Polybutylene terephthalate chemical resistance

Chemical Resistance - Styrene Maleic Anhydride / Polybutylene Terephthalate Alloy... 

The most important commercial blends of BPA-PC are poly(acrylonitrile-butadiene-styrene) (PC/ABS) and polybutylene terephthalate (PC/PBT) or polyethylene terephthalate (PET). Commercial grades of PC/ABS include CYCOLOY (GE), Bayblend (Bayer), and PULSE (Dow). PC/ABS blends exhibit improved flow and processability and enhanced low-temperature impact strength in comparison to PC (Fig. 3). These blends are widely used in applications requiring enhanced impact resistance, such as interior automotive parts and computer and electronics applications such as computer housings and cell phones. Non-halogenated flame-retardant PC/ABS blends are widely available. Poly(acrylic-styrene-acrylonitrile) (PC/ ASA) blends (GELOY , GE Luran , BASF) provide improved weatherability for outdoor applications such as exterior automotive parts, but exhibit reduced impact performance at low temperatures in comparison to PC/ABS. PC/PBT or PET blends (XENOY , GE Makroblend , Bayer) provide enhanced chemical resistance and weatherability for applications such as lawn and garden equipment and automotive bumpers and fasdas. 

PET/PBT (polyethylene terephthalate/polybutylene terephthalate) good colorabUity, excellent surface aesthetics, gloss, chemical resistance, impact, and electrical properties. Apphcations include appliances, electrical apphcations, building and construction. 

Thermoplastic polyesters include polybutylene terephthalate (PBT), which possesses good slip and wear properties, resists chemicals and hydrolysis, and has excellent dimensional stability. Mechanical parts in drug delivery and filter systems are preferably made of PBT. 

The second most important class of commercial polycarbonate blends is derived by blending with commercial thermoplastic polyesters such as polybutylene tere-phthalate (PBT) and polyethylene terephthalate (PET). Both PBT and PET are crystallizable polymers and hence offer the expected chemical resistance advantages of the crystalline polymers in blends with polycarbonate. Among the thermoplastic polyester/polycarbonate blends, the PBT/PC blend has the major commercial volume, followed by the PET/PC blend. A copolymer of 1,4-cyclohexanedimethanol, ethylene glycol, and terephthalic acid (PCTG) forms a miscible blend with polycarbonate. PCTG/PC blend was earlier offered by Eastman (Ektar ) for specialty applications, but it is no longer commercial. 

Crystalline polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT) for significantly improved chemical resistance... 

Chapter 7, Polybutylene Terephthalate, from LG Chem, describes the science and technology of PBT blends, compounds, and composites. The chapter offers details on the advantages of different polymer blends, types of fiber, and mineral and fiber-mineral hybrid reinforcements as well as chemical and hydrolysis resistance, flammability, and other PBT attributes. The author states that the most important apphcations of PBT are automotive and electrical, electronics and telecommunications, as well as precision engineering and general mechanical engineering, and concludes that the ability to modify for various applications, combined with a range of reinforcement and blend, has enabled PBT as one of the most widely used engineering polymers. ... 

Polybutylene terphthalate (PBT) is a semicrystalline thermoplastic polyester considered as a medium performance engineering polymer. It is produced industrially in a two-step batch or continuous process. The first step involves the transesterification of dimethyl terephthalate (DMT) with 1,4-butanediol (BDO) to produce hydrobutyl terephtlate (bis-HBT) at a temperature of 200 C. The second step consists to the polycondensation of bis-HBT at 250 C to yield PBT. It exhibits both excellent electrical properties and chemical resistance. When reinforced with glass fibers, it has improved stiffness and mechanical strength. Typical uses include connectors, capacitors and cable enclosures. PBT is also used in hot appliances such as iron and kettles. 

PC, though tough and able to withstand very high temperatures, lacks good resistance to chemicals polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) make up for this lack Alloying with PET lowers PBT s impact resistance but brings down its cost Polyvinyl chloride (PVC) adds flame... 

Exterior door handles are another application that has turned to plastics to balance chemical resistance and mechanical properties. Many filled thermoplastics such as blends of PC and polybutylene terephthalate (PBT), polyethylene terephthalate (PET), and nylon have been tried or used in this application, with nylon as the clear wirmer. Exterior mirror housings likewise use many thermoplastic solutions such as ABS, PC/ABS, blends of polyphenylene oxide (PPO) and polystyrene (PS), nylon, blends of PP and ethylene propylene diene monomer (EPDM), and weatherable ABS. Again, nylon clearly dominates this application in terms of volume. Many other exterior parts continue to adopt thermoplastic solutions. Figure 14 shows an impingement shield constructed from LGF PP. 

The semi-crystalline character of polybutylene terephthalate and polyethylene terephthalate is the reason for their good resistance to chemicals. Organic solvents, such as aliphatic hydrocarbons, fuels, alcohols, ethers, long-chain esters, fats, oils, perchlorinated hydrocarbons, and the fiuorinated hydrocarbons used in aerosol technology do not attack thermoplastic polyesters at room temperature. These plastics are also resistant to weak acids, weak bases, water, and to aqueous solutions of neutral and acid salts at room temperature. However, they are non-resistant to strong acids, oxidizing acids, strong bases, ketones, and phenols. 

Polybutylene terephthalate (PBT) is a semi-crystalline saturated polyester, which has been produced since 1942. PBT is made by the polycondensation of terephthalic acid or dimethyl terephthalate with 1,4-butanediol in the presence of a catalyst. Terephthalic acid, dimethyl terephthalate and 1,4-butanediol are derived from petrochemicals such as xylene and acetylene. The polymer is noted for high stiffness and strength, high resistance to heat, low water absorption and high dimensional stability. It has moderate chemical resistance and low resistance to strong acids and bases. 

In 1998, BASF was the first producer to develop a halogen-free, flame-retardant polybutylene terephthalate (PBT), which retains the key properties of PBT, namely dimensional stability, chemical resistance and good toughness. The material is supplied under the brand name Ultradur B 4000 . Compared with PBT that contains halogen, it offers a low smoke density and a very high tracking resistance. 

The choice of substrate can impact the chemical and etch resistance of a coated plastic part. Thin layers of paint (especially when thin) can be influenced by the hardness of the substrate. However, this does not generally impact the chemical resistance of clear-coated parts as measured in testing such as Jacksonville. Substrates that are sensitive to solvents such as acrylonitrile butadiene styrene (ABS) and polycarbonate/polybutylene terephthalate (PC/PBT) can be rapidly or slowly degraded when attacked with certain solvents or even basic materials. 

Polybutylene Terepbtbalate Thermoplastic polymer of dimethyl terephthalate and butanediol. Has good tensile strength, dielectric properties, and chemical and water resistance, but poor impact strength and heat resistance. Processed by injection and blow-molding, extrusion, and thermo forming. Used in auto body parts, electrical devices, appliances, and housings. Also called PBT. 

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