Polybutylene-terephthalate

Polycarbonates insulating and other electrical properties are excellent and remain almost unchanged by temperature and humidity conditions. One exception is arc resistance, which in PCs is lower than in many other plastics. They are generally unaffected by greases, oils, and acids. Water at RT has no effect on PCs, but continuous exposure in 65 C (150°F) water causes gradual embrittlement. They are soluble in chlorinated hydrocarbons and attacked by most aromatic solvents, esters, and ketones, which cause 

The applications of PCs are extensive, emanating into all types of markets. A sample would include electronic connectors, switches, terminal blocks, computer disc packs, storage modules and housings, appliance power-tool housings, vacuum cleaner impellers, fan and air-conditioner grills, automotive instrument panels, indoor and outdoor lighting diffusers, medical kidney dialysers and blood oxygenators, and a host of others. 

There are both thermoplastic and thermoset polyesters, with many of each type each having their own special qualities. 

The two major TPs are polybutylene terephthalates (PBT) and polyethlene terephthalates (PET). These crystalline, high-molecular-weight polymers h ive an excellent balance of properties and processing characteristics. Unreinforced and glass-fiber-reinforced grades 

Some examples of applications for PBTs include automotive distributor caps and painted exterior body components, electronic terminal blocks, coil forms, integrated circuit carriers, and other electromechanical parts to replace thermosets. The high-stiffness resins, including the foam injection-molded grades, are well suited for such structural applications as automobile parts. 

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Butanediol [110-63-4] (BDO) goes primarily into tetrahydrofuran [109-99-9] (THE) for production of polytetramethylene ether glycol (PTMEG), used ia the manufacture of polyurethane fibers, eg, Du Font s Spandex. THE is also used as a solvent for PVC and ia the production of pharmaceuticals (qv). Lesser amounts of BDO are employed ia the production of polybutylene terephthalate resias and y-butyrolactone. 

Following the tolerance stack through the end assembly, the bobbin dimension of 22 mm from the outside face to the back face of the magnetic pole is analysed next. This characteristic dimension does not include the tolerance on the impact extruded pole. The pole is to be moulded into the bobbin and the pole face is considered to be part of a mould related dimension. The bobbin is injection moulded using 30% filled polybutylene terephthalate (PBT). The tolerance assigned to the bobbin dimension is 0.035 mm. 

In a molded polymer blend, the surface morphology results from variations in composition between the surface and the bulk. Static SIMS was used to semiquan-titatively provide information on the surface chemistry on a polycarbonate (PC)/polybutylene terephthalate (PBT) blend. Samples of pure PC, pure PBT, and PC/PBT blends of known composition were prepared and analyzed using static SIMS. Fn ment peaks characteristic of the PC and PBT materials were identified. By measuring the SIMS intensities of these characteristic peaks from the PC/PBT blends, a typical working curve between secondary ion intensity and polymer blend composition was determined. A static SIMS analysis of the extruded surface of a blended polymer was performed. The peak intensities could then be compared with the known samples in the working curve to provide information about the relative amounts of PC and PBT on the actual surface. 

Fig. 11. Effect of polyolefin primers on bond strength of ethyl cyanoacrylate to plastics. All assemblies tested in accordance with ASTM D 4501 (block shear method). ETFE = ethylene tetrafluoroethylene copolymer LDPE = low-density polyethylene PFA = polyper-fluoroalkoxycthylene PBT = polybutylene terephthalate, PMP = polymethylpentene PPS = polyphenylene sulfide PP = polypropylene PS = polystyrene PTFE = polytetrafluoroethylene PU = polyurethane. From ref. [73].

FIGURE 9.27 Analysis of recycled polybutylene terephthalate. Columns PSS PFG 100 + 1000. Eluent HFIP. Temp 2S°C. Detection UV 254 nm, Rl. Calibration PSS PBT standards (broad). 

PBT - polybutylene terephthalate PDMS - polydimethyl siloxane rubber PE - polyethylene PET - polyethylene terephthalate PHB - poly[D(-)]-3-hydroxy butyrate PP - polypropylene... 

Polybutylene terephthalate (PBT) is another thermoplastic polyester produced by the condensation reaction of terephthalic acid and 1,4-butanediol ... 

Polybutylene terephthalate/polyethylene terephthalate Lower cost... 

Deak G. and Kennedy J.P., Copolyesters containing polyisobutylene soft segments and polybutylene terephthalate as crystalline segments, MacrolmoL Rep., A33(Suppls 7 8), 439, 1996. 

C13-0055. Polybutylene terephthalate, used to make countertops and sinks, has the following stmcture. Draw the stmctural formulas of the monomers from which this polymer is made. 

Polyesters, which are a class of engineering thermoplastics, are found in a wide variety of applications including carbonated drink bottles, fibers for synthetic fabrics, thin films for photographic films and food packaging, injection molded automotive parts, and housings for small appliances. In this chapter, we svill explore the synthesis of this class of polymers. We will also look at the typical properties and end uses for the most common of these resins, polyethylene terephthalate and polybutylene terephthalate, which are commonly known as PET and PBT, respectively. 

Polyesters form via a condensation reaction between a dicarboxylic acid and a dialcohol to create an ester linkage, as shown in Fig. 24.1. By far, the two most common polyesters are polyethylene terephthalate and polybutylene terephthalate, the chemical structures of which are shown in Fig. 24.2. These two polymers differ from one another by the length... 

In addition to the desired polymerization reaction, the dialcohol reactants can participate in deleterious side reactions. Ethylene glycol, used in the manufacture of polyethylene terephthalate, can react with itself to form a dialcohol ether and water as shown in Fig. 24.4a). This dialcohol ether can incorporate into the growing polymer chain because it contains terminal alcohol units. Unfortunately, this incorporation lowers the crystallinity of the polyester on cooling which alters the polymer s physical properties. 1,4 butanediol, the dialcohol used to manufacture polybutylene terephthalate, can form tetrahydrofuran and water as shown in Fig. 24.4b). Both the tetrahydrofuran and water can be easily removed from the melt but this reaction reduces the efficiency of the process since reactants are lost. 

Both polyethylene terephthalate and polybutylene terephthalate exhibit partial crystallinity in the solid state. The molecular weight of the polymer and the time permitted for cooling define the degree of crystallinity of the polymer. Very slow cooling results in high crystallinity and opacity, while fast quenching creates low crystallinity, high clarity material. 

Polyethylene terephthalate is most often extruded into films or fibers, or blow molded into bottles. Polybutylene terephthalate is primarily found in injection molded parts. Such parts are highly crystalline, which makes them opaque. Polybutylene terephthalate is often modified with glass fibers or impact modifiers. Table 24.1 contains applications by processing method and resin. 

Table 24.1 Applications of polyethylene terephthalate and polybutylene terephthalate by processing method...

Injection molding grades of polyethylene terephthalate and polybutylene terephthalate have low melt viscosities. Because of this, they can be used to manufacture intricate parts within... 

Typically, polyester resins are used for high-end applications that require excellent electrical and thermal resistance. When dimensional stability under load is more critical, glass fibers are incorporated to increase the heat distortion temperature and the stiffness of the part. Examples of glass fiber reinforced parts include electrical housings, electrical adapters, computer components, telephone housings, and light bulb sockets. When impact modified, polybutylene terephthalate can be injection molded to make car bumpers. 

Polyesters exhibit excellent high temperature strength and electrical properties making them a good choice for many demanding applications. They also are physiologically inert allowing them to be used in food contact applications. The two common polyesters, polyethylene terephthalate and polybutylene terephthalate, are both used in injection molded products. Polyethylene terephthalate is often used in both extrusion and blow molded processes also. 

How do polyethylene terephthalate and polybutylene terephthalate differ from one another chemically How do these differences affect their properties ... 

What properties of polybutylene terephthalate make it amenable to injection molding processing ... 

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