Effect of expandable thermoplastic microspheres on microcellular injection molded polylactic acid (PLA): Microstructure, surface roughness, and tensile properties

Jun Peng, Jian Wang, Ke Li, Lih Sheng Turng*, Xiang Fang Peng

*Corresponding author for this work

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

2 Scopus citations

Abstract

Microcellular injection molding is capable of producing light weight, dimensionally stable plastic parts while using less material and energy. Expandable thermoplastic microspheres (ETM) were employed as chemical blowing agents to produce biodegradable polylactic acid (PLA) parts. The surface characteristics of the samples were evaluated with a 2D surface roughness analyzer and a white-light 3D surface profiler (weight-light interferometer). It was found that microcellular injection molded parts with ETM exhibit good surface quality, similar to conventional solid injection molded parts. The tensile properties of injection molded PLA samples with variable ETM weight ratios have been investigated. The microstructure and cell density of the fractured cross-sectional surfaces were characterized by using a scanning electron microscope (SEM) and an image analysis tool. As shown by the testing results, the cell microstructures - such as cell size, cell density, and a layered structure with a foamed core sandwiched by solid skin layers - play an important role in the surface quality and mechanical properties. A smaller cell diameter and a thicker skin layer help to improve the surface smoothness and tensile properties of the microcellular injection molded parts with ETM. In addition, an appropriate microsphere content has a positive effect on cell microstructure and weight reduction, whereas too high a concentration of microspheres adversely affects the tensile properties and surface roughness.

Original languageEnglish
Title of host publication69th Annual Technical Conference of the Society of Plastics Engineers 2011, ANTEC 2011
Pages2643-2648
Number of pages6
StatePublished - 2011
Externally publishedYes
Event69th Annual Technical Conference of the Society of Plastics Engineers 2011, ANTEC 2011 - Boston, MA, United States
Duration: 01 05 201105 05 2011

Publication series

NameAnnual Technical Conference - ANTEC, Conference Proceedings
Volume3

Conference

Conference69th Annual Technical Conference of the Society of Plastics Engineers 2011, ANTEC 2011
Country/TerritoryUnited States
CityBoston, MA
Period01/05/1105/05/11

Keywords

  • Expandable thermoplastic microspheres
  • Microcellular injection molding
  • Surface roughness
  • Tensile properties

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