Polyester plastic liquid-crystal

Liquid crystal polymers (LCP) are a recent arrival on the plastics materials scene. They have outstanding dimensional stability, high strength, stiffness, toughness and chemical resistance all combined with ease of processing. LCPs are based on thermoplastic aromatic polyesters and they have a highly ordered structure even in the molten state. When these materials are subjected to stress the molecular chains slide over one another but the ordered structure is retained. It is the retention of the highly crystalline structure which imparts the exceptional properties to LCPs. 

Aortal Aery Me ABS Alkyd Alloy /Blands Barrier Resin CeliAwie Diallyl Phthalates Engineering Plastics Epoxies Fluorepdlymars Liquid Crystal Melamine Nitrile Resins Nylon Phenolic Polyamlde-lmide Polycarbonate polyester Polyethylene Polyimictes Polypropylene Polyurethanes PVC... 

Acrylic ester polymers Acrylonitrile polymers Cellulose esters). Engineering plastics (qv) such as acetal resins (qv), polyamides (qv), polycarbonate (qv), polyesters (qv), and poly(phenylene sulfide), and advanced materials such as liquid crystal polymers, polysulfone, and polyetheretherketone are used in high performance applications they are processed at higher temperatures than their commodity counterparts (see Polymers containing sulfur). 

Some of the common types of plastics that are used are thermoplastics, such as poly(phenylene sulfide) (PPS) (see POLYMERS CONTAINING SULFUR), nylons, liquid crystal polymer (LCP), the polyesters (qv) such as polyesters that are 30% glass-fiber reinforced, and poly(ethylene terephthalate) (PET), and polyetherimide (PEI) and thermosets such as diallyl phthalate and phenolic resins (qv). Because of the wide variety of manufacturing processes and usage requirements, these materials are available in several variations which have a range of physical properties. 

The interest of 2,6-dialkylnaphthalenes as starting materials in the production of polyester fibers and plastics with superior properties [1, 2] and of thermotropic liquid crystal polymers [3] is clearly shown by the increasing number of recent patents relevant to their preparation and separation[3.5]. However, the selective formation of 2,6-dialkylnaphthalenes is not obvious, not only with conventional Friedel-Crafts catalysts [6-8], but also over solid catalysts such as silica-alumina [9-11] or zeolites. 

Xydar Amoco Performance Products Inc. s tradename for its family of liquid-crystal polymers, xylene A colorless aromatic hydrocarbon liquid. It is used as a solvent, in the manufacture of polyester plastics, and as a chemical intermediate. 

Petra 140 (Allied Signal) is a 40 percent glass-reinforced polyethylene tereph-thalate from recycled soda bottles. It has a tensile strength of 26,000 psi and a heat-deflection temperature of 225°C at 264 psi. PC23MS-200 (MCR Polymers) contains at least 25 percent recyclate from personal computer compact disks and polyethylene terephthalate beverage bottles. DMDA-1343NT polyethylene (Union Carbide) contains 28 percent color-sorted recyclate and has physical properties similar to those of virgin stock. Encore resins (Hoechst Celanese) are a family of plastics based on 100 percent reclaimed thermoplastics such as acetal, polyester, polyphenylene sulfide, nylon 6/6, and liquid crystal polymer. 

Figure 1 Cost-related (specific) flexural strength of major thermoplastics, versus cost-related (specific) thermal tolerance. The unit cost is the market price in US cents (1992) of 1 cm plastics. The thermal tolerance is the temperature difference (AT) over room temperature (AT — T - room T), by which temperature (7 ) the flexural modulus is equal to 1 GPa. Designations, abbreviations WFRP-S, wood fiber reinforced PP (S type) of AECL, Canada (See Table 1) PMMA, polymethylmethacrylate PVC, pol)winyl chloride PS, polystyrene PP, polypropylene UP, unsaturated polyesters PA-GF, glass fiber (35%) reinforced polyamide PHR, phenolic resin EP, epoxy resin ABS, acrylonitrile/butadiene/styrene copolymer UF, urea/formaldehyde LDPE, low density polyethylene PC, polycarbonate POM, polyoxymethylene CAB, cellulose acetate butyrate LCP, liquid crystal polymers PEEK, polyether-etherketone PTFE, polytetrafluorethylene.

A liquid-crystal display (LCD) using polarizers as the panel substrate is investigated to find its application possibility. The optical properties of LCD using biaxially drawn polyester films and uni-axially drawn polyester films are evaluated and it was found that the latter films can be used as supporting films of the polarizers. Interference colors may develop due to birefringence, as both uni-axially drawn polyester films and LC molecules are optically anisotropic. Finally, the developed plastic LCD is 0.5 mm thick and has better optical characteristics than that of a conventional LCD using glass substrates [146]. 

These thermotropic liquid-crystalhne polymers have high melting points but can be melt-processed like other thermoplastics. The macroscopic orientation of the extended-chain crystals depends on the orientation imparted by flow during processing (molding, extrusion, etc.). Because of the fibrous nature of the extended-chain crystals, these plastics behave as self-reinforced composites, with excellent mechanical properties, at least in the chain direction. This is illustrated in Table 4.3 for molded specimens of a hquid-crystalline copolyester of ethylene glycol, terephthalic acid, and / -hydroxybenzoic acid [14]. In the direction parallel to the flow, the properties listed in Table 4.3 favorably compare with ordinary crystalline thermoplastics (nylons, polyesters) reinforced with up to 30% glass fibers. 

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