EPDM／PP共混型热塑性弹性体的进展

综述了影响ＥＰＤＭ／ＰＰ共混型热塑性弹性体性能，形态结构的各种主要因素，介绍了ＥＰＤＭ／ＰＰ共混型热塑性弹性体的制备，应用及研究动向。     

聚丙烯类共混型热塑性弹性体的研究进展

聚丙烯类共混型热塑性弹性体由于具有原料丰富、价格低、流动性好、易加工等优点,而成为一类发展迅速且应用范围广泛的高分子材料.简要介绍了聚丙烯共混型热塑性弹性体的制备方法,综述了不同种类热塑性弹性体的研究进展和应用领域,并展望了其发展趋势.     

NBR／PFPA热塑性弹性体组成对力学性能的影响

采用动态硫化法制备了ＮＢＲ／ＰＦＰＡ热塑性弹性体（ＴＰＥ），并重点讨论了ＮＢＲ／ＰＦＰＡ质量配比，填料和增塑剂对热塑性弹性体的拉伸强度，扯断伸长率，耐磨性能和硬度等力学性能的影响，结果表明，ＮＢＲ／ＰＦＰＡ质量配比为８５／１５～７０／３０，ＨＡＦ和邻苯二甲酸二丁酯分别为填料和增塑剂时，可获得性能优异的热塑性弹性体。     

无卤阻燃热塑性弹性体的性能及其应用

热塑性弹性体由于兼有塑料和橡胶的特性。被誉为“第三代合成橡胶”，广泛应用于各个领域。在电线电缆方面．热塑性弹性体因具有良好的耐候性、低温柔韧性、尺寸稳定性及设计灵活性而制作成各种精细的产品。目前，市场上销售的无卤阻燃热塑性弹性体多采用三聚氰胺尿氰酸和磷酸酯复合阻燃剂、无机镁铝阻燃剂等制备而成，前者加工性能差，且易发生迁移；而后者以牺牲弹性体的柔韧性为代价。大大限制了其在各个领域的应用。采用膨胀型阻燃剂生产无卤阻燃热塑性弹性体．可在获得优良的阻燃性能的同时。基本保留热塑性弹性体的特塑性，具有广泛的应用领域和良好的市场前景。     

山都平TMTPV热塑性硫化弹性体应用与加工技术

热塑性弹性体是一类具有橡胶的力学性能及使用性能,又可按热塑性塑料进行加工和回收的材料。该材料在塑料和橡胶之间架起一座桥梁。热塑性弹性体硬度介于橡胶和塑料之间(如图1)。1山都平TMTPV热塑性硫化弹性体应用热塑性弹性体是20世纪50年代出现,用量以10%～20%的年增长速度向上递增。热塑性弹性体具有3大特点:     

氢化苯乙烯热塑性弹性体发展展望

氢化苯乙烯类热塑性弹性体是一种重要的热塑性弹性体,在常温下具有橡胶的高弹性,在高温下表现出热塑性树脂的流动性,可以直接加工成型,广泛应用于国民生产的各行各业.文中从国内外弹性体的政策法规和市场需求入手,介绍了国内氢化苯乙烯热塑性弹性体的总体发展状况和未来市场需求,并从氢化苯乙烯热塑性弹性体下游应用产品阐述了氢化苯乙烯热...     

热塑性弹性体注塑特性研究

热塑性弹性体由于具有橡胶的高弹性和树脂的良好加工性能从而越来越广泛的得到了应用,以手机天线模具为例,通过实验探索并揭示工艺条件对聚氨酯和聚烯烃共混物这两种热塑性弹性体注塑特性影响,为热塑性弹性体注射工艺的优化提供借鉴。     

热塑性聚酯弹性体TPEE

热塑性聚酯弹性体ＴＰＥＥ王睦铿（化工部南通合成材料实验厂）一、前言热塑性聚酯弹性体（简称ＴＰＥＥ）和其他热塑性树脂一样，加工性能优良，既可射出成型，又可挤出成型。制品具有橡胶的柔软性、弹性，又有工程塑料的刚性，是优良的工程弹性体。同其他热塑性弹性体相...     

动态硫化NBR/CPE/EVA TPE的力学性能

用动态硫化法制备了共混型的NBR／CPE／EVA热塑性弹性体(TPE)，讨论了橡塑并用比、增塑剂用量和填料类型等对热塑性弹性体力学性能的影响。研究结果表明，当橡塑并用比为5／1～10／3、增塑剂用量为20～30质量份、填料炭黑用量为30质量份时，配合合理的动态硫化工艺条件，可以制得物理力学性能和加工性能优异的共混型的热塑性弹性体。这方面的研究尚未见文献报道。     

500t/a热塑性聚酯弹性体的开发

本文阐述了500t/a热塑性聚酯弹性体(TPEE)的合成与制备工艺及装置建设、推广应用等方面所取得的技术突破和进展。TPEE具有优异的综合性能,采用模塑方法加工成型,可应用于汽车零部件及其它工业元器件生产,具有广泛的市场应用前景。     

Real gas choked flow conditions at low reduced-temperatures

Real gas choked mass flux is calculated for a frictionless stream expanding isentropically until it reaches the speed of sound and without phase changes. The other parameters associated with the choked state are the pressure, density, temperature ratios, and the speed of sound. Departure of the choked mass flux from the ideal gas model is discussed first in absolute terms and then in relative terms, using the Principle of Corresponding States, for gases with boiling points in the low temperature range. Reduced-stagnation pressures are examined up to values of 30 for hydrogen, neon, nitrogen, argon, methane, krypton, xenon, and R-14 and up to 100 for ⁴He. The corresponding reduced-stagnation temperatures go down to 1.4 and in some cases down to 1.2 for nitrogen and argon. Also discussed are the limiting values of stagnation parameters for which no phase change occurs in the choked state. Compared to the ideal gas, the mass flux may almost double and the critical pressure ratio may decrease by an order of magnitude. The relevance of results is discussed qualitatively and quantitatively for Joule-Thomson cryocooling.     

As-cast microstructures and behavior at high temperature of chromium-rich cobalt-based alloys containing hafnium carbides

Hafnium is often used to improve the high temperature oxidation resistance of superalloys but not to form carbides for strengthen them against creep. In this work hafnium was added in cobalt-based alloys for verifying that HfC can be obtained in cobalt-based alloys and for characterizing their behavior at a very temperature. Three Co–25Cr–0.25 and 0.50C alloys containing 3.7 and 7.4 Hf to promote HfC carbides, and four Co–25Cr– 0 to 1C alloys for comparison (all contents in wt.%), were cast and exposed at 1200 °C for 50 h in synthetic air. The HfC carbides formed instead chromium carbides during solidification, in eutectic with matrix and as dispersed compact particles. During the stage at 1200 °C the HfC carbides did not significantly evolve, even near the oxidation front despite oxidation early become very fast and generalized. At the same time the chromium carbides present in the Co–Cr–C alloys totally disappeared in the same conditions. Such HfC-alloys potentially bring efficient and sustainable mechanical strengthening at high temperature, but their hot oxidation resistance must be significantly improved.     

Chitosan-collagen/organomontmorillonite scaffold for bone tissue engineering

A novel composite scaffold based on chitosan-collagen/organomontmo-rillonite (CS-COL/OMMT) was prepared to improve swelling ratio, biodegradation ratio, biomineralization and mechanical properties for use in tissue engineering applications. In order to expend the basal spacing, montmorillonite (MMT) was modified with sodium dodecyl sulfate (SDS) and was characterized by XRD, TGA and FTIR. The results indicated that the anionic surfactants entered into interlayer of MMT and the basal spacing of MMT was expanded to 3.85 nm. The prepared composite scaffolds were characterized by FTIR, XRD and SEM. The swelling ratio, biodegradation ratio and mechanical properties of composite scaffolds were also studied. The results demonstrated that the scaffold decreased swelling ratio, degradation ratio and improved mechanical and biomineralization properties because of OMMT.     

Capacitance based mass metering for cryogenic fluids

This paper describes a method for measuring the mass of cryogenic fluids in on-board rocket propellant tanks or ground storage tanks. Linear approximations to the Clausius-Mossotti relationship serve as the foundation for a capacitance based mass sensor, regardless of fluid density stratification or tank shape. Sensor design considerations are presented along with the experimental results for a capacitance based mass gage tested in liquid nitrogen. This test data is shown to be consistent with theory resulting in a demonstrated mass measurement accuracy of ±0.75% and a deviation from linearity of less than ±0.30% of full scale mass. Theoretical accuracies are also shown to be ±0.73% for hydrogen and ±1.39% for oxygen for a select range of pressures and temperatures.     

Equipment using a “static-analytic” method for solubility measurements in potentially hazardous binary mixtures under cryogenic temperatures

A new apparatus designed to study, at cryogenic temperatures, thermodynamic equilibria of potentially explosive binary systems such as hydrocarbon-oxygen mixtures is described herein. This equipment has an equilibrium cell which was especially designed to minimize hazards while allowing accurate phase equilibrium measurements. Reliability of results, obtained with this equipment has been verified by working on the nitrogen-propane system, for which data are already available in literature, over a large range of compositions and at various temperatures. Four isothermal curves describing liquid phase compositions at 109.98, 113.77, 119.75 and 125.63 K have been determined. Our experimental data are represented within 2% in compositions and in pressures through the Peng-Robinson equation of state implying Mathias-Copeman alpha function and Huron-Vidal mixing rule. Comparisons to literature allow pointing out: good agreement is observed with Kremer and Knapp data (1983) while the three sets of Poon and Lu data (1974) presenting systematic positive deviation are consequently judged as suspicious.     

Gas gap thermal switches using neon or hydrogen and sorption pump

The very low pressure obtained thanks to adsorption phenomenon at low temperature can be used to build cryogenic heat switches, which offer the possibility to make or break thermal contact between two parts of a cryogenic system. The ON (conducting) and OFF (insulating) states of the switch are obtained by varying the gas pressure between two copper blocks separated by a gap of 100 μm. This pressure is controlled by acting upon the temperature of a small sorption pump (activated charcoal) connected to the gap space. For a “high” sorption pump temperature, the gas previously adsorbed in the sorption pump is released to the gap between the two blocks, allowing a good thermal conduction through the gas (ON state). On the opposite, cooling the sorption pump allows a very good vacuum between the copper blocks, which efficiently break the thermal contact (OFF state). Experimental thermal characteristics (Conductance in the ON and OFF state, ON-OFF switching temperature) of such a “Gas Gap Heat Switch” are described using hydrogen or neon as exchange gas and are compared with theoretical calculations.     

Development of No-Vent™ liquid hydrogen storage system for space applications

A number of technological advances required to store and maintain normal-boiling-point and densified cryogenic liquids, including liquid hydrogen, under zero boil-off conditions in-space, for long periods of time, have been developed. These technologies include (1) thermally optimized compact cryogen storage systems that reduce environmental heat leak to the lowest-temperature cryogen, which minimizes cryocooler size and input power, and (2) actively-cooled shields that surround the storage systems and intercept heat leak. The processes and tools used to develop these technologies are discussed. A zero boil-off liquid hydrogen storage system technology demonstrator for validating the actively-cooled shield technology is presented.     

Development of a miniature cryogenic fluid circuit and a cryogenic micropump

This article presents the development of a miniaturized cryogenic fluid circuit for distributed cooling of low-temperature tracking detectors in high-energy physics (HEP). The heart of the circuit is a prototype cryogenic micropump. This volumetric pump is compatible with cooling powers of about 10-100 W, and capable of producing pressure heads of up to around 0.3 MPa. Besides detector and electronics cooling in HEP, potential applications are found in the field of superconductor technology.     

Integrated Resonant Self-Pumped Loop and pulse tube cryocooler for cryogenic cooling distribution

Cooling distribution is a vital technology concerning cryogenic thermal management systems for many future space applications, such as in-space, zero boil-off, long-term propellant storage, cooling infrared sensors at multiple locations or at a distance from the cryocooler, and focal-plane arrays in telescopes. These applications require a cooling distribution technology that is able to efficiently and reliably deliver cooling power (generated by a cryocooler) to remote locations and uniformly distribute it over a large-surface area. On-going efforts by others under this technology development area have not shown any promising results.This paper introduces the concept of using a Resonant Self-Pumped Loop (RSPL) integrated with the proven, highly efficient pulse tube cryocooler. The RSPL and pulse tube cryocooler combination generates cooling power and provides a distributive cooling loop that can be extended long distances, has no moving parts, and is driven by a single linear compressor. The RSPL is fully coupled with the oscillating flow of the pulse tube working fluid and utilizes gas diodes to convert the oscillating flow to one-directional (DC) steady flow that circulates through the cooling loop. The proposed RSPL is extremely simple, lightweight, reliable, and flexible for packaging. There are several requirements for the RSPL to operate efficiently. These requirements will be presented in this paper. Compared to other distributive cooling technologies currently under development, the RSPL technology is unique.     

Helium liquefaction with a commercial 4 K Gifford-McMahon cryocooler

This paper describes helium liquefaction using a commercial cryocooler with 1.5 W cooling power at 4.2 K (Sumitomo model RDK415D with compressor CSW-71D, consuming 6.5 kW electrical power), equipped with heat exchangers for precooling the incoming gas. No additional cooling power of cryoliquids or additional Joule-Thomson stages were utilized. Measurements of the pressure dependence of the liquefaction rate were performed. A maximum value of 83.9 g/h was obtained for 2.25 bar stabilized input pressure. Including the time needed to cool the liquefied helium to 4.2 K at 1 bar after filling the bottle connected to the cold head, and correcting for heat screen influences, this results in a net liquefaction rate of 67.7 g/h. Maintaining a pressure close to 1 bar above the bath during liquefaction, a rate of 55.7 g/h was obtained. The simple design enables many applications of the apparatus.