石墨/二硫化钼/丁腈橡胶复合材料的性能

采用机械共混法制备了石墨/二硫化钼(MoS2)/丁腈橡胶(NBR)复合材料,考察了石墨和MoS2用量对复合材料物理机械性能及摩擦性能的影响,并用扫描电子显微镜表征了填料在橡胶基体中的分散情况。结果表明,石墨/MoS2/NBR复合材料的拉伸强度、撕裂强度和邵尔A硬度均高于石墨/NBR复合材料和MoS2/NBR复合材料,当添加10份石墨和7份MoS2时,复合材料的物理机械性能最佳,且填料在橡胶基体中的分散性最好,摩擦因数达到最小值0.7。     

芳纶纤维增强丁腈橡胶的摩擦性能

研究了芳纶纤维增强丁腈橡胶(NBR)复合材料的物理机械性能和摩擦性能,并用扫描电子显微镜分析了芳纶纤维增强NBR复合材料的磨损表面和磨屑形貌。结果表明,芳纶的加入提高了NBR的拉伸强度;随着芳纶用量的增大,复合材料的扯断伸长率降低;芳纶的加入降低了NBR的摩擦系数和磨损率;当芳纶用量为20份时,复合材料的综合性能最佳。加入芳纶对NBR摩擦磨损形式的改变是NBR摩擦性能提高的重要原因。     

改性白炭黑补强NR/TPI的性能研究

本文选用双-(γ-三乙氧基硅基丙基)四硫化物(Si-69)为改性剂,利用球磨法制备了接枝改性白炭黑。利用热失重法(TG)分析了改性剂用量和改性时间等因素对接枝率的影响。将改性白炭黑用于天然橡胶(NR)/ 反式聚异戊二烯(TPI)的补强中,比较了未改性白炭黑和改性白炭黑对胶料的硫化性能、物理机械性能和动态性能等的影响。结果表明,在0~12份范围内,改性剂用量越大,白炭黑接枝率越高,但综合物理机械性能最佳值则出现在改性剂用量为10份时。在15~45 min范围内,改性时间对白炭黑接枝率影响不明显,但当改性时间为45 min时,综合物理机械性能最佳。白炭黑经接枝改性后改善了其在橡胶基体中的分散性和与橡胶基体的相容性,添加改性白炭黑胶料的抗湿滑性能、滚动阻力和动态生热性能均有改善。     

纳米淀粉/乙烯-乙酸乙烯酯橡胶复合材料的制备及性能研究

通过一步法制备纳米淀粉/乙烯-乙酸乙烯酯橡胶(EVM)复合材料,研究偶联剂KH570对复合材料性能的影响。结果表明:在不添加偶联剂KH570时,复合材料的物理性能明显提高,但纳米淀粉与EVM基体的相容性较差;偶联剂KH570的加入可以改善纳米淀粉与EVM基体的相容性;随着偶联剂KH570用量的增大,复合材料的硬度、300%定伸应力和拉伸强度逐渐增大;在本试验范围内,偶联剂KH570用量为2份时,复合材料的物理性能最佳。     

石墨/铜粉改善双马来酰亚胺复合材料摩擦性能

采用层压成型制备了2类改性双马来酰亚胺纤维复合材料,分别考察了石墨、铜粉的用量对纤维复合材料摩擦性能(摩擦系数,磨损率)和力学性能的影响,并用扫描电镜对复合材料的磨损表面形貌进行了分析。结果表明:石墨对改善双马来酰亚胺的摩擦磨损性能较铜粉更有效。石墨的质量分数为3%时,复合材料的摩擦磨损性能和力学性能达到最佳。     

氟醚橡胶摩擦磨损性能研究

研究了石墨、碳纤维和聚四氟乙烯不同用量和三者并用对氟醚橡胶摩擦磨损性能的影响,并用SEM对橡胶磨损表面形貌进行了分析。结果表明,石墨和聚四氟乙烯填充的氟醚橡胶以粘着磨损为主,磨损严重,而碳纤维填充的橡胶磨损主要是疲劳磨损,可显著提高氟醚橡胶的摩擦磨损性能。石墨和碳纤维并用可产生协同效应,两者用量均为15份时橡胶摩擦磨损性能较好,此时摩擦系数为0.378,磨损率为5.590×10-8mm3/Nm。     

NR/SBR并用橡胶基磁敏橡胶的制备及性能的研究

通过湿法预处理,用偶联剂KH-570对羰基铁粉进行表面改性,制备了综合性能较好的并用橡胶基实用型磁敏橡胶,研究了羰基铁粉含量对天然橡胶/丁苯橡胶(NR/SBR)并用橡胶基磁敏橡胶性能的影响;同时利用扫描电镜研究了改性羰基铁粉表面和磁敏橡胶复合材料断面的微观结构。结果表明,通过偶联剂改性的羰基铁粉其晶体结构未发生变化,且表面有一层致密的包覆层;以NR/SBR并用橡胶为基体的磁敏橡胶,当羰基铁粉用量为300份时,可表现出较好的机械性能和磁流变效应。     

纳米Si_3N_4/ACM复合材料的力学性能和硫化性能研究

采用大分子表面处理剂LMPB-g-KH570对纳米Si_3N_4表面进行修饰。利用共混技术制备了纳米Si_3N_4/ACM复合材料。利用RPA-8000、SEM、TEM等测试技术,对纳米复合材料的微观结构和性能进行了分析和评价。结果表明,大分子表面改性剂能有效改善复合材料的微观界面结构,促进纳米Si_3N_4在橡胶基体中的有效分散,橡胶硫化性能得到改善,力学性能得到提高。添加2.0份改性纳米Si_3N_4/ACM复合材料,胶料正硫化时间减少38 s,拉伸强度提高24.8%,撕裂强度提高3.39%。     

磷石膏晶须表面改性及其在PP中初步应用

采用硅烷偶联剂KH570对磷石膏晶须进行超声波表面改性。考察了改性时间、改性温度、改性剂用量等条件对磷石膏晶须的表面改性影响。并分析了KH570对磷石膏晶须改性作用机理。结果表明:当KH570的用量为磷石膏晶须质量的5%,改性时间为80 min,改性温度在50℃时,获得最佳的改性效果。由红外光谱分析可知磷石膏晶须表面羟基与KH570发生了化学键的作用。改性的磷石膏晶须/PP复合材料的相容性较好,复合材料力学性能较纯PP材料有所提高。     

硅烷偶联剂改性绢云母补强丁苯橡胶的研究

以片状绢云母粉体为基料,采用γ-巯丙基三乙氧基硅烷对绢云母表面改性,通过橡胶复合材料的力学性能评价表面改性效果。结果表明：改性剂用量2%、改性温度90℃、改性时间20 min为绢云母粉体最适宜的改性条件,此条件制备的绢云母/丁苯橡胶( SBR)复合材料力学性能改善明显。 FTIR分析表明：硅烷偶联剂与矿物表面发生了化学键合;SEM观察发现改性绢云母能均匀分散在橡胶基体中,与橡胶形成良好界面结合,证实了绢云母通过表面改性能有效的提高对丁苯橡胶的补强性能。     

Synthesis of dysprosium/Mn–Cu ferrite binary nanocomposite: Analysis of structural,morphological, dielectric,and optomagnetic properties

Manganese–copper ferrite (MCFO) and dysprosium (Dy)-doped manganese–copper ferrite nanocomposites (Mn_0.5Cu_0.5Dy_xFe_2−xO₄) (x = 0, 0.05, 0.10, and 0.15) were synthesized by sonochemical method. Crystal structure and the structural parameters of the MCFO were analyzed based on the doping concentration of Dy ion. It was observed that the average crystalline size of the synthesized nanocomposite decreases when the concentration of Dy increases. The existing spherical surface morphology of the MCFO and Dy-doped MCFO nanocomposites were obtained through scanning electron microscopy. In the UV spectrum, the pristine MCFO sample showed an absorbance peak at 743 nm whereas the absorbance values of Dy-doped ferrite nanocomposite considerably shifted (blue) toward a lower wavelength (231–222 nm). The dielectric parameters of all ferrite nanocomposites were studied in the frequency range of 100 Hz to 5 MHz. The dielectric spectrum revealed that dielectric constant and loss tangent decreased with increased doping concentration of Dy ion. The saturation magnetization also changed with Dy doping in MCFO. The impact of Dy on manganese–copper ferrite changed the optical, dielectric and magnetic properties of the prepared binary ferrite nanocomposite, which can be used for microwave-absorbing material applications.     

Mechanical Properties of Compression Molded Banana Pseudo-stem Filled Unplasticized Polyvinyl Chloride (UPVC) Composites

Mechanical strengths of a banana pseudo-stem (BPS) fiber and unplasticized polyvinyl chloride (UPVC) composite were evaluated to assess the possibility of using it as a new material in engineering applications. Samples were fabricated by the compression molding process with reference to the effect of filler loading. The samples were submitted to mechanical tests to measure tensile, flexural, and impact properties of the composites. The nature of adhesion between the matrix and the reinforcement and information relating the structure of mechanical properties can be obtained by scanning electron microscopy (SEM) assessment of the composite fracture surface. The mechanical properties show that the composites did not have good adhesion between filler and matrix; on the other hand, the filler insertion improved the flexural modulus and the material rigidity.     

单向玻璃纤维-铝合金层板的几种力学性能研究

本文用实验方法研究了单向玻璃纤维-铝合金层板的拉伸性能、疲劳性能和冲击性能。利用金属体积分数理论验证了这类层板的拉伸性能。通过对其疲劳性能的实验研究，发现裂纹扩展速率的大小及刚度的下降与加载的最大循环应力密切相关的规律。实验发现该层板具有比铝合金好得多的冲击性能。     

核壳型纳米粒子合成方法及其性能的研究进展

核壳纳米粒子作为复合纳米粒子一个重要的分支,由于其光、磁和催化等方面的优异性能,近年来引起了人们广泛的关注.本文主要介绍了核壳纳米粒子的制备方法及诸多性能,并对核壳纳米粒子的发展进行了展望.     

TMPTMA在硅橡胶中的应用研究

研究了助交联剂三羟甲基丙烷三甲基丙烯酸酯(TMPTMA)对硅橡胶硫化性能、力学性能、低温性能和粘接性能的影响。结果表明,加入少量TMPTMA能改善硅橡胶的硫化特性和工艺性,提高硫化胶的硬度,降低硅橡胶的结晶温度,并有效提高硅橡胶与金属的粘接强度;但TMPTMA用量超过一定数值后,由于TMPTMA部分自聚合,在硅橡胶内形成一定的交联网络,造成两相界面粘接力变差,致使硅橡胶的拉伸强度降低。当TMPTMA用量为1份时,硅橡胶具有最佳的综合性能。     

聚氨酯种类对机械性能以及阻尼性能影响研究

分别以聚四氢呋喃醚二醇(PTMEG)、聚氧化丙烯二醇(PPG-1000)为软段,以二苯基甲烷二异氰酸酯(MDI-50、MDI-100LL),以及扩链剂1,4-丁二醇(BDO)、三羟甲基丙烷(TMP)为硬段,采用预聚体法制备了聚氨酯弹性体。并系统研究了聚氨酯体系中各组分的种类对材料机械性能和阻尼性能的影响。     

A new precursor to lightweight porous Si–Al–O–B ceramics with enhanced microwave transmissivity

Nowadays, complicated preparation processes and harsh sintering conditions wave transparent ceramics limit its further development. To solve this problem, we explore a promising precursor by adopting a polymerization-pyrolysis method to prepare porous Si–Al–O–B ceramics at a mild sintering condition (1000 °C). The porous Si–Al–O–B ceramics exhibits enhanced wave transparency at 10–16 GHz with a low dielectric constant (<3), a low loss angle tangent value (<0.01), and simultaneously, a relative high flexible strength of 82 MPa. According to the results of the XRD and FTIR analysis, porous Al₄B₂O₉ crystallization dispersed in the amorphous SiO₂ matrix constructs the main phases of the products. The changes of Al and B elements are confirmed to have an effect on the phase compositions and micro structure of the composite ceramics, which obviously affect the mechanical and dielectric properties of the derived ceramics. The as-prepared porous Si–Al–O–B ceramics could be a potential candidate for next generation electronic window materials due to its low dielectric constant and loss angle tangent value, as well as high flexible strength.     

Effects of support and additive on oxidation state and activity of Pt catalyst in propane combustion

The effects of support and additive on the oxidation state and catalytic activity of Pt catalyst in the low temperature propane combustion were systematically investigated on Pt/MgO, Pt/Al₂O₃ and Pt/SiO₂–Al₂O₃. The catalytic activity varied much with both support materials and additives. The catalyst on the more acidic support showed higher activity, and the catalytic activity on every support materials increased as the electronegativity of additives increased, while some additives decreased the activity. The oxidation state of platinum, estimated by white line intensity of Pt L_III-edge XANES spectrum, also varied with the support and additives, and additives with higher electronegativity greatly prevented the platinum from its oxidation under oxidising atmosphere. Among almost all the catalysts with various supports and various additives, a clear relationship was observed between the oxidation state of platinum and the catalytic activity; the more metallic platinum showed higher activity. Thus, it was concluded that the total electrophilic/electrophobic property derived from those of the support and additive controls the oxidation state of platinum, which intensively affects the catalytic activity; i.e. higher electrophilic property provides less oxidised platinum, resulting in high catalytic activity. The mechanism of this effect was also discussed on the basis of thermochemical data, and it was proposed that the electrophobic materials promote the noble metal oxidation since the noble metal oxo-anion such as PtO^δ− is more stabilised with electrophobic cation.     

聚丙烯基抗菌塑料的制备与性能研究

利用熔融挤出共混技术制备了聚丙烯(PP)基抗菌塑料。研究了抗菌母料Antim-PP对PP的抗菌性能和力学性能的影响。结果表明,当抗菌母料与PP的质量比为4:100时,抗菌PP塑料对大肠杆菌的抗菌率大于99%,抗菌母料的加入使共混物的冲击性能有明显改善,其他力学性能基本不受影响。