1,4-butanediol process improvement

Statistical copolymerization of ethylene glycol and 1,4-butanediol with dimethyl ter-ephthalate results in products with improved crystallization and processing rates compared to poly(ethylene terephthalate). Polyarylates (trade names Ardel, Arylon, Durel), copolymers of bisphenol A with iso- and terephthalate units, combine the toughness, clarity, and proce-sibility of polycarbonate with the chemical and heat resistance of poly(ethylene terephthalate). The homopolymer containing only terephthalate units is crystalline, insoluble, sometimes infusible, and difficult to process. The more useful copolymers, containing both tere- and isophthalate units, are amorphous, clear, and easy to process. Polyarylates are used in automotive and appliance hardware and printed-circuit boards. Similar considerations in the copolymerization of iso- and terephthalates with 1,4-cyclohexanedimethanol or hexa-methylene diamine yield clear, amorphous, easy-to-process copolyesters or copolyamides,... 

Another useful class of reactions which has been successfiilly demonstrated as a continuous SCF process are etherfication/cyclisation reactions, again using acid catalysts [52]. Examples include the formation of asymmetric esters and heterocyclic compounds. Scheme 12.2 shows the intramolecular cyclization of 1,4-butanediol over Amberlyst-15 at 120 bar, 170 °C, which produces the heterocyclic compound tetrahydrofuran (THE). 1,4-Butanediol has a melting point of 16 °C, and so, although not strictly required, a small amount of methanol may be added to the reactants to aid solubility during decompression of the SCF. Adding a cosolvent to the system may also improve solubility in SCCO2 [13]. 

Poly- -caprolactone (PCL) and its copolymers polyesters of 1,4-butanediol with succinic, sebacic, adipic, azelaic, decanoic or brassihc acids. Thermoplastic starch (Mater-Bi). Blends improved processability biodegradabUity. Compatibihzation by amylose/EVAl complexes, starch grafted polyesters, chain extenders like diisocyanates, epoxies, etc. Bastioli et a/., 1992, 1993... 

Solution polymerization of succinic acid and butanediol to PBS. Solution polymerization is a modified method of direct melt polymerization, which dissolves the raw materials in a solvent such as xylene or decahydronaphlhalene. The esterification reaction and the condensation reaction in the solvent improve the removal of the small molecular material formed in the reaction process, so the reaction can be conducted at lower temperature, which can avoid oxidation of PBS, but at the cost of a longer reaction time. 

Cheng KK, Liu Q, Zhang JA, Li JP, Xu JM, Wang GH. (2010). Improved 2,3-butanediol production from corncob acid hydrolysate by fed-batch fermentation using Klebsiella oxytoca. Process Biochem, 45, 613-616. 

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. 

PBS, is an APES with good biodegradability, melt processability, and thermal and chemical resistance. It is generally synthesized by polycondensation of 1,4-butanediol with succinic acid. Thanks to the successfiil incorporation of nanoparticles into other polyesters resulting in remarkable improvements of properties, this technique also has been introduced into PBS systems [144]. Ray et al. [325, 326] studied the structure and properties of PBS based with OMMT with a... 

Blends of biodegradable synthetic aUphatic polyesters and starch are used to produce sheets and films for packaging by film extmsion or blown film methods. Up to 50% of the synthetic polyester can be replaced with starch. A polyester synthesised from the poly-condensation of 1,4-butanediol and a mixture of adipic and succinic acids has been blended with wheat starch by Lim (1999) (Nolan-ITU Pty Ltd, 2002). The blends were found to have melting points near that of the polyester alone. Plasticisers were also added to the starch to improve flexibiUty and processability of the blend. The modified blends were found to retain a high tensile strength and elongation, even at high starch concentrations. 

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