STRUCTURE AND PROPERTIES OF COMPOSITE POLYURETHANE HOLLOW FIBER MEMBRANES

Composite polyurethane(PU)-SiO_2 hollow fiber membranes were successfully prepared via optimizing thetechnique of dry-jet wet spinning,and their pressure-responsibilities were confirmed by the relationships of pure water flux-transmembrane pressure(PWF-TP)for the first time.The origin for this phenomenon was analyzed on the basis of membranestructure and material characteristics.The effects of SiO_2 content on the structure and properties of membrane wereinvestigated.The experimental results indicated that SiO_2 in membrane created a great many interfacial micro-voids andplayed an important role in pressure-responsibility,PWF and rejection of membrane:with the increase of SiO_2 content,theability of membrane recovery weakened,PWF increased,and rejection decreased slightly.

Fabrication and characterization of novel foaming polyurethane hollow fiber membrane

Foam-like materials had attracted great interest as promising absorbent. In this study, thermoplastic polyurethane(TPU) block sponge was synthesized. Polyester(PET) braid tubular reinforced polyurethane(PU) spongy hollow fiber membrane was prepared by a concentric circular spinning method. The method was woven from an outer coated water-blown PU separation layer and inner PET braid tubular. We have developed a simple and useful preparation technique for the PU spongy hollow fiber membrane. For the first time, the PU spongy hollow fiber membrane was prepared using a coating and controlled foaming technique. The influence of toluene isocyanate index on the physical properties, morphology, and structure of flexible PU sponge was discussed in terms of water contact angle(CA), pure water flux(PWF), Fourier Transform Infrared Analysis(FTIR),pressure-responsive property, and pull-out strength. The morphologies of the membranes were investigated by scanning electron microscopy. We have characterized the foams from an intuitive point of view and demonstrated that the dimensional morphology of the membrane was closely related to isocyanate index. The result showed that the surface cell size of the PU sponge hollow fiber membrane gradually decreased with an increase of the isocyanate index. Due to the elasticity of PU at room temperature, the pressure responsive characteristic of the membrane was prepared. When isocyanate index was 1.05, the interface bonding strength of PU spongy hollow fiber membranes reached as high as 0.37 MPa, porosity and PWF were 71.5% and 415.5 L·m^-2·h^-1,respectively.

Steam Exploded Peanut Shell Fiber as the Filler in the Rigid Polyurethane Foams

In this study,steam exploded peanut shell fibers(SE-PSFs)were utilized to fabricate with rigid polyurethane foam(RPUF)in order to improve sound absorption performance and hydrothermal weather resistance.Optimized method of SE treatment,RPUF preparation and flame retardant treatment were selected to prepare SE-PSF/RPUF composites in this experiment.Physical and mechanical properties including density,water absorption capacity,thickness swelling rate,compressive strength,thermal conductivity and average sound absorption coefficient of SE-PSF/RPUF were investigated and compared with the control(PRUF).The results showed that the density,water absorption capacity,thickness swelling rate and thermal conductivity showed an increasing trend with the increase of SE-PSFs content.The strength of the composite material showed a downward trend with the increase of the SE-PSFs content.The average sound absorption coefficient of the SE-PSFs/RPUF compared with PRUF significant increased,and the average sound absorption coefficient of the SE-PSFs/RPUF with SE-PSFs 40%was 0.47.The study getted the best ratio of flame retardants for 10%EG and 3%DMMP.The oxygen index was 35.56 vol%.

Mechanical and Thermal Properties of Sugar Palm Fiber Reinforced Thermoplastic Polyurethane Composites:Effect of Silane Treatment and Fiber Loading

The aim of the present study was to develop sugar palm fiber(SPF)reinforced thermoplastic polyurethane(TPU)composites and to investigate the effects of fiber surface modification by 2%silane treatment and fiber loading(0,10,20,30,40 and 50 wt%)on the mechanical and thermal properties of the obtained composites.Surface treatment was employed to improve the fiber-matrix interface,which was expected to boost the mechanical strength of the composites,in terms of tensile,flexural and impact properties.Thermal properties were also investigated by thermal gravimetric analysis(TGA)and dynamic mechanical analysis(DMA)to assess the thermal stability of the developed composites.Furthermore,scanning electron microscopy(SEM)was used to study the tensile fracture samples of composites with a view towards evaluating the effects of fiber surface treatments on the fiber/matrix interfacial bonding.The findings of this study reveal that the silane treatment has determined good bonding and linkage of the cellulose fiber to the TPU matrix,hence contributing to enhanced mechanical and thermal properties of the composites.The composite formulation with 40 wt%sugar palm fiber loading showed optimum values such as 17.22 MPa for tensile,13.96 MPa for flexural,and 15.47 kJ/m^2 for impact strength.Moreover,the formulations with higher fiber content exhibited satisfactory values of storage modulus and thermal degradation,while their good interfacial adhesion was evidenced by SEM images.

Physical and damping properties of kenaf fibre filled natural rubber/thermoplastic polyurethane composites

The paper presents the investigation of the effect of alkaline treatment of sodium hydroxide(NaOH) on physical and dynamic mechanical analysis(DMA) viscoelastic properties of kenaf fibre filled natural rubber(NR)/thermoplastic polyurethane(TPU) composites.The treated kenaf fiber,NR and TPU were weighed and proportioned according to the required compositions and were blended using hot mixed Brabender machine.The polymer composites were then fabricated using the hot press to form a sample board.The sample was cut and prepared and water absorption,density,thickness swelling and DMA tests were performed.As far as physical properties are concerned,composites with the highest NR amount of shows the best results,which indicates good fiber bonding adhesion.The polymer composites with the highest amount of TPU shows the highest damping properties at high temperature.

Compressive and tensile strength of polymer-based fiber composite sand

Traditional soil additives like Portland cement and lime are prone to cause the brittle fracture behavior of soil,and possibly,environmental impacts.This study explores the potential use of polyurethane organic polymer and sisal fiber in improving the mechanical performance of sand.The effects of polymer content,fiber content,and dry density on the unconfined compressive strength(UCS)and direct tensile strength(DTS)of the polymer-fiber-sand composite were evaluated.The results showed significant increase in UCS and DTS of the reinforced sand with the increase of polymer content,fiber content,and dry density.At high dry density condition,a single peaked stress−strain curve is often observed.Higher polymer content is beneficial to increasing the peak stress,while higher fiber content contributes more to the post-peak stress.The combined use of polymers and fibers in soil reinforcement effectively prevents the propagation and development of cracks under the stress.Scanning electron microscopy(SEM)test was also performed to investigate the micro-structural changes and inter-particle relations.It was found through SEM images that the surface coating,bonding,and filling effects conferred by polymer matrix greatly enhance the interfacial interactions,and hence provide a cohesive environment where the strength of fibers could be readily mobilized.

Facile synthesis of a melt-spinnable polyborazine from asymmetric alkylaminoborazine

A novel asymmetric alkylaminoborazine monomer,2-propylamino-4,6-bis（methylamino）borazine,was synthesized for the first time,and directly polymerized to give a melt-spinnable polyborazine（PBN）.This asymmetric alkylaminoborazine was synthesized by an aminolysis reaction of 2,4,6-trichloroborazine（TCB） with different amines under mild conditions.This route turns out to be much cheaper and simpler than the conventional routes.The chemical composition,structure,molecular weights and ceramic yield were investigated by EA,FTIR,NMR,GPC and TG analysis.The PBN exhibits suitable rheological property for melt-spinning, which suggests that it is a potential precursor for BN fibers.

Dynamics Model and Simulation of Polyethylene Terephthalate (PET) Hollow Fiber

On the basis of melt-spinning, the dynamics model of polyethylene terephthalate （PET） hollow fiber is established. The effects of spinning conditions on hollow ratio are discussed and verified. Because of the different quenching conditions, there exist differences of the hollow ratio and the vitrification distances between different cycles. The important role of the quenching conditions on the meltspinning of PEr hollow fiber is also mentioned.

玄武岩纤维对聚氨酯改性沥青混合料水稳定性提升研究

为解决聚氨酯改性沥青混合料水稳定性不良的缺陷,通过浸水马歇尔试验、冻融循环条件下的劈裂试验、低温弯曲试验,研究不同玄武岩纤维掺量下聚氨酯改性沥青混合料的抗水损害能力。结果表明:在冻融循环作用下,玄武岩纤维降低了沥青混合料水损作用造成的空隙率变化,增强了沥青间的粘附性,当纤维掺量为0.3%时,其提升作用最强,残留稳定度和劈裂强度比分别提升了10.9%、32.3%,有效降低了冻融循环引起的弯拉强度与弯拉应变的下降速率,增强沥青混合料之间的粘结力,聚氨酯沥青混合料的水稳定性能得到提高。

塑胶跑道用超细纤维聚氨酯合成革的制备及性能测试

为改善塑胶跑道综合应用性能,优化超细纤维聚氨酯合成革物理机械性能,本文由聚氨酯树脂含浸无纺布制备了超细纤维聚氨酯合成革,并对其力学性能与卫生性能进行了测试表征。结果发现,随着聚氨酯浸渍率增加,超细纤维聚氨酯合成革基布表观密度增大,密实程度提高,而压缩弹性率先增加后减少;随着聚氨酯浸渍率增加,超细纤维聚氨酯合成革基布剥离强度逐渐升高,拉伸强度、断裂伸长率皆呈现先降低后升高再降低的曲线形态,而撕裂强度则表现为先降低后升高的态势;随着聚氨酯浸渍率增加,超细纤维聚氨酯合成革基布透气性与透水汽性持续性下降;超细纤维聚氨酯合成革基布的干擦与湿擦色牢度均可达到5,而于氢氧化钠溶液中不溶色,表明基布耐碱性良好。

运动鞋用水性聚氨酯超细纤维合成革贝斯的制备及性能研究

为了有效解决运动鞋制造领域用溶剂型聚氨酯浸渍制备超细纤维合成革贝斯的污染问题与溶剂残留超标问题,本文基于水性聚氨酯以水为介质,且环保、无毒、不燃、气味小等特性,以浸渍工艺制备了运动鞋用水性聚氨酯超细纤维合成革贝斯,并对其性能进行了测试表征。结果发现,随着水性聚氨酯含量的增加,浸渍合成革贝斯减量、厚度与表观密度皆显著增大,柔软度明显变差,吸水度与透气性先降低后升高,透水汽性变化不显著,拉伸强度与断裂伸长率变化不明显,撕裂强度减小;相较于溶剂型聚氨酯浸渍,水性聚氨酯浸渍超细纤维合成革贝斯减量率相对偏低,力学性能相对较差,厚度、表观密度、柔软度、吸水度、透气性及透水汽性皆显著提高;溶剂型聚氨酯浸渍超细纤维合成革贝斯表面纤维蓬松,手感良好,但孔洞较多,水性聚氨酯浸渍超细纤维合成革贝斯表面纤维呈束状,手感稍显粗糙,但孔洞较少,整体更显丰满。

电化学氧化/硅烷偶联剂处理碳纤维表面增强聚氨酯基复合材料的性能研究

通过两步法制备了改性碳纤维/聚氨酯复合材料。探究了电化学氧化处理法与表面涂层法相结合的一种新型改性方法对碳纤维增强聚氨酯基复合材料性能的影响。通过对碳纤维进行电化学氧化在表面引入含氧官能团,改善碳纤维表面活性。随后向电化学氧化改性的碳纤维施加硅烷偶联剂溶液,在修复碳纤维表面损伤的同时通过化学反应将碳纤维与聚氨酯桥接在一起,提高碳纤维与聚氨酯界面结合性能。结果表明:经电化学氧化/硅烷偶联剂处理后的复合材料对比原始碳纤维聚氨酯复合材料及仅电化学氧化碳纤维聚氨酯复合材料抗拉性能分别提高了83.5%与73.5%,力学性能提升显著。

聚氨酯上浆剂处理PBO纤维复合材料的界面性能

为了提高聚对苯撑苯并二噁唑(poly-p-phenylenebenzobisoxazole,PBO)纤维/环氧树脂复合材料的界面性能,采用γ-氨丙基三乙氧基硅烷(KH550)改性水性聚氨酯得到上浆剂,然后对酸化后的PBO纤维进行表面涂覆处理。采用XPS和EDS分析PBO纤维表面的化学组成,利用SEM研究PBO纤维表面及其复合材料撕裂面的形貌,并对PBO纤维的单丝及复合材料的力学性能进行分析。结果表明:经过上浆剂包覆的PBO纤维表面活性基团明显增多,表面O/C(原子比)由0.16提升至0.25,上浆剂能有效修复纤维表面的缺陷;通过调控纤维表面上浆剂含量和结构,可使PBO纤维/环氧树脂单向复合材料的层间剪切强度提高到41.3 MPa,拉伸强度增加到1.70 GPa,相较于未处理的复合材料分别提高了44.9%和15.6%。

大丝束碳纤维复合材料在风电叶片的应用

大功率风电机组尤其是海上风电大尺寸复合材料叶片对于材料的强度、耐疲劳性能及长期使用可靠性提出了更高的要求,高强度高刚度碳纤维增强复合材料拉挤板材为大尺寸风电叶片主梁结构提供了最佳解决方案。国产低成本大丝束碳纤维生产技术突破为碳纤维增强复合材料风电板材规模化应用奠定了基础,碳纤维/玻璃纤维(碳玻)混杂成型技术、碳纤维/聚氨酯体系拉挤成型技术为风电板材提供了更多可供选择的技术途径。本文结合上海石化48K大丝束碳纤维在风电领域应用研究成果及国内外风电板材新型技术进展,总结了大丝束碳纤维复合材料在风电叶片板材的应用途径。

椰棕基硬质聚氨酯泡沫的制备及其性能

利用微波辅助液化技术将椰棕粉末进行液化制得液化物,以液化物为原料、三乙烯二胺(TEDA)和异辛酸锡(TECH)为复合催化剂、水为发泡剂,与多苯基甲烷多异氰酸酯反应通过一步法制备了硬质聚氨酯泡沫(PURF)。对水发泡制备PURF的条件进行优化,较优的制备条件为催化剂中TEDA和TECH的质量比为4:5、催化剂质量分数为5%、泡沫稳定剂M-8818质量分数为2.5%、发泡剂质量分数为2%,该条件下制备的PURF的压缩强度为223 kPa,超过了大部分生物基PURF。采用傅里叶变换红外光谱对液化物、液化剂和PURF进行表征,通过扫描电镜对泡沫泡孔进行观察。结果显示,所合成的PURF大部分为闭孔,体系中基本没有异氰酸根剩余。使用锥形量热仪对最优PURF进行燃烧行为分析,最大热释放速率(HRR)为250.6 kW/m^(2)。

“沟脊”结构TPU纤维基高灵敏应变传感器的制备

为了提高对微小形变的监测精度,增强柔性应变传感器的灵敏度,制备了一种“沟脊”结构热塑性聚氨酯(TPU)纤维基高灵敏应变传感器。首先在电场和金属电极片阵列接收装置的协同作用下,得到具有模量差异的“沟脊”结构TPU超细纤维基底,随后采用喷涂式层层沉积技术复合导电银层,得到“沟脊”结构TPU纤维基应变传感器。研究表明:“沟脊”结构使得纤维膜的拉伸强度、断裂伸长率提高至13.26 MPa和355.81%,灵敏度在各应变区间均获得数倍增长。“沟脊”结构纤维膜具有正交的纤维排列角度,该种结构不仅可以增强纤维膜的局部应变、诱导表面导电层材料形貌发生较大变化,而且独特的纤维转向将引导产生贯穿型裂纹,引起电阻的急剧增长,灵敏度系数最高可达151.36,同时具有100%的宽工作范围。“沟脊”结构TPU纤维基高灵敏应变传感器在智能可穿戴、医学诊断、人机交互等方面有广阔的应用前景。

纤维含量对汽车内饰用夹层结构植物纤维增强PP复合材料性能的影响

分别以竹纤维(BF)/聚丙烯(PP)复合板、麻纤维(JF)/PP复合板为表层,聚氨酯(PUR)泡沫为芯层,经热压成型制备夹层结构植物纤维/PP复合材料,通过万能力学试验机、导热系数测定仪和驻波管吸声系数测试系统对不同纤维质量分数的夹层结构复合材料进行性能测试及表征。结果表明,PUR夹层结构BF/PP复合材料的力学性能与PUR夹层结构JF/PP复合材料接近,其导热系数≤0.044 W/(m·K),吸声性能良好,燃烧速度≤20.28 mm/min,满足主机厂对汽车内饰构件用材料的要求,且当植物纤维质量分数为40%时,PUR夹层结构植物纤维/PP复合材料的综合性能最佳。

碳纤维圆管增强超弹多孔结构振动特性研究

随着船舶工业技术的快速发展,对动力系统隔振装置提出了更加苛刻的要求,现有的橡胶阻尼材料虽然具备良好的减振效果,但仍然存在着质量大、力学承载性能和吸能性能不足等问题,针对上述背景,将橡胶阻尼材料与力学性能优异的碳纤维圆管相结合设计出了一种兼具轻质、抗冲、隔振的碳纤维圆管增强超弹多孔结构,并在前期的研究中已验证了该结构具有优异的抗冲吸能表现。在此基础上,通过试验结合数值表征的方法研究了该结构的振动行为和减振性能,揭示碳纤维圆管对结构固有振动特性和减振性能的影响规律。结果发现,相比无增强结构,填充碳纤维圆管的超弹多孔结构可在增强结构整体刚度的同时实现减振性能的显著提升;试验结果验证了所建立结构数值模型的可靠性,对比不同增强结构的仿真与试验发现随着碳纤维圆管厚度的增加,结构固有频率呈现先增大后减小的趋势;研究结果可为设计新型轻质高刚度高阻尼结构提供参考。

稻壳/SEBS-g-MAH增强软质聚氨酯泡沫材料性能研究

针对软质聚氨酯泡沫的形态及力学性能存在缺陷的问题,通过添加天然植物纤维填料(稻壳)和马来酸酐接枝苯乙烯-乙烯-丁烯-苯乙烯嵌段共聚物(SEBS-g-MAH),对软质聚氨酯泡沫材料进行了双因素优化对比实验。结果表明:填料会降低软质聚氨酯泡沫材料的表观密度,添加稻壳/SEBS-g-MAH的软质聚氨酯泡沫材料平均表观密度降低了10.3%;稻壳/SEBS-g-MAH添加量为0.5%/2%(均为质量分数)的软质聚氨酯泡沫材料的拉伸性能明显提高,证明了天然植物纤维稻壳与SEBS-g-MAH对聚氨酯发泡具有一定的影响。

阴离子水性聚氨酯上浆剂的制备及其对玻璃纤维性能的影响

上浆是玻璃纤维加工过程中的关键步骤。水性聚氨酯作为玻璃纤维上浆剂具有机械强度高和耐磨性好等优点。以二环己基甲烷二异氰酸酯(HMDI)和聚四氢呋喃醚二醇(PTMEG)为单体,合成了阴离子水性聚氨酯(AWPU),在稀释的AWPU乳液中加入定量硅烷偶联剂KH570制备了玻璃纤维上浆剂。通过傅里叶变换红外光谱仪、热重分析仪对AWPU的官能团、热性能进行表征并测试了其稳定性,研究了AWPU含量对上浆玻璃纤维(SGF)微观形貌、力学性能和集束性能的影响。结果表明:随着上浆剂中AWPU含量的增加,SGF表面越来越光滑;AWPU质量分数在15%~20%时,SGF的机械性能增幅最大;SGF-20断裂强力高达984.528cN,与未上浆玻璃纤维相比断裂强力提高了72.6%,耐磨性能比SGF-15提高了93.2%;SGF-20的集束性能最佳,上浆率达到2.3%。