TY - JOUR
T1 - Influence of molten-state annealing on the phase structure and crystallization behaviour of high impact polypropylene copolymer
AU - Chen, Ruifen
AU - Shangguan, Yonggang
AU - Zhang, Chunhui
AU - Chen, Feng
AU - Harkin-Jones, Eileen
AU - Zheng, Qiang
PY - 2011/6/8
Y1 - 2011/6/8
N2 - The phase structure evolution of high impact polypropylene copolymer (IPC) during molten-state annealing and its influence on crystallization behaviour were studied. An entirely different architecture of the IPC melt was observed after being annealed, and this architecture resulted in variations of the crystallization behaviour. In addition, it was found that the core-shell structure of the dispersed phase was completely destroyed and the sizes of the dispersed domains increased sharply after being annealed at 200 °C for 200 min. Through examination of the coarseness of the phase morphology using phase contrast microscopy (PCM), it was found that a co-continuous structure and an abnormal 'sea-island' structure generally appeared with an increase in annealing time. The original matrix PP component appeared as a dispersed phase, whereas the copolymer components formed a continuous 'sea-island' structure. This change is ascribed to the large tension induced by solidification at the phase interface and the great content difference between the components. When the temperature was reduced the structure reverted to its original form. With increasing annealing time, the spherulite profiles became more defined and the spherulite birefringence changed from vague to clear. Overall crystallization rates and nucleation densities decreased, but the spherulite radial growth rates remained almost constant, indicating that molten-state annealing mainly affects the nucleation ability of IPC, due to a coarsened microstructure and decreased interface area.
AB - The phase structure evolution of high impact polypropylene copolymer (IPC) during molten-state annealing and its influence on crystallization behaviour were studied. An entirely different architecture of the IPC melt was observed after being annealed, and this architecture resulted in variations of the crystallization behaviour. In addition, it was found that the core-shell structure of the dispersed phase was completely destroyed and the sizes of the dispersed domains increased sharply after being annealed at 200 °C for 200 min. Through examination of the coarseness of the phase morphology using phase contrast microscopy (PCM), it was found that a co-continuous structure and an abnormal 'sea-island' structure generally appeared with an increase in annealing time. The original matrix PP component appeared as a dispersed phase, whereas the copolymer components formed a continuous 'sea-island' structure. This change is ascribed to the large tension induced by solidification at the phase interface and the great content difference between the components. When the temperature was reduced the structure reverted to its original form. With increasing annealing time, the spherulite profiles became more defined and the spherulite birefringence changed from vague to clear. Overall crystallization rates and nucleation densities decreased, but the spherulite radial growth rates remained almost constant, indicating that molten-state annealing mainly affects the nucleation ability of IPC, due to a coarsened microstructure and decreased interface area.
KW - High impact polypropylene copolymer (IPC)
KW - Molten-state annealing
KW - Phase inversion
UR - http://www.scopus.com/inward/record.url?scp=79957819275&partnerID=8YFLogxK
U2 - 10.1016/j.polymer.2011.05.005
DO - 10.1016/j.polymer.2011.05.005
M3 - Article
AN - SCOPUS:79957819275
SN - 0032-3861
VL - 52
SP - 2956
EP - 2963
JO - Polymer
JF - Polymer
IS - 13
ER -