Let us congratulate on Dr. Lee. Her paper entitled Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) Microcellular Foams using a Melt Memory Effect as Bubble Nucleation Sites was accepted by ournal of Applied Polymer Science(IF:3.02）.
Jisuk Lee, Kenta Moriyama, Yuta Hikima, Masahiro Ohshima
Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) foams were prepared by a foam injection molding (FIM) process using nitrogen (N2) as a physical blowing agent. PHBH is a marine degradable polymer known for its heat treatment weakness. Gel permeation chromatography and rheological measurements showed that the molecular weight was reduced when the polymer was processed at a temperature higher than 160 ; however, it had a prominent melt memory of crystallization at a temperature lower than 170 . The melt memory effect increased the crystallization temperature and provided the crystal nucleation site, which became bubble nucleation sites in the foaming process. Microcellular foams, whose cell size is smaller than 30 mm and cell density higher than 3×108 cell/cm3, were prepared using the melt memory effect while suppressing the thermal decomposition by tuning the injected polymer’s temperature (melting temperature) and the core-back timing. The mechanical properties of the resulting foams were also evaluated to find that the high ductility PHBH microcellular foam was obtained at 150 melting temperature.