Properties of urethane elastomers

Summary The dielectric relaxation processes in poly(azourethaneurea) prepared from diphenylmethane-4,4-diisocyanate (MDI) and poly(ethylene adipate) glycol were studied in the range 200–390 K using thermally stimulated depolarization currents (TSDC). The TSDC spectra obtained on original sample, annealed sample, and both annealed and stretched sample showed significant differences which were explained in terms of the supramolecular structure of polymers. It was accepted that the polymers have a multiphase supramolecular structure.     

Properties of urethane elastomers

Summary The thermally stimulated depolarization currents(TSDC) from polyurethanes based on 4,4-dibenzyle diisocyanate(DBDI) and both saturated and unsaturated polyesters were studied over the temperature range 240–410 °K. Pour relaxation peaks were observed. The structure of the TSDC thermograms, location and intensity of the constituent peaks depend both on the urethane content and thermal history of the polymerr The morphological structure of the samples was evidenced using electron microscopy method.     

Properties of urethane elastomers

Summary The dielectric relaxation processes in polyurethanes based on 4,4-dibenzyle diisocyanate and saturated polyester in the temperature range of 250–400°K using thermally stimulated depolarization currents method have been investigated. The structure of the relaxation thermograms, location and intensity of the constituent peaks depend both on the precipitation temperature and thermal history of the polymer. The relaxation processes have been associated with the molecular motions within domains with distinct morphological structures. The morphological structure of the samples was evidenced using electron microscopy method.     

蓖麻油基聚氨酯配合物的研究

采用蓖麻油、甘油、TDI等为原料,合成出端-NCO的蓖麻油基聚氨酯PU预聚体.对预聚体中NCO的含量进行了测定,采用FT-IR对材料进行了定性分析,对树脂的固化工艺进行了探讨.结果表明,蓖麻油基PU预聚体的NCO质量分数在4.93%～5.25%时,树脂在-18～40 ℃能固化成膜,表干时间＜1 h.     

Thermoelastic properties of urethane elastomers

Several polyurethanes based on poly(ethylene adipate), 4,4′-diphenylmethane diisocyanate, 1,4-butanediol, and 3,3′-dichloro-4,4′-diaminodiphenylmethane were prepared. The thermoelastic properties of these polyurethanes depend on compositional variables and are interpreted in terms of the extent and stability of microphase separation.     

Preparation and properties of castor oil-based polyurethanes

Four series of polyurethane elastomers were synthesized using diphenylmethane diisocyanate (MDI) and castor oil as the polyol. Two types of MDI (crude and distilled) were used. The temperature of reaction and the effect of excess isocyanate above stoichiometric were also varied. The structure of the polyurethanes was analyzed using wide-angle X-ray diffraction, scanning electron microscopy, and density and differential scanning calorimetry (DSC). Thermomechanical and dynamic mechanical (TMA and DMA) as well as mechanical measurements were carried out. The results have shown considerable influence of the type of MDI, excess of isocyanate, and temperature of preparation on the properties of the polyurethanes synthesized.     

蓖麻油基润滑油降凝剂的合成

以蓖麻油(CO)、甲基丙烯酸甲酯(MMA)为原料,偶氮二异丁腈(AIBN)为引发剂,甲苯为溶剂,无水无氧条件下合成了蓖麻油-甲基丙烯酸甲酯共聚物(PCOM).利用FTIR表征了PCOM的结构,用凝胶渗透色谱(GPC)测定了共聚物的相对分子质量及其分布,并对其降凝性能进行评价.结果表明,当m(CO):m(MMA)=1:1...     

Plasticizing effect of acetylated castor oil on castor oil-based,moisture-cured polyurethane film

Moisture-cured polyurethane films have been prepared by reaction between toluene diisocyanate and castor oil or derivatives such as castor oil diethanol amide, castor oil monoglyceride, ethylene glycol monoricinoleate, and propylene glycol monoricinoleate. Effect of acetylated castor oil as an internal plasticizer on the resulting urethane films has been studied. Catalytic effect of 3-5% triethanol amine on curing of plasticized films has been noted. Plasticized polyurethane films show good tensile strength (105-550 kg/cm²) and elongation (15-215%) properties, having high melting point (210-272 C) and good resistance to solvents and chemicals.     

蓖麻油基润滑油降凝剂的合成

以蓖麻油(CO)、甲基丙烯酸甲酯(MMA)为原料,偶氮二异丁腈(AIBN)为引发剂,甲苯作为溶剂,无水无氧条件下合成了蓖麻油-甲基丙烯酸甲酯共聚物。利用FTIR表征了蓖麻油-甲基丙烯酸甲酯共聚物的结构,用凝胶渗透色谱(GPC)测定了该聚合物的相对分子质量及其分布,并对其降凝性能进行了评价。结果表明：当m(CO):m(MMA)= 1:1、引发剂AIBN用量（引发剂用量占单体总质量的百分数）为0.25%、反应时间为8 h、反应温度为80 ℃时,收率为59.20%,聚合物相对分子质量为2.722×105,相对分子质量分布较窄（PDI=1.51）。且共聚物对润滑油具有一定降凝效果,当共聚物添加量（聚合物质量占油品质量的百分数）为0.5%时,凝点(SP)可降低10 ℃ (ΔSP=10 ℃)。     

Rigid urethane foams from blown castor oils

Solvent-blown rigid urethane foams prepared from a low-cost polyol mixture composed of raw castor oil and triisopropanolamine have been described. Foams with higher compressive strengths can be obtained by substituting oxidized (blown) castor oil for the raw castor oil in formulations of this type. The properties of rigid foams prepared from several commercial blown castor oils are described. The properties of these foams are correlated with the degree of oxidation of the blown oils used, as indicated by their oxygen content, density, viscosity, and refractive index. Removal of acid from blown oils having high acid values has no significant effect on the compressive strength of foams prepared from these oils. When blown castor oil is used instead of raw castor oil, less isocyanate is required to produce a urethane foam of specified density and compressive strength. Presented at the AOCS meeting in Toronto, Canada, 1962. A laboratory of the W. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

Microphase separation and properties of urethane elastomers

Several polyurethanes were prepared from poly(ethylene adipate)glycol, 4,4′-diphenylmethane diisocyanate, 1,4-butanediol, or 3,3′-dichloro-4,4′-diaminodiphenylmethane. Thermomechanical curves were determined for all investigated systems, and the glass transitions found thereof formed the basis of subsequent analysis. The analysis showed that the investigated systems belonged to those polyurethanes that can undergo microphase separation. It was also shown that the separation in the diamine-extended elastomers was less sensitive to changes in chemical composition than in the diol-extended systems. The diamine-based polyurethanes were also closer to the ideal separation than the diol-extended elastomers. Examinations of elastomers of varying amount of chemical crosslinking revealed a joint action of the crosslinking and microphase separation in determining mechanical properties of the systems. Together with swelling measurements, the examinations showed that optimum mechanical properties were obtained while keeping a very careful balance between these two factors.     

丙烯酸酯改性蓖麻油基水性聚氨酯乳液的制备

以改性蓖麻油(MCO)、聚碳酸酯二醇(PCDL)、异佛尔酮二异氰酸酯(IPDI)、六亚甲基二异氰酸酯(HDI)和二羟甲基丙酸(DMPA)等为原料合成水性聚氨酯种子乳液,通过MCO的双键活性位实现丙烯酸酯(AC)单体的种子乳液聚合,得到聚氨酯–丙烯酸酯(PUA)乳液。通过FT–IR(傅里叶变换红外光谱)分析、激光粒度仪、旋转黏度计研究了AC单体含量及配比、助剂用量对PUA乳液性能的影响。通过电子拉力试验机、耐水试验和动态力学分析仪研究了不同AC含量PUA膜的力学、耐水和动态力学性能。结果表明:通过种子乳液共聚,PUA均显示一个玻璃化温度,说明聚丙烯酸酯与聚氨酯具有较好的相容性;当n(MCO):n(PCDL)=1.2,n(甲基丙烯酸正丁酯):n(甲基丙烯酸甲酯)=0.9,w(乳化剂SDS)为2.0%,w(引发剂AIBN)为0.2%时所合成的PUA稳定性最好,且具有适中的黏度和较好的粒径分布;随AC含量的提高,PUA胶膜耐水性提高,胶膜硬度和弹性模量逐渐提高,拉伸强度和伸长率均在w(AC)为10%时出现最大值。     

Viscoelastic properties and heat generation in urethane elastomers

Static and dynamic properties were studied in a series of polyurethane elastomers as a function of selected compositional variables such as curative system, curative level, catalyst level, and curing temperature. A number of physical properties including swelling ratio, density, glass transition temperature, stress–strain behavior, and thermal conductivity were also measured on these elastomers. The selected variables affect dynamic mechanical properties as well as heat buildup. A good correlation was noted between the loss modulus and the heat generation. The loss modulus and the heat generation decrease with decreasing curative level. The elastomers cured with a mixture of triol and diamine give lower loss modulus and heat buildup than those cured with diamine alone. These responses are believed due to the increase in covalent crosslinks. The observed low heat generation of the elastomer cured with 0.2 phr azelaic acid as a catalyst level was also attributed to the high crosslink density. The curing temperature, in the range investigated, appears to have very little effect on the properties. Thus, the choice of formulation variables, especially the use of diamine–triol blends, provides an effective means of minimizing heat generation in dynamic applications of polyurethane elastomers.     

Isocyanate terminated castor oil-based polyurethane prepolymer: Synthesis and characterization

The use of new materials from natural origin in the synthesis of urethane-derived polymers is recently drawing eminent care from social, environmental and also economic viewpoints. In this work, NCO-terminated castor oil-based polyurethane prepolymer (COPUP) is synthesized through the reaction between the isophorone diisocyanate (IPDI) and castor oil (CO) with a variable ratio of the isocyanate (NCO) and hydroxyl (OH) groups (0.5:1; 1:1; 1.5:1; 2:1) analyzed by nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy. Furthermore, the polyurethane prepolymers synthesized from IPDI played a significant role of inter-mixing between the soft polyether segments and the hard urethane groups, as shown by the analysis of hydrogen bonding in FT-IR deconvolution. A detailed study of the relationship between structure–property of cured prepolymers was carried out. As a result, COPUP obtained from biomass-derived polyols may enhance a promising alternative to the use of other petrochemicals in the paving industry.     

Synthesis and characterization of castor oil urethane triamine networks

Castor oil was polymerized with diisocyanate and crosslinked with primary triamine (Jeffamine T-403) to form networks. The effect of triamine as a crosslinking agent on rubbery castor oil urethane elastomer was determined by measuring network parameters such as average molecular weight between crosslinks (MC) number of polymer chains per unit volume (N), tensile strength, and modulus of the networks. The crosslinking density was varied by varying the ratio of NCO : NH₂ from 0.60 to 0.95. The results indicated the formation of highly crosslinked elastomers at all NCO : NH₂ ratios employed. The tensile stregth and modulus increased with increasing crosslink density up to a value of NCO : NH₂ 0.85 and after this there was no significant change, indicating the maximum limit of improvement attainble in terms of network characteristics.     

Semi-interpenetrating polymer networks from castor oil-based polyurethane and nitrokonjac glucomannan

New semi-interpenetrating polymer networks (semi-IPNs) coded as PUNK were successfully synthesized from castor oil-based polyurethane (PU) prepolymer and 10–40 wt % nitrokonjac glucomannan (NKGM) containing a degree of substitution of 2.4 and a weight-average molecular weight of 4.75 × 10⁴. The semi-IPN sheets that were 100 μm thick were cured more speedily than PU, with curing times of 5 h for PUNK and 16 h for PU at 50–70°C. The structure and miscibility of the semi-IPN sheets were studied by Fourier transform infrared spectroscopy, ultraviolet spectroscopy, and scanning electron microscopy. The results showed that a strong intermolecular interaction caused by hydrogen bonding between NKGM and PU exists in PUNK, resulting in good miscibility. When the NKGM content of the semi-IPNs sheets was 20 wt %, the tensile strength and light transmittance were obviously higher than that of the PU sheets. The NKGM in the semi-IPN sheets plays an important role not only in accelerating the cure but also in improving the mechanical properties and biodegradability. As a new material prepared from renewable resources, PUNK has potential applications because of its biodegradability. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2076–2083, 2001     

Semi-interpenetrating polymer networks from castor oil-based polyurethanes and chlorinated rubber

Semi-interpenetrating polymer networks (semi-IPNs) were prepared by crosslinking castor oil in the presence of chlorinated rubber. Crosslinking in toluene solution was effected with 2,4-toluene diisocyanate or hexamethylene diisocyanate at various NCO/OH ratios. The semi-IPNs were obtained as tough films and were characterized by their mechanical, thermal, morphological and electrical properties.     

无皂核壳蓖麻油基聚氨酯苯丙杂化乳液

以蓖麻油、异佛尔酮二异氰酸酯(IPDI)和二羟甲基丙酸(DMPA)为主要原料制得具有表面活性的蓖麻油基聚氨酯水分散体(CPU),采用红外光谱(FT-IR)、核磁共振(NMR)表征了其结构,测定其临界胶束浓度(CMC)为70g/L。在CPU中进行苯乙烯(St)与丙烯酸丁酯(BA)的共聚合,制备了无皂核壳杂化乳液。通过胶膜吸水率、铅笔硬度和冲击强度测试,研究了CPU中蓖麻油及DMPA的用量对杂化乳液性能的影响,确定了较佳用量为:IPDI19.25g,蓖麻油30g,DMPA3.71g。采用透射电镜(TEM)和FT-IR表征了杂化乳液的结构,并采用热重(TG)、示差扫描量热仪(DSC)表征了乳胶膜的热性能。结果表明,杂化乳液具有清晰的核壳结构;当m(壳)∶m(核)=6∶4,核中单体m(St)∶m(BA)=7∶3时,可制得硬度为3H、吸水率为5.9%、耐冲击强度为54kg·cm的杂化膜。     

环氧改性蓖麻油基WPUA纸张施胶剂的研究

以蓖麻油和IPDI(异佛尔酮二异氰酸酯)溶于St(苯乙烯)、BA(丙烯酸丁酯)中制备聚氨酯预聚体,再以MDEA(N-甲基-二乙醇胺)和BDO(1,4-丁二醇)扩链,后用环氧树脂E-44为改性剂,制得EWPUA(环氧树脂改性蓖麻油基阳离子型水性聚氨酯-丙烯酸酯)复合乳液。研究结果表明:环氧基成功地引入到聚合物分子链中;当w(E-44)=4%时,EWPUA乳液具有优异的表面施胶性能。以w(EWPUA)=1%进行表面施胶,纸张施胶度达54 s,抗张强度增加至33.4 N/mm~2,耐破度由89 kPa增加至166 kPa,接触角由82°增加至128°,拉伸强度由5.08 MPa增加至8.86 MPa。