氧化/水解稳定性优异的聚异丁烯基聚氨酯的合成与表征（英文）

设计合成了不同聚异丁烯含量的聚异丁烯基聚氨酯材料,并对其结构、力学性能、阻尼性能、热性能和微观形貌分别进行了傅里叶变换红外光谱、动态热机械、扫描电子显微镜和热重分析。结果表明,以聚异丁烯为软段的聚异丁烯基聚氨酯材料,在聚异丁烯质量分数为60%时具有最佳的力学性能和阻尼性能,最大阻尼因子可以达到0.83,且阻尼因子大于0.3的温域从-60℃到27℃。此外还研究了聚异丁烯基聚氨酯的耐氧化/水解稳定性,将聚异丁烯基聚氨酯浸泡在35%的硝酸溶液中18 h,定量分析浸泡前后其拉伸强度和拉伸模量的变化情况,结果表明聚异丁烯基聚氨酯材料具有优异的耐氧化/水解稳定性。     

聚异丁烯基弹性体的研究进展

综述了聚异丁烯及异丁烯与异戊二烯、对甲基苯乙烯、苯乙烯和四氢呋喃等单体共聚的异丁烯基弹性体的合成及加工应用的最新进展,展望了聚异丁烯基弹性体的发展趋势。     

聚异丁烯预聚物

叙述了聚异丁烯遥爪预聚物的发展情况,着重介绍了端羟基遥爪聚异丁烯材料的性能;并与聚氨酯材料相比较;说明了聚异丁遥爪预聚物的主要应用前景。     

高耐介质聚天门冬氨酸酯型聚氨酯地坪涂料制备及其力学性能评价

采用聚天门冬氨酸酯与脂肪族异氰酸酯合成聚氨酯材料，对影响聚氨酯性能的交联密度、α值、阻燃剂、耐磨助剂等因素进行研究，并考察了聚氨酯材料的长期耐介质性能。测试发现，通过调节三官能度异氰酸酯含量，可得到兼具较高力学性能和弹性的聚氨酯材料，添加阻燃剂后材料的力学性能和拉伸强度均有所降低，添加少量的微蜡粉可提高材料的耐磨性；同时本材料体系还具有优异的耐介质性能，在水、海水、酸、碱和油等中浸泡10个月后，材料的拉伸强度和断裂伸长率的保留率均大于98%；浸泡20个月后，材料的力学性能保留率基本大于75%。     

异氰酸酯类型对蓖麻油基聚氨酯性能的影响

以4,4-二环己基甲烷二异氰酸酯(HMDI)、异氟尔酮二异氰酸酯(IPDI)、蓖麻油基多元醇为主要原料,在不添加扩链剂及交联剂的情况下,采用两步法(预聚体法)制备了蓖麻油基聚氨酯材料。通过动态力学性能(DMA)、热失重(TGA)及力学性能测试等手段对聚氨酯材料的性能进行测试,探究异氰酸酯类型及溶剂对蓖麻油基聚氨酯材料性能的影响。结果表明:HMDI型聚氨酯材料的拉伸强度与耐热性能均优于IPDI型聚氨酯材料,但IPDI型聚氨酯材料的断裂伸长率相对较高;采用丙酮作为溶剂会在降低材料拉伸强度与耐热性能的同时提高材料的断裂伸长率;蓖麻油基聚氨酯材料具有较高的损耗因子(tanδ),因此其具有优异的阻尼性能,有效阻尼温域集中于常温区域。     

微晶纤维素对HMDI型聚氨酯弹性体性能的影响

以4,4'-二环己基甲烷二异氰酸酯(HMDI)、聚醚多元醇和1,4-丁二醇(BDO)为主要原料,填料为微晶纤维素(MCC),采用共混方法合成制备了一系列聚氨酯弹性体,研究了微晶纤维素对HMDI型聚氨酯弹性体性能的影响。结果表明:MCC的加入未影响聚氨酯的分子振动;拉伸强度和断裂伸长率随微晶纤维素含量增加先升高再降低,在MCC添加量为15%时,材料的力学性能达到最大;MCC的加入在一定程度上可提高聚氨酯材料阻尼因子,拓宽阻尼温域;MCC的加入提高聚氨酯弹性体的热稳定性。     

聚酯型聚氨酯阻尼材料的改性研究

采用接枝、嵌段及交联的方法对聚酯型聚氨酯(PU)阻尼材料进行改性并对其阻尼性能和力学性能进行研究.结果表明,PU材料的阻尼性能随接枝率增加而明显提高;当接枝率10%时,tanδmax为0.84,tanδ>0.3的阻尼温域为0.8～61.6℃,拉伸强度19.6 MPa,撕裂强度为27.0 kN/m,伸长率500%,是综合...     

汽油清净剂的发展历程及现状简述

介绍了燃油清净剂的发展历程,着重介绍了目前发达国家普遍使用的以聚异丁烯胺为主剂的第四代产品的合成方法,以及以聚异丁烯基苯酚曼尼希加合物为主剂的第五代产品的开发研究。     

高强度浇注聚酯型聚氨酯阻尼材料的研究

以不同种类的聚酯多元醇为软段,2,4-甲苯二异氰酸酯和3,3'-二氯-4,4'-二氨基二苯甲烷为硬段,合成了聚氨酯(PUR)阻尼材料.考察了不同软段结构、硫化温度和测试频率对PUR材料阻尼性能和力学性能的影响.结果表明,所制备的可室温硫化并具有优异力学性能的PUR阻尼材料,其拉伸强度达到12.9 Mpa,1 Hz时的tanδmax达到0.79,tanδ>0.3的阻尼温域达到45.5℃(-13.0～32.5℃).     

温度对聚氨酯固化材料力学性能的影响

为探究不同温度下聚氨酯固化道床的适应性,研究了温度对聚氨酯固化材料拉伸性能、黏结性能和动态力学性能的影响。结果表明,在-60~70 ℃内,随着环境温度的降低,聚氨酯固化材料的拉伸模量、拉伸强度和黏结强度均逐渐增加,变形性能先增加后降低,且固化材料的黏结强度破坏均为内聚破坏;在-50 ℃左右,聚氨酯固化材料发生了玻璃化转变,当温度接近玻璃化转变温度时,固化材料的损耗因子较高,变形性能较好;随着聚醚多元醇相对分子质量的增加,聚氨酯固化材料的玻璃化转变温度降低,低温下聚氨酯固化材料的拉伸性能变化率越小;聚氨酯固化材料的性能能够满足不同温度下的使用需求,当在低温环境下服役的聚氨酯应优先选用相对分子质量较高的聚醚多元醇。     

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。