Polyester family

Poly(f -caprolactone) (PCL), the most representative member of this polyester family, is obtained by the ring-opening polymerization of e-caprolactone. It is a low-7 (60°C), low-Tg (—60°C) semicrystalline polyester that presents mechanical properties resembling those of low-density polyethylene (Table 2.10). 

Thermoplastic materials of the polyester family, characterised by high impact strength and dimensional stability up to 140 °C. Polychloroprene See Neoprene. 

Additives and copolymers have extended the use of PET fibers into areas where the original commodity products had deficiencies, in, for example, soil-resistance, static protection or poor dyeability. Newer members of the polyester family have found applications in markets where more stretchiness or resiliency were desired (using longer aliphatic chains) or to gain higher modulus, temperature resistance and strength (with fully aromatic polymers). 

The newest commercial polymer to join the polyester family is poly(trimethylene terephthalate) (PTT) which is being targeted at fibre applications (Chapter 11). It is sold under the Corterra trademark by Shell. After packaging, the single largest use for polyesters is for fibre applications such as clothing, textiles and non-wovens. The technology of polyester fibre formation is described in Chapters 12 and 13. 

Polyethylene Terephthalate (PET) A plastic resin of the polyester family and one of the most common thermoformed plastics. Plastic soda bottle are a common PET product. PET is also fully recyclable. 

Poly(e-caprolactone) (PCL) is a biodegradable, non-toxic polymer of the polyester family suitable for implantable or injectable delivery devices (7). The degradation of PCL occurs at a very slow rate via the hydrolyzation of ester bonds, making it ideal for long term delivery systems (7). Previous studies (8-13) find that 35-55% of the initial hydrophilic drug load was released rapidly from PCL nano and micro particles, within a few hours. This burst was followed by slow release over timescales of weeks to months 8-13). 

Poly(butylene succinate) (PBS) is an important member of biodegradable aliphatic polyester family. PBS and related copolymers have shown considerable promise for uses as environmentally biodegradable thermoplastics, as well as bioabsorbable/biocompatible medical materials (/). In both cases, practical applications require that the polymer possess a high molecular weight (M >20,000) so that it can have useful mechanical properties. 

PET is a thermoplastic polymer resin of the polyester family. PET is used in synthetic fibers beverage, food and other liquid containers thermoforming applications and engineering resins often in combination with glass fiber. 

PLA is known both as poly(lactic acid) and as polylactide. It is currently the most used packaging plastic that is both biodegradable and biobased. PLA is a member of the polyester family, and is chemically synthesized from lactic acid that is derived from starch by fermentation. PLA has the following structure ... 

Many of these new plastics are in the polyester family. One that is getting attention is PEF, polyethylene furanoate. Avantium opened a PEE pilot plant in the Netherlands in 2011. PEF reportedly is similar to PET in performance, but is 100% biobased [10]. Polybutylene terephthalate (PBT) is available as a partially biobased plastic, from biobased 1,4-butanediol and petro-based terephthalic acid. Polybutylene succinate (PBS) is similarly made from biobased succinic acid and petro-based terephthalic acid. Poly(trimethylene terephthalate) (PTT) can be made from biobased 1,3-propanediol with, again, petro-based terephthalic acid. 

A variety of copolymers having high molar ratios of PDS compared to other monomers within the same linear aliphatic polyester family have been reported for the purpose of improving the mechanical and biodegradation properties [Shalaby, 1994]. For example, copolymer of PDS (80%) and PGA (up to 20%) has an absorption profile similar to Dexon and Vicryl sutures but it has compliance similar to PDS. Copolymer of PDS (85%) and PLLA (up to 15%) results in a more compliant (low modulus) suture than homopolymer PDS but with absorption profiles similar to PDS [Bezwada et al., 1990). 

Polyethylene Napthalate Polyethylene Napthalate (PEN), a new generation polymer, is a high-performance member of the polyester family. 

K2], these low-molecular-weight fragments migrate through the cell membrane and are mineralised by MOs, the degradation is called biomineralisation. From equation 1, it can be deduced that a temporary build-up of monomers can arise in case K1 K2. The biodegradable polyester family is presented in Fig. 21.9. 

Figure 21.9 The biodegradable polyester family poly(hydroxyalkanoates) (PHA), poly(hydroxybulyrate) (PHB), poly(hydro3qdiexanoate) (PHH), poly(hydrox3rvalerate] (PHV), polyflactic acid) (PLA), poly(caprolactone) fPCL), poly(butylene succinate) (PBS), poly(butylene succinate adipate) (PBSA), aliphatic-aromatic copolyesters (AAC), poly(ethylene terephthalate) (PET), poly(butylene adipate/terephthalate) (PBAT), poly(methylene adipate/terephthalate) (PTMAT). Adapted from [103].

This is a thermoplastic polymer resin of the polyester family and is usually referred to as polyester. PET can be semi-rigid to rigid depending on its thickness and is very lightweight, clear, strong and impact resistant, has good gas- and moisture-resistant barrier properties and is widely used for soft drink bottles. 

A brief introduction to commonly used polyesters would be in order here. The most well-known and daily used man-made polyester is polyethylene terephtha-late (PET)(more often written as poly(ethylene terephthalate), whose chemical structure is shown in Figure 1.3). PET is a thermoplastic polymer resin of the polyester family and is used in the form of synthetic fibers. This polyester is generally nonbiodegradable. Whinfield synthesized PET in 1941 and called it terylene [16] and Hardy [17] characterized teryleneusing a couple of methods (Figure 1.3). 

Polycyclohexylendeimethylene tere-phthalate [PCT, poly( cyclohexane-1,4-dimethylene terephthalate)] n. The newest member of the commercial thermoplastic-polyester family, PCT is produced by reacting 1,4-cyclohexane dimethanol with dimethyl terephthalate. It is superior to its siblings (PET and PBT) in that it can serve... 

Polyester, unsaturated n. A polyester family characterized by ethenic unsaturation in the polyester backbone that enables subsequent hardening or curing by co-polymerization with a reactive monomer in which the polyester constituent has been dissolved. Unsaturated polyesters are made by agitating in a heated kettle a mixture of glycols, e.g., propylene- or diethylene glycol unsaturated dibasic acids or anhydrides, e.g., fumaric acid or maleic anhydride and, sometimes in order to control the reaction and modify properties, a saturated dibasic acid, or anhydride, e.g., iosphthalic acid or phthalic anhydride. 

One of the early truly biodegradable polymers was polyhydroxybu-tyrate/valerate (PHBV). This is a member of the polyester family which is produced by certain types of bacteria when they have a diet which is carbon-rich but poor in some essential nutrient. Under these conditions, they produce polyhydroxybutyrate (PHB) as a food store to be called upon when carbon sources are less available. With manipulation of the diet, the bacteria can be induced to form a copolymer, PHBV, which has more useful properties than PHB. 

Polycaprolactone is a member of the polyester family which has been used in relatively small quantities for a long time. The most well-known supplier is Union Carbide of Danbury, Conn., which sells... 

Scanning electron images of some commercial nonabsorbable sutures (a) Silk polyester family (b) Mersilene (c) Novafil polyamide family (d) Nurolon (e) Ethilon (f) Dermalon (g) Supramid polypropylene family (h) Prolene polyvinylidene fluoride family (i) Pronova oly (ether ester) family (j) Dyloc poly(tetrafluoroethylene) family (k) Gore-Tex (I) Stainless steel. 

Bioresorbable linear aliphatic polyesters (e.g., polyglycolide, polylactide, polycaprolactone, polyhydroxybutyrate) and their copolymers within the aliphatic polyester family like poly(glycolide-L-lactide) copolymer and poly(glycolide-E-caprolactone) copolymer. 

The majority of petroleum-based compostable plastics belong to the polyester family, including Ecoflex , polycaprolactone (PCL), Ecovio , poly-butyrate adipate terephthalate (PBAT), and aliphatic copolyesters (The Impacts of Degradable Plastic Bags in Australia 2003). Table 4.14 lists several commercially available biodegradable or compostable plastic products. 

PTT is a new member in polyester family its value as a commercial polymer has improved because its monomers are not all dependent on petroleum. DuPont has successfully commercialized the production of this polymer via 1,3-propanediol obtained by fermentation and produces Polytrimethylene terephthalate (PTT) with the brand name of Sorona. The beneficial properties of Sorona are derived from a unique, semicrystalline molecular structure featuring a pronounced kink, which means that outer forces, such as tensile or compressive forces, translate at the molecular level, causing... 

For special applications, polybutylene terephthalate (PBT) is another fiber alternative in the polyester family, especially in melt blown nonwovens for filters. Properties of the typical three polyesters are shown in Table 2.26. 

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