聚氨酯弹性体的合成与耐热性能研究

分别以聚己内酯二醇(PCL)、聚四亚甲基醚二醇(PTMG)为低聚物二醇原料,以对苯二异氰酸酯(PPDI)、二苯基甲烷二异氰酸酯(MDI)或2,4-甲苯二异氰酸酯(TDI)为异氰酸酯原料,以1,4-丁二醇(BDO)或3,3'-二氯-4,4'-二氨基二苯基甲烷(MOCA)为扩链剂,采用预聚体法合成了结构不同的聚氨酯(PU)弹性体,并对其进行了物理机械性能测试、热重分析(TG)和动态力学分析(DMA)。结果表明,PCL/PPDI/BDO聚氨酯弹性体的力学性能和耐热性能最好; PPDI/BDO/PCL聚氨酯弹性体的储能模量优于TDI/MOCA/PCL弹性体;当硬段结构为PPDI/BDO时,较低温度下,PCL体系的储能模量优于PTMG体系,较高温度下,PTMG体系优于PCL体系。     

金属粘接用溶剂型封闭聚氨酯胶粘剂的制备及性能

采用二苯基甲烷-4,4'-二异氰酸酯(MDI)和聚己二酸-1,4-丁二醇酯二醇(PBA)合成了一系列的聚氨酯预聚物.以丁酮肟作为封闭剂,以异佛尔酮二胺(IPDA)和4,4'-二氨基二环己基甲烷(PACM)为扩链剂,以甲苯和乙酸乙酯混合溶液作为溶剂,制备了溶剂型封闭聚氨酯胶粘剂.对聚氨酯的合成、封闭和解封以及封闭聚氨酯固...     

TODI类浇注型聚氨酯弹性体的耐热性能研究

用3,3'-二甲基-4,4'-联苯二异氰酸酯(TODI)与聚四氢呋喃(PTMG)、聚己内酯多元醇(PCL)合成了一系列浇注型聚氨酯弹性体,考察了不同聚合物多元醇、扩链剂以及硬段含量对弹性体耐热性能和力学性能的影响.结果表明:PCL体系的耐热性能和力学性能优于PTMG体系,其拉伸强度在120℃下保有率>90%;用3,3'...     

聚氨酯弹性体软段对其力学性能的影响

先用4,4'-二苯基甲烷二异氰酸酯(MDI)与不同相对分子质量不同种类低聚物多元醇合成预聚体,再以1,4-丁二醇(BDO)为扩链剂制备聚氨酯弹性体,考察了软段对聚氨酯弹性体力学性能的影响.结果 表明:当预聚体NCO含量相同时,聚酯型聚氨酯弹性体的力学性能整体优于聚醚型的,随低聚物多元醇相对分子质量的增加,聚氨酯弹性体的...     

扩链剂对TODI型聚氨酯弹性体性能的影响研究

以3,3′-二甲基-4,4′-联苯二异氰酸酯(TODI)和聚四氢呋喃均聚醚(PTMG)合成聚氨酯预聚体,分别以1,4-丁二醇(BDO)和二胺类的3,5-二甲硫基甲苯二胺(E-300)、3,3′-二氯4,4′-二氨基二苯甲烷(MOCA)和4,4′-亚甲基双(3-氯-2,6-二乙基苯胺)(M-CDEA)为扩链剂,研究了扩链剂对聚氨酯弹性体力学性能和耐热性能的影响。结果表明:以M-CDEA为扩链剂的TODI弹性体综合力学性能最为优异;在耐热性能方面,以4种扩链剂制备的TODI型聚氨酯弹性体的顺序为MCDEA>MOCA>BDO>E-300。     

NDI/MDI质量比对PUE性能的影响

以聚己二酸乙二醇酯二醇(PEA)、1,5-萘二异氰酸酯(NDI)、二苯基甲烷二异氰酸酯(MDI)及扩链剂1,4-丁二醇为原料,采用预聚体法合成聚氨酯弹性体(PUE),研究了NDI/MDI质量比对PUE常温及高温下力学性能、热性能、动态力学性能等性能的影响。结果表明：随着NDI/MDI质量比的增大,PUE的玻璃化转变温度逐渐降低,耐热性能逐渐增强,损耗因子降低。当NDI/MDI的质量比为1/1时,PUE在常温和高温下的综合力学性能表现最好。     

1,3-丙二醇基聚酯型聚氨酯材料的合成与性能

分别采用相对分子质量为2000或3000的聚己二酸-1,3-丙二醇酯二醇,与4,4'-二苯基甲烷二异氰酸酯(MDI)反应制备NCO封端的预聚体,然后用1,4-丁二醇(BDO)扩链制备了聚氨酯材料(PU-PPA),并且与以聚己二酸-1,4-丁二醇酯二醇(PBA)所制备的聚氨酯材料(PU-PBA)进行性能对比。结果表明,聚酯型PU材料的吸水率较低;PU-PPA的软段结晶能力弱,储能模量低,柔顺性好,但其力学强度和耐水解性能差于PU-PBA材料;软段相对分子质量的增加能够提高PUPPA的微相分离程度,从而改善其力学性能,但耐水解性变差。此外,提高硬段含量能够同时提升PU-PPA的力学强度和耐水解性。     

国内外近期有关胶黏剂文献的增注题录

07-060快速固化聚氨醋热熔胶的制备及其性能[以4,4′-二苯甲烷二异氰酸酯(MDI)、甲苯二异氰酸酯(TDI)和1,4-丁二醇为硬段,聚四氢呋喃二醇(PTMG)为软段,制备了一系列快速固化的反应性聚氨酯热熔胶,考察了-NCO基团含量、异氰酸酯指数及二异氰酸酯类型对粘     

主链含酰亚胺环的耐热型聚氨酯弹性体的合成与表征

以均苯四羧酸二酐(PMDA)改性4,4'-二苯基甲烷二异氰酸酯(MDI),得到含酰亚胺环的二异氰酸酯,与未改性MDI以一定比例混合,再与聚己二酸-1,4-丁二醇酯二醇和1,4-丁二醇经两步法反应,制备了主链含有酰亚胺环的热塑性聚氨酯弹性体(IPU),并与未改性的热塑性弹性体(TPU)进行比较。采用红外光谱仪、差示扫描量热仪、热失重分析仪和拉力试验机表征和分析了聚氨酯弹性体的结构、热性能及力学性能。结果表明,PMDA成功改性MDI;IPU的耐热性能较TPU有所改善;热失重分解速率明显降低;体系微观结构发生明显变化;硬度和拉伸强度增加;断裂伸长率减小。     

阀体密封件用TPU材料合成及性能评估

以聚碳酸酯二醇(PCDL)、4,4'-二苯基甲烷二异氰酸酯(MDI)、3,3'-二甲基联苯基-4,4'-二异氰酸酯(TODI)和氢醌-双(2-羟乙基醚)(HQEE)为原料,采用预聚体法合成了两种不同二异氰酸酯类型的阀体密封件用热塑性聚氨酯弹性体(TPU)。考察了TPU的室温和高温力学性能、压缩性能、耐疲劳性能、磨耗和耐酸性介质性能。结果表明,MDI型TPU的定伸强度、拉伸强度和撕裂强度优于TODI型TPU,TODI型TPU的断裂伸长率优于MDI型TPU,TODI型TPU在80℃的力学性能明显优于MDI型TPU; TODI型TPU的承压性能、耐疲劳性和耐磨性比MDI型TPU的好;两种TPU对硫酸溶液的耐受性较好,对盐酸溶液和氢氟酸溶液有一定的耐受性,对硝酸溶液的耐受性很差。     

CPVC加工性能和冲击性能的改进

研究了加工助剂和冲击改性剂对CPVC性能的影响，试验结果表明：润滑型ACR加工助剂能有效提高CPVC的加工性能，AMS的最佳用量为1～2份，MBS（用量以8份为宜）对CPVC的增韧效果较好。     

Correlation of blown film optical properties with resin properties

The optical properties of conventional, free-radical polymerized low density polyethylene (LDPE) blown films are due essentially to surface irregularities that develop during fabrication. Past studies have shown that the extent to which these irregularities occur (and therefore optical properties) correlates well with the melt elasticity of the resin. Specifically, it has been shown that resins with higher melt elasticity result in films with poorer optical properties. However, it was recently reported that the optical properties of film blown from a Sci of three generically similar LDPE resins were found to correlate with the crystallization kinetics of the resins. Specifically, it was reported that the resins that exhibited faster crystallization rates produced films with better optical properties. This present work shows, however, that this apparent correlation is only coincidental. It has been shown that resins exhibiting faster crystallization rates do not necessarily result in films with better optical properties. On the other hand, it has been shown that resins with higher melt elasticity consistently result in films with poorer optical properties.     

Correlation between slurry properties and structures and properties of granules

Two types of granules were fabricated from a flocculated slurry (dispersant: 0.3 wt%) and a dispersed slurry (dispersant: 1.0 wt%), respectively. The slurry properties affected the packing density and morphology of the granules markedly; the granules obtained from the flocculated and dispersed slurries have spherical and dimpled shapes with densities 50.2 and 54.0%, respectively. A new crossed polarized microscopy showed a direct influence of slurry property on the packing structure of particles in the granules. The packing structure of particles affected the deformation behavior of granules; the loosely packed particles in the spherical granules make them easily deformable and the highly packed particles in the dimpled granules make them resistant against deformation.     

Dough forming properties

Although much has been learned about the gluten protein complex in the past 50 years, we still do not know why gluten proteins form a dough. We are left pointing out how gluten differs from other proteins, and offering a few tentative hypotheses. Contribution No. 955. Department of Grain Science and Industry, Kansas Agricultural Experiment Station, Manhattan, KS 66506.     

磺化乙丙橡胶离聚体的熔融流动性及力学性能

研究了不同因素包括相转移催化剂、磺化度、中和度、中和用阳离子及增塑剂等对磺化乙丙橡胶离聚体的熔融流动性及力学性能的影响。结果表明,在合适条件下可得到Ｂｒａｂｅｎｄｅｒ扭矩为３５～４０Ｎｍ、拉伸强度为２０～２８ＭＰａ、断裂伸长率为５００％～６００％、永久变形小于１０％的热塑性弹性体     

Other catalytic properties

The behavior of fresh and aged EUROCAT V₂O₅–WO₃/TiO₂ SCR catalysts in the (I) oxidative dehydrogenation of light alkanes, and conversion of (ii) propan-2-ol, (iii) NO in the presence of propene and oxygen, (iv) propane and propene and (v) chloropropane is reported to analyse possible modifications of the catalyst properties during use and give a more comprehensive general picture of its surface and reactivity properties.     

Melt flow properties,mechanical properties,thermal properties and morphology of polycarbonate/highly branched polystyrene blends

A highly branched polystyrene (HBPS) was synthesized via the copolymerization of 4‐(chloromethyl) styrene with styrene using the self‐condensing atom transfer radical polymerization method. The addition of HBPS as a melt modifier for polycarbonate (PC) was attempted. Melt flow properties, mechanical properties, thermal properties and morphology of the blends were studied. The results showed that a significant drop in the blend viscosity occurs immediately on addition of HBPS. Impact strength, tensile strength and glass transition temperature (T_g) of all the blends have not been significantly reduced compared with those of pure PC. The TGA analyses showed that an initial weight loss temperature of all the blends is above 458 °C and slightly low compared with that of pure PC, but all the blends still have excellent thermal stability. Morphological studies using SEM showed that a two‐phase morphology is characteristic of all the blends, with more or less spherical droplets of the minor HBPS phase dispersed in the continuous PC phase. Copyright © 2006 Society of Chemical Industry     

Solution properties of lignin. Thermodynamic properties and molecular weight determinations

Number-average molecular weights and the thermodynamic parameters ΔF?₁, ΔH?₁, and ΔS?₁ have been obtained for lignin in the solvents dimethylsulfoxide, dimethyl-formamide, and dioxane. Widely different molecular weights were found in the different solvents and at the different temperatures as a consequences of molecular association. Analysis of the thermodynamic parameters revealed that these quantities are dominated by the change in solvent structure accompanying the solution process. A correlation between the “goodness” of a lignin solvent and the Hildebrand solubility parameter is consequently misleading in such systems.     

新型PVC片材的力学性能和阻隔性能的研究

采用微层挤出技术制备了微层PVC片材,采用涂覆法制备了多层PVC/PVA复合片材,对其力学性能和阻隔性能进行了研究。结果表明:①多层结构有利于提高PVC/PVA复合片材的阻隔性能,涂覆PVA溶液增大了片材的拉伸强度。②微层PVC片材的分子链发生取向,沿挤出方向的拉伸强度明显高于垂直挤出方向;微层PVC片材的层数越多,取向作用越强,越有利于阻隔性能的提高。