Polymer
Experimental observations of the effect of shear flow on the miscibility of binary polymer blends are compared to calculations based on a generalized Gibbs energy of mixing Gγ˙. This mixing free energy characterizes the steady state established at shear rateγ˙, as the sum of G z , the equilibrium Gibbs energy and E s , the energy the system stores while flowing.
Phenylphosphine oxide-containing polyimides, poly(arylene ether 1,3,4-oxadiazole)s and poly(arylene ether benzimidazole)s were prepared and evaluated for resistance to an oxygen plasma. Thin films of the phenylphosphine oxide-containing polymers were exposed to a radiofrequency-generated oxygen plasma under vacuum along with Kapton ® HN and polymers of similar chemical structure that did not...
Toluene self-diffusion coefficients in solutions of linear and crosslinked polystyrene (PS) at concentrations up to 30 wt% polymer have been determined over the temperature range 143–230 K using the 1 H n.m.r. static gradient stimulated echo method. At similar polymer concentrations, the diffusion coefficient values of toluene were higher for mixtures with crosslinked PS than for solutions...
The lower critical solution temperature (LCST) type phase behaviour of a poly(styrene-co-acrylonitrile)/ polycarbonate blend was verified by time-resolved light scattering analysis of the kinetics of both phase separation (above LCST) and phase dissolution (below LCST). The diffusion coefficient for separation was much larger than that of dissolution. The kinetic results provided a plausible scenario...
The synthesis and properties of 2,2′-dibromobisphenol A polycarbonate (2,2′-DBBA PC) were studied. The monomer, 2,2′-DBBA, was selectively prepared by the direct bromination of bisphenol A in dichloromethane with an inert gas purge. High molecular weight 2,2′-DBBA PC was prepared by interfacial phosgenation of the monomer followed by coupling of the resulting oligomers catalysed by 4-N,N-dimethylaminopyridine...
Hydrogel of poly(N-n-propylacrylamide) was prepared and its swelling dependence on temperature and pressure was investigated. Dramatic volume change of the gel with pressure and temperature was observed.
Thermoset/thermoplastic blends, namely triglycidyl p-aminophenol/poly(ether sulfone) (epoxy/PES) systems, were cured using a curing agent, 4,4′-diaminodiphenylsulfone, and the morphology in the cured resins was observed by electron microscopy. In contrast to the spherical domain structure in a non-reactive PES system, a bicontinuous two-phase structure was obtained when reactive PES with amine chain...
The fluorescence properties of bisphenol A polycarbonate (PC) solids were studied in detail as a function of casting and annealing temperatures (40–180°C), resulting in the establishment of a method to measure the pure fluorescence spectrum of PC solids. The spectrum was subject to contamination by a photoproduct of PC, which was assumed to have a similar structure to 2,2′-dihydroxydiphenyl. The existence...
Several compounds containing multiple phenylethynyl substituents were prepared and polymerized to thermosets through the acetylenic units. Pyrolysis of the polymers afforded high carbon yields. The acetylenic-based compounds were synthesized from the palladium-catalysed coupling reaction of phenyl-acetylene with multiple-brominated benzenes. Inconsistencies were observed in the reaction yields with...
Short- and long-term tensile creep tests of high-density polyethylene (HDPE) have been performed at different stress levels under an ambient temperature of 20°C. The effects of stress and physical ageing on the creep compliance are studied. The short-term creep data show that the distribution of relaxation times of HDPE is shifted even by a very low stress. Acceleration of creep can be realized by...
Polymerizations of ethylene or propylene were conducted in toluene employing the soluble catalytic system TiCl 4 . THF/AlCl 2 (C 2 H 5 )/Al(i-C 4 H 9 ) 3 combined with different metal chlorides (CoCl 2 ,MgCl 2 or ZnCl 2 ) complexed with tetrahydrofuran (THF). The catalyst activity was strongly dependent upon the metal...
The properties of ampholytic poly[N,N -dimethyl(acrylamido propyl) ammonium propane sulfonate] (poly(DMAAPS)) in aqueous solution were studied by measurements of cloud point determination and intrinsic viscosity. The minimum salt concentration and intrinsic viscosity of this polyampholyte were related to the type and concentration of added salt. Soft salt cations and anions bound more easily...
Methyl 2-(acyloxymethyl)acrylates [CH 2 C(CH 2 OCOR)COOCH 3 ; R = CH 3 , CH 2 CH 2 CH 3 , CH(CH 3 ) 2 and C(CH 3 ) 3 ] were prepared by nucleophilic substitution of methyl 2-(bromomethyl)acrylate with the desired carboxylic acid in the presence of triethylamine at ambient temperature. These particular monomers...
Wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (d.s.c.) measurements were made on cellulose tributyrate (CTB). In one case, CTB precipitated from solution in powdered form was annealed at different temperatures. In a second case, CTB was isothermally crystallized either from the melt or from the glass. Samples annealed from the powder showed higher crystallinity with respect...
Unsaturated homopolyamide was prepared from 3-aminocinnamic acid (ACA) by the phosphorylation polycondensation method. In addition, various copolyamides were prepared from ACA and 4-aminobenzoic acid. Furthermore, an unsaturated homopolyamide was synthesized from 4-carboxycinnamic acid and 4,4 -diaminodiphenylmethane. The physical, chemical and thermal properties of the polyamides were correlated...
1H n.m.r. relaxation data, determined via either wide-line 1 H n.m.r. or high-resolution solid-state 1 3 C n.m.r., were used to analyse the existence and extent of interphasic regions in dimethylsiloxane-styrene block copolymers. Results thus obtained have shown that copolymers having very short blocks possess relatively large interphases characterized by intermediate mobility...
The structural changes in the uniaxial drawing process of an unoriented amorphous film of poly(ethylene naphthalene-2,6-dicarboxylate) (PEN) and in the heating process of an oriented amorphous film of PEN were studied using X-ray diffraction apparatus equipped with imaging plates. This apparatus allows us to record a time-resolved series of two-dimensional patterns of wide-angle X-ray diffraction...
The conditions for processing and doping of blends of poly(o-alkoxyaniline)s and poly(vinylidene fluoride) were investigated. Flexible, free-standing and stretchable films of blends of various compositions were obtained by casting. A low percolation threshold was observed with the onset of conductivity at low polyalkoxyaniline contents (i.e. 5%). Interestingly, these blends displayed electrochromism...
The difference in heat capacity of the liquid state and that of the glassy state at the glass transition temperature, ΔC p (T g ) = C p ( 1 ) - C p ( g ) , has been determined in samples of epoxy resin with different extents of cure. The epoxy was a diglycidyl ether of bisphenol A cured isothermally by phthalic anhydride as hardener in a temperature...