber fraction

Analysis of the Influence of Microcellular Injection Molding on the Environmental Impact of an Industrial Component

Microcellular injection molding is a process that offers numerous benefits due to the internal structure generated; thus, many applications are currently being developed in different fields, especially home appliances. In spite of the advantages, when changing the manufacturing process from conventional to microcellular injection molding, it is necessary to analyze its new mechanical properties and the environmental impact of the component. This paper presents a deep study of the environmental behavior of a manufactured component by both conventional and microcellular injection molding. Environmental impact will be evaluated performing a life cycle assessment. Functionality of the component will be also evaluated with samples obtained from manufactured components, to make sure that the mechanical requirements are fulfilled when using microcellular injection molding. For this purpose a special device has been developed to measure the flexural modulus. With a 16% weight reduction, the variation of flexural properties in the microcellular injected components is only 6.8%. Although the energy consumption of the microcellular injection process slightly increases, there is an overall reduction of the environmental burden of 14.9% in ReCiPe and 15% in carbon footprint. Therefore, MuCell technology can be considered as a green manufacturing technology for components working mainly under flexural load