单壁碳纳米管/丁基橡胶复合材料的性能研究

研究单壁碳纳米管（SWCNTs）/丁基橡胶（IIR）复合材料（包括混炼胶和硫化胶）的性能。结果表明：随着SWCNTs用量的增大,SWCNTs/IIR混炼胶的t10和t90缩短,Payne效应增强,损耗因子增大,硫化胶的交联密度增大,耐热性能提高;SWCNTs对IIR具有补强作用,填充2份SWCNTs时补强效果最好;当SWCNTs用量为4份时,SWCNTs/IIR硫化胶的电导率、相对介电常数和介电损耗因子出现逾渗,当SWCNTs用量达到6份及以上时,硫化胶的导电性能趋于稳定。     

硫化剂双25对三元乙丙橡胶/乙烯-辛烯共聚物共混胶动态性能及耐热老化性能的影响

采用橡胶加工分析仪(RPA)分析硫化剂双25对三元乙丙橡胶(EPDM)/乙烯-辛烯共聚物(POE)共混胶动态性能及耐热老化性能的影响。结果表明,硫化剂双25用量不同的混炼胶的动态性能之间差异较小,而硫化胶因交联密度不同,动态性能差异较大。EPDM/POE混炼胶和硫化胶的储能模量随频率升高而增大,随应变和温度升高而减小;混炼胶的损耗因子随频率升高而降低,随应变及温度升高而增大;硫化胶的损耗因子对频率的依赖性不明显,随应变升高而增大,随温度升高而降低。硫化剂双25用量不同的硫化胶经过RPA无氧高温老化后,损耗因子增大;当硫化剂双25用量为3.5份时,硫化胶的损耗因子在老化前后都较小,耐热老化性能最好。     

硫黄硫化体系对IIR/EPDM共混胶力学性能的影响

研究IIR/EPDM体系中共混比、硫黄硫化体系对其共混胶性能的影响。结果表明 ,IIR与EPDM共混相容性较好 ,可以达到共硫化 ;IIR/EPDM共混比为 75 /2 5时共混胶性能最好 ;用传统硫化体系 (CV)、有效硫化体系 (EV)和半有效硫化体系 (SEV)都能得到性能较好的共混胶 ,其中以CV体系的硫化胶性能最好。     

黑液-蒙脱土在丁基橡胶-三元乙丙橡胶并用体系中的应用研究

以黑液-蒙脱土(BL-MMT)为填充补强剂,制备了丁基橡胶(IIR)和三元乙丙橡胶(EPDM)的复合材料,考察了IIR与EPDM的比例、硫化体系和BL-MMT的量对BL-MMT/IIR/EPDM复合材料性能的影响。研究结果表明,IIR与EPDM比例减小可以改善BL-MMT/IIR/EPDM的加工性能,提高其耐热氧老化性能,IIR与EPDM比例为80/20时BL-MMT/IIR/EPDM复合材料的综合性能较好;普通(CV)硫化体系、半有效(SEV)硫化体系和有效(EV)硫化体系均可以使BL-MMT/IIR/EPDM复合材料共硫化,CV硫化体系得到的硫化胶综合物理性能最好,EV硫化体系得到的硫化胶耐热氧老化性能最好;综合BL-MMT/IIR/EPDM复合材料的力学性能及耐热氧老化性能,BL-MMT的填充量30份为宜。     

2,5-二甲基-2,5-双(叔丁基过氧基)己烷对三元乙丙橡胶/乙烯辛烯共聚物共混胶动态性能及耐热老化性能的影响

本文采用橡胶加工性能分析仪(RPA)分析了2,5-二甲基-2,5-双(叔丁基过氧基)己烷(DBPH)对三元乙丙橡胶/乙烯辛烯共聚物共混胶(EPDM/POE)动态性能及耐热老化性能的影响,结果表明,不同DBPH用量的混炼胶的动态性能之间差异比较小,而硫化胶因交联密度不同,动态性能差异较大。EPDM/POE混炼胶和硫化胶的储能模量随频率的升高而增大,随应变及温度的升高而减小;混炼胶的损耗因子随着频率的升高而降低,随应变及温度的升高而增大;硫化胶的损耗因子对频率的依赖性不明显,随着应变的升高而增大,随温度的升高而降低。不同DBPH用量的硫化胶经过RPA的无氧高温老化后,损耗因子增大;当DBPH为3.5质量份数时,硫化胶的损耗因子在老化前后都较小。     

IIR/EPDM并用硫化胶压缩永久变形性能的研究

研究了IIR／EPDM的并用比例、炭黑品种与黑用量、硫黄用量、促进剂CZ用量对IIR／EPDM并用硫化胶压缩永久变形的影响。结果表明：IIR／EPDM并用比例为80／20时,硫化胶具有较好的综合力学性能;在所研究的填充补强体系中,ISAF能够赋予硫化胶较好的耐压缩性能,适宜用量为50份;IIR／EPDM并用硫化胶的压缩永久变形在硫黄用量为0．5－1．0份较好;在研究的范围内,促进剂CZ的用量对IIR／EPDM并用硫化胶的压缩永久变形影响不大。     

IIR/EPDM共混硫化胶拉伸断裂行为的研究

使用SEM分析方法研究了生胶共混比、炭黑种类及其用量等因素对IIR/EPDM共混硫化胶拉伸断裂行为的影响.结果表明:当IIR/EPDM共混比为80/20时,所得硫化胶的拉伸强度较好,断面具有非常强的立体感;用结构性较高的炭黑和沉淀法白炭黑分别补强的硫化胶断面均较为粗糙;用结构性较低的炭黑补强的硫化胶断面接近"镜面";当炭黑用量由40份增加到90份时,IIR/EPDM硫化胶的断裂依次表现为屈服断裂、块状剥离、裂纹扩展3种形式.     

配方因素对CM/EPDM并用胶性能的影响

研究氯化聚乙烯橡胶(CM)和EPDM用量及硫化体系对CM/EPDM并用胶性能的影响.结果表明,随着CM用量的增大,并用胶交联密度降低,拉伸强度增大;随着EPDM用量的增大,并用胶t90缩短,撕裂强度减小;硫黄硫化体系的硫化效率较低,并用胶撕裂强度和拉断伸长率较大;过氧化物硫化体系硫化效率适中,并用胶综合物理性能最好;噻唑类硫化体系的硫化效率最高,并用胶拉伸性能和耐热空气老化性能良好.     

氟橡胶/三元乙丙橡胶并用胶的性能

研究了不同并用比(质量比)时氟橡胶(FKM)/三元乙丙橡胶(EPDM)并用胶动态硫化和静态硫化后的低温性能、物理机械性能、耐老化性能和热稳定性,并用扫描电子显微镜表征了并用胶.结果表明,当并用比为30/70时,并用胶有较好的相容性;EPDM可以改善FKM的低温性能;随着EPDM用量的增加,并用胶的拉伸强度及邵尔A硬度降低;动态硫化FKM/EPDM并用胶比静态硫化FKM/EPDM并用胶具有更好的耐老化性能,但老化前前者的拉伸强度稍低于后者;FKM/EPDM并用胶的热稳定性优于纯EPDM;静态硫化FKM/EPDM并用胶中片层现象严重,动态硫化FKM/EPDM并用胶的EPDM包覆在FKM中,但相畴偏大.     

HMPIB相对分子质量和用量对IIR/HMPIB并用胶性能的影响

研究高相对分子质量聚异丁烯(HMPIB)的相对分子质量和用量对丁基橡胶(IIR)/HMPIB并用胶性能的影响。结果表明:随着HMPIB用量增大,并用胶的门尼粘度降低,加工性能改善;高相对分子质量的HMPIB对并用胶拉伸强度和撕裂强度的增强作用显著;相同交联密度水平下,与全IIR硫化胶相比,添加20份HMPIB的并用胶拉伸性能提高约20%,因此在IIR/HMPIB并用胶配方设计时,应适当增大硫化体系用量。     

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.     

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。