Mechanical properties of a cryogenically mechanically alloyed polycarbonate–poly(aryl ether ether ketone) system

The processing–property relationship of a model cryogenically mechanically alloyed polymer–polymer system [polycarbonate (PC) and poly(aryl ether ether ketone) (PEEK)] was investigated. PC and PEEK powders were cryogenically mechanically alloyed for 10 h, and the resulting two‐phase powder particles were processed into testable coupons with a miniature ram‐injection molder. The bulk mechanical properties of the coupons made from the mechanically alloyed powders and nonmechanically alloyed powders were investigated as a function of mechanical alloying and injection‐molding parameters. The injection‐molded coupons were mechanically tested in the three‐point‐bending mode. The results demonstrated that no measurable improvement was achieved in the energy to break, strain at failure, or failure strength in the coupons made from the mechanically alloyed materials in comparison with those of the coupons made from the nonmechanically alloyed powders. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1196–1202, 2003     

Microporous anisotropic phase inversion membranes from bisphenol A polycarbonate: Effect of additives to the polymer solution

Phase inversion is a very flexible technique to obtain membranes with a large sort of morphologies. Membrane properties can vary greatly depending on the kind of polymer system used. Bisphenol A polycarbonate (PC) could be used as a phase inversion membrane base polymer, and presents very good properties. Nevertheless, very little information on membrane preparation using PC and the phase inversion process can be found in the literature. In this work flat‐sheet microporous membranes were obtained by the phase inversion process using the immersion precipitation technique. A new polymer system was studied, consisting of polycarbonate, N‐methyl‐2‐pyrrolidone as solvent, water as the nonsolvent, and an additive. The influence of some parameters on membrane morphology, such as polymer solution composition, exposition time before immersion into the precipitation bath, and the kind of additive was investigated. Precipitation was followed using light transmission experiments and membrane morphology was observed through Scanning Electron Microscopy (SEM). The viscosity and cloud points of all polymer solutions were also determined. The results were related to the studied synthesis parameters, using the basic principles of membrane formation by the phase inversion technique, looking forward to establishing criteria to control the morphology of flat‐sheet membranes using polycarbonate as the base polymer. The results showed that both additives were able to increase pore interconnectivity and even suppress macrovoid formation. The decrease in the miscibility region of the polymer system and increase in mass transfer resistance are found to be the determining factors during polymer solution precipitation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3085–3096, 2002     

Tensile modulus modeling of carbon‐filled nylon 6,6 and polycarbonate‐based resins

Electrically and thermally conductive resins can be produced by adding conductive fillers to insulating polymers. Mechanical properties, such as tensile modulus, are also important. This research focused on performing compounding runs followed by injection molding and tensile testing of carbon‐filled nylon 6,6 and polycarbonate‐based resins. The three carbon fillers investigated included an electrically conductive carbon black, synthetic graphite particles, and a milled pitch–based carbon fiber. For each polymer, resins were produced and tested that contained varying amounts of these single‐carbon fillers. In addition, combinations of fillers were investigated by conducting a full 2³ factorial design and a complete replicate in each polymer. These tensile modulus experimental results were then compared to results predicted by several different models. For the composites containing only one filler type, the Nielsen model with the modified Ψ term provided the best prediction of the actual experimental values. For the composites containing more than one filler type, a new parameter, which includes the vibrated bulk density (VBD) of the fillers, was incorporated into the Nielsen model with the modified Ψ term. This model with the new VBD parameter provided the best estimate of experimental tensile modulus for composites containing multiple‐filler types. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1716–1728, 2003     

Modeling the large‐strain constitutive behavior of polycarbonate under isothermal and anisothermal conditions

The tensile behavior of polycarbonate was studied at large strains below the glass‐transition temperature. Experiments were carried out at a series of constant temperatures and also under conditions of falling temperatures. The specimens necked with a natural draw ratio of approximately 2, and the study was mainly focused on the necked material. Isothermal experiments revealed an elastic mechanism that initiated beyond the natural draw ratio. A model consisting of an Eyring process and two Gaussian elastic mechanisms was found to be applicable to both the isothermal and anisothermal stress‐relaxation and stress–strain results. The same model also produced reasonable estimates of the stresses generated during the necking process. In addition, a simple relationship between the isothermal and anisothermal stress relaxation was demonstrated. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 2105–2116, 2005     

Compatibilization of polymer blends from poly(styrene‐co‐acrylonitrile) and polycarbonate by oxazoline modification of poly(styrene‐co‐acrylonitrile) in the melt

A good way of achieving compatibility in polymer blends of poly(styrene‐co‐acrylonitrile) (S/AN) and bisphenol A polycarbonate (PC) is the chemical modification of S/AN in the melt. A catalyzed reaction of the nitrile groups with a substituted 2‐amino alcohol or 2‐amino phenol resulted in a conversion of nitrile groups of 55–75% in 60 min. The introduced heterocyclic structures were ethyl hydroxymethyl oxazoline (EHMOXA) and benzoxazole (BenzOXA), respectively. The use of dibutyltin oxide as a catalyst led to the highest efficiency. The modified polymer was characterized by Fourier transform infrared and NMR spectroscopy, elemental analysis, and reactions with organic acids and anhydrides. The modified S/AN showed good technical compatibility (single glass‐transition temperature) with PC in blends made from solution and from the melt. All blends were characterized with oscillating rheometry and differential scanning calorimetry. Rheological measurements showed that EHMOXA–S/AN reacted with PC and had crosslinked structures, whereas BenzOXA–S/AN showed compatibilization without any (crosslinking) reaction. The melt blends of BenzOXA–S/AN and PC showed a downward shift in the complex viscosity due to the influence of the BenzOXA group. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2322–2332, 2003     

双酚酸合成及应用研究进展

利用乙酰丙酸和苯酚缩合反应制取双酚酸.本文介绍了其合成工艺进展及在环氧树脂、聚碳酸酯、水溶性树脂、超支化聚酯生产中的应用.最后展望了双酚酸生产工艺的发展前景,同时对我国双酚酸的研究与开发提出了建议.     

Nanoscratch testing to assess the fiber adhesion of short‐carbon‐fiber composites

In a composite material, the degree of adhesion between the fiber and the matrix plays an important role in the overall performance of the material. Because the load between the fiber and the matrix is realized throughout the interphase region material, a lot of effort has gone into characterizing the strength of the interphase. In this study, nanoscratch tests on the composite samples were used to provide a relative measure of adhesion in different composite materials. Carbon‐filled nylon 6,6 and polycarbonate resins were evaluated with this method. The carbon fillers we used were polyacrylonitrile‐based carbon fibers sized and surface‐treated for the respective matrix and pitch‐based carbon fibers without any sizing or surface treatment. Tensile and X‐ray photoelectron spectroscopy data for the composites we considered are also presented to compare to the nanoscratch results. It is shown that nanoscratch testing on the composites, with the proposed data analysis, can be an effective tool for determining the relative degree of adhesion between different composites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 328–335, 2007     

Study on the changing regularity of structure and properties of PC aged outdoor in western areas of China

As an important engineering material, polycarbonate (PC) has been used widely. When exposed to the environment, PC will have aging process, which will reduce its performance and efficiency. This article studies the changing regularities of PCs structure and properties of ageing in western areas of China by measuring the change of intrinsic viscosity (IV), thermal decomposition temperature, glass transition temperature, and the groups within PC. The analysis of its IV, DSC, and thermo gravimetric analysis exhibited the same changing regularity, i.e., the aged PC (in Lasa, Yuli, and Jiangjin) experienced degradation and crosslinking, while degradation occurred earlier in the process of ageing, crosslinking predominated in later period. In addition, the results of UV absorption spectra and infrared absorption spectra showed the evidence of decomposition of the ester groups, resulting in the production of alcohol and phenol. And the results of mechanical tests indicated that the ductility disappeared mainly in the first year of outdoor aging. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Enhancement of physical and optical performances of polycarbonate‐based diffusers for direct‐lit LED backlight unit by incorporation of nanoclay platelets

Using twin‐extrusion compounding followed by compression molding processes, polycarbonate/clay nanocomposite optical diffusers with highly intercalated and exfoliated nanostructure could be prepared for application in direct‐lit LED backlight unit. The incorporation of nanoclay platelets with an appropriate level of content substantially improved thermal resistance, as well as thermo‐mechanical, and mechanical flexural properties. The optical property of luminance uniformity with respect to both location and viewing angle was also enhanced by the load of nanoclay platelets along with silicone bead, probably due to efficient scattering and diffusion action of the nanoclay. However, excess loading of nanoclay had insignificant effect on the improvement of properties for the nanocomposite diffusers. In addition, the presence of nanoclay platelets in the PC matrix effectively suppressed the moisture absorption rate, suggesting the feasibility of avoiding the warpage phenomena of the optical diffuser during use. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42973.