异氰酸酯指数对蓖麻油基聚氨酯弹性体性能的影响

以蓖麻油和其衍生物多元醇、液化MDI与2-乙基-1,3-己二醇为原料,通过一步法制备了异氰酸酯指数(R值)≥1. 0的聚氨酯弹性体(PUE)。通过溶胀度、力学性能、差示扫描量热、热失重、吸水率和水解性能测试,研究了R值对PUE性能的影响。结果表明:增大R值可以提高PUE交联密度,从而使得其拉伸强度和软段玻璃化转变温度提高,断裂伸长率和吸水率减小;在70℃不同水介质中水解30 d后,PUE在碱液中水解最为严重,R值≥1. 2时,PUE质量损失率0. 5%,拉伸强度保持率≥92%。     

光学透明的硅烷改性聚氨酯胶粘剂的研究

以聚碳酸酯二醇、1,4-丁二醇、3-异氰酸酯基丙基三甲氧基硅烷为原料，通过加入不同的异氰酸酯单体制备了不同的硅烷改性聚氨酯胶粘剂，研究异氰酸酯类型对硅烷改性聚氨酯胶粘剂的力学性能、光学性能、流变性能、热稳定性的影响。结果表明:使用二环己基甲烷二异氰酸酯(HMDI)制备的硅烷改性聚氨酯胶粘剂相对于六亚甲基二异氰酸酯(HDI)、异佛尔酮二异氰酸酯(IPDI)性能更佳，其PET/玻璃剥离强度为17.70 N(样条宽15 mm)，可见光透过率为99.45%，玻璃化转变温度为-20.04℃。     

木素型聚氨酯的合成与性能研究

利用木素和两种二异氰酸酯合成了聚氨酯，对其热性能、力学性能、膨胀性能进行了测试。结果表明，羟丙基基化改性将木素变为聚酯－醚多元醇，可与二异氰酸酯合成木素聚氨酯；异氰酸酯基与羟基配比对用TDI与HDI合成的聚氨酯性能影响不同。     

聚氨酯丙烯酸酯涂料的性能研究

合成了具有不同玻璃化温度、羟值、酸值和相对分子质量的羟基丙烯酸树脂,并采用HDI多异氰酸酯作为固化剂,研究了羟基丙烯酸树脂对双组分聚氨酯涂料性能的影响,结果表明:玻璃化温度、羟值和酸值对聚氨酯涂料的适用期、干燥时间、漆膜硬度、凝胶率等有较大影响;相对分子质量对这些性能的影响较小;漆膜中苯乙烯含量越高,漆膜耐候性越差.     

间苯二胺扩链的芳香族聚氨酯弹性体的合成与性能

以甲苯二异氰酸酯和聚氧化丙烯二元醇合成聚氨酯预聚体,通过间苯二胺扩链,得到一种芳香族聚氨酯弹性体。探讨了异氰酸根指数(R值)对聚氨酯预聚体和弹性体合成及固化行为的影响;并利用FT-IR、DSC和拉伸实验等对合成聚氨酯的结构、组成、热性能和力学性能等进行了表征。结果表明,随着R值的增加,聚氨酯弹性体的凝胶时间和表干时间逐渐缩短,拉伸强度增大,断裂伸长率降低,硬段的玻璃化转变温度和热分解温度升高;R值为2.0、2.5和3.0时,合成了固化参数适宜、拉伸性能优异、可用于混凝土防护的聚氨酯弹性体材料。     

蓖麻油聚氨酯互穿网络型聚合物性能的研究

分别用甲苯二异氰酸酯(TDI)和六亚甲基二异氰酸酯(HDI)与蓖麻油(CO)反应制备出两种聚氨酯预聚体,再用预聚体与苯乙烯、丙烯腈、甲基丙烯酸甲酯、环氧树脂(E-44或E-51)等单体制备出蓖麻油聚氨酯互穿网络型聚合物(CO-PU IPN),研究了体系组成对该聚合物拉伸强度的影响。结果表明,随着固化时间的延长,CO-PU IPN的拉伸强度逐渐增大,TDI型CO-PU IPN比HDI型的拉伸强度大;烯类单体比环氧树脂单体所制CO-PU IPN的拉伸强度大,不同烯类单体之间的差别不大;增加预聚体中NCO/OH的摩尔比,CO-PU IPN的拉伸强度都是先增加,后减小,在摩尔比为2.25时出现最大值;添加抗氧剂1010、紫外光吸收剂UV-327和光稳定剂292等对CO-PUIPN的拉伸强度基本没有影响。     

甲苯二异氰酸酯交联阳离子型丙烯酸酯树脂的制备及性能

用自由基聚合法制备了阳离子型羟基丙烯酸酯树脂,以甲苯-2,4-二异氰酸酯(TDI)和丁酮肟合成出半封端型TDI,将两种产物混合反应,制备出系列聚氨酯改性的丙烯酸酯树脂分散液.分散液成膜后,在高温(140 ℃)下解封的异氰酸酯官能团与丙烯酸酯树脂上的羟基反应得到异氰酸酯交联丙烯酸酯树脂膜.结果表明,随着交联度的提高,丙烯酸酯树脂的玻璃化转变温度升高,凝胶含量增加,拉伸性能、邵尔A硬度、耐腐蚀性及耐水性得以提高.     

可再生多元醇蓖麻油基聚氨酯灌封胶的制备与性能研究

以蓖麻油、聚醚多元醇(PPG)、液化MDI为主要原料,以1,2-丙二醇(PDO)为扩链剂,采用预聚体法合成制备出聚氨酯灌封胶,讨论了异氰酸酯指数R、硬段质量分数等对聚氨酯灌封胶性能的影响。结果表明:随硬段质量分数、R值的增加,材料的硬度、拉伸强度上升,而断裂伸长率降低;聚氨酯耐水解性(吸水率≤0.366%)好,起始分解温度(277℃)高,热稳定性好;阻尼性能随R值增加而减少,玻璃化转变温度向高温方向移动,且材料软硬段相容性较好。     

端胺基非异氰酸酯预聚体嵌段共聚聚醚型聚氨酯

用端胺基非异氰酸酯基聚氨酯预聚体与聚醚型聚氨酯预聚体嵌段共聚制备了改性聚醚型聚氨酯及其膜,分析了端胺基非异氰酸酯基聚氨酯预聚体,考查了聚醚型聚氨脂树脂成膜温度和预聚体NCO/ NH2配比对膜力学性能的影响,同时对比了聚氨酯材料的力学性能,采用差示扫描量热法（DSC）研究了相分离程度。结果表明,合成的端胺基非异氰酸酯基聚氨酯预聚体中成功地引入了氨基甲酸酯基团;最佳成膜温度为140 ℃;当预聚体NCO/NH2=1/0.9（摩尔比,下同）时膜的性能最好,拉伸强度为25.1 MPa,伸长100 %模量为5 MPa,;与普通聚氨酯相比,端胺基非异氰酸酯基聚氨酯预聚体嵌段的聚氨酯力学性能更高;DSC曲线显示其有2个不同的玻璃化转变温度,相分离明显。     

交联剂用量对聚氨酯乳液膜性能的影响

由聚醚、甲苯二异氰酸酯、二羟甲基丙酸及三羟甲基丙烷（TMP）等为原料制备交联型聚氨酯乳液。乳液胶膜的性能受交联剂TMP用量影响。交联剂用量越大,胶膜的玻璃化温度越高、断裂伸长率越小、在甲苯中溶胀性越小。当交联剂的摩尔分数约为3％时,拉伸强度最大,吸水率和浸水失重率最小。     

Engineering plastics from lignin. III. Structure property relationships in solution cast polyurethane films

Lignin-based polyurethane films were synthesized by solution casting from hydroxypropyl lignin derivatives and either an aliphatic or an aromatic isocyanate. Two lignins, kraft and steam explosion lignin, and two diisocyanates, hexamethylene diisocyanate (HDI) and tolylene diisocyanate (TDI), were chosen for the study. It was found necessary to use stoichiometric excess diisocyanate in the synthesis of the thermosetting polyurethanes. This part of the series addresses the effect of synthesis variables on film properties. The study examines the effect of lignin type, of diisocyanate type, and of composition in terms of NCO to OH stoichiometry on thermal and mechanical properties. Stoichiometric NCO-excess was found to cause a more significant increase in the glass transition temperature of TDI-based films than of films made with HDI. The films swelled less with increasing NCO/OH ratio. Use of aliphatic diisocyanate (HDI) resulted in films with lower moduli as compared to aromatic diisocyanate (TDI). Kraft-lignin-based polyurethanes had slightly inferior strength characteristics (Young's modulus and tensile strength) in comparison with those derived from steam explosion lignin. Variation in the NCO/OH stoichiometry had no noticeable effect on modulus or tensile strength, but did significantly influence glass transition temperature, swelling, and strain at break. It is observed that the properties of these thermosetting polyurethanes are very sensitive to their composition. The study illustrates that materials of satisfactory performance characteristics can be engineered by proper selection of synthesis variables and modification of network architecture.     

Preliminary studies on the use of modified ALCELL lignin as a coupling agent in the biofiber composites

ALCELL lignin has been employed as a coupling agent in empty fruit bunch fiber (EFBF)–polypropylene (PP) composites. The lignin has been chemically modified with toluene diisocyanate (TDI) to various weight loadings. The evidence of the reaction between TDI and lignin has been observed by using Fourier transform infrared (FTIR) analysis. The effect of lignin as a coupling agent on mechanical properties has been studied. The results show that the TDI‐modified lignin is able to impart greater compatibility between EFBF and PP. This is reflected in the greater mechanical properties shown by the composites with TDI‐modified lignin than in those with the unmodified lignin. Scanning electron microscopy (SEM) studies showed that TDI modification of lignin resulted in a better blending and compatibility between lignin and PP matrix. The glass‐transition temperature of the lignin increases as the WPG is increased. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1333–1340, 2001     

Polyurethanes with monodisperse rigid segments based on a diamine–diamide chain extender

Polyether(bisurethane‐bisurea‐bisamide)s (PEUUA) based on poly(tetramethylene oxide) (PTMO) were synthesized by chain extension of PTMO endcapped with a diisocyanate (DI), and a diamine–diamide extender. The prepolymers were PTMOs with molecular weights between 1270 and 2200 g mol^?1, either endcapped with 4,4′‐diphenylmethane diisocyanate (MDI), 2,4‐toluene diisocyanate (2,4‐TDI), or 1,6‐hexane diisocyante (HDI) and with a low content of free diisocyanate (<0.1 wt %). The diamine–diamide (6A6) extender was based on hexamethylene diamine (6) and adipic acid (A). In this way, segmented polyurethanes with monodisperse rigid segments (DI‐6A6‐DI) were obtained. The PEUUAs were characterized by DSC as well as temperature‐dependent FTIR and DMTA. The mechanical properties of the polymers were evaluated by compression set and tensile test measurements. The polyurethanes with monodisperse rigid segments displayed low glass transition temperatures, almost temperature‐independent rubbery plateaus and sharp melting temperatures. The crystallinities of the hard segments were 70–80% upon heating and 40–60% upon cooling. The rate of crystallization was moderately fast as the supercooling (T_m ? T_c) was in the order 36–54°C. The polyurethanes based on HDI had a much higher rubber modulus as compared to the MDI and 2,4‐TDI‐based polymers, because of a higher degree of crystallinity and/or a higher aspect ratio of the crystallites. The HDI residues are flexible and not sterically hindered and could therefore be more easily packed than MDI or 2,4‐TDI residues. Polyurethanes with monodisperse DI‐6A6‐DI hard segments have interesting properties. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of the diisocyanate structure and the molecular weight of diols on bio‐based polyurethanes

Bio‐based polyurethanes (PU) containing poly(ε‐caprolactone) diol (PCL) and hydroxyl telechelic natural rubber (HTNR) were synthesized. The effect of the diisocyanate structure and the molecular weights of diols on the mechanical properties of PU were investigated. Three different molecular structures of diisocyanate were employed: an aliphatic diisocyanate (hexamethylene diisocyanate, HDI), an aromatic diisocyanate (toluene‐2,4‐diisocyanate, TDI) and a cycloalkane diisocyanate (isophorone diisocyanate, IPDI). Two molecular weights of each diol were selected. When HDI was employed, a crystalline PU was generated while asymmetrical structures of TDI and IPDI provided an amorphous PU. The presence of crystalline domains was responsible of a change in tensile behavior and physical properties. PU containing TDI and IPDI showed a rubber‐like behavior: low Young's modulus and high elongation at break. The crystalline domains in PU containing HDI acted as physical crosslinks, enhancing the Young's modulus and reducing the elongation at break, and they are responsible of the plastic yielding. The crystallinity increased the tear strength, the hardness and the thermal stability of PU. There was no significant difference between the TDI and IPDI on the mechanical properties and the physical characteristics. Higher molecular weight of PCL diol changed tensile behavior from the rubber‐like materials to the plastic yielding. Thermal and dynamic mechanical properties were determined by using DSC, TGA and DMTA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

低不饱和度聚醚PU弹性体力学性能的研究

研究了以不同相对分子质量的低不饱和度聚醚多元醇、二异氰酸酯(MDI.TDI)和扩链剂(1．4-BDO．MOCA)为原料制备PU弹性体的力学性能。结果表明：PU弹性体的硬度、拉伸强度和撕裂强度随NCO基含量增加而提高。逐渐提高聚醚的相对分子质量，PU的拉伸强度和撕裂强度下降,冲击弹性提高。相对分子质量为2000的TDB-PU比相同相对分子质量PPG-PU的综合力学性能要好。     

Polyurethane from kraft lignin

The condensation of lignin with hexamethylene diisocyanate (HDI) or of a mixture of lignin-poly(ethylene oxide) (PEO) with HDI was investigated. The lignin used in this study was a kraft lignin from Pinus maritima, and was obtained from black liquor by acidification, filtration and vacuum drying. Thermogravimetric analysis was carried out to compare the weight loss against temperature of polyurethanes based on kraft lignin and hexamethylene diisocyanate, or of mixed polyurethanes lignin-PEO-HDI, with that of kraft lignin alone. It was shown that lignin can react with isocyanates in rather mild conditions to give polyurethanes, confirming previous results performed with model molecules. Some mechanical properties (Young's modulus and rupture strength) and glass transition temperature were also measured on the various above materials. In all cases it was concluded that lignin participates to the polycondensation reaction. As to rigid foams, it was found that polyurethanes prepared with oxypropylated glycerol, ethylene glycol and kraft lignin, in the weight proportions of 100/30/15, and HDI had good dimensional stability, and thermal and mechanical properties comparable to those of equivalent industrial materials.     

Natural castor oil based 2-package waterborne polyurethane wood coatings

The effects of four kinds of hardener on the properties of castor oil (CO) based 2-package waterborne polyurethane (2K-WPU) wood coatings were examined. Modified castor oil (MCO) was prepared by transesterification of glycerol and CO at the molar ratio of 2.0. The waterborne polyurethane-dispersed polyol (PUDp), one component of the 2K-WPU, was synthesized from MCO, dimethylol propionic acid (DMPA) and isophorone diisocyanate (IPDI) by the acetone process to provide a prepolymer with a carboxyl and hydroxyl groups. Then the prepolymer was neutralized by triethylamine (TEA) and dispersed into water. After vacuum distillation to remove acetone, the PUDp was obtained and then mixed with four different hardeners: IPDI, hexamethylene diisocyanate (HDI), polyethylene glycol (PEG) modified PIPDI (polymeric IPDI) and PEG-modified PHDI (polymeric HDI). The NCO/OH molar ratio of 1.5 was used and a 2K-WPU coating was obtained. The results showed that the film of the 2K-WPU coatings obtained from IPDI hardener had excellent gloss and hardness. On the contrary, the film containing PEG-modified PIPDI hardener (PEG-PIPDI) had lower hardness and gloss but higher tensile strength. The film containing PEG-modified PHDI hardener (PEG-PHDI) showed the best elongation at break, abrasion resistance and impact resistance, though it had the worst hardness. The film with HDI hardener had the best hardness and highest tensile strength and superior water resistance among all the films with different hardeners, and it was suitable for wood coatings.     

Toughening epoxy resin with blocked isocyanate containing soft chain

A series of imidazole (MI) blocked 2,4‐toluene diisocyanate (TDI) with polyethylene glycol (PEG‐400) as soft segment (PEG‐MI‐b‐TDI) were synthesized for toughening and curing the bisphenol A type epoxy resin (E‐44). Fourier transform infrared (FTIR) spectrum indicates that the NCO groups of the isocyanate molecule are blocked with MI. For curing epoxy systems, elimination of epoxy group and the formation of urethane bonds were studied by FTIR spectroscopy. The results of mechanical property were shown that the tensile shear and impact strengths of neat MI and MI‐b‐TDI cured E‐44 are lower than those of PEG‐MI‐b‐TDI cured E‐44. Based on the scanning electron microscope studies, microstructure evolutions of the E‐44 cured by different curing agents were imaged. The mechanical, thermal, and dynamic mechanical properties were measured by universal testing machine, differential scanning calorimeter and dynamic mechanical analyzer (DMA). The toughness of E‐44 cured by PEG‐MI‐b‐TDI was effectively improved without sacrificing the tensile shear strength. Based on the DMA studies, the long soft chain of PEG brought in a noticeable lowering in the glass transition temperature (T_g). The glass transition temperature is near 165°C for the neat MI cured E‐44, which is higher than the T_gs of the other curing agents cured epoxy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41345.     

Microphase-separated structure and mechanical properties of norbornane diisocyanate-based polyurethanes

Norbornane diisocyanate (NBDI: 2,5(2,6)-bis(isocyanatomethyl)bicyclo[2.2.1]heptane) is a new commercialized diisocyanate. NBDI-based polyurethane elastomers (PUEs) were prepared from poly(oxytetramethylene) glycol (PTMG), NBDI and 1,4-butanediol (BD) by a prepolymer method. Microphase-separated structure and mechanical properties of the NBDI-based PUEs were compared with general aliphatic and cycloaliphatic diisocyanate-based PUEs. The diisocyanates used were isophorone diisocyanate (IPDI), 4,4′-dicyclohexylmethane diisocyanate (HMDI) and 1,6-hexamethylene diisocyanate (HDI). Regular polyurethanes were also prepared as hard segment models from each isocyanate and BD to understand the feature of each hard segment chain. The HDI-based PUE showed the largest Young's modulus and tensile strength in the four PUEs due to the ability of crystallization of the hard segment component and the strongest microphase separation. HMDI has both properties of aliphatic and cycloaliphatic diisocyanates because of its high symmetrical chemical structure compared with NBDI and IPDI. On the other hand, the NBDI- and IPDI-based PUEs have an inclination to phase mixing, leading to decreased Young's modulus and tensile strength. The NBDI-based PUE exhibited better thermal properties at high temperatures due to stiff structure of NBDI.