氯水老化pH值对氨纶结构与性能的影响

为了研究氯水老化pH值对氨纶的影响,使用不同pH值的次氯酸钠溶液对氨纶进行老化处理,随后采用傅里叶变换红外光谱、X射线衍射、差示扫描量热及力学性能测试分析老化后样品的氢键化程度、微相分离程度、结晶性、热性能与拉伸性能。结果表明:氨纶氢键化程度、微相分离程度和硬段结晶度都随氯水p H值的降低而减弱。在热性能方面,随着氯水pH值的降低,氨纶的玻璃化转变温度与软段结晶熔融温度升高,软段结晶度减小。在拉伸力学性能方面,低pH值氯水处理后的氨纶表现出更小的断裂强力和断裂伸长率。     

甬道风量对干纺氨纶结构与性能的影响

采用聚四亚甲基醚二醇、4,4'–二苯基甲烷–二异氰酸酯、乙二胺、N,N–二甲基乙酰胺制成纺丝原液,分别在甬道风量为630,660,690,720,750 m3/h下制备了5种干纺氨纶。利用傅立叶变换红外光谱仪、X射线衍射测试仪、差示扫描量热仪、万能材料试验机研究了5种氨纶的氢键、热性能、结晶性以及拉伸性能。结果表明,随着甬道风量的增加,氨纶硬链段内部氢键化程度降低、结晶度降低,导致氨纶拉伸断裂强力降低;软链段局部取向程度降低、玻璃化转变温度降低,导致氨纶拉伸断裂伸长率增大。     

硬段含量对MDI型热塑性聚氨酯性能的影响

以4,4'-二苯基甲烷二异氰酸酯(MDI)、聚四亚甲基醚二醇(PTMG)和1,3-丙二醇(PDO)为原料,采用预聚体法合成热塑性聚氨酯(TPU),利用FTIR、DSC及力学性能测试等手段探究了硬段含量对TPU性能的影响。结果表明,硬段含量增加,TPU的氢键化程度、玻璃化转变温度、硬段熔融温度、拉伸强度、撕裂强度、硬度和模量均随之增大,软段结晶熔融温度及断裂伸长率随之减小;在硬段质量分数33%～45%范围内,TPU呈现"海-岛"结构,且随硬段含量增加,微相分离程度逐渐增加。     

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。     

高透明聚氨酯脲弹性体的制备与性能

以聚四氢呋喃醚二醇（PTMG）为软段，4,4’-二环己基甲烷二异氰酸酯（HMDI）和异佛尔酮二胺（IPDA）为硬段，采用预聚体法制备四种高透明的聚氨酯脲（PUU）弹性体。对PUU弹性体进行红外光谱、紫外光谱、力学性能、热学性能和流变性能等测试。结果表明：四种透明PUU弹性体均为无定型结构，在450 nm处紫外透过率均高于89.8%。随着硬段含量的增加，PUU弹性体的硬度、100%定伸模量和拉伸强度均增加，而断裂伸长率下降。PUU-2.7的硬度、100%定伸模量和拉伸强度分别达到92.5、18.3 MPa和53.7 MPa。PUU-1.5试样只有一个玻璃化转变温度，微相分离程度最低。硬段含量的增加，使PUU弹性体硬段间氢键作用增强，微相分离程度增大。     

聚硅氧烷／聚氨酯膜的结构特性和气体渗透性能

用红外光谱、差示扫描色谱、透射式电子显微镜表征了由聚环氧丙烷基聚氨酯预聚体(PU)与双羟基聚硅氧烷(PDMS)反应制备而成的含有聚硅氧烷软段的聚氨酯薄膜。得出这两种软段发生相分离,硬段基团在软段中形成小的聚集体。气体渗透实验发现CO2、O2和N2的渗透性能随着聚硅氧烷软段含量的增大而增大,而渗透比P(CO2)/P(N2)和P(O2)/P(N2)没有明显改变。交联度低以及硬段中氢键分布少时,聚硅氧烷软段膜含量大,渗透性也大。     

聚醚型聚氨酯的氢键、微相分离及性能

用本体一步法合成了5种不同硬段含量(11.0％～46.9％)的二苯甲烷-4,4′-二异氰酸酯/环氧乙烷封端型聚环氧丙烷聚醚/乙二醇的聚醚型聚氨酯,并借助于IR,DSC,DMS和材料试验机等手段对该聚氨酯的氢键、微相分离及力学性能进行了表征。结果表明:随着硬段含量的增加,其>NH与微区中的>C=O的氢键化程度逐渐提高,软段微区中—O—的氢键化程度逐渐降低;微相分离程度逐渐提高;拉伸强度及硬度随之增加,扯断伸长率在硬段含量40％左右出现极大值。     

聚酯型聚氨酯乳液的合成及性能

以异佛尔酮二异氰酸酯（ IPDI）、六亚甲基二异氰酸酯（HDI）和聚己二酸 1,4-丁二醇酯二醇（ PBA）为主要原料制备系列水性聚氨酯乳液（ WPU）。采用红外光谱仪、差式扫描量热仪、 X-射线衍射仪、电子拉力机等对 WPU进行结构表征;为了从聚集状态上对聚氨酯结晶性有更深层次的探究,对 WPU进行了定伸情况下的测试。结果显示：随着硬段含量的增加,硬段 -软段间的氢键相互作用减小,微相分离程度增加,结晶性能降低;随着伸长率的增加,氢键相互作用和结晶性能都表现出先减小后增大的趋势。当硬段含量为 14. 73%时,聚氨酯胶膜拉伸强度达到 40. 11 MPa,剥离强度为 93. 7 N/（25 mm）。     

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。     

无助溶剂水性聚氨酯的制备及相关性能研究

以2,2-二羟甲基丙酸(DMPA)和1,4-丁二醇(BDO)为原料,制备了一种低熔点扩链剂(LMCE)。通过差示扫描量热和广角X射线衍射分析,研究了不同DMPA/BDO物质的量比对LMCE熔点和晶体结构的影响。以异佛尔酮二异氰酸酯和LMCE为硬段、分别以分子量为1 000、2 000和3 000的聚ε-己内酯二醇为软段,制备了一系列无助溶剂水性聚氨酯。通过粒径分析、差示扫描量热、动态力学分析和力学性能测试等,研究了所制备水性聚氨酯的结构与性能。结果表明:随着DMPA/BDO物质的量比的减小,LMCE的熔点逐渐降低,结晶度下降;随着软段分子量的增加,水性聚氨酯的乳液粒径先减小后增大,微相分离程度和软段结晶性提高;力学性能测试结果表明软段分子量的增加可以提高水性聚氨酯的拉伸强度和断裂伸长率。     

乙烯脲改性水性聚氨酯脲的制备与性能

采用一种新型的扩链剂乙烯脲(EU),在聚氨酯硬段引入具有刚性环状二取代脲基团,通过控制脲含量、交联度以及软段相对分子质量来制备一系列的EU改性水性聚氨酯脲(PUU-EU),并利用透射电镜(TEM)、广角X射线衍射(WAXD)、动态力学机械分析(DMA)、热失重分析(TGA)等测试方法,系统地研究PUU-EU微观结构与氢键化程度、微相分离、耐热性、力学强度的关系,并与1,4-丁二醇(BDO)扩链制备的水性聚氨酯(WPU)进行对比。结果表明,在一定范围内,PUU-EU随脲含量增加,其氢键化程度愈发完善,微相分离程度随之增加,力学强度逐步提高。     

Influence of heat treatment on the properties of shape memory fibers. I. Crystallinity,hydrogen bonding,and shape memory effect

Shape memory fibers (SMFs) were prepared via melt spinning. The fibers underwent different heat treatments to eliminate internal stress and structure deficiency caused during melt spinning. The influences of heat treatments on the SMF crystallinity, molecular orientation, hydrogen bonding, and shape memory behavior were studied. It was found with increasing heat‐treatment temperature, the soft segment crystallinity, crystallite dimension, and microphase separation increased, and the hydrogen bonding in the hard segment phase increased. Low temperature heat treatments decreased the shape recovery ratios while increasing the shape fixity ratios as a result of internal stress releasing and molecules disorientation. High temperature heat treatments increased the hard segment stability. Increasing heat‐treatment temperature resulted in the improvement of both the shape recovery and fixity, because it promoted the phase separation. The results from DSC, DMA, XRD, and FTIR were used to illustrate the mechanism governing these properties difference. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

高固含量水性聚氨酯的合成及其成膜性能的研究

采用预聚体分散法制备出50%以上固含量的水性聚氨酯,考察了软链段分子链长及硬链段含量对聚氨酯相分离行为、热性能及力学性能等的影响。研究表明:硬链段含量、软链段链长的提高和离子基团的增加均有利于拉伸强度的提高。     

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。     

Study on microstructure of UV-curable polyurethane acrylate films

UV-curable polyurethane acrylates (UVPUA) were prepared, and Fourier transform infrared (FTIR) was used to monitor the synthesis process and cured films. Effects of soft segment length, isocyanate type, reactive diluent type and level, quenching, annealing and different UV-cured degree on the microstructure of UVPUA films have also been studied. With soft segment length increasing, the degree of hydrogen bonding between soft segment and hard segments decreases, and microphase separation of UVPUA becomes better. Soft segment crystallization appears with its molecular weight exceeding 2000, when its value reaches 4000, an even more obvious melting peak in differential scanning calorimetry (DSC) curve was observed. Congregation of hard segment domains and the improvement of phase separation were due to symmetry and regularity of isocyanate, while rigid benzene ring was beneficial to crystallize and increase the glass transition temperature (T_g). The increased crosslink density with increasing the function degree of diluent resulted in better phase separation, on the contrary, increasing the reactive diluent content led to the opposite because of a phase reversion. Microphase separation lower during quenching and annealing due to post-curing of 1,6-hexa-nediol diacrylate (HDDA) at high temperature, and with the UV-cured degree increasing, the phase separation got better first and then became worse.     

Multiscale Modeling of the Morphology and Properties of Segmented Silicone-Urea Copolymers

Abstract  

Molecular dynamics and mesoscale dynamics simulation techniques were used to investigate the effect of hydrogen bonding on the microphase separation, morphology and various physicochemical properties of segmented silicone-urea copolymers. Model silicone-urea copolymers investigated were based on the stoichiometric combinations of α,ω-aminopropyl terminated polydimethylsiloxane (PDMS) oligomers with number average molecular weights ranging from 700 to 15,000 g/mole and bis(4-isocyanatocyclohexyl)methane (HMDI). Urea hard segment contents of the copolymers, which were determined by the PDMS molecular weight, were in 1.7–34% by weight range. Since no chain extenders were used, urea hard segments in all copolymers were of uniform length. Simulation results clearly demonstrated the presence of very good microphase separation in all silicone-urea copolymers, even for the copolymer with 1.7% by weight hard segment content. Experimentally reported enhanced properties of these materials were shown to stem from strong hydrogen bond interactions which leads to the aggregation of urea hard segments and reinforcement of the PDMS.     

蓖麻油作交联剂的聚氨酯弹性体的合成及性能

以不同摩尔比的四氢呋喃均聚醚（PTMG）和1,6-亚己基二异氰酸酯（HDI）合成聚氨酯（PU）预聚体,再分别用丁二醇（BD）、蓖麻油（CO）以及BD和CO混合物进行扩链交联,合成了一系列不同CO含量的PU.通过FTIR、AFM、拉伸实验和TGA,对不同硬段含量和CO含量PU的氢键化程度、相形态结构、力学性能和热性能进行了比较。结果表明,二异氰酸酯和扩链剂的种类及用量对PU的性能均有很大的影响。随着PU中二异氰酸酯用量的增加,其力学性能和热稳定性能提高。随着扩链剂中CO用量的增加,PU氨酯键的氢键化程度降低,其软、硬段的微相分离程度降低,导致其力学性能降低。但CO用量的增加会提高PU分子链的交联和支化,因而其热稳定性能得到提高。     

Structure–property relationships of poly(urethane–urea)s with ultra-low monol content poly(propylene glycol) soft segments. Part II. Influence of low molecular weight polyol components

Segmented poly(urethane–urea)s have been synthesized with mixed soft segments of ultra-low monol content poly(propylene glycol) (PPG) and tri(propylene glycol) (TPG) which allows the fabrication of quality elastomers without crosslinking. The narrow molecular weight distribution of the ultra-low monol content PPG polyols allows for the probing of the influence of the low molecular components of the molecular weight distribution through the inclusion of low molecular homologs of PPG such as TPG. Structure–property relationships for these materials were investigated as average soft segment molecular weight was varied by blending 8000 g/mol PPG with TPG to achieve molecular weights of 2500, 2000, and 1500 g/mol. Morphological features such as microphase separation, interdomain spacing and interphase thickness were quantified and revealed with SAXS. AFM was utilized to verify the microphase separation characteristics inferred by SAXS. The thermal and mechanical behavior was assessed through applications of DMA, DSC, and conventional mechanical tests. It was found that as the average soft segment molecular weight was decreased through the addition of TPG, the interdomain spacing distinctly increased contrary to the trend seen for decreasing soft segment molecular weight in PPG based systems without TPG. Additionally, the inclusion of TPG in the poly(urethane–urea) formulations resulted in the formation of larger hard domains as evidenced by AFM. These results and supporting evidence from DMA, DSC, birefringence, and mechanical testing led to the conclusion that TPG apparently acts more as a chain extender as well as, or in contrast to, a soft segment.     

Inelastic response of copolyurethane elastomers with varying soft segment molecular weights and preparation procedure

A family of thermoplastic polyurethane elastomers (TPUs) based on the soft segment poly(oxytetramethylene) (PTMO₂₀₀₀ and PTMO₁₀₀₀) were synthesized by the one‐shot and prepolymer methods. Two hard segments were chosen, 4,4′‐methylenebis(phenyl isocyanate) (MDI) (non‐crystallizable) and 4,4′‐dibenzyl diisocyanate (DBDI) (crystallizable). Microphase separation and crystallinity were investigated using small‐angle X‐ray scattering and wide‐angle X‐ray scattering, and dynamic viscoelastic properties were also determined. An increased hard phase degree of crystallinity was primarily achieved by use of DBDI instead of MDI, regardless of the preparation procedure and soft segment molecular weight. An increase of the molecular weight leads to an increase in phase separation and to a decrease in hysteresis. For the DBDI based polymers, a lower soft segment molecular weight resulted in an increase in crystallinity. The DBDI series of TPUs obtained by the one‐shot and prepolymer methods showed higher hysteresis and residual elongations compared with the corresponding materials achieved with MDI. Although the materials varied widely in response to first loading, regardless of the preparation procedure, they displayed remarkable reproducibility and commonality in cyclic responses within the maximum strain envelope. The thermomechanical experiments revealed a better thermal behavior with increase of the soft segment molecular weight from PTMO₁₀₀₀ to PTMO₂₀₀₀.© 2013 Society of Chemical Industry     

Thermoplastic polyurethane elastomers based on polycarbonate diols with different soft segment molecular weight and chemical structure: Mechanical and thermal properties

A series of thermoplastic polyurethane elastomers based on polycarbonate diol, 4,4′‐diphenylmethane diisocyanate and 1,4‐butanediol was synthesized in bulk by two‐step polymerization varying polycarbonate diol soft segment molecular weight and chemical structure, and also hard segment content, and their effects on the thermal and mechanical properties were investigated. Dynamic mechanical analysis termogravimetric analysis, differential scanning calorimetry, Fourier transform infrared‐attenuated total reflection spectroscopy and mechanical tests were employed to characterize the polyurethanes. Thermal and mechanical properties are discussed from the viewpoint of microphase domain separation of hard and soft segments. On one hand, an increase in soft segment length, and on the other hand an increase in the hard segment content, i.e., hard segment molecular weight, was accompanied by an increase in the microphase separation degree, hard domain order and crystallinity, and stiffness. In phase separated systems more developed reinforcing hard domain structure is observed. These hard segment structures, in addition to the elastic nature of soft segment, provide enough physical crosslink sites to have elastomeric behavior. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers