Influence of Structural and Topological Constraints on the Crystallization and Melting Behavior of Polymers:  3. Bisphenol A Polycarbonate

Abstract

In this paper, we report differential scanning calorimetry studies of the temperature and molar mass dependences for the primary and secondary crystallization behavior of bisphenol A polycarbonate (BAPC). The molar mass dependence of the crystallization rate is found to be much stronger during primary than during secondary crystallization, confirming our earlier claims that primary and secondary processes occur by significantly different mechanisms. Investigations of the secondary crystallization process suggest the existence of a crossover phenomenon from secondary crystal formation at low temperatures to isothermal lamellar thickening at high temperatures. While the results of our low-temperature studies of BAPC provide further support for the model developed in a previous publication on poly(arylene ether ether ketone), evidences from atomic force microscopy and calorimetry of isothermal lamellar thickening above the crossover temperature lead us to anticipate a more unified view of polymer crystallization.

Solvent-free preparation, characterization, and properties of SEBS–g–polycarbonate copolymers

“…The crystallization temperature of PC may be independent of the molar mass however the crystallization kinetic depends strongly on the length of the chains and hence their mobility. [70] The crystallization is favorably observed for PC chains mixed with low molecular weight polymers. [71] In this study, SEC analyses prove that there are cleavages of the homopolymer PC chains, which increase the kinetic of crystallization.…”

Oriented Crystallization of Polycarbonate by Vapor Grown Carbon Fiber and its Application

“…The saturated value of the heat of fusion (26 J/g) was in good agreement with what was reported before. 6 It was confirmed in Figure 5 that the concentration could be reduced to 0.1 wt % with keeping the crystallization effect from VGCF Ò and diminishing that from the matrix.…”

“…annealing at 185 C. 6 WAXD suggested a distinguished peak appeared at 17.3 deg (the mixture of (020) (17.0 deg) and (202) (17.6 deg) diffraction of PC) when annealing around 200 C only for 2 h. 16 DSC and WAXD results allowed us to say that PC crystallization was enhanced in the presence of VGCF Ò . Dynamic melt rheological property as a function of time suggested the increase of storage and loss moduli around 200 C. It was reported that MWCNT also crystallizes a certain type of thermoplastic polyimide and polypropyrene.…”

“…[3][4][5] Recently, it was reported that the effect of molecular weight on the bulk crystallization of pure PC without any additives. 6 When PC (M w (weight-average molecular weight) = 28400) was annealed at 185 C, the heat of fusion gradually increased after the induction period of 50 h. 6 Carbon nanotubes (CNTs) have received considerable attention in terms of mechanical, electric, magnetic, and thermal properties. [7][8][9][10][11][12][13] For enhancing these properties in polymer matrixes, a series of investigations in PC/CNT composites have been performed, but were with no evidence of crystallization due to high investigated temperature (260 C).…”

Morphology and Rheological Behaviors of Polycarbonate/High Density Polyethylene in situ Microfibrillar Blends

“…PC could not crystallize under these conditions even though PC crystallization has been previously reported. [32,33] At 180 8C, PC is in a highly elastic state. where the relaxation time of physical entanglements between chains is considerably higher compared to the solidification time.…”