Effect of poly(tetrafluoroethylene) nanofibers on foaming behavior of linear and branched polypropylenes. (March 2017)

• Record Type: Journal Article
• Authors: Jurczuk, Kinga; Galeski, Andrzej; Morawiec, Jerzy
• Is Part Of: European polymer journal. Volume 88(2017)
• Page Start: 171
• Page End: 182
• Publication Date: 2017-03
• Subjects: Nanocomposites -- Poly(tetrafluoroethylene) nanofibers -- Strain hardening -- Foaming -- Cellular structure; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; Polymerization; Polymers; Periodicals; Electronic journals; 547.705
• DOI: 10.1016/j.eurpolymj.2017.01.024
• Languages: English
• ISSNs: 0014-3057

Abstract

Graphical abstract: Foams of neat LCB-PP and LCB-PP with PTFE nanofibers produced by autoclave-based bead foaming. Highlights: PTFE nanofibers improve the foamability of linear and branched PP resins. Faster stabilization of PP/PTFE foams resulting from higher Tc of the nanocomposites. PTFE nanofibers induced the strain hardening in linear PP resin. PP/PTFE foams exhibit few times smaller cells and higher cell concentration. Abstract: The influence of poly(tetrafluoroethylene) (PTFE) nanofibers, generated in situ during shear extrusion, on foaming behavior of linear (L-PP) and long-chain branched (LCB-PP) polypropylenes has been investigated. PTFE nanofibers significantly improved both thermal and rheological properties of PPs studied. PTFE nanofibers formed an entangled network and induced the strain hardening of PP/PTFE nanocomposites. Foams of neat PP and PP/PTFE nanocomposites were produced using continuous extrusion foaming and autoclave-based bead foaming. The presence of PTFE nanofibers resulted in much smaller foam cells and higher cell concentration as compared to neat PPs. In addition, the autoclave-based bead foaming showed that PTFE nanofibers nucleated cells formation in LCB-PP and participated in controlling the cells growth. The entanglements between PTFE nanofibers prevented excessive expansion of cells. As the result, expanded beads of LCB-PP/PTFE nanocomposite possessed ten times smaller cells, narrower cell size distribution and much higher cell concentration as compared to neat LCB-PP.