导电聚氨酯泡沫材料研究进展

从使用不同导电填料（炭黑、碳纳米管、石墨、金属、有机填料等）制备导电聚氨酯泡沫（PUF）材料的角度进行分析,总结了添加不同导电填料的复合泡沫制备方法以及对泡沫材料性能的影响,并论述了导电PUF材料在压阻材料、吸波材料、电磁屏蔽材料以及电极材料等领域的应用。分析表明,通过添加导电填料,可以改善PUF的静电现象,提高防静电、导电等性能并拓宽PUF材料的应用领域。     

The comparative study of biocomposites based on hydrochar and chitosan-modified urea-formaldehyde resins

To provide new insight into the field of urea-formaldehyde (UF) adhesives science, in this work, for the first time, UF resin was modified with hydrochar of spent mushroom substrate (HCUF) and chitosan (CHUF) to investigate the effect of these bio-fillers on the hydrolytic and thermal stability of in situ prepared UF resins. The characterization of the modified UF biocomposites was performed using X-ray diffraction analysis (XRD), Fourier transforms infrared spectroscopy (FTIR), non-isothermal thermogravimetric analysis (TG), differential thermal gravimetry (DTG), and differential thermal analysis (DTA). Scanning electron micrographs (SEM) of the CHUF and HCUF biocomposites show a spherical structure that differs from each other because the surface of the CHUF biocomposite has pronounced pores that form a network structure. With its hydroxyl and amino groups, chitosan bonding to UF resin through hydrogen bonds, which is confirmed by FTIR analysis. The content of free FA in CHUF biocomposite is 0.06%, while that of HCUF is higher and amounts to 0.48%. The content of released FA in both modified UF biocomposites was similar (2.5% and 2.8% for CHUF and HCUF, respectively). The hydrolytic stability of CHUF is slightly higher compared to the HCUF biocomposite. Thermal analysis shows that the CHUF is thermally more stable because it starts to decompose at a slightly higher temperature than the HCUF biocomposite.     

Influence of shear deformation on the electrical and rheological properties of combined filler networks in polymer melts: Carbon nanotubes and carbon black in polycarbonate

The influence of shear on combined filler systems containing multi-walled carbon nanotubes (MWNT) and carbon black (CB) in polycarbonate (PC) melts was investigated by time-resolved combined rheological and electrical measurements. Samples with different MWNT/CB ratios and total carbon filler contents (0.25–10 wt%) were studied. The morphology of the filler network was analyzed by TEM and SEM in charge contrast mode whereby a combined MWNT/CB filler network is indicated.     

Water permeability of pigmented waterborne coatings

Coatings are used in a variety of applications. Last decades more and more coating systems are transforming from solvent to waterborne coating systems. In this study the influence of pigments on the water permeability of a waterborne coating system is studied, with special interest in the possible interfacial layer of additives around the pigments. In our study an acrylate based binder is mixed with different glass sphere concentrations and sizes. Subsequently, the coating permeability is studied through wet-cup experiments and water uptake in the coating, either on a glass substrate or on wood, is monitored with NMR. These experiments show that water is absorbed more quickly by coatings containing glass spheres. From the experimental results it can be concluded that an interface layer around the pigment particles facilitates water migration and increases the effective diffusion. A modification of the effective medium theory is used to describe the observation and good agreement between experiments and theory is obtained. Both theory and experiment show that in a coating a layer around the pigments facilitates water transport and increases the effective diffusion constant.     

Model Adherend Surface Effects on Epoxy Cure Reactions

Adherend surface effects on the amine cure of epoxy resins were investivated using finely divided aluminum oxide as high surface area models for aluminum. Calorimetric analysis of simplified crosslinking systems revealed significantly faster reactions which led to lower glass transition temperature materials for activated aluminum oxide filled samples. A monofunctional amine and epoxy were then utilized to obtain soluble reaction products amenable to molecular characterization. These studies similarly showed an increase in the rate of epoxy consumption in the presence of activated aluminum oxide which was attributed to both an increase in the rate of amine addition to epoxy as well as to epoxy homopolymerization. The latter was not observed in the unfilled mixtures. Such changes in reaction mechanism at the adherend surface have implications for the strength and durability of actual adhesive bonds.     

彩色氯化聚乙烯电缆护套胶料的研制

研究以氯化聚乙烯橡胶(CM)为主体材料制备彩色电缆护套胶料。结果表明,填料采用煅烧陶土/纳米碳酸钙/超细滑石粉白色填料体系(并用比45/30/25)、硫化体系采用硫化剂DCP/助交联剂TAIC硫化体系,制备的彩色电缆护套胶料各项性能优异,满足使用要求。     

Development of a Coconut- and Palm-Based Fat Blend for a Cookie Filler

Thirteen fat blends intended for cookie filler (CF) production that consist of 20–70 % palm mid-fraction (PMF), 20–70 % virgin coconut oil (VCO), and 0–10 % palm stearin (POs) were developed based on the solid fat contents (SFC) of the fat portions extracted from five commercial CF samples: A, B, C, D, and E. A mixture design was applied for fat blend optimization, and the combination that best approached the target SFC values was composed of 70 % PMF, 20 % VCO, and 10 % POs. The optimized coconut- and palm-based fat blend (O-CP) exhibited a steeper SFC profile, with 8.2 % (±0.2) SFC at 25 °C (room temperature) and 0.2 % (±0.2) SFC at 37 °C (body temperature); lower slip melting point of 34.0 °C (±0.0); and a lower iodine value (IV) of 40.25 g/100 g (±1.04). In addition, O-CP contained higher proportions of medium-chain fatty acids (MCFA) and lauric acid (C12:0) of 3.2 % (±0.18) and 9.7 % (±0.43), respectively. In terms of its thermal profile, O-CP showed no significant difference in terms of its crystallization range, 49.7 °C (±2.66) with the exception of sample C, but it exhibited a smaller melting range, 65.8 °C (±1.47), compared to the fat portions of the commercial samples. The ranges represented the span between the onset and offset temperatures of both crystallization and melting profiles as determined by differential scanning calorimetry.     

空心玻璃微珠增强泡沫材料的研究和应用进展

空心玻璃微珠是一种新型无机填料,经表面改性后,与发泡基体复合,制备新型复合泡沫材料。同传统发泡材料相比,该复合材料质轻且机械性能优异,在航天航空以及深海开发等领域,特别是制备浮力材料方面,应用前景广阔。文章综述了空心玻璃微珠表面改性方式、空心玻璃微珠/发泡体复合材料的发泡方法和成型工艺,在此基础上对近年来国内外研究和应用现状进行了介绍。     

Properties of Ferrite-Filled Natural Rubber Composites

Nickel zinc ferrite (Ni-ZnFe₂O₄)-filled natural rubber (NR) composite was prepared at various loading of ferrite. The tensile properties included in this study were tensile strength, tensile modulus and elongation at break. The tensile strength and elongation at break of the composites increased up to 40 parts per hundred rubber (phr) of ferrite and then decreased at higher loading whereas the tensile modulus was increased gradually with increasing of ferrite loading. Scanning electron microscopy (SEM) was used to determine the wettability of filler in rubber matrix. From the observation, the increase of filler loading reduced the wettability of the filler. Thermal stability of the composites was conducted by using a thermogravimetry analyser (TGA). The incorporation of ferrite in NR composites enhanced the thermal stability of NR composites. The swelling test results indicate that the swelling percentage of the composites decreased by increasing of ferrite loading. The initial permeability, μ_i and quality factor, Q of magnetic properties of NR composites achieved maximum value at 60 phr of ferrite loading for frequency range between 5000–40,000 kHz. The maximum impedance, Z _max of the NR composites was at the highest value at 80 phr ferrite loading for frequency range between 200–800 MHz.     

高导热低介电性单组分EP灌封胶的研制

以双酚A型环氧树脂(EP)为基体树脂、线性酚醛树脂(PF)和双氰胺为固化剂、烯丙基缩水甘油醚(AGE)为活性稀释剂、2-乙基-4-甲基咪唑为固化促进剂、氮化硼(BN)和三氧化二铝(A12O3)为导热填料,制备单组分EP灌封胶。采用单因素试验法优选出制备灌封胶的最佳工艺条件,并对灌封胶的导热系数、介电常数、剪切强度和玻璃化转变温度(Tg)等进行了表征。结果表明:制备高导热低介电性单组分EP灌封胶的最佳工艺条件是m(EP)∶m(PF)∶m(活性稀释剂)∶m(BN)=10∶3∶2∶6、w(固化促进剂)=w(流平剂)=0.5%(相对于EP质量而言)和固化条件为"120℃/0.5 h→170℃/1 h",此时其剪切强度为42.37 MPa、介电常数为4.6和导热系数为1.214 W/(m.K)。