改性EPDM与二烯类橡胶的共硫化

在引发剂存在下用高温密炼机制得了马来酸酐(MA)改性EPDM。红外光谱分析表明,MA与EPDM分子发生化学结合。研究了MA改性EPDM与SPR、NR和NBR共混硫化胶的性能。与未改性EPDM相比,MA改性明显改善了EPDM与二烯类橡胶的共硫化性和共混硫化胶的力学性能。     

汽车行业用橡胶型材

正EPDM有独特的机械性能和化学性能,因此在工业领域应用广泛。EPDM拥有优异的耐候性、耐臭氧性、耐酸碱性及较好的机械性能。将塑料与高烯烃橡胶共混受到重视,因为共混物应用范围非常广泛,通过加入交联剂改性这些共混物的结构。聚乙烯的DCP交联反应服从一级反应动力学,与过氧化物浓度无关。将热稳定剂加入到低密度聚乙烯和聚丙烯/EPDM共混物体系中,能有效降低过氧化物硫化过程中其热氧老化     

EPDM-NBR共混弹性体的相容性和热稳定性

将三元乙丙橡胶（EPDM）与丁腈橡胶（NBR）共混。共混物的形态随着加入少量改性EPDM而得到改善。特性粘度、介电常数测量以及SEM照片均显示出改善了这些橡胶的相容性。含有改性EPDM的共混物热老化后机械性能与加成规则出现正偏差。通过对各种共混比的EPDM-NBR进行研究，发现共混比为25／75并以胺化环氧EPDM作为相容剂时，表现出最佳的机械性能．耐热性能和耐UV照射稳定性能。     

纳米莫来石填充PP/EPDM共混物的脆韧转变

制备了含纳米莫来石的三元乙丙橡胶(EPDM)和马来酸酐接枝三元乙丙橡胶(EPDM-g-MAH)母料,研究了纳米莫来石对聚丙烯(PP)/EPDM和PP/EPDM-g-MAH共混物脆韧转变的影响。结果表明:纳米莫来石的加入使PP/EPDM和PP/EPDM-g-MAH共混物的脆韧转变提前,尤其在纳米莫来石用KH-550改性后,PP/EPDM共混物发生脆韧转变时EPDM的含量由15%降至10%;在橡胶相含量相同时,加入纳米莫来石后共混物的弹性模量和拉伸强度略有下降,而断裂伸长率显著下降。     

硅酸盐纳米短纤维增强三元乙丙橡胶复合材料的结构与性能

用硅烷偶联剂改性针状硅酸盐(FS)与三元乙丙橡胶(EPDM)机械共混,制备了EPDM/改性FS复合材料,研究了FS在EPDM中的分散性,考察了偶联剂和改性FS用量、FS所含自由水对复合材料力学性能和各向异性的影响.结果表明,经过偶联荆改性的FS能够解离成纳米纤维均匀分散于EPDM中,每100份FS的偶联刺最佳用量为24份;EPDM/改性FS复舍材料具有短纤维增强橡胶复合材料的应力-应变特征和力学性能的各向异性,且随改性FS和偶联剂的用量增加,这种力学行为更加明显;FS中所舍自由水对复合材料的常温和高温拉伸性能有明显影响.     

EPDM在材料改性方面的应用研究进展

文章介绍了国内外EPDM在材料改性方面的应用研究进展,分析了在EPDM共混改性过程中橡胶含量、加工工艺对材料性能的影响,最后还展望了该领域的发展趋势。     

氯化聚乙烯橡胶/废旧三元乙丙橡胶胶粉共混发泡材料的研究

研究氯化聚乙烯橡胶(CM)/废旧三元乙丙橡胶(EPDM)胶粉共混发泡材料的性能,并采用活化剂420等对废旧EPDM胶粉进行活化改性,考察废旧EPDM胶粉改性对共混发泡材料的影响。结果表明:随着废旧EPDM胶粉用量的增大,共混发泡材料的门尼粘度增大,邵尔C型硬度减小,发泡倍率先增大后减小,发泡收缩率减小;废旧EPDM胶粉改性后,共混发泡材料的门尼粘度变化不大,M_H-M_L值增大,发泡倍率略有减小,但物理性能和发泡收缩率改善,且泡孔结构更密实、更完整。     

超细全硫化粉末NBR/EPDM共混物的结构与性能

试验研究超细全硫化粉末NBR（UFPNBR）／EPDM共混物的硫化特性、相态结构、动态力学性能，加工性能及物理性能。UFPNBR粒子加入EPDM中明显影响了EPDM的硫化性能，UFPNBR／EPDM共混物采用过氧化物硫化体系硫化效果较好；透射电子显微镜和扫描电子显微镜观察表明，UFPNBR粒子在UFPNBR／EPDM共混物中始终为分散相，但在EPDM基体中没有分散成预期的纳米尺寸；动态力学热分析结果显示，共混物存在两个玻璃化温度，呈两相结构且界面结合较弱；橡胶加工分析仪分析结果表明，UFPNBR粒子在EPDM基体中形成了填料网络结构，使共混物的流动性能变差；UFPNBR对EPDM有一定补强作用，但补强作用不如传统的纳米无机填料。     

三元乙丙橡胶共混改性的研究进展

介绍了三元乙丙橡胶(EPDM)的优缺点.综述了近年来三元乙丙橡胶与其他橡胶共混改性的研究进展,总结了提高各种EPDM并用胶性能的方法,以及各种EPDM并用胶的应用领域.     

过氧化二异丙苯（DCP）在mEPDM／PP复合材料体系中的影响

本文采用过氧化二异丙苯为硫化剂对三元乙丙橡胶(EPDM)/聚丙烯(PP)进行了共混改性研究。通过改变体系中硫化剂过氧化二异丙苯(DCP)的量,对体系的力学性能进行了研究。结果表明:EPDM橡胶的动态硫化,大幅度提高了EPDM与PP体系的力学、加工性能;使其具有高流动,高抗拉伸性能。DCP的用量对PP/EPDM共混体系力学性能的影响较复杂,除了断裂伸长率,其它力学性能都有下降。应依据产品的不同要求,采用相应的用量比例。     

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。     

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。     

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。     

丁腈橡胶的伏安特性与功率特性的研究

本文对乙炔碳黑填充丁腈橡胶（NBR）的伏安特性及其功率特性进行了研究,分析了丁腈橡胶在交、直流电场下的导电机理,并对环境温度变化时的丁腈橡胶的功率及功率与电压的变化规律提出了相应的关系式,同时对导电丁腈橡胶的物理机械性能进行了研究与测定。