Synthesis of cross-linked polyurethane elastomers with fluorescein linkages

The reaction of polyurethane prepolymers with fluorescein (free acid) and glycerin or castor oil-cross-linker has been performed in N,N-dimethylformamide and in such way a cross-linked elastomer material has been obtained. Polyurethane prepolymers were prepared by reaction of the poly(1,4-butane)diols (Terathane 1400) with aliphatic 1,6 hexamethylene diisocyanate. The above polymerization reactions lead to the formation of novel aromatic–aliphatic polyurethane elastomers having fluorescein moieties in the main chain. The resulting novel cross-linked polyurethanes have excellent mechanical properties, especially in the castor oil polyurethane elastomer formulations and show light-violet fluorescence property and could be used as photoactive polymers for labeling materials. These polyurethanes were characterized through IR, TGA, DSC, and mechanical analyses. Some aspects of the fluorescent emission in fluorescein-polyurethane elastomers were studied.     

聚氨酯弹性体结构与动态力学性能研究

讨论了扩链剂的结构对聚氨酯弹性体的形态结构和动态力学性能的影响。指出对于相分离严重的聚氨酯体系,在扩链剂中引入侧基会有效地降低微区尺寸,亦即改善软段和硬段之间的相容性,含脂肪环的扩链剂不但能增加体系的相容性,而且脂肪环的构象变化也会增加聚氨酯的力学损耗。     

一种基于有序硬段的可生物降解聚氨酯的制备及性能

以聚乙二醇(PEG,Mn=600、1000)为引发剂,L-丙交酯(L-LA)为单体,在辛酸亚锡存在下开环聚合合成了三嵌段预聚物聚丙交酯-聚乙二醇-聚丙交酯(PLA-PEG-PLA),然后以具有有序结构的二氨基甲酸酯基二异氰酸酯(六亚甲基二异氰酸酯-1,4-丁二醇-六亚甲基二异氰酸酯,HBH)扩链制备了一种可生物降解的脂肪族聚氨酯(PU-I、PU-II)。作为对比,以4,4’-二苯基甲烷二异氰酸酯(MDI)作为扩链剂合成了芳香族聚氨酯(PU-III)。通过核磁共振、红外光谱、超高分辨质谱、凝胶渗透色谱等对预聚物、扩链剂、聚氨酯的化学结构进行了表征。通过对PU-I、PU-II和PU-III膜热性能、力学性能和体外降解性能的对比,研究了有序硬段对聚氨酯性能的影响。结果表明,相对于PU-III,PU-I具有更好的力学性能(断裂强度21 MPa,断裂伸长率840%)和较快的体外降解(19d);随着亲水链段PEG含量的增加,PU膜(PUII)的断裂强度降低,断裂伸长率增加,同时体外降解速率变快。该类型的脂肪族聚氨酯具有降解产物无毒、合适的力学性能和降解性能,可替代传统的芳香族聚氨酯,在医疗行业中有更广泛的用途。     

有机硅烷偶联剂对水性聚氨酯材料性能的影响

以IPDI为硬段,PTMG1000为软段,TMP为交联剂,APTES为封端剂,合成了一系列硅烷偶联剂改性水性聚氨酯乳液,并制备了水性聚氨酯的固化膜.FT-IR分析表明,APTES上的一NH2 与聚铵酯的端--NCO发生反应,成功地将硅烷结构引入聚氨酯分子中.TG分析表明,APTES的改性,提高了聚氨酯热稳定性.随着w(...     

Effect of the diisocyanate and chain extenders on the properties of the cross-linked polyetherurethane elastomers

Polyurethane elastomers with potential for applications in damping bearings were synthesized with 1,6-hexamethylene diisocyanate, 4,4′-methylenebis-(phenylisocyanate), poly(1,4-butane)diols (Terathane 1400), 1,4-butane diol 1,6-hexane diol and glycerin chain extenders. The glass-transition temperatures of the materials ranged from −42 to −75 °C and were higher for polymers based on 4,4′-methylenebis-(phenylisocyanate) and with higher hard segment (HS) contents. The tensile strengths of the materials were 20–55 MPa and the tensile moduli were 30–134 MPa. These increased with increasing HS content. Interchain cross-linking improves thermal stability, which was measured by thermogravimetric analysis and differential scanning calorimetry. The structure and amount of HS used causes a significant variation in the properties of cross-linked elastomers.     

聚醚-酯嵌段共聚物提高聚氨酯弹性体水解稳定性的研究

采用双金属络合催化剂(DMC),以脂肪族己二酸系聚酯多元醇为起始剂,与环氧丙烷、环氧乙烷进行烷氧基化反应,制得聚醚酯多元醇用于聚氨酯弹性体(PUE)的合成,可得到综合性能优良的PUE材料。在相同硬段含量下,聚醚酯型PUE的力学性能接近纯聚酯型PUE,优于纯聚醚型PUE,并且其耐水解性能得到较大的提高,接近纯聚醚型PUE。     

TPU弹性体中化学交联对其形态影响的动态力学分析

研究了分别以微量的三羟甲基丙烷(TMP)和端异氰酸酯基的预聚体为交联剂的微化学交联TPU的动态力学性能的变化,分析了微量化学交联的TPU中化学交联对其形态结构的影响。结果表明,当以TMP为交联剂时,交联程度的增加会导致TPU软、硬微区相容性的增强,从而使其Tg和力学损耗值都上升;而当以端异氰酸酯基预聚体为交联剂时,交联程度的增加仅仅只会加强TPU软、硬微区间的相互联系作用,因而其Tg和力学损耗值变化不显著。     

封端型水性聚氨酯树脂的结构与性能

以聚酯多元醇、甲苯二异氰酸酯和二羟甲基丙酸为主要原料,丙烯酸单体封端,加入改性剂三羟甲基丙烷脱水蓖麻油酸酯(TMPDCO),制备出稳定的水性聚氨酯分散体。涂膜耐化学品性和凝胶含量测定说明,TMPDCO的加入增加了涂膜的交联度,提高了涂膜的耐化学品性。差示扫描量热法测试表明,加入封端剂增加了涂膜交联度,涂膜玻璃化转变温度明显提高。力学性能测试说明,聚酯作为软段的水性聚氨酯树脂较聚醚型耐水性好。X射线衍射分析说明,随着硬段规整度的增加,衍射峰中心依次向高角度偏移。红外表征说明,不同硬段合成水性聚氨酯的氨基甲酸酯键波数不同。     

Synthesis and characterization of polydioxolane polyurethane ionomer

A series of novel sodium salts of sulfonated polyurethane ionomers with polydioxolane as soft segment was successfully synthesized and their properties were characterized by means of Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and complex impedance analysis. As the ionization level increased, the compatibility of the hard segments and soft segments was improved and the glass transition region of soft segment became broader. The effects of ionization level, temperature, chemical components of soft segment on ionic conductivity of ionomers were investigated in detail. Adjusting the ionization level and incorporating PEG soft segment into the PDXL-PU ionomers, a new type of solid polymer electrolyte material with good mechanical properties and high ionic conductivity could be obtained.     

聚氨酯弹性体隔振性能分析

采用TDI和MDI通过预聚物法进行浇注型聚氨酯弹性体的合成。分析预聚物中异氰酸酯基含量和扩链剂的种类对聚氨酯弹性体力学性能的影响。浇注型聚氨酯隔振器与橡胶隔振器相比，具有更低的固有频率、更好的动态性能和更高的承载能力。疲劳试验结果表明聚氨酯隔振器具有优良的抗疲劳性能。     

硅胶模具浇注成形用聚氨酯树脂

利用二苯基甲烷二异氰酸酯(MDI)、聚醚多元醇及小分子扩链剂、交联扩链剂合成了一系列适用于快速硅胶模具浇注成形的二组分聚氨酯(PU)树脂.通过粘度测试考察了PU树脂的浇注性能,使用示差扫描量热分析(DSC)和热重分析(TGA)分析了树脂的热性能,并对其相关的力学性能进行了分析测试.结果表明,PU树脂两组分及其混合液的粘度较小,釜内寿命适中,浇注性能优良;通过调节硬段含量及混和扩链交联剂中三羟甲基丙烷(TMP)含量,使得PU树脂具有较高的力学性能和热性能,浇注成形件可在高负荷、高温下的使用.     

聚叠氮缩水甘油醚聚氨酯弹性体的低温粘弹特性

以1,4-丁二醇(BDO)为扩链剂,采用熔融预聚二步法合成了不同硬段含量的聚叠氮缩水甘油醚聚氨酯弹性体(GAPE)。运用动态热机械分析仪(DMA)研究其动态力学性能,得到GAPE的储能模量、损耗模量、损耗因子,进而运用时温叠加原理,合成频率跨越十几个数量级范围的主曲线,并计算出WLF方程的粘弹系数C1g和C2g,以及链段运动活化能、低温脆化参数。结果表明,硬段质量分数为33%的GAPE-2在-50℃储能模量达到6000MPa,而其低温脆化参数和活化能也较低,分别为55.6和271.0 kJ/mol,是一种刚性好、韧性高、脆性低的弹性体。     

低分子量HTPB聚氨酯弹性体的制备及其性能

为改善高固含量高聚物黏结炸药(PBX)和丁羟推进剂的工艺性能,以低分子量的端羟基聚丁二烯(HTPB)、异佛尔酮二异氰酸酯(IPDI)为主要原料,选用一缩二乙二醇(DEG)为扩链剂,采用二步法制备了聚氨酯弹性体。研究了催化剂用量对浆料黏度的影响,固化参数R及扩链剂用量对HTPB聚氨酯弹性体力学性能的影响。试验结果表明,当催化剂质量分数为0.004%时,适用期可达5 h;R值为1.1,DEG羟基含量占反应总羟基量的60%时,聚氨酯弹性体力学性能较好,拉伸强度达7.60 MPa,断裂伸长率达540.21%。动态力学分析(DMA)测试结果显示,低分子量HTPB聚氨酯弹性体有两个明显的玻璃化转变温度,说明样品存在明显的微相分离结构。     

熔纺氨纶的动态力学性能分析

应用动态力学分析，研究了两种自制的熔纺氨纶样品的动态模量、力学损耗、蠕变行为的温度依赖性，并与杜邦的干纺氨纶(Lycra)和日清纺的熔纺氨纶(Mobilon)产品的动态力学性能进行比较，从硬段微区结构、物理交联密度、软段玻璃化转变温度、蠕变-温度曲线等方面，探讨了熔纺和干纺氨纶在热变形性能上的差别．     

聚氨酯弹性体结构和性能的研究——Ⅰ.链延伸剂对聚醚氨酯动态力学性能的影响

以端羟基聚环氧丙烷(PPO,(?)=1000)和MDI及不同结构的小分子二醇(链延伸剂)用分步法合成了聚醚氨酯弹性体,乒对该弹性体的动态力学性能进行了测试(DDV-Ⅲ-EA)。结果表明:链延伸剂对聚氨酯弹性体的动态力学性能影响颇大,通过改变链延伸剂的结构来改变聚氨酯链中的硬段结构,会导致其硬段间作用(物理相互作用)发生很大改变。因而不同程度地拓宽其阻尼峰,选择适当结构的聚氯酯链延伸剂所合成的弹性体具有化良的阻尼性能,是一类极有前途的粘弹性阻尼材料。     

硬段微区结构与聚氨酯脲弹性体力学性能及耐热性的相关性

以聚四氢呋喃醚二醇(PTMG)为软段,甲苯二异氰酸酯(TDI)、二苯基甲烷二异氰酸酯(MDI)、混合异氰酸酯(n(TDI)∶n(MDI)=1∶1)分别为硬段,采用预聚体法合成了一系列不同硬段微区结构的聚氨酯脲弹性体,并通过红外光谱、热重分析、差示扫描量热以及力学表征等方法,研究了不同硬段微区结构与聚氨酯脲(PUU)体系内部微相分离、热稳定性及力学性能的相关性。结果表明,TDI型聚氨酯脲的NH官能团伸缩振动谱带出现在较低位置(3270cm~(-1)),MDI型NH官能团伸缩振动谱带出现在相对较高的位置(3285cm~(-1)),前者的T_g(-57.6℃)低于后者T_g(-49.5℃),而初始降解温度前者(294℃)高于后者(268℃),混合型的均位于两者之间。因此,TDI型PUU表现出较高的微相分离程度和硬段微区有序度,而MDI型微相混合程度较高、且微相混合程度有助于力学性能的改善。随着温度的升高,PUU内部氢键化NH官能团伸缩振动吸收强度逐渐减弱,谱带吸收位置由低波数向高波数移动,力学性能逐渐下降,当温度处于70℃左右时,其波数出现轻微的突越,力学性能也表现出较快的下降趋势。     

催化剂对异佛尔酮二异氰酸酯制备的脂肪族聚氨酯弹性体结构和性能的影响

采用一步法通过异佛尔酮二异氰酸酯与聚丙二醇和1,4-丁二醇反应合成了脂肪族聚氨酯（PU）弹性体。考察了催化剂的种类和含量对PU弹性体结构和性能的影响。结果表明,以辛酸亚锡为催化剂时,PU弹性体的软段相和硬段相间的相分离程度最明显且分子量最低,导致其力学性能最差;以辛酸铋为催化剂时,PU弹性体软段相和硬段相的相容性较好且...     

基于网络结构设计制备宽温域高阻尼聚氨酯弹性体

从网络结构角度出发,设计以聚乙二醇单甲醚(mPEG)与甲苯2,4-二异氰酸酯(TDI)反应所制得预聚体为悬挂链,聚酯二元醇和TDI反应制得预聚体为弹性链,超支化H201作为交联扩链剂制备无规网络结构的聚氨酯弹性体。采用动态力学分析仪、原子力显微镜以及正电子湮没寿命谱等表征其结构与性能,从自由体积、微相分离、氢键作用等结构与性能之间的关系深入探讨聚氨酯宽温域高阻尼机理。研究结果表明,随着悬挂链含量增加,R值(n(-NCO)/n(-OH))减小,聚氨酯的微相分离程度降低,相容性增加,氢键作用增强,自由体积增大,聚氨酯的有效阻尼(tanδ≥0.3)温域可达175℃(-60~115℃),为一种基于网络结构设计的新型聚氨酯阻尼材料。     

A composite approach for modeling deformation behaviors of thermoplastic polyurethane considering soft-hard domains transformation

Thermoplastic polyurethane elastomers (TPUs) are the most used engineering thermoplastics combining the properties for both elastomers and glassy materials. TPUs have good physical and mechanical properties, excellent chemical and abrasion resistances. Compared with typical thermoset rubbers, TPUs are easier to be processed and recycled. However, the deformation behaviors of TPUs are very complex due to their nonlinear, hysteresis, rate and temperature dependences, and softening properties. Therefore, development of a constitutive model with microstructure considerations is important for predicting the deformation behavior of TPUs under mechanical loading as well as during forming processes such as rolling and stretching. In this work, TPUs were taken as a two-phase material consisting of both hard and soft phases corresponding to their hard and soft domains. A new composite constitutive model for stress-strain response of TPUs was proposed taking into account the microstructure of TPUs as well as its evolution (hard to soft phase transformation) induced by deformation. Excellent agreement between model predictions and experimental results for the loading-unloading behaviors of two TPUs with different hard and soft segment contents confirmed the efficacy of our proposed composite constitutive model.     

Preparation and properties of adjacency crosslinked polyurethane---urea elastomers

Adjacency crosslinked polyurethane--urea (PUU) elastomers with different crosslinking density were prepared by using hydroxyl-terminated liquid butadiene-nitrile (HTBN), toluene diisocyanate (TDI) and chain extender 3,5-dimethyl thio-toluene diamine (DMTDA) as raw materials, dicumyl peroxide (DCP) as initiator, and N,N'-m-phenylene dimaleimide (HVA-2) as the crosslinking agent. The influences of the crosslinking density and temperature on the structure and properties of such elastomers were investigated. The crosslinking density of PUU elastomer was tested by the NMR method. It is found that when the content of HVA-2 is 1.5%, the mechanical properties of polyurethane elastomer achieve optimal performance. By testing thermal performance of PUU, compared with linear PUU, the thermal stability of the elastomers has a marked improvement. With the addition of HVA-2, the loss factor tanδ decreases. FT-IR spectral studies of PUU elastomer at various temperatures were performed. From this study, heat-resistance polyurethane could be prepared, and the properties of PUU at high temperature could be improved obviously.