Engineered polycarbonate blends

Triphenyl phosphate [115-86-6] C gH O P, is a colorless soHd, mp 48—49°C, usually produced in the form of flakes or shipped in heated vessels as a hquid. An early appHcation was as a flame retardant for cellulose acetate safety film. It is also used in cellulose nitrate, various coatings, triacetate film and sheet, and rigid urethane foam. It has been used as a flame-retardant additive for engineering thermoplastics such as polyphenylene oxide—high impact polystyrene and ABS—polycarbonate blends. 

In the engineering polymer blends, a number of advances in the technology and the commercial areas have been realized in the past decade. New commercial polymers have been manufactured by various combinations of preexisting polymers. One of the major areas has been with polyesters and polycarbonates (polybutyleneterephthalate/ polycarbonate polyethyleneterephthalate/polycar-bonate polyarylate/polycarbonate cyclohexane dimethanol based polyesters/polycarbonate). 

Tetraphenyl Resorcinol Diphosphate [57583-54-7], This is the main component of an oligomeric phosphate flame retardant, Akzo Nobel s FYROLFLEX RDP or Great Lakes Chemical s REOFOS RDP, designed for use in engineering thermoplastics such as polyphenylene oxide blends (105,106), thermoplastic polyesters, polyamides, polycarbonates, and ABS-polycarbonate blends. A major use was in PPO-HIPS blends and later in ABS-polycarbonate blends (107). It is a colorless to light-yellow liquid, viscosity 400-800 mPa s at 25°C, and a pour point of - 12°C. It is less volatile than the triaryl phosphates and has a higher percentage of phosphorus (11% P) than triphenyl phosphate. 

Thanks to their unusual miscibility polymer blends of polyphenylene oxide and polystyrene were the first commercially successful amorphous engineering thermoplastics blends, introduced back, in 1968 Pete Juliauo of GE Corporate Research Laboratories presented a comprehensive review at the last lUPAC Meeting of The Rague(l) where he showed how the evolution of science and technology of blends (2,3) based on polyphenylene oxide, blsphenol A polycarbonate, polybutylene teraphthalate, polyamides and polyacetals, created many more opportunities for the development of engineering thermoplastics with attractive combination of attributes. 

The history of Xenoy PC/PBT commercial engineering thermoplastics blends is still rather recent in the late sixties, early seventies many activities in blending polycarbonate with polyesters took place, leading to over 120 patents and many academic studies, but very few products. 

Engineering resins can be combined with either other engineering resins or commodity resins. Some commercially successhil blends of engineering resins with other engineering resins include poly(butylene terephthalate)—poly(ethylene terephthalate), polycarbonate—poly(butylene terephthalate), polycarbonate—poly(ethylene terephthalate), polysulfone—poly (ethylene terephthalate), and poly(phenylene oxide)—nylon. Commercial blends of engineering resins with other resins include modified poly(butylene terephthalate), polycarbonate—ABS, polycarbonate—styrene maleic anhydride, poly(phenylene oxide)—polystyrene, and nylon—polyethylene. 

Engineering polymers are often used as a replacement for wood and metals. Examples include polyamides (PA), often called nylons, polyesters (saturated and unsaturated), aromatic polycarbonates (PCs), polyoxymethylenes (POMs), polyacrylates, polyphenylene oxide (PPO), styrene copolymers, e.g., styrene/ acrylonitrile (SAN) and acrylonitrile/butadiene/styrene (ABS). Many of these polymers are produced as copolymers or used as blends and are each manufactured worldwide on the 1 million tonne scale. 

Mixed esters, such as isopropylphenyl diphenyl phosphate and tcrt-butylphenyl diphenyl phosphate, are also widely used as both plasticizers/flame retardants for engineering thermoplastics and hydraulic fluids.11 These esters generally show slightly less flame-retardant efficacy, when compared to triaryl counterparts however, they have the added advantage of lower smoke production when burned. Some novel oligomeric phosphate flame retardants (based on tetraphenyl resorcinol diphosphate) are also employed to flame retard polyphenylene oxide blends, thermoplastic polyesters, polyamides, vinyls, and polycarbonates. 

To the range of engineering plastics were added polyethylene and polybutylene tereph-thalates (PET and PBT), as well as General Electric s polyethers, the PPO (polyphenylene oxide) produced through polymerization of 2,6-xylenol and the Noryl plastic produced by blending PPO with polystyrene. Other special polymers, derived like the polycarbonates from bisphenol A, were added to this range polyarylates, polysul-fones, polyetherimides. 

Chen and Gardella used this surface engineering strategy to create siloxane-rich surfaces [40]. Their approach involved the blending of a homopolymer (A) with a block copolymer composed of a block with the same chemical identity as the homopolymer (A) and a block of PDMS. For all homopolymer types studied (polystyrene, poly(cc methyl.styrene) and Bisphenol A polycarbonate), XPS analysis of Si C ratios revealed a significant enrichment of the PDMS... 

Although polycarbonate is an engineering thermoplastic material which provides high toughness, flexibility and thermal stability, it suffers from certain limitations due to poor chemical resistance and low flow characteristics in injection moulding. These shortcomings can be circumvented by blending PC... 

Fortunately, the deficiencies of both the classic thermosets and general purpose thermoplastics have been overcome by the commercialization of a series of engineering plastics including polyacetals, polyamides, polycarbonate, polyphenylene oxide, polyaryl esters, polyaryl sulfones, polyphenylene sulfide, polyether ether ketones and polylmides. Many improvements in performance and processing of these new polymers may be anticipated through copolymerization, blending and the use of reinforcements. 

Polycarbonate of bisphenol-A (PC) is recognized as an engineering, amorphous polymer. However, there are many reports that PC does crystallize in blends with, e.g., PCL [Jonza and Porter, 1986], and other polymers [Utracki, 1998]. 

The general motivation for blending styrenic resins with other polymers, particularly with the higher priced engineering resins, such as polycarbonate or polyphenylene ether, is primarily to lower the cost and improve the processability of the latter resins. As far as styrenic resins are concerned, some of the reasons for blending stem from the need to improve their property deficiencies, viz. solvent resistance, impact strength, heat resistance and flame resistance. 

Polyetherimide (Ultem 1000, GEC) is a high performance engineering thermoplastic with high heat distortion temperature (> 200°C), high mechanical strength and inherent flame-retardancy characteristics. Recently blends of polyetherimide with polycarbonate have been commercially offered as thermoformable sheets and as molding compounds (Table 15.28). The primary reason for... 

PPE/HIPS blends filled the price-performance gap between the styrenic resins (HIPS, ABS) and the engineering resins such as polycarbonate, polyarylate and polysulfones. The technology and applications of PPE/HIPS blends have already been discussed under the styrenic resin blends section (Table 15.3). 

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