聚醚型聚氨酯弹性体的合成及其动态力学行为

采用两步合成法,以4,4′-二苯基甲烷二异氰酸酯(MDI)和1,4-丁二醇(BDO)为硬段,相对分子质量分别为1000、2000、4000的聚氧化丙烯二元醇(PPG)为软段,制备了一系列聚醚型聚氨酯(PUR)弹性体,研究了预聚体异氰酸酯指数R及软段相对分子质量对PUR动态力学性能的影响。结果表明,预聚体R值增大,即PUR的硬段含量增加,储能模量G′提高,软段相的玻璃化转变温度(Tg)升高,软硬相区的相容性增大;软段相对分子质量增加,PUR的G′下降,软段相的Tg降低,并出现硬段相的玻璃化转变,软硬相区的相分离程度增大。     

H_(12)MDI聚氨酯弹性体微相分离研究

以4,4′-二环己基甲烷二异氰酸酯(H12MDI)/1,4-丁二醇(BDO)为聚氨酯硬段,分别以聚四氢呋喃醚二醇(PTMEG)、聚己二酸丁二醇酯(PBA)为软段合成了硬段含量(质量分数,下同)为23%～50%的聚氨酯弹性体。借助IR、DSC等分析手段研究了其微相分离结构,并针对所制备弹性体进行力学性能表征。结果表明,硬段含量对H12MDI基弹性体的软段玻璃化温度影响很小;硬段含量的增加,PTMEG型PU的微相分离程度随之先降低后增加,而PBA型PU的微相分离程度则随之降低;以PBA为软段的H12MDI基弹性体在硬段含量为40%时力学性能达到最优。     

软段对热塑性聚氨酯弹性体结构及性能的影响

以二苯基甲烷-4,4′-二异氰酸酯(MDI)和扩链剂1,4-丁二醇(BDO)为聚氨酯弹性体硬段(控制硬段质量分数32%),以实验室自制聚己二酸乙二醇酯二醇(PEA)和聚己二酸乙二醇丙二醇酯二醇(PEPA)为软段,经预聚体法合成不同结构的热塑性聚氨酯弹性体(TPU)。研究了弹性体软段部分对其硬度、力学性能和结晶性能的影响。结果表明,控制热塑性聚氨酯弹性体硬段部分不变,改变软段,材料硬度变化不大;软段聚酯二元醇随其相对分子质量的增加,TPU力学性能和结晶性能均增强;研究不同PG含量的软段PEPA-TPU发现,当PG质量分数为10%时,TPU力学性能与结晶性能最好。     

硬段含量对聚氨酯脲弹性体力学性能的影响

以二苯基甲烷二异氰酸酯(MDI)与4,4'-双(仲丁基氨基)-二苯基甲烷为硬段、以聚氧化丙烯多元醇(PPG)为软段,采用半预聚法制备了一系列不同硬段含量的聚氨酯脲弹性体.通过静态力学性能测试、动态力学分析等研究手段,考察了硬段含量对聚氨酯脲弹性体力学性能及动态力学性能的影响.结果表明:40％～50％硬段含量弹性体的玻璃...     

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。     

聚酯软段对聚氨酯弹性体力学性能影响的研究

以不同结构聚酯多元醇(PEA、PEPA、PBA、PCL)为软段,4,4′-二苯基甲烷二异氰酸酯(MDI)和1,4-丁二醇(BDO)为硬段采用预聚法合成了聚氨酯(PU)弹性体。讨论了MDI/BDO体系中软段种类、相对分子质量、预聚体NCO含量及催化剂对PU弹性体力学性能的影响,并与TDI/MOCA体系进行比较。结果表明,当软段相对分子质量相同时,以PBA为原料合成的PU弹性体硬度最高,弹性体的拉伸强度、伸长率和冲击弹性均随软段相对分子质量的增加而增加;提高预聚体NCO含量可使PU弹性体的硬度、撕裂强度和300%模量增加;但加入催化剂的PU弹性体,其拉伸强度下降16.6%～20.1%;MDI/BDO体系PU弹性体的撕裂强度和冲击弹性较高,TDI/MOCA体系PU弹性体的拉伸强度较好、永久变形较低。     

采煤机械油缸密封材料用聚氨酯弹性体的研究

以聚四氢呋喃二醇(PTMG)和聚己内酯二醇(PCL)为软段原料,2,4-甲苯二异氰酸酯(2,4-TDI)、4,4'-二苯基甲烷二异氰酸酯(MDI)、3,3'-二氯-4,4'-二氨基二苯基甲烷(MOCA)和1,4-丁二醇(BDO)为硬段原料,采用预聚体法合成3种聚氨酯弹性体材料,研究了不同类型的聚氨酯弹性体的物理机械性能、高温物理机械性能以及耐乳化液性能。结果表明,聚氨酯弹性体PTMG-MDI-BDO和PCL-MDI-BDO的常温物理机械性能优于PTMG-TDI-MOCA; PTMG-TDI-MOCA在80℃和100℃下的高温物理机械性能优于PTMG-MDI-BDO和PCL-MDI-BDO;含MDI-BDO硬段的聚氨酯弹性体耐85℃水乳化液性能优于含TDI-MOCA硬段的。PCL-MDI-BDO是3种聚氨酯弹性体中最适合用作采煤机械液压支护设备油缸密封件的材料。     

硬段对热塑性聚氨酯弹性体结构及性能的影响

以实验室自制聚己二酸乙二醇酯二醇PEA为软段,二苯基甲烷-4,4’二异氰酸酯(MDI)为硬段,分别采用乙二醇(EG、1,4-丁二醇)、BOD和1,6-己二醇、HG为扩链剂,经预聚体法合成了硬段不同的聚氨酯弹性体。研究了硬段结构和硬段含量对弹性体硬度及力学性能的影响。采用旋转流变仪研究了弹性体在降温条件下的非等温结晶过程。结果表明,当硬段含量相同时,BDO-TPU结晶性能最好,拉伸强度最大;HG-TPU断裂伸长率最好。在BDO-TPU体系中,随硬段含量增加,材料硬度和强度增加,伸长率减小;结晶起始温度逐渐增大,结晶性能增强。     

耐酸碱聚氨酯弹性体胶辊的研制

以端羟基聚丁二烯(HTPB)和聚四亚甲基醚二醇(PTMEG)为软段,2,4-甲苯二异氰酸酯(TDI-100)和3,3′-二氯-4,4′-二氨基二苯基甲烷(MOCA)为硬段,采用预聚体法制备了聚氨酯弹性体,讨论了不同软段比例对弹性体力学性能、耐酸碱性能及加工性能的影响。结果表明,软段中HTPB与PTMEG质量比为50∶50时,弹性体的综合性能较好,适合做耐酸碱胶辊的包覆胶。     

三软段聚氨酯弹性体的制备和力学性能研究

采用半预聚体方法制备了系列由聚酯、聚醚二元醇及端羟基聚丁二烯为软段、液化MDI为硬段的三软段聚氨酯弹性体;研究了三软段聚氨酯弹性体的化学结构、力学性能及动态力学性能。结果表明,选择适当的软段组分和制备条件,通过半预聚体方式制备三软段聚氨酯弹性体是可行的。所有聚氨酯弹性体中MDI和软段羟基和交联剂羟基的反应较彻底,三软段可明显拓宽聚氨酯弹性体的玻璃化区域到150℃和有效阻尼温度范围(-30-30℃)。     

聚醚/聚酯型亲水性聚氨酯防水透湿性能研究

以4,4’-二苯基甲烷二异氰酸酯(MDI)和1,4-丁二醇(BDO)为硬单体,制备了6组聚醚与聚酯或不同聚醚混合单体为软链段的嵌段型亲水性聚氨酯防水透湿涂层剂。研究了聚氨酯材料的微结构和软段结构对其防水、透湿性能的影响。结果表明,亲水性聚氨酯软链段的结构、组成、相对分子质量和含量及软、硬段相区间的微相分离程度对材料防水透湿性能的影响较大,亲水性聚氨酯的防水透湿性能主要取决于其中亲水性软链段的亲水性及其活动性。     

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.     

4,4’-二氨基二苯醚扩链的聚氨酯应力松弛行为

以不同相对分子质量(Mn)的聚四氢呋喃二元醇为软段、4,4’-二苯甲烷二异氰酸酯和扩链剂4,4’-二氨基二苯醚为硬段,合成了一系列聚氨酯(PU)样品.从唯象的角度,利用标准线性粘弹(SLV)模型研究了其应力松弛特性,根据SLV模型的本构方程,计算出PU的两个松弛时间τ1和τ2,分析了软段Mn与硬段含量对其松弛行为的影响...     

合成革用脂肪族聚氨酯树脂的合成

以聚己二酸丁二醇酯二醇(PBA)为软段,异佛尔酮二异氰酸酯(IPDI)、异佛尔酮二胺(IP-DA)和1,4-丁二醇(BDO)为硬段,合成了不合N,N-二甲基甲酰胺(DMF)的弱极性溶剂型脂肪族聚氨酯树脂,考察了软段含量、二次扩链反应温度及nNCO/nOH值对聚氨酯树脂粘度及产品力学等性能的影响.结果表明,软段质量分数在...     

Preparation and properties of transparent thermoplastic segmented polyurethanes derived from different polyols

Various segmented polyurethanes of different soft segment structure with hard segment content of about 50 wt% were prepared from 4,4′‐diphenylmethane diisocyanate (MDI), 1,4‐butanediol and different polyols with a M_n of 2000 by a one‐shot, hand‐cast bulk polymerization method. The polyols used were a poly(tetramethylene ether)glycol, a poly(tetramethylene adipate)glycol, a polycaprolactonediol and two polycarbonatediols. The segmented polyurethanes were characterized by gel permeation chromatography (GPC), UV‐visible spectrometry, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X‐ray diffraction, and their tensile properties and Shore A hardness were determined. The DSC and DMA data indicate that the miscibility between the soft segments and the hard segments of the segmented polyurethanes is dependent on the type of the soft segment, and follows the order: polycarbonate segments > polyester segments > polyether segments. The miscibility between the soft segments and the hard segments plays an important role in determining the transparency of the segmented polyurethanes. As the miscibility increases, the transparency of the segmented polyurethanes increases accordingly. The segmented polyurethanes exhibit high elongation and show ductile behavior. The tensile properties are also affected by the type of the soft segment to some extent. POLYM. ENG. SCI., 47:695–701, 2007. © 2007 Society of Plastics Engineers.     

PCDL含量对混和软段的PUE相分离和阻尼性能的影响

以甲苯二异氰酸酯（TDI）、1,4-丁二醇（BDO）为硬段,聚碳酸酯二醇（PCDL）和聚醚二醇（PPG）混合物为软段,采用预聚体法制备了不同软段组成的聚氨酯弹性体（PUE）。采用DSC、FT—IR和DMA等分析手段研究了PCDL含量对PUE的微相分离程度和阻尼性能的影响。结果表明,随着软段中PCDL含量的增加,PUE中氨酯羰基的氢键化程度减小,相分离程度减小,而且PUE的储能模量随着PCDL含量的增加而减小;与单一组分软段的PUE相比较,混合软段的PUE具有相对较好的阻尼性能。     

Characterization of thermoplastic polyurethane adhesives with different hard/soft segment ratios containing rosin as an internal tackifier

Three thermoplastic polyurethanes (TPUs) containing different hard/soft (h/s) segment ratios (1.05-1.4) were prepared using the prepolymer method. MDI (diphenylmethane-4,4′diisocyanate) and polyadipate of 1,4-butanediol (M _w = 2440) were allowed to react to produce the prepolymer. To provide the polyurethanes with high immediate adhesion to different substrates, a rosin + 1,4-butanediol mixture (1 : 1 equivalent%) was used as chain extender (TPU-Rs). These TPU-Rs had two types of hard segments: (i) Urethane hard segments, produced by reaction of the isocyanate and the 1,4-butanediol, and (ii) Urethan-amide hard segments, produced by reaction of the isocyanate and the carboxylic acid functionality of the rosin. The TPUs and TPU-Rs were characterized using FTIR spectroscopy, gel permeation chromatography, differential scanning calorimetry, stress-controlled plate-plate rheology, stress-strain measurements, and Brookfield viscosity. The TPUs and TPU-Rs were used as raw materials to prepare solvent-based polyurethane adhesives, the adhesion properties of which were obtained from T-peel tests on PVC/polyurethane adhesive/PVC joints. The addition of rosin as an internal tackifier increased the average molecular weight, more markedly in the TPU-Rs containing higher hard/soft segment ratios, but the elastic and viscous moduli decreased. An increase in the hard/soft segment ratio of the TPU-Rs retarded the kinetics of crystallization (which was determined by the soft segment content in the polyurethane), and increased the immediate T-peel strength in PVC/polyurethane adhesive/PVC joints (which was determined by the urethan-amide hard segments). Furthermore, addition of rosin to the polyurethanes decreased the final adhesion, although always reasonably high peel strength values were obtained.     

Effect of the degree of soft and hard segment ordering on the morphology and mechanical behavior of semicrystalline segmented polyurethanes

The hierarchical microstructure responsible for the unique energy-absorbing properties of natural materials, like native spider silk and wood, motivated the development of segmented polyurethanes with soft segments containing multiple levels of order. As a first step in correlating the effects of crystallinity in the soft segment phase to the hard segment phase, we chose to examine the morphology and mechanical behavior of polyurethanes containing polyether soft blocks with varying tendencies to crystallize and phase segregate and the evolution of the microstructure with deformation. A series of high molecular weight polyurethanes containing poly(ethylene oxide) (PEO) (1000 and 4600 g/mol) and poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) (1900 g/mol) soft segments with varying hard segment content were synthesized using a two-step solution polymerization method. The presence of soft segment crystallinity (PEO 1000 g/mol) was shown to improve the storage modulus of the segmented polyurethanes below the T_m of the soft block and to enhance toughness compared to the PEO-PPO-PEO soft segment polyurethanes. We postulate that this enhancement in mechanical behavior is the result of crystalline soft regions that serve as an additional load-bearing component during deformation. Morphological characterization also revealed that the microstructure of the segmented polyurethanes shifts from soft segment continuous to interconnected and/or hard domain continuous with increasing hard segment size, resulting in diminished ultimate elongation, but enhanced initial moduli and tensile strengths. Tuning the soft segment phase crystallinity may ultimately lead to tougher polyurethane fibers.     

Structure–property relationships of thermoplastic polyurethane elastomers based on polycarbonate diols

The phase-separation behavior and morphology of polycarbonate-based polyurethanes were investigated as a function of the soft-segment molecular weight and chemical structure and the 4,4′-diphenylmethane diisocyanate/1,4-butanediol based hard-segment contents. Polarized optical microscopy and atomic force microscopy images showed that the surface morphologies changed as the soft-segment molecular weight and hard-segment content varied and also when the sample preparation conditions were modified. An increase in the soft- and hard-segment lengths led to increased phase separation with respect to the lower molecular weight soft segment, and this showed an interlocked and connected morphology of intermixed soft and hard domains. The surface morphology of phase-separated polyurethanes with hard segments composed of more than four to five 4,4′-diphenylmethane diisocyanate units contained globular hard-segment domains formed by spherulites, in which the size and connectivity between the branched lamellae changed with the hard-segment size. Interlamellar areas related to the soft segment were seen in the spherulites. Variations in the hard-segment spherulites were observed for polyurethanes based on soft segments of different molecular weights. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effect of H12MDI isomer composition on mechanical and physico-chemical properties of polyurethanes based on amorphous and semicrystalline soft segments

Two series of segmented thermoplastic polyurethanes were synthesized having 33 wt % hard segment based on 4,4′-dicyclohexyl methane diisocyanate with different trans–trans isomer contents and 1,3-propanediol chain extender. The soft segments were based on poly(hexamethylene–pentamethylene carbonate)diol and poly(butylene sebacate)diol, amorphous and semicrystalline polyol, respectively. 4,4′-Dicyclohexyl methane diisocyanate with different trans–trans isomer contents were obtained by fractional crystallization of commercial diisocyanate and were characterized by differential scanning calorimetry and nuclear magnetic resonance spectroscopy. 4,4′-Dicyclohexyl methane diisocyanate trans–trans isomer lead to some interesting properties in the synthesized polyurethanes, due to the more ordered hard domains formed by packing of trans–trans 4,4′-dicyclohexyl methane diisocyanate. Thereby, as 4,4′-dicyclohexyl methane diisocyanate trans–trans isomer content increased, a better phase separated structure was observed.