Isothermal crystallization behavior of isotactic polypropylene/polyhedral oligomeric silsesquioxane nanocomposites

Jean Hong Chen*, Hsin Lung Chen, Wei Tsung Chuang, U. Ser Jeng

*Corresponding author for this work

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

Abstract

The isothermal crystallization kinetics and morphology developments of iPP/POSS nanocomposites presented an unusual crystallization behaviors. The exothermic morphologies of isothermal crystallization of iPP/POSS composites changed remarkable with increasing POSS. Moreover, the morphology development of spherulitic for iPP/POSS composites showed the POSS molecules became nanocrystals firstly and then aggregated together forming thread- or network-like morphologies at very small loading of POSS. It implies that the POSS nanocrystals appeared an effective nucleating agent for iPP to promote the nucleation rate and to retarde the growth rate of iPP during crystallization. Therefore, the isothermal crystallization showed a single exothermic peak at lower POSS content, whereas, at larger POSS content, which displayed the multi-exothermic peaks during isothermal crystallization corresponded to the POSS molecules were both influenced the terms of transport the molten iPP chain and formation the critical nuclei of iPP. The crystallization mechanisms of multiexothermic peaks may proceed to combine the "nucleating agent inducing nucleation rate of iPP"and "network structure of POSS nanocrystals retarding growth rate of iPP"due to the network structure of POSS nanocrystals retarded the molted iPP chains diffusing and folding rate during crystallization. Therefore, in this work, we proved the multi-exothermic morphologies of iPP/POSS composites by Hoffman and Lauritzen theory. The majority POSS nanocrystals essentially acted an effectively nucleating agent role to reduce the energy required for formation of the critical size iPP nuclei, Kg, attributed to decrease in the fold surface free energy, ?e, of iPP during nucleation. Whereas, some minority POSS molecules, dispersed at the molecular level in the bulk region, presented an effectively inhibiting agent to retard the growth rate of iPP corresponded to increase in the activation energy of polymer segments, U*, from melted region transporting to the crystal surface as POSS content is increased.

Original languageEnglish
Title of host publication7th Asian-Australasian Conference on Composite Materials 2010, ACCM 2010
PublisherACCM-7 Organizing Committee
Pages1127-1130
Number of pages4
ISBN (Print)9781632660756
StatePublished - 2010
Externally publishedYes
Event7th Asian-Australasian Conference on Composite Materials 2010, ACCM 2010 - Taipei, Taiwan
Duration: 15 11 201018 11 2010

Publication series

Name7th Asian-Australasian Conference on Composite Materials 2010, ACCM 2010
Volume2

Conference

Conference7th Asian-Australasian Conference on Composite Materials 2010, ACCM 2010
Country/TerritoryTaiwan
CityTaipei
Period15/11/1018/11/10

Keywords

  • Ipp/poss composites
  • Isothermal crystallization kinetics
  • Nucleating agent inducing crystallization

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