Thermoplastic polyesters, addition

Materials used such as stifFer plastics can reduce hysteresis heating. Crystalline TPs for example (the popularly used acetal and nylon) can be stiffened by 25 to 50% with the addition of fillers and reinforcements. Others used include ABS, polycarbonates, polysulfones, phenylene oxides, polyurethanes, and thermoplastic polyesters. Additives, fillers, and reinforcements are used in plastics gears to meet different performance requirements (Chapter 1), Examples include glass fiber for added strength, and fibers, beads, and powders for reduced thermal expansion and improved dimensional stability. Other materials, such as molybdenum disulfide, polytetrafluoroethylene (PTFE), and silicones, may be added as lubricants to improve wear resistance. 

Aromatic carboxylic dianhydride chain extenders (e.g. PMDA) are a low-cost way of converting recycled PET flakes into high-IV crystalline pellets that can be used in high-value applications (e.g. bottles, strapping, foam, engineering alloys/compounds, etc.) (see Figure 14.2). PMDA is an effective chain extension additive for thermoplastic polyesters such as PET and PBT. It is suitable for the following applications ... 

Solid-state polycondensation of thermoplastic polyesters such as PET is therefore both time-consuming and energy-intensive. Recently, additives have been developed to accelerate this process [23, 24], Such additives enable PET with a very high IV to be produced at reduced residence times in the solid-state reactor, with enhanced outputs and at a reduced cost. Such additives accelerate the IV enhancement of PET at low cost. One such SSP accelerator is Irgamod 1425 which when used in PET at levels of between 0.1-0.5wt% gives an SSP acceleration of approximately 50 % (see Figure 14.5). 

Thermoplastic polyesters, PET and PBT also offer the advantages of easy melt processability and good solvent resistance owing to their semicrystalline nature. In addition, PET and PBT are... 

It is probably appropriate to mention at this point that a number of feed materials may need drying before testing, because they either intrinsically take up moisture or contain additives that can promote this effect. Some polymers, notably polyamides and thermoplastic polyesters, will be degraded by processing if they are not dried beforehand under conditions specified by the supplier. 

Du Font s thermoplastic polyester elastomer (TPE) Hytrel has been used in an underwater fiber optic cable produced by Shiplex Wire and Cable Corporation. The elastomer is used to position the fiber optics and is chosen because of its modulus properties that help prevent microbends in the fiber optics. The thermoplastic polyester elastomer is extruded over a central steel wire that imparts strength to the cable. Six fiber optic strands with a diameter of 5 mils each are then positioned and covered by a second Hytrel layer, which is added as part of a coextrusion with nylon to obtain greater abrasion resistance. Additional steel layers and a longitudinally formed copper tape are added, and the whole structure is then enclosed in a polyethylene jacket. 

In addition, there are thermoplastic polyester elastomers. These are produced by equilibrium melt transesteiification of dimethyl terephthalate, 1,4-butanediol, and a poly(tetramethylene oxide) glycol (molecular weight about 10(X)). Because equilibrium conditions exist in the melt, the products are random copolymers ... 

As in the preceding section, the polymers to be bonded were PVC, ABS, and the thermoplastic polyester blend Xenoy. In addition microscope slide glass was also studied. Surfaces of these materials have been shown to be capable of widely differing acid-base interactions. The PVC was an unplasticised polymer (MW = 54,000 g/mol) from Synergistic Chemicals, Inc. It contained 5 phr of Advastab TM-821SP thermal stabiliser. The ABS (Cycolac AR 3501), was a moulding grade, commercial product of GE Plastics, Inc. The same source supplied the Xenoy blend the exact composition of this material was not determined. 

Considerable quantities of PET can be processed to injection-molded forms after addition of nucleation agents, but for this, very exact process conditions must be adhered to. The polymer is rigid, hard, exhibits very little wear and tear, shows very little creep, and can tolerate high mechanical loads. In industry, it is known, together with poly(butylene terephthalate), as a thermoplastic polyester. ... 

Dupont (2007) Addit. Polym., 2007, 2. DupPont (2013) DuPont Hytrel Thermoplastic Polyester Elastomer, http //plastics. dupont. com/plastics/dsheets/hytrel/ GBHYTREL3078.pdf GXHC gx session id =6cSJ32S70 (accessed 29 September 2014). 

Low-molecular-weight HALS, a hydroperoxide inhibitor, has been shown to considerably reduce photooxidation of PBT [107]. It can be expected that the combination of a UV absorber with HALS will be particularly effective. There is little data on stabihzation of thermoplastic polyester elastomers, but the stabilizers used to protect polymers that degrade by free-radical chain oxidations should also be efficient for these types. Thus, UV absorbers of the benzotriazole and benzophenone types may be used for their screening capabihties, and synergistic effects can be expected with the addition of HALS to reduce the rate of chain oxidations. 

BASF has a US patent (US 5712336) in which a thermoplastic polyester is flame-retarded with decabromodiphenylethane and two more additives. These are ... 

Poly(lactic acid) (PLA) is a thermoplastic polyester characterized by mechanical and optical properties similar to polystyrene (PS) and polyethylene terephthalate (PET). It is obtained from natural sources, completely biodegradable and compostable in controlled conditions as already stated in previous chapters. PLA offers some key points with respect to classic synthetic polymers, since it is a bioresource and renewable, while raw materials are cheap and abundant compared to oil. From a commercial point of view, a non-secondaiy approach, it can embellish with the word green so fashioned for the major stream consumers. Legislation can also help the commercial diffusion of biopolymers. As an example, a decisive leap has been made with the control of non-biodegradable shopping bags distribution in the European Commission and many of its member states. In addition, PLA has received some interest from the industrial sectors because of its relatively low price and commercial availability compared with other bioplastics. This is the veiy key point for any successful polymer application. In fact, the current price of commercial PLA falls between 1.5 and 2 kg , which is sufficiently close to other polymers like polyolefins, polyesters or poly(vinyl chloride) (PVC). Clearly, the PLA market is still in its infancy, but it is expected that the decrease in the production costs and the improvement in product performance will result in a clear acceleration in the industrial interest for PLA uses. It is estimated that PLA consumption should reach... 

Other important polymers for the additives business include the styrenics and ABS, the polyesters PET and PBT, the polyamides, acrylics, thermoplastic polyurethanes and thermoplastic elastomers. Additives are widely used in blends too. 

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