熔体法OC/IIR/EPDM纳米复合材料的结构与性能研究

采用机械共混法制备有机粘土(OC)/IIR/EPDM纳米复合材料,并对其结构和性能进行研究.试验结果表明:采用机械共混法制备的OC/IIR/EPDM复合材料为插层型纳米复合材料;IIR与EPDM具有良好的相容性;当OC用量为30份、IIR/EPDM并用比为50/50时,OC/IIR/EPDM纳米复合材料的气密性能和物理性能较好.     

熔体法制备有机黏土/橡胶纳米复合材料的结构及性能

将有机黏土(OC)分别加入到天然橡胶(NR)、丁苯橡胶(SBR)、丁基橡胶(IIR)和三元乙丙橡胶(EPDM)中,通过熔体法制备了纳米复合材料。探讨了橡胶黏度及其分子结构对OC在复合材料中分散状况的影响,研究了复合材料的力学性能。结果表明,在以NR为基体的复合材料中。OC片层分散均匀,且剥离程度较高;在SBR,IIR,EPDM中,OC以插层结构为主,且插层效果从大到小的顺序依次为SBR,IIR,EPDM。与相应的纯胶相比,OC／NR纳米复合材料的定伸应力提高,拉伸强度和扯断伸长率有所下降;OC／SBR,OC／IIR,OC／EPDM纳米复合材料的定伸应力变化不大,拉伸强度和扯断伸长率明显提高,且OC／SBR和OC／EPDM复合材料的撕裂强度提高。     

界面对PE–LLD/Al（OH）3复合材料性能影响

制备了丙烯酸(AA)接枝线型低密度聚乙烯(PE–LLD)(PE–g–AA)高分子偶联剂,并将其用于改性PE–LLD/Al(OH)3复合材料。研究了PE–g–AA对PE–LLD/Al(OH)3复合材料的微观结构、力学性能、流变行为、电气绝缘性能的影响,并探讨了复合材料力学性能、电气绝缘性能和界面微观结构之间的关系。研究结果表明,PE–g–AA偶联剂显著改善了Al(OH)3填料与PE–LLD基体之间的界面作用机制,不但提高了复合材料的拉伸和冲击强度,而且增加了复合材料的断裂伸长率。另外,PE–g–AA提高了Al(OH)3在聚合物基体的分散性并作为绝缘层减少了填料之间的相互接触,因而获得的复合材料的电气绝缘性能在低偶联剂的掺量下大幅提升,达到电气绝缘性能要求。     

PMMA/ATO纳米复合材料的结构与导电性能

采用溶液共混的方式制备了聚甲基丙烯酸甲酯/纳米掺锑二氧化锡(PMMA/ATO)复合材料,分析了复合材料的微观相态结构及导电性能,并对复合材料的物理机械性能及热性能进行了研究.结果表明:经过钛酸酯偶联剂处理的纳米ATO在PMMA基体中分散良好,在含量较低的情况下即可获导电性能良好的复合材料;当纳米ATO的质量分数为5%时,复合材料具有良好的物理机械性能;纳米ATO在PMMA基体中起到了交联点的作用,使其玻璃化转变温度随着ATO的增加而升高,从而改善了PMMA的耐热性能.     

高性能橡胶/黏土纳米复合材料的制备与结构

研究了硬脂酸(SA)处理有机黏土(OC)制备橡胶/黏土纳米复合材料的结构与性能,并与未处理的OC制备的纳米复合材料进行了对比。结果表明,SA上的—COOH与OC片层表面的—OH发生了酯化反应,促使SA插层进入OC层间,使层间距扩大。采用SA处理OC制备出分散相态细致均匀、力学性能优异的丁腈橡胶/黏土(NBR/SA-OC)纳米复合材料;当OC与SA的质量比为10∶6时,纳米复合材料的性能最优。用带有极性和反应官能团的橡胶制备橡胶/黏土纳米复合材料,OC的分散性更好,与未处理的OC制备的纳米复合材料相比力学性能更优。     

环氧树脂/纳米Si_3N_4复合材料的制备与性能研究

以纳米 Si_3N_4为填料制备了环氧树脂/纳米 Si_3N_4复合材料。通过透射电镜观察到,纳米粒子在有机基体中分散均匀。研究了纳米 Si_3N_4对复合材料性能的影响,结果表明,添加纳米 Si_3N_4使复合材料的力学性能增加,当改性环氧树脂/纳米 Si_3N_4为100/3(质量比,下同)时,复合材料的拉伸强度、弯曲强度、冲击强度提高幅度最大,分别提高了145%、241%、255%。此时,复合材料的击穿场强提高的幅度也达到最大,在直流电压和交流电压下,分别提高了249%、146%;但添加纳米 Si_3N_4使复合材料的介电常数和介质损耗值减小;热重分析表明,环氧树脂/纳米Si_3N_4复合材料耐热性能有明显提高。并用"核-壳过渡层"结构模型初步探讨了各项性能改善的原因。     

玻纤增强聚丙烯木塑复合材料的性能研究

分别以聚丙烯(PP)、聚乙烯(PE)、玻纤增强PP/PE为基体材料,通过挤出成型制备了木塑复合材料(WPC)。研究表明,玻纤能够有效地提高WPC的性能,以玻纤增强PP/PE为基体制备的WPC的冲击强度、拉伸强度、弯曲强度、弯曲弹性模量分别达到4.58 kJ/m2,19 MPa,30.8 MPa,3520 MPa,性能优于以PP或PE为基体制备的WPC。     

石墨烯/聚乙烯高性能复合材料的制备与性能表征

采用液相超声分散热压制备了氧化石墨烯/聚乙烯(GO/PE)复合材料,研究了GO的微观结构,及GO/PE复合材料的热稳定性、力学性能、显微硬度及耐摩擦性能。对比纯PE与GO/PE复合材料可以发现,添加GO,复合材料的热稳定性、力学性能、显微硬度和耐磨性能有了明显提高,显微硬度的增加减少了PE及其复合材料与金属表面的有效接触面积,提高了材料的摩擦性能。     

聚乙烯/粘土纳米复合材料燃烧性能研究

使用锥形量热计、热重分析仪对聚乙烯(PE)／粘土纳米复合材料的燃烧性能进行了研究。结果表明，有机改性纳米粘土对PE燃烧性能有较大影响，随眷纳米粘土合量的增加，PE的热分解速率和最大热释放速率都明显下降，这对材料应用中的火灾安全性具有重要意义。     

中空玻璃微珠/纳米TiO_2/PE复合材料的隔热性能与结构的关系

采用中空玻璃微珠(GB)、纳米TiO2单独或复合填充聚乙烯(PE),研究了GB、纳米TiO2含量对复合材料光反射性能和隔热性能的影响。结果表明:GB、纳米TiO2的加入明显提高了PE的反射性能和隔热性能;当GB/PE、TiO2/PE复合材料的比例分别为2/7、1/7时,两种复合材料综合隔热性能达到最佳值,与纯PE相比,辐照5 min后阻隔密室的升温幅度分别下降了16.8℃和16℃,GB与纳米TiO2具有协同隔热作用,GB/PE、TiO2/PE、TiO2/GB/PE 3种复合材料中,GB/TiO2/PE(2/1/7)体系的隔热性能最好,辐照5 min后阻隔密室的升温幅度只有6.8℃比,纯PE下降了22.4℃。     

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.     

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.     

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。     

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.     

阻隔性PET/PEN共聚酯的性能研究

对共聚型阻隔聚酯PETNx(x为共聚酯中NDA占羧酸总质量的百分比)的热性能、流变性能和阻隔性能进行了研究。结果表明,PETNx体系属于假塑性流体。PETNx的CO2气体阻隔性优于常规PET;随着PETNx中NDA含量的增加,共聚物的玻璃化温度呈线性增高。