TiO2改性PC纳米纤维增强PMMA透光复合材料

利用同轴共纺技术制备出壳（聚甲基丙烯酸甲酯,PMMA）－芯（聚碳酸酯,PC）复合纳米纤维,再通过热压将壳层熔融后得到PC纳米纤维增强PMMA透光复合材料. 分别在复合纳米纤维的壳层或芯层中添加不同含量的纳米二氧化钛（TiO₂）粒子,观察纳米颗粒在复合纤维不同结构中的分布,并分析其含量及分布状态对透光复合材料的可见光透过率、紫外光透过率以及力学性能的影响. 研究结果表明,分布在壳层的纳米TiO₂可明显提高复合材料的紫外光屏蔽性,拉伸性能得到增强,但是透光率有所下降;分布在芯层的纳米TiO₂对复合材料的透光率影响较小,而对拉伸性能的提高较引入壳层的效果更为显著.     

TiO2/ACF复合材料的Sol-Gel法制备及其对苯的去除性能

以钛酸四丁酯为钛源,采用改进溶胶凝胶法合成TiO₂前驱体;采用浸渍提拉法将TiO₂前驱体负载在活性炭纤维(ACF)表面制得TiO₂/ACF复合材料.采用X射线衍射（XRD）、扫描电镜（SEM）、低温液氮吸附等对TiO₂/ACF复合材料晶相结构、表面结构等进行了表征.在静态自制光催化反应装置中紫外光照射条件下,以高浓度（2926.5mg/m³）气态苯考察TiO₂/ACF对气相有机污染物的去除性能,以气相色谱质谱（GC-MS）检测中间产物种类与分布.结果表明：TiO₂于ACF表面形成完整薄层,随负载次数增加,TiO₂/ACF比表面积下降;TiO₂薄层变厚、开裂,甚至脱落.400 ℃煅烧时TiO2已完全转变为锐钛矿相,随煅烧温度升高,锐钛矿型TiO₂晶粒尺寸变大,至700℃时开始有金红石相生成.负载2次,400 ℃煅烧TiO₂/ACF复合材料TiO₂/ACF-400-2表现出最高活性.TiO₂/ACF对苯的去除过程中未检测到毒性较大的酚、醌类中间产物.     

纳米TiO2/Sb2O5涂层的光生阴极保护研究

采用溶胶凝胶法在304不锈钢表面制备了纳米TiO₂/Sb₂O₅叠层涂层. 用扫描电子显微镜（SEM）、X射线衍射（XRD）、X射线光电子能谱(XPS)对涂层表面形貌、晶体结构以及组成进行表征. 采用电化学方法研究涂层的光电化学性能与光生阴极保护特性. 结果表明,所制备的纳米TiO₂/Sb₂O₅叠层涂层表面连续、均匀、致密;XRD分析表明纳米TiO₂为锐钛矿型;XPS分析表明纳米涂层表面与内层均由Ti、Sb、O、C四种元素组成;稳定电位与极化曲线测试表明,在3%NaCl溶液中,纳米TiO₂/Sb₂O₅叠层涂层的光电化学性能低于纯纳米TiO₂涂层,但纳米TiO₂/Sb₂O₅涂层经紫外光照1h,停止紫外光照后的延时阴极保护作用可达4h. 通过研究分析,提出了一种新的纳米叠层涂层光生阴极保护作用机理.     

多孔SiO2与TiO2复合纳米材料的制备及光催化性能

在溶胶水热法所合成的锐钛矿相TiO₂纳米晶基础上,利用模板剂调制的SiO₂溶胶进一步合成了多孔SiO₂与TiO₂复合纳米粒子,重点研究了复合SiO₂对纳米锐钛矿相TiO₂热稳定性及光催化活性的影响.结果表明,复合SiO₂提高了纳米锐钛矿相TiO₂的热稳定性,经过900℃热处理后的TiO₂仍然具有以锐钛矿相为主的相组成.在光催化降解罗丹明B实验过程中,经过高温热处理的复合纳米材料表现出优于Degussa P25 TiO₂的活性,这主要与其锐钛矿相结晶度提高和具有较大比表面积等有关.     

铝硅酸盐中间体对TiO2纳米粒子团聚及相转变的抑制

以粉煤灰为原料, 通过与NaOH煅烧、水解合成铝硅酸盐中间体(ASI), 向sol-gel法制备的TiO₂溶胶中加入ASI, 经处理得到钛铝硅酸盐复合材料(TiO₂/ASI). X射线衍射分析(XRD)和紫外-可见漫反射光谱(DRS)研究ASI对sol-gel方法制备TiO₂纳米晶形成过程和相转变的影响. 研究结果表明: 铝硅酸盐中间体不但能抑制TiO₂纳米粒子的团聚, 而且能够有效地抑制TiO₂由锐钛矿型向金红石型的相转变, 由此所制备TiO₂与ASI的钛铝硅酸盐复合材料(TiO₂/ASI)对溶液中亚甲基蓝的吸附性能高于单一的TiO₂或铝硅酸盐中间体.     

水热法制备过程中TiO2纳米纤维成形机理研究

采用水热法制备出φ20～30nm, 长度达微米级的TiO2纳米纤维, 以XRD、TEM、IR等手段对不同工艺条件下获得的产物晶型结构、微观形貌以及化学组成进行了表征, 对TiO₂纳米纤维成形机理进行探讨, 并就洗涤过程中pH值对纤维结构的影响进行分析. 结果表明, TiO₂纳米纤维的形成机理可能是锐钛矿型TiO₂纳米颗粒在强碱作用下生成K₂Ti₆O₁₃颗粒, 小颗粒沿一定晶轴生长, 遵循溶解-生长机理, 逐渐长成纳米纤维. 清洗溶液的pH值对产物的成分和结构有较大影响, 通过控制清洗溶液的pH值和热处理温度, 可以获得组成分别为K₂Ti₆O₁₃、H₂Ti₃O₇和TiO₂的纳米纤维. 在pH=7、80℃烘干条件下得到的主要是H₂Ti₃O₇纳米纤维, 400℃煅烧后转变为TiO₂纳米纤维.     

掺杂基团对氮改性TiO2紫外光催化活性影响的机理研究

以TiCl₄为钛前驱体,采用沉淀法制备了氮掺杂和纯TiO₂. X射线衍射（XRD）和N₂吸附－脱附等温线表征结果表明：所制催化剂以锐钛矿相为主,具有介孔结构. X射线光电子能谱（XPS）证实掺杂的氮以系列NO_x存在. 由紫外－可见漫反射吸收光谱（UV-Vis）可知：氮掺杂TiO₂ ( N-TiO₂ )在400～550nm的可见光区出现新的吸收带. 4-氯苯酚(4-CP)降解实验表明,N-TiO₂的紫外和可见光催化活性均高于纯TiO₂. N-TiO₂具有较高紫外光活性的原因可归于催化剂中含有的NO_x. NO_x在不改变TiO₂禁带宽度的情况下,拓展了它的感光范围,激发更多的光生电子和空穴参与反应,并可降低电子和空穴的复合几率,从而提高了催化剂的紫外光活性.     

包覆型高岭土/二氧化钛纳米复合颗粒的电流变效应

采用溶胶-凝胶法制备了一种新型高岭土/二氧化钛纳米复合电流变液材料.XRD、FT-IR、SEM分析表明TiO₂以纳米晶的形态包覆于高岭土表面.电流变性能测试表明,不同的TiO₂质量比的复合颗粒电流变液效应不同,且都比纯高岭土电流变有显著提高.同时当复合颗粒中TiO₂质量百分比在34％,颗粒硅油体积分数为25％,直流电场为3kV/mm时,高岭土/二氧化钛纳米复合材料电流变液的静屈服应力达3.4kPa,是纯高岭土电流变液的5倍.     

负载TiO2的硅藻土对亚甲基蓝的光降解性能研究

硅藻土是一种天然生物成因的SiO₂. 采用硅藻土做载体,用溶胶-凝胶法制备TiO₂/硅藻土复合光催化剂,TiO₂呈薄膜状负载在硅藻土上,部分团聚成颗粒状. 在紫外光条件下负载TiO₂硅藻土对亚甲基蓝具有良好的光催化降解性能,36h后对亚甲基蓝的脱除率为90％, 48h达到98％, 降解效果好. 纯硅藻土48h后对亚甲基蓝的脱除率仅为35％左右. 负载TiO₂硅藻土对亚甲基蓝的光降解性能受TiO₂的同质多像结构影响. 随着锐钛矿含量增加, 负载TiO₂硅藻土的光降解性能增强. 但是, 当温度进一步升高, TiO₂由锐钛矿型转化为金红石型, 负载TiO₂硅藻土的光降解性能随之降低. 添加H₂O₂明显提高亚甲基蓝溶液的降解效果.     

HNO3处理对TiO2纳米薄膜的光催化活性和表面微结构的影响

通过sol-gel工艺分别在钠钙玻璃和预涂SiO₂涂层的钠钙玻璃基体上制备了TiO₂。光催化纳米薄膜.然后用1mol/L HNO₃水溶液对煅烧后的薄膜进行酸处理.用X射线光电子能谱(XPS)、扫描电镜(SEM)和紫外可见光谱(UV-VIS)对酸处理前后TiO₂纳米薄膜进行了表征.用甲基橙水溶液的光催化脱色来评价TiO₂薄膜的光催化活性.结果表明:SiO₂涂层能有效阻止钠离子从玻璃基体向TiO₂薄膜的扩散;普通玻璃表面的TiO₂纳米薄膜经HNO₃处理后,薄膜的光催化活性明显增强.这是由于TiO₂纳米薄膜中的钠离子浓度降低以及表面羟基含量增加的缘故.     

PA6(MWNTs)纳米纤维增强PMMA透光复合材料

以尼龙6(PA6)为载体,结合同轴共纺技术将多壁碳纳米管(MWNTs)均匀包裹在PA6/PMMA体系的芯层中,再利用热压成型技术将壳层聚甲基丙烯酸甲酯(PMMA)熔融,从而制备出PA6(MWNTs)均匀分散的增强透光复合材料.实验中分别考察不同含量的MWNTs对复合材料形貌、力学性能的影响.结果表明,采用同轴共纺工艺能...     

多功能nano ZnO/PMMA复合材料的制备与性能

采用一种简单、环保的方法原位制备了纳米ZnO/聚甲基丙烯酸甲酯（nano ZnO/PMMA）复合材料,并对其抗紫外性质、透明性、光致发光性质和抗菌性进行了研究。以乙醇为溶剂在30℃溶解单体、引发剂、前驱体和催化剂;升温到80℃使甲基丙烯酸甲酯（MMA）的聚合与ZnO的合成同时进行;蒸发去除溶剂即可获得nano ZnO/PMMA复合材料。采用XRD、FTIR、TEM和UV-Vis对nano ZnO/PMMA复合材料进行表征。结果表明,已成功制备nano ZnO/PMMA复合材料;所制备的nano ZnO/PMMA复合材料能够吸收200~400 nm的紫外辐射,且在可见光区域具有高的透明度;光致发光测试表明,nano ZnO/PMMA复合材料在紫外光激发下能够发出明亮的蓝绿光;抗菌测试表明,nano ZnO/PMMA复合材料对金黄色葡萄球菌具有显著的抗菌效果,其抗菌率大于99%。多功能nano ZnO/PMMA复合材料在紫外屏蔽涂层、抗紫外有机玻璃、荧光材料、抗菌塑料制品等诸多领域有潜在应用。     

Optical and mechanical anisotropies of aligned electrospun nanofibers reinforced transparent PMMA nanocomposites

This study aims to assess the nanofiber directionality effects on optomechanical properties of a widely used transparent thermoplastic poly(methyl methacrylate) (PMMA). Aligned fiber-hybrid mats consisted of nylon-6 (PA-6) nanofibers and PMMA microfibers are prepared using a self-blending co-electrospinning method, followed by hot press molding to fabricate into transparent nanocomposites. Effects of nanofiber orientation degree in two orthogonal directions and loading fraction on the optomechanical behavior of the nanocomposites are examined. Optical transmittance differences parallel and perpendicular to the nanofibers’ orientation are found to vary in a range of 3.9–5.4% at 589 nm, and strong mechanical anisotropy is observed with the 1% PA-6/PMMA nanocomposites. A maximal of 3% PA-6 nanofiber loading maintains the nanocomposite high transmittance (>75%) with improved strength and toughness along the nanofiber axis. This study reveals evident anisotropic optomechanical properties of transparent nanocomposites, and highlights the great designability of transparent nanocomposites by using aligned nanofibers as the designing elements.     

纳米ATO/PVB隔热透明原位复合材料的制备及性能

利用超声波将经表面预处理的纳米氧化锡锑(ATO)粒子均匀分散到聚乙烯醇(PVA)水溶液中,与正丁醛缩合反应,原位法制备了一系列纳米ATO/聚乙烯醇缩丁醛(PVB)复合材料。采用FTIR、UV/VIS/NIR、TG、TEM及AFM等对所制备的原位纳米ATO/PVB复合材料的结构、微观形貌及性能进行了研究。结果表明: 在合成PVB树脂的阶段添加少量纳米ATO粒子,能更均匀地分散在PVB基质中,所制备的复合材料薄膜的紫外线及近红外光透过率大幅度下降,而可见光透过率降低幅度较小,且随纳米ATO用量增加,紫外屏蔽及隔热性能不断提高。在纳米ATO用量(与PVB质量比为2.76%)较低时,纳米ATO/PVB复合材料的力学性能尤其韧性得到明显提高,断裂伸长率达到纯PVB的7.3倍; 在ATO与PVB质量比为1.74%时,可见光透过率高于70%,紫外光透过率低于10%,近红外光热辐射透过率低于28%,导热系数为0.23 W(m·K)^-1,与纯PVB相比,用纳米ATO/PVB复合材料胶膜所制盖板的隔热空腔内温度下降5.5℃,具有良好的透明度、紫外屏蔽及隔热性能。     

Electromagnetic interference shielding characteristics of carbon nanofiber-polymer composites

Electromagnetic interference (EMI) shielding characteristics of carbon nanofiber-polystyrene composites were investigated in the frequency range of 12.4-18 GHz (Ku-band). It was observed that the shielding effectiveness of such composites was frequency independent, and increased with increasing carbon nanofiber loading within Ku-band. The experimental data exhibited that the shielding effectiveness of the polymer composite containing 20 wt% carbon nanofibers could reach more than 36 dB in the measured frequency region, indicating such composites can be applied to the potential EMI shielding materials. In addition, the results showed that the contribution of reflection to the EMI shielding effectiveness was much larger than that of absorption, implying the primary EMI shielding mechanism of such composites was reflection of electromagnetic radiation within Ku-band.     

高透明度β-甲壳素纳米纤维薄膜的制备与性能

目的以废弃鱿鱼顶骨为原料,在温和条件下提取并制备高强度、高透明度的β-甲壳素纳米纤维薄膜。方法常温下利用温和提取法,从鱿鱼顶骨中提取β-甲壳素纳米纤维(β-ChNF);通过真空抽滤,制备β-甲壳素纳米纤维薄膜(β-ChNF/m)。并与以蟹壳为原料“高温提取”制备所得的α-甲壳素纳米纤维薄膜(α-ChNF/m)进行对比;通过力学性能、结晶结构、微观构造、表面化学特性及透光性分析,探索“温和条件”提取法对薄膜性能的影响规律。结果利用温和提取法,能最大程度保留β-ChNF在鱿鱼顶骨中的天然纳米形态与性能;与从蟹壳中提取所得α-甲壳素相比,研究制备所得β-ChNF/m比α-ChNF/m力学强度提高了近1.5倍,断裂伸长率提高了3倍,且具备优异的透光性,透光率为90%,雾度为4%。结论以鱿鱼顶骨为原料制备所得β-ChNF/m具有优异的透光性、力学性能,有望作为柔性电子标签基材应用于智慧包装、包装智能检测等研究领域。     

纳米氧化锑锡增强聚碳酸酯的阻红外隔热性能

为在提高聚碳酸酯(PC)隔热性能的同时保持较高的透明度,以纳米氧化锑锡(ATO)为红外阻隔剂,采用溶胶-凝胶法制备了一系列硅烷偶联剂KH-570改性纳米ATO/PC复合材料。通过激光粒度分布仪和SEM研究了纳米ATO的粒径分布及其在PC基体中的分散情况,采用拉力试验机、分光光度计以及隔热效果模拟装置测定了复合材料的力学性能、透射性能和隔热效果。结果表明:硅烷改性纳米ATO在PC基体中分散均匀;复合材料的拉伸强度和冲击强度分别保持在60.0 MPa和16.0kJ·m-2以上;随着纳米ATO质量分数的增加,纳米ATO/PC复合材料的阻红外隔热性能改善;当纳米ATO含量为0.5wt%时,纳米ATO/PC复合材料的可见光透过率高于80%,隔热效果模拟装置内外温差达3.9℃。     

Synthesis and mechanical properties of interconnected carbon nanofiber network reinforced polydimethylsiloxane composites

Carbon nanofiber (CNF) reinforced elastomer composites with light weight, sustainability of large deformation, chemical stability, corrosion and fatigue resistance, and vibration and noise reduction capability can have positive impact on a wide range of applications. However, this type of composite is still a under studied research area due to the difficulties in material handling and processing. To improve processing control and reproducibility for large scale engineering applications, cost effective carbon nanofibers (CNFs) in form of interconnected porous network structure were used as nanofillers. Processing, microstructure and mechanical properties of carbon nanofibers reinforced polydimethylsiloxane (PDMS) have been studied. Mechanical measurements on the composites show that the CNF-PDMS interfacial bonding can be until failure, interfacial debonding happens in the CNF-PDMS composites and the resulted permanent deformation stabilizes with increasing load-unload cycles with significant energy dissipation.     

A comparative study of EMI shielding properties of carbon nanofiber and multi-walled carbon nanotube filled polymer composites

Electromagnetic interference shielding properties of carbon nanofiber- and multi-walled carbon nanotube-filled polystyrene composites were investigated in the frequency range of 8.2-12.4 GHz (X-band). It was observed that the shielding effectiveness of composites was frequency independent, and increased with the increase of carbon nanofiber or nanotube loading. At the same filler loading, multi-walled carbon nanotube-filled polystyrene composites exhibited higher shielding effectiveness compared to those filled with carbon nanofibers. In particular, carbon nanotubes were more effective than nanofibers in providing high EMI shielding at low filler loadings. The experimental data showed that the shielding effectiveness of the composite containing 7 wt% carbon nanotubes could reach more than 26 dB, implying that such a composite can be used as a potential electromagnetic interference shielding material. The dominant shielding mechanism of carbon nanotube-filled polystyrene composites was also discussed.     

Strong and optically transparent biocomposites reinforced with cellulose nanofibers isolated from peanut shell

Cellulose nanofibers–reinforced PVA biocomposites were prepared from peanut shell by chemical–mechanical treatments and impregnation method. The composite films were optically transparent and flexible, showed high mechanical and thermal properties. FE-SEM images showed that the isolated fibrous fragments had highly uniform diameters in the range of 15–50 nm and formed fine network structure, which is a guarantee of the transparency of biocomposites. Compared to that of pure PVA resin, the modulus and tensile strength of prepared nanocomposites increased from 0.6 GPa to 6.0 GPa and from 31 MPa to 125 MPa respectively with the fiber content as high as 80 wt%, while the light transmission of the composite only decreased 7% at a 600 nm wavelength. Furthermore, the composites exhibited excellent thermal properties with CTE as low as 19.1 ppm/K. These favorable properties indicated the high reinforcing efficiency of the cellulose nanofibers isolated from peanut shell in PVA composites.