Interfacial adhesion mechanisms in incompatible semicrystalline polymer systems

Chieh-Tsung Lo, Francis C. Laabs, Balaji Narasimhan

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20 Citations (Scopus)

Abstract

The mechanism of adhesion at semicrystalline polymer interfaces between isotactic polypropylene (iPP) and linear low-density polyethylene (PE) was studied with transmission electron microscopy (TEM) and an asymmetric-double- cantilever-beam test. From the TEM images, both the interfacial width and the lamellar thickness of the polymers were extracted. During annealing, the interfacial width increased with the annealing temperature, and this indicated the accumulation of amorphous polymers at the interface. The interfacial strength, determined from the critical fracture energy (G c), also increased with the annealing temperature and reached a maximum above the melting temperatures of iPP and PE, whereas the smallest G c value was obtained below the melting temperatures of the two materials. A mechanism of interfacial strengthening was proposed accounting for the competition between the inter diffusion of PE and crystallization of iPP. As the annealing temperature increased, the rates of PE diffusion and iPP crystallization increased. Although the crystallization of iPP hindered the interdiffusion of PE, both the interfacial width and the fracture energy increased with the temperature, and this indicated that PE interdiffusion dominated iPP crystallization. Below the critical temperature, the fracture surfaces of both iPP and PE were smooth, and chain pullout dominated the fracture mechanism. Above the critical temperature, iPP crystallization still hindered the interdiffusion, and crazes could be seen on the iPP side. Above the melting temperatures of the two materials, ruptured surfaces could also be seen on the PE side, and crazing was the fracture mechanism.

Original languageEnglish
Pages (from-to)2667-2679
Number of pages13
JournalJournal of Polymer Science, Part B: Polymer Physics
Volume42
Issue number14
DOIs
Publication statusPublished - 2004 Jul 15

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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