Influence of water on the photodegradation of poly(ethylene oxide)

The UV-light degradation of polyethylene oxide (PEO) in aqueous solution was investigated operating under long wavelengths (λ > 300 nm) at 20 °C in different pH conditions varying from 2.3 to 12.0 and at two different concentrations. Thermo-oxidation experiments on PEO aqueous solution at 50 °C are also reported and compared to photo-oxidation results. The formation of oxidation products was followed by infrared analysis of deposits obtained by evaporation of aliquots of irradiated polymer solution. Photo-oxidation led to formates and esters but a third product was also identified, formic acid ions formed by partial hydrolysis of formates. The degradation of PEO in water led to the acidification of the aquatic medium. Size exclusion chromatography (SEC) was used to monitor the changes in molar weight and intrinsic viscosity with irradiation time. It was shown that the photo-oxidation produced a dramatic decrease of the average molar weights which is more important in acidic medium. Total organic carbon (TOC) measurements of the aged aqueous solutions showed that the mineralization of PEO could not be achieved in these photo-oxidative conditions.     

Anti-biofouling by degradation of polymers

Copolymers of methyl methacrylate (MMA) and acrylate terminated poly(ethylene oxide-co-ethylene carbonate)(PEOC) macromonomer (PEOCA) were synthesized,and the degradation of the polymers was investigated by use of quartz crystal microbalance with dissipation (QCM-D).It is shown that the polymeric su     

Formulation selection of aliphatic aromatic biodegradable polyester film exposed to UV/solar radiation

Aliphatic aromatic copolyester films, poly(butylene adipate-co-terephthalate) or PBAT, are susceptible to photodegradation, leading to main chain scission and crosslinking. The presence of crosslinked structures not only decreased the mechanical properties of the film due to embrittlement, but also hindered the biodegradation process by limiting access of water and microorganisms to the polymer chains. This has limited the use of PBAT for outdoor applications, such as mulch films. In this study, response surface methodology (RSM) was used to determine the optimal concentrations of carbon black (CB) and the chain breaking antioxidant butylated hydroxytoluene (BHT) for the design of mulch films that can prevent the formation of crosslinked structures from recombination of free radicals. An overlaid contour plot of suitable concentrations of CB and BHT for the formulation of mulch film for crop production in Michigan or regions with similar solar radiation was established using selection criteria of light transmission of less than 20%, final tensile strength of at least 6.35 MPa, maximum gel fraction of 0.30, and positive number average molecular weight reduction sensitivity in the early stage of degradation.     

Structure,rheology and electrospinning of zein and poly(ethylene oxide) in aqueous ethanol solutions

This study provided a clear correlation of the structure and rheology of solutions with the morphologies of EFM made up of proteins and polymers.     

Photodegradation studies of novel biodegradable blends based on poly(ethylene oxide) and pectin

Blends of two biodegradable polymers: natural pectin and synthetic poly(ethylene oxide) at different weight-ratios were obtained by physical mixing in aqueous solutions, and evaporation of the solvent. The macromolecular order in the composites was investigated by applying X-ray diffraction, while the surface morphology was observed using atomic force microscopy. The photooxidative degradation of the blends was studied by viscometry, FTIR spectroscopy and UV-vis spectroscopy. It has been found that the susceptibility of the studied composites to UV radiation depends on an appropriate ratio of components, and the most sensitive to UV-irradiation among the samples studied was the equal weight-ratio blend of poly(ethylene oxide)/pectin.     

Photodegradation Behavior of Polycaprolactone-Poly(ethylene glycol) Block Copolymer

Polycaprolactone-poly(ethyleneglycol)(PCE)blockcopolymerisabiodegradablepolymer.ThebiodegradationcharacterisationinvitFoandinvivoofthePCEwasreported"'.ItwasfoundthatthedegradationrateofthePCEwasincreasedwithincreasingpoly(ethyleneglycol)content,temperature,acidityandalkalinityanditwasacceleratedbythepresenceofenzyme.Thefastestdegradationratewasobservedinthephysiologicalconditionofthesamplebeingimplantedinthebodyofanimals.SoPCEcopolymerpossessesagoodprospecttobebio-medicalmaterials3.Mostp…     

Swelling of poly(ethylene oxide) gel in aqueous solutions of sodium dodecyl sulfate with added sodium chloride

The swelling behavior of poly(ethylene oxide) (PEO) gels in aqueous solutions of sodium dodecyl sulfate (SDS) with and without NaCl was investigated. In the absence of NaCl, PEO gels with different degrees of cross-linking began to swell from a concentration lower than the critical micelle concentration (cmc) of SDS, then showed sigmoidal enhancements of swelling in a higher SDS concentration region until the degrees of swelling reached maximum values. The SDS concentration at which the swelling began to appear was in reasonable agreement with the critical aggregation concentration (cac) value reported for the aqueous PEO system. For the cases where NaCl was present, the swelling behavior of PEO gel was different from that when NaCl was absent in the following way. The concentrations where the swelling begins to appear, and hence those where the degree of swelling rises steeply, decreased with an increase in NaCl concentration. The ultimate degrees of swelling at higher concentration regions also decreased with an increase in the NaCl concentration. The lowering of the SDS concentrations at which the PEO gel began to swell is in line with the decreases in the cmc of SDS solutions containing NaCl and also with the decreases in the cac of PEO solution. Electronic Publication     

Effect of temperature on the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions

In this work the intrinsic viscosity of poly(ethylene glycol)/poly(vinyl pyrrolidone) blends in aqueous solutions were measured at 283.1–313.1 K. The expansion factor of polymer chain was calculated by use of the intrinsic viscosities data. The thermodynamic parameters of polymer solution (the entropy of dilution parameter, the heat of dilution parameter, theta temperature, polymer–solvent interaction parameter and second osmotic virial coefficient) were evaluated by temperature dependence of polymer chain expansion factor. The obtained thermodynamic parameters indicate that quality of water was decreased for solutions of poly(ethylene oxide), poly(vinyl pyrrolidone) and poly(ethylene oxide)/poly(vinyl pyrrolidone) blends by increasing temperature. Compatibility of poly(ethylene oxide)/poly(vinyl pyrrolidone) blends were explained in terms of difference between experimental and ideal intrinsic viscosity and solvent–polymer interaction parameter. The results indicate that the poly(ethylene glycol)/poly(vinyl pyrrolidone) blends were incompatible.     

Preparation of degradable polypropylene by an addition of poly(ethylene oxide) microcapsule containing TiO2

In order to prepare a novel photo-degradable polypropylene (PP), an addition of poly(ethylene oxide) (PEO) microcapsule containing TiO₂ to PP was performed. Adsorbed H₂O in the PEO phase and the TiO₂ photocatalytically reacted, and a hydroxyl radical (OH), which initiated the PEO degradation, was produced. The degraded PEO produced an acid and an aldehyde, which were able to facilitate PP degradation. The addition of the PEO/TiO₂ microcapsule brought about the facilitative effect of the PP degradation. In addition, an addition of a hindered amine light stabilizer (HALS) had a potential to suppress the PP degradation initiated by the microcapsule. The suppression effect was rising by the simultaneous addition of a phenolic antioxidant in the early phase of the PP degradation. However, the simultaneous addition showed an antagonism after 4 h degradation. This behavior suggested that the HALS also worked as a neutralizer of the produced acid.     

Phase diagram and thermodynamic modeling of PEO + organic salts + H2O and PPO + organic salts + H2O aqueous two-phase systems

The phase diagrams of PEO1500 + sodium tartrate + water, PPO400 + sodium tartrate + water, PEO1500 + sodium succinate + water, PPO400 + sodium succinate + water, PEO1500 + sodium citrate + water, PPO400 + sodium citrate + water and PPO400 + sodium acetate + water aqueous two-phase systems were determined at (283.15, 298.15, and 313.15) K. Both equilibrium phases composition were analyzed by conductimetry and refractive index. In this paper, the influences of polymer hydrophobicity, salt nature and temperature on the phase diagram were analyzed. The phase separation processes was endothermic and the hydrophobic increase make easier the phase splitting, while the electrolyte capacity to induce phase separation follow the order: citrate > tartrate > succinate. The consistency of the tie-line data was ascertained by applying the Othmer-Tobias correlation. The experimental data were correlated with the NRTL model for the activity coefficient, with estimation of new interaction energy parameters. The results, analyzed in terms of root mean square deviations between experimental and calculated compositions, were considered satisfactory.     

Drying dissipative structures of aqueous solution of poly(ethylene glycol) on a cover glass, a watch glass, and a glass dish

Drying dissipative structures of aqueous solution of poly(ethylene glycol) (PEG) of molecular weights ranging from 200 to 3,500,000 were studied on a cover glass, a watch glass, and a glass dish on macroscopic and microscopic scales. Any convectional and sedimentation patterns did not appear during the course of drying the PEG solutions. Several important findings on the drying patterns are reported. Firstly, the crystalline structures of the dried film changed from hedrites to spherulites as the molecular weight and/or concentration of PEG increased. Secondly, lamellae were formed along the ring patterns especially at high concentrations and high molecular weights. The coupled crystalline patterns of the spherulites and the lamellae were observed in a watch glass along the ring structures, supporting the important role of the convection by the gravity during the course of dryness. The coupled patterns were difficult to be formed on a cover glass and a glass dish, except at the outside edge of the dried film. Thirdly, the size of the broad ring at the outside edge of the dried film especially on a cover glass and a watch glass increased sharply as the molecular weight increased and also as the polymer concentration increased. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

聚己内酯-聚醚嵌段共聚物的光降解特性与机理

聚己内酯-聚醚嵌段共聚物(PCE)是一种可生物降解的高聚物[1].我们已经报道了PCE在体内及体外的降解特性,发现PCE的降解速度随着共聚物中聚醚含量的增加,温度升高,介质的酸碱性和酶的存在而加快.当PCE植入于动物体内,它的降解速度大大加快,因此PCE是一种极具应用前景的生物医用材料[2,3].     

Preparation of degradable polypropylene by an addition of poly(ethylene oxide) microcapsule containing TiO2 part II. Modification of calcium phosphate on the TiO2 surface and its effect

To prepare a novel photo-degradable polypropylene (PP) with a higher degradation rate, a PP composite containing a poly(ethylene oxide) (PEO)/modified TiO₂ microcapsule was prepared. The modification of the TiO₂ was performed by the synthesis of octacalcium phosphate intercalated with succinic acid ion (OCPC) under various Ca/P molar ratio conditions. It was found that the synthesis conditions of the Ca/P = 3.5 and 3.6 M ratios were suitable to prepare the OCPC. However, the microscopic composition on the TiO₂ surface was different between these Ca/P conditions and affected the PP photo-degradation rate in the PP/PEO/modified TiO₂ composite. It was found from the Fourier Transform Infrared (IR) and the tensile testing measurements that the existence of the OCPC covering material on the TiO₂ surface brought about the higher PP photo-degradation rate. The facilitation behavior of the degradation was due to the release of the acid species (succinic acid ion) from the OCPC in the degradation process. In addition, the higher coverage of the OCPC on the TiO₂ surface brought about an induction period for the degradation.     

Thermal degradation chemistry of poly(ethylene naphthalate) – A study by thermal volatilisation analysis

Although the fundamental degradation chemistry of poly(ethylene naphthalate), PEN, is thought to be similar to that of poly(ethylene terephthalate), PET, there is very little evidence in the literature to support this. This paper presents data on the thermal degradation of PEN, in comparison to PET, with particular reference to evolved gas analysis undertaken by thermal volatilisation analysis (TVA). Our thermal degradation studies highlight strong similarities in the degradation behaviour of PET and PEN, despite some evidence of increased thermal stability of PEN in comparison to PET. Identical primary and secondary thermal degradation mechanisms are proposed for PET and PEN, with radical degradation processes thought to dominate at high temperature.     

顺磁共振和紫外光谱法研究SDS-PEO体系的相互作用

合成更疏水的自旋探针4 羰基 2,2,6,6 四甲基哌啶氮氧自由基 2,4 二硝基苯腙.用顺磁共振（ESR）和紫外光谱法研究了十二烷基硫酸钠（SDS） 0.5 ％(w,质量分数)聚氧乙烯（PEO）体系的分子间相互作用. ESR结果表明,此水溶液体系的微极性随SDS浓度增大而减小,并且SDS与PEO聚集体具有更加紧密的堆积结构使其结合处具有较大的微粘性, SDS与PEO间的相互作用导致PEO分子链伸展. UV表明自旋探针分子可能靠近胶束的表面存在, 2,4 二硝基苯肼基团可能位于靠近SDS的硫酸根基团,定向于SDS胶束的表面,氮氧自由基基团短距离渗透到SDS胶束的碳氢核.     

The Synthesis of Poly(ethylene oxide)-Block-Polybutylacrylate

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Effect of UV irradiation on mechanical properties and structure of poly(1,3,4-oxadiazole) fibers

The accelerated ultraviolet aging behavior of poly(1,3,4-oxadiazole) fibers (POD fibers) exposed to artificial environment for different durations were studied. The influence of ultraviolet light on the intrinsic viscosity, structure, appearance and morphology, mechanical properties of POD fibers were investigated during aging by ATR-FTIR and UV-spectra, XPS, WXRD, SEM and tensile strength tester. The results revealed that the structure and properties of POD fibers were affected by UV light. Tensile strength and breaking elongation of POD fibers were severely decreased after 48 h UV light irradiation, and the change of intrinsic viscosity indicated that only degradation but not crosslink occurred. Disruption of oxadiazole rings and formation of carbonyl and amide were observed. UV aging process in nitrogen atmosphere suggested that the oxygen was indispensable and the essence of POD UV aging was photo-oxidation process. POD was amorphous and the recrystallization on surface was present after UV aging due to degradation. Morphology of POD fiber surface was damaged after UV aging.     

聚氧乙烯/粘土纳米复合材料的研究进展

聚氧乙烯(PEO)／粘土纳米复合材料．因为粘土的介入而具有更高的导电性、机械、热和界面稳定性，在电化学领域展现出了广泛的应用前景。本文对近十年来该材料的制备方法、插层结构、导电性、形态学以及流变学等研究进行了综述。     

Electrical conductivity of aqueous polymer solutions

 Theoretical equations were proposed to adequately simulate the electrical conductivity behavior of aqueous solutions of both charged and uncharged polymers. The theory, based on the mixture equation of Boned and Peyrelasse, was experimentally verified on poly(acrylic acid) (PAA) in water and poly(ethylene oxide) (PEO) in aqueous electrolyte solutions. The data analysis suggested that both the polymer coils may be depicted as oblate ellipsoids. Subsequently, the semiaxes values of the polymer coils were determined, and they were in good agreement with the results reported in the literature. Received: 25 June 1996 Accepted: 2 October 1996     

Novel degradable copolyesters containing poly(ethylene oxalate) units derived from diethylene oxalate

Two series of poly(ethylene terephthalate-co-oxalate-co-sebacate) (PETOXS) have been synthesized by melt polycondensation using diethylene oxalate (DEOX) as a starting material. NMR quantified the composition, structure, and average sequence length of the copolyesters. Melting and crystallization properties differ from each other on the basis of PETOXS feature. Analysis of TG traces determined that initial degradation temperatures were affected by the content of PET. It was observed that the Young's modulus and the maximum tensile stress increased with increasing content of poly(ethylene oxalate) (PEOX) in aliphatic units, whereas the elongation at break considerably decreased. Obvious weight loss was observed in alkali hydrolysis experiments, and the degradation rates are subject to distinct factors when the ratio of two aliphatic polyester units is varied. DSC was performed to degraded copolyester samples, and the variation of melting temperature and crystallinity were investigated.