The Origin of Annealing Peaks in Semicrystalline Polymers: Enthalpy Recovery or Melting?

2020 ◽  
Vol 53 (20) ◽  
pp. 8751-8756
Author(s):  
Christoph Schick ◽  
René Androsch
Keyword(s):  
Semicrystalline Polymers ◽  
Enthalpy Recovery

Study of Transcrystallization in Polymer Composites

1989 ◽  
Vol 170 ◽  
Author(s):  
Benjamin S. Hsiao ◽  
J. H. Eric
Keyword(s):  
Thermal Conductivity ◽  
Free Energy ◽  
Carbon Fiber ◽  
Plasma Treatment ◽  
Polymer Composites ◽  
High Performance ◽  
Interfacial Strength ◽  
Fiber Surface ◽  
Semicrystalline Polymers ◽  
First Case

AbstractTranscrystallization of semicrystalline polymers, such as PEEK, PEKK and PPS, in high performance composites has been investigated. It is found that PPDT aramid fiber and pitch-based carbon fiber induce a transcrystalline interphase in all three polymers, whereas in PAN-based carbon fiber and glass fiber systems, transcrystallization occurs only under specific circumstances. Epitaxy is used to explain the surface-induced transcrystalline interphase in the first case. In the latter case, transcrystallization is probably not due to epitaxy, but may be attributed to the thermal conductivity mismatch. Plasma treatment on the fiber surface showed a negligible effect on inducing transcrystallization, implying that surface-free energy was not important. A microdebonding test was adopted to evaluate the interfacial strength between the fiber and matrix. Our preliminary results did not reveal any effect on the fiber/matrix interfacial strength of transcrystallinity.

A Positron Annihilation Lifetime Study of Poly(Bisphenol-a Carbonate)

1986 ◽  
Vol 82 ◽  
Author(s):  
P. L. Jones ◽  
A. J. Hill ◽  
G. W. Pearsall ◽  
J. H. Lind
Keyword(s):  
Bisphenol A ◽  
Positron Annihilation ◽  
Thermal History ◽  
Thermal Response ◽  
Semicrystalline Polymers ◽  
Glass Transitions ◽  
Thermal Dependence ◽  
Positron Annihilation Lifetime ◽  
Ductile To Brittle Transition ◽  
Increasing Temperature

ABSTRACTPositron annihilation lifetime spectroscopy has proven to be sensitive to glass transitions and other free volume dependent phase transitions in amorphous and semicrystalline polymers. The thermal dependence of the lifetime spectra of positrons in compression-molded poly(bisphenol-A carbonate) has been measured from 253K to 323K, then modelled using a three component fit. The longest-lived component lifetime τ3 was found to vary linearly with increasing temperature independent of thermal history. The corresponding component intensity I3 was found to vary in a non-linear fashion with increasing temperature, exhibiting a significant dependence on thermal history. The observed thermal response of τ3 and I3 is discussed in terms of both molecular relaxation and the ductile-to-brittle transition behavior of poly(bisphenol-A carbonate).

Effect of the crystallinity and morphology on the microcellular foam structure of semicrystalline polymers

1996 ◽  
Vol 36 (21) ◽  
pp. 2645-2662 ◽  
Author(s):  
Saeed Doroudiani ◽  
Chul B. Park ◽  
Mark T. Kortschot
Keyword(s):  
Semicrystalline Polymers ◽  
Microcellular Foam ◽  
Foam Structure
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