碳纳米管(CNTs)的改性及其熔纺PLA复合纤维的结构与力学性能研究

首先对碳纳米管(CNTs)进行了强酸改性处理,通过粒径分析仪、FTIR和SEM对改性前后的CNTs进行了表征,分析改性前后CNTs官能团和结构形貌的变化。将改性前后的CNTs分别与PLA在双螺杆挤出机中熔融混合,经过牵伸卷绕装置制备出PLA/CNTs和PLA/M-CNTs(改性后CNTs)复合纤维。利用视频显微镜和单纱强力仪对PLA/CNTs和PLA/M-CNTs复合纤维形貌和性能进行了研究,结果表明:PLA/M-CNTs复合纤维的力学性能较PLA/CNTs复合纤维好。     

无溶剂型纳米SiO2/环氧树脂复合涂料的制备及性能

为了提高环氧树脂涂料的综合性能,以KH-560硅烷偶联剂对纳米SiO2进行原位改性,制备了无溶剂型纳米SiO2/环氧树脂复合涂料。用FT-IR及分散性试验研究了纳米SiO2原位改性的效果;探讨了改性纳米SiO2对复合涂层表面形貌、力学性能、耐紫外光老化性、耐蚀性能的影响。结果表明:KH-560硅烷偶联剂的有机分子链段成功地键合在纳米SiO2粒子表面,改性后的纳米SiO2粒子能均匀地分散在二甲苯中;纳米SiO2能够显著改善环氧树脂涂层的力学性能,当其含量为3%时最好;复合涂层耐紫外光老化及耐腐蚀性比环氧树脂涂层有较大的提高。本无溶剂型纳米SiO2/环氧树脂复合涂层对基材有良好的保护作用。     

改性纳米SiO_2/尼龙复合塑料性能的研究

采用熔融共混法制备改性纳米SiO2/PA6复合塑料,研究了纳米SiO2用量及其粒径对SiO2/PA6复合PA6力学性能、耐热性能和阻隔性能的影响。结果表明:纳米SiO2粒子在纳米SiO2/PA6复合材料中的分散增强了树脂之间的作用力;在一定范围内,随着纳米SiO2用量的增加,改性纳米SiO2/PA6的耐冲击性能、弯曲强度、拉伸强度和耐热性均有一定提高,而纳米SiO2粒径越小,力学性能提高就越显著;当纳米SiO2质量分数为2%~3%时,改性纳米SiO2/PA6透氧性最小,当纳米SiO2质量分数为3%~4%时,改性纳米SiO2/PA6透湿性最小。     

蔗渣纤维表面处理方法对蔗渣纤维/聚乳酸复合材料力学性能的影响

采用了硅烷偶联剂结合碱溶液处理的方法对蔗渣纤维(BF)进行了表面改性, 研究了不同表面处理方法对蔗渣纤维/聚乳酸(PLA)复合材料力学性能的影响, 用SEM对BF处理前后的形貌及复合材料的冲击断面进行了观察。结果表明: 经表面改性的BF都不同程度地改善了BF与PLA基体之间的界面相容性, 其中碱处理后再经偶联剂处理的方法效果最佳, 在40%(质量分数)蔗渣纤维的高填充量下, 复合材料的拉伸强度和冲击强度分别为纯PLA的85.42%和59.74%, 较好地保持了基体PLA的力学强度; 碱处理使BF表面变粗糙、 长径比增大、 比表面积增加, 与PLA的界面粘结加强, 从而有效地提高了BF/PLA复合材料的力学性能。     

蒙脱土的有机改性及其熔纺聚乳酸复合长丝的结构形貌与性能

首先利用十六烷基三甲基氯化铵对蒙脱土(MMT)进行有机改性制得有机蒙脱土(OMT),通过粒径分析仪、FT-IR、XRD和TGA分别对改性前后MMT的粒径大小、官能团变化、结构和热性能进行了表征。然后将MMT和OMT与聚乳酸(PLA)在双螺杆挤出机中熔融混合,经过牵伸卷绕装置制备出PLA/MMT和PLA/OMT复合长丝;利用视频显微镜和单纱强力仪研究了PLA/MMT和PLA/OMT复合长丝的结构形貌和力学性能。结果表明:改性后的MMT与基体有较好的相容性,改善了PLA复合长丝的力学性能。     

利用静电纺丝技术制备纳米黏土/聚乳酸复合纳米纤维与其表征

利用静电纺丝技术制备了纳米黏土/聚乳酸(PLA)复合纳米纤维,并将该复合纳米纤维收集成无纺布薄膜,采用SEM和TEM观察了复合纳米纤维的微观形貌和结构,分别利用XRD和TGA测试了复合纳米纤维的结晶行为及热学行为,并分析了复合纳米纤维薄膜的拉伸力学性能随纳米黏土含量的变化关系。结果表明:当PLA含量为10wt%、纳米黏土含量为1wt%、CHCl3与DMF体积比为3∶1溶剂条件下,所制备的纳米黏土/PLA复合纳米纤维的细度和均匀性均得到改善;XRD测试结果表明,纳米黏土成功附着在PLA中。TGA和力学测试结果表明,纳米黏土/PLA复合纳米纤维的热稳定性和力学性能相对于纯PLA纤维有较大幅度提高,当纳米黏土含量为1wt%时,其初始分解温度提高了60℃,拉伸强度、断裂伸长率和弹性模量分别提高了111.3%、74.9%和20.0%。     

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。     

纳米SiO_2-NaOH-有机硅烷偶联剂表面改性对苎麻纤维/乙烯基酯树脂复合材料性能的影响

为改善苎麻纤维/乙烯基酯树脂复合材料的力学性能和吸湿性能,采用纳米SiO_2联合NaOH和有机硅烷偶联剂KH570对苎麻纤维进行改性,考察了该表面改性方法对苎麻纤维化学结构、表面形貌、结晶度及对苎麻纤维/乙烯基酯树脂复合材料的力学性能和吸水性的影响。结果表明,苎麻纤维表面的胶质被NaOH溶解,纤维吸水性变强,变得疏松,与树脂基体的黏结性增强,纤维结晶度随着碱浓度的增加先升高后降低;有机硅烷偶联剂KH570与苎麻纤维发生偶联作用,静态水接触角增大,疏水性增强,使苎麻纤维/乙烯基酯树脂复合材料界面性能提高;在有机硅烷偶联剂KH570作用下,SiO_2以纳米级尺寸与苎麻纤维表面羟基产生共价键,从而提高了苎麻纤维/乙烯基酯树脂复合材料的力学强度;实验表明,该方法改性后的苎麻纤维/乙烯基酯树脂复合材料吸水率大大降低。     

苎麻织物表面改性对其增强热固性聚乳酸复合材料力学及阻燃性能的影响

采用碱处理、硅烷偶联剂处理、碱+硅烷偶联剂复合处理、碱+阻燃剂+硅烷偶联剂复合处理对苎麻织物进行表面改性,采用模压工艺制备了苎麻织物增强热固性聚乳酸(PLA)复合材料。研究了4种表面改性方法对苎麻织物/PLA复合材料弯曲性能的影响,采用SEM研究了苎麻纤维与PLA基体之间的界面结合状况。结果表明:经过4种表面改性处理后苎麻织物/PLA复合材料的弯曲性能均有所提高,其中碱+硅烷偶联剂复合处理后提高幅度最大,苎麻织物/PLA复合材料的弯曲强度、模量分别提高了59.5%、51.9%。碱+阻燃剂+硅烷偶联剂复合处理后苎麻织物/PLA复合材料的弯曲强度、模量较未处理时分别提高了38.0%、66.8%;且苎麻织物/PLA复合材料60s点火时间的损毁长度为8.25cm,达到了美国DOT/FAA/AR-00/12要求的标准。SEM结果表明:改性处理后苎麻织物/PLA复合材料中纤维与树脂之间的界面结合更好。     

硅烷偶联剂KH-570表面改性纳米SiO2

采用硅烷偶联剂KH-570在酸性条件下对纳米SiO2表面进行改性,并对改性前后的纳米SiO2采用粒径分析仪、傅里叶红外变换光谱仪、紫外-可见光光谱仪、扫描电镜等仪器进行了分析和表征。结果表明,硅烷偶联剂KH-570能成功地对纳米SiO2表面进行改性,使其表面化学键合了硅烷偶联剂的有机官能团,降低了颗粒团聚程度,提高了纳米SiO2在有机介质中的分散程度     

改性纳米二氧化硅/水性聚氨酯杂化皮革补伤剂的制备及表征

以自制聚酯和异佛尔酮二异氰酸酯(IPDI)为原料,添加不同用量的纳米SiO_2,通过物理共混和原位聚合合成不同的水性聚氨酯乳液,并与进口聚氨酯补伤剂A比较。物理共混与原位聚合合成法制得聚氨酯的力学性能、粘数、吸水率、透光率、附着力均与纳米SiO_2的改性方式与用量有关,与进口补伤剂A相比,所得聚氨酯的透光率不足,但附着力要优于进口补伤剂A。通过比较,添加0.10%吐温-80改性纳米SiO_2和一定的助剂,原位聚合制得的纳米SiO_2/水性聚氨酯材料可作为皮革补伤剂。     

The preparation and mechanical properties of novel PVA/SiO2 film

The aim of this work is the evaluation of the mechanical properties of composite PVA/SiO₂. A powder impregnation process with integrated inline continuous plasma of SiO₂ was used to produce PVA/SiO₂ composite. PVA/SiO₂ composite was processed into test laminates by compression mounding and the interface-dominated composite properties were studied. When compared to PVA, the mechanical properties of PVA/SiO₂ were significantly increased, such as tensile strength, tensile modulus and elongation at break, and the damping capacity of PVA/SiO₂ film increased with increasing ratio of SiO₂.     

Fabrication of high conductivity dual multi-porous poly (l-lactic acid)/polypyrrole composite micro/nanofiber film

Dual multi-porous PLLA (poly(l-lactic acid))/H₂SO₄-doped PPy (polypyrrole) composite micro/nano fiber films were fabricated by combining electrospinning with in situ polymerization. The morphologies and structures of the resulting samples were analyzed by scanning electron microscopy (SEM). It was found that the composite micro/nano fibers exhibited a core-shell structure and the composite fiber film had a dual multi-pore structure composed of pores both in the fibers and among the fibers. Semiconductor parameter analyzer was used to characterize the electrical properties of the samples. It was interesting to find that all the PLLA/H₂SO₄-doped PPy composite micro/nano fiber films had higher conductivity than H₂SO₄-doped PPy particles when the polymerization time up to 180 min. Effects of the pyrrole synthesis conditions on the pore size and the conductivity of PLLA/PPy composite fiber film were assessed. By optimizing the polymerization conditions, the max conductivity of this composite fiber film was about 179.0 S cm⁻¹ with a pore size of about 250 μm. The possible mechanism of PLLA/H₂SO₄-doped PPy composite micro/nano fiber films had much higher conductivity than H₂SO₄-doped PPy particles was discussed.     

Synthesis and properties of a novel isomeric polyimide/SiO2 hybrid material

A novel isomeric polyimide/SiO₂ hybrid material was successfully prepared through sol–gel technique, and its structure, thermal properties and nano-indenter properties were investigated. First, 3-[(4-phenylethynyl)phthalimide]propyl triethoxysilane (PEIPTES) was successfully synthesized, its structure was characterized by elemental analysis, FT-IR and ¹³C NMR. The researches on solubility and thermal properties of PEIPTES show that it can be used for modifying nano-SiO₂ precursor. Nano-SiO₂ precursor was synthesized by tetraethoxysilane (TEOS) through sol–gel technique. Then the PEIPTES solution and the nano-SiO₂ precursor were mixed for 6 h to let the PEIPTES molecules react with the nano-SiO₂ precursor, and modified nano-SiO₂ precursor was obtained. The modified reaction was confirmed by the analyses of FT-IR. At last, isomeric polyimide/SiO₂ hybrid material was produced by using isomeric polyimide resin solution and the modified nano-SiO₂ precursor after heat treatment process. The structure analysis by SEM indicated that SiO₂ particles dispersed in isomeric polyimide matrix homogeneously with nanoscale. Thermogravimetric analyzer, dynamic mechanical thermal analyzer and nano-indenter XP was employed to detect the properties of the materials, the results demonstrated that isomeric polyimide/SiO₂ hybrid material has much better thermal properties and nano-indenter properties than those of isomeric polyimide. It is confirmed that PEIPTES acts as a bridge between the SiO₂ particles and the isomeric polyimide matrix in the hybrid material, because the ethoxyl of PEIPTES could participate in the hydrolyzation and condensation to form chemical bond with SiO₂ particles and its phenylethynyl group could take part in the cross-curing reaction of isomeric polyimide.     

Adjusting the properties of silicone rubber filled with nanosilica by changing the surface organic groups of nanosilica

A series of nanosilica (denoted as nano-SiO₂) surface-capped with organic modifiers hexamethyldisilazane (denoted as HMDS; molecular formula: C₆H₁₉NSi₂) and KH570 (molecular formula: C₁₀H₂₀O₅Si) containing CC double bond were prepared by in situ surface-modification method. As-obtained nano-SiO₂ particles were characterized by Fourier transform infrared spectrometry and transmission electron microscopy, and they were also used to reinforce silicone rubber (denoted as SR) in order to improve the mechanical properties. Moreover, a universal material testing machine was performed to determine the mechanical properties of the SR-matrix nanocomposites. Results showed that the surface properties of nano-SiO₂ can be adjusted by changing the ratio of these modifiers. The tensile strength, tear strength and elongation at break of nano-SiO₂/SR nanocomposites are comparable to or even better than those of R-106/SR nanocomposite (R-106 refers to commercially obtained fumed SiO₂ nanoparticles that was modified with silane coupling agent). The mechanical strength of nano-SiO₂/SR nanocomposites especially for tear strength largely improve with adding a small amount of CC content of the surface-capped nano-SiO₂. More importantly, it could be feasible to manipulate the mechanical properties of silicone rubber by properly adjusting the dosages of surface-modifiers HMDS and KH570 during the preparation of in situ surface-capped nanosilica, which could be of special significance to developing high performance SR-matrix nanocomposites.     

Effect of nano-SiO2 modified emulsion sizing on the interfacial adhesion of carbon fibers reinforced composites

The influence of nano-SiO₂ modified epoxy emulsion sizing on the interfacial adhesion properties of carbon fibers reinforced composites was investigated. The interfacial interaction between carbon fibers and the matrix was characterized by X-ray photoelectron spectrometry (XPS), scanning electron microscopy (SEM) and three-point short-beam shear testing. The results showed that the amount of hydroxyl groups was slightly increased on the carbon fibers surface after treatment with nano-SiO₂ modified sizing. Compared to the unsized composites, the interlaminar shear strength (ILSS) values for the composites with unmodified sizing and nano-SiO₂ modified sizing were increased by 9% and 14%, respectively. The holes and carbon fibers pullout were not observed in their fracture sections. Surprisingly, the fracture section of the composites with nano-SiO₂ modified sizing was more compact and the fiber debonding was more difficult.     

The running-in tribological behavior of nano-SiO2/Ni composite coatings

The running-in tribological behavior of the electrodeposited nano-SiO₂/Ni composite coatings is investigated using an M-200 block-on-wheel friction and wear tester. The results show that the electrodeposited nano-SiO₂/Ni composite coatings exhibit good wear resistance in the running-in period. With increasing nano-SiO₂ particle content in the electrodeposition plating solution, the wear resistance of the composite coatings are first improved and then decreased slightly, and the friction coefficient decreases first and then increased. If the nano-SiO₂ particle content in electrodeposition plating solution is 10 g/L, the composite coatings show the best wear resistance.     

无皂乳液聚合制备纳米SiO_2/丙烯酸酯复合乳液

在丙烯酸酯乳液无皂聚合过程中引入正硅酸乙酯,利用原位水解形成的纳米SiO2粒子制备了具有互穿网络结构的纳米SiO2/聚丙烯酸酯复合乳液。采用傅立叶红外光谱、透射电镜、粒度分析仪、热分析仪以及拉力实验机等表征了复合乳液的结构、形态、粒径、耐热性以及力学等性能。研究了反应型乳化剂对复合乳液的耐水性和粒径及其分布的影响,以及不同的正硅酸乙酯用量对复合乳液热学性能和力学性能的影响。结果表明,复合乳液的耐水性优异,粒径小、单分散性好。SiO2无机网络在丙烯酸酯聚合网络中起到了交联点的作用,并与有机相之间有良好的键合;复合乳液的热稳定性和摆杆硬度随着正硅酸乙酯(TEOS)用量的增加而增强,而拉伸强度、断裂延伸率则先增大后减小。     

Effect of nano-SiO2 on the performance of poly(MMA/BA/MAA)/EP

In the present work, the dispersive stability of nano-SiO₂ with coupling agent A-174 has been investigated, then in situ nano-SiO₂-MMA/BA/MAA copolymerization has been polymerized. Furthermore, the effects of nano-SiO₂ on performance of poly(MMA/BA/MAA)/EP have been studied, too. The results show that the nano-SiO₂ is soft agglomerate, which diameter is about 2.08 μm. But when it was oscillated by ultrasonic wave with adapt separating agent in low molecule solution, nanometer grade nano-SiO₂ particle could be attained, the average particle diameter is about 45 nm. In addition, the dispersive stability of nano-SiO₂ as treated by A-174 in polymerization system increase. As 3% of nano-SiO₂ treated by 4% of A-174 is added, the shear strength of the thermosetting acrylic-epoxy resin increase about 68%, up to 20.07 MPa, and its heat decomposition temperature increase from 332 °C to 386 °C, furthermore, the excellent water resistance and transparency have been obtained.