Optimization of injection molding parameters for poly(styrene-isobutylene-styrene) block copolymer

Mauro Fittipaldi, Carla Garcia, Luis A. Rodriguez, Landon R. Grace

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations


Poly(styrene-isobutylene-styrene) (SIBS) is a widely used thermoplastic elastomer in bioimplantable devices due to its inherent stability in vivo. However, the properties of the material are highly dependent on the fabrication conditions, molecular weight, and styrene content. An optimization method for injection molding is herein proposed which can be applied to varying SIBS formulations in order to maximize ultimate tensile strength, which is critical to certain load-bearing implantable applications. The number of injection molded samples required to ascertain the optimum conditions for maximum ultimate tensile strength is limited in order to minimize experimental time and effort. Injection molding parameters including nozzle temperature (three levels: 218, 246, and 274 °C), mold temperature (three levels: 50, 85, and 120 °C), injection speed (three levels: slow, medium and fast) and holding pressure time (three levels: 2, 6, and 10 seconds) were varied to fabricate dumbbell specimens for tensile testing. A three-level L9 Taguchi method utilizing orthogonal arrays was used in order to rank the importance of the different injection molding parameters and to find an optimal parameter setting to maximize the ultimate tensile strength of the thermoplastic elastomer. Based on the Taguchi design results, a Response Surface Methodology (RSM) was applied in order to build a model to predict the tensile strength of the material at different injection parameters. Finally, the model was optimized to find the injection molding parameters providing maximum ultimate tensile strength. Subsequently, the theoretically-optimum injection molding parameters were used to fabricate additional dumbbell specimens. The experimentally-determined ultimate tensile strength of these samples was found to be in close agreement (1.2%) with the theoretical results, successfully demonstrating the suitability of the Taguchi Method and RSM for optimizing injection molding parameters of SIBS.

Original languageEnglish (US)
Title of host publicationProceedings of PPS 2015
Subtitle of host publicationThe 31st International Conference of the Polymer Processing Society - Conference Papers
EditorsByungohk Rhee
PublisherAmerican Institute of Physics Inc.
ISBN (Electronic)9780735413603
StatePublished - Mar 9 2016
Event31st International Conference of the Polymer Processing Society, PPS 2015 - Jeju Island, Korea, Republic of
Duration: Jun 7 2015Jun 11 2015

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


Other31st International Conference of the Polymer Processing Society, PPS 2015
Country/TerritoryKorea, Republic of
CityJeju Island


  • Injection Molding Optimization
  • Response Surface Methodology
  • SIBS
  • Taguchi Method

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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