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Open AccessArticle

Mechanical Properties Distribution within Polypropylene Injection Molded Samples: Effect of Mold Temperature under Uneven Thermal Conditions

1
Department of Industrial Engineering, University of Salerno, via Giovanni Paolo II, 132, 84084 Fisciano, Italy
2
Institute for Polymers, Composites and Biomaterials (IPCB-CNR), Via Previati, 1/C, 23900 Lecco, Italy
*
Author to whom correspondence should be addressed.
Polymers 2017, 9(11), 585; https://doi.org/10.3390/polym9110585
Received: 13 October 2017 / Revised: 1 November 2017 / Accepted: 3 November 2017 / Published: 7 November 2017
(This article belongs to the Special Issue Processing-Structure-Properties Relationships in Polymers)
The quality of the polymer parts produced by injection molding is strongly affected by the processing conditions. Uncontrolled deviations from the proper process parameters could significantly affect both internal structure and final material properties. In this work, to mimic an uneven temperature field, a strong asymmetric heating is applied during the production of injection-molded polypropylene samples. The morphology of the samples is characterized by optical and atomic force microscopy (AFM), whereas the distribution of mechanical modulus at different scales is obtained by Indentation and HarmoniX AFM tests. Results clearly show that the temperature differences between the two mold surfaces significantly affect the morphology distributions of the molded parts. This is due to both the uneven temperature field evolutions and to the asymmetric flow field. The final mechanical property distributions are determined by competition between the local molecular stretch and the local structuring achieved during solidification. The cooling rate changes affect internal structures in terms of relaxation/reorganization levels and give rise to an asymmetric distribution of mechanical properties. View Full-Text
Keywords: indentation; Harmonix AFM; polymer morphology; mechanical properties indentation; Harmonix AFM; polymer morphology; mechanical properties
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MDPI and ACS Style

Liparoti, S.; Speranza, V.; Sorrentino, A.; Titomanlio, G. Mechanical Properties Distribution within Polypropylene Injection Molded Samples: Effect of Mold Temperature under Uneven Thermal Conditions. Polymers 2017, 9, 585.

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