Journal ArticleDOI
Morphology-property studies of amorphous polycarbonate
K. Neki,P. H. Geil +1 more
TLDR
In this paper, the relationship between morphology and physical properties of amorphous poly-bisphenol-A carbonate was examined as a function of annealingtime at temperatures below the glass transition temperature (Tg).Abstract:
The relationship between morphology and several physical properties (tensile, thermal, dielectric, and dynamic mechanical properties) of amorphous poly-bisphenol-A-carbonate was examined as a function of annealingtime at temperatures below the glass transition temperature (Tg). The change in structure of the amorphous films was studied by means of X-ray diffraction and with electron diffraction using a rotating sector in an electron microscope as well as by electron micrographs of replicas of surfaces prepared by etching with dilute aqueous NaOH solutions. The changes in morphology and physical properties caused by annealing below Tg are, in general, closely related. The relationship cannot be explained only by changes in free volume; it is proposed that changes in the degree and type of order (nodular structure) also play a role. The design and application of the rotating sector is described in an Appendix.read more
Citations
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Glass Transition
TL;DR: Computer simulations of melting, crystallization, glass transition, and annealing for a model system of 864 Lennard-Jones atoms under a periodic boundary condition are carried out using constant-pressure molec ular dynamics techniques with temperature control to characterize the glass's stability.
Journal ArticleDOI
An overview of the nonequilibrium behavior of polymer glasses
Martin R. Tant,Garth L. Wilkes +1 more
TL;DR: In this article, the basic principles of nonequilibrium behavior are outlined, with emphasis placed on changes in material properties with annealing below the glass transition temperature, and free volume theory and thermodynamic theory are discussed.
Journal ArticleDOI
Refractive-index variations with temperature of PMMA and polycarbonate.
TL;DR: A relevant discontinuity of the coefficient of thermal expan sion has been observed for PMMAs various tacticities and a so-called α peak was observed at ~60°C and was widely discussed by Neki and Geil.
Journal ArticleDOI
The Durability of Epoxies.
Roger J. Morgan,James E. O'neal +1 more
TL;DR: In this paper, the state of knowledge of the basic factors that control the durability of epoxies in service environments is reviewed, and the effect of fabrication and environmental factors and their complex interactions on the formation of permanent damage regions are discussed.
Journal ArticleDOI
Mechanical properties, molecular motions and density fluctuations in polymer-additive mixtures
TL;DR: In this article, the β-suppression effect was studied on a number of polymers and additives (dynamic mechanical and dielectric measurements), the molecular motions involved are characterized (2H-NMR spectroscopy) and the thermal density fluctuations are measured (SAXS experiments).
References
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Journal ArticleDOI
X‐Ray Diffraction Methods
TL;DR: In this paper, the identification of crystalline materials, preferred orientations, particle sizes, strains, and structure randomness, x-ray diffraction is used to learn more about the identification.
Journal ArticleDOI
Molecular motions in polyethylene terephthalate
K.H. Illers,H. Breuer +1 more
TL;DR: In this paper, the molecular motions in polyethylene terephthalate samples of different crystallinities have been investigated by dynamic mechanical measurements at a frequency of 1 cycle/sec. between −180° and +260°C.
Journal ArticleDOI
Crystallization of polyethylene terephthalate from the glassy amorphous state
G. S. Y. Yeh,P. H. Geil +1 more
TL;DR: The morphology of glassy amorphous PETP is characterized by ball-like structures in which a paracrystalline-type order is present as mentioned in this paper, and movement of the balls is seen at annealing temperatures 5†C or more below Tg as well as at higher temperatures.
Journal ArticleDOI
Theory and Measurements of the Glass‐Transformation Interval of Polystyrene
TL;DR: In this paper, the hole theory of liquids was used as a basis for the analysis of the glass transition and the maximum of the apparent heat capacities found experimentally agrees with the theory.