不同异氰酸酯型聚氨酯弹性体的制备与力学性能研究

采用不同结构的异氰酸酯和多元醇制备了一系列聚氨酯弹性体,主要考察了异氰酸酯种类对聚氨酯弹性体力学性能的影响.研究表明,由1,5-萘二异氰酸酯制得的弹性体拉伸强度和撕裂强度较高,分别为38.75MPa和109.77 kN/m,而由对苯二异氰酸酯制得的弹性体具有最大的扯断伸长率(557.84％).此外还研究了多元醇种类和扩链系数α对弹性体力学性能的影响,研究表明,选用聚ε-己内酯二醇制得的弹性体具有较好的性能,且拉伸强度和撕裂强度均随扩链系数的增大先增大后减小,而扯断伸长率一直增大.     

硬段对聚酯型聚氨酯弹性体微相分离的影响

以聚己二酸-1,4-丁二醇酯二醇(PBA)、4,4′-二苯基甲烷二异氰酸酯(MDI)、乙二醇(EG)、1,4-丁二醇(BDO)和1,6-己二醇(HD)等为主要原料,采用预聚体法制备了一系列热塑性聚氨酯弹性体(TPU)。通过对TPU流变性能、结晶性能、硬度与力学性能的研究,考察了不同扩链剂及不同硬段含量对TPU体系内部微相分离的影响。结果表明,HD-TPU与BDO-TPU微相分离情况相当,均大于EGTPU,且HD-TPU具有较好的结晶性能、拉伸强度及断裂伸长率;随TPU体系硬段含量增加,硬度和拉伸强度增加,断裂伸长率减小,相分离发生越早越快,结晶熔融温度越高,但相分离程度并不高。     

聚醚-聚硅氧烷嵌段共混聚氨酯弹性体的研究

用共聚混合法制成聚硅氧烷-聚醚型嵌段聚氨酯,结果表明:在聚合物主链引入硅氧烷后,弹性体力学性能略有升高,对三元乙丙橡胶,异戊二烯橡胶的粘合剥离强度得到提高。NCO/OH当量比、硅氧烷和MOCA用量对材料的物理性能有很大的影响。DSC的分析表明,引入的聚硅氧烷链段主要分布于弹性体分子中的软段,使弹性体的相分离更加明显。     

聚氨酯弹性体的力学性能影响因素研究

研究了合成方法,软段及硬段组成结构,熟化条件等因素对聚氨酯弹性和学性能的影响,结果表明,聚氨酯弹性体的结构与组成,以及由此引起微相分离程度的变化,是影响弹性体性能的重要因素,不同的低聚物二醇,二异氰酸酯及扩链剂合成的弹性体性能不同,采用预聚法,以及适当熟化有助于提高弹性体的性能。     

Effect of clay dispersion on the rheological properties and flammability of polyurethane‐clay nanocomposite elastomers

Polyurethane‐clay nanocomposite elastomers were synthesized using polyol‐clay blends with different levels of dispersion, which affected the final elastomer microstructure. A PU‐clay microcomposite elastomer containing partially dispersed clay showed poorer mechanical and similar fire properties to the unmodified polyurethane. More complete dispersion of the clay into the polyol led to an exfoliated structure in the final elastomer. This showed a higher modulus and kept a viscoelastic behavior to higher temperature than the pristine PU. The enhancement of mechanical and thermal properties in the nanocomposite elastomer can be attributed to the degree of clay exfoliation, and this also prevented dripping during the UL 94 fire test. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

异氰脲酸酯基团对聚氨酯弹性体性能影响研究

引入异氰脲酸酯基团可提高聚氨酯弹性体的耐热性能,但同时对其他性能有一定影响。通过改变NCO含量考察异氰脲酸酯基团对聚氨酯弹性体的力学性能及耐溶剂性能的影响。力学性能测试结果表明,其硬度、拉伸强度和撕裂强度均在NCO质量分数为8％时达到极大值,分别为邵A60、10．33MPa和48．84kN／m,扯断伸长率随NCO含量增加单调减小,100％定伸强度单侧增大;耐溶剂实验表明,聚氨酯弹性体在NCO质最分数为8％时耐溶剂性能最好。     

聚合物聚酯多元醇在鞋底料中的应用

以聚酯多元醇、聚合物聚酯多元醇、4，4′-二苯基甲烷二异氰酸酯等为原料，采用半预聚体法制备了聚氨酯微孔弹性体鞋底，讨论了操作温度对A组分粘度、聚合物聚酯多元醇对聚氨酯微孔弹性体性能及鞋底泡孔结构的影响。结果表明，聚合物聚酯多元醇用于制备聚氨酯微孔弹性体，能够增强弹性体的硬度、强度等机械性能，改善弹性体的泡孔结构；虽然A组分的粘度略有增加，但不会影响工艺，在使用温度范围内可调节。     

聚醚型高硬度聚氨酯弹性体的研制

采用聚氧化丙烯多元醇、二醇扩链剂和多异氰酸酯为原料，用一步法工艺制得一系列高硬度聚氨酯弹性体。讨论了多元醇组分平均每个羟基所对应的链段的相对分子质量(MOH)、平均官能度以及异氰酸酯种类对高硬度聚氨酯弹性体性能的影响。结果表明，采用液化MDI或粗MDI与聚氧化丙烯醚配合使用可以制得邵D硬度大于65的聚醚型高硬度聚氨酯弹性体。     

Morphology and mechanical properties of rubber modified aromatic-ether bismaleimide matrix resins

An aromatic ether bismaleimide (BMI) was modified by copolymerization with various CTBN and ATBN liquid elastomers. Dynamic mechanical (DMA), flexural, and SEM fractography studies indicate that cured specimens containing various amounts of the different elastomers have widely varying morphologies and properties. The experimental parameters of interest in this study included the type of elastomer reactive end group, elastomer acrylonitrile content, elastomer concentration, and cure reaction conditions. The ATBNs are clearly more compatible than CTBNs. CTBN modified compositions show a distinct, low temperature rubber phase mechanical loss dispersion, reduced modulus and ultimate strength values, and only slight improvements in elongation. Cured compositions with small amounts of ATBN elastomers (5 phr), however, show no reduction in modulus but improved elongation and ultimate strength values. The “rubber” domains in these systems are small, typically < 5 μm, and consist of copolymerized BMI and elastomer. DMA data for these systems show no distinct low temperature elastomer peak but a broad “interphase” loss dispersion covering a wide range of temperatures. Failure in the ATBN modified BMIs involves initiation of numerous microcracks with obvious crack deflection at the rubber particles. No cavitation of rubber particles occurs, as is frequently the case with the CTBNs.     

制备工艺对木质素基弹性体力学性能的影响

利用聚醚多元醇在硫酸存在下直接与木质素反应制备木质素基弹性体并研究了制备工艺对弹性体力学性能的影响。结果表明：通过提高聚醚多元醇和木质素质量比、聚醚多元醇中聚丙二醇（PPG）比例、浓硫酸用量、提高液化温度和延长固化时间可以有效提升弹性体的拉伸强度,但扯断伸长率会降低;适当加入增塑剂丙三醇可同时提高其拉伸强度和扯断伸长率,但加入过多会使力学性能降低。通过平衡弹性体的拉伸强度和扯断伸长率,较优的工艺条件为液固比（多元醇和木质素质量比）1.8∶1,多元醇中PEG和PPG质量比1∶1.2,催化剂用量2%,增塑剂用量10%,液化温度120℃,固化时间10 h,此时制得的木质素基弹性体的拉伸强度3.64 MPa,扯断伸长率173%。FT-IR分析表明将木质素、多元醇PEG和PPG以及浓硫酸直接混合而未高温液化情况下,并不会让它们之间的活性基团发生化学反应,而仅仅是物理性的混合;在高温液化时,体系开始发生酯化反应,并在高温固化阶段反应程度进一步提高,同时固化阶段还发生烷基化反应和缩合反应。     

Mechanical properties of hybrid structural composites reinforced with nanosilica

Epoxy‐based hybrid structural composites reinforced with 14 nm spherical silica particles were investigated for mechanical properties as a function of nanosilica loading fractions. Composites were fabricated using continuous glass or carbon fiber of unidirectional architecture and nanosilica dispersed epoxy, through resin film infusion process. Uniform dispersion of nanoparticles in resin matrix was ensured by an optimized ultrasound‐assisted process. Although resin viscosity marginally reduces in the presence of nanosilica enabling a better control in composite manufacturing process, glass transition temperature of epoxy remained unaffected at low weight fractions. Compressive strength of hybrid glass or carbon fiber/epoxy composites showed more than 30–35% increase with nanosilica at a concentration as low as 0.2 wt%. Tensile and compressive properties of hybrid composites in transverse direction to the reinforcement remained unaffected. POLYM. COMPOS. 37:1216–1222, 2016. © 2014 Society of Plastics Engineers     

The structure and physical properties of polypropylene and thermoplastic olefin nanocomposites containing nanosilica

The morphology and physical properties of thermoplastic olefin blend (TPO) based nanocomposites containing nanosilica are reported. Addition of maleated PP resulted in improved filler dispersion within the PP matrix, where the filler resided exclusively. This separated morphology resulted in selective reinforcement of the PP matrix without compromising ductility, as demonstrated by mechanical property characterization. The tensile moduli, impact and flexural properties of TPO/nanosilica composites showed improvements at low loadings of nanosilica, indicating a good balance of stiffness and toughness. The addition of nanosilica into the TPOs decreased the size of the dispersed elastomer phase, which was a factor in the observed improvements of impact strength. Silane-modified nanosilica dispersed more efficiently in the polymer matrix, giving rise to improved impact properties of the TPO composites, compared to the unmodified filler.     

Zeolites as reinforcing fillers in an elastomer

Summary Two zeolites that were both silicates of sodium and aluminum but of different pore size were blended into samples of hydroxyl-terminated poly(dimethylsiloxane), which were then end linked into elastomeric networks. Stress-strain isotherms measured in elongation showed that both types of zeolites increased the ultimate properties of the elastomer and were thus effective reinforcing fillers. The one having the larger pore size gave larger increases in the ultimate strength of the elastomers.     

不同弹性体增韧聚丙烯的研究

通过双螺杆挤出机制备了三种不同的弹性体EPR、EPDM、POE与PP的共混物,测试了共混物的力学性能, 比较了三种弹性体的增韧效率。结果表明:三种弹性体都是PP有效的增韧剂,其中POE的增韧效率最高,其冲击强度是纯PP的25倍。通过扫描电镜观察了弹性体在PP中的分散,发现POE在基体中相区尺寸最小,其冲击强度最大;EPDM相区尺寸最大,其冲击强度最小,这意味着共混物的相形态与性能有很好的相关性,三种弹性体在PP中分散尺寸不同的主要原因是由于弹性体与PP的黏度比不同引起的。DMA分析表明低模量的弹性体有利于提高共混物的韧性。     

Effects of polyol molecular weight on properties of benzoxazine–urethane polymer alloys

Recently, a new thermoset resin namely benzoxazine (BA) resin has been developed. The polymer possesses several outstanding properties, such as, ease of synthesis, low viscosity, near‐zero shrinkage, lack of by‐product upon curing, high thermal stability, and high mechanical property. Moreover, the benzoxazine resins can be alloyed with various types of resins because of the various function groups in their structure. In this work, urethane elastomer (PU) is used to enhance toughness of the polybenzoxazine. The effects of polyol molecular weights on the properties of BA: PU polymer alloys are investigated. The experiment reveals that the similar curing peaks of the matrices at various polyol molecular weights, with the same urethane mass fraction, in the resin mixtures are obtained. The glass transition temperature increases from 160°C of polybenzoxazine to 240–245°C in the 70:30 BA:PU system. In addition, the char yield increases when the higher molecular weight of polyol is added. The flexural modulus of polybenzoxazine decreases from 6.2 GPa to be in the range of 2.2–2.8 GPa when 30 wt% of PU is presented in the alloys. Furthermore, the synergism with ultimate flexural strength is observed in the 90:10 BA:PU alloy for all molecular weights of the polyol used. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

E-100扩链的聚氨酯弹性体性能的研究

以不同相对分子质量的聚醚多元醇(PPG)、TDI和3,5-二乙基甲苯二胺(DETDA)为原料,采用溶剂法合成了聚氨酯(PU)弹性体,分别研究了溶剂种类、NCO含量、聚醚多元醇相对分子质量、扩链系数等对PU弹性体力学性能的影响。结果表明,二甲苯对PU弹性体性能影响最小;PU弹性体的硬度、定伸模量、拉伸强度和撕裂强度随聚醚多元醇的相对分子质量的升高而下降,冲击弹性、伸长率和永久变形随聚醚多元醇的相对分子质量的升高而上升;当预聚体NCO质量分数为6.30%、扩链系数为0.95时,PU弹性体的综合力学性能最佳。     

POE/硅橡胶热塑性弹性体的力学性能及加工性能研究

采用动态硫化方法制备了乙烯-丙烯共聚物(POE)/硅橡胶热塑性弹性体。考察了共混比和交联剂含量对POE/硅橡胶热塑性弹性体的力学性能以及流变加工特性的影响。结果表明,m(硅橡胶)/m(POE)为60/40,交联剂质量分数为2.5%时表现出优越的力学性能,拉伸强度达到9.8MPa,断裂伸长率达到740%。制备出的POE/硅橡胶在流变测试中表现出优越的流变性能,具有高剪切粘度低,低剪切粘度高的特点。     

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。     

聚氨酯型遇水膨胀弹性材料的研制

研究了聚氨酯型遇水膨胀弹性材料中多元醇种类及分子量、－NCO基团含量、弹性材料的交联度等因素对吸水膨胀性能及力学性能的影响。     

Preparation and characterization of thermoplastic olefin/nanosilica composites using a silane-grafted polypropylene matrix

This work reports the morphology and physical properties of silane-grafted polypropylene (PP-g-VTEOS) reinforced with silica nanoparticles and toughened with an elastomeric ethylene-octene copolymer (POE). Vinyltriethoxysilane (VTEOS) was grafted to polypropylene (PP) to form (PP-g-VTEOS), using a peroxide-initiated melt compounding technique. TEM observations of composites containing up to 7 wt% of the nanosilica revealed good dispersion of the silica nanoparticles, which partitioned selectively within the PP-g-VTEOS matrix. Rheological characterization in the linear viscoelasticity region showed significant increases in the low-frequency complex viscosity, storage and loss moduli, which stem from the polymer/filler and filler/filler interactions. The effects of surface treatment of the nanosilica on the morphology, thermal and mechanical properties of the composites were also investigated. The mechanical properties of the composites were greatly enhanced in terms of tensile and flexural strength, while impact strength was preserved when the silane-treated nanosilica was used.