海水淡化工程用聚氨酯-脲防腐涂料

通过在配方中加入端羟基聚醚,制备了氨基甲酸酯/脲混杂硬段结构的聚氨酯-脲,探索了硬段含量对其性能的影响。经过差示扫描量热法(DSC)、动态力学性能(DMTA)、热失重分析(TG)等性能分析和评价,证明硬段质量分数为35%的聚氨酯-脲具有良好的机械性能、耐低温性能、耐腐蚀性能和热氧老化性能,适用于海水淡化工程。     

硬段含量对聚氨酯和聚氨酯脲氢键化程度的影响

以PPG600,PPG2000,甲苯二异氰酸酯(TDI)和1,4-丁二醇(1,4-BD)为原料合成了聚氨酯(PU),通过改变PPG600,PPG2000配比调节产品硬段含量;以PPG2000,TDI和异佛尔酮二胺(IPDA)为原料合成了聚氨酯脲(PUU),通过调节TDI与IPDA在体系中的比例调节产品硬段含量。利用FT-IR,DSC,旋转黏度计研究了硬段含量对聚醚型PU和PUU的微观结构及黏度的影响。结果表明,随硬段含量提高,PU和PUU的氢键化程度均提高,PU较多地形成不完善的氢键,而PUU倾向于形成完善有序的氢键结构。此外随硬段含量增大,PU和PUU的黏度增大,PU软段的玻璃化转变温度升高。     

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...     

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化转变温度(T_g)在室温附近(15～30℃),且具有较高的阻尼因子峰值(tanδ_max)、较宽的阻尼温域;随着硬段含量的升高,弹性体的拉伸强度、断裂伸长率逐渐升高,tanδ_max降低,T_g向高温方向移动。     

有机硅二醇对硅氧烷基聚氨酯弹性体的影响

以不同比例的PDMS(聚二甲基硅氧烷)/PPG(聚丙二醇)为混合软段,采用两步法合成了一系列硅氧烷基聚氨酯弹性体(SiPU)。通过FTIR(傅里叶变换红外)、接触角分析、耐酸碱介质试验、耐湿热老化试验、DMA(动态力学分析)和TGA(热重分析),研究了所制SiPU的结构、力学性能、表面性能、耐酸碱介质性能、耐湿热老化性能及热性能。结果表明:PDMS的含量明显影响SiPU的形态和性能:随PDMS的含量增大,接触角逐渐增大,材料的疏水性增强,拉伸强度和扯断伸长率先增大后减小,硬度、模量和撕裂强度逐渐提高,当w(PDMS)在10%～20%时显示最高的拉伸强度和断裂伸长率;SiPU耐碱性介质性能优于耐酸性介质性能,随PDMS的含量增大,耐酸性介质性能的拉伸强度保持率逐渐提高,耐碱性介质性能以w(PDMS)=20%最好;耐湿热老化性能则以w(PDMS)在25%～30%最好;在软段中引入适量的PDMS,有利于软硬段的微相分离和PU热稳定性的改善;PDMS含量过高会使PU的力学性能和热性能降低。     

水性聚氨酯-丙烯酸酯复合乳液的性能研究

用丙烯酸酯改性水性聚氨酯制备了具有核壳结构的水性聚氨酯-丙烯酸酯(WPUA)复合乳液,系统地研究了水性聚氨酯(PU)含量、nNCO/nOH(初始物质的量比)、亲水性扩链剂二羟甲基丙酸(DMPA)用量及软硬单体质量比对WPUA乳液及其膜的性能的影响.结果显示,WPUA乳液胶粒呈核壳型结构,聚丙烯酸酯(PA)与PU链段具有...     

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。     

超细纤维合成革用聚氨酯树脂的耐甲苯性研究

通过改变扩链剂、低聚物二醇种类及硬段比例合成了一系列聚氨酯(PU)树脂,利用差热分析手段研究了PU胶膜结晶性对其耐甲苯性的影响。研究表明,在低硬段含量下,扩链剂及低聚物二醇种类会对聚氨酯软段的结晶度产生较大的影响,且聚氨酯软段结晶度是影响PU胶膜甲苯溶胀率和甲苯抽出率的主要因素;软段结晶度越高,甲苯溶胀率和甲苯抽出率越低,PU胶膜耐甲苯性越好。另外,聚氨酯的硬段含量越高,甲苯溶胀率和甲苯抽出率越低,则PU胶膜的耐甲苯性越好。     

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。     

聚氨酯结晶性的研究进展

概述了聚氨酯(PU)结晶性的研究方法,讨论了软硬段种类和结构、硬段含量、软段相对分子质量、带电离子及其它基团和热处理等对PU结晶性的影响,并介绍了结晶性PU在形体记忆材料中的应用状况。     

A new core–shell type fluorinated acrylic and siliconated polyurethane hybrid emulsion

A novel core–shell type fluorinated acrylic and siliconated polyurethane (FSiPUA) hybrid emulsion was prepared by seeded emulsion polymerization using siliconated polyurethane (SiPU) as a seed and forming the structure with SiPU as a shell and the copolymer of butyl acrylate (BA) with 2,2,2-trifluoroethylmethacrylate (TFEMA) as a core. SiPU was synthesized using isophorone diisocyanate (IPDI), polytetramethylene ether glycol (PTMG), polypropylene glycol (PPG), dihydroxybutyl-terminated polydimethylsiloxane (PDMS), dimethylol propionic acid (DMPA), 1,6-hexanediol (HDO) and triethylamine (TEA). The contents of siloxane and fluorine were determined according to the feed ratio. Fourier transform infrared spectroscopy (FTIR) was used to identify the chain structure of SiPU and FSiPUA. Investigation of transmission electron microscopy (TEM) confirmed the core–shell structure of FSiPUA emulsion and gave the particle size at about 50 nm. The measurement results of water contact angles and the solvent absorptions in water and n-octane for cured films showed that the water and the oil repellency for FSiPUA had been improved significantly with a suitable content of fluorine and siloxane.     

Synthesis and characterization of linear and crosslinked poly(urethane urea) elastomers with triazine moieties in the main chain

A series of new poly(urethane urea) is synthesized via a two-step poly-addition process from polyether, 1,6-hexamethylene diisocyanate, 2,4-diamino-6-phenyl-1,3,5-triazine and different crosslinkers: glycerin or castor oil. The hard to soft segment ratio (OH_polyol/NCO/NH_{2chain extender}) was varied systematically from 1/2/1 to 1/4/3. Poly(tetramethylene glycol) of molecular weight 1,400 was used as the soft segment. The structural behavioral characterization of these polymers was performed through FTIR spectroscopy, thermogravimetric analysis, dynamic mechanical and thermal analysis, stress–strain measurements, and water contact angle measurements. The resulting linear polyurethane urea elastomers exhibit good mechanical properties with breaking strains of 300–890% and tensile strengths of 8–13.5 MPa. Thermogravimetric analysis indicated that the thermal degradation of poly(urethane urea) started at about 280–300 °C, higher than the degradation temperature of conventional polyurethane. The improvement of properties was influenced by the hard segment content and the nature of the crosslinker, but most of all by the structure and amount of the urea introduced through 2,4-diamino-6-phenyl-1,3,5-triazine into the polymer backbone chain.     

Phase transition and domain morphology of siloxane‐containing hard‐segmented polyurethane copolymers

The phase transitions and the morphology of hard‐segment domains of those siloxane‐containing hard‐segmented polyurethane copolymers are studied by differential scanning calorimetry (DSC). The NH‐SiPU2 copolymer, which comprises a siloxane–urea hard segment and a polytetramethylene ether glycol soft segment (PTMG2000), exhibits a high degree of phase‐separation and a highly amorphous structure. Therefore, NH‐SiPU2 copolymer proceeds with a melt‐quenching process and with various annealing conditions, to examine the morphologies and the endothermic behaviors of the siloxane‐containing hard‐segment domains. DSC thermograms of further annealed NH‐SiPU2 indicate that the first endotherm (T₁) at around 75°C is related to the short‐range ordering of amorphous siloxane hard‐segment domains (Region I), and the second endotherm (T₂) at around 160°C is related to the long‐range ordering of amorphous siloxane hard‐segment domains (Region II). The DSC thermograms at annealing temperatures below and above T₁ demonstrate that both the temperature and the enthalpy of T₁ linearly increase with the logarithmic annealing time (log t_a). This result shows that the endothermic behavior of T₁ is typical of enthalpy relaxation, which is caused by the physical aging of the amorphous siloxane hard segment. Additionally, the siloxane hard segments in Region I are movable, and can merge with the more stable Region II under suitable annealing conditions. Transmission electron microscopy shows that Regions I and II are around 200 and 800 nm wide, and that the Region I can be combined with the stable Region II, under suitable annealing conditions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4242–4252, 2006     

Morphology of water-blown flexible polyurethane foams

A series of four TDI–polypropylene oxide (PO) water-blown flexible polyurethane foams was produced in which the water content was varied from 2 to 5 pph at a constant isocyanate index of 110. A portion of each foam was thermally compression molded into a plaque. The morphology of both the foams and plaques was investigated using dynamic mechanical spectroscopy (DMS), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), scanning electron microscopy (SEM), swelling, wide angle X-ray scattering (WAXS), and small angle X-ray scattering (SAXS). A high degree of microphase separation occurs in these foams, and its degree is nearly independent of water (hard segment) content. In the foam with the lowest water content the morphology possesses many similarities to that of typical linear segmented urethane elastomers. Small hard segment domains are present with a correlation distance of about 7.0 nm. When the water content is increased a binodal distribution of hard segment material appears. There are the small hard segment domains typical of segmented urethane elastomers as well as larger “hard aggregates” greater than 100 nm in size. The larger domains are thought to be aggregates of rich polyurea that develop by precipitation during the foaming reaction. WAXS patterns of the foams suggest urea and possibly hard segment ordering that may be of a paracrystalline nature but certainly lacking in true 3-dimensional crystallinity.     

Exploring macro- and microlevel connectivity of the urea phase in slabstock flexible polyurethane foam formulations using lithium chloride as a probe

Urea phase connectivity has been probed by systematically varying the hard segment content, and lithium chloride content, in a series of plaques based on slabstock flexible polyurethane foams. The plaque formulations are identical to those of slabstock polyurethane foams with the exception that a surfactant is not utilized. Small angle X-ray scattering (SAXS) is used to demonstrate that all materials investigated are microphase separated with similar interdomain spacings, irrespective of hard segment content (21-37 wt%) or LiCl content. Several complimentary characterization techniques are employed to reveal that urea phase connectivity is present at different length scales. Macrolevel connectivity, or connectivity of the large-scale urea rich aggregates typically observed in flexible slabstock polyurethane foams, is probed using SAXS, TEM, and atomic force microscopy. These techniques collectively show that the urea aggregation increases as the hard segment content is increased. Incorporation of LiCl is shown to systematically reduce the urea aggregation behavior, thus leading to a loss in the macroconnectivity of the urea phase. Wide angle X-ray scattering is used to probe the regularity in segmental packing, or the microlevel connectivity between the hard segments, which is observed to decrease systematically on addition of LiCl. The loss in microlevel connectivity is suggested to increase chain slippage, and leads to increased rates of stress-relaxation for the samples containing LiCl. Materials containing LiCl also display relatively short rubbery plateaus as compared to their counterparts which do not contain the additive. Modulus values, as obtained at ambient conditions by stress-strain analyses, are found to be a stronger function of LiCl content when the hard segment content is higher.     

PDA型PUR弹性体的制备与性能

以聚己二酸二乙二醇酯二醇(PDA)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,采用预聚体法制备一系列PDA型PUR弹性体。采用力学性能测试、广角X射线衍射(WAXD)、傅立叶变换红外光谱(FTIR)、差示扫描量热(DSC)、热重(TG)分析和维卡软化点温度测定等研究手段,研究硬段含量对其力学性能、微观形态和热性能的影响。结果表明,随着硬段含量的增加,PDA型PUR弹性体的硬度、拉伸强度、300%定伸应力、拉伸永久变形和撕裂强度都增大,当硬段含量为40.1%时,弹性体的综合力学性能最佳,硬度(邵A)为88,拉伸强度为33.9 MPa,300%定伸应力为12.5 MPa,拉伸永久变形为31%,撕裂强度为90.3 k N/m;WAXD分析表明,弹性体为无定型结构;FTIR分析表明,硬段含量的增加使弹性体总的氢键化程度增加,微相分离程度改善;DSC测试表明,硬段含量的增加使弹性体的微相分离程度提高;TG和维卡软化点温度测试表明,弹性体的热性能随着硬段含量的增加而提高,当硬段含量为40.1%时,弹性体的初始分解温度(失重5%的温度)和维卡软化点温度分别达到324.5℃和144.1℃,具有较好的热性能。     

聚氨酯硬段含量变化对酪素/聚氨酯乳液及胶膜性能的影响

以异佛尔酮二异氰酸酯(IPDI)、聚四氢呋喃醚二醇(PTMEG1000)、二羟甲基丙酸(DMPA)、一缩二乙二醇(DEG)等为主要原料,固定酪素与聚氨酯的比例,通过改变聚氨酯硬段含量,制备出系列酪素/聚氨酯乳液(CWPU)。讨论了聚氨酯硬段含量的变化对CWPU状态、胶膜力学性能和热机械性能的影响。结果表明,随着聚氨酯硬段含量增加,聚氨酯分子之间、聚氨酯与酪素分子之间的氢键作用力增大,CWPU的粒径增大,分布变宽,乳液的粒径主要分布在100 nm左右;拉伸性能先增大后减小,硬段含量为64.61%时的拉伸强度达到41.75 MPa,断裂伸长率为344.75%。     

Preparation and properties of segmented thermoplastic polyurethane elastomers with two different soft segments

Thermoplastic polyurethane elastomers were prepared from 4,4‐diphenylmethane diisocyanate (MDI)/1,4‐butanediol (BD)/poly(propylene glycol) (PPG) and MDI/BD/poly(oxytetramethylene glycol) (PTMG). The MDI/BD‐based hard‐segment content of polyurethane prepared in this study was of 39–65 wt %. These polyurethane elastomers had a constant soft‐segment molecular weight (M_n , 2000), but a variable hard‐segment block length (n, 3.0–10.1; M_n , 1020–3434). The effects of the hard‐segment content on the thermal properties and elastic behavior were investigated. These properties of the PPG‐based MPP samples and the PTMG‐based MPT samples were compared. The polyurethane prepared in this study had a hard‐segment crystalline melting temperature in the range of 185.5–236.5°C. With increasing hard‐segment content, the dynamic storage modulus and glass transition temperature increased in both the MPP and MPT samples. The permanent set (%) increased with increasing hard‐segment content and successive maximum elongation. The permanent set (%) of the MPP samples was higher than that of MPT samples at the same hard‐segment content. The value of K (area of the hydrogen‐bonded carbonyl group/area of the free carbonyl group) increased with increasing hard‐segment content in both the MPP and MPT samples, and the K value of the MPT samples was higher than that of the MPP samples at the same hard‐segment content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 345–352, 1999     

Thermoplastic polyurethane–urea elastomers with superior mechanical and thermal properties prepared from alicyclic diisocyanate and diamine

High-performance thermoplastic polyurethane (TPU) elastomers have long been the objective of numerous studies. In this work, thermoplastic polyurethane–urea (TPUU) elastomers with balanced superior mechanical and thermal properties, in comparison with the rare cases of high-performance TPU/TPUU elastomers with super-high tensile strength, were synthesized by the reaction of polycarbonate diols with excess alicyclic isophorone diisocyanate, followed by the chain extension of alicyclic isophorone diamine. When the content of hard segment was around 47%, the TPUU elastomer had super-high tensile strength of 51.7 MPa, initial elastic modulus of 698 MPa and elongation at break of 480%. The temperature range of this TPUU elastomer's rubbery state was up to 120°C with storage modulus above 200 MPa, and its rubbery flow state reached 200°C where the storage modulus was still as high as 100 MPa. Fourier transform infrared spectroscopy analysis indicated the presence of strongly hydrogen bonded urethane and urea groups in these TPUU elastomers. Atomic force microscopy and differential scanning calorimetry studies demonstrated significant and nearly perfect microphase separation in these TPUU elastomers when the hard segment content was around or below 47%. These noncrystalline TPUU elastomers could be thermally processed or processed in the form of a solution.     

Influence of Hard Segment on Thermal Degradation of Thermoplastic Segmented Polyurethane for Textile Coating Application

An attempt has been made to investigate the thermal degradation of thermoplastic segmented polyurethane (TSPU) as a function of hard segment (HS) content. TSPU, and its corresponding hard segment and soft segment, has been studied in air and nitrogen. Comparing the results of solid conversion of polyurethane in different conditions (air and nitrogen), significant differences were observed. Derivative thermogrametry (DTG) analysis revealed that the degradation was a three-step weight loss process in air and two steps in nitrogen. Multiphase degradation occurs in air due to the oxidation reaction of polymer. Therefore, an extra peak appeared in air (in the temperature range between 509 and 583°C). Degradation temperature of 10% (T₁₀) and the temperature of half-decomposition (T_d,1/2) increased with decreasing hard segment content in the TSPU. Thermal stability of polyurethanes decreased after introduction of hydrophilic segment (PEG-200) in the polymer backbone due to the increasing oxygen molecules. The surfaces of the original films, detected by scanning electron microscopy (SEM), were smooth. However, stress cracking was observed for heat-treated deformed TSPU films with higher hard segment content.