Morphology, barrier, and mechanical properties of biaxially deformed poly(ethylene terephthalate)-mica nanocomposites

• Published in: Polymer engineering and science 2012-03, Vol.52 (3), p.532-548
• Main Authors: Soon, Kok, Harkin-Jones, Eileen, Rajeev, Rajvihar S., Menary, Gary, Martin, Peter J., Armstrong, Cecil G.
• Format: Article
• Language: English
• Subjects: Applied sciences; Composites; Composition; Deformation; Deformations (Mechanics); Exact sciences and technology; Forms of application and semi-finished materials; Glass; Mechanical properties; Mica; Nanocomposites; Phase transitions; Polyethylene terephthalate; Polymer industry, paints, wood; Polymeric composites; Technology of polymers; Temperature effects; Transmission electron microscopy
• ISSN: 0032-3888; 1548-2634
• DOI: 10.1002/pen.22114

Nanocomposites of poly(ethylene terephthalate) PET with a partially synthetic fluoromica were prepared by melt mixing and extruded into sheet and subjected to large‐scale biaxial stretching. Transmission electron microscopy (TEM) analysis of the mica tactoids showed that biaxial stretching had caused the tactoids to be more orientated and with improved exfoliation. The moduli of the nanocomposites were enhanced with increasing mica loading and the reinforcement effect was higher when the stretch ratio was 2 or 2.5, accommodated by having more aligned tactoids and reduced agglomeration. Enhancement in modulus was less pronounced for a stretch ratio of 3. Storage modulus was enhanced more significantly above the glass transition temperature. The barrier properties were enhanced by addition of mica before and after stretching. The Halpin‐Tsai theory underpredicted the relative modulus of the PET nanocomposites, whereas the Nielsen model over‐predicted the relative permeability. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers