Amorphous polycarbonate composites

Lin and coworkers [41] also investigated the static tensile strength and fatigue behavior of long glass-reinforced semicrystalline polyannide and amorphous polycarbonate composites. The static tensile measurement at various tanperatures and tension-tension fatigue loading tests at various levels of stress amplitudes were studied. 

By chromophore-polymer composite materials, we refer to chromophores physically incorporated (dissolved) into commercially available polymer materials such as amorphous polycarbonate (APC) [58] finm Aldrich Chemicals. Chromophore and polymer are dissolved in a suitable spin-casting solvent, such as cyclopentanone. Spin-cast thin films are heated to near the glass transition temperature of the composite material (which will vary with chromophore concentration due to the plasticizing effect of the chromophore). Acentric chromophore order is induced by electric field poling. If one assumes that the presence of the polymer host does not stericaUy hinder the reorientation of the chromophores under the influence of the poling field, the order parameter can be readily calculated. We have already noted that if chromo-phore-chromophore intermolecular electrostatic interactions are neglected then (cos d) = fiF/5kT and the order parameter will be independent of chromophore concentration (or number density, N). Intermolecular electrostatic interactions can be treated at several levels of sophistication. 

As Carfagna et al. [61] suggested, the addition of a mesophasic polymer to an amorphous matrix can lead to different results depending on the properties of the liquid crystalline polymer and its amount. If a small amount of the filler compatible with the matrix is added, only plasticization effect can be expected and the dimensional stability of the blend would be reduced. Addition of PET-PHB60 to polycarbonate reduced the dimensionality of the composite, i.e., it increased the shrinkage [42]. This behavior was ascribed to the very low... 

Composition (type of polymeric components). The base polymer (which is to be modified) may be an amorphous polymer [e.g., polystyrene (PS), styrene-acrylonitrile copolymer, polycarbonate, or poly(vinyl chloride)], a semicrystalline polymer [e.g., polyamide (PA) or polypropylene (PP)], or a thermoset resin (e.g., epoxy resin). The modifier may be a rubber-like elastomer (e.g., polybutadiene, ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, or ethylene-propylene-diene copolymer), a core-shell modifier, or another polymer. Even smaller amounts of a compatibilizer, such as a copolymer, are sometimes added as a third component to control the morphology. 

An empirical method for predicting the chemical compositions of random or partially ordered condensation copolymers which are capable of exhibiting mesophases (either in solution or in the melt) was devised by the author in 1989, while working on liquid crystal copolymer synthesis for BP Chemicals. A brief description of the method and its application to the chemical synthesis of amorphous thermotropic polyamides has been given in a previous paper [45] and a further more detailed description of the method is to be published shortly [46]. Subsequently, the method has been updated and applied to polycarbonates and polyimides. Thermotropic polyimides have also been synthesised by the author resulting from the use of the predictive method [43]. 

Physical blends of bisphenol-A polycarbonate (PC) and a poly-arylate (PAr) exhibit by thermal analysis two amorphous phases a pure PC phase and a PAr-rIch miscible mixed phase. On controlled thermal treatment, transreaction between PC and PAr takes place mainly in the mixed phase, producing a new copolymer. Reaction progression from block to random copolymers has been traced by DSC, 13c NMR and CPC. The final product of transreaction is an amorphous copolymer showing a single T depending on the original binary composition. ... 

Like resin materials (such as ABS-to-ABS) are the easier to weld ultrasonically, but some unlike resins may he bonded provided they have similar melt temperatures, chemical composition, and modulus of elasticity. Generally, amorphous resins (ABS, PPO, and polycarbonate) are also easier to weld ultrasonically than crystalhne resins (nylon, acetal, thermoplastic polyester). 

In the case of polycarbonate the addition of PET/PHB60 reduces, at high temperature,the dimensional stability of the composite blend. In fact the temperature of the shrinkage experiments is higher than the glass transition temperature of the LCP (35). In this case the nematic inclusions cannot act as solid fibers, but on the contrary act as internal lubricant particles, due to the low viscosity of the nematic phase, allowing then the complete relaxation of the amorphous matrix. 

Typical creep curves for polyethylene (PE) and polypropylene (PP) at 23 °C are shown in Figures 18.2 and 18.3. Lin and co-workers [1] have discussed creep phenomena accuracy in reinforced polyamide (PA) and polycarbonate (PC) composites. The phenomenon of the increasing dynamic creep property and the temperature under tension-tension fatigue loading are compared between semi-crystalline and amorphous composites. 

Typical curves for polyethylene and polypropylene at 23°C are shown in Figures 2.2 and 2.3. Lin and coworkers [41] discussed the accuracy of creep phenomena in reinforced PA and polycarbonate (PC) composites. In this paper, the phenomenon in increasing dynamic creep and temperature under tension-tension fatigue loading is compared between semicrystalline and amorphous composites. 

The first blends studied on polyesters based on 1,4-CHDM were made of the amorphous copolyester of terepthalic and isophthalic acids and 1,4-CHDM (PCTA) and polycarbonate of bisphenol A (126). The single displayed for the whole range of compositions was taken as demonstrative of full miscibility, which is explained as due to the positive physical interactions between the polyester and the polycarbonate. PCTA is also miscible with a copolycarbonate of bisphenol A and l,l-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclo hexanone (TMC) for all compositions except for those involving a polycarbonate entirely made of TMC (127). 

PCT has been blended with other miscible or compatible polymers in order to decrease its melting temperature and to improve its processability. Hwang (132) blended it with an aromatic amorphous copolyester made from bisphenol A and isophthalic/tere-phthalic acids, which is called Polyarylate (PAR). These blends were miscible in all range of compositions, as demonstrated by the existence of a single, composition dependent T. A decrease in melting temperature and enthalpy was observed for increasing amounts of PAR in the blend. PCT was also miscible with polycarbonate of bisphenol A, as revealed by DSC and solid state deuterium NMR spectroscopy (133). The crystallization of PCT /PC blends in microlayers and blends has been also studied (134). 

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