Polycarbonate homopolymers

The TMC polycarbonate homopolymer has a glass transition temperature of 238°C, nearly 100°C above that of the bis-phenol A polycarbonate. Therefore, copolymers will have intermediate glass transitions depending on the relative proportions of TMC and bis-phenol A. Commercial grades (marketed by Bayer as Apec HT) have Vicat softening points from 158 to... 

The quantitative analysis of additives in a polycarbonate homopolymer has been carried out by micro-SEC-capillary GC and by a conventional precipitation technique (14). The validity of the on-line technique was demonstrated and equivalent... 

Fig. 3. ESCA results on the surface segregation of the Polycarbonate homopolymer/Poly-carbonate-Polydimethylsiloxane segmented copolymer blends 1S0)...

Cortes et al. [18] have quantitatively determined polymer additives in a polycarbonate homopolymer and an ABS terpolymer. In that case, a multidimensional system consisting of a microcolumn SEC was coupled on-line to either capillary GC or a conventional LC system. The results show losses of certain additives when using the conventional precipitation approach. An at-column GC procedure has been developed for rapid determination (27 min) of high-MW additives (ca. 1200Da) at low concentrations (lOOppm) in 500- xL SEC fractions in DCM for on-line quality control (RSD of 2-7%) [36], Also, SEC-NPLC has been used for the analysis of additives in dissolution of polymeric... 

Since the introduction of BPA polycarbonate homopolymer, researchers have continually sought to expand the usefulness of these materials via synthesis of new polycarbonate homo- and copolymers. This section will focus on the copolymers that are commercially available. For a more extensive examination of noncommercial, non-BPA polycarbonates, several excellent reviews may be found at [90-93]. Copolymer production generated by reactive blending, coextrusion, and/or compatibilizing materials (e.g., grafting) will also not be discussed. However, a historical overview of commercial alloys and blends may be found in a recent work by Utracki [94]. 

Figure 14.7 Comparison of copolyestercarbonate resins vs. polycarbonate homopolymer resins [129].

In applications requiring higher thermal performance, a polyester-carbonate copolymer has been developed with an HDT that is 28°C (50°F) higher than that of standard polycarbonate homopolymers (see the section Polyestercarbonates and Other High-Heat Polycarbonates ). The most common use of this material occurs in automotive headlamp applications, where the copolymer forms the metallized reflector, and in animal cages that require repeated autoclave sterilization. 

For applications where polycarbonate homopolymers or copolymers lack sufficient thermal performance, blends with polyetherimide (PEI) are often used. PEI, which also contributes excellent flammability and low smoke generation to the alloy, may be combined with either straight polycarbonate or polycarbonate blends, depending on what other properties are required. The most common uses are found in light reflectors for automotive headlamps, components for aircraft interiors (especially wall and ceiling panels), and food-contact applications for microwave-to-table cookware. 

Polycarbonate homopolymer when exposed to heat and humidity, under some eonditions may suffer a reduction in the meehanical properties. This paper discusses significantly improved heat and hydrolytie resistance of eopolymers of Polycarbonate with Polysiloxane. Retention of transparenQr conpled with good mechanieal properties upon heat and hydrolytie aging makes these new materials excellent candidates for hot and hnmid engineering thermoplastic apphcations. 

Whilst the Vicat test usually gives the higher values the differences are quite modest with many polymers (e.g. those of types A, B and C). For example, in the case of the polycarbonate of bis-phenol A (Chapter 20) the heat distortion temperatures are 135-140°C and 140-146°C for the high and low stress levels respectively and the Vicat softening point is about 165°C. In the case of an acetal homopolymer the temperatures are 100, 170 and 185°C respectively. With nylon 66 the two ASTM heat distortion tests give values as different as 75 and 200°C. A low-density polyethylene may have a Vicat temperature of 90°C but a heat distortion temperature below normal ambient temperatures. 

Further variations in the polycarbonate system may be achieved by copolymerisation. The reduced regularity of copolymers compared with the parent homopolymers would normally lead to amorphous materials. Since, however, the common diphenylol alkanes are identical in length they can be interchanged with each other in the unit cell, providing the side groups do not differ greatly in their bulkiness. 

Statistical copolymerization of ethylene glycol and 1,4-butanediol with dimethyl ter-ephthalate results in products with improved crystallization and processing rates compared to poly(ethylene terephthalate). Polyarylates (trade names Ardel, Arylon, Durel), copolymers of bisphenol A with iso- and terephthalate units, combine the toughness, clarity, and proce-sibility of polycarbonate with the chemical and heat resistance of poly(ethylene terephthalate). The homopolymer containing only terephthalate units is crystalline, insoluble, sometimes infusible, and difficult to process. The more useful copolymers, containing both tere- and isophthalate units, are amorphous, clear, and easy to process. Polyarylates are used in automotive and appliance hardware and printed-circuit boards. Similar considerations in the copolymerization of iso- and terephthalates with 1,4-cyclohexanedimethanol or hexa-methylene diamine yield clear, amorphous, easy-to-process copolyesters or copolyamides,... 

Core-shell emulsion polymers with a core or rubbery stage based on homopolymers or copolymers of butadiene are used as impact modifiers in matrix polymers, such as ABS, for styrene acrylonitrile copolymer methyl methacrylate (MMA) polymers, poly(vinyl chloride) (PVC), and in various engineering resins such as polycarbonate) (PC) poly(ester)s, or poly(styrene)s, further in thermosetting resins such as epoxies. 

Plastics for which the adhesion of coatings may be improved by plasma pre-treatment are reported to be polyethylene, polypropylene, polycarbonates, polyacetals, polyaromatic esters, polyimides, polyamides, polyphenylene ether, polyacrylates, acetal homopolymer, and poly(ether imide). 

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