Stabilization of Polypropylene for Rotational Molding Applications

Authors

  • Iñaki Emaldi Institute of Polymeric Materials POLYMAT, University of the Basque Country UPV/EHU, Joxe Mari Korta Centre, Av. Tolosa 72, San Sebastian, 20018, Spain
  • Christopher Mark Liauw Division of Mechanical Engineering, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK
  • Herman Potgieter School of Chemical and Metallurgical Engineering, University of the Witwatersrand, P.O. Wits, 2050, South Africa

DOI:

https://doi.org/10.6000/1929-5995.2015.04.04.2

Keywords:

Polyolefins, Rotational Molding, Antioxidants, Thermal Oxidation.

Abstract

Rotational molding (RM) is a useful process for making large hollow objects. Due to its relatively high toughness and forgiving thermal oxidative degradation behavior, polyethylene is a most widely used material. However, it has too low elastic modulus for some important applications which leads to adaptation of polypropylene (PP) as a RM material. PP requires specially tailored antioxidant (AO) packages if it is to have any chance of surviving the often long (up to ca. 30 minutes) cycle times associated with RM. During the study the addition of the following stabilizers and antioxidants (AO) to the PP copolymer were investigated: a hindered phenolic primary AO, a phosphite secondary AO, a thioester secondary AO and a hindered amine light stabilizer. Synergistic effects between the primary and secondary AOs, as well as optimum heating times, were investigated. During the investigation formulations were prepared by compression molding and bench-scale RM. The combination resulting in the most effective synergism is the hindered phenolic primary antioxidant combined with the phosphite secondary antioxidant. A gel silica controlled release agent for the stabilizers was also investigated but did not yield significant improvements in stabilization.

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Published

2016-01-11

How to Cite

Emaldi, I., Liauw, C. M., & Potgieter, H. (2016). Stabilization of Polypropylene for Rotational Molding Applications. Journal of Research Updates in Polymer Science, 4(4), 179–187. https://doi.org/10.6000/1929-5995.2015.04.04.2

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