聚四氟乙烯的成型加工技术及国内外研究进展

针对聚四氟乙烯(PTFE)的高熔点温度以及高熔点黏度、加工困难等问题,工业上已开发出类似于粉末冶金的冷压烧结、膏状挤出、膨体法以及预浸渍等加工工艺。综述了目前国内外PTFE加工技术的研究进展,并对PTFE成型方法的机理进行了系统阐述。对PTFE加工技术的可实用性以及工艺优缺点进行了分析和评估,最后对PTFE加工技术的发展方向及其应用前景进行了展望。     

氟化工专利精选

低磨耗含氟聚合物复合物包含含氟聚合物(PTFE或PTFE超细粉等)和添加剂颗粒(氧化铝、二氧化硅或金红石二氧化钛)。制备方法:熔融配混或熔融加工。特征:具有低磨耗率,可用可熔融加工或不可熔融加工的含氟聚合物配制。(CN103703065A)     

瑞士Dynean公司开发专用PTFE

３M’Dyneon氟聚物子公司将和瑞士联邦技术学院（ETH）聚合物技术集团开发出可熔融加工的聚四氟乙烯（PTFE）生产工艺。ETH聚合物技术教授PaulSmith称他的合作伙伴“使这项令人激动的技术迈出了关键的一步”。传统观点以杜邦公司Teflon商标而闻名认为PTFE不能像大多数塑料那样被挤压加工，因为其熔融状态粘度很高，但ETH确认有一狭长粘度范围是可熔融加工的。Smith预计去年可熔融加工的PTFE的销售额在４亿美元。瑞士Dynean公司开发专用PTFE     

可熔融加工的PTFE

一般认为PTFE有独特的化学性、耐热性和表面特性，但它不能熔融加工。其制品的制作只能像金属和陶瓷的加工一样，先将粉末压实，然后再 烧结和机械加工。或者通过柱塞和糊状挤出、悬浮液纺丝、直接等离子聚合等方式加工。     

加工方式对PP/EAA/LDH复合材料性能影响

进行了聚丙烯(PP)、乙烯–丙烯酸共聚物(EAA)及水滑石(LDH)复合材料改性一体化研究,并研究了一次熔融挤出加工法和二次熔融挤出加工法对PP复合材料性能的影响。X射线多晶衍射、透射电子显微镜分析表明:两种加工方法制备的复合材料中EAA均插层和剥离了LDH,改善了LDH在PP基体中分散性,并且一次挤出加工效果优于二次挤出加工效果;热失重分析表明,两种加工方式均提高了复合材料的热稳定性能;静态力学性能测试表明:一次挤出加工制备的复合材料PP1的拉伸强度、拉伸弹性模量和缺口冲击强度均高于二次挤出加工制备的复合材料PP2。实验表明一次熔融挤出加工方法对复合材料中LDH插层和剥离效果以及LDH在PP基体中分散效果优于二次熔融挤出加工。     

分散法聚四氟乙烯的流变性能和形态

分散法聚四氟乙烯(PTFE)具有优异的耐热性、耐化学性和电气特性,广泛应用于电子工业、化学工业等领域。分散法树脂通常利用加入润滑剂以糊状方式挤出成管、带、密封条等制品。本文主要利用 Instron 3211型毛细管流变仪研究了分散法 PTFE 在无润滑剂存在下,在高温挤出时的流变性能,并利用 DSC 方法及扫描电子显微镜研究了挤出物的熔融行为和形态,探讨了 PTFE 在310℃挤出时具有极低的表现粘度行为。     

悬浮聚四氟乙烯树脂的改性

聚四氟乙烯(PTFE)熔融粘度特别高(380℃时为10~(11)泊),不能用简便的熔融加工法进行加工。为拓宽它的应用范围,当 PTFE商品化不久,杜邦公司就着手研制能熔融加工的、性能与 PTFE 类似的新品种氟树脂,20世纪60年代聚全氚乙丙烯(FEP)问世,70年代推出了 Teflon PFA 树脂。这两个品种分别是四氟乙烯与六氟丙烯、四氟乙烯与全氟丙基全氟乙烯基醚的共聚物。少量共聚单体参与四氟乙烯的聚合,得到的共聚物中     

耐热性树脂用挤出机

日本田端机械工业公司为氟树脂(PTFE)、超高分子量聚乙烯等耐热性树脂的成型加工,开发成功 TABATA RE 系列挤出机。氟树脂、超高分子量聚乙烯和其他耐热性树脂的熔融粘度要比一般的热塑性树脂高得多,难以用通常的熔融成型、挤出成型法加工。又因为在氟树脂的熔融加工过程中会产生腐蚀性气体,所以机械装置要求配备特殊的附属设备和使用特殊的材质。TABATA RE 系列挤出机是为使上述树脂能     

中国氟化工产业需提高企业竞争力

2007年国内氟化工产能扩张迅速,AHF和HCFC-22的产能已分别达85万t／a和60万t／a;聚四氟乙烯（PTFE）和可熔融加工氟聚合物产能快速增长;FEP、PVDF、氟弹性体产能都达到5000～10000t／a。聚合后处理的技术水平也有了明显进步,PTFE产品中PTFE树脂和PTFE浓缩分散液的产量增长较快,比重已经达到25％～30％。     

PFA熔融焊接技术

<正> PFA是氟塑料的一种,即四氟乙烯与全氟代烷基乙烯基醚共聚物,它除了与四氟乙烯(PTFE)的使用性能相似以外,还具有可熔融性。聚四氟乙烯(PTFE),被称为塑料王。由于它特殊的分子结构:碳链二侧为负电性极强的氟原子占据,形成高键能的C—F键,这种高能键使得PTFE很难熔融,所以氟塑料的加工不同于普通塑料,只能采     

Selective-combustion purification of bulk carbonaceous solids to produce graphitic nanostructures

We demonstrate the use of simple thermal oxidation processes to purify bulk carbon composites produced from thermosets, which were formulated from precursor compositions containing a melt-processible organometallic Ni catalyst in an excess of carbon source. The as-pyrolyzed carbonaceous solids comprise Ni nanoparticles and interpenetrating amorphous and graphitic carbon domains, where the fraction of crystalline carbon is determined primarily by the carbonization temperature. We exploit the adventitious amorphous carbon phase as a pore-forming agent, which is subsequently removed by selective combustion, exposing the embedded graphitic nanostructures and associated metal catalyst nanoparticles, while still retaining the macroscopic dimensions of the initial thermoset polymeric solid. The pore network formed by removal of the amorphous carbon facilitates the mass transport of gas-phase molecules, such as ammonia, to the internal surfaces of the purified carbon solid. The ability to produce nanostructured graphitic carbons in bulk solid forms using simple processing methods will facilitate their development for applications ranging from electrochemical energy storage to gas sorption/filtration.     

改性聚四氟乙烯摩擦学研究进展

介绍了PTFE及其复合材料摩擦磨损性能的国内外研究进展.详细阐述了改性聚四氟乙烯的摩擦性能的三种方法及其优缺点,指出摩擦学领域改性PTFE的主要方法为填充改性,并总结了PTFE及其复合材料摩擦磨损性能的主要研究方向.     

纳米粒子填充PTFE摩擦副材料的研究进展

综述国内外纳米粒子填充聚四氟乙烯(PTFE)摩擦副材料的研究进展,对纳米粒子填充后的减摩抗磨机理进行探讨,提出“滚珠轴承”、膜润滑和界面束缚作用三个观点,分析该项研究在纳米粒子分散技术和纳米粒子与PTFE基体界面处理上存在的不足,并结合复合材料界面处理机理、PTFE表面粘结机理和纳米粒子分散机理,提出一些新的纳米粒子填充PTFE复合材料界面改性和分散技术的方法。     

无机材料填充改性PTFE复合材料研究进展

综述了聚四氟乙烯（PTFE）无机材料填充改性中纤维填充改性，颗粒填充改性以及复合填充改性三大类的改性研究进展。介绍了不同无机填料对于PTFE复合材料的力学性能以及摩擦学性能的影响，包括摩擦因数、拉伸强度以及材料硬度等，发现铜（Cu）粉、二硫化钼（MoS2）以及玻璃纤维（GF）等无机填料成本较低且对PTFE的力学性能以及摩擦学性能改善较为明显，更能满足实际工程应用。最后，分析了国内外近年来研究中所存在的问题，并提出了解决方向。     

功能化聚四氟乙烯微孔膜的研究进展

功能化PTFE微孔膜兼具PTFE微孔膜的优异特性及功能高分子的特殊性能,选择性透过、催化、传输药物、抗菌、质子交换等特殊功能的聚四氟乙烯（PTFE）微孔膜极具应用潜力。本文综述了PTFE微孔膜的特性,总结了近年来采用辐射接枝、表面沉积、涂覆或共混等方法功能化PTFE微孔膜的最新研究进展及其在化工、医学、服装、电子等领域功能化应用的最新成果,并指出目前存在的问题,对今后的研究提出了展望。     

两款高速铁路桥梁支座滑块的制备及对比研究

介绍超高分子量聚乙烯(UHMWPE)和聚四氟乙烯(PTFE)两款桥梁支座滑块的制备方法,并对滑块的性能进行了研究。结果表明,UHMWPE复合滑块具有比PTFE滑块更加突出的综合力学性能,且其承载能力高,自润滑性能好,耐磨损性能突出,是高速铁路桥梁支座的理想之选。就磨损机理而言,PTFE滑块主要表现为粘着磨损,而UHMWPE复合滑块则主要表现为磨粒磨损。     

A comparative study of characteristics of polytetrafluoroethylene fibers manufactured by various processes

A series of polytetrafluoroethylene (PTFE) fibers were manufactured by three processing methods including extrusion process, split‐sheet process and split‐film process. The influence of processing methods on fiber properties were systematically studied using four PTFE powders with various molecular weights (3.86 × 10⁷, 4.71 × 10⁷, 4.92 × 10⁷ and 5.11 × 10⁷, respectively). Morphology, crystallinity, tensile behavior and friction properties of PTFE fibers were compared by scanning electron micrograph, X‐ray diffraction pattern, strength‐elongation curves and friction coefficients, respectively. The results showed that the in terms of flat filaments, mechanical properties became weak with the increase of molecular weight of PTFE powders at first, but were improved dramatically with further enhancement of molecular weight. In the case of both round filaments and split‐film fibers, fiber properties were improved with growth of molecular weight. Based on characteristics and friction coefficients, potential applications of three types of PTFE samples were analyzed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43553.     

Experimental Study on the Reaction Zone Distribution of Impact‐Induced Reactive Materials

The energy release behaviors of a metal‐fluoropolymer composite impact‐induced reactive material (IRM) under high dynamic impact loading were investigated using a new partition pressure test and the multipoint pressure test. The results indicated that a reverse reaction zone and a subsequent reaction zone were formed along the impact direction as the IRM impacted on an aluminum plate at the velocity of 1050–1450 m s⁻¹. The total energy release increased with the increase of impact velocity and the energy released from the impact reaction of IRM in the reverse reaction zone was only 20–30 % of the total energy. Most energy release occurred in the subsequent reaction zone, which was composed of an impact decomposition reaction zone, a thermal decomposition reaction zone and a combustion reaction zone. Three IRM including Al/PTFE, Mg/PTFE, and Ti/PTFE were tested. The Ti/PTFE was most sensitive to the impact velocity, but exhibited the lowest energy release rate. The energy release from the impact reaction of Mg/PTFE was mainly due to the combustion reaction. The high energy release of Al/PTFE was mainly from deflagration reaction. This work provides experimental methods and data for the formulation and evaluation of IRM in engineering applications.     

UV stabilization route for melt-processible PAN-based carbon fibers

Ultraviolet radiation-based stabilization routes were explored to produce carbon fibers from melt-processible PAN-based copolymers. An acrylonitrile/methyl acrylate (AN/MA) copolymer was melt-spun into fibers that were crosslinked using UV radiation. The fibers could then be stabilized by oxidative heat treatment, and subsequently carbonized. Physical and mechanical testing was performed to determine the degree of stabilization and the properties of the stabilized and carbonized fibers.     

Supported Electrospun Ultrafine Fibrous Poly(tetrafluoroethylene)/ZnO Porous Membranes and their Photocatalytic Applications

Supported photocatalytic poly(tetrafluoroethylene) (PTFE)/ZnO porous membranes were prepared by sintering electrospun PTFE/poly(vinylalcohol)/zinc acetate dehydrate composite membranes. Electrospun PTFE membranes were utilized as supports with excellent chemical stability and high specific surface area, while the photocatalyst‐ZnO particles derived from the thermal decomposition of zinc acetate dehydrate were homogeneously immobilized on the surface of ultrafine PTFE fibers. The PTFE/ZnO membranes could be easily recovered and reused after water treatment. PTFE/ZnO membranes are expected to have a wide range of potential applications in photocatalysis and photocatalysis‐membrane reactors, playing the role of a catalyst as well as a selective barrier against contaminants of interest.