聚异氰脲酸酯改性聚氨酯弹性体的RIM合成研究

通过异氰脲酯改性聚氨酯弹性体的化学组成及ＲＩＭ工艺条件的考察，确定了合知宾ＲＩＭ的化学组成和工艺条件，进而采用ＲＩＭ一步法合成了聚异氰脲酸酯改性聚氨酯弹性体，性能测试表明，在聚氨酯结构中引入改性的聚异氰脲酸酯环结构不仅能明显改善弹性体的热稳定性，而且还能显著提高弹性体的力学机械性能；并随异氰脲酸酯引入量的增加，弹性体的热稳定性和力学性能都相应提高。     

耐热型聚氨酯弹性体的合成

催化合成了甲苯二异氰酸酯的部分三聚体异氰脲酸酯,然后与聚醚二元醇反应,用二步法手工浇注成异氰脲酸酯改性的聚氨酯弹性体。用红外光谱法证实了产物中异氰脲酸酯的存在。根据用二正丁胺法测得的NCO基团的质量分数可计算出异氰脲酸酯的质量分数,用热重法分析了产物的热稳定性。结果表明,与普通聚氨酸弹性体相比,合成的改型聚氨酯弹性体的热稳定性得到了明显提高。     

聚氨酯改性聚异氰脲酸酯弹性体的合成和热性能分析

本文介绍用２，４，６－三（二甲胺基甲基）苯酚（ＤＭＰ－３０）作催化剂，采用一步法工艺制备聚氨酯改性聚异氰脲酸酯弹性体的研究工作，并用红外光谱、差热分析、热失重等方法对所制弹性体进行了定性、定量热性能分析。结果表明，通过调节催化剂用量、两组分摩尔比等工艺条件，可以使整个反应过程在１分钟之内完成，适合ＲＩＭ加工工艺；由红外光谱法和差热分析可定性确知所制材料中含有聚异氰脲酸酯三聚体和氨酯，由热失重分析可     

一种耐热型聚氨酯弹性体的合成

在三聚催化剂的作用下,合成出了异佛尔酮二异氰酸酯的三聚体异氰脲酸酯,然后使它与聚酯多元醇反应,采用两步法手工浇注合成含异氰脲酸酯环的聚氨酯弹性体。采用红外光谱对该三聚产物进行了表征,并证实了异氰脲酸酯的存在。采用六氢吡啶法测出了异氰脲酸酯的质量分数。分别采用热重法和机械性能测试分析了弹性体的热稳定性和机械性能。结果显示,与普通聚氨酯弹性体相比,用异氰酸酯改性后的聚氨酯弹性体的热稳定性明显得到了提高。     

含异氰脲酸酯基团浇注型TDI聚氨酯弹性体的合成与其耐热性能的研究

在催化剂作用下,合成了TDI-100型异氰脲酸酯,并与己二酸乙二醇丙二醇酯二醇（PEPA）合成了浇注型聚氨酯弹性体,通过不同温度下的热失重分析（TGA）和弹性体的力学性能高温保持率对比分析表明,在TDI型聚氨酯弹性体中引入异氰脲酸酯基团,可明显提高弹性体的耐热性能。     

含异氰脲酸酯基团浇注型聚氨酯弹性体的动态性能研究

在催化剂作用下,合成了TDI-100型异氰脲酸酯,并与己二酸乙二醇丙二醇酯二醇（PE—PA）合成了浇注型聚氨酯弹性体,通过动态力学性能测试表明,在TDI型聚氨酯弹性体中引入异氰脲酸酯基团后,在动态条件下,弹性体的动态性能有一定程度的下降。     

可生物降解热塑性聚氨酯弹性体的合成与性能研究

以中等分子量聚碳酸亚丙酯多元醇作为软段,并与过量的甲苯二异氰酸酯生成预聚物,用1,4–丁二醇进行扩链制备热塑性聚氨酯弹性体,整个反应体系保持—NCO/—OH=1.2。研究了硬段含量变化对材料结构与性能的影响。结果表明,所得弹性体的拉伸性能随着硬段含量的增加而增大,这是微相分离变化的结果;弹性体具有较好的生物降解性,可用于潮湿恶劣环境。     

热塑性聚氨酯弹性体熔融指数影响因素的探讨

研究了软段结构、硬段结构、合成工艺等因素对热塑性聚氨酯(TPU)弹性体熔融指数的影响。结果表明:随多元醇相对分子质量增大,熔融指数降低;相同硬度条件下,聚碳酸酯型TPU比聚己内酯型TPU熔融指数低,1,4–丁二醇扩链比对苯二酚二羟乙基醚(HQEE)扩链熔融指数低;随着异氰酸酯指数或硬段含量增加,TPU熔融指数逐渐降低;合成反应温度越高,熔融指数越低;两步法工艺比一步法工艺有更好的加工流动性。     

软段对IPDI基透明聚氨酯弹性体微相结构与性能的影响

采用不同结构的软段、扩链剂l,4-丁二醇和异佛尔酮二异氰酸酯(IPDI)为主要原料合成了透明聚氨酯弹性体。研究了软段结构变化对聚氨酯弹性体的微相结构、力学性能、热稳定性及光学透明性的影响。结果表明,相对分子质量高的软段比相对分子质量低的软段更易结晶,耐低温性能更好;与聚氧四亚甲基二醇(PTMG)相比,聚酯型聚己二酸丁二醇酯二醇(PBAG)更易结晶。结晶尺寸在纳米级,材料的透明性可达85％以上。软段含量增加对软段区的结晶影响较小,但力学性能下降明显。混合多元醇的加入进一步提高了聚氨酯弹性体的微相分离程度,有利于软段结晶,在宏观上表现为拉伸强度和弹性模量明显增加。     

聚氨酯弹性体的力学性能影响因素研究

研究了合成方法,软段及硬段组成结构,熟化条件等因素对聚氨酯弹性和学性能的影响,结果表明,聚氨酯弹性体的结构与组成,以及由此引起微相分离程度的变化,是影响弹性体性能的重要因素,不同的低聚物二醇,二异氰酸酯及扩链剂合成的弹性体性能不同,采用预聚法,以及适当熟化有助于提高弹性体的性能。     

Analysis of an injection/compression liquid composite molding process

The injection/compression liquid composite molding (LCM) process is simulated by using the control/volume finite element method (CV/FEM). The flow in the runner and the fiber-free areas is simplified by using an equivalent permeability approach. Several molding experiments were conducted using a tub-shaped mold and the structural reaction injection molding (SRIM) process for a poly(urethane/isocyanurate) matrix and a glass fiber preform. Good agreement is found between the experimental results and the simulation.     

Morphology of polyurethane–isocyanurate elastomers

The dynamic viscoelastic properties and thermal transition behavior of reaction injection molding (RIM) and cast polyurethane—isocyanurate elastomers have been studied as a function of various segments (soft and hard urethane, and hard isocyanurate) content. RIM and cast elastomers were prepared at different concentrations of soft and hard urethane, and hard isocyanurate segments. RIM elastomers with the higher isocyanate index (lower hard urethane and greater isocyanurate segment content) displayed an unchanged T_g (glass transition temperature of soft segment) and increasing T_gh (glass transition temperature of hard segment) related to the hard urethane and isocyanurate segments. This is due to the phase separation between the soft and the hard segments. Cast elastomers synthesized from the higher amount of 1,4-butanediol (greater hard urethane and less hard isocyanurate segment content) showed an increasing T_gs, decreasing T_gh of hard urethane segments, and an unchanged T_gh of isocyanurate segments. This is related to the phase mixing between the soft and the hard urethane segments and the phase separation of hard isocyanurate and hard urethane segments.     

制备方法对Ni-Mo/Al2O3加氢催化剂性能的影响

以优化制备工艺为目的,研究不同制备方法对Ni-Mo/Al₂O₃加氢催化剂性能的影响。分别采用常规负载法、“一步成型法”和“沉淀打浆法”制备了Ni-Mo/Al₂O₃加氢催化剂,以氮气吸附（BET）、X射线衍射（XRD）、程序升温脱附（NH₃-TPD）、程序升温还原（H₂-TPR）和高分辨透射电镜（HR-TEM）等表征手段对3种方法制备的催化剂进行分析,并以50mL高压加氢装置考察了催化剂的反应性能。研究结果表明,与负载法相比,采用“一步成型法”和“沉淀打浆法”制备催化剂,孔容和比表面积大幅提高,但物相形态并没有发生转变;“一步成型法”制备的催化剂酸分布呈现出强酸比例升高的趋势,金属还原性及分散度也比负载法有所下降,“沉淀打浆法”制备的催化剂则显示出较高的中强酸量比例,金属还原性与分散度亦优于负载法催化剂。对催化剂的评价结果显示,针对不同的原料,3种催化剂均具有较好的加氢脱硫、脱氮和芳烃饱和活性,但总体上“一步成型法”制备的催化剂活性较负载法有所不足,而“沉淀打浆法”制备的催化剂活性则优于负载法,评价结果与催化剂的表征分析相吻合。     

Synthesis and adsorption aspect of crosslinked PVA-based blood compatible adsorbents for LDL apheresis

Macroporous poly(vinyl acetate-co-triallyl isocyanurate) beads were prepared with suspension polymerization method. The copolymer beads were transformed into poly(vinyl alcohol-co-triallyl isocyanurate) by ester exchange reaction. Epoxy group was than connected to the surface of poly (vinyl alcohol-co-triallyl isocyanurate) by the reaction of epichlorohydrin with the hydroxyl group of the copolymer. And carboxyl groups were immobilized through 1,6-hexanediamine or triethylenetetramine space arm or directly connected to the hydroxyl group on the copolymer beads. The blood compatibility and adsorption properties for low density lipoprotein (LDL) in human plasma of the resultant macroporous crosslinked PVA-based adsorbents were investigated.     

Chemorheology of poly(urethane/isocyanurate) formation

Poly(urethane/isocyanurate) is a major resin used in the structural reaction injection molding (SRIM) process. In this study, the kinetics and viscosity changes of a poly(urethane/isocyanurate) resin were investigated by the adiabatic temperature/viscosity rise method and differential scanning calorimetry. The effect of the catalyst concentration and the volume ratio of isocyanate to polyol was investigated. It is found that isocyanate trimerization depends on the diffusion effect resulted from the urethane formation. A kinetic model including the diffusion effect is developed, which is able to predict the experimental results. The reaction induced viscosity rise depends on the concentration and the molecular weight of the formed polymer. The measured adiabatic viscosity rise correlates well with the calculated molecular weight growth using the recursive method.     

微酸环境响应的聚天冬氨酸修饰脂质体的制备与表征

利用带负电的聚天冬氨酸分子与部分带正电的磷脂双分子层之间的静电吸附作用,通过"一步法"成功制备了聚天冬氨酸(PASP)修饰脂质体(PLPs),实现了修饰脂质体微酸环境响应性。将脂质体制备与PASP修饰同时完成的"一步法"大大简化了制备工艺,提高了脂质体(PLPs)的制备效率。通过单因素筛选确定了pH敏感性显著的修饰脂质体制备条件,即外水相溶液PASP浓度2.5%(质量分数),pH8.5。透射电子显微镜照片显示PLPs由于修饰剂的存在具有更大的粒径,且表面电负性高,证明了"一步法"成功制备了pH敏感性修饰脂质体。     

一步法合成三羟甲基丙烷脂肪酸己二酸混合酯

采用红外光谱,核磁共振等分析手段研究了一步法合成三羟甲基丙烷脂肪酸己二酸混合酯,并考察了己二酸在一步法合成混合酯时的反应情况,结果表明:一步法合成三羟甲基丙烷脂肪酸己二酸混合酯酯化反应可达99.0%,己二酸在该体系中更易反应完全。并且与两步法合成的三羟甲基丙烷脂肪酸己二酸混合酯结构相近,性能相当。     

One-step fabrication of nanowire-grid polarizers using liquid-bridge-mediated nanotransfer molding

Ag nanowire-grid polarizers (NWGPs) were prepared by a one-step fabrication method, called liquid-bridge-mediated nanotransfer molding (LB-nTM). LB-nTM is a new direct nano-patterning method based on the direct transfer of various materials from a mold to a substrate via liquid layer. We fabricated NWGPs with Ag nanowire arrays (81 nm parallel lines and 119 nm spaces) on 2.5 in. transparent substrates by LB-nTM using an Ag nanoparticle solution. The maximum and minimum transmittances of the Ag NWGP at 800 nm were 80% and 10%, respectively.