双组分聚氨酯汽车风挡玻璃密封胶的研究

介绍了一种双组分聚氨酯汽车风挡玻璃密封胶,以预聚体为主要考察对象,总结了聚醚种类、增塑剂及填料所占总配方的比例对预聚体性能的影响;经优化分析选择力学性能好的预聚体用于密封胶配方的设计,测定其力学性能,测试结果参考HB/T 4363-2012Ⅰ类单组分聚氨酯密封胶技术指标进行判定。实验结果表明,所研发的双组分聚氨酯密封胶能够满足相关技术指标。     

高弹性改性聚醚密封胶的制备与密封性能研究

使用聚醚二元醇等材料实现封端,制备硅烷封端聚醚预聚体,将该预聚体作为基础制备高弹性改性聚醚密封胶。通过试验确定吸附剂用量,分析温度对密封胶弹性影响以及密封胶的固化性能。研究不同湿度下密封胶的吸水率变化,并测试密封胶的粘结性能。试验结果显示,多孔二氧化硅吸附剂能够提升硅烷封端聚醚预聚体性能;密封胶所处环境温度越高,弹性模量呈现下降趋势,弹性恢复率没有出现明显变化;周围环境湿度的增加能够提升密封胶吸水性,使得密封胶不易开裂,养护28 d的密封胶在粘结金属材料和陶瓷材料时密封效果更好,密封性能更高。     

单组分硅烷封端聚氨酯密封胶的研制

以聚醚多元醇和TD I为主要原料,合成预聚体,对预聚体用硅烷进行封端,添加白炭黑、碳酸钙等补强填料,研制了单组分湿气固化密封胶。探讨了多元醇的最佳配合比例、预聚体NCO含量以及封端剂的选择。该密封胶贮存稳定,拉伸强度>2.0 MPa,伸长率>300%。     

单组分湿固化聚氨酯密封胶预聚体的合成研究

单组分湿固化聚氨酯密封胶因性能优越应用十分广泛,其中聚氨酯密封胶预聚体的好坏直接决定聚氨酯密封胶的性能,是研制聚氨酯密封胶中非常重要的部分.介绍了单组分湿固化聚氨酯密封胶预聚体的合成工艺,确定了反应物的配比,并对反应用催化剂,反应温度,反应时间等条件进行了考察.结果表明,采用聚醚混合物与异氰酸酯的配比为4∶1,NCO的百分含量为3%～3.5%,催化剂的用量为0.1%,温度为80±2 ℃的条件下,反应4h得到的预聚体具有良好的性能.     

有机硅改性单组分聚氨酯密封胶的研制及力学性能研究

本文研究了聚氨酯密封胶的预聚体、填料、有机硅等因素对密封胶拉伸强度,伸长率、硬度等力学性能的影响。发现分子结构不同的预聚体与性质不同的填料对其力学性能的影响不同。填料炭黑的补强作用特别强。     

新型汽车密封胶用聚醚多元醇的合成及其应用

以丙二醇和甘油为混合起始剂,合成了一种新型汽车密封胶用聚醚多元醇,并与二苯基甲烷二异氰酸酯反应合成了聚氨酯预聚体密封胶,探讨了催化剂、温度等因素对聚醚多元醇及预聚体的影响。结果表明,此聚醚多元醇反应活性比传统三官能度聚醚更稳定,降低了预聚体的聚釜风险,并提高制品的拉伸强度和断裂伸长率。     

中空玻璃用单组分聚氨酯密封胶的制备及应用

以4,4′-二苯基甲烷二异氰酸酯(MDI)和聚醚多元醇制备了单组分聚氨酯预聚体。按照配方量将预聚体、填料、增塑剂、偶联剂和催化剂等物质混合,经真空搅拌得到单组分聚氨酯密封胶。单组分聚氨酯密封胶与第1道密封材料(丁基密封胶)的相容性良好。用该密封胶与底涂剂配套使用时,对玻璃和铝具有良好的粘接效果。     

纳米碳酸钙补强硅烷化聚氨酯密封胶的研究

以纳米碳酸钙填充硅烷化聚氨酯（SPU）制备密封胶，研究预聚体数均相对分子质量（Mn）、纳米碳酸钙用量、增塑剂DIDP用量及硅烷品种对密封胶性能的影响。结果表明，随着预聚体砜的增大，SPU及其密封胶的硬度和拉伸强度减小，拉断伸长率增大；随着纳米碳酸钙用量的增大，密封胶的物理性能提高；增塑剂DIDP的适宜用量为30-40份；加入γ-氨丙基三乙氧基硅烷的密封胶的粘合性能最佳。     

低模量水固化双组分聚氨酯密封胶的制备和性能

以聚醚三醇EP-330NG、聚醚二醇DL-1000D和甲苯二异氰酸酯(TDI)为主要原料制备预聚体(A组分),水、填料及其他助剂为B组分,制备了低模量双组分聚氨酯密封胶.考察了预聚体中EP-330NG和DL-1000D的摩尔比值、预聚体的NCO含量、B组分中水的用量对聚氨酯密封胶性能的影响.结果表明:当EP-330NG...     

木质素基聚氨酯密封胶的制备与表征

木质素是一种含有羟基的三维网状天然高分子,因其存在醇羟基和酚羟基,被广泛用于聚氨酯领域。采用木质素与聚醚二元醇,制备了木质素基聚氨酯密封胶。对合成的木质素基聚氨酯预聚体进行了FT-IR和TG分析,并探讨了木质素与聚醚二元醇的羟基比对预聚体性能的影响以及Ca CO3和潜固化剂对木质素基聚氨酯密封胶性能的影响。结果表明:木质素基聚氨酯密封胶预聚体中木质素与二元醇羟基物质的量比为2∶1时,拉伸强度可达2.38MPa、断裂伸长率为576%。聚氨酯密封胶中引入木质素使得聚氨酯密封胶在热分解初期热失重量较高,但后期热分解的剩余物保留率高。在木质素基聚氨酯密封胶加入不超过50%碳酸钙时,随着碳酸钙添加量的增加断裂伸长率降低,拉伸强度则随着碳酸钙添加量的增加而增加。噁唑烷类潜固化剂能够有效降低单组分湿固化聚氨酯密封胶在固化时胶层中的气泡。     

硅烷化聚氨酯及其密封胶的制备和性能研究

合成了不同结构的硅烷化聚氨酯预聚物(SilylatedPolyurethane,SPU),其中封端剂OLJ-3(仲胺类活性硅烷)封端的硅烷化聚氨酯的性能优于其他的封端剂封端的硅烷化聚氨酯;不同的NCO/OH的反应配比和不同分子质量的聚醚可以合成出不同分子质量和粘度的硅烷化聚氨酯;分子质量高,则硅烷化聚氨酯的断裂伸长率高,模量和强度低,反之,分子质量低,则硅烷化聚氨酯的断裂伸长率低,而模量和强度高。     

湿固化作用对NCO／OH型双组分聚氨酯涂料漆膜性能的贡献

NCO/OH型聚氨酯漆的固化机制是—NCO与—OH反应交联和—NCO与空气中水分反应交联的叠加。通过同一种NCO/OH聚氨酯漆的漆膜在相同温度而湿度悬殊的环境中固化过程中漆膜性能增长情况的对比,证实了湿固化对漆膜的充分固化与漆膜性能的增长有明显的贡献。     

Influence of the hard-to-soft segment ratio on the adhesion of water-borne polyurethane adhesive

Three water-borne polyurethane dispersions were synthesised by the pre-polymer mixing process. Different hard segment contents in the polyurethanes were obtained by varying the diisocyanate/macroglycol (NCO/OH) molar ratio. A decrease in the NCO/OH ratio produced an increase in the mean particle size and in the pre-polymer viscosity, as well as a decrease in the molecular weight of the polyurethane. On the other hand, the lower the NCO/OH ratio, the more crystalline the polyurethane and the lower the resistance to flow at high temperature. Lower NCO/OH ratios improved the thermal degradation stability of the polyurethane. Finally, a high initial adhesion to PVC was obtained in all joints produced with the aqueous polyurethane dispersions and the final adhesion increased as the NCO/OH ratio in the water-borne polyurethane adhesive decreased.     

Fine‐tuning the mechanical properties of hydroxyl‐terminated polybutadiene/ammonium perchlorate‐based composite solid propellants by varying the NCO/OH and triol/diol ratios

Changes in the mechanical properties of hydroxyl‐terminated polybutadiene/ammonium perchlorate‐based composite solid propellants were studied during the curing period with respect to variations in the crosslink density, which was predominantly determined by the equivalent ratio of diisocyanate to total hydroxyl (NCO/OH ratio) and the equivalent ratio of triol to diol (triol/diol ratio). For this purpose, 16 propellants were prepared in different compositions through changes in the NCO/OH ratios (0.81, 0.82, 0.83, and 0.85) for each triol/diol ratio (0.07, 0.09, 0.11, and 0.13) and were tested for their mechanical properties immediately after curing. The propellants with an NCO/OH ratio of 0.82 had minimum stress, modulus, and hardness with maximum strain capability, whereas the propellants with an NCO/OH ratio of 0.85 showed just the opposite behavior. Variations in the isocyanate level seemed to have more effect on the mechanical properties at higher triol/diol ratios. It was also concluded that the propellants with triol/diol–NCO/OH combinations of 0.11–0.83, 0.11–0.85, 0.13–0.81, 0.13–0.83, and 0.13–0.85 were not acceptable for upper stage case‐bonded rocket applications because of either high tensile strength or high modulus. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2072–2079, 2002; DOI 10.1002/app.10605     

Studies on structure property correlation of cross‐linked glycidyl azide polymer

Glycidyl azide polymer (GAP) has been evaluated for use as binder for solid propellants. The effects of various parameters like cross‐linking conditions, concentration of crosslinker, and the ratio of isocyanate to hydroxyl functional groups (NCO/OH ratio) on the mechanical properties were studied in detail. It was observed that the type of curing agent and the NCO/OH ratio have a strong influence on the gum‐stock properties. Similar impact was seen for cross‐linker concentration also. The swelling characteristics of the cross‐linked binder prepared with different NCO/OH ratios were evaluated with toluene and tetrahydrofuran (THF). The polarity and the solubility parameter of the solvents were found to influence the swelling of GAP. The NCO/OH ratio and cross‐linker concentration of the polymer were also found to affect the swelling characteristics. The sol fraction determined for the polymer was found to follow a similar pattern. The cross‐link density and average molecular weight between crosslinks (Mc) were determined from the swelling studies and also from the stress–strain relationship. The Mc values were found to be influenced by the NCO/OH ratio. Finally, the Mc values determined from the swelling data were correlated to the gum‐stock properties, and the model parameters were estimated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Hyperbranched polyurethane (HBPU)-urea and HBPU-imide coatings: Effect of chain extender and NCO/OH ratio on their properties

Effect of chain extender and NCO/OH ratio on the properties of hyperbranched polyurethane (HBPU)-urea and HBPU-imide coatings were examined. The NCO terminated pre-polymers were prepared by reacting the first (G1) and the second (G2) generation hyperbranched polyester polyols (HBP-G1 and HBP-G2) with excess diisocyanate. The excess NCO content of the prepolymer was reacted with different chain extenders viz., 3-aminopropyl triethoxysilane (APTES), pyromellitic dianhydride (PMDA) and N-hydroxyphthalimide (NHTM) to obtain HBPU-urea or HBPU-imide coatings. The structure–property relationships of the different coatings were investigated by FTIR peak deconvolution, and these data suggests the highest extent of hydrogen bonding interaction for PMDA-based coatings, which increases with increasing NCO/OH ratio. Film properties were evaluated by TGA, DMTA, UTM and contact angle measurements; these results were supported by FTIR deconvolution results. As per contact angle measurements, hydrophobicity of coatings increased by increasing NCO/OH ratio. The adhesive strength, abrasion resistance, alkali resistance, and gel content of the coatings were also evaluated.     

蓖麻油型聚氨酯胶粘剂粘合性能的研究

探讨了预聚体合成时二元醇质量分数及胶粘剂配制时—ＮＣＯ／—ＯＨ摩尔比和催化剂（有机锡类）质量分数对蓖麻油型聚氨酯胶粘剂粘合性能的影响。结果表明,预聚体合成时二元醇质量分数为０７０及胶粘剂配制时—ＮＣＯ／—ＯＨ摩尔比为１３时,催化剂质量分数为０００６～０００８和—ＮＣＯ／—ＯＨ摩尔比为１４时,催化剂质量分数为０００４～０００６,胶粘剂的粘合性能最佳;胶粘剂配制时—ＮＣＯ／—ＯＨ摩尔比增大,胶粘剂的粘合性能提高;蓖麻油型聚氨酯胶粘剂的耐水性较好     

Waterborne polyurethane dispersions obtained with polycarbonate of hexanediol intended for use as coatings

Three waterborne polyurethane dispersions derived from polycarbonate of hexanediol (PCD) with molecular weight of 1000 Da were synthesized by the acetone method and used as coatings for stainless steel plates. Different hard segments content in the polyurethanes were obtained by varying the isocyanate/macroglycol (NCO/OH) molar ratio. A decrease in the NCO/OH ratio produced an increase in the mean particle size as well as a decrease in the Brookfield viscosity of the dispersions. Furthermore, the greater the NCO/OH ratio the higher the urea and urethane hard segment content, the higher the glass transition temperature value and the higher the elastic modulus of the polyurethane was. On the other hand, the NCO/OH ratio affected the adhesion of the polyurethanes. The adhesion was evaluated by using three different procedures: T-peel strength tests of flexible PVC/waterborne polyurethane dispersion/flexible PVC joints; single lap-shear tests of aluminium/waterborne polyurethane dispersion/aluminium joints and cross-cutter adhesion test of polyurethane coatings on stainless steel pieces. Finally, several properties of the polyurethane coatings on stainless steel pieces were tested including Persoz hardness, gloss, chemical resistance and yellowness index.     

Effects of NCO/OH molar ratio on miscibility and properties of semiinterpenetrating polymer networks from polyurethane and benzyl konjac glucomannan

Semi‐interpenetrating polymer network (semi‐IPN) films with different NCO/OH molar ratios of the urethane prepolymer, coded as UB, were prepared from polyurethane (PU) and benzyl konjac glucomannan (B‐KGM) by a casting method. The effect of the NCO/OH molar ratio of the urethane prepolymer on the miscibility and properties of the UB films was investigated using Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical thermal analysis, thermogravimetric analysis, and swelling and tensile tests. The results indicated that, with an increase of the NCO/OH ratio, the crosslink density of the UB films increased, resulting in improved miscibility between PU and B‐KGM and a relatively high light transmittance of the UB films. However, the thermal stability of the UB films decreased with increase of the NCO/OH ratio of the urethane prepolymer, due to the depolymerization of the urethane bonds of the PU networks. When the NCO/OH ratio increased from 2 to 4, the tensile strength of the UB films increased from 15 to 27 MPa, while the breaking elongation decreased from 72 to 16%, resulting from the chemical and physical crosslinks, namely, the enhancement of the covalent bonds and hydrogen‐bonding networks. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1304–1310, 2003     

Kraft lignin in polyurethanes I. Mechanical properties of polyurethanes from a kraft lignin–polyether triol–polymeric MDI system

Polyurethanes with various NCO/OH ratios and kraft lignin contents were synthesized by polymerization of kraft lignin (free of the low and high molecular weight fractions), a propylene–oxide-based polyether triol and polymeric MDI in tetrahydrofuran solution. Films were made by solvent casting and tested with respect to swelling behavior and tensile properties. The main findings were: At low NCO/OH ratios, kraft lignin contributed effectively to the formation of the three dimensional network; under particular conditions of NCO/OH ratio and kraft lignin content, polyurethanes of considerable toughness were obtained; at high kraft lignin contents, the obtained polyurethanes were hard and brittle regardless of the NCO/OH ratio used.