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1.
动态疲劳对未填充天然橡胶硫化胶结构与动态黏弹性的影响 总被引:1,自引:0,他引:1
通过磁共振交联密度仪、衰减全反射傅里叶变换红外光谱仪和动态力学分析仪,对未填充天然橡胶(NR)硫化胶在拉伸疲劳前后结构及动态黏弹性的变化进行了研究.结果表明,未填充NR硫化胶的交联密度随拉伸疲劳时间的延长先增大后减小,拉伸强度和100%定伸应力在拉伸疲劳后期明显下降;未填充NR硫化胶在拉伸疲劳后生成了共轭二烯、三烯类结构,并导致拉伸疲劳后未填充NR硫化胶在高弹区的储能模量大幅度下降.损耗因子则随拉伸疲劳时间的延长明显增高. 相似文献
2.
Cardanol is the main ingredient of cashew nut shell liquid, an agro‐byproduct. Its comparative merits vis‐a‐vis aromatic oil for plasticizing HAF‐black‐filled natural rubber (NR) is the subject of this article. Aromatic oil is the conventional plasticizer employed for such compounding requirements. The mechanical properties, ageing behavior, and torque time curves during cure of NR plasticized by both these materials are compared under identical conditions. It has been established that cardanol, when used as plasticizer, gives rise to similar tensile properties, shorter cure times, and superior ageing behavior compared to aromatic oil. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4835–4841, 2006 相似文献
3.
Recycling discarded rubber is important for both environmental and economic reasons. One of the most attractive methods of recycling rubber waste is to use ground rubber (GR) as a compounding ingredient or as a replacement for raw polymers. In this study, ground natural rubber was prepared with different curing systems and compounded into the parent compounds. The cure behaviors and physical properties of the GR‐filled vulcanizates were investigated, and they were largely affected by the curing systems of the rubber matrix and GR. GR‐filled vulcanizates with GR and the rubber matrix, having a conventional curing system, showed the largest changes in the cure characteristics. The greatest decrease in the physical properties was observed for peroxide‐cured‐GR‐filled vulcanizates. The addition of GR decreased the crosslink density of the GR‐filled vulcanizates. This was thought to be the main reason for the reduction of the mechanical properties of the GR‐filled vulcanizates. However, the adhesion between the GR and rubber matrix may also have caused the differences in the physical properties of the GR‐filled vulcanizates with respect to the curing systems of the rubber matrix and GR. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
4.
Processability and viscoelastic properties of natural rubber (NR) compounds filled with different carbon black loadings and types were investigated with the use of a steady shear rheometer, namely, the Mooney viscometer, and an oscillatory rheometer, namely, the Rubber Process Analyser (RPA2000). It was found that the type and amount of carbon black strongly influence the viscoelastic properties of rubber compounds. Both the dilution effect and filler transient network are responsible for the viscoelastic properties, depending on the vulcanization state. In the case of uncured compounds, the damping factor of the uncured NR decreases with increasing black loading. This is attributed to the reduction of mobilized rubber content in the compound (or the dilution effect). However, in the case of the cured NR vulcanizates, the filler transient network is the dominant factor governing the damping factor of the vulcanizate. With increasing black loading, the damping factor of the vulcanizate clearly increases. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 2197–2203, 2005 相似文献
5.
The submicrostructure of dynamically fatigued unfilled natural rubber vulcanizates was investigated by using scanning electron microscope (SEM) and atomic force microscope (AFM). AFM photographs showed the sample surface roughness became worse after tensile fatigue and the largest surface undulation was as twice that of the unfatigued sample. SEM photographs showed that many micropores of 101–102 nm, a sort of defect, occurred on the cross section of samples after tensile fatigue. The surface roughness became weaker and the size of the micropore was reduced to a few to dozens of nanometers with the addition of antiaging agent N‐(1,3‐dimethyl butyl butyl)‐N′‐phenyl‐p‐phenylene diamine (4020); furthermore, the mechanical properties and dynamic viscoelastic properties in the later period of fatigue changed much. E′ decreased greatly and tan δ increased obviously with the extension of fatigue. It indicated that 4020 was only effective in the early period of tensile fatigue.© 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
6.
Shuguo Chen Yong Zhang Ruyin Wang Haiyang Yu Martin Hoch Sharon Guo 《应用聚合物科学杂志》2009,114(5):3310-3318
The mechanical properties, flame retardancy, hot‐air ageing, and hot‐oil ageing resistance of ethylene‐vinyl acetate rubber (EVM)/hydrogenated nitrile‐butadiene rubber (HNBR)/magnesium hydroxide (MH) composites were studied. With increasing HNBR fraction, elongation at break and tear strength of the EVM/HNBR/MH composites increased, whereas the limited oxygen index and Shore A hardness decreased slightly. Hot‐air ageing resistance and hot‐oil ageing resistance of the composites became better with increasing HNBR fraction. Thermal gravimetric analysis results demonstrated that the presence of MH and low HNBR fraction could improve the thermal stability of the composites. Differential scanning calorimeter revealed that the glass transition temperature (Tg) of the composites shifted toward low temperatures with increasing HNBR fraction, which was also confirmed by dynamic mechanical thermal analysis. Atomic force microscope images showed MH has a small particle size and good dispersion in the composites with high HNBR fraction. The flame retardancy, extremely good hot‐oil ageing, and hot‐air ageing resistance combined with good mechanical properties performance in a wide temperature range (?30°C to 150°C) make the EVM/HNBR/MH composites ideal for cables application. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
7.
Tarek M. Madkour 《应用聚合物科学杂志》2004,92(5):3387-3393
Step‐strain stress relaxation experiments were performed on natural rubber vulcanizates of various carbon black (HAF) concentrations by subjecting the samples to a very rapid strain and fixing its length at the deformed state. Time–temperature superposition in the viscoelastic region was evaluated to investigate the effect of temperature on the relaxation times of the rubbery composites. Remarkably, it was observed that, at higher HAF concentrations, increasing the temperature had a lesser effect on decreasing the overall stress values. That was attributed to the lower number of elastomeric chains per unit volume due to the agglomeration of the carbon black particles. The energy barrier resulting from the adsorption of the rubbery chains on the filler particles was insufficient to drastically reduce the diffusion and rearrangement of the polymer chains. The activation energy of the rubber‐like deformation calculated from the time–temperature superposition was shown to be independent of temperature. Interestingly, the viscosity coefficients showed a large increase with a modest addition of the carbon black. This is due to the long‐range nature of the temporary bonds formed between the polymer molecules and the surface‐active carbon black. The stress–strain of the rubbery composites was shown to behave in a Gaussian manner in accordance with the Mooney–Rivlin relationship. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3387–3393, 2004 相似文献
8.
The concept of double networks is a rather new idea, by which one imparts chain orientation in elastomers. Double networks were made in natural rubber vulcanizates cured with a single and a new binary accelerator system. Double networks with different extensions were prepared and their effects on tensile properties were analyzed. The influence of extent of initial cure on double‐network formation was examined. Thermal stability of the double network formed was analyzed by ageing of the double networks and was found to improve with residual extension. Crosslink density of the networks formed was determined by swelling methods and stress–strain analysis. It was found that crosslink density increased with double‐network formation and residual extension. The stress–strain behavior and moduli were analyzed to study the effect of these properties on double‐network formation. Double networks were hardly affected by the binary accelerator system. Based on the studies it was found that residual extension was the major factor determining the final properties. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1068–1076, 2004 相似文献
9.
Daniele F. Castro Joo Carlos Miguez Suarez Regina C. R. Nunes Leila L. Y. Visconte 《应用聚合物科学杂志》2003,90(8):2156-2162
The rheometric, mechanical, and dynamic mechanical properties as well as fracture surfaces of natural rubber–mica and polybutadiene rubber–mica vulcanizates were studied. Mica was used in the range of 0–30 phr and the rheometric study was carried out at 160°C. The results indicate that the mechanical properties are improved as filler addition increases. Dynamic mechanical testing was used to analyze the observed mechanical behavior. The two elastomers showed different fracture behaviors. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2156–2162, 2003 相似文献
10.
The effects of crosslink structures on the dynamic mechanical properties (DMPs) of unfilled and carbon black N330‐filled natural rubber (NR) vulcanizates cured with conventional (CV), semiefficient (SEV), and efficient (EV) cure systems and having about the same total crosslink densities were investigated before and after aerobic and anaerobic aging at 100°C. The three unfilled NR vulcanizates cured with the CV, SEV, and EV systems had about the same mechanical loss factor (tan δ) values at about 0°C but showed some apparent differences in the tan δ values in the order EV > SEV > CV at relatively high temperatures of 40–80°C before aging. However, N330‐filled NR vulcanizates gave higher tan δ values than the unfilled vulcanizates and showed little effect of the crosslink types on the tan δ at different temperatures over the glass‐transition temperature (Tg) before aging. Aerobic heat aging increased the Tg and tan δ values of the vulcanizates over a wide range of temperatures from ?80 to 90°C that was mainly due to the changes in the total density and types of crosslinks. The unfilled vulcanizates cured with the CV system showed the greatest change in DMP because of their poor resistance to heat aging. Aerobic heat aging of NR vulcanizates caused a more significant change in the DMP than anaerobic heat aging because of the dominant effect of the oxidative degradation during aerobic heat aging on the main‐chain structure, crosslink structures, and DMPs of the vulcanizates. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 710–718, 2001 相似文献
11.
Eiichi Obataya Yuhzo Furuta Yoshitaka Ohno Misato Norimoto Bunichiro Tomita 《应用聚合物科学杂志》2002,83(11):2288-2294
The effects of aging and moisture on the dynamic viscoelastic properties of three oriental lacquer films were investigated. With aging over 1000 days at room temperature, the glass‐transition temperature of the lacquer films (Tα) shifted to higher temperatures, the maximum loss tangent (tanδα) decreased, and the storage modulus at 20°C (E) increased. These changes were analogous irrespective of lacquers. With increasing moisture content, E decreased and tanδ increased at room temperature. Although the equilibrium moisture content of the virgin lacquer (sap) film was higher than that of the clear lacquer film, its E and tanδ were more stable with an increase of moisture content. It was speculated that the polysaccharides aggregated in the sap film did not effectively contribute to the mechanical properties of the film, while their hygroscopicity resulted in higher moisture content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2288–2294, 2002 相似文献
12.
The rubber antioxidant N‐(4‐anilinophenyl) methacrylamide (NAPM) was synthesized by a two‐step reaction using thionyl chloride (SOCl2) with methacrylic acid (MAA) and consequently 4‐aminodiphenylamine (ADPA) as precursors. NAPM was characterized by IR, 1H NMR and elemental analysis. Thermal stability, aging property of NAPM and mechanical properties of natural rubber (NR) vulcanizates containing NAPM were investigated and compared with two other commercial antioxidants N‐isopropyl‐N′‐phenyl‐p‐phenylene diamide (4010NA) and N‐(1, 3‐dimethyl butyl)—N′‐phenyl‐p‐phenylene diamide (4020). It was found that NAPM was an effective antioxidant with a better thermal stability and higher antiaging resistance than unreactive antioxidants 4010NA and 4020. And unsaturation level of NR vulcanizates containing NAPM was lower than that of 4010NA and 4020. Moreover, an antiaging resistant mechanism of a surface reaction between NAPM and cis‐1, 4‐polyisoprene in NR was proposed to explain the better properties of NAPM based on the IR and SEM analyses. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
13.
Acrylic tackifier resins were prepared by free radical polymerization. A natural rubber base was prepared from Standard Malaysian Rubber through mechanical milling. The acrylic tackifier was blended with the rubber base in various ratios. The blends were coated onto strips of paper and tested for shear and peel strengths. Circular samples of the blends were cast onto release paper and their viscoelastic properties studied using DMTA. On plotting storage modulus G′ against frequency, differences between the low frequencies and high frequencies explain the change in pressure‐sensitive adhesive (psa) properties as the percentage of tackifier resin was varied. Blends with good psa have higher loss tangent at higher frequencies. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2118–2123, 2003 相似文献
14.
The effect of the antireversion agent 1,3 bis(citraconimidomethyl)benzene has been studied in a truck compound and a silica containing off‐the‐road compound. Laboratory results show that the antireversion agent significantly improves compound reversion resistance by means of a crosslink compensation mechanism. This improved reversion resistance provides a stabilization of viscoelastic properties on overcure and aging, which in turn should improve the performance of heavy duty tires with regard to rolling resistance and heat buildup throughout their service life. The antireversion agent is particularly effective in stabilizing viscoelastic properties in combination with a reduced level of the saline coupling agent, TESPT. This offers improved tire performance at no cost penalty. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3689–3694, 2002 相似文献
15.
Yijing Nie Bingyin Wang Guangsu Huang Liangliang Qu Peng Zhang Gengsheng Weng Jinrong Wu 《应用聚合物科学杂志》2010,117(6):3441-3447
An investigation of the influence of different types of carbon black on fatigue crack‐growth behavior was undertaken. Fatigue tests were carried out on edge‐notched specimens under cyclic tension loading. A power‐law dependency between the crack‐growth rate and tearing energy was obtained. Natural rubber (NR) filled with N330 (the mean diameter is 30 nm) carbon black possessed the lowest values of exponent b and constant B (the two crack growth parameters determined from cyclic crack growth testing), which denoted the strongest resistance to crack growth at a given tearing energy. Strain‐induced crystallization was investigated by the modified Mooney–Rivlin equation and showed the earliest appearance and strongest ability of the crystallization of the NR/N330 composite at the largest amount of bound rubber. The study on the viscoelastic properties by dynamic mechanical analysis confirmed that the NR/N330 composite had the largest viscoelastic contribution, which was attributed to the viscoelastic dissipation in the viscoelastic region in front of the crack tip. All of these results confirm the best crack‐propagation resistance of NR filled with N330. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
16.
Hsi‐Hsin Shih Po‐Ling Shiao Hsiu‐Chin Hsu Hsin‐Ju Liu Chi‐Jou Huang Chin‐Chin Tsai 《应用聚合物科学杂志》2002,86(14):3695-3701
We characterized metallocene‐catalyzed cyclo‐olefin copolymers (mCOCs) with similar heat distortion temperatures but dramatic differences in melt‐flow indices to understand how the molecular conformation affected their rheological and viscoelastic properties. The mCOC conformations were identified with 13C‐NMR, whereas the viscoelastic and rheological properties were measured with cone‐and‐plate and high‐pressure capillary rheometers. Our preliminary results showed that the mCOC rheological and viscoelastic properties might depend strongly on the conformation rather than the norbornene content, molecular weight, and molecular weight distribution. mCOCs containing ‐NNN‐ locks (where N represents norbornene) exhibited stronger molecular entanglements than those having no ‐NNN‐ blocks, as reflected in lower crossover frequencies and higher crossover torque. Furthermore, the existence of larger rigid ‐NNN‐ blocks resulted in higher molten viscosities and flow activation energies. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3695–3701, 2002 相似文献
17.
The effect of liquid isoprene rubber (LIR) on the dynamic mechanical properties of emulsion‐polymerized styrene/butadiene rubber (ESBR) vulcanizates was investigated by temperature sweep using dynamic mechanical analysis. The introduction of LIR led to ESBR vulcanizates having higher loss factor (tan δ) in the temperature range ? 30 to 0 °C, and lower tan δ in the range 60 to 80 °C. A small amount of LIR‐403 (LIR with carboxyl groups) led to a significant change in tan δ: the addition of LIR‐403 (3 phr) led to a 7.5% increase in tan δ from ? 30 to 0 °C, and a 24.9% decrease in tan δ from 60 to 80 °C. It was found that the introduction of LIR increased the bound rubber content in the ESBR compound. Equilibrium swelling experiments showed that the crosslink density of the vulcanizates increased after the introduction of LIR‐403 or LIR‐50 (general purpose LIR). The change in tan δ from 60 to 80 °C was related to polymer–filler interactions. The characteristic constant of filler–ESBR matrix interaction (m) was calculated. At a given filler volume fraction, the increase in m in the presence of LIR could be well related to the decrease in tan δ from 60 to 80 °C. The influence of LIR on filler network in the ESBR compound was also investigated by strain and temperature sweeps using a rubber processing analyzer. Copyright © 2011 Society of Chemical Industry 相似文献
18.
The effects of crosslinking densities on mechanical properties of nitrile rubber (NBR) composites before and after thermal oxidative aging are investigated. Tensile strengths of NBR composites are enhanced slightly at the initial aging stage, attributing to moderate increment of crosslinking densities. Continuous decrease with further aging is followed, resulting from over-crosslinking and uneven distribution of crosslinking densities. The digital image correlation method is explored for large-strain deformation measurement by displacement accumulation and establishing strain model, being promising in practical age detection and measurement of mechanical properties in complex environments. Compression sets are gradually increased with aging because of the destruction of the original crosslinking structures. The molecular chains fracture inhibits elastic recoveries of compressive NBR composites and results in residual deformation in thermo-oxidative and compressive environment after unloading. This study provides new ideas for exploring mechanical properties of rubber-based composites before and after thermal oxidative aging. 相似文献
19.
20.
Crosslinking of unfilled carboxylated nitrile rubber with different systems: Influence on properties
The presence of two functional groups, nitrile and carboxyl, in carboxylated nitrile rubber allows it to be crosslinked with different agents. In this study, we examined the influence of different crosslinking agents on the properties of unfilled carboxylated nitrile rubber. Significant differences were found when different crosslinking agents were used, as shown in the vulcanization curves, especially in the variation of the viscous component with the reaction time. The reaction rate was highest when organic peroxide was used, and it was lowest when metallic peroxide or copper sulfate was used. When the crosslinking agents led to the formation of ionic bonds (metallic oxide and metallic peroxide), the carboxylic groups ? COOH had a greater participation in the crosslinking. However, when copper sulfate was used, coordination bonds were formed, and the main contribution was due to the nitrile groups. Tensile strength, tear strength, and abrasion properties were superior when the crosslinking systems used led to the formation of ionic bonds. On the contrary, the compression set was optimum when covalent bonds were formed. Copper sulfate behaved as an intermediate between the two previous situations. The mechanodynamic response of the compounds also depended on the crosslinking agent used. The correlation between crosslink density by swelling in dichloromethane, maximum damping temperature by dynamic measurements, and glass‐transition temperature by differential scanning calorimetry had to be explained in terms of the crosslink type. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献