Structural properties and mechanical behavior of injection molded composites of polypropylene and sisal fiber

X. L. Xie, R. K.Y. Li, S. C. Tjong, Y. W. Mai

Research output: Journal article publicationJournal articleAcademic researchpeer-review

48 Citations (Scopus)

Abstract

Composites based on isotactic polypropylene (PP) and sisal fiber (SF) were prepared by melt mixing and injection molding. The melt mixing characteristics, thermal properties, morphology, crystalline structure, and mechanical behavior of the PP/SF composites were systematically investigated. The results show that the PP/SF composites can be melt mixed and injection molded under similar conditions as the PP homo-polymer. For the composites with low sisal fiber content, the fibers act as sites for the nucleation of PP spherulites, and accelerate the crystallization rate and enhance the degree of crystallinity of PP. On the other hand, when the sisal fiber content is high, the fibers hinder the molecular chain motion of PP, and retard the crystallization. The inclusion of sisal fiber induces the formation of β-form PP crystals in the PP/SF composites and produces little change in the inter-planar spacing corresponding to the various diffraction peaks of PP. The apparent crystal size as indicated by the several diffraction peaks such as L(110)α, L(040)α, L(130)α and L(300)β of the α and β-form crystals tend to increase in the PP/SF composites considerably. These results lead to the increase in the melting temperature of PP. Moreover, the stiffness of the PP/SF composites is improved by the addition of sisal fibers, but their tensile strength decreases because of the poor interracial bonding. The PP/SF composites are toughened by the sisal fibers due to the formation of β-form PP crystals and the pull-out of sisal fibers from the PP matrix, both factors retard crack growth.

Original languageEnglish
Pages (from-to)319-328
Number of pages10
JournalPolymer Composites
Volume23
Issue number3
DOIs
Publication statusPublished - Jun 2002
Externally publishedYes

ASJC Scopus subject areas

  • Ceramics and Composites
  • General Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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