Effect of nucleating agent and two-stage expansion on the morphology and mechanical properties of microcellular injection molded thermoplastic polyurethane

Thomas Ellingham, Hrishikesh Kharbas, Mihai Manitiu, Guenter Scholz, Lih Sheng Turng

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

Improved rebound resilience while lowering bulk density is desirable in several sport-wear applications. While rebound resilience properties generally deteriorate with reduction of the bulk density of the foam, a method of increasing rebound resilience by improving the control on microstructure is explored in this study. Low density thermoplastic polyurethane (TPU)/clay nanocomposite foamed parts were prepared using twin-screw extrusion compounding followed by microcellular injection molding. Samples with two densities were created by microcellular injection molding and an optional cavity expansion at a preset time during cooling. Scanning electron microscopy, rheological analysis, uniaxial compression tests, and rebound resilience tests were conducted on both of the non-expanded and expanded samples. Presence of well dispersed nanoclay in the TPU matrix acting as a nucleating and melt strengthening agent, coupled with cell growth at lower temperature helped achieve better microstructures, especially at high density reductions. The expansion of TPU at lower temperatures with directional second-stage expansion also helped to increase the rebound resilience, while achieving softer foams and lower hysteresis loss ratios at lower densities.

Original languageEnglish
Title of host publication75th Annual Technical Conference and Exhibition of the Society of Plastics Engineers, SPE ANTEC Anaheim 2017
PublisherSociety of Plastics Engineers
Pages1461-1467
Number of pages7
ISBN (Electronic)9780878493609
ISBN (Print)978-0-692-88309-9
StatePublished - 2017
Externally publishedYes
Event75th Annual Technical Conference and Exhibition of the Society of Plastics Engineers, SPE ANTEC Anaheim 2017 - Anaheim, United States
Duration: 08 05 201710 05 2017

Publication series

NameAnnual Technical Conference - ANTEC, Conference Proceedings
Volume2017-May

Conference

Conference75th Annual Technical Conference and Exhibition of the Society of Plastics Engineers, SPE ANTEC Anaheim 2017
Country/TerritoryUnited States
CityAnaheim
Period08/05/1710/05/17

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