Effect of formulation on properties and morphology of polyurethane elastomers

A model polyurethane elastomers system has been used to study the relationships between chemical formulation, polymer physical structure and mechanical properties. The elastomers were made from formulations comprising a polyether polyol blend (diol plus triol), a chain extender blend (1,4 butane diol plus 1,1,1-trimethylol propane) and 4,4′-di-isocyanate diphenylmethane. The morphologies of the elastomers were investigated in detail, mainly by means of small angle X-ray scattering techniques. It was confirmed that the polyurethane systems examined comprised domains 50 to 100 Å in size and spaced around 100 to 200 Å apart. A complete decription of the polyurethane morphology has been made in terms of the volume fraction of domains present, the average domain size and the average domain–domain separation. The results suggest that, whilst it is possible to correlate, in general, formulation changes with variations in the elastomer morphology, it seems that direct correlations between physical structure and mechanical properties are not very meaningful in the present model system. However, it is clear that knowledge of the morphology is of considerable importance in interpreting the effects of formulation on observed properties.     

含液晶基元聚氨酯对普通聚氨酯性能的影响

合成了一类既含有刚性液晶基元又含有柔性链段的主链型含液晶基元聚氨酯(LCPU)，以端羟基四氢呋喃-环氧乙烷共聚醚为基体材料，多异氰酸酯N-100为固化剂，探讨这类含液晶基元聚氨酯对聚氨酯弹性体力学性能的影响。结果表明，5种含液晶基元聚氨酯随着柔性链段长度的变化和在聚氨酯弹性体中加入比例的变化。表现出对聚氨酯弹性体力学性能的影响有较大的差异。与未改性聚氨酯弹性体相比，改性后聚氨酯弹性体共混物垃伸强座量大提高71％倍．断裂伸长率最大提高8．7倍．     

The effect of average soft segment length on morphology and properties of a series of polyurethane elastomers. I. Characterization of the series

A series of eight thermoplastic polyurethane elastomers were synthesized from 4,4′-methylene diphenyl diisocyanate (MDI) and 1,4-butanediol (BDO) chain extender, with poly(hexamethylene oxide) (PHMO) macrodiol soft segments. The soft segment molecular weights employed ranged from 433 g/mol to 1180 g/mol. All materials contained 60% (w/w) of the soft segment macrodiol. Differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), wide angle x-ray diffraction (WAXD), and small angle x-ray scattering (SAXS) techniques were employed to characterize morphology. Tensile and Shore hardness tests were also performed. Materials were tested in the annealed state. It was found that an increase in segment length was accompanied by an increase in the degree of microphase separation, average interdomain spacing, hard domain order, hardness, stiffness, and opacity. DSC experiments showed the existence of several hard segment melting regions that were postulated to result from the disordering or melting of various hard segment length populations. For the system and composition ratio employed, it was found that optimum tensile properties (UTS and breaking strain) were achieved when a PHMO molecular weight of between 650 and 850 was utilized. © 1996 John Wiley & Sons, Inc.     

软段结构对聚氨酯弹性体性能的影响

分别以聚四氢呋喃二醇(PTMG)、聚己内酯二醇(PCL)、高顺式端羟基聚丁二烯(HTPB)和自由基聚合制得的端羟基聚丁二烯(FHTPB)为软段,采用溶液聚合两步法制得了四种聚氨酯弹性体(PUE)。通过拉伸试验、动态力学性能分析(DMA)、差示扫描量热(DSC)和热重分析等手段,考察了软段结构对它们室温及低温下力学性能、热性能等的影响。结果表明,四种PUE低温(-30℃)下的拉伸强度和断裂伸长率均大于室温下的对应值。这不仅与低温下软段诱导结晶所产生的自增强效应有关,也与软、硬两段的微相分离程度增大有关。相较于其他三种PUE,HTPB-PUE软段不仅玻璃化温度(T _g)最低,而且极性也最弱,因而微相分离程度高,具有优异的柔性,-30℃下其断裂伸长率仍达660%以上。PCL-PUE和PTMG-PUE因软段易结晶,且软段与硬段的微相分离程度低,则刚性强。低温循环拉伸试验表明,-30℃下HTPB-PUE和FHTPB-PUE有较强的弹性恢复能力,而PCL-PUE和PTMG-PUE则相对较差。DSC和DMA结果显示HTPB-PUE的T _g远低于其他三种PUE,其T _g(DSC)低至-103℃。此外,四种PUE的初始分解温度十分相近,均在270℃左右。     

The effect of average soft segment length on morphology and properties of a series of polyurethane elastomers. II. SAXS-DSC annealing study

A series of eight thermoplastic polyurethane elastomers were synthesized from 4,4′-methylene diphenyl diisocyanate (MDI) and 1,4-butanediol (BDO) chain extender, with poly(hexamethylene oxide) (PHMO) macrodiol soft segments. The PHMO molecular weights employed ranged from 433 g/mol to 1180 g/mol. All materials contained 60% (w/w) of the macrodiol. The materials were characterized by differential scanning calorimetry (DSC) following up to nine different thermal treatments. In addition, three of the materials were selected for characterization by small-angle x-ray scattering (SAXS) following similar thermal treatments. The DSC experiments showed the existence of five hard segment melting regions (labelled T1-T5), which were postulated to result from the disordering or melting of sequences containing one to five MDI-derived units, respectively. Evidence for urethane linkage dissociation and reassociation during annealing at temperatures above 150°C is presented. This process aids in the formation of higher melting structures. Annealing temperatures of 80–100°C provided the maximum SAXS scattering intensity values. Materials containing longer soft segments (and, therefore, longer hard segments) were observed to develop and sustain higher melting hard domain structures and also develop maximum average interdomain spacing values at higher annealing temperatures. Another additional series of three PHMO-based polyurethanes having narrower hard segment length distributions, was synthesized and characterized by DSC in the as-synthesized and annealed states. The resulting DSC endotherms provided further evidence to suggest that the T1-T5 endotherms were possibly due to melting of various hard segment length populations. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 803–817, 1997     

Application of NMR cross-polarization/modulus correlations to a series of polyurethane elastomers

A structure/property relationship is developed between the dynamic storage modulus, E′, and the cross-polarization time constant T_CH for a series of polyurethane elastomers. The correlations made are based on the standard linear solids model (SLSM) and on the concept that T_CH is modulated by near static molecular motions. The use of the SLSM to describe the main viscoelastic range of these polyurethanes is contrasted to previous models used to develop similar correlations. © 1994 John Wiley & Sons, Inc.     

乙二醇对聚氨酯微孔弹性体工艺及性能的影响

聚氨酯微孔弹性体,由高活性聚醚多元醇、多异氰酸酯、醇类扩链剂、催化剂等高速混合,一次浇注成型,考察乙二醇用量对聚氨酯微孔弹性体工艺及性能的影响。结果表明,随着扩链剂乙二醇量的增加,聚合反应体系乳白时间和凝胶时间逐渐缩短,聚氨酯微孔弹性体材料密度略有增加,拉伸强度和硬度明显提高,断裂伸长率明显下降。     

异氰酸酯类型对热塑性聚氨酯弹性体性能的影响

分别以5种异氰酸酯为硬段,聚己二酸1,4-丁二醇酯二醇(PBA)为软段,制备了不同异氰酸酯型的热塑性聚氨酯弹性体(TPU)。通过傅里叶变换红外光谱(FTIR),差示扫描量热(DSC)和电子拉伸等测试对其结构和性能进行表征,探究了异氰酸酯类型对热塑性聚氨酯弹性体的软硬段相互作用、PBA结晶性和机械性能的影响。结果表明,HDI-TPU氨基氢键化程度最高,HMDI-TPU的硬段间氢键化程度、软段结晶度最高,IPDI-TPU的氢键化程度、软段结晶度最低。在制备的5种异氰酸酯型TPU中,HDI-TPU的拉伸强度为29.47 MPa,断裂伸长率874%,邵D硬度44,综合机械性能最佳。     

异氰酸酯类型对热塑性聚氨酯弹性体性能的影响

分别以5种异氰酸酯为硬段,聚己二酸1,4-丁二醇酯二醇(PBA)为软段,制备了不同异氰酸酯型的热塑性聚氨酯弹性体(TPU)。通过傅里叶变换红外光谱(FTIR),差示扫描量热(DSC)和电子拉伸等测试对其结构和性能进行表征,探究了异氰酸酯类型对热塑性聚氨酯弹性体的软硬段相互作用、PBA结晶性和机械性能的影响。结果表明,HDI-TPU氨基氢键化程度最高,HMDI-TPU的硬段间氢键化程度、软段结晶度最高,IPDI-TPU的氢键化程度、软段结晶度最低。在制备的5种异氰酸酯型TPU中,HDI-TPU的拉伸强度为29.47 MPa,断裂伸长率874%,邵D硬度44,综合机械性能最佳。     

HTBN／PTMG基聚氨酯脲弹性体的结构与性能

以端羟基丁腈液体橡胶（HTBN）和聚四氢呋喃醚二醇（PTMG）共混软段并加入交联剂,制备一系列聚氨酯弹性体（PUU）,对其力学性能进行测定,并采用差示扫描量热分析（DSC）和热失重分析（TG）对材料进行热力学分析。结果表明,HTBN与PTMG以8：2的质量比共混时,制得的PUU的拉伸强度为25MPa,耐热性能也较优越;用三羟甲基丙烷（TMP）为交联剂制得交联网络结构的PUU,力学性能和热性能都有所提高;2,5-二甲基-2,5-双（叔丁过氧基）己烷（简称双二五）打开HTBN主链上的双键,进一步加强了聚氨酯的交联,使其力学及耐热性能进一步提高。     

Effect of pyridazine content and crosslinker structure on the properties of polyurethane elastomers

This article studies the development of a series of heterocyclic polyurethanes (PUs) with various pyridazine content and different crosslinker structure in their main chains. All of the isocyanate‐terminated PU prepolymers were prepared from poly(tetramethylene oxide) glycol of molecular weight 1400 (Terathane 1400) and 1,6‐hexamethylene diisocyanate. The properties of the obtained linear and crosslinked pyridazine‐based PU were compared with the properties of common PUs obtained by chain extension with 1,4‐butanediol. All the obtained PUs were characterized through spectral and thermal behavior. The pyridazine‐based PU showed improved thermal stability with 10% weight loss at temperatures above 370–400°C. With the increase of pyridazine content the values of Young's modulus are higher and the strain at break decreases. Increasing pyridazine content leads to increased films surface hydrophilicity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

三（2-羟乙基）异氰脲酸酯改性TDI-80对PUE性能的影响

用三（2-羟乙基）异氰脲酸酯（THEIC,赛克）和TDI-80反应,得到改性异氰酸酯,从而把异氰脲酸酯（IS）环引入到聚氨酯弹性体（PUE）的分子主链。通过改变赛克的用量,考察其对PUE的力学性能和耐热性能的影响。力学性能测试结果表明：当赛克质量分数为10％时,PUE的拉伸强度和拉断伸长率达到了最高值,分别为46MPa和732％。DSC和TG测试结果表明：引入IS环后,PUE的耐热性能有所提高。DMA测试结果表明：改性PUE的内耗峰比未改性的宽,并且内耗峰值所对应的温度提高（由10℃提高到60℃）。     

高性能浇注型聚氨酯弹性体的耐热性能

用不同结构的多元醇和二异氰酸酯合成了一系列浇注型聚氨酯弹性体(PU),研究了PU的物理机械性能、耐热性和动态力学性能.结果表明,当二异氰酸酯选为对苯二异氰酸酯(PPDI)、扩链剂为1,4-丁二醇(BD)时,不同结构的多元醇制备PU的耐热性从优到劣依次为聚己内酯二醇体系,聚己二酸1,4-丁二醇酯体系,聚碳酸酯二醇(PCD)体系,聚四亚甲基醚二醇体系;当多元醇选取PCD、扩链剂为BD时,不同结构的二异氰酸酯制备PU的耐热性从优到劣依次为1,5-萘二异氰酸酯(NDI)体系,对苯二异氰酸酯(PPDI)体系,3,3'-二甲基联苯-4,4'-二异氰酸酯(TODI)体系,4,4'-二苯基甲烷二异氰酸酯(MDI)体系;TODI、NDI制备PU的动态力学性能优于PPDI和MDI制备的PU.     

Synthesis and properties of liquid crystalline polyurethane elastomers

Novel type of mesogenic chain extenders used in this study are N,N′‐bis(4‐hydroxyphenyl)‐3,4,3′,4′‐biphenyldicarboxyimide (BPDI) and N,N′‐bis[4‐(6‐hydroxyhexyloxy) phenyl]‐3,4,3′,4′‐biphenyldicarboxyimide (BHDI). BHDI has a flexible spacer of 6‐methylene units but BPDI does not. The liquid crystalline polyurethane elastomers were synthesized from BPDI or BHDI as a mesogenic chain extender, 4,4′‐diphenylmethane diisocyanate, and poly(oxytetramethylene)glycol (MW 1000) as a soft segment. Polyurethane based on BHDI exhibited two melting transitions. However, any melting behavior was not shown in the BPDI‐based polyurethanes because of higher melting temperature than decomposition temperature. The composition of polyurethanes was varied as a means of manipulating liquid crystalline behavior and physical properties. The BHDI‐based polyurethanes containing above 50 wt % of hard segment content exhibited nematic liquid crystal behaviors. As the hard segment content of the BHDI‐based polyurethanes increased, the glass transition temperature (T_g), strength, modulus, and the amount of hydrogen bonding increased. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 577–585, 2000     

聚氨酯弹性体结构对阻尼性能及力学性能的影响

以不同相对分子质量的聚氧化丙烯二醇(PPG)为软段,不同异构体的二苯基甲烷二异氰酸酯(MDI)、甲苯二异氰酸酯(TDI),以及扩链剂新戊二醇(NPG)、三羟甲基丙烷(TMP)、1,4-丁二醇(BDO)为硬段,采用预聚法合成了聚氨酯弹性体,并对其损耗因子(tanδ)与力学性能进行了测试。结果表明:随着4,4’-MDI含量的增加,聚氨酯弹性体的tanδ曲线峰高降低,即阻尼性能下降,力学性能提高;随着2,4-TDI含量的增加,阻尼性能提高,力学性能降低;扩链剂TMP含量增加,tanδ峰向高温方向移动;扩链剂NPG含量增加,阻尼性能提高;软段相对分子质量增大,tanδ峰向低温移动,PPG相对分子质量从400增加到2 000时,tanδ峰的位置从80℃变化到-20℃左右。     

The effect of crosslinking on properties of polyurethane elastomers

A series of segmented polyurethanes from two polyols, 4,4′-diphenylmethane diisocyanate (MDI) and butane diol was synthesized. The degree of chemical crosslinking was controlled by varying the ratio of poly(oxypropylene) diol to poly(oxypropylene/oxyethylene) triol. The samples were prepared at the stoichiometric ratio of NCO to OH groups and at a constant concentration of hard segments (butane diol; MDI) equal 50 wt %. At low concentrations of the triol the molecular weight of the polyurethanes increases; at higher concentrations (above 9 mol %) crosslinked products are obtained. All samples show a distinct two-phase structure and in the region of 0–150°C the dynamic mechanical behavior is affected by the hard phase. Chemical crosslinking was found to increase the tensile strength and strain at break, but did not affect appreciably the tear strength, hardness, and soft segment glass transition. The stress relaxation rate at room temperature was found to depend both on the elongation and on the degree of crosslinking. A comparison of the sol fractions w_s found for crosslinked samples with the predictions of the theory of branching processes proved that the achieved conversions of reactive groups in networks are high (～ 0.98).     

Effect of the molecular structure of polyurethane elastomers on the thermomechanical properties of PUE/PC blends

Polyurethane elastomers (PUEs) based on 4,4′‐diphenylmethane diisocyanate (MDI), 1,4‐butanediol (BDO) and two kinds of aliphatic polycaprolactone (PCL) diols with molecular weight of 1000 Da and 2000 Da have been synthesized and melt‐blended with polycarbonate (PC). The compatibility of PC and PUEs was investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The results indicated that the glass transition temperature (T_g) of PC decreased by 0–40°C when 0–10 wt % of PUEs incorporated into the PC matrix. Phase separation in the blends was not detected by means of DSC characterization, but measurements of DMA and SEM indicated that phase separation existed in the blends of PC and PUEs synthesized with 1000 Da PCL‐diol. As for PUEs/PC blend in which 2000 Da PCL‐diol as PUEs' soft segments, it turned from completely compatible to partially when the NCO/OH ratio for the PUEs prepolymer was increased from 2 : 1 to 4 : 1. The compatibilities of PC and PUEs were greatly influenced by the molecular weight of polyols and the ratio of NCO/OH in the PUE prepolymer, higher molecular weight of polyols and lower NCO/OH ratio resulted in better compatibility. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

热塑性聚氨酯/氯化聚乙烯共混物形态与性能的影响因素

采用机械共混法制备了热塑性聚氯酯(TPU)/氯化聚乙烯(CPE)共混物,考察了共混比(质量比,下同)对共混物加工性能、力学性能及微观形态的影响.研究了热稳定剂种类对共混物力学性能、热稳定性的影响.结果表明.加入CPE可以明显改善TPU的加工性能;在TPU与CPE的共混比分别为70/30和60/40时,TPU/CPE共混物具有较好的力学性能;TPU与CPE共混,二者的相容性较好,热稳定性均得到提高;自制环保型钙锌复合稳定剂的综合稳定作用较好,且所得共混物的力学性能也好.     

Correlations involving modulae and cross-polarization time constants for a series of polyurethane elastomers

Correlations between the macroscopic bulk polymer properties storage modulus (E′) and loss modulus (E″) and the microscopic property of cross-polarization as represented by the time constant T_CH have been established for a series of polyurethane elastomers. The dependence of E′, E″, and T_CH as a function of molecular weight, rigid domain concentration, and temperature are graphically presented as a series of log plots. An experimental relationship is presented that shows that the distribution of motions of the flexible domains appears to be the major factor in the success of these correlations.     

HDI/IPDI对水性聚氨酯及胶膜性能的影响

采用预聚体分散法制备了一系列固含量为50%的水性聚氨酯(WPU),并通过傅里叶红外光谱(FT-IR)、粒径分析仪、X射线衍射(XRD)、差示扫描量热分析(DSC)、拉力试验机等仪器进行表征,研究了HDI/IPDI摩尔比对WPU的乳液性能和胶膜结晶性能、力学性能、耐水性能,以及基材EVA/PVC粘接性能的影响,分析了不同摩尔比的HDI/IPDI和粘接时间与WPU胶黏剂对EVA/PVC粘接性能的关系。研究发现,随着HDI/IPDI摩尔比增加,水性聚氨酯的乳液性能、软硬段的结晶性都得到提高,而胶膜拉伸强度呈先增大后减小的趋势,断裂伸长率则先减小后增大。所有WPU胶膜都有很好耐水性,胶膜吸水率都在5.0%（质量）以下。粘接实验结果表明,WPU胶黏剂对EVA/PVC具有优异的粘接性能,24 h后可对基材产生界面破坏,随着HDI/IPDI摩尔比增加,胶黏剂的粘接强度增大。当HDI/IPDI=7∶1时,水性聚氨酯的综合性能最好。