纳米TiO2/聚乳酸复合材料的制备和表征

采用原位聚合的方法制备了有机化处理过的纳米 TiO 2粒子质量分数分别为 1 wt %、3 wt %、5 wt %和10 wt %的 4种纳米 TiO 2/聚乳酸复合材料。SEM结果表明 , 当纳米 TiO 2粒子质量分数较低时 , 纳米 TiO 2在聚乳酸基体中呈现均匀稳定分散 , 而质量分数较高时则发生团聚。通过力学和热学等性能测试发现复合材料的最大热分解温度、 玻璃化转变温度和力学性能相对于聚乳酸有较大幅度提高 , 其中纳米 TiO 2的质量分数为 3 wt %时改善效果最明显 , 其最大热分解温度、 玻璃化转变温度分别比聚乳酸提高了 25. 3℃和 4. 9℃, 拉伸强度、 断裂伸长率和弹性模量分别提高了 83. 6 %、 6. 73 %和 129. 4 %。     

T700碳纤维增强环氧树脂基复合材料自然老化性能与机制

为验证复合材料的耐久性,对T700碳纤维增强环氧树脂基复合材料经自然老化后的微观形貌、表面元素含量、热性能与力学性能等进行了研究。结果表明: 在光氧老化与热氧老化的共同作用下,T700碳纤维增强EP-A环氧树脂基（T700/EP-A）复合材料表层树脂将发生老化降解,并且随自然老化时间的延长,T700/EP-A复合材料的玻璃化转变温度逐渐降低,未老化试样的玻璃化转变温度为207℃,经过自然老化处理3年后,其玻璃化转变温度降低为180℃,延长自然老化时间至5年时,其玻璃化转变温度进一步降低至172℃。而自然老化过程对复合材料力学性能可能同时存在着增强效应与损伤效应,因此造成了T700/EP-A与T700/EP-B复合材料的不同力学性能表现出相异的变化趋势。随自然老化时间延长,T700/EP-A与T700/EP-B复合材料纵向拉伸强度表现出先升高后降低的趋势,纵向弯曲强度表现出逐渐升高的趋势,纵向压缩强度与层间剪切强度存在波动,未呈现出明显变化。      

超声波辅助制备癸酸-棕榈酸@改性SiO2调温调湿复合材料超声波辅助制备癸酸-棕榈酸@改性SiO2调温调湿复合材料

以硅烷偶联剂改性SiO₂为壁材,癸酸（DA）-棕榈酸（PA）为芯材,利用超声波辅助溶胶-凝胶法制备DA-PA@改性SiO₂调温调湿复合材料,分析了硅烷偶联剂用量、超声波功率、超声波时间和超声波温度对DA-PA@改性SiO₂调温调湿复合材料粒径的影响,以及相关性能。结果表明,利用超声波辅助溶胶-凝胶法制备DA-PA@改性SiO₂调温调湿复合材料,可以显著降低粒径尺寸和减小粒径分布。当硅烷偶联剂用量为4.0 g、超声波功率为120 W、超声波时间为100 min和超声波温度为60℃时,DA-PA@改性SiO₂调温调湿复合材料的粒径较小且粒径分布较窄,即d₉₀=87.36 nm、d₅₀=63.34 nm、d₁₀=44.02 nm和d₉₀-d₁₀=43.34 nm,在相对湿度40.0%~65.0%范围内的平衡含湿量为0.1864~0.2379 g/g,相变温度为20.23~23.59℃,相变潜热为40.91~46.72 J/g,稳定性能良好。      

Fe-Si磁性颗粒/环氧树脂复合材料的冲击和磁学性能

采用双酚A型WSR-615和缩水甘油胺型AG-80环氧树脂为基体,以Fe-Si磁性颗粒为填料,通过热压成型方法制备了高含量磁性Fe-Si颗粒/环氧树脂复合材料。研究了环氧树脂基体的玻璃化温度和冲击强度及Fe-Si磁性颗粒含量对Fe-Si/环氧树脂复合材料的冲击强度和磁化强度的影响及温度敏感性。研究结果表明：随着磁性颗粒含量的增加,Fe-Si/环氧树脂复合材料的冲击强度和磁性能增加。当磁性颗粒体积分数由54 vol%增加到66 vol% 时,Fe-Si/环氧树脂的冲击强度和饱和磁化强度分别由4.03 kJ/m²和162.07 emu/g增加到7.16 kJ/m²和175.04 emu/g。Fe-Si/环氧复合材料在-60 ℃~140 ℃ 范围内的温度敏感性低,符合实际应用对复合材料稳定性的要求。     

十六醇-十六酸-十二酸/SiO_2三元相变体系复合材料的热湿性能

以十六醇(H)-十六酸(PA)-十二酸(LA)为相变材料,SiO_2为载体材料,采用溶胶-凝胶法制备不同HPA-LA用量的H-PA-LA/SiO_2三元相变体系复合材料。采用等温吸放湿法和步冷曲线法对H-PA-LA/SiO_2三元相变体系复合材料的湿性能和热性能进行测试,同时利用FTIR、XRD、SEM、LPSA和DSC对H-PA-LA/SiO_2三元相变体系复合材料的组成结构、晶体结构、微观形貌、粒径分布、相变温度和相变焓进行表征。结果表明:当HPA-LA用量为0.06mol时,所制备的H-PA-LA/SiO_2三元相变体系复合材料在人体舒适度范围内具有良好的热湿综合性能,即相对湿度为40%~65%时,平衡含湿量为0.07~0.10g/g,相变温度为26.29℃,相变焓为70.55J/g。     

混合溶剂分散法制备耐高温、高导热六方氮化硼/半芳香聚酰胺12T复合材料及其性能

制备兼具优异耐高温性能和导热性能的聚合物基复合材料对于电子元器件的封装保护、高效散热和稳定成型至关重要。本文通过混合溶剂分散法(MSD)制备了六方氮化硼(BN)/半芳香聚酰胺12T (PA12T)复合材料,并对复合材料的微观结构、导热、耐高温、介电和力学性能进行了表征。结果表明:混合溶剂分散法可以有效实现BN和PA12T粉末的均匀悬浮,并可协同真空辅助自组装法与真空热压法构筑具有均一分散和取向结构的复合材料。研究表明,当BN/PA12T复合材料中的BN含量为40wt%时,混合溶剂分散法制备的样品的平面导热率可以达到2.73 W/(m·K),是机械混合法(MM)制备的样品(1.59 W/(m·K))的1.72倍,同时其具有优异的力学性能、低介电常数(3.6)、介电损耗(0.016)和显著的耐高温性能(维卡软化点超过250℃且初始分解温度可达446℃)。综上所述,混合溶剂分散法制备的BN/PA12T复合材料在电子封装及热管理领域中具有广阔的应用前景。      

Elevated temperature mechanical properties of continuous metallic glass ribbon-reinforced glass-ceramic matrix composites

Effect of temperature on the modulus of rupture of glass-ceramic matrix composites reinforced with very small volume fractions (1%) of continuous metallic glass ribbons was studied. The failure modes in such composites were found to significantly depend on the test temperature. Variations in the strength of the matrix, and the interfacial shear strength between the matrix and the ribbons due to changes in the test temperature, were found to control the elevated temperature strength and failure mode of these composites.     

纳米金刚石/酵母-壳聚糖复合微球的制备及光热控释性能

开发高性能功能性光热凝胶并建立药物控释模型对农药智能输送材料的开发具有重要意义。以酵母-壳聚糖水凝胶(YS-CS)为基体,引入光热材料纳米金刚石(DND),通过碱凝胶法合成了纳米金刚石/酵母-壳聚糖(DND/YS-CS)交联网络结构复合凝胶微球,研究了复合微球的微观结构、力学性能和光热转换性能;以吲哚丁酸(IBA)为模型药物,探讨DND/YS-CS对IBA的负载性能和控释性能,揭示复合微球对IBA的光热控释机制。结果表明：复合微球具有良好的力学性能,在分别超声和离心1 h后,DND含量为2.0 mg/mL复合微球保水能力分别达到70.5%和74%;复合微球具有良好的光热转换能力,一个太阳光强度下,最高温度可达37.6℃;DND含量为1.2 mg/mL复合微球对IBA的吸附量最高,可达到41.73μg/mg;微球在光下药物释放模式符合Korsmeyer-Peppas模型,在光下具有明显的刺激响应行为,药物释放呈现“开-关”模式。通过控制光的照射强度控制药物释放,在农业领域有广阔的应用前景。     

Influence of fiber content on the mechanical and dynamic mechanical properties of glass/ramie polymer composites

The combination of glass and ramie fibers with a polyester matrix can produce a hybrid material that is competitive to all glass composites (e.g. those used in the automobile industry). In this work, glass and ramie fibers cut to 45 mm in length were used to produce hybrid polymer composites by resin transfer molding (RTM), aiming to evaluate their physical, mechanical and dynamic mechanical properties as a function of the relative glass–ramie volume fractions and the overall fiber content (10, 21 and 31 vol.%). Higher fiber content and higher ramie fiber fraction in the hybrid composites yielded lower weight composites, but higher water absorption in the composite. The mechanical properties (impact and interlaminar shear strength) of the composites were improved by using higher fiber content, and the composite with 31 vol.% of reinforcement yielded the lowest value for the reinforcement effectiveness coefficient C, as expected. Although the mechanical properties were improved for higher fiber content, the glass transition temperature did not vary significantly. Additionally, as found by analyzing the adhesion factor A, improved adhesion tended to occur for the composites with lower fiber content (10%) and higher ramie fiber fraction (0:100) and the results for the adhesion factor A did not correspond to those found by the analysis of the tan delta peak height.     

FPP对Al(OH)3/PP复合材料的流动性、阻燃性和结晶行为的影响

用熔融挤出法制备了不同接枝率的官能团化聚丙烯（FPP），研究了FPP对Al(OH)3/PP复合材料的流动性、阻燃性和结晶与熔融行为等物性的影响。FPP加入使Al(OH)3/PP的熔融指数增加，流动性与填料分散性改善，氧指数提高和结晶与熔融行为改变。探讨FPP在Al(OH)3/PP复全材料中的作用机理。     

T800碳纤维/9518氰酸酯复合材料的性能

通过差示扫描量热（DSC）法研究了9518氰酸酯的固化反应,制定了9518氰酸酯的固化工艺;通过动态热机械分析（DMA）测试、力学性能测试、金相显微镜和SEM等方法研究了T800碳纤维/9518氰酸酯复合材料的受热行为、力学性能、纤维微观形貌和界面特性。结果表明：9518氰酸酯的固化反应只有一个固化反应放热峰,其比较合理的固化工艺为130℃/0.5 h+160℃/0.5 h（加压合模）+200℃/2 h+230℃/2 h。T800碳纤维/9518氰酸酯复合材料的玻璃化转变温度为255℃,其各项力学性能比T700碳纤维/9518氰酸酯复合材料提高均大于10%,室温-湿态力学性能保持率大于83%,200℃的力学性能保持率大于60%。T800碳纤维不规则的截面和表面沿长度方向的沟槽有利于树脂与纤维间形成良好的结合界面。     

The effect of formulated molecular weight on temperature resistance and mechanical properties in polyimide based composites

This experimental study examines the role of formulated molecular weight between crosslink sites on the temperature resistance and mechanical properties of composites based on a polyimide containing a diphenyl thioether unit (PTI). The composites are fabricated by in situ polymerization of monomer reactants (PMR) using three monomeric ingredients: bis(3,4-dicarboxyphenyl) sulfide dianhydride (TDPA); 4,4-methylene dianiline (MDA); and the monomethyl ester of norbornene anhydride (NE). By changing monomeric molar ratio, three formulations are prepared, in which formulated molecular weight between crosslink sites varies from 1487 to 3446 g mol^–1. Unidirectional composite laminates from each formulation and T300 carbon fibres are compression moulded and cut into a series of test specimens. By measuring the glass transition temperature (T _g), Mode I interlaminar fracture toughness (G _IC) and other mechanical properties at room and elevated temperatures, the influences of formulated molecular weight on the temperature resistance and mechanical properties of PTI-based composites are investigated.     

Question of the convergence of iteration methods of solving the inverse heat-conduction problem

The convergence of iteration methods of solving the inverse heat-conduction problem depending on the type of desired boundary function is numerically investigated.Notation t time - t_p length of the time interval - x space coordinate - b thickness - T(x, t) temperature - C(T) bulk specific heat of the material - (T) heat conduction coefficient of the material - (x) initial temperature distribution - q thermal flux density - f(t) measured temperature - (x, t) adjoint variable - , , p parameters of the method of conjugate gradients - k number of the iteration Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 45, No. 5, pp. 770–773, November, 1983.     

制备均匀粒度分布的棕榈醇-棕榈酸-月桂酸@(Ce-La-TiO2)光-热-湿复合材料

以Ce-La-TiO₂空心微球作为载体材料,棕榈醇（H）-棕榈酸（PA）-月桂酸（LA）作为相变材料,采用溶胶-凝胶法和真空吸附法制备H-PA-LA@（Ce-La-TiO₂）光-热-湿复合材料。通过均匀设计与径向基函数（RBF）神经网络结合,考察制备因素（如磁力搅拌转速、恒温回流温度、煅烧升温速度和真空恒温干燥箱真空度）对H-PA-LA@（Ce-La-TiO₂）光-热-湿复合材料粒度分布的影响,并且对粒度分布最均匀的H-PA-LA@（Ce-La-TiO₂）光-热-湿复合材料进行表征与测试。结果表明,当扩展系数为0.45~0.55时,RBF神经网络具有最佳的逼近效果。粒度分布最均匀H-PA-LA@（Ce-La-TiO₂）光-热-湿复合材料的制备工艺参数为：磁力搅拌转速为1 762 r/min、恒温回流温度为66.9℃、煅烧升温速度为2.43℃/min和真空恒温干燥箱真空度为0.58 MPa。基于上述制备参数,中位径d₅₀为190.02 nm,粒径分布区间的实测值为180.50 nm,实测值与预测值吻合较好,相对误差为3.58%。在相对湿度35%~85%的平衡含湿量为0.0369~0.1702 g/g,相变温度为24.21~29.48℃,相变焓为31.24~33.07 J/g,经过5 h对甲醛的降解效率为56.92%。     

基于生物质吸附效应的石膏基多功能化复合材料制备与性能

采用废弃核桃壳制备生物质多孔活性炭（PC）,利用真空吸附法将癸酸（CA）封装于PC的孔结构中,形成癸酸-多孔活性炭（CA-PC）。然后将CA-PC与硅藻土（Di）、石膏（Gy）进行复合制备CA-PC/Di-Gy多功能化复合材料,并对其热性能、湿性能以及吸附性能进行测试。采用BET、FTIR、SEM以及DSC等技术对CA-PC/Di-Gy多功能化复合材料进行表征,并分析其结构。结果表明:以废弃核桃壳制备的PC具有发达的孔隙结构,不仅能够包裹CA,而且可以吸附甲醛。CA-PC/Di-Gy多功能化复合材料具有良好的调温调湿性能与吸附率,即在32℃附近出现温度平台,在相对湿度40%~60%的平衡含湿量为0.0859~0.2310 g/g,经过4 h对甲醛气体的吸附率接近40%。     

Moisture effects on the toughness, mode-I and mode-II of particles filled quasi-isotropic glass–fibre reinforced polyester resin composites

An experimental programme is presented for the effect of moisture on the toughness, mode-I and mode-II of aluminium tri-hydrate and polyethylene filled and unfilled quasi-isotropic glass–fibre reinforced epoxy–vinylester resin (GFRP) composites. Specimens were exposed in water at room temperature (20°C) for a period of 8 months and the effect of moisture content on toughness, GIc and GIIc values were obtained at an interval of every 2 months. Some samples were exposed in hot water at 40°C temperature to accelerate the uptake of moisture and produce saturated composites. The results indicate that equilibrium moisture content and diffusion coefficients increase with increase of weight of filler content in GFRP composites which is linked to an increase in microscopic cracking. Also mode-I, toughness of all composites increased with an increase in moisture uptake, mode-II toughness was relatively unaffected. Aluminium-tri-hydrate filled GFRP composites showed a higher moisture uptake, which resulted in higher values of both mode-I and mode-II, toughness than the polyethylene filled and unfilled GFRP composites. © 1998 Chapman & Hall     

端炔基遥爪型聚酰亚胺(API)的制备及T300碳纤维布/API复合材料性能

以3,4'-氧双邻苯二甲酸酐、1,3-双（氨丙烷基）四甲基二硅醚和间氨基苯乙炔或对氨基苯基炔丙基醚为原料,合成了六种端炔基遥爪型聚酰亚胺（API）,采用模压成型制备了T300碳纤维布增强API（T300碳布/API）复合材料。利用FTIR、1H NMR、DSC、TGA、DMA等方法研究了API树脂及T300碳布/API复合材料的结构和性能。结果表明,六种API树脂溶解性良好,其加工窗口随分子量的增加而变宽,端炔丙氧基API（API-e）树脂的加工性能优于端乙炔基API（API-a）树脂;API树脂固化物的热稳定性随分子量的增加而降低,API-a树脂固化物5%热失重温度（T_d5）和800℃残留率高于API-e固化物,分别为473.7℃和48.8%;T300碳布/API复合材料的玻璃化转变温度可达220℃以上,其力学性能随其分子量的增加而提高,T300碳布/API-e复合材料在室温和200℃的力学性能均优于T300碳布/API-a复合材料。室温下T300碳布/API-e复合材料的弯曲强度为636.5 MPa,拉伸强度为406.1 MPa,层间剪切强度（ILSS）为48.4 MPa,在200℃的弯曲强度和ILSS分别为381.9 MPa和33.9 MPa。      

ZA22/Al2O3短纤维复合材料高温拉伸行为的理论分析

采用日本产A G-10TA 型电子万能试验机对挤压铸造ZA 22/Al₂O₃短纤维复合材料的高温抗拉强度进行了测定, 并用Friend 修正的混合律模型对该试验结果进行了理论分析, 结果表明ZA 22/Al₂O₃短纤维复合材料及其基体的强度均随温度升高而下降, 但ZA 22合金基体的强度下降幅度更大。任一纤维体积分数的复合材料, 均存在一临界转变温度T crit; 超过该温度, 复合材料强度大于基体强度。纤维体积分数越大, 所需临界转变温度越低。在本试验中, V f 为15% 和20% 的复合材料的Tcrit分别为123℃和87℃。任一温度下, 复合材料均存在一临界纤维体积分数, 超过该纤维体积分数, 复合材料强度高于基体强度。温度越高, 临界纤维体积分数越低。对ZA 22/Al₂O₃短纤维复合材料来说, Friend 模型中的经验参数C3 的取值随温度升高而降低。      

纳米CaCO3改性聚四氟乙烯复合材料的性能

采用冷压烧结工艺制备聚四氟乙烯（PTFE）/纳米CaCO3复合材料,并研究了其性能。实验结果表明,通过差示扫描量热（DSC）分析,少量纳米CaCO3对PTFE结晶度有一定程度提高,起到异向成核作用;复合材料的结晶速率随结晶温度的升高而降低;相同的结晶温度下,复合材料的半结晶时间t1/2和最大结晶时间tmax高于纯PTF...     

Effect of carbide particles on the ablation properties of tungsten composites

The high temperature ablation behavior of tungsten composites containing carbides produced by vacuum hot pressing is studied as a function of reinforcement chemistry (ZrC and TiC) and content using a self-made oxyacetylene ablation equipment. A dynamic responding multiwavelength pyrometer was employed to measure the temperature of the ablation surface, and a thermocouple was employed to measure the temperature of the back surface during the time that a specimen was being ablated. The mass and linear ablation rates are lower in composites containing ZrC, decreasing with increasing particle content in both composites system. The values of the mass and linear ablation rates were in the order from high to low: W>30TiC/W>40TiC/W>30ZrC/W>40ZrC/W (30TiC/W stands for 30 vol.% TiC particle content in the W matrix, the same below). The important temperature curves of the ablation surfaces of specimens were successfully detected online. Ablated surfaces and vertical sections of the specimens were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Thermochemical oxidation of tungsten, TiC, and ZrC was the main ablation mechanism of ZrC/W and TiC/W composites. These ablation behaviors are discussed based on the thermophysical and chemical properties of both the composite systems.