Polymer blends aging studies

Table 14.13. Physical aging in polymer blends, studied by Stress relaxation, Mijovic equation parameters ...

As noted for rubbers, micro tests using scaled-down indentor sizes and smaller loads are being used, and special mention should be made of the micro Vickers test [18]. which has been applied successfully to plastics (sec Ref. [19] for a review) in the determination of crystallization effects, anisotropy, the effect of weathering and heat aging, the study of polymer blends, etc. 

In 1983 he joined the editorial board of Polymer, of which he thrar became main editor, and is also on the editorial boards of Journal of Applied Polymer Science, Polymer Contents, Polymers for Advanced Technologies, Korean Polymer Journal, and Trends in Polymer Science. He was awarded a D.Sc. from the Urriversity of Edinbtrrgh for Research Work on the hydrodynamics of polymCT solutiorrs, studies of relaxation processes in the glassy state of polymers, and on physical characterization of polymers. His crrrrent interests are centered on phase eqtrihbria in polymer blends, polymer hqtrid crystals, ion conduction in polymCT electrolytes, physical aging, and hqtrid crystalhne celltrlose/polymer blends and composites. 

The major difficulties involved in making electrically conductive thermoplastic blends using polyaniline, polypyrrole, or their composites, are two-fold. The first is the thermal instability of doped polyaniline and polypyrrole at melt processing temperatures (1-3), The second is the chemical incompatibility of acidic conductive polyaniline with acid sensitive polymers such as the nylons. Conductive polyaniline is quite acidic and the adjustment of its acidity to neutral pH values eliminates its high conductivity (4,5). The authors present here thermal aging studies of conductivity and thermal gravimetric analysis - mass spectroscopy (TGA-MS) of Eeonomers which show pH independence of conductivity in acidic to neutral environments. The tunable surface properties of Eeonomer composites allows one to optimize the processibility as well as the electrical and mechanical properties of their blends with various thermoplastics. 

Arrieta, C., David, E., Dolez, P., Vu-Khanh, T. Hydrolytic and photochemical aging studies of a Kevlar -PBI blend. Polym. Degrad. Stab. 96. 1411-1419 (2011)... 

Physical aging studies have been performed on several polymer-polymer mixtures Tables 6.1 and 6.2 list the systems investigated. Most of these studies have made use of DSC and enthalpic data to assess physical aging behavior in blends. 

While various spectroscopic techniques have heen used to investigate physical aging in amorphous polymers, very few studies have been reported on blends. As shown by studies on polymer-siUca nanocomposites [89-91], fluorescence and... 

Cowie, J.M.G. and Ferguson. R. (1989) Physical ageing studies in polymer blends. 2. Enthalpy relaxation as a function of ageing temperature in a poly (vinyl methyl ether)/polystyrene blend. Macromolecules, 22, 2312. 

The materials analyzed were blends of polystyrene (PS) and poly(vinyl methyl ether) (PVME) in various ratios. The two components are miscible in all proportions at ambient temperature. The photooxidation mechanisms of the homo-polymers PS and PVME have been studied previously [4,7,8]. PVME has been shown to be much more sensitive to oxidation than PS and the rate of photooxidation of PVME was found to be approximately 10 times higher than that of PS. The photoproducts formed were identified by spectroscopy combined with chemical and physical treatments. The rate of oxidation of each component in the blend has been compared with the oxidation rate of the homopolymers studied separately. Because photooxidative aging induces modifications of the surface aspect of the material, the spectroscopic analysis of the photochemical behavior of the blend has been completed by an analysis of the surface of the samples by atomic force microscopy (AFM). A tentative correlation between the evolution of the roughness measured by AFM and the chemical changes occurring in the PVME-PS samples throughout irradiation is presented. 

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