PBT/PVA复合纳米纤维膜的制备及性能研究

通过将聚乙烯醇(PVA)与聚对苯二甲丁二醇酯(PBT)不同比例混合进行静电纺丝,对所得PBT/PVA复合纳米纤维膜通过扫描电子显微镜(SEM)、单轴拉伸测试以及水接触角测试进行了表征。结果显示:PBT/PVA混合溶液的可纺性和所得纤维膜形貌随PVA含量增加而变化;纯PBT纳米纤维膜表现为较低的力学性能和疏水性(水接触角为135°),而少量PVA的混入(PBT/PVA=20/1或10/1)可以有效提高所得纤维膜力学性能和亲水性,尤其10/1的PBT/PVA复合纤维膜在力学性能提高的同时表现为超亲水特性(水接触为0°)。     

无机纳米粒子原位复合聚氨酯研究

将纳米二氧化硅 (SiO2 )经预分散后加入聚氨酯 (PU)反应体系进行原位聚合。结果表明所得PU有较好力学性能。透射电镜 (TEM )照片显示纳米SiO2 在PU中基本上达到纳米分散     

纳米SiO2增韧增强氰酸酯制备工艺的研究

从纳米SiO2三种不同的分散工艺(研磨法、偶联剂表面处理法和高速均质剪切法)着手,通过原位聚合法制得SiO2/氰酸酯(CE)纳米复合材料;采用透射电镜分析(TEM)、扫描电镜分析(SEM)和热失重分析(TGA)研究了三种分散工艺对纳米SiO2的分散以及复合材料的力学性能和热性能的影响.结果表明,研磨对纳米SiO2的分散优于高速均质剪切,偶联剂表面处理分散较差;高速均质剪切对复合材料力学性能和热性能的提高程度优于研磨法,当纳米SiO2含量为1phr时,高速均质剪切所得复合材料的冲击强度和弯曲强度分别比纯CE提高35.0%和12.1%;当质量损失为5%时复合材料的热分解温度较纯CE提高23.8℃;偶联剂表面处理法则降低了复合材料的弯曲强度和热分解温度.     

纳米SiO2改性环氧树脂及其复合材料性能研究

先采用机械搅拌和超声分散方式在环氧树脂中分散纳米SiO2微粒,通过扫描电镜表征断面的形貌来分析纳米SiO2分散效果,再采用力学性能测试,研究纳米SiO2对环氧树脂及其玻璃纤维增强复合材料性能的影响,结果表明,超声分散效果明显优于机械搅拌分散;纳米SiO2含量对分散效果、环氧树脂及其复合材料力学性能具有显著影响;采用超声分散的1%(质量分数)纳米SiO2改性环氧树脂浇铸体的弯曲强度比未改性的提高了21.2%,其玻璃纤维增强复合材料的弯曲和拉伸强度分别提高了9.7%和7.9%,但层间剪切强度则降低了10.6%。     

纳米SiO2改性生物降解复合薄膜研究

目的以壳聚糖(chitosan)、木薯淀粉和聚乙烯醇(PVA)为基础成膜原料,探究纳米SiO2改性木薯淀粉/PVA/壳聚糖薄膜的制备工艺过程。方法以薄膜断裂伸长率、抗张强度、透光率和吸水率为评判标准,在单因子试验基础上,设计L9(34)正交试验,研究纳米SiO2含量、分散剂十二烷基苯磺酸含量、膜液pH值等3个因素对纳米SiO2改性木薯淀粉/聚乙烯醇/壳聚糖薄膜性能的影响。结果得出了制备纳米SiO2改性木薯淀粉/PVA/壳聚糖薄膜的最佳工艺参数,纳米SiO2质量分数为2.0%、十二烷基苯磺酸钠质量分数为2.0%、膜液pH值为3.0,3个因素对改性薄膜性能的影响程度大小排序为分散剂含量纳米SiO2含量pH值。结论获得了纳米SiO2改性木薯淀粉/PVA/壳聚糖薄膜的最佳生产工艺参数。     

纳米SiO2/环氧树脂灌封材料的研究

以纳米SiO 2作为增强材料,制备了纳米SiO2/环氧树脂灌封材料,并研究了不同的纳米含量对灌封材料性能的影响,采用透射电镜(TEM)对纳米SiO2粒子分散情况进行了分析.结果表明,纳米SiO2均匀地分散在环氧树脂基体中,有效地改善了环氧树脂的力学性能,并且当纳米SiO2含量为3%时,纳米SiO2/环氧树脂灌封材料的力学性能最佳,其冲击强度和弯曲强度比环氧树脂分别提高98%和112%,同时电学性能也有所提高.     

纳米SiO_2/纤维素包装薄膜结构形态及性能研究

采用具有活性基团的硅烷偶联剂KH550(γ-氨丙基三乙氧基硅烷)对纳米SiO2粒子的表面进行改性。以NMMO为溶剂,以纤维素为原料,并向铸膜液中添加改性纳米SiO2,制备改性纳米SiO2/纤维素膜。采用原子力显微镜(AFM)观察了改性纳米SiO2/纤维素薄膜的表面形态,结合电子显微镜(SEM)观察其断面结构,并测定了薄膜的力学性能和透氧透湿性能。实验结果表明:改性后的SiO2较好的在铸膜液中分散,当SiO2粒径为30nm,添加量为2%,偶联剂用量为5%时,纳米复合纤维素膜的各项性能达到最佳。     

乙烯醋酸乙烯酯共聚物与纳米SiO2颗粒复合物的制备方法研究

采取熔融共混方法制备乙烯醋酸乙烯酯共聚物(EVA)和纳米SiO2颗粒的复合体系.通过力学性能测试和材料断面的形貌分析,选取最佳的分散工艺后,进一步表征纳米SiO2在基体中的分散状态及复合物的结构变化.结果表明,3种工艺都能不同程度提高复合物的力学性能,其中一步法对力学性能贡献最大,当纳米SiO2含量为1%时,其复合物的力学性能提高最多.此外,纳米SiO2微粒在EVA基体中的分布粒径＜100nm,纳米SiO2与乙烯基三乙氧基硅烷、EVA之前形成了新的键合结构.     

PES／纳米SiO2杂化膜的成膜机理及性能研究

利用湿法相转化方法，通过在聚醚砜（PES）铸膜液中添加适量的纳米粒径的SiO2，制得了具有不同含量纳米SiO2的PES／SiO2杂化膜。对分相过程中的成膜动力学、膜的微观结构以及性能进行了分析测试，结果表明与纯PES相比，铸膜液中添加了4wt％纳米SiO2后，PES体系的成膜速度有所提高。膜断面的SEM照片表明，PES／SiO2杂化膜有更大的指状孔。膜性能测试结果表明，体系中SiO2含量对PES杂化膜的纯水通量和截留率有影响，在添加的纳米SiO2的含量较少时，所得PES杂化膜的截留率明显升高，水通量则相反而有所降低；随着体系中SiO2含量的进一步增加，PES／SiO2杂化膜的水通量明显增大，同时增强的截留率也得到了保持。     

纳米填料填充辐射硫化三元乙丙橡胶的力学性能及分散形态

采用60Co γ射线作为辐射硫化的辐照源,制备了以纳米二氧化硅(SiO2)、纳米碳酸钙(CaCO3)等为填料的三元乙丙橡胶(EPDM).研究了多官能团单体(PFM)、纳米填料的种类、用量等因素对橡胶力学性能的影响,并考察了纳米粒子在辐射硫化胶中的分散形态.力学性能和扫描电镜结果表明,辐射硫化胶的力学性能与纳米粒子在胶中的分散尺寸和均匀性有关.纳米SiO2粒子以较小尺寸均匀分布在硫化胶中,它对辐射硫化三元乙丙橡胶有较好的补强效果;而采用CaCO3或者二者的混合物为填料,粒子在硫化胶中的分散尺寸相对较大,因而所得辐射硫化胶力学性能不理想.     

聚氯乙烯/聚醚砜共混小孔超滤膜的研制

聚氯乙烯与聚醚砜属部分相容体系。采用溶胶-凝胶相转化法,改变聚合物共混比例、混合溶剂、添加剂用量,制备了一系列聚氯乙烯/聚醚砜(PVC/PES)共混超滤膜。通过调配铸膜液中聚合物共混比例,可大大提高共混膜的强度和韧性。其水通量和截留率与同类日本产高分子分离膜相比,均有较大提高。     

CaCl2对聚丙烯腈超滤膜性能的影响

在PAN／DMAC体系里，研究了添加剂CaCl2对聚丙烯腈超滤膜性能的影响，通过膜的纯水通量，切割分子量曲线以及场发射扫描电镜对所制得的膜进行了表征及研究．与无添加剂的PAN／DMAC体系相比，CaCl2的加入降低了膜液的黏度，提高了膜的纯水通量，而对膜的切割分子量无明显的影响．     

聚醚酰亚胺中空纤维超滤膜的研究（I）膜结构、热性能和机械性能

以聚醚酰亚胺（PEI）为膜材料,聚乙烯吡咯烷酮（PVP）和聚乙二醇（PEG）等添加剂,N－甲基吡咯烷酮（NMP）和二甲基乙酰胺（PMAc)为溶剂,采用干／湿法纺丝技术制备出聚醚酰亚胺中空纤维膜,提高了PEI超滤膜的耐污梁性,通过改变纺丝液中不同的添加剂（如PEG或PVP）,PEI中空气纤维膜断面可从指状孔转变成海绵状,此外,讨论了聚醚酰亚胺中空纤维的膜结构,热性能和机械性能。     

Structure-property relationship in sol-gel derived polymer/silica hybrid nanocomposites prepared at various pH

This paper reports a comparative study on structure-property relationship of acrylic rubber (ACM)/silica, epoxidised natural rubber (ENR)/silica and poly (vinyl alcohol) (PVA)/silica hybrid nanocomposites prepared by sol-gel technique under different pH levels (pH = 1.0–13.0), probably for the first time. The initial concentration of tetraethoxysilane (TEOS) (used as the precursor for silica) was kept at 45 wt%, and tetrahydrofuran (THF) for ACM/silica and ENR/silica while water for PVA/silica were taken as solvents. TEOS to water mole ratio was maintained at 1:2 for the rubber/silica systems to accomplish the sol-gel reaction. The structure of the resultant hybrid composites was determined by using electron microscopy, Fourier Transform infrared spectroscopy and solubility. Dynamic mechanical and mechanical properties were also investigated. The silica particles were found to exist as nanoparticles (average diameter <100 nm) at low pH (≤ 2.0) beyond which these aggregate, although the amount of silica generation was not strictly influenced by the various pH conditions in all the systems. These nanocomposites were optically clear and showed superior mechanical reinforcement over the micro-composites containing aggregated silica structures with lower optical clarity. The nanocomposites exhibited higher storage modulus both at the glassy and the rubbery regions as compared to those micro-composites. The loss tangent peak heights were also minimum and the Tg shifted to higher temperature for those nanocomposites. The maximum improvement of mechanical properties was observed with the PVA/silica nanocomposites due to higher level of interaction between the hydroxyl groups of PVA and the silanol groups of the silica phase.     

纳米纤维素晶/醋酸纤维素共混超滤膜材料的研究

采用浸没沉淀相转化法制备了纳米纤维素晶(CNC)/醋酸纤维素(CA)完全环境友好的共混膜材料,考察了在铸膜液中添加不同质量分数的CNC对共混膜各方面性能的影响。通过超滤装置测定了共混膜的水通量、截留率、含水率和孔隙率;通过万能试验机、环境扫描电子显微镜(SEM)、热重分析仪(TGA)对超滤膜进行了力学性能、形貌结构和热稳定分析。结果表明,随着CNC含量增加,共混膜的孔隙率呈增长趋势,由40.8%提高到66.4%,大孔由原来的规则圆形漏斗状变为狭长椭圆状且互相连通,水通量和拉伸强度呈先上升后减小的趋势。当CNC添加量为0.5%时,共混膜综合性能最优,相比纯CA膜,水通量提高64.7%,拉伸强度提高70%,热稳定性也得到增强。     

Self‐Healing Proton‐Exchange Membranes Composed of Nafion–Poly(vinyl alcohol) Complexes for Durable Direct Methanol Fuel Cells

Proton‐exchange membranes (PEMs) that can heal mechanical damage to restore original functions are important for the fabrication of durable and reliable direct methanol fuel cells (DMFCs). The fabrication of healable PEMs that exhibit satisfactory mechanical stability, enhanced proton conductivity, and suppressed methanol permeability via hydrogen‐bonding complexation between Nafion and poly(vinyl alcohol) (PVA) followed by postmodification with 4‐carboxybenzaldehyde (CBA) molecules is presented. Compared with pure Nafion, the CBA/Nafion–PVA membranes exhibit enhanced mechanical properties with an ultimate tensile strength of ≈20.3 MPa and strain of ≈380%. The CBA/Nafion–PVA membrane shows a proton conductivity of 0.11 S cm^?1 at 80 °C, which is 1.2‐fold higher than that of a Nafion membrane. The incorporated PVA gives the CBA/Nafion–PVA membranes excellent proton conductivity and methanol resistance. The resulting CBA/Nafion–PVA membranes are capable of healing mechanical damage of several tens of micrometers in size and restoring their original proton conductivity and methanol resistance under the working conditions of DMFCs. The healing property originates from the reversibility of hydrogen‐bonding interactions between Nafion and CBA‐modified PVA and the high chain mobility of Nafion and CBA‐modified PVA.     

淀粉/PVA复合膜的制备及血液相容性

在无化学处理的条件下制备出淀粉/聚乙烯醇(PVA)复合膜, 进行了力学性能、 溶胀度及红外光谱测试, 并通过溶血试验、 动态凝血试验、 血小板消耗试验对复合膜的血液相容性进行了表征。研究结果表明, 通过共混改性把淀粉引入到PVA中, 改善了力学性能和血液相容性。当PVA与淀粉的质量比为4∶1时, 复合膜的抗拉强度为13.73 MPa, 抗拉应变率为43.07%, 性能最佳。      

具有催化与渗透汽化双功能的纳米TiO2和Al2O3填充复合膜性能

采用聚丙烯腈(PAN)中空纤维超滤膜作为支撑底膜,经戊二醛(GA)表面交联的聚乙烯醇(PVA)作为渗透汽化层,以及纳米TiO2或Al2O3填充的全氟磺酸树脂(PFSA)作为催化层,制备了催化与渗透汽化双功能复合膜,考察了其亲水性能、对乙酸乙酯塔顶粗酯的渗透汽化分离性能、催化酯化反应性能以及机械性能.实验结果表明:催化与渗透汽化双功能复合膜具有良好的亲水性和机械性能,渗透通量可达到179g/(m2.h),相对应的分离系数为95,渗透物中不含乙酸乙酯,同时可显著缩短酯化反应达到相同转化率的时间.     

NaA分子筛改性聚砜超滤膜的通量及截留性能

利用溶液相转化法,在铸膜液中加入分子筛NaA和PEG来协同提高聚砜超滤膜的水通量和截留率,研究了分子筛的含量对聚砜超滤膜的形貌结构,表面粗糙度,水通量,蛋白质截留率和亲水性的影响。利用场发射扫描电镜、扫描探针原子力显微镜、膜评价仪和接触角仪分别对该膜的形貌、水通量、蛋白质截留率和亲水性进行表征。结果表明分子筛含量从0g增加到3.0g,聚砜超滤膜的水通量从140L/(m2·h)提高到500L/(m2·h),对胃蛋白酶的截留率从78.8%提高到92.7%,对牛血清蛋白的截留率从97.6%增加到99.0%以上。分子筛NaA可以协同提高聚砜超滤膜的水通量和蛋白质截留率。     

Silica ceramic nanofiber membrane with ultra-softness and high temperature insulation

Silica ceramic nanofiber (SCNF) membranes with ultra-softness were fabricated by electrospinning and precursor derived ceramic technology. Firstly, the precursor fiber membrane was obtained by electrospinning from spinnable precursor sol, which was prepared by using silica sol as raw material and polyvinyl alcohol (PVA) as spinning aid, and after heat treatment, it was converted into the SCNF membrane composed of pure inorganic components, which had the ultra-softness to restore the original shape after arbitrary folding. Then the effects of different PVA dosages and heat treatment temperatures on the fiber morphology, thermal stability, mechanical properties, and thermal conductivity of SCNF membranes were investigated. Among all the membranes, the SCNF membrane that was made with a precursor sol of 5% PVA and sintered at 900 °C (Ss?+?PVA 5%-900 °C) showed the smoothest as well as the most uniform fiber morphology, with an average fiber diameter of 285.19 nm, a density of 0.106 g cm^?3, the best mechanical properties (tensile strength of 4.145 MPa), and it also had the lowest thermal conductivity of 0.05285 Wm^?1 K^?1. The Ss?+?PVA 5%-900 °C SCNF membrane still maintained intact fiber morphology after being treated at 1200 °C. These excellent properties make the SCNF membrane have a potential application prospect as an insulation material in ultra-high temperature environments.