Polyester–polycarbonate blends. V. Linear aliphatic polyesters

Polycarbonate blends with the linear aliphatic polyesters poly(ethylene succinate) (PES), poly(ethylene adipate) (PEA), poly(1,4-butylene adipate) (PBA), and poly(hexamethylene sebacate) (PHS) were prepared by solution casting. Blends containing PES, PEA, and PBA exhibited a single T_g by DSC and thus form a single, miscible amorphous phase with polycarbonate. However, blends containing PHS exhibited only partial miscibility. Crystallinity of the polyesters was reduced by mixing with polycarbonate; however, plasticization by the polyesters induced crystallization of the polycarbonate. Miscibility in these systems is the result of an exothermic heat of mixing stemming from an interaction of the carbonyl dipole of the ester group with the aromatic carbonate. The effect of polyester structure on miscibility with polycarbonate is interpreted by and correlated with heats of mixing obtained by direct calorimetry of low molecular weight liquid analogs of the polymers.     

Radiation‐induced crosslinking of acetylene‐impregnated polyesters. II. Effects of preirradiation crystallinity,molecular structure,and postirradiation crosslinking on mechanical properties

Electron beam‐irradiated crosslinking has been studied in a series of acetylene‐impregnated polyesters and amorphous copolyesters, including poly(ethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(cyclohexane dimethylene terephthalate) (PCDT), and poly(cyclohexane dimethylene terephthalate‐co‐ethylene terephthalate) (P(CDT‐co‐ET)) having 29 and 60 wt % ethylene terephthalate (ET). The extent of crosslinking was observed by gel fraction measurements and was found to be significantly influenced by the aliphatic chain content of the polyesters (PET < PBT < PCDT). In addition, as the preirradiation crystallinity of the polyesters was reduced, the extent of acetylene‐enhanced crosslinking was greatly raised. Decreases in the postirradiation crystalline melting temperature and degree of crystallinity were observed in all the polyesters, using differential scanning calorimetry measurements. Particularly significant findings have been the shift in the glass‐transition temperatures (Tg) to higher temperatures and the decrease in loss tangents at higher temperatures, both of which confirm that crosslinking has taken place. The storage moduli (E′) in the rubbery plateau region of PCDT and P(CDT‐co‐ET) were significantly affected by irradiation dose. Increased network tightness in postirradiated PBT and PCDT films was also inferred from melt‐rheology measurements, in which stress relaxed more slowly following a stepped strain. Improvements in the mechanical properties of the irradiated polyesters and copolyesters were clearly evidenced by the increased modulus at higher temperatures, observed using dynamic mechanical thermal analysis and melt‐rheology methods. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4476–4490, 2006     

A review on the potential biodegradability of poly(ethylene terephthalate)

This paper reviews the state of the art in the field of the hydrolytic degradation of poly(ethylene terephthalate) (PET) under bio-environmental conditions. Most of the papers published so far on this subject have been focused on the hydrolysis of PET at high temperatures. Although some authors claim to enhance the biodegradation properties of this aromatic polyester by copolymerization with readily hydrolysable aliphatic polyesters, no clear and satisfying conclusions can yet be formulated. Poly(ethylene terephthalate-co-lactic acid), poly(ethylene terephthalate-co-ethylene glycol), and poly(ethylene terephthalate-co-ε-caprolactone) block and random copolymers are the modifications mainly investigated for biodegradable applications. The hydrodegradability and biodegradability of PET, PET copolymers and PET blends are detailed in this review. A total of 89 references including 16 patents are cited. © 1999 Society of Chemical Industry     

Correlation between interactions, miscibility, and spherulite growth in crystalline/crystalline blends of poly(ethylene oxide) and polyesters

Crystalline/crystalline blend systems of poly(ethylene oxide) (PEO) and a homologous series of polyesters, from poly(ethylene adipate) to poly(hexamethylene sebacate), of different CH₂/CO ratios (from 3.0 to 7.0) were examined. Correlation between interactions, miscibility, and spherulite growth rate was discussed. Owing to proximity of blend constituents' T_g's, the miscibility in the crystalline/crystalline blends was mainly justified by thermodynamic and kinetic evidence extracted from characterization of the PEO crystals grown from mixtures of PEO and polyesters at melt state. By overcoming experimental difficulty in assessing the phase behavior of two crystalline polymers with closely spaced T_g's, this work has further extended the range of polyesters that can be miscible with PEO. The interaction parameters (χ₁₂) for miscible blends of PEO with polyesters [poly(ethylene adipate), poly(propylene adipate), poly(butylene adipate), and poly(ethylene azelate) with CH₂/CO = 3.0-4.5] are all negative but the values vary with the polyester structures, with a maximum for the blend of PEO/poly(propylene adipate) (CH₂/CO = 3.5). The values of interactions are apparently dependent on the structures of the polyester constituent in the blends; interaction strength for the miscible PEO/polyester systems correlate in the same trend with the PEO crystal growth rates in the blends.     

缩聚法合成生物可降解聚酯研究进展

本文从分子设计的角度,综述了缩聚法合成生物可降解聚酯的研究进展,涉及脂肪族聚酯和含有芳香组分聚酯的合成。其中,对脂肪族聚酯 聚乳酸的缩聚合成,以及可再生资源用于聚酯的合成进行了重点介绍。同时也对一些合成聚酯的生物降解性能与结构的关系进行了讨论。     

Hydrolysis of copolyesters containing aromatic and aliphatic ester blocks by lipase

Copolyesters (CPEs) prepared by the transesterification reaction between aromatic and aliphatic polyesters were hydrolyzed by Rhizopus delemar lipase. The susceptibility of CPEs to hydrolysis by this lipase dropped off rapidly during the initial stage of the transesterification reaction and increased gradually as the reaction proceeded. The susceptibility to hydrolysis decreased with increase in aromatic polyester content. It was concluded that the rigidity of the aromatic ring in the CPE chains strongly influenced their susceptibility to hydrolysis by this lipase.     

Synthesis and characterization of high‐molecular weight aliphatic polyesters from monomers derived from renewable resources

A series of high‐molecular weight aliphatic polyesters have been synthesized, at temperatures of < 200°C, through a polycondensation reaction between 1,4‐butanediol and three diacids of different chain length (succinic acid, azelaic acid, and sebacic acid). All the polyesters obtained have a bio‐based content of 100% and number average molecular weight in the range of 28,000–116,000 Da. These average molecular weights are about 5–10 times higher than those of most reported aliphatic polyesters synthesized through similar reaction routes but at temperatures > 230°C. The over‐heating phenomenon, i.e., the observation of thermal degradation behavior of these polyesters at 230°C is reported. The crystallization behavior, mechanical properties, and enzymatic hydrolysis rate of the polyesters obtained are characterized. Poly(butylene succinate) (PBSu) shows the highest crystallinity and melting temperature, but the lowest thermal stability and slowest potential rate of enzymatic biodegradation rate compared with poly(butylene azelate) and poly(butylene sebacate). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40579.     

Functional modification of biodegradable polyesters through a chemoselective approach: application to biomaterial surfaces

This paper presents an overview of functional modifications of synthetic aliphatic polyesters and a new synthetic route to graft functional moieties onto the polyester backbone by a chemoselective approach. Aminooxy groups react efficiently and selectively with ketones or aldehydes to form oxime linkages under mild reaction conditions without catalysts, even in the presence of other functional groups. Chemoselective coupling of aminooxy‐terminated poly(ethylene oxide) (PEO) onto ketone‐bearing poly(ε‐caprolactone) (PCL) was exploited to prepare comb‐shaped copolymers that exhibit cell resistance when the PEO content is above 30 wt%. The free hydroxyl groups of PEO chain ends allowed further incorporation of cell signaling peptides including the sequence RGD. The results show chemoselective coupling to be a promising general route for introducing functional pendant groups onto most polyesters obtained by ring‐opening polymerization without backbone degradation. Copyright © 2006 Society of Chemical Industry     

Synthesis,characterization, and stability of poly[(alkylene oxide) ester] thermoplastic elastomers

Poly(ether ester) block copolymers were prepared using a transesterification/polycondensation bulk synthesis with systematic control of the terephthalic acid/butane-diol aromatic diester block (`hard segment') and with poly(tetramethylene oxide) [PTMO], poly(hexamethylene oxide) [PHMO], or poly(decamethylene oxide) [PDMO] poly(alkylene oxide) soft segments. The respective number average molecular weights were 980, 930, and 940 Da. A series of the poly(ether ester)s with hard segment fractions of 25, 29, 37, and 51% were prepared. One example of the PDMO polyester was prepared at a 51% hard segment fraction. The polyesters were characterized using viscometry, gel permeation chromatography, ¹H-NMR spectroscopy, differential scanning calorimetry, and tensile testing. The novel poly(ether ester)s, the PTMO polyester, and the commercial control, Hytrel® 4056, were compared for their resistance to degradation in a 50% aqueous hydrogen peroxide solution at 37°C, boiling water buffered at pH 1 and 13, an oxygen stream at 200°C, and a nitrogen stream at 200°C. The Hytrel® 4056 and the PTMO polyesters fragmented in hydrogen peroxide within 24 h while the PHMO and PDMO polyesters were much less degraded. Resistance to hydrolytic and thermal degradation increased as the ratio of aliphatic methylene to ether increased: PTMO < PHMO < PDMO. Samples containing higher hard segment fractions demonstrated improved resistance to hydrolysis. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1319–1332, 1997     

Blends of thermoplastic polyesters with amorphous polyamide. I. Thermal and crystallization behavior

The thermal and crystallization behavior of blends of three thermoplastic polyesters with different degrees of crystallizability, with an amorphous aromatic polyamide is reported. The thermoplastic polyesters used in the investigation were poly(butylene terephthalate) (PBT), poly(ethylene terephthalate) (PET) and a co-polyester of 1,4 cyclohexane-dimethanol, ethylene glydol and terephthalic acid (PETG). The blends exhibited a single glass transition temperature indicating mlseibility in the amorphous phase. The results of thermal analysis indicated that the crystallization of all the three polyesters is facilitated in the molten phase as a result of blending. The blending significantly Increased the degree of crystallinity of PET, but there was no change in the crystallinity of PBT. It is thus observed that the extent of change in both the crystallization rate and the degree of crystallinity of polyesters depend on the inherent crystallizability of the individual polyester.     

Unsaturated polyester based on poly(ethylene glycol)

Unsaturated polyesters were prepared by one-stage melt condensation of maleic anhydride, phthalic anhydride, propylene glycol, and poly(ethylene glycol)s with different molecular weight, and the properties of their castings from styrenated resins were investigated. Tensile and flexural properties decrease with the increase of molecular weight of poly(ethylene glycol), but impact strength, elongation, and water absorption have an inverse effect. This study improves the understanding of the effect of chain length of poly(ethylene glycol) in unsaturated polyester on the properties of its castings.     

Syntheses and properties of the PET‐co‐PEA copolyester

An aliphatic‐aromatic random‐block copolyester of poly(ethylene terephthalate) (PET), and poly(enthylene adipate) (PEA), PET‐co‐PEA, was synthesized via melt polycondensation. The chemical structure of the products were characterized by two kinds of spectroscopic techniques (Fourier transform infrared and ¹H‐NMR). The thermal properties of the copolyester were characterized by thermogravimetry analysis, differential scanning calorimetry, wide‐angle X‐ray diffraction, and polarized optical microscopy. It was found that the crystallization ability, melting point, glass transition temperature of the random‐block coplyester decreased apparently. Meanwhile, the tensile strength and hydrolysis performance were measured as well. The result showed that the random‐block copolyesters PET‐co‐PEA displayed excellent properties in elasticity and strength. In addition, the potential degradability was found in hydrolysis measurement. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44967.     

Preparation and characterization of water‐extended polyester based on recycled poly(ethylene terephthalate)

An unsaturated polyester resin was prepared that was based on the reaction of oligomers obtained from the depolymerization of poly(ethylene terephthalate) waste products, with both maleic anhydride and sebacic acid. The structure of the produced polyester was compared with that prepared from the reaction of dimethyl terephthalate with both maleic anhydride and sebacic acid with IR and NMR spectroscopy. Water‐extended polyester resins were prepared from these two polyesters through curing with styrene in the presence of various amounts of water with benzoyl peroxide as an initiator. The mechanical properties of the prepared water‐extended polyesters, as well as scanning electron microscopy, were investigated. The use of water‐extended polyesters based on recycled poly(ethylene terephthalate) waste for the preparation of decorative art objects and statues was investigated. Therefore, three pharaonic statues representing Tutankhamen, Nefertiti, and a black head of a cat were prepared. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3693–3699, 2003     

Comparison of aliphatic polyesters prepared by acyclic diene metathesis and thiol-ene polymerization of α,ω-polyenes arising from oleic acid-based 9-decen-1-ol

Development of more sustainable and environmentally friendly polymers as alternatives to petroleum-based polymers is a priority. We report the synthesis of six linear, aliphatic, renewable polymers by acyclic diene metathesis (ADMET) and thiol-ene polymerization of α,ω-polyenes resulting from thermal esterification of adipic, azelaic, and itaconic acids with 9-decen-1-ol. ADMET homopolymerization was performed with 1.0 mol% Hoveyda–Grubbs second generation metathesis catalyst. Thiol-ene copolymerization was conducted photochemically with 1 wt% 2,2-dimethoxy-2-phenyl-acetophenone and stoichiometric 1,2-ethanedithiol (EDT). Although the thiol-ene copolymers exhibited carbon and atom economies of 100%, the ADMET-derived polyesters possessed superior renewable carbon content (100%) and environmental factors (<4). These results were attributed to incorporation of non-renewable EDT into poly(thioether-ester)s and loss of ethene during production of ADMET polyesters. The M_n (>26 kDa), M_w (>92 kDa), and dispersities (>3.4) of the poly(thioether-ester)s were higher than the corresponding polyesters, which in part explained why the poly(thioether-ester)s gave higher melting (>61°C), crystallization (>49°C) and glass transition (>−31°C) temperatures. The cross-linked itaconate polymers did not melt or crystallize, thereby suggesting amorphous morphology. Lastly, the ADMET polyesters were more thermally stable (T₅₀ > 408°C) than the poly(thioether-ester)s (T₅₀ < 377°C). In summary, the aliphatic biopolymers displayed a wide range of properties that were impacted by polymerization method as well as the nature of the monomer.     

Synthesis and characterization of a novel unsaturated polyester based on poly(trimethylene terephthalate)

Unsaturated aromatic polyesters were obtained by glycolysis of poly(trimethylene terephthalate) with cis-2-buten-1,4-diol followed by a solid-state polymerization. The glycolysis was performed in a batch mode as well as through a continuous process in a twin screw extruder. The degradation and subsequent rebuilding of the polymer chain during the course of reaction was followed by means of inherent and melt viscosity measurements, and ¹H NMR terminal group analysis of the intermediates and the final products. Structural investigations revealed that this new approach resulted in melt processible unsaturated polyesters with cross-linkable sites having similar characteristics to that of the virgin saturated polyester. Although the processing temperature for the different reaction steps was sufficiently high (180−260 °C), no thermally induced cross-linking of the incorporated unsaturated bonds could be evidenced indicating that the obtained products remained stable during the production stage. For comparison purposes, a commercial unsaturated polyester (Vestodur^©) was included in the investigations. UV irradiation of thin polyester films did not result in cross-linked products but in cis-trans isomerization of the incorporated bisoxybutenyl unit.     

Biodegradable polymers based on renewable resources. IV. Enzymatic degradation of polyesters composed of 1,4:3.6‐dianhydro‐D‐glucitol and aliphatic dicarboxylic acid moieties

Enzymatic degradation of a series of polyesters prepared from 1,4:3.6‐dianhydro‐D ‐glucitol (1) and aliphatic dicarboxylic acids of the methylene chain length ranging from 2 to 10 were examined using seven different enzymes. Enzymatic degradability of these polyesters as estimated by water‐soluble total organic carbon (TOC) measurement is dependent on the methylene chain length (m) of the dicarboxylic acid component for most of the enzymes examined. The most remarkable substrate specificity was observed for Rhizopus delemar lipase, which degraded polyester derived from 1 and suberic acid (m = 6) most readily. In contrast, degradation by Porcine liver esterase was nearly independent of the structure of the polyesters. Enzymatic degradability of the polyesters based on three isomeric 1,4:3.6‐dianhydrohexitols and sebacic acid was found to decrease in the order of 1, 1,4:3.6‐dianhydro‐D ‐mannitol (2), and 1,4:3.6‐dianhydro‐L ‐iditol (3). Structural analysis of water‐soluble degradation products formed during the enzymatic hydrolysis of polyester 5g derived from 1 and sebacic acid has shown that the preferential ester cleavage occurs at the O(5) position of 1,4:3.6‐dianhydro‐D ‐glucitol moiety in the polymer chain by enzymes including Porcine pancreas lipase, Rhizopus delemar lipase, and Pseudomonas sp. lipase. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 338–346, 2000     

Preparation and properties of water‐soluble polyester surfactants. II. Preparation and surface activity of silicone‐modified polyester surfactants

We prepared a novel series of water‐soluble silicone‐modified polyesters [poly(ethylene glycol) (PEG)–silicone polyesters] by reacting organopolysiloxane with a hydroxy‐terminated polyester. The polyesters were obtained by the polymerization of maleic anhydride and PEGs (molecular weights = 2000, 4000, 6000, 8000, and 10000). These water‐soluble PEG–silicone polyesters can be used as auxiliaries in dyeing process because they exhibit good surface activities such as surface tension, low foaming, and wetting power. The presence of these surfactants also retarded the rate of nylon dyeing with acid dyes. The retarding effect and low‐foaming property of these novel PEG–silicone polyesters make it possible for these surfactants to be used as leveling agents for modern nylon dyeing with acid dyes. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3005–3012, 2002     

生物降解性脂肪族聚酯改性的研究进展

综述了脂肪族聚酯改性制备生物降解性聚酯的研究进展.在聚酯中引入刚性链段(即将脂肪族聚酯与芳香族、液晶基元共聚合)可改善聚酯的加工性能;在聚酯中引入亲水基大分子(即将脂肪族聚酯淀粉共混或与聚乙二醇共聚合)可改善聚酯的亲水性能.今后脂肪族聚酯改性研究的重点将解决功能化基团的引入、合成路线的简化、成本的降低及改性的效果等方面的问题.     

Modification of bismaleimide resin by poly(ethylene phthalate‐co‐ethylene terephthalate), poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate), and poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)

Aromatic polyesters were prepared and used to improve the brittleness of bismaleimide resin, composed of 4,4′‐bismaleimidodiphenyl methane and o,o′‐diallyl bisphenol A (Matrimid 5292 A/B resin). The aromatic polyesters included PEPT [poly(ethylene phthalate‐co‐ethylene terephthalate)], with 50 mol % of terephthalate, PEPB [poly(ethylene phthalate‐co‐ethylene 4,4′‐biphenyl dicarboxylate)], with 50 mol % of 4,4′‐biphenyl dicarboxylate, and PEPN [poly(ethylene phthalate‐co‐ethylene 2,6‐naphthalene dicarboxylate)], with 50 mol % 2,6‐naphthalene dicarboxylate unit. The polyesters were effective modifiers for improving the brittleness of the bismaleimide resin. For example, inclusion of 15 wt % PEPT (MW = 9300) led to a 75% increase in fracture toughness, with retention in flexural properties and a slight loss of the glass‐transition temperature, compared with the mechanical and thermal properties of the unmodified cured bismaleimide resin. Microstructures of the modified resins were examined by scanning electron microscopy and dynamic viscoelastic analysis. The toughening mechanism was assessed as it related to the morphological and dynamic viscoelastic behaviors of the modified bismaleimide resin system. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2352–2367, 2001     

Synthesis and physical properties of lipid-based poly(ester-urethane)s,I: Effect of varying polyester segment length

Four aliphatic thermoplastic poly(ester-urethane)s (PEUs) with similar molecular weights but varying polyesters molecular weight (534–1488 g/mol) were prepared from polyester diols, obtained by melt condensation of Azelaic acid and 1,9-Nonanediol, and 1,7-heptamethylene di-isocyanate (HPMDI) all sourced from vegetable oil feedstock. The thermal, and mechanical properties, and crystal structure of PEUs were investigated using DSC, TGA, DMA, tensile analysis and WAXD. For sufficiently long polyester chain, WAXD data indicated no hydrogen bonds polyethylene (PE)-like crystalline packing and for short polyester chains, small crystal domains with significant H-bonded polyamide (PA)-like packing. Crystallinity decreased with decreasing polyester molecular weights. The polymorphism of PEUs and consequently their melting characteristics were found to be largely controlled by polyester segment length. TGA of the PEUs indicated improved thermal stability with decreasing polyester chain length, suggesting a stabilization effect by urethane groups. Mechanical properties investigated by DMA and tensile analysis were found to scale predictably with the overall crystallinity of PEUs.