Electrospinning of sodium alginate with poly(ethylene oxide)

Another natural biopolymer, sodium alginate, has been electrospun from aqueous solution by blending with a non-toxic, biocompatible, synthetic polymer poly(ethylene oxide) (PEO). The interaction between sodium alginate and PEO has been evidenced by FTIR and conductivity change, which is thought to be the main reason for the successful electrospinning. The solution properties of sodium alginate/PEO blends have been measured, including viscosity, conductivity and surface tension. The morphology and mechanical properties of the electrospun mats have been investigated. Smooth fibers with diameters around 250 nm are obtained from 3% solutions of varied alginate/PEO proportions ranging from 1:1 to 0:1. Tensile strength around 4 MPa is found with smooth fiber mats. The anti-water property of the electrospun mats has been improved by a combination of hexamethylene diisocyanate and aqueous calcium chloride cross-linkings.     

Poly(ethylene oxide) and its blends with sodium alginate

A series of blends based on poly(ethylene oxide) (PEO) and sodium alginate (NaAlg) were prepared by solution casting method. The blends thus obtained were characterized by using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), tensile strength test, contact angle measurements and atomic force microscopy (AFM). FT-IR studies indicate that there are the hydrogen bonding interactions due to the ether oxygen of PEO and the hydroxyl groups of NaAlg. The thermal stability of the blends was slightly affected with increasing NaAlg content. DSC results showed that both melting point and crystallinity depend on the composition of the blends. Mechanical properties of the blend films were improved compared to those of homopolymers. Surface free energy components of the blend films were calculated from contact angle data of various liquids by using Van Oss-Good methodology. It was found that the surfaces both of the blends are enriched in low surface free energy component, i.e. NaAlg. This conclusion was further confirmed by the AFM images observation of the surface morphology of these blends.     

Alkali decomposition of poly(ethylene terephthalate) with sodium hydroxide in nonaqueous ethylene glycol: A study on recycling of terephthalic acid and ethylene glycol

Pellets of poly(ethylene terephthalate) (PET; 0.48–1.92 g) were heated in anhydrous ethylene glycol (EG; 5 mL) with 2-equivs of NaOH at 150°C for 80 min or 180°C for 15 min to convert them quantitatively to disodium terephthalate (Na₂-TPA) and EG. The disodium salt was precipitated quantitatively in pure state from the EG solution and separated readily. The other product EG, being the same component to the solvent, remains in the solution and can be obtained after distillation as a part of the solvent. The rate of decomposition was significantly accelerated by the addition of ethereal solvents to EG, such as dioxane, tetrahydrofuran, and dimethoxyethane. The reaction system is simple; no water and no extra reagent other than NaOH and EG are used. A few recycling systems of PET can be designed on the basis of the present alkali decomposition reaction. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 595–601, 1997     

乙烯渣油沥青的改性及表征

以乙烯渣油沥青为原料,通过常压空气氧化聚合处理对其进行改性,利用单因素方法考察了反应条件(反应温度、反应时间、空气流量)对改性沥青性质(软化点、喹啉不溶物、结焦值、甲苯不溶物、收率)的影响。结果表明,在反应温度370℃,反应时间5 h,空气流量24 L/h的条件下,可以获得软化点(SP)为233℃、喹啉不溶物(QI)为1.21%、结焦值(CV)为75.45%、甲苯不溶物(TI)为43.42%的改性沥青,其收率(Y)可达51.67%。通过元素分析、FTIR等手段对乙烯渣油沥青和改性沥青的芳香性指数(I_(ar))、支链化指数(CH_3/CH_2)进行计算,并利用TGA方法观察改性前后沥青的热稳定性变化。结果表明,乙烯渣油沥青和改性沥青的I_(ar)分别为0.39,0.53,CH_3/CH_2分别为0.88,1.08,说明改性过程中乙烯渣油沥青支链不断减少,芳香缩合度和热稳定性均有所提高。     

Study of electrospinning of sodium alginate,blended solutions of sodium alginate/poly(vinyl alcohol) and sodium alginate/poly(ethylene oxide)

Alginate is an interesting natural biopolymer for many of its merits and good biological properties. This paper investigates the electrospinning of sodium alginate (NaAlg), NaAlg/PVA‐ and NaAlg/PEO‐ blended systems. It was found in this research that although NaAlg can easily be dissolved in water, the aqueous NaAlg solution could not be electrospun into ultrafine nanofibers. To overcome the poor electrospinnability of NaAlg solution, synthetic polymers such as PEO and PVA solutions were blended with NaAlg solution to improve its spinnability. The SEM images of electrospun nanofibers showed that the alginate (2%, w/v)–PVA (8%, w/v) blended system in the volume ratio of 70 : 30 and the alginate (2%, w/v)–PEO (8% w/v) blended system in the volume ratio of 50 : 50 could be electrospun into finest and uniform nanofibers with average diameters of 118.3 nm (diameter distribution, 75.8–204 nm) and 99.1 nm (diameter distribution, 71–122 nm), respectively. Rheological studies showed a strong dependence of spinnability and fiber morphology on solution viscosity and thus on the alginate‐to‐synthetic polymer (PVA or PEO) blend ratios. FTIR studies indicate that there are the hydrogen bonding interactions due to the ether oxygen of PEO (or the hydroxyl groups of PVA) and the hydroxyl groups of NaAlg. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

碱法合成乙二醇钠盐的研究

本文研究了以乙二醇、NaOH为原料,采用有机芳烃溶剂作带水剂和反应溶剂,常压合成乙二醇钠。实验考察了反应物摩尔配比、反应温度、反应时间、溶剂用量等因素的影响。适宜的合成工艺条件为:乙二醇与NaOH的摩尔比为3~5∶1、反应温度100~180℃、反应时间4h,转化率达90%。     

Biosynthesis and characterization of bacteria cellulose–alginate film

A novel polysaccharide membrane containing alginate in bacterial cellulose matrix was synthesized by Acetobacter xylinum under static conditions using a culture medium supplementation with sodium alginate. By increasing alginate content, the bacterial cellulose–alginate (BCA) membrane was more hydrophilic and the film structure became denser with the smaller average pore size. Scanning electron microscope images displayed the deposits of alginate gel on the surfaces of the multilayer cellulose film. The declines in the tensile strength, the Young's modulus, and the elongation at break of the BCA membrane were dependent on the degree of alginate supplement. The BCA membrane showed higher water absorption capacity. The addition of alginate slightly affected the water vapor transmission rate but remarkably decreased the oxygen transmission rate of the membrane. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Modification of ethylene acrylic acid film for antimicrobial activity

Benzoyl chloride is commonly used as a food preservative to control microbial contamination by reducing the growth rate and maximum growth population and extending the lag period of the target microorganisms. Benzoyl chloride was successfully incorporated into a matrix of an ethylene acrylic acid polymer. The reaction of benzoyl chloride with ethylene acrylic acid was confirmed by Fourier transform infrared spectroscopy. The antimicrobial activity of modified ionomer films was studied through the monitoring of the growth of Penicillium sp. and Aspergillus sp. on the modified films. An untreated film did not show any inhibition of microbial growth. The inhibition activity was least in an ionomer film treated with acid and benzoyl chloride, and this was followed by a film treated with alkali and benzoyl chloride. The maximum inhibition was observed in a film treated just with benzoyl chloride. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3063–3068 2006     

Mechanical properties development of sodium alginate films with additives by UV‐radiation processing

To improve mechanical properties of polymer films; sodium alginate (SA) films was prepared with ethylene glycol (EG) and photocured. The formulation was prepared at various concentration with EG and photoinitiator (2%) in methanol. The mechanical properties were optimized in case of monomer (EG) concentration, soaking time, and radiation dose of intensities. The highest polymer loading (PL) was 7.1% and tensile strength (TS) of the film was 37.9 MPa were found for 3 min soaking in 5% EG containing formulation at 20th pass of UV radiation; the highest value (22%) of elongation at break (Eb) was obtained at 1 min soaking time at 15th passes of UV doses. The mechanical properties improvement of the films varied acrylic monomers; such as 2‐ethylhexylacrylate (EHA), 1,4‐butanediol diacrylate (BDDA), and trimethylpropane triacrylate (TMPTA) were used as additives (2%) in the optimized formulation. The highest PL (12.7%) and TS (42.2 MPa) of the films are at 5% EG, 2% TMPTA, and 2% photoinitiator in methanol at 3 min soaking time at 20th pass of UV radiation. The highest Eb (25%) was obtained using additives 2% EHA additives in 5% EG and 2% photoinitiator in methanol at 3 min soaking time. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

吸附剂的改性及脱除乙二醇中微量杂质

采用不同类型的吸附剂液相吸附处理乙二醇产品中微量杂质以提高其紫外透光率。实验结果表明采用活性炭进行吸附的效果优于凹凸棒石黏土和活性氧化铝。同时研究了不同改性条件下的活性炭对提高乙二醇紫外透光率的影响,结果显示经高温氨水还原改性后的活性炭吸附剂对乙二醇样品中影响紫外透光率杂质的去除效果最佳,经处理后乙二醇在220 nm、275 nm和350 nm处的紫外透光率值分别为81.23%、91.67%和99.23%,达到纤维级乙二醇标准。     

乙二醇单叔丁醚与乙二醇二叔丁醚的分离

在实验测定乙二醇单叔丁醚(TMBE)与乙二醇二叔丁醚(TDBE)相平衡数据的基础上,回归得到了Wilson方程的相互作用参数Λ12和Λ21,并利用回归参数的Wilson方程预测了TMBE和TDBE共沸组成随压力降低,TMBE的摩尔分数降低。根据此特性,文中设计了利用差压精馏分离TMBE和TDBE的流程,并在Pro/II流程模拟软件上,建立了差压精馏分离TMBE和TDBE的模型并进行了模拟计算。模拟结果表明:利用差压精馏可分别获得纯度(摩尔分数)大于99%以上的TMBE和TDBE。     

硫酸氢钠催化合成乙二醇单甲醚乙酸酯

将硫酸氢钠作为由乙二醇单甲醚和乙酸酯化合成乙二醇单甲醚乙酸酯的催化剂。研究了反应的影响因素和催化剂重复使用性能。当n(乙二醇单甲醚)∶n(乙酸)∶n(硫酸氢钠)＝1∶1.75∶0.003 62、苯为带水剂、回流分水60 min时,酯收率达90.0%。     

Preparation and characterization of poly(lactic acid)/poly(ethylene oxide) blend film: effects of poly(ethylene oxide) and poly(ethylene glycol) on the properties

Poly(lactic acid) (PLA) film plasticized with poly(ethylene oxide) (PEO) at various weight percentages (1–5 wt%) was prepared to improve the elongation, thus overcoming the inherent brittleness of the material. After optimization of the amount of PEO (4 wt%) through mechanical analysis, poly(ethylene glycol) (PEG), a well‐established plasticizer of PLA, was added (0.5–1.5 wt%) without hampering the transparency and tensile strength much, and again its amount was optimized (1 wt%). Neat PLA and PLA with the other components were solvent‐cast in the form of films using chloroform as a solvent. Improvement in elongation at break and reduction in tensile strength suggested a plasticizing effect of both PEO and PEG on PLA. Thermal and infrared data revealed that the addition of PEO induced β crystals in PLA. Scanning electron micrographs indicated a porous surface morphology of the blends. PEO alone in PLA exhibited the best optical clarity with higher percentage crystallinity, while PEG incorporation in PLA/PEO resulted in superior barrier properties. Also, the stability of the blends under a wide range of pH means prospective implementation of the films in packaging of food and non‐food‐grade products. © 2018 Society of Chemical Industry     

Structure–property modification of microcrystalline cellulose film using agar and propylene glycol alginate

Microcrystalline cellulose gum (MCG) forms edible films with poor physical and barrier properties. This study investigated the effects of incorporated agar and propylene glycol alginate (PGA) on structure and property of MCG films. The addition of agar and PGA modified the microstructure and reduced pinholes contributed to lower water vapor permeability (WVP) and improved tensile property of agar–MCG films. However, PGA–MCG had reduced tensile strength possibly due to incompatibility between polymer networks, however, showed a synergistic light barrier. The increased surface hydrophobicity (θ ～ 30°–75°) correlated well with decreased WVP for agar, PGA, and their composites which diverted from pure MCG films. The MCG reduced the thermal stability of agar; however, the PGA had no effect. Conversely, agar and PGA increased the thermal stability of the MCG component. The infrared spectra revealed insignificant H‐bonding and molecular interaction between polymers. Therefore, the results indicated that agar and PGA improved stability, mechanical, and barrier properties of edible MCG films via physical entanglement. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45533.     

Modification of unsaturated polyesters by poly(ethylene glycol) end groups

This article reports on the modification of unsaturated polyesters by poly(ethylene glycol) end groups in order to influence the solution behavior in styrene and to modify mechanical properties of the cured resin. The synthesis was done by the reaction of a carboxyl-terminated unsaturated polyester with various poly(ethylene glycol) mono-methyl ethers of molecular weights from 350 to 2000 g/mol. The characterization and curing properties of the synthesized block copolymers are presented. The glass transition temperatures decrease with increasing length of the poly(ethylene glycol) end groups. The introduction of long poly(ethylene glycol) end groups (2000 g/mol) leads to a phase separated and partly crystalline block copolymer with a melting point of 48°C. The block copolymers can be easily diluted in styrene to create the curable resins. The mixtures containing the block copolymers with the short poly(ethylene glycol) end groups (350 and 550 g/mol) could be cured in a reasonably short time. Compared to commercial unsaturated polyesters the mechanical testing revealed that the tensile strength is decreasing while the elongation is increasing. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 527–537, 1997     

Synthesis and characterization of ABA-triblock copolymers with poly(ethylene glycol) segments and LC-segments

This paper describes the synthesis of ABA-triblock copolymers with poly(ethylene glycol) A-blocks and a liquid crystalline polyester B-block. Three block copolymer series are presented with different block length of A- and B-blocks. The block copolymers show thermotropic liquid crystalline behavior up to a content of poly(ethylene glycol) segments of 50 wt%. Depending on their composition and chain length, the block copolymers are microphase separated or non-microphase separated. In the microphase separated block copolymers the poly(ethylene glycol) segments are able to crystallize. The degree of crystallinity and the spherulite diameter is strongly influenced by the length of the poly(ethylene glycol) segment itself as well as by the length of the incorporated polyester segment. Received: 19 December 1997/Revised version: 22 December 1997/Accepted: 22 December 1997     

Synthesis and characterization of polyester-imides from imidodicarboxylic acid monomers and ethylene glycol

Two monoimidodicarboxylic acids and four diimidodicarboxylic acids were synthesized from trimellitic anhydride and amino compounds, viz., glycine, p-aminobenzoic acid, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl methane, and 4,4'-diaminodiphenyl sulfide, and characterized by IR and ¹H-NMR spectroscopies and melting-point determination. These functional monomers were condensed in N-methyl-2-pyrrolidone solvent with ethylene glycol by a transesterification reaction to obtain the novel polyester-imides with backbones of alternate imide-ester linkages or imide-imide-ester-ester linkages with ? SO₂? , ? O? , ? CH₂? , or ? S? S? bridges in between. All the polymers were characterized by IR and ¹H-NMR spectroscopies, X-ray diffraction, solution viscosity, solubility and solubility parameters, and differential thermal analysis. Most of the polymers possess amorphous structure and fairly high decomposition temperatures (450–485°C). These polymers having solubility parameters in the range δ 11.44–11.85, as determined by the group contribution technique, are soluble at room temperatures in aprotic polar solvents. © 1993 John Wiley & Sons, Inc.     

Thin film composite sodium alginate membranes for dehydration of acetic acid and isobutanol

Dehydration of widely used organic solvents such as acetic acid (AA) and isobutanol (IB) is challenging tasks, which form close boiling mixtures with water. Sodium alginate (SA) thin film composite membranes were prepared and crosslinked with 2,4‐toluene diisocyanate (TDI) and glutaraldehyde for dehydration of IB and AA/water mixtures through pervaporation (PV). The crosslinked and uncrosslinked SA composite membranes were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, and universal testing machine for intermolecular interactions, crystalline nature, thermal stability, surface morphology, and tensile strength, respectively. At a feed composition of 98 wt % IB and 95 wt % AA aqueous solutions, the TDI crosslinked SA composite membrane exhibited separation factors of 3229 and 708 with reasonable fluxes of 0.021 and 0.012 kg m^?2 h^?1, respectively. The results obtained in the study for IB and AA systems were compared with other SA membranes reported in the literature. The membranes appeared to have potential for commercial PV ability to dehydrate the solvents up to desirable purity levels (>99%) and feasibility of preparing them in a composite form which would enable scale‐up into modular configurations. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40018.