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1.
Sorption and diffusion of a number of chlorinated alkanes through a diol chain extended polyurethane (PU) membranes have been investigated at 25, 40 and 60 degrees C, based on an immersion weight gain method. From the sorption result, the diffusion (D) and permeation (P) coefficients of halogenated hydrocarbon penetrants have been calculated. Molecular transport data depends on membrane-solvent interactions, size of the penetrants, temperature and also morphology of the chain extended PUs. The temperature dependence of the transport coefficient has been used to estimate the activation parameters for the process of diffusion (E(D)) and permeation (E(P)) from the Arrhenius plots. Furthermore, the sorption results have been interpreted interms of the thermodynamic parameters such as enthalpy and entropy.  相似文献   

2.
以异佛尔酮二异氰酸酯、二聚酸聚酯二醇(PDFA)、2,2-二羟甲基丙酸、1,4-丁二醇等为主要原料,采用季戊四醇二丙烯酸酯和丙烯酸羟乙酯分别在分子链的侧基和末端引入可UV固化的双键,制备出具有不同双键含量的可UV固化的水性聚氨酯PDFA-PU。红外光谱(FT-IR)分析证实了PDFA-PU的结构以及UV固化后双键的交联...  相似文献   

3.
Polyurethane (PU) elastomers were elaborated from polyethylene glycol of high molecular weight (MW = 4,000), 1,6-hexamethylene diisocyanate and polyethylene glycol (PEG1500) (MW = 1,500) as a long linear chain extender and/or castor oil as a cross-linker and were obtained in the form of transparent films. These poly(ether urethanes) elastomers are obtained by replacing the short-chain diol monomers with high molecular weight polyethylene glycols (PEG1500). High molecular weight polyethylene glycol (MW = 4,000 and 1,500, respectively) have greater chain length thus producing networks with lower cross-linking densities and higher average molecular weight between two consecutive cross-links. The PU properties were investigated using Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, mechanical analysis and thermogravimetry. The results showed that the prepared polyurethanes (PUs) had very good tensile properties. The stress–strain data show that the PU elastomers obtained using a 60/40% OHPEG1500/OHcastor oil ratio have the best mechanical properties. The thermal degradation of the castor oil cross-linked PU elastomers starts at 280–300 °C, compared to the thermal degradation of linear PUs which begins at 220 °C. During storage at 25 °C, the morphology and mechanical properties of the elastomer films have been observed to change in time.  相似文献   

4.
以聚乙二醇(PEG,Mn=600、1000)为引发剂,L-丙交酯(L-LA)为单体,在辛酸亚锡存在下开环聚合合成了三嵌段预聚物聚丙交酯-聚乙二醇-聚丙交酯(PLA-PEG-PLA),然后以具有有序结构的二氨基甲酸酯基二异氰酸酯(六亚甲基二异氰酸酯-1,4-丁二醇-六亚甲基二异氰酸酯,HBH)扩链制备了一种可生物降解的脂肪族聚氨酯(PU-I、PU-II)。作为对比,以4,4’-二苯基甲烷二异氰酸酯(MDI)作为扩链剂合成了芳香族聚氨酯(PU-III)。通过核磁共振、红外光谱、超高分辨质谱、凝胶渗透色谱等对预聚物、扩链剂、聚氨酯的化学结构进行了表征。通过对PU-I、PU-II和PU-III膜热性能、力学性能和体外降解性能的对比,研究了有序硬段对聚氨酯性能的影响。结果表明,相对于PU-III,PU-I具有更好的力学性能(断裂强度21 MPa,断裂伸长率840%)和较快的体外降解(19d);随着亲水链段PEG含量的增加,PU膜(PUII)的断裂强度降低,断裂伸长率增加,同时体外降解速率变快。该类型的脂肪族聚氨酯具有降解产物无毒、合适的力学性能和降解性能,可替代传统的芳香族聚氨酯,在医疗行业中有更广泛的用途。  相似文献   

5.
Polyurethane network films were prepared using polyester urethane acrylate (PUA) having terminal double-bond functional groups and acrylated epoxidized soybean oil (AESO). PUA elastomers were prepared by reacting polyester diol with diisocyanates, hexamethylene diamine, and acrylic acid. PUA/AESO network blends are synthesized by a simultaneous thermal polymerization process. The physical and thermal properties of the polymer networks obtained from the blend of AESO and polyester urethane urea acrylate were studied using FTIR-ATR, the thermal degradation behavior was studied by thermogravimetric analysis, differential scanning calorimetry, dynamic mechanical analysis, and tensile properties measurements being applied. The measurements were compared to the results for elastomers made from the PUA. The weight ratios of PUA/AESO affected the thermal and mechanical properties. With an increase in AESO content, the glass-transition temperature of the networks decreased from 40 to −4.8 °C, tensile strength increased from 1.7 to 9.8 MPa, and elongation at break decreased from 470 to 70%.  相似文献   

6.
不同端基聚氨酯-丙烯酸酯复合细乳液的表征   总被引:1,自引:0,他引:1  
采用异佛尔酮二异氰酸酯、聚丙二醇经1,4-丁二醇扩链的聚氨酯(PU),再经过甲醇或甲基丙烯酸羟乙酯封端后溶解在丙烯酸酯单体中,超声乳化后进行自由基细乳液聚合。NCO和OCH3为端基的PU构成的复合乳液GPC谱图都呈现两个峰,DSC和FT-IR分析发现,复合后增加了PU软段和硬段相分离的程度。甲基丙烯酸封端的复合乳液生成交联型聚合物,PU的硬段和硬段间的氢键也受到破坏。复合聚合物膜表面元素含量和本体接近,表明复合细乳液粒子未形成核-壳型结构。  相似文献   

7.
以聚己二酸乙二醇-丙二醇酯二醇(PEPA)为软段,分别采用4种二胺扩链剂和3种二异氰酸酯为硬段,通过预聚体法合成了一系列不同硬段结构和含量的聚氨酯脲弹性体,并采用红外光谱、热失重分析、差示扫描量热和拉伸测试等手段,研究了硬段类型及含量对聚氨酯脲性能的影响。结果表明,在软段结构一致,硬段含量接近的情况下,兼具柔性和刚性的硬段有助于提升聚氨酯脲的力学性能、热学性能和微相分离程度。几种二胺扩链剂和二异氰酸酯中,由二苯基甲烷二异氰酸酯(MDI)和4,4’-二氨基二苯醚(ODA)构成的硬段性能最佳;在软、硬段结构一致的情况下,硬段含量对聚氨酯脲性能影响明显。随着硬段含量增加,聚氨酯脲的拉伸强度、微相分离程度先增大后减小,5%热失重温度和断裂伸长率逐渐下降。当PEPA/MDI/ODA摩尔比为1∶0.5∶0.5(硬段含量31.7%),聚氨酯脲拉伸强度达51.5 MPa,断裂伸长率为709%,5%热失重温度为282.7℃,性能最佳。  相似文献   

8.
Thermal and tensile properties of HTPB-based PU with PVC blends   总被引:2,自引:0,他引:2  
Blends of HTPB (hydroxyl-terminated polybutadiene)-based polyurethane (PU) and polyvinyl chloride (PVC) membranes with various relative weight percentages were prepared by solution process. Different equivalent ratios of HTPB, 4,4′-dicyclohexyl methane diiscyanate (H12MDI), and 1,4-butane diol were used to synthesize PU solution by two-stage process. The intermolecular bonding between N-H, CO groups of PU and C-Cl group of PVC was determined via FTIR analysis by the relative absorbance of the two N-H groups and was correlated to thermal/mechanical properties. Larger part of PVC has been found to disperse in the hard domain of PU resulting in the shift in IR frequency. Thermal property, tensile strength and intermolecular bonding of membranes were function of the contents of PVC and PU's hard segment. One-year aged butadiene-containing PUs and blends still exhibit higher tensile strength than that of as-prepared ones. Hence, it is promising to replace the plasticizer, such as DOP, in PVC by these HTPB-based PU for the prevention of PVC migration as well as the enhancement of mechanical and thermal properties of blends.  相似文献   

9.
新型可紫外光固化水性聚氨酯的制备与表征   总被引:3,自引:2,他引:1  
以异佛尔酮二异氰酸酯(IPDI)、聚酯二元醇Pol-1256、二羟甲基丙酸(DMPA)为主要原料,采用预聚体法制备了水性聚氨酯预聚体,然后用自制的扩链剂对该预聚体进行扩链,并用丙烯酸羟乙酯(HEA)对扩链后的预聚体进行封端,最后中和乳化,制备了高紫外光(UV)固化基团含量的可UV固化水性聚氨酯乳液。采用FTIR对产物的结构进行了鉴定,利用旋转流变仪对分散体的流变性能进行了表征,通过TGA分析了UV固化膜的耐热性能,并对其拉伸性能进行了测试。研究结果表明:所制扩链剂符合预期结构特征,所得产物符合可UV固化的水性聚氨酯结构特征;乳液呈现出剪切变稀的特征,属于假塑性流体;UV固化膜具有良好的耐热性能,同时具有较高的断裂伸长率和良好的拉伸强度。  相似文献   

10.
This paper presents the effects of diol structure and acetoacetylation on cure, viscoelastic and mechanical properties of hydroxylated polyesters (HPS)/ hexamethoxymethylmelamine (HMMM) clear coatings. Acetoacetylation of HPs is a potential tool for researchers to get the equivalent or superior performance at higher application solids than their base counterpart. Differential Scanning Calorimetry (DSC), Dynamic Mechanical Thermal Analyzer (DMTA) and Thermo Gravimetric Analysis (TGA) have been utilized to study the cure, cure and viscoelastic behavior and thermal stability of the coatings respectively. The crosslink density (XLD) and elastically effective chain length between crosslinks (M c) of the coating films has also been determined. Furthermore, the mechanical film properties such as tensile properties, adhesion strength and hardness were measured and related to chemical composition. The results indicate that the combined analysis helps in correlating the structure property relationship with end use properties.  相似文献   

11.
The effect of variables such as shape template size, porogen composition and percentage, content of cross-linking monomer, and polymerization temperature on the properties of uniformly sized 3-microm porous poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads prepared by the staged templated suspension polymerization technique has been studied. The porous properties of the beads including surface morphology, pore size distribution, and specific surface area have been optimized to obtain highly efficient stationary phases for normal-phase HPLC. A column packed with diol stationary phase obtained by hydrolysis of poly(glycidyl methacrylate-co-ethylene dimethacrylate) beads affords an efficiency of 67,000 plates/m for toluene using THF as the mobile phase. The retention properties and selectivity of the diol beads are easily modulated by changes in the composition of the mobile phase. The performance of these beads is demonstrated with the separations of a variety of polar compounds including positional isomers, aniline derivatives, and basic tricyclic antidepressant drugs.  相似文献   

12.
Over the last 30 years, water-swellable and water-insoluble hydrogels have been extensively investigated and developed, leading to a large family of materials which have found uses in a wide range of biomedical applications. While hydrogels usually present a crosslinked structure, linear polyurethane-ureas (PUUs) based on poly(ethylene oxide) have been shown to be able to absorb and swell with aqueous media without dissolving. This behavior is due to the phase separated domain morphology, where hydrogen bonded urethane/urea hard segment domains are dispersed in a PEO soft segment domain. This work investigates the possibility of obtaining linear poly(ethylene oxide)-based polyurethane-amide (PUA) hydrogels using two amide diols as chain extenders, a mono amide diol (AD) and a diamide diol (DD), and a dicarboxylic acid (maleic acid, MA). Poly(ethylene oxide) based PUAs were obtained using a “one-shot” bulk polymerization technique. The chemicophysical characterization and water-solubility tests showed that these materials, while having molecular weights similar to the PUUs, do not possess sufficient phase separation, hydrogen bonding and hydrophobicity of the hard segment domains to exhibit hydrogel behavior. Crosslinked PUAs using maleic acid as chain extender show interesting hydrogel properties. © 1999 Kluwer Academic Publishers  相似文献   

13.
含有悬挂链结构的新型聚氨酯阻尼材料的研究   总被引:2,自引:0,他引:2  
在以甲苯二异氰酸酯(TDI)、六亚甲基二异氰酸酯(HDI)、聚四氢呋喃醚二醇(PTMG)、蓖麻油为原料的聚氨酯(PU)弹性体体系中加入了一种新型含有悬挂链结构的二元醇扩链剂,制得新型阻尼材料;论述了硬段及交联剂的种类和配比对PU阻尼性能的影响。结果表明:悬挂链结构二元醇扩链剂的加入,可有效提高PU弹性体在Tg之后的阻尼因子,显著改善其阻尼性能。  相似文献   

14.
通过酯化反应合成了四种含有不同体积的侧基结构的聚酯二元醇,然后以1,4-丁二醇和二苯基甲烷二异氰酸酯为扩链剂制备出聚氨酯胶膜。用凝胶渗透色谱(GPC)测定了聚酯二元醇的分子量,用差示扫描量热(DSC)分析了聚氨酯的热转变,通过分子量与酸值的变化对比了胶膜的耐水解性。研究结果表明,以2-乙基-1,3-己二醇为原料制备的聚氨酯胶膜由于具有较大体积的侧基结构,导致玻璃化温度降低、结晶能力降低。与以1,3-丙二醇为原料制备的聚氨酯胶膜相比,拉伸强度从28 MPa降低到15.2 MPa;但是水解失重最小、水解产物的酸值最低,表明大体积的侧基结构有助于提高聚氨酯胶膜的耐水解性。  相似文献   

15.
Polyurethane elastomers with potential for applications in damping bearings were synthesized with 1,6-hexamethylene diisocyanate, 4,4′-methylenebis-(phenylisocyanate), poly(1,4-butane)diols (Terathane 1400), 1,4-butane diol 1,6-hexane diol and glycerin chain extenders. The glass-transition temperatures of the materials ranged from −42 to −75 °C and were higher for polymers based on 4,4′-methylenebis-(phenylisocyanate) and with higher hard segment (HS) contents. The tensile strengths of the materials were 20–55 MPa and the tensile moduli were 30–134 MPa. These increased with increasing HS content. Interchain cross-linking improves thermal stability, which was measured by thermogravimetric analysis and differential scanning calorimetry. The structure and amount of HS used causes a significant variation in the properties of cross-linked elastomers.  相似文献   

16.
Several polyurethane-maleamides (PUMAs) containing polyether or polycarbonate soft segments, and aromatic or aliphatic hard segments were synthesized by solution or bulk polymerization, using maleic acid (MA) or a mixture of MA and butanediol as chain extenders. Using this process, activated double bonds are introduced into the polymer chains and the base polyurethanes may undergo further modification via specific grafting, thus improving their tissue compatibility. PUMAs chemicophysical properties were evaluated by gel permeation chromatography (GPC), intrinsic viscosity analyses, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR) and tensile mechanical tests. Polycarbonate diol (PCU)-based PUMAs showed higher molecular weights than polyether diol (PEU)-based ones. The use of butanediol in mixture with maleic acid led to an increase of molecular weights. FT-IR confirmed the presence of the bands related to the amide groups and to the conjugated double bond, yet more evident for the polymer obtained in solution. The higher crystallinity shown by this polymer was also indicative of a better phase separation. All the PCU-PUMAs exhibited similar tensile properties with a higher stiffness than PEU-PUMAs. Among the PEU-PUMAs, the highest tensile properties were shown by the polymer obtained in solution, and by the one derived from a mixture of maleic acid and butanediol.  相似文献   

17.
The tensile properties of brass (Cu-30% Zn)-nickel base metallic glass (MBF-35 Metglas) laminates have been investigated. Laminates were prepared by soldering these constituents together with a Pb−Sn alloy. The metallic glass exhibited an enhanced tensile ductility in the metal matrix environments, and such enhanced ductility depended on the metal matrix strength and elongation. Multiple shear bands have been observed in the metallic glass ribbon with enhanced tensile ductility. The failure modes of the laminates have been analysed based on stress-strain concentration concepts, following failure of the glass. The results were consistent with the experimental observations.  相似文献   

18.
Biodegradable radiopaque iodinated polyurethanes (I-PUs) based on poly(ε-caprolactone) diol (PCL) as soft segment have been synthesized using 4,4′-isopropylidene-(2,6-diiodophenol) (IBPA) as chain extender. In order to elucidate the effect of iodinated chain extender on degradation properties of I-PUs, a control polyurethane with bisphenol A as chain extender was also synthesized. The enzymatic degradation study of these I-PUs was carried out using phosphate-buffered solution (pH 7.4) at 37 °C. The mass loss, surface morphology, iodine content, radiopacity, hydrophilicity and thermal properties of the samples during degradation were characterized with scanning electron microscopy (SEM), energy-dispersive X-ray detector (EDX), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and static contact angle. Results of enzymatic degradation during 3 months indicated that the incorporation of iodinated chain extender greatly hindered the in vitro degradation of I-PUs compared with the control PU-C sample. The reason for the retarded degradation was attributed to the bulky iodine atoms on IBPA chain extender with steric hindrance, which decreased the surface hydrophilicity of I-PUs and slowed water/lipase diffusion rate. Moreover, the radiopacity of I-PUs does not sharply attenuate after long-time degradation, which is useful for interventional biomedical applications.  相似文献   

19.
为了开发利用玉米淀粉加工残余物(玉米醇溶蛋白)及制备环境友好刨花板,研究了二氯甲烷、玉米醇溶蛋白、制胶时搅拌温度等因素对基于玉米醇溶蛋白胶粘剂的木刨花板力学性能的影响。结果表明,当溶剂中二氯甲烷的体积百分含量在10%~50%范围内增加时,刨花板的静曲强度、弹性模量、抗拉强度及内结合强度等力学性能均呈现先增加后下降的趋势,当二氯甲烷含量为20%时,刨花板的各项力学性能达到最佳;当玉米醇溶蛋白的百分含量在20%~40%范围内增加时,刨花板的各项力学性能也均呈现先增加后下降的趋势,当玉米醇溶蛋白含量为30%时,刨花板的各项力学性能达到最佳;当制胶温度在25℃~65℃范围内增加时,刨花板的各项力学性能均呈现下降趋势,当温度为25℃时,刨花板的各项力学性能最佳。实验室测得玉米醇溶蛋白胶粘剂制备的刨花板力学性能值达到国家标准(GB4897-2003)。  相似文献   

20.
阳离子水性聚氨酯乳液的合成及性能   总被引:1,自引:0,他引:1  
以二异氰酸酯和聚酯二元醇合成聚氨酯预聚体,采用N-甲基二乙醇胺(N-MDEA)为亲水扩链剂,制备了阳离子水性聚氨酯(CWPU)乳液,研究了制备CWPU乳液的影响因素,并研究了CWPU乳液涂膜的拉伸性能。研究表明,当N-MDEA的质量分数为7.0%-9.5%,R值为1.3-1.5,中和度为80%-100%时,可制得稳定性较好的CWPU乳液。随着N-MDEA含量增加,CWPU乳液涂膜拉伸强度增加,断裂伸长率下降;随着中和度的提高,涂膜拉伸强度和断裂伸长率同时提高。  相似文献   

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