过氧化物硫化的APA型氟弹性体的耐燃油老化性能

该文主要介绍APA型氟弹性体与传统过氧化物硫化型氟弹性体的长期耐燃油性能比较。选取了标准的含六氟丙烯（HFP）的氟弹性体GF、GF-S、GBL、GBL-S以及含全氟甲基乙烯基醚（PMVE）低温改进型的氟弹性体GLT、GLT-S、GBLT—S、GFLT、GFLT-S进行了5000h的老化试验，老化介质是60℃的CM-15A燃油。在5000h的测试过程中，周期性地测量拉伸强度和体积溶胀的变化数据，此外还进行了燃油渗透测试和在酸性汽油中的性能变化测试，结果发现，APA型具有更佳的耐压缩永久变形性能和良好的耐燃油渗透性能。     

Viton(R)氟弹性体系列专题讲座(九)新型氟弹性体的耐乙醇混合燃油性能及耐渗透性能

在汽车使用的汽油中通常要添加6%～10%的乙醇作为一种常用的控制污染的含氧添加剂.乙醇燃油对橡胶密封件的影响,尤其对氟橡胶的影响,是研究人员关注的焦点之一.该文研究了燃油C和乙醇的混合燃料对几种通常应用于燃油系统的氟弹性体的体积溶胀、拉伸强度、伸长率、渗透率方面的性能影响.     

Viton(R)氟弹性体系列专题讲座(一)加工及使用性能优异的新型过氧化物硫化氟弹性体

基于APA(新型聚合物结构)新型聚合物在2001年及2002年首次合成出来,其分子链结构、分子链封端、硫化交联点都进行了重新设计.文中介绍了几种新型低门尼粘度过氧化物硫化的APA聚合物,以解决那些模压操作困难、性能要求高的密封制品的制造问题.     

Viton氟弹性体系列专题讲座(一) 加工及使用性能优异的新型过氧化物硫化氟弹性体

基于APA(新型聚合物结构)新型聚合物在2001年及2002年首次合成出来,其分子链结构、分子链封端、硫化交联点都进行了重新设计。文中介绍了几种新型低门尼粘度过氧化物硫化的APA聚合物,以解决那些模压操作困难、性能要求高的密封制品的制造问题。     

Viton(R)氟弹性体系列专题讲座(七)新型氟弹性体在石油与天然气工业中的应用(上)

氟弹性体在石油和天然气工业中的应用一直在不断增长之中.由于传统氟弹性体性能的限制,在今天高温高压(HPHT)和苛刻化学介质的环境中,为了满足特定的应用而选择一种适宜的弹性体材料已经愈发困难了.该文主要讨论3种基于APA(新型聚合物结构)技术的氟弹性体,并与传统的FKM和FEPM进行了对比.为了满足高温高压油井中选择最适宜弹性体材料的需要,对室温下和200℃下的物理性能、低温弹性性能、耐化学介质性能,包括在酯类钻井液和甲酸盐中的性能变化进行了对比.同时也讨论了APA聚合物加工性能方面的改善状况.     

Viton(R)氟弹性体系列专题讲座(八)新型氟弹性体在石油与天然气工业中的应用(下)

氟弹性体在石油和天然气工业中的应用一直在不断增长之中.由于传统氟弹性体性能的限制,在今天高温高压(HPHT)和苛刻化学介质的环境中,为了满足特定的应用而选择一种适宜的弹性体材料已经愈发困难了.该文主要讨论3种基于APA(新型聚合物结构)技术的氟弹性体,并与传统的FKM和FEPM进行了对比.为了满足高温高压油井中选择最适宜弹性体材料的需要,对室温下和200℃下的物理性能、低温弹性性能、耐化学介质性能,包括在酯类钻井液和甲酸盐中的性能变化进行了对比.同时也讨论了APA聚合物加工性能方面的改善状况.     

Viton(R)氟弹性体系列专题讲座(三)新型氟弹性体在航空密封领域内的应用进展(上)

半个世纪以来,Viton(R)氟弹性体被成功应用在苛刻的宇航领域中.极端的高温与低温是飞行过程的固有特性.文中讨论的几种过氧化物硫化新型氟弹性体,其工作温度-45℃～+275℃,工作介质为空气、润滑油、标准参比油等.这些新型氟弹性体均采用APA技术合成,经过各种试验后发现,其具有更高的使用性能、更好的加工性能,能满足制造高品质航空密封件的需要.     

Viton(R)氟弹性体系列专题讲座(四)新型氟弹性体在航空密封领域内的应用进展(下)

半个世纪以来,Viton(R)氟弹性体被成功应用在苛刻的宇航领域中.极端的高温与低温是飞行过程的固有特性.文中讨论的几种过氧化物硫化新型氟弹性体,其工作温度-45℃～+275℃,工作介质为空气、润滑油、标准参比油等.这些新型氟弹性体均采用APA技术合成.经过各种试验后发现,其具有更高的使用性能、更好的加工性能,能满足制造高品质航空密封件的需要.     

Viton氟弹性体系列专题讲座(四) 新型氟弹性体在航空密封领域内的应用进展(下)

半个世纪以来,Viton氟弹性体被成功应用在苛刻的宇航领域中。极端的高温与低温是飞行过程的固有特性。文中讨论的几种过氧化物硫化新型氟弹性体,其工作温度-45℃~+275℃,工作介质为空气、润滑油、标准参比油等。这些新型氟弹性体均采用APA技术合成,经过各种试验后发现,其具有更高的使用性能、更好的加工性能,能满足制造高品质航空密封件的需要。     

Viton氟弹性体系列专题讲座(三) 新型氟弹性体在航空密封领域内的应用进展(上)

半个世纪以来,Viton氟弹性体被成功应用在苛刻的宇航领域中。极端的高温与低温是飞行过程的固有特性。文中讨论的几种过氧化物硫化新型氟弹性体,其工作温度-45℃~+275℃,工作介质为空气、润滑油、标准参比油等。这些新型氟弹性体均采用APA技术合成,经过各种试验后发现,其具有更高的使用性能、更好的加工性能,能满足制造高品质航空密封件的需要。     

新型氟弹性体在石油与天然气工业中的应用（上）

氟弹性体在石油和天然气工业中的应用一直在不断增长之中。由于传统氟弹性体性能的限制，在今天高温高压（HPHT）和苛刻化学介质的环境中，为了满足特定的应用而选择一种适宜的弹性体材料已经愈发困难了。该文主要讨论3种基于APA（新型聚合物结构）技术的氟弹性体，并与传统的FKM和FEPM进行了对比。为了满足高温高压油井中选择最适宜弹性体材料的需要，对室温下和200℃下的物理性能、低温弹性性能、耐化学介质性能，包括在酯类钻井液和甲酸盐中的性能变化进行了对比。同时也讨论了APA聚合物加工性能方面的改善状况。     

低温型氟橡胶的长期燃油老化与热老化

由新型聚合物工艺(APA)技术制备的低温FKM聚合物,具有与传统技术生产的FKM相类似的体积溶胀和耐热性能,但其低温屈挠性能更佳,且具有良好的耐压缩永久变形性能。     

Kalrez(R)全氟弹性体系列专题讲座(一)Kalrez(R)全氟弹性体的性能

介绍了Kalrez(R)全氟弹性体常用牌号的物理性能及相互之间的性能比较,重点介绍了Kalrez(R) SpectrumTM 6375、7075的耐介质和压缩永久变形性能.     

Kalrez(R)全氟弹性体系列专题讲座(二)——Kalrez(R)全氟密封件的设计

文中介绍了Kalrez(R)密封件的沟槽设计原则,安装Kalrez(R)全氟O形圈的方法,讨论了压缩永久变形在循环温度下对于密封效果的影响,研究了新型断面结构的密封件在燕尾槽中的使用效果.     

Long term biodegradation in vitro of poly(ether urethane urea): a mechanical property study

The effect of in vitro exposure to enzymatic and aqueous environments on the performance of poly(ether urethane ureas) (PEUUs) was studied. Stabilized and unstabilized PEUU samples were treated with papain, distilled water, or activating agent solutions. Durations of treatments were two weeks and one month. Treated and untreated samples were subjected to tensile and fatigue testing. A significant decrease in fatigue lifetime and ultimate tensile stress was observed in unstabilized PEUUs with two weeks and one month aqueous and enzymic treatments. For samples treated for one month with papain, optical microscopy indicated a change in the microdeformation mechanism of the PEUU elastomer from micronecking to crazing. The addition of stabilizers in the PEUU eliminated the loss in mechanical performance in all aqueous environments but was not effective against enzymatic degradation.     

Long term behaviour of poly(vinyl chloride) products under soil buried and landfill conditions

Abstract

The long term performance of poly(vinyl chloride) (PVC) products has been investigated in laboratory scale landfill simulation assays. Leachate and gas were monitored and PVC samples were inspected. No degradation of the PVC polymer was observed. Plasticised PVC products showed a certain loss of additives. In addition, leachate samples from actual landfill sites were analysed for phthalates and organotin compounds. A preliminary assessment of the environmental impact indicates that there is no significant contribution of PVC waste to concentrations of heavy metals in landfills, and the presence of phthalates and organotin compounds in the leachate is not expected to constitute a risk to the aquatic environment.     

Characterization of the morphological modification induced by long term operations on phosphoric acid fuel cell (PAFC) electrodes

The modification of the morphological and adhesive binding of PAFC electrodes has been studied by electron spectroscopy and electron microscopy with regard to their endurance and preparative treatments. The corrosion of the electrodes has been found to dramatically affect the electrical and adhesive contact between PTFE (polytetrafluoroethylene) and active carbon. This has been detected in X-ray photoelectron spectroscopy (XPS) by the charging shift seen for F 1 s due to the loss in electronic contact between these components. In addition, the adhesive character of the contact between the SiC matrix and the gas diffusion electrodes has been revealed by the XPS spectral characteristics. Here a major difference between the anode and the cathode has been observed with the cathode having a greater deadhesion. Extensive physical characterization by pore volume and size distribution, wetting, and weight loss has been performed. These results have been correlated with the XPS results to give a complete model of the deterioration of this technologically important system. A possible explanation for the observed loss of PTFE from the surface of the cathode based on an electrostatic rejection model of the delaminated PTFE particles is also suggested.     

Metal‐Fluorocarbon‐Pyrolants: III. Development and Application of Magnesium/Teflon/Viton (MTV)

The development and application of pyrotechnic payloads based on magnesium, Teflon^® and Viton^®, so‐called MTV is reviewed. MTV is applied in decoy flares, tracking flares, countermeasure torches, base bleed units, tracer units, igniters, solid rocket propellants, RAM propellants, incendiary devices and signaling applications.     

Metal‐Fluorocarbon‐Pyrolants IV: Thermochemical and Combustion Behaviour of Magnesium/Teflon/Viton (MTV)

The thermochemical and combustion behaviour of pyrotechnic payloads based on magnesium, Teflon^® and Viton^®, so‐called MTV is discussed. Thermochemical and FTIR‐spectroscopic analysis of magnesium/Teflon^® combustion residues indicates the intermediate formation of a Grignard‐type C Mg F compound in the condensed phase as part of a preignition reaction (PIR). The PIR is mainly responsible for the observed burning rate which rises exponentially with rising magnesium weight fractions from ξ(Mg)∼0.2 to ξ(Mg)∼0.70 and declines at ξ(Mg)>∼0.70. A tentative mechanism for the combustion process is presented.     

Phase morphology and surface properties of moisture cured polyurethane-urea (MCPU) coatings: Effect of catalysts

Effect of catalysts on curing behaviour, phase morphology and surface properties of a moisture cured polyurethane-urea (MCPU) coating has been studied. The prepolymer, prepared by capping hydroxy terminated polybutadiene (HTPB) with isophorone diisocyanate (IPDI), was cured with moisture using different urethane catalysts at 30 °C and relative humidity of 60%. Fourier transform infrared spectroscopy (FTIR) was used to monitor the curing process. Gel fraction studies through solubility method, show catalyst induced shortening of induction period for gelation and increase in gel fraction. Effect of catalysts on phase morphology of the MCPU was evaluated by X-ray diffraction, small angle X-ray scattering (SAXS) and differential scanning calorimetry (DSC). The results show that the heat of fusion and interdomain distance of hard segments are influenced by the choice of catalysts. The effect on surface properties was evaluated by FTIR-ATR and contact angle goniometry. The type of H-bonding interaction was identified by deconvolution of the FTIR spectra. The results show that the surface polar group concentrations increase with increasing efficiency of the catalysts. Consequently there is a clear observation of catalyst induced surface energy changes of the MCPU.