丁基橡胶热氧老化性能的研究

通过改变配方中酚醛树脂的用量和卤素给予体的种类及用量,探讨了各变量下对IIR硫化特性和耐热氧老化性能的影响。实验表明,老化前后,300%定伸应力和硬度均有所提高,而拉伸强度、撕裂强度和拉断伸长率有不同程度下降。在树脂用量为8份、CIIR用量为11份、BIIR用量为9份时,各配方的IIR硫化胶性能最好。     

硫化剂B-L01在IIR中的应用

研究硫化剂B-L01在IIR中的应用效果.结果表明,采用硫化剂B-L01/树脂硫化体系的IIR硫化胶具有良好的物理性能、耐热空气和耐蒸汽老化性能;采用硫化剂B-L01/树脂硫化体系的IIR硫化胶性能可达到或超过采用树脂硫化体系的CIIR和BIIR硫化胶的水平。     

丁基橡胶热氧老化性能的研究

通过改变配方中酚醛树脂的用量和卤素给予体的种类及用量，探讨了各变量下对IIR硫化特性和耐热氧老化性能的影响。实验表明，老化前后，300％定伸应力和硬受均有所提高，而拉伸强度、撕裂强度和断裂伸长率有不同程度下降。在树脂用量为8份，CIIR用量为11份，BIIR用量为9份时，各配方的IIR硫化胶性能最好。     

IIR/EPDM并用胶性能的研究

对IIR/EPDM并用胶性能进行试验研究。结果表明,在EPDM用量不超过30份时,随着EPDM用量的增大,IIR/EPDM并用胶的加工性能、焦烧时间和硫化速度变化不大;与IIR硫化胶相比,IIR/EPDM并用胶的交联密度减小,拉伸强度和拉断伸长率增大,撕裂强度略有提高,长期耐热老化性能相当,-10～ 25℃时的损耗因子小于IIR硫化胶,25～200℃时的损耗因子大于IIR硫化胶。     

HMPIB硫化胶及IIR/HMPIB共混胶老化性能的研究

研究了HMPIB硫化胶及IIR/HMPIB硫化胶的力学性能及耐热空气老化、耐臭氧老化、耐酸腐蚀的性能。结果表明:HMPIB硫化胶有较高的拉伸强度、撕裂强度、扯断伸长率,但定伸应力较低,具有良好的耐臭氧老化和耐酸腐蚀性能;IIR中加入HMPIB,随着用量的增加,硫化胶的拉伸强度、撕裂强度、扯断伸长率增加,定伸应力降低。HMPIB能使IIR的耐臭氧、耐酸腐蚀性能得到提升,但不利于IIR的耐热性能。     

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。     

影响CR/CIIR硫化胶耐热老化性能的因素

研究了共混比、硫化体系、炭黑品种及用量、软化剂种类等对CR/CIIR硫化胶耐热老化性能的影响。结果表明,100℃×48h热老化后,CR/CIIR硫化胶的力学性能保持率随CIIR用量的增加而提高;采用TCY/树脂复合硫化体系硫化的CR/CIIR力学性能保持率相对较高;采用N550炭黑补强的硫化胶耐热老化性能良好,但用量不宜超过60份;软化剂对硫化胶的耐热老化性能也有一定影响。     

硫化体系对氢化丁腈橡胶/氯丁橡胶并用胶性能的影响

研究硫化体系对氢化丁腈橡胶(HNBR)/氯丁橡胶(CR)(并用比70/30)并用胶硫化特性、物理性能和耐热老化性能的影响。结果表明:采用硫化剂DCP/助硫化剂TAIC硫化体系时,HNBR/CR并用胶的焦烧时间较长,拉断伸长率较大,拉断永久变形较小,耐热老化性能较好;当硫化剂DCP用量为5份、助硫化剂TAIC用量为3份时,并用胶的硫化速率较大,加工安全性、耐油性能、综合物理性能和耐热老化性能较好。     

炭黑填充IIR胶料耐热老化性能的研究

研究了不同硫化体系以及其它配方因素对丁基硫化胶耐热老化性能的影响。以硫化胶老化后的力学性能保持率作为评价胶料耐热老化性能的参数。研究结果表明 :经过 160℃× 2 4h热空气老化后 ,树脂硫化丁基胶的力学性能保持率比硫黄硫化胶和给硫体硫化胶高 ;炭黑的品种、防老剂的种类、操作油的品种、Zn0的用量对丁基硫化胶的力学性能和耐热老化性能都有一定影响     

低锌活性剂SA-1替代氧化锌在丁苯橡胶胶料中的应用

采用低锌活性剂SA-1作为丁苯橡胶（SBR）胶料的硫化活性剂,研究其用量对SBR硫化胶物理性能、耐热空气老化性能和动态力学性能的影响,同时与普通氧化锌997进行对比。结果表明：活性剂SA-1在SBR基体中的分散性优于氧化锌997;活性剂用量较大（3～5份）时,采用活性剂SA-1的SBR硫化胶具有较出色的物理性能和耐热空气老化性能;随着活性剂SA-1和氧化锌997用量的减小,SBR硫化胶的物理性能和耐热空气老化性能均有下降,与氧化锌997相比,活性剂SA-1可以在用量更小时保持SBR硫化胶的物理性能;采用活性剂SA-1的SBR硫化胶具有更好的抗湿滑性能,同时滚动阻力无明显增大。     

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。