Crystallization and chemi-crystallization of recycled photo-degraded polypropylene
2004; Elsevier BV; Volume: 46; Issue: 2 Linguagem: Inglês
10.1016/j.polymer.2004.11.019
ISSN1873-2291
AutoresI.H. Craig, J. R. White, Phua Chai Kin,
Tópico(s)Polymer Nanocomposites and Properties
ResumoInjection moulded bars have been made from virgin polypropylene and from blends containing recycled photo-degraded polypropylene, then subjected to further ultraviolet (UV) exposure. Crystallinity measurements have been made at different depths from the exposed surface using X-ray diffraction and differential scanning calorimetry. Strong evidence for chemi-crystallization is provided for the photo-degraded samples. The crystallinity results are interpreted in terms of molecular scission and photo-initiated molecular defects. Scission leads to greater crystallizability and accounts for the observed chemi-crystallization. Molecular defects inhibit crystallization and eventually limit chemi-crystallization, as observed with a blend containing 75% virgin material and 25% recycled photo-degraded polymer after further UV exposure.
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