PPS/Al_2O_3导热复合材料的性能及其应用

以微米级三氧化二铝(Al2O3)为导热填料,制备了聚苯硫醚(PPS)/Al2O3导热复合材料,研究了硅烷偶联剂表面改性对PPS/Al2O3复合材料力学性能和导热性能的影响.研究表明,硅烷偶联剂时Al2O3的表面改性提高了PPS/Al2O3导热复合材料的力学性能,且材料的热导率随着Al2O3含量的增加而增大,当Al2O3的质量分数为70%时,未改性和改性Al2O3填充PPS导热复合材料的热导率分别达到2.279 W/(m·K)和2.392 W/(m·K),后者的热导率在Al2O3含量较高时偏离Agari理论曲线.SEM分析表明,改性Al2O3在PPS中分散均匀,两者结合紧密.经应用研究表明,PPS/改性Al2O3质量比为40/60的导热复合材料完全可满足发动机零部件、高耐热电子元器件对材料导热与力学性能的要求.     

基于数字锁相原理的GPS高精度同步时钟产生新方法

在分析时钟误差的基础上,根据全球定位系统(GPS)秒时钟无累计误差和晶振秒时钟无随机误差的特点,提出了一种利用GPS秒时钟同步晶振秒时钟实现高精度时钟的新方法.该方法根据数字锁相原理,通过测量GPS秒时钟与晶振秒时钟间的相位差来控制晶振秒时钟的分频系数,实时消除晶振秒时钟的累计误差,从而产生高精度秒时钟.实验结果表明,在GPS正常工作时能够保证其精度稳定在20 ns;GPS信号失效1 h的情况下,秒时钟精度仍能稳定在100 ns.根据此方法研制了具有较高性价比的高精度时钟发生装置,成功应用于行波定位系统中.     

基于DPT的非线性调频信号参数估计

将非线性调频（NLFM）信号建模为高阶多项式相位信号（PPS）模型,采用由低阶离散多项式变换（DPT）到高阶DPT的逆向定阶方法确定模型阶数,并在此基础上,给出一种正弦调频信号（SFM）的DPT参数估计算法,可以实现对载波频率、调制频率及调频系数的估计。该算法不受调频系数范围的限制,核心环节为延时相关和FFT。仿真表明当SNR≥6dB时,调频参数的均方根误差小于-10dB。采用ADI公司TS201S芯片作为处理器,算法运行时间为3.30603ms,能够满足一般实时处理的要求。     

Chemical surface functionalization of bulk poly (p-phenylene sulfide) yields a stable sulfonic acid catalyst

Catalytic materials are important in industrial chemistry; these materials must be inexpensive and easy to process as well as resistant to chemicals, heat and structural loads. Poly (p-phenylene sulfide) (PPS) is a widely used and exceptionally resistant thermoplast. We demonstrate that the superficial regions of polymerized bulk PPS can be sulfonated using either SO₃ or acetyl sulfate, yielding a solid core of unaltered PPS with a sulfonic acid-functionalized surface. The SO₃ method was the most efficient and achieved 0.9 mmol H⁺ per gram of polymer. We show that the sulfonated surfaces function as durable solid acid catalysts for the dehydration of ethanol to diethyl ether. We also develop a simple method for the formation of porous PPS structures based on compression molding and porogen leaching. Based on these results, we suggest that surface functionalization of bulk PPS can be used to develop a novel class of moldable, easily produced and durable heterogeneous catalysts.     

Conductive polymer composites with segregated structures

Conductive polymer composites (CPCs) have generated significant academic and industrial interest for several decades. Unfortunately, ordinary CPCs with random conductive networks generally require high conductive filler loadings at the insulator/conductor transition, requiring complex processing and exhibiting inferior mechanical properties and low economic affordability. Segregated CPC (s-CPC) contains conductive fillers that are segregated in the perimeters of the polymeric granules instead of being randomly distributed throughout the bulk CPC material; these materials are overwhelmingly superior compared to normal CPCs. For example, the s-CPC materials have an ultralow percolation concentration (0.005–0.1 vol%), superior electrical conductivity (up to 10⁶ S/m), and reasonable electromagnetic interference (EMI) shielding effectiveness (above 20 dB) at low filler loadings. Therefore, considerable progress has been achieved with s-CPCs, including high-performance anti-static, EMI shielding and sensing materials. Currently, however, few systematic reviews summarizing these advances with s-CPCs are available. To understand and efficiently harness the abilities of s-CPCs, we attempted to review the major advances available in the literature. This review begins with a concise and general background on the morphology and fabrication methods of s-CPCs. Next, we investigate the ultralow percolation behaviors of and the elements exerting a relevant influence (e.g., conductive filler type, host polymers, dispersion methods, etc.) on s-CPCs. Moreover, we also briefly discussed the latest advances in the mechanical, sensing, thermoelectric and EMI shielding properties of the s-CPCs. Finally, an overview of the current challenges and tasks of s-CPC materials is provided to guide the future development of these promising materials.     

湿法制备长碳纤维增强聚苯硫醚复合材料的性能

利用湿法浸渍工艺制备碳纤维和聚苯硫醚纤维的混合纤维坯料,经干燥、模压成型后,制得长碳纤维增强聚苯硫醚(LCF/PPS)复合板材。本文考察了水中碳纤维浓度、碳纤维含量和长度对复合板材冲击、弯曲等力学性能的影响,并通过SEM表征板材断面的形貌,分析碳纤维在树脂中的分散情况及对板材力学性能的影响。结果表明,在本实验体系中,当碳纤维在水中湿法分散的浓度为0.5g/L,长度和含量分别为9mm、45wt%时,可以得到高性能的LCF/PPS复合材料,冲击强度为49.1kJ/m2,弯曲强度和模量为178.51MPa和18.56GPa;从板材的冲击样条断面可以看到,碳纤维在树脂中的分散比较均匀,纤维与树脂的黏结性好。     

聚苯硫醚纤维的纺丝与改性

聚苯硫醚（PPS）纤维是一种新型的高性能合成纤维，具有优异的耐化学腐蚀性、热稳定性及优良的电绝缘性，机械强度与Nomex纤维相近。文章阐述了PPS纤维的特性、应用以及纺丝工艺参数的设定，并分析了其对PPS纤维的性能的影响，探讨了PPS纤维共混改性的方法与意义。     

Developing architecture for upgrading I&C systems of an operating nuclear power plant using a quality attribute-driven design method

This paper presents the architecture for upgrading the instrumentation and control (I&C) systems of a Korean standard nuclear power plant (KSNP) as an operating nuclear power plant. This paper uses the analysis results of KSNP's I&C systems performed in a previous study. This paper proposes a Preparation–Decision–Design–Assessment (PDDA) process that focuses on quality oriented development, as a cyclical process to develop the architecture. The PDDA was motivated from the practice of architecture-based development used in software engineering fields. In the preparation step of the PDDA, the architecture of digital-based I&C systems was setup for an architectural goal. Single failure criterion and determinism were setup for architectural drivers. In the decision step, defense-in-depth, diversity, redundancy, and independence were determined as architectural tactics to satisfy the single failure criterion, and sequential execution was determined as a tactic to satisfy the determinism. After determining the tactics, the primitive digital-based I&C architecture was determined. In the design step, 17 systems were selected from the KSNP's I&C systems for the upgrade and functionally grouped based on the primitive architecture. The overall architecture was developed to show the deployment of the systems. The detailed architecture of the safety systems was developed by applying a 2-out-of-3 voting logic, and the detailed architecture of the non-safety systems was developed by hot-standby redundancy. While developing the detailed architecture, three ways of signal transmission were determined with proper rationales: hardwire, datalink, and network. In the assessment step, the required network performance, considering the worst-case of data transmission was calculated: the datalink was required by 120 kbps, the safety network by 5 Mbps, and the non-safety network by 60 Mbps. The architecture covered 17 systems out of 22 KSNP's I&C systems. The architecture is implementable with the equipment developed in South Korea. The architecture can be used as a model to upgrade the existing I&C systems in a planned, large-scale, and one-shot manner. A more detailed architecture down to software level will be developed in the future.     

PPS纤维及其在袋式除尘领域的应用

概述PPS纤维的发展状况,介绍了PPS纤维的性能、提高滤袋针刺毡质量的途径及PPS滤料的应用实例。     

共混和复合对聚苯硫醚结晶形态的影响

介绍了聚苯硫醚的结晶特性，讨论了共混或复合的方法对其结晶形态的影响及机理，并对近年来该领域的研究进展进行了简要的评述。