三种含氟橡胶的性能对比

研究了P457氟橡胶、VPL85540氟醚橡胶、PFR 95HT全氟醚橡胶三种生胶的性能及其混炼胶的硫化特性、低温性能、力学性能、耐热空气老化性能、耐介质性能、压缩永久变形性能等。结果表明,相同配方及工艺下,三种含氟橡胶材料由于生胶分子结构不同,性能上存在较大差异。VPL85540氟醚橡胶低温性能最佳,力学性能最差;PFR 95HT全氟醚橡胶在耐高温老化和耐介质方面表现最佳,低温性能最差。在压缩永久变形方面,低于200℃时P457氟橡胶和VPL85540氟醚橡胶的表现优于PFR 95HT全氟醚橡胶;高于250℃时,PFR 95HT全氟醚橡胶由于大分子优异的耐高温性能,其高温压缩永久变形最低。     

低压变耐高温特种润滑油氟醚橡胶胶料的研制

选取了几种氟醚橡胶或氟橡胶生胶,使用不同硫化体系、填料和硫化工艺,研制出了满足技术指标要求的低压变耐高低温氟醚橡胶胶料,并检测了该胶料在不同老化温度和不同老化时间下耐特种润滑油时的压缩永久变形性能。结果表明,在250℃×24h,压缩率为25%,某型特种润滑油中,该胶料压缩永久变形值较小,仅为26%;压制的橡胶密封圈能够较好地满足使用要求,并且耐油稳定性较好。     

氟醚橡胶长期老化性能研究

本研究对某国产氟醚橡胶在空气、燃油中长期老化后的拉伸强度、拉断伸长率、压缩耐寒系数、压缩永久变形、质量变化、体积变化等性能进行了研究,并与丁腈橡胶进行了对比。试验结果表明,氟醚橡胶具有优异的耐热空气及耐燃油介质老化性能,其拉伸强度、拉断伸长率、压缩永久变形在150℃以下的空气和燃油介质中长期老化后保持稳定;氟醚橡胶在初始低温压缩耐寒性能方面比丁腈橡胶略差,但高温、长时间老化后其压缩耐寒系数优于丁腈橡胶;氟醚橡胶在燃油中的质量和体积变化随温度升高而增加,随时间的延长保持稳定,在质量、体积变化及稳定性方面优于丁腈橡胶胶料。     

辐射乳液聚合羧基型丙烯酸酯橡胶的性能评价

评价了辐射乳液聚合羧基丙烯酸酯橡胶的加工性能、力学性能、耐热空气老化性能、压缩永久变形以及耐油性能,并与国外牌号的丙烯酸酯橡胶进行性能对比。结果表明,辐射法丙烯酸酯橡胶加工性能优异,焦烧时间合适,硫化速度快,相对分子质量大,交联网络完整,其硫化胶力学性能和耐油性能优异;其热空气老化性能和压缩永久变形能与国外品牌丙烯酸酯橡胶媲美。     

FKM/ACM并用胶的结构及性能研究

对采用双酚AF/促进剂BPP硫化体系的氟橡胶(FKM)/丙烯酸酯橡胶(AcM)并用胶的各项性能进行研究.结果表明:以双酚AF/促进剂BPP为硫化体系,FKM和ACM可以实现共硫化,制得的FKM/ACM并用胶物理性能优良,耐热氧、耐紫外光和耐臭氧老化性能以及热稳定性较好,压缩永久变形性能优异}扫描电子显微镜显示FKM和ACM具有较好的相容性.     

氟橡胶新型硫化促进剂2,3,5-三苯基四唑氯化物(TTC)的研究

氟橡胶具有优异的耐高温、耐介质性能,广泛应用于密封制品。但是,氟橡胶也存在几个明显的缺点:压缩永久变形大、低温性能差、高温下机械性能低、加工困难和耐水蒸汽性能不好等。为了改善26—41型氟橡胶(偏二氟乙烯/六氟丙烯共聚物)的压缩永久变形,近年来国内外曾作了不少工作,其中一个重要的方面是改进硫化系统。例如美国Dupont公司生产的低压缩永久变形氟橡胶Viton E 60-C采用的是苄基三苯基氯化膦(BPP)为     

增塑剂对氟醚橡胶性能的影响

研究了耐高温型醚酯混合型增塑剂THIOKOL TP-759对氟醚橡胶硫化特性、力学性能、低温性能和流变性能的影响。结果表明,添加TP-759对氟醚橡胶的硫化有延滞效应;硫化胶的拉伸强度降低、硬度、拉断伸长率和压缩永久变形增加;增塑剂TP-759对氟醚橡胶能够起到增塑作用,适量的增塑剂能够降低脆性温度5℃左右,提高压缩耐寒性能并能改善氟醚橡胶的流动性。     

高性能TPV

介绍近几年国外已商品化的5种高性能热塑性硫化橡胶(TPV),包括硅橡胶TPV(TPSiV)、乙烯-丙烯酸酯橡胶(AEM)TPV(ETPV)、SEBS热塑性弹性体TPV(STPV)、ACM TPV和氟橡胶TPV(FTPV)。TPSiV由硅橡胶与PA或TPU组成,具有较好的耐油性能和耐高温性能,广泛用于工业胶管、密封件和汽车发动机机舱结构件等;ETPV由AEM与热塑性聚酯醚弹性体组成,具有优异的耐油性能和耐高温性能等特点,主要用于汽车部件等领域;STPV由SEBS与聚丙烯组成,具有较高的强度、长期耐油性能和长期弹性回复性能,适用于反复屈挠的动态部件;ACM TPV由ACM与聚酰胺组成,具有高温强度高和长期高温耐油性能优异等特点,主要用于油封、防尘罩等领域;FTPV由氟橡胶(FKM)与氟树脂共混而成,其燃油渗透率低、屈挠性好,主要用作汽车燃油管隔离层。     

两种补强填料对氟醚橡胶性能的影响

设计补强填料（炭黑N990/硫酸钡）用量和并用比不同的9个试验配方,研究炭黑N990/硫酸钡用量和并用比对氟醚橡胶胶料硫化特性、耐低温性能、物理性能、耐热空气老化性能、耐介质性能和压缩永久变形的影响。结果表明：炭黑N990/硫酸钡用量和并用比对氟醚橡胶硫化胶性能影响较大;随着炭黑N990/硫酸钡用量的增大,氟醚橡胶硫化胶的力学性能更好;氟醚橡胶硫化胶的耐低温性能主要由橡胶的分子结构决定,同时含胶率越高,硫化胶的耐低温性能越好;氟醚橡胶硫化胶的耐介质性能与其交联程度有关,当炭黑N990/硫酸钡用量增大时,橡胶与其形成的交联网络更加密集,硫化胶的耐介质性能提高。     

航空发动机常用橡胶的热空气老化研究

利用热空气老化理论研究在航空发动机中主要使用的氟橡胶（牌号FX-17）和氟醚橡胶（牌号FM-1）在高温下的老化寿命。利用阿伦尼乌斯方程拟合压缩永久变形性能变化与老化时间的关系,建立在贮存温度下的老化动力学方程,估测两种橡胶在常温下的贮存寿命。试验结果具有较好的线性关系和相关性。氟醚橡胶在长时间贮存情况的形变保持率优于氟橡胶。     

Effect of copper chelates on U.V. stability of butyl rubber and SBR rubber

An investigation of the photo-oxidative degradation and stabilization of IIR and SBR in the temperature range of 258 to 313°K in air with a monochromatic light of 366 nm in the absence and presence of various concentrations of the different copper chelates has been described. The stabilizer performance in IIR and SBR was accessed by carbonyl index and quantum yield measurements. The changes of IIR and SBR during the irradiation with an ultra-violet light (366 nm) have been conducted by viscometrically and actinometric techniques. Irradiations were conducted on the films at 0, 2, 4, 6, 8, 10, 12 and 14 hours and various parameters were obtained.     

Stress softening in natural rubber vulcanizates. Part V. The anomalous tensile behavior of natural rubber

Stress-strain cycling of natural rubber to high strains produces greater softening than amorphous rubbers, but only if the force on the sample is relaxed below a certain value during the cycle. This phenomenon, attributed to crystallization shows why nonrelaxing tests give a longer fatigue life than relaxing tests.     

1-chlorobutadiene–butadiene rubber. IV. Increasing the hydroxyl group content in the rubber

The hydroxyl group content in 1-chlorobutadiene–butadiene rubber (CB–BR) was increased by the following two methods: (1) heating of the CB–BR latex to hydrolyze the unstable chlorine in CB–BR and (2) introduction of hydroxyl by the Menschutkin-type reaction between 2-dimethylaminoethanol (DMAE) and the chlorine in CB–BR. By heating the latex at 70°C for 12 hr, 55% chlorine was hydrolyzed to result in a marked increase in hydroxyl group content in CB–BR, i.e., at least 55% chlorine is situated in the CB units of the 1,4-configuration. Heat-treated CB–BR was found to contain a small amount of conjugated triene structure by UV spectroscopy, which indicates that elimination of some unstable chlorine as hydrogen chloride occurs during latex heating. By reaction with DMAE, 44% chlorine was converted into hydroxyl in toluene at 27°C. CB–BR compounded with DMAE does not suffer from gelation by milling on an open roll. Thus, by these methods, high molecular weight butadiene rubber having various concentrations of hydroxyl groups is obtained.     

天然橡胶/顺丁橡胶/丁苯橡胶自润滑喷蜡橡胶材料的性能

在天然橡胶(NR)/顺丁橡胶(BR)/丁苯橡胶(SBR)为基体的自润滑喷蜡橡胶材料中加入芥酸酰胺,考察芥酸酰胺作为润滑剂时对NR/BR/SBR自润滑喷蜡橡胶材料的硫化特性、力学性能、门尼黏度、摩擦系数及耐老化性能的影响。结果表明,与未加芥酸酰胺的胶料相比,当芥酸酰胺用量为10份时,胶料转矩减小,焦烧时间和正硫化时间缩短,扯断伸长率从388%增加至523%,拉伸强度降低了21.36%,邵尔A硬度、压缩永久变形分别下降5.56%和8.74%,动、静摩擦系数分别减小23.46%和24.82%,门尼黏度降低20.89%,耐热氧老化性能下降。硫化胶拉伸100%停放5 min后,表面出现明显的白色润滑膜,胶料流动性变好,各组分分散得更均匀,断面更光滑。     

Mixing of rubber and viscoelasticity—III. Viscoelastic characterization of gum rubber

This paper is the third in a series where the author attempts to provide scientific interpretation for mixing of rubber. Each gum rubber exhibits its own characterstic behavior during mixing. In the previous paper, the behavior was identified with viscoelastic properties and failure. This paper describes characterization of gum rubbers based on viscoelastic properties. Methods of describing deformation are discussed with a proposal to use material functions for the present purpose. Non-linear viscoelasticity is discussed with a proposal to use a particular linearization scheme. The conventional characterization methods are discussed concerning the limitations and shortcomings of dilute solution methods and the Mooney index. The linearization scheme is applied as the characterization method most suitable for gum rubbers. A number of examples are given to demonstrate the effectiveness of this characterization method in relating the results to molecular architecture. Finally, the discussion covers processability of gum rubbers and their molecular structure.     

Adhesion studies of tyre cords with rubber. I. Synthesis and characterization of natural rubber graft copolymers

Glycidyl methacrylate and N-vinyl pyrrolidone have been grafted onto natural rubber at 32°C using the simultaneous cobalt-60 irradiation technique. The natural rubber samples were swollen in the monomers for 24 h and thereafter subjected to gamma irradiation. The homopolymers formed in the graft copolymerization reactions and unreacted monomer were removed by solvent extraction using acetone and methanol for glycidyl methacrylate and N-vinyl pyrrolidone monomer, respectively. The influence of total dose and monomer concentration on the graft parameters was investigated. The dependence of the rate of grafting on the monomer concentration was found to be 0.93 and 0.80 for glycidyl methacrylate and N-vinyl pyrrolidone, respectively. DSC and TGA studies of the polymers were undertaken. Grafted copolymers based on glycidyl methacrylate were relatively less thermally stable compared with ungrafted natural rubber.     

Preparation of epoxidized rubber using a reactive processing technique. I. Synthesis and characterization of epoxidized polybutadiene rubber

The epoxidation of high cis‐butadiene rubbers (BR) with monoperoxy phthalic acid was successfully performed in reactive processing equipment of the HAKKE mixer at room temperature. The effects of such reaction conditions as the concentration of peroxy acid and reaction time on the epoxidation level and the efficiency of monoperoxy phthalic acid were investigated. The structure of epoxidized BR was characterized by ¹H NMR and Fourier transform infrared spectrometer. Differential scanning calorimeter analysis revealed that the glass transition temperature of epoxidized BR had a progressive increase with epoxidation level. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2987–2992, 2001     

Ultrasonic devulcanization of rubber vulcanizates. I. Process model

Tire and rubber waste recycling is an important issue facing the rubber industry. In addressing this issue, the present article describes the first attempt to formulate a model and to simulate a novel continuous ultrasonic devulcanization process. The proposed model is based upon a mechanism of rubber network breakup caused by cavitation, which is created by high-intensity ultrasonic waves in the presence of pressure and heat. Dynamics of bubble behavior is described by the Notlingk–Neppiras equation with incorporation of an additional term based upon elastic strain-energy potential. Acoustic pressure arising in the ultrasonic field is related to void formation. Their concentration is calculated based upon nucleation and growth of gas bubbles in crosslinked elastomers under negative driving pressure. The breakup of a three-dimensional network in crosslinked rubbers is combined with flow modeling. The viscosity function required for this modeling is based upon a power-law model which includes temperature, shear rate, and gel fraction dependence. © 1996 John Wiley & Sons, Inc.     

Reclaiming of ground rubber tire by a novel reclaiming agent. I. virgin natural rubber/reclaimed GRT vulcanizates

Mechanochemically devulcanized ground rubber tire (GRT) was (re)vulcanized in compositions with virgin natural rubber (NR). The NR/GRT (re)vulcanizates with GRT content from 20 to 60 wt% have been prepared and studied. Reclaiming of GRT was successfully carried out by tetra methyl thiuram disulfide (TMTD) in presence of spindle oil at around ambient temperature. The cure characteristics and mechanical properties of the virgin NR/reclaim GRT blend were studied. The optimum cure time decreases but scorch time remain unaltered with increasing reclaim rubber content in the blend. Effect of carbon black was studied in NR/RR (80/20) blend. Ageing characteristics of different NR/RR blends were evaluated. Scanning electron microscopy (SEM) studies further indicate the coherency and homogeneity in the NR/RR vulcanizate. The dynamic mechanical properties and swelling behavior of NR/RR blend vulcanizates were examined. The elastic and storage modulus of the NR/RR vulcanizates become improve with increasing reclaim rubber content. Electrical properties of NR/RR vulcanizates were also studied. POLYM. ENG. SCI., 47:1091–1100, 2007. © 2007 Society of Plastics Engineers