Polypropylene/Chemical Blowing Agent Foams: Effect of the Injection Speed and Core Back Distance on Microstructure and Mechanical Properties

Year 2020, Volume: 12 Issue: 2, 638 - 647, 30.06.2020

Meral Akkoyun , İbrahim Badem Mert Emre Öztoksoy Yeşim Aslan

https://doi.org/10.29137/umagd.711692

Abstract

In recent years, many parts of the automotive industry, previously made of metal, has been passed to polymers due to their light weight, ie lower carbon emission and fuel consumption advantage. The aim of this work was to investigate the microstructure and mechanical properties of chemical foaming agent added polypropylene foam samples produced by injection molding. In particular, the effects of injection speed and core back distance on the evolution of cell diameter, compact outer layer thickness, cell density and mechanical properties were examined. In the first step the effect of various injection speeds (110; 125; 140 mm/s) was investigated. Then, various core back positions (0; 0.7 and 1.5 mm) were analyzed at a constant injection speed (110 mm/s). The results showed an increase of the cell diameter, the compact outer layer thickness and the elastic modulus as the injection speed increases. In addition, an important effect of the core back distance was observed with the presence of a critical core back distance. Below this critical value, the cell diameter and the elastic modulus drop due to a notable decrease of the skin layer thickness. Above this critical value, the cells started to collapse and lose their circularity.

Keywords

Polypropylene Foam, Chemical Blowing, Injection Molding, Core back, Microstructure, Mechanical Properties

Supporting Institution

The Scientific Research Projects Units of Bursa Technical University

Project Number

172L09

Thanks

Tofaş Türk Otomobil Fabrikası A.Ş., Farplas Otomotiv A.Ş. and Karel Kalıp San. A.Ş. are gratefully acknowledged for the production of PP/CBA foams at different processing conditions. The Scientific Research Projects Units of Bursa Technical University (under the contract number of 172L09) are also gratefully acknowledged for their financial support.

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