纸板类儿童卡书抗弯曲性能影响因素研究

文章针对四种制备儿童卡书的卡纸进行研究,分析了卡纸纤维结构类型和表面粗糙度对儿童卡书变形度的影响。对水性胶粘剂固含量与儿童卡书弯曲度的关系研究发现胶粘剂固含量在60%~65%时,制备的卡书抗弯曲性能较好。此外,研究发现后处理环境条件选用温度23±3℃,湿度50±5%的标准条件,后处理时间为1个月左右得到的儿童卡书的弯曲变形度最小。     

固相萃取-高效液相色谱法测定水中灭草松、莠去津和2,4-滴

采用固相萃取富集-高效液相色谱法[1]分析地表水与饮用水中的灭草松,莠去津与2,4-滴。液相色谱条件为V甲醇∶V纯水=60∶40、流速为0.8 mL/min、柱温为30℃、检测波长为225 nm。灭草松、莠去津、2,4-滴检出限分别为0.002 5、0.000 2、0.002 5mg/L,回收率分别为85%-115%、80%-120%和85%-115%。该方法较样品衍生化后用气相色谱法测定简便,可实际应用于水质检测工作。     

掺纳米Al2O3的纳米ZrO2(4Y)固体电解质的电性能

以纳米ZrO2(4Y)粉和纳米Al2O3粉为原料, 单轴成型, 1 200, 1 300 ℃无压烧结. 对掺不同质量分数(0.0～5.0%)Al2O3的ZrO2(4Y)烧结体, 用XRD, SEM和TEM研究了相组成和微观结构. 在不同温度下(300～1 000 ℃)测试了交流阻抗谱, 发现掺很少量的纳米Al2O3可降低ZrO2(4Y)的晶粒电阻. 但随着Al2O3掺入量的增加, 晶界电阻增大, 晶粒电阻也有所回升. 晶粒和晶界电导活化能则随Al2O3掺入量的变化不大. 对1 200 ℃,2 h烧结样品, 在1 000 ℃时, 掺0.5% Al2O3的ZrO2(4Y)样品有最大电导率, 为3.8×10-2Ω-1·cm-1.     

海上平台变压器房通风口防水设计

海上平台变压器房的通风量一般都很大,在大风雨天气,雨水通过送风口被风机吸入房间的情况时有发生。文章针对变压器房通风口在平台的不同位置,给出了不同的防水设计方法,对布置在上层甲板的露天变压器房,介绍了通风口做防水风箱的新颖做法,由于其防水可靠,简单易行,很值得推荐。     

An investigation on the graphitic carbon nitride reinforced polyimide composite and evaluation of its tribological properties

This article presented a novel application for the graphitic carbon nitride (g‐C₃N₄), which was used as nanofillers to improve the tribological properties of polyimide (PI). The composite based on PI and g‐C₃N₄ was prepared by mechanical mixing process and hot compression molding process. The characterizations of g‐C₃N₄ and PI/g‐C₃N₄ composites were investigated by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, and scanning electron microscopy. Friction and wear tests were carried out using UMT‐2 reciprocating tribo‐tester against stainless steel ball under dry friction. The results showed that the amount of g‐C₃N₄ was decisive to the tribological properties of PI/g‐C₃N₄ composites. The optimal tribological properties occurred when the amount of g‐C₃N₄ was 10 wt %, which showed the smallest friction coefficient and the lowest wear rate. Furthermore, this work provided an example of application for the g‐C₃N₄ as the excellent nanofiller in polymer matrix composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45403.     

Processing-Mechanical Property Relationship of Thin Microcellular PET Sheet Prepared by Compression Molding

This article presented processing-mechanical property relationship of thin microcellular poly(ethylene terephthlate) (PET) sheet prepared by compression molding. The results showed that the saturation time and the lower-plate temperature had more effects on the mechanical property. The upper-plate temperature and the PET thickness also had some effects on the mechanical property. The upper-plate temperature had more pronounced effect on the specific tensile strength than on any other mechanical parameters. Besides, there was little dependence of the mechanical property on the saturation pressure and the blowing agent content.     

聚苯并噁嗪树脂合成及其高性能化改性研究进展

首先介绍了聚苯并噁嗪树脂(PBZ)的性能和应用,概述了合成PBZ树脂的反应机理以及溶液法、熔融法及悬浮法合成PBZ工艺的优缺点,简述了PBZ树脂固化机理和工艺,回顾了PBZ树脂的高性能化改性手段和PBZ纳米复合材料的国内外研究进展,分析了具有不同分子结构、通过不同加工手段以及含有不同纳米填料改性的PBZ树脂性能改善情况。得出了目前针对PBZ树脂改性研究的重点,并对PBZ树脂的研究与应用做出展望。     

Sintering behavior and morphology control of porous Al2O3-SiO2 ceramics for radome applications

Ceramics from porous Si₃N₄ and its derivatives SiAlON and Si₂N₂O were once considered the most promising high-temperature wave-transmitting materials. However, their large-scale application in the field of radomes is greatly restricted due to their poor oxidation resistance, high preparation costs, and expensive raw materials. Therefore, the development of low-cost porous oxide ceramics remains of significant interest to the field of high-temperature wave transmission. Surprisingly, mullite ceramics, which are representative of the Al₂O₃-SiO₂-system of ceramics, are ultra-low-cost materials with the potential to replace ceramics from Si₃N₄ and its derivatives. In this paper, integrated porous Al₂O₃-SiO₂-system ceramics were successfully prepared for load-bearing/wave-transmitting applications, using inexpensive calcined kaolin and alumina powder as the main raw materials. Calcined kaolin can provide seeds for the growth and development of mullite crystals in the ceramic system. High-strength and high-porosity ceramics were obtained with the mullite morphology controlled through the molar ratio of Al₂O₃ to SiO₂ and the resulting content of mullite seeds. With increasing of mullite seed content, the length and radial width of mullite whiskers with “interlocking structure” gradually change from rod-shaped “long and thick” to needle-like “short and thin.” The prepared porous Al₂O₃-SiO₂ ceramics have high flexural strength, fracture toughness, and good dielectric properties.     

Thermally insulating GdBO3 ceramics with neutron shielding performance

There is an urgent demand for multifunctional insulation materials with neutron shielding ability that can be particularly used in the nuclear energy system. GdBO₃ ceramics are one of the candidates for such materials. In this study, GdBO₃ ceramics were successfully synthesized using a simple solid-phase method. The effect of boric acid content on the micro and macro properties of GdBO₃ ceramics was explored. The experimental results indicate that the thermal conductivity of the resulting GdBO₃ ceramics ranged from .12 to .68 W/(m⋅K), and lower thermal conductivity was achieved with smaller pore size and higher apparent porosity of the sintered product. Moreover, the mechanical properties of the samples in multiple temperature ranges can be improved by increasing boric acid content. Finally, neutron shielding permeability study, performed on the samples in different thicknesses, reveal that GdBO₃ ceramics possessed excellent neutron shielding performance (NSP). The obtained results manifest that GdBO₃ ceramics with outstanding heat insulation and NSP have a potential application in a nuclear reactor.