To clarify the relationship between rheological properties and foam processability for uncrosslinked polypropylene containing a newly developed processing modifier.
Polypropylene (PP) foams are strongly required in industry for various applications such as automobile parts, food tray and packaging, insulators, and shock-absorber, because of its heat resistant property and stiffness. However, it is significantly difficult to obtain foams with high expansion ratio, especially from uncrosslinked PP, because of the lack of the elastic nature in a molten state. In this project, a newly developed processing modifier, acrylic-modified polytetrafluoroethylene (PTFE), will be employed to enhance the strain-hardening in elongational viscosity of PP. The PTFE deforms into fibrous structure during mixing in a molten PP, and the entanglement of the obtained PTFE fibers is responsible for the marked strain-hardening. As a result, PP containing a small amount (0.5-5 wt%) of the modifier exhibits prominent melt tension with a small increase in shear viscosity. Further, the effect of the addition of the modifier will be studied also for thermoplastic olefinic elastomer obtained by dynamic vulcanization process. Furthermore, foaming processability will be evaluated by various processing operations as follows;
Chemical blowing agent
Microfoaming by supercritical CO2; batch-foaming and continuous extrusion foaming.
August 2011 – a IUPAC Technical Report entitled ‘Morphology development of polytetrafluoroethylene in a polypropylene melt’ has been published in Pure Appl. Chem., 2011, Vol. 83, No. 10, pp. 1819-1830, doi:10.1351/PAC-REP-11-01-10, online 2011-07-14
August 2013 – another report entitled ‘Effect of Flexible Fibers on Rheological Properties of Poly(Lactic Acid) Composites under Elongational Flow’ has been published in J. Soc. Rheol. (Jpn), 2013, Vol. 41, No. 3 p. 129-135, doi:10.1678/rheology.41.129, online 2013-07-25
project completed – page last updated 20140714