Aromatic polyester-modified

Aromatic Polyester-Modified Foam. The formulations shown in Table 29 are examples of the co-use of an aromatic polyester and a... 

Based on the low hydrolysis degradation rate of poly(alkylene dicarboxy-late)s, it is to be expected that in vivo degradation would be a slow process. In vivo degradation investigations were mainly concentrated on aliphatic-aromatic polyesters modified by the introduction of PEO into the chain backbone. For copolyesters containing PEO, in addition to hydrolytic degradation of the ester bonds, oxidative degradation of the aliphatic ether can... 

Most polyesters (qv) are based on phthalates. They are referred to as aromatic-aHphatic or aromatic according to the copolymerized diol. Thus poly(ethylene terephthalate) [25038-59-9] (PET), poly(butyelene terephthalate) [24968-12-5] (PBT), and related polymers are termed aromatic-aHphatic polyester resins, whereas poly(bisphenol A phthalate)s are called aromatic polyester resins or polyarylates PET and PBT resins are the largest volume aromatic-aHphatic products. Other aromatic-aHphatic polyesters (65) include Eastman Kodak s Kodar resin, which is a PET resin modified with isophthalate and dimethylolcyclohexane. Polyarylate resins are lower volume specialty resins for high temperature (HDT) end uses (see HeaT-RESISTANT POLYAffiRS). 

Groupe TBI is investing about FFr3m to build a 15,0001/ y aromatic polyester polyols plant on a greenfield site at Issoire, near Lyons. The novel, patented process uses postconsumer waste bottles made from PETP as feedstock. PU and modified PIR foams made using the APPs have excellent fire performance and good dimensional stability. GROUPE TBI... 

The solution is a combination of aliphatic polyesters and aromatic polyesters. This involves modifying the crystalline structure of PBT by incorporating aliphatic monomer (adipic acid) in the polymer chain in such a way that the material properties of the polymer would remain acceptable (e.g., melting point of the crystalline range still around 100 °C), but the polymer would also be readily compostable/biodegradable. In this way it was possible to combine the degradability of aliphatic polyesters with the outstanding properties of aromatic polyesters. 

Copolymerization can be employed in a similar fashion to modify the properties of the homopolymer of /7-hydroxybenzoic add (5-6). Poly(/ -hydroxybenzoic acid) is an infusible polymer which can be shaped only by compression sintering. A melt processable variation of this high modulus, thermally stable material can be made, however, by copolymerizing an ester of 5-6 with equimolar quantities of terephthalic acid (5-7) and biphenol (5-8) to produce an aromatic polyester which can be fabricated at temperatures near400 C but still retain many useful properties at 300°C. 

The polyols which function as modifiers include ethylene glycols, 1,4-butanediol, polyether polyols and polyester polyols. In recent years aromatic polyesters prepared from reclaimed PET (polytetraethylene terephthalate) or the distillation residue of DMT (dimethylterephthalate) have appeared as modifiers for urethane-modified isocyanurate foams (73, 78). These aromatic polyesters are produced by the transesterification of reclaimed PET or DMT distillation residue. 

Although studies concerning main chain liquid crystalline polymers were originated by Onsager (la) and Ishihara (lb) in the late 1940 s, extensive work in this field did not really begin until the early 1970 s. Jackson and Kuhfuss (2) reported the first thermotropic polyester by modifying polyethylene terephthalate with various amounts of p-hydroxybenzoic acid (HBA). They found that the copolyester with HBA content of at least 35 mole % have opaque melts. Subsequent studies in the area of aromatic polyesters by various authors resulted in a large number of patents and publication. (3.) These polymers were all derived from unsubstituted and... 

Figure 9.4 and Table 9.1 respectively show the chemical structure and the properties of these materials. Most commonly used is poly(butylene adipate-co-terephtalate) (PBAT). BASF, DuPont and Zhejiang Hangzhou Xinfu (China) manufacture and market these aromatic polyesters, under the respective brands Ecoflex , Biomax and Biocosafe . Biomax has a high terephthalic acid content, which modifies some of its properties such as the melting temperature (200°C). According to Muller et al., an increase in terephthalic acid content tends to decrease the rate of biodegradation into compost [MUL 97]. 

As flexible substituents, linear and branched alkyl, alkoxy, or thioalkyl side chains of different lengths have been utilized to modify para-linked aromatic polyesters. The main difference to the systems discussed above is the limited thermal stability caused by the substitution with alkyl chains. Also, the mechanical poperties are substantially lowered with increasing... 

Thermotropic liquid crystalline polyesters can be prepared by the use of meta-oriented modifiers to reduce the melting points of para-substituted aromatic polyesters to the processible range. Resorcinol, isophthalic acid and m-hydroxybenzoic acid are commonly used. Figure 14 shows the effect of copolymerized m-hydroxybenzoic acid on the physical properties of melt processable, modified polyesters based on terephthalic acid and methylhydro-quinone. As the m-hydroxybenzoic acid (MHB) content increases... 

Kou et al., reported using a hyperbranched acrylated aromatic polyester as a modifier in UV eurable epoxyacrylate resin. The material is compatible with the epoxy-acrylate resins. They found that the photopolymerization rate of the resin is promoted by this modifier. Also, the shrinkage of the resin was redueed. At the same time, the tensile, flexmal, compressive strength, and thermal properties of the ultraviolet light eured films are greatly improved. 

Polyurethane-modified polyisocyanurate (PIR) foams have a reputation for being the most flame resistant of the PU related foams used for insulation. They are increasingly being made from an aromatic polyester polyol (APP) and the isocyanate is most often MDI. Unlike pol5mrethanes, however, the amount of MDI is comparatively high. Isoeyanate indices of 250 or higher are used... 

Based on this work on aromatic polyesters, Schnell et al. [30] and Fox [31] independently prepared hnear, bigh-melting, bigh-molecular-weight aromatic polycarbonates in 1953—1954 that were derived from 4,4 -dihydroxy-diphenylalkane monomers. These aromatic polycarbonates could be prepared either (1) by a two-phase interfacial method (a modified Schotten-Baumann reaction) or (2) by a melt transesterification (monomers-as-solvent) process using diphenyl carbonate [32]. Versus earher aUphatic polycarbonates, the aromatic polycarbonates were unique in tbat they could be made into water-clear (colorless) transparent structures tbat possessed excellent long-term mechanical properties. 

The history of thermoplastic polyester goes back to 1929 with the pioneering work of Carothers. The first aromatic polyester of importance is poly(ethylene terephthalate) commonly abbreviated PET (or PETE) and was prepared by Whinfield and Dickson. In 1941, they created the first polyester fibers called Terylene and first manufactured by Imperial Chemical Industries (ICI). PET was produced commercially in 1953 as fiber for textile industry (Dacron) by Dupont using modified nylon technology. Dupont polyester research rapidly leads to a whole range of trademarked products as Mylar, a strong polyester film. 

The introduction of aliphatic add residues into polyfether ester)s chain allows the attractive combination of the advantages of aromatic polyesters, such as excellent mechanical properties and thermal stabilities and the biodegradability and solubility of aliphatic residues [86,87]. Also, the incorporation of different type of ether soft segments into aromatic polyesters could modify or enhance their degradability [88]. 

The biodegradable materials obtainable from starch modified with aliphatic or aliphatic/aromatic polyesters, discussed in Section 6.1.6, proved to be particularly suitable for the production of shopping bags and are today leading this sector. 

Among biodegradable polyesters, we distinguish between aliphatic polyesters and modified aromatic polyesters [950] ... 

In contrast to most aliphatic polyesters, aromatic polyesters like PET provide excellent material properties [50]. To combine good material properties with biodegradability, aliphatic/aromatic copolyesters have been developed. Several major polyester producers in Europe and the United States have recently begun marketing aliphatic/aromatic copolyesters for biodegradable applications. BASF markets a product, Ecoflex , which is a copolyester of butanediol, adipic acid, and dimethyl terephthalate. Eastman s Eastar Bio Copolyester 14766 is a similar aliphatic/aromatic copolyester. DuPont markets a modified PET known as Biomax . 

---