聚醚型聚氨酯预聚体增韧单体浇注尼龙性能研究

由聚丙二醇与甲苯二异氰酸酯(TDI–80)反应,合成聚氨酯预聚体,以此预聚体活化己内酰胺单体,在催化剂Na OH作用下,引发己内酰胺单体聚合,制得预聚体增韧单体浇注尼龙(MCPA6)嵌段共聚物。改变预聚体添加量,可制得不同性能的嵌段共聚物。研究发现,随预聚体添加量的增加,嵌段共聚物材料的断裂伸长率升高,拉伸强度、硬度下降,而密度几乎无变化,表明预聚体对单体浇注尼龙增韧效果明显。     

PAMMO基热塑性弹性体的合成及表征

以聚3–叠氮甲基–3–甲基氧杂环丁烷(PAMMO)为软段,2,4–甲苯二异氰酸酯和1,4–丁二醇为硬段,1,2–二氯乙烷为溶剂,采用溶液聚合一步法合成了含叠氮基热塑性弹性体(ATPE)。通过IR、GPC、DSC、力学性能测试等手段对ATPE的结构和性能进行了表征。结果表明:所合成的ATPE具有典型的叠氮聚醚聚氨酯特征;当R值为0.98,硬段质量分数为40%~45%时,聚合物的力学性能较优;ATPE的数均相对分子质量为50 000左右,玻璃化转变温度为–21.26℃,分解峰温为260.2℃。     

聚氨酯/无纺布复合抛光垫的微结构控制及透水性能改进

化学机械抛光中,抛光垫的材料特性是影响抛光效率和光亮度的重要因素之一。聚氨酯抛光垫通常由聚氨酯和无纺布复合制备而成。具有微结构可调性能的聚氨酯抛光垫由改进后的两步法制得,无纺布浸渍聚氨酯浆料后,部分溶剂在水浴中去除,然后在烘箱中去除剩余溶剂。改进后工艺的预凝聚温度、预凝聚时间、浆料浓度等参数获得了优化,并研究了其对抛光垫结构、性能的影响。改进后的方法使聚氨酯与无纺布纤维紧密结合,既保证了纤维之间孔隙的存在,又增加了材料的强度,在不损失材料硬度的前提下,显著提高了产品的透水性,并有利于打磨效率的提高。与此同时,该方法可以有效减少有机溶剂的使用,大幅缩减生产成本,具有节能、环保的特点。     

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。     

不同软段结构对PUR–T性能影响研究

采用4,4′–二苯基甲烷二异氰酸酯为硬段,聚ε–己内酯、聚四氢呋喃醚二醇、聚乙二醇为软段,1,4–丁二醇为扩链剂合成了不同软段结构的热塑性聚氨酯弹性体(PUR–T),并用傅立叶变换红外光谱仪对其结构进行了表征,讨论了不同软段结构、不同软段分子量、不同软段浓度等因素对PUR–T力学性能和热性能的影响。结果表明,合成的PUR–T即为本研究的目标产物;PUR–T软段分子量越小其力学性能越优异,但对其热稳定性影响不大;软段结构对PUR–T的性能影响显著,其中聚酯型PUR–T的力学性能优于聚醚型PUR–T,但热稳定性较聚醚型PUR–T差;随着软段浓度的增加,PUR–T的拉伸强度和撕裂强度都呈先提高后降低的趋势,当软段浓度为60%时达到最高,PUR–T的热稳定性随软段浓度的增加而升高。     

邻接交联型聚氨酯弹性体的制备与性能

以聚四氢呋喃醚二醇(PTMG)、端羟基聚丁二烯-丙烯腈(HTBN)和交联剂N,N-间苯撑双马来酰亚胺(HVA-2)作为共混软段,甲苯二异氰酸酯(TDI)为硬段,3,5-二甲硫基甲苯二胺(DMTDA)为扩链剂制备出邻接交联型聚氨酯脲(PUU),研究了硬段含量、交联密度和温度对其力学性能的影响,深入探讨了交联密度对材料热稳定性和低温热性能的影响。采用平衡溶胀法、高低温力学测试、热失重分析法(TGA)、差示扫描量热分析法(DSC)等测试手段对材料的交联密度、力学性能以及热性能进行分析表征。结果表明,当硬段质量分数为39%时,制备的线型PUU力学性能最好;HVA-2的加入增加了PUU的交联密度,提高了材料的热性能和力学性能。当交联密度为0.947×10-3 mol/cm3时,交联型PUU比线型PUU的拉伸强度提高了17.3%,最大分解温度提高了20.1℃,玻璃化转变温度(Tg)增加了5℃。     

形状记忆聚氨酯的结构与性能研究

以2,4 甲苯二异氰酸酯(2,4 TDI),不同分子量的聚己二酸丁二醇酯(PBAG)和1,4 丁二醇(BDO)为原料合成了具有形状记忆功能的聚氨酯材料。通过DSC、弯曲实验和力学实验研究了形状记忆聚氨酯的性能,发现软段高度结晶和硬段聚集形成硬段微区是其具有较好形状记忆性能的必要条件。     

用混合扩链剂合成的聚氨酯弹性体

研究了混合扩链剂对MDI体系浇注型聚氨酯弹性体的工艺性能及其物理性能的影响。同时考察了不同软段、硬段结构对其性能的影响，通过TGA分析对其热性能进行了表征。     

TDI与DMTDA为硬链段的浇注型PU弹性体的合成与性能研究

采用2,4-甲苯二异氰酸酯(TDI)和3,5-二甲硫基甲苯二胺(DMTDA)为硬段单体,与不同结构的软段(聚酯、聚醚)缩聚制备了浇注聚氨酯弹性体.研究了软段结构变化对聚氨酯弹性体的力学性能、耐湿、热性能、磨耗、耐溶剂性以及动态性能的影响.结果表明,PCL弹性体能够表现出PEA型弹性体的优良抗撕裂和应力-应变行为,同时又有类似PTMG型弹性体的突出压缩永久变形和回弹性能,而且具有较好的抗湿滑性能和良好的动态使用性能,其综合性能更加平衡.     

EP/氧化石墨烯–硬脂酸丁酯微胶囊复合材料

采用种子微悬浮聚合法制备了聚苯乙烯/氧化石墨烯复合囊壁包覆硬脂酸丁酯微胶囊润滑材料(MGO–Micro LMs),以MGO–Micro LMs为润滑填料,环氧树脂(EP)为基体材料,采用浇注成型工艺制备了EP/MGO–Micro LMs复合材料。采用滑动摩擦磨损试验仪评价了MGO–Micro LMs对EP基体材料摩擦学性能的影响;采用扫描电子显微镜对磨损面的微观形貌进行表征,并探究了其磨损机理。结果表明,MGO–Micro LMs能够显著地降低EP的摩擦系数和磨损量,当MGO–Micro LMs质量分数为20%时,EP/MGO–Micro LMs复合材料的摩擦系数为0.138 44,磨损量减少了约42.3%,磨损机理主要为磨粒磨损。     

The role of diisocyanate structure on microphase separation of solution polymerized polyureas

Three diisocyanates with different symmetry and planarity (2,6-TDI, 2,4-TDI and MDI) were used to synthesize polyureas with the same oligomeric polyetheramine having a molecular weight of ∼1000 g/mol. The influence of diisocyanate symmetry on the phase separated morphology, hydrogen bonding behavior, and molecular dynamics were investigated. Symmetric diisocyanate structures facilitated self-assembly of hard segments into ribbon-like domains, driven by strong bidentate hydrogen bonding. The hard domains for the 2,6-TDI polymer appear to be continuous in AFM images, while the persistence length of the hard domains in the 2,4-TDI and MDI polymers gradually decrease, and fewer hard domains are apparent with decreasing hard segment symmetry. The extent of hard/soft segment demixing, assessed from small-angle X-ray scattering, was very incomplete for all of the polyureas and is significantly influenced by hard segment structure. For the 2,4- and 2,6-TDI polyureas, two segmental relaxations were observed using dielectric relaxation spectroscopy; one arising from relatively unrestricted motion in the soft segment rich phase, and a slower process associated with segments in the soft phase constrained by their attachment to hard domains.     

低模量聚酯型PU弹性体力学性能的研究

以聚楷酯二醇、甲苯二异氰酸酯（TDI）和扩链剂为原料,制备浇注型PU弹性体,研究了预聚法和一步法、聚酯与聚醚、80/20-TDI和2,4-TDI、聚酯二醇的种类及其相对分子质量、弹性体交联点相对分子质量和硬段质量分数对弹性体力学性能的影响。结果表明,采用预聚法,以聚酯和80/20-TDI为原料合成的PU弹性体的综合性能较好。3种聚酯型PU弹性体中,聚丁二醇己二酸酯二醇的PU弹性体的综合力学性能最好。交联点相对分子质量为4500时,PU弹性体的强度为最大值。     

溶液法合成形状记忆聚氨酯及其性能

以不同分子量的聚己二酸丁二醇酯(PBAG)为软段,2,4-甲苯二异氰酸酯(2,4-TDI)和1,4-丁二醇(1,4-BDO)为硬段,采用溶液聚合的方法合成具有形状记忆性能的聚氨酯,研究其形状记忆性能,并且用DSC分析不同的硬段含量聚合物的热行为.结果表明:以相对分子质量为3 000或以上的PBAG为软段,制得聚氨酯软段结晶,而且软段的结晶程度影响材料的形状记忆特性,软段的分子量越大,其形状记忆性能越好.     

Self-assembly preparation of popcorn-like colloidal silica and its application on chemical mechanical polishing of zirconia ceramic

Traditional mobile phone backplane materials are difficult to meet the requirements of the 5G era, and zirconia ceramic is one of the most promising backplane materials. However, its precision machining is difficult due to the hard and brittle nature. In this work, a novel popcorn-like colloidal silica was prepared by the self-assembly growth of nanoparticles for chemical mechanical polishing of the yttria-stabilized tetragonal zirconia ceramic sheets. The surface of the popcorn-like colloidal silica particles has a noticeably uneven shape, and the particle size distribution is uniform. The chemical mechanical polishing results show that the material removal rate of the prepared popcorn-like colloidal silica is increased by about 50% compared with the spherical colloidal silica, and the surface morphology is also obtained improvement. In the process of chemical mechanical polishing, the particles form multi-point contact with the ceramic sheet, resulting in an increase in the coefficient of friction, which is beneficial to the tribochemical reaction. In addition, multi-point contact can distribute the load, make the indentation shallower, and help reduce mechanical scratches. In general, the expected results are expected to provide experimental basis for the optimization of the structure of chemical mechanical polishing abrasive particles.     

TODI型热塑性聚氨酯弹性体的制备与性能研究

简单介绍了TODI型热塑性聚氨酯弹性体(TPU)的合成工艺、软段种类、硬段含量、R值等对其性能的影响,并与MDI型TPU的动态力学性能作对比.结果表明,使用预聚体法工艺制备的聚ε-己内酯(PCL)型TPU具有良好性能,硬段含量和R值在一定范围内的提高可提高材料的力学性能,与MDI型TPU相比,高温下TODI型TPU储能...     

Effect of processing method on cellulose nanocrystal/polyethylene-co-vinyl alcohol composites

Cellulose nanocrystals (CNCs) have emerged as fillers of interest to the polymer nanocomposite community due to their inherent properties and renewable precursors. However, challenges persist to incorporate CNCs into polymer matrices due to component incompatibility and/or thermal stability limitations of the nanoparticles. Therefore, the objective of this research is to examine the efficacy of different processing methods in producing CNC/polymer composites. In this work, CNCs were incorporated into polyethylene-co-vinyl alcohol (EVOH) using either a solution casting method or a multi-step method involving the same solution casting method followed by a melt mixing step. The resulting neat EVOH and composite materials were characterized to understand how the viscoelastic character and mechanical properties were influenced by CNC loading and processing method. The results of characterization experiments and micromechanical modeling suggested that the nanoparticle networks produced by each method were different and that a combined solution-melt processing method is beneficial in producing composites with improved properties, particularly at higher CNC loadings. This processing strategy may be more broadly applied to other nanocomposites.     

PPDI型热塑性聚氨酯弹性体的制备与性能研究

以对苯二异氰酸酯(PPDI)、低聚物二元醇和1,4-丁二醇为原料合成PPDI型热塑性聚氨酯弹性体(TPU),考察了软段种类和相对分子质量、硬段含量、R值(n(NCO)∶n(OH))等对其性能的影响,并与MDI型TPU的动态力学性能作比较.结果表明,聚ε-己内酯(PCL)体系TPU具有良好的性能,硬段含量和R值的提高均可...     

形状记忆聚氨酯的结构与性能研究

以2，4-甲苯二异氰酸酯、不同相对分子质量的聚己二酸丁二醇酯(PBAG)和1，4-丁二醇为原料合成了一系列聚酯型聚氨酯弹性体。发现由相对分子质量为3000和5000的PBAG所合成的聚氨酯弹性体具有良好的形状记忆功能。通过DSC、弯曲试验和力学性能测试研究了形状记忆聚氨酯的性能，发现软段高度结晶和硬段聚集形成硬段微区是使聚氨酯具有较好形状记忆功能的必要条件。     

改性聚硅氧烷/聚氨酯弹性体的阻尼性能研究

将异氰酸酯硬段引入聚硅氧烷(PDMS)链中合成改性聚硅氧烷(M-PDMS),采用不同相对分子质量的聚乙二醇(PEG)和2,4-甲苯二异氰酸酯(TDI)合成聚氨酯预聚体(PUP),通过交联聚合进行网络互穿,制备了改性聚硅氧烷/聚氨酯弹性体(M-PDMS/PUE).讨论了PEG相对分子质量、M-PDMS/PUP质量比对材料...