Si 69对炭黑增强 NR/BR/NBR共混物性能的影响

研究了双（3-三乙氧基甲硅烷基丙基）四硫化物（Si69）对炭黑增强NR/BR/NBR共混物硫化特性、物理机械性能、滚动阻力以及动态力学行为的影响。结果表明：Si69在炭黑增强体系中抑制硫化,延长了共混物的焦烧、正硫化,减慢了硫化速率。Si69可提高炭黑增强NR/BR/NBR硫化胶的拉伸强度、300%定伸应力、降低滚动阻力,但同时使撕裂强度下降。硫化胶性能的改变主要和Si69的偶联作用有关,Si69改善了炭黑与橡胶间的的相互作用,增加了体系的交联密度,当Si69/炭黑的质量比为8/100时,硫化胶的拉伸强度和300%度伸应力最大,滚动阻力最小。     

Effect of tackifiers on mechanical and dynamic properties of carbon‐black‐filled NR vulcanizates

This work focuses on the effect of tackifiers on mechanical and dynamic properties of carbon‐black‐filled vulcanizates. Three types of tackifiers with difference in softening points are selected for study including petroleum resin, phenolic resin, and gum rosin. The effect of tackifiers on the retardation of vulcanization is observed and the changes in mechanical properties due to the reduction in crosslink density are correlated. Good compatibility between natural rubber and all three tackifiers is verified by a single tan‐delta peak detected for each vulcanizate in temperature ramp test. A similar behavior to the Payne effect which usually found in the case of particulate‐filled rubbers is observed for the tackifier‐filled counterparts. The variation of temperature plays a crucial role in the dynamic behavior of tackified vulcanizates since the state of tackifiers determines its function during dynamic straining. As temperature passed through the softening point of a particular tackifier, substantial reduction in elastic response is observed; however, its relative damping to the untackified may still be maintained. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.     

硫化返原对NR硫化胶结构与性能的影响

研究了硫化返原对NR硫化胶的结构和性能的影响。采用化学探测剂脱硫的方法,测定了硫化返原过程中NR的交联密度和交联键分的变化情况,结果证实了硫化返原的机理;测定了不同温度下随着硫化时间的延长NR力学性能的变化规律以及在硫化期和返原期的动态性能。结果表明,动态生热引起返原,反过来返原导致损耗模量增大,这是轮胎破坏的重要原因。     

Si 69在炭黑填充NR/BR/NBR共混物中的应用

在炭黑填充NR／BR／NBR共混物中加入Si 69，共混物硫化速度降低、物理机械性能提高；Si 69用量为4份时，硫化胶的综合性能最佳。将140℃下用Si 69处理30min后的炭黑加入NR／BR／NBR共混物，可降低硫化胶在65℃下的tan 6值，表明材料的滚动阻力下降。     

Improvement of properties of silica‐filled natural rubber compounds using polychloroprene

Because silica has strong filler–filler interactions, a silica‐filled rubber compound is characterized by a poor dispersion of the filler. Properties of silica‐filled natural rubber (NR) compounds were improved using polychloroprene (chloroprene rubber [CR]). The bound rubber content of the compound increases and the filler dispersion is also improved by adding CR to the compound. Physical properties such as modulus, tensile strength, abrasion, and crack resistance are improved by adding CR. Elongation at break of the vulcanizates containing CR is longer than that of the vulcanizate without CR, although crosslink density of the former is higher than that of the latter. The improved physical properties are attributed to the good dispersion of silica by adding CR. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2609–2616, 2002     

Improvement of the mechanical and thermal properties of silica‐filled polychloroprene vulcanizates prepared from latex system

In this work, well‐dispersed silica suspension having excellent storage stability was prepared by using an ultrasonic probe. The obtained silica suspension and curatives were added into the polychloroprene (CR) latex for preparing silica‐filled CR latex compounds having various silica loadings. Then, the silica‐filled CR vulcanizates were prepared via a dipping process. The thermal and mechanical properties of the dipped CR vulcanizates containing silica dispersed by using an ultrasonic probe were compared with those of the dipped CR vulcanizates containing silica dispersed by using a mechanical stirrer. By using thermogravimetric analysis, it could be seen that thermal resistance of the dipped CR films having silica prepared by ultrasonic probe is greater than that prepared by using the mechanical stirrer. This result corresponds well with their tensile strength after aging in the hot‐air oven. In addition, modulus, tensile strength, and tear strength of the vulcanizates prepared from CR latex compounds containing silica prepared by using the ultrasonic probe are obviously greater than those prepared by using the mechanical stirrer, especially at high silica loading. This is because the silica prepared using the ultrasonic probe is uniformly distributed and dispersed throughout the CR matrix, as can be observed in the scanning electron microscope micrographs. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Continuous ultrasonic devulcanization of carbon black‐filled NR vulcanizates

The continuous ultrasonic devulcanization of natural rubber (NR) filled with various concentrations of carbon black (CB) indicated a minimum of crosslink density and gel fraction at an intermediate amplitude, which is independent of CB content. An attempt was made to improve the efficiency of devulcanization by use of various chemicals (1,3 Diphenylguanidine, 2‐Mercaptobenzothiazole, Thianaphthene). However, these experiments did not indicate any improvement in comparison with devulcanization without chemicals. An idea of adding fresh CB into devulcanized compound, which has been shown to improve mechanical properties in the case of styrene–butadiene rubber (SBR), was tested in the present study for CB filled NR compound. The obtained result indicated that an addition of fresh CB to devulcanized CB‐filled NR did not lead to an improvement in mechanical properties upon revulcanization. The revulcanization recipe was optimized to improve the mechanical properties of revulcanized CB‐filled NR vulcanizates. It was found that CB‐filled NR upon revulcanization retained its strain‐induced cystallizability with the tensile strength and elongation at break at about 50 and 70% level of the virgin vulcanizates. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2340–2348, 2001     

NR/BR/TPI并用胶的性能研究

试验研究NR/BR/反式1,4-聚异戊二烯(TPI)并用胶的性能。结果表明,与NR/BR并用胶相比,NR/BR/TPI并用胶的t90缩短,硫化胶耐屈挠性能得到改善,硫化胶与金属的粘合性能显著提高;动态热力学分析结果说明,TPI用量为10份时,NR/BR/TPI硫化胶具有较大的损耗因子和较低的动态生热(80℃下),可用于橡胶-金属减震制品的开发。     

Influence of mixing procedures and mica addition on properties of NR/BR vulcanizates. I

Elastomeric compositions of natural rubber (NR) and polybutadiene rubber (BR) in a 1 : 1 ratio (w/w), with mica in the range 0–30 phr, were investigated. For all compositions the same formulation was used but two different additives incorporation sequences were followed. The results of the tests showed that the mechanical performance is sequence‐dependent, as the two elastomers have very different rheometric characteristics. It was also observed that mica, when present in amounts of 20 and 30 phr, improves the mechanical properties. Scanning electron microscopy (SEM) permitted the observation of the fracture behavior of each composition, and dynamic mechanical thermal analysis (DMTA) suggested different migration tendencies of the additives in each phase, thus corroborating the differences found for the mechanical properties. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1575–1585, 2004     

Analysis of unbound materials in carbon‐black‐filled NR vulcanizates

Extraction of unbound materials from carbon‐black‐filled natural rubber (NR) vulcanizates with different cure systems was studied using various solvents with different dielectric constants of n‐hexane, toluene, THF, acetone, and acetonitrile. The extraction was performed at room temperature and 40°C for 2 days and in the boiling solvent for 8 h. Amounts of extracted materials from the NR vulcanizates increase by increasing the temperature. Amounts of extracted materials from the NR vulcanizates with n‐hexane, toluene, and THF are more than those with acetone and acetonitrile. Amounts of extracted materials from the NR vulcanizate with a high crosslink density are less than those from the NR vulcanizate with a low one. Thermogravimetric analysis of the NR vulcanizates before and after the extraction were carried out to investigate components of the extracted materials. It was found that there were polymer components and metal complexes, as well as organic matters with a low molecular weight in the extracted materials. Abilities of the solvents to extract unbound materials from the NR vulcanizates were discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1995–2005, 1999     

NR/BR/NBR并用胶的结构与性能

研究了NR／BR／NBR并用胶的结构与性能。透射电子显微镜分析显示，随着NBR用量的增大，炭黑的分散趋于均匀；NR／BR／NBR并用胶出现两个玻璃化温度，在O℃时的tanδ值增幅较大，而在65和80℃时的tanδ值变化不大；并用胶物理性能变化不大。通过调节NBR用量可获得抗湿滑性能较好、滚动阻力和生热小的胎面胶。     

TPI/NR/BR并用胶的性能与应用

研究了不同反式-1,4-聚异戊二烯(TPI)用量及补强与填充体系对TPI/天然橡胶(NR)/顺丁橡胶(BR)并用胶力学性能、动态性能和热老化性能的影响。结果表明,当TPI/NR/BR的质量比为15.0/42.5/42.5时,混炼胶外表光滑,硬度适中;硫化胶的硫化特性变化不大,在保持基本配方硫化胶力学性能的基础上,动态力学性能明显提高。当加入4~8份白炭黑时,并用胶的撕裂强度、定伸应力提高,滚动阻力、压缩生热降低,是一种较理想的全钢子午线轮胎胎侧胶配方。     

偶联剂Si 69对NR/BR/NBR共混硫化胶性能的影响

研究了偶联剂Si 69对NR／BR／NBR共混胶体系的硫化特性、交联密度和硫化胶的物理机械性能及动态力学性能的影响。结果表明，偶联剂Si 69在共混硫化胶中可以起到提高聚合物与填料间的相互作用和交联密度的作用，它在白炭黑增强硫化胶中对性能的改善比在炭黑增强硫化胶中的改善更显著。     

Effect of vulcanization technique on the physical properties of silica‐filled EPDM rubber

The present study aims to enhance EPDM rubber–silica interaction by employing a special technique called Two‐Stage Vulcanization, with the help of a multifunctional rubber additive, bis diisopropyl thiophosphoryl disulfide (DIPDIS). In this process EPDM rubber was heated along with rubber additives up to the time just before the commencement of cure and then filler was incorporated to the preheated rubber to get the final mix. The efficiency of this novel technique is evaluated by the enhancement of physical properties of the silica‐filled vulcanizates. This novel technique is also employed to investigate the effect of a silane‐coupling agent, viz., bis (3‐triethoxy silyl propyl) tetrasulphide (TESPT), in addition to DIPDIS, on the rubber–filler interaction. The positive role of this technique in enhancing the rubber–filler interaction is evidenced by the dynamic mechanical analysis and scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1132–1139, 2006     

Decrosslinking of crosslinked high‐density polyethylene via ultrasonically aided single‐screw extrusion

A novel environmentally friendly process for decrosslinking of the peroxide crosslinked HDPE (XHDPE) via ultrasonic assisted single (SSE) is developed and its process characteristics are established. The specific ultrasonic energy decreases with the flow rate and increases with the ultrasonic amplitude, while die pressure increases with the flow rate and decreases with the ultrasonic amplitude. Application of ultrasonic treatment during extrusion enables an increase of productivity. Gel fraction, crosslink density, dynamic and mechanical properties, and thermal behavior of the virgin HDPE, XHDPE, and decrosslinked XHDPE are measured. Gel fraction and crosslink density of the decrosslinked XHDPE are decreased with increasing flow rate and ultrasonic amplitude. A unique linear relation between the normalized gel fraction and the normalized crosslink density is found, regardless of the type of extruders and processing conditions. SEM images reveals that the decrosslinked XHDPE is a composite of submicron size gel particles embedded in its sol matrix. The sol extracted from the decrosslinked XHDPE exhibits a higher complex viscosity and higher level of branching than the virgin HDPE. An increase of the ultrasonic amplitude leads to a decrease of the complex viscosity, storage and loss moduli, and an increase of the loss tangent of the decrosslinked XHDPE. The thermal behavior and mechanical properties of the decrosslinked XHDPE show a weak dependency on processing conditions. At some processing conditions, mechanical properties of the decrosslinked XHDPE are close or higher to those of XHDPE. POLYM. ENG. SCI., 54:2715–2730, 2014. © 2013 Society of Plastics Engineers     

Effect of nano zinc oxide on the cure characteristics and mechanical properties of the silica‐filled natural rubber/butadiene rubber compounds

With the increasing interest in environmental and health issues, legal restrictions, such as European Union (EU) End of Life Vehicle Directives, were strengthened. This led us to incorporate nano zinc oxide (nano‐ZnO), with particle sizes of 30–40 nm and specific surface areas of 25.0–50.0 m²/g, instead of conventional ZnO into natural rubber (NR)/butadiene rubber (BR) compounds to decrease the content of zinc in the formulation. In the unfilled system, only a 20 wt % nano‐ZnO content, compared to conventional zinc oxide content, showed the cure characteristics and mechanical properties of the same level. This was because the increase in the specific surface area of the nano‐ZnO led to an increase in the degree of crosslinking. The effect of nano‐ZnO on the cure characteristics and mechanical properties was more pronounced in the silica‐filled system than in the unfilled system. This was mainly because of the dispersing agent used in the silica‐filled system, which also improved the dispersion of nano‐ZnO. The silica‐filled NR/BR compounds containing 0.3–3.0 phr of nano‐ZnO showed improved curing characteristics and mechanical properties, such as optimum cure time, 100 and 300% modulus, tensile strength, and tear strength compared to the compound with 5 phr of conventional ZnO. The optimum amounts of nano‐ZnO and stearic acid were only 1.0 and 0.1 phr, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Study on characterization and properties of nanosilica‐filled thermoplastic vulcanizates

Thermoplastic vulcanizates (TPVs) are a special class of thermoplastic elastomer, produced by simultaneously mixing and cross‐linking a rubber with a thermoplastic at elevated temperature. Dicumyl peroxide‐cured TPVs based on blends of maleated ethylene propylene rubber (m‐EPM) and polypropylene (PP) thermoplastic using maleated‐PP as a compatibilizer have been developed. To reinforce the properties of these TPVs, nanosilica was added at different levels. With the increase of nanosilica concentrations, significant improvement in tensile strength, modulus, and impact strength of TPVs have been achieved. Morphology study shows that nanosilica is uniformly dispersed in the polymer matrices. Dynamic mechanical analysis shows that tan δ value at low temperature decreases with increasing nanosilica concentration indicating less damping characteristics. Thermogravimetric study revealed that thermal stability of TPVs is improved in presence of nanosilica. Equilibrium swelling study confirms that solvent resistance of TPVs could be improved by nanofiller incorporation. Rubber process analyzer found a very useful tool to understand the melt rheology of nanosilica filled TPVs in terms of dynamic functions over a wide range of strain amplitude and frequency. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Tribological and electrical properties of silica‐filled epoxy nanocomposites

The tribological and electrical properties of epoxy composites filled with nano‐sized silica particles are studied and discussed in this article. To enhance the interfacial interaction between the fillers and the matrix, nanoparticles were pretreated with silane coupling agent. Dry sliding wear tests were carried out with configuration of composite sample on a rotating steel disc. Electrical measurements such as AC breakdown voltage, at 50 Hz, high voltage‐low current arc resistance and wet tracking resistance were carried out. The results reveal the influence of nanosized silica loading on wear resistance of the epoxy. It is observed that 10 wt% loading of silica is very effective in reducing the wear loss. With further increase of silica filler loading, the nanoparticles agglomerated and resulted in increase of the specific wear rate. The influence of silica particles on the specific wear rate is more pronounced under sliding wear situation. The influence of silica particle loading on epoxy is evident in the results of electrical parameters like dielectric strength, arc resistance and tracking resistance. These parameters showed improvement with filler loading up to 15 wt% and beyond this value of filler loading noticeable deterioration was observed. The effects of electrical stresses in the morphologies of the surfaces of epoxy nanocomposites are discussed. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Influence of rubber composition on migration behaviors of antiozonants in carbon black‐filled rubber vulcanizates composed of NR,SBR, and BR

Migration behaviors of antiozonants in carbon black‐filled rubber vulcanizates with different rubber compositions of natural rubber (NR), styrene–butadiene rubber (SBR), and butadiene rubber (BR) were studied at constant temperatures of 40–100°C and outdoors. Three single rubber‐based vulcanizates, three biblends, and three triblends were used. N‐Phenyl‐N′‐isopropyl‐p‐phenylenediamine (IPPD) and N‐phenyl‐N′‐(1,3‐dimethylbutyl)‐p‐phenylenediamine (HPPD) were employed as antiozonants. Migration rates of the antiozonants became faster with increasing the temperature. The order of the migration rates in the single rubber‐based vulcanizates was BR > NR > SBR. The migration rates in the vulcanizates containing SBR, on the whole, increased with decreasing the SBR content, while those in the vulcanizates containing BR decreased with decreasing the BR content. Difference in the migration behaviors of the antiozonants depending on the rubber composition was explained both by the intermolecular interactions of the antiozonants with the matrix and by interface formed between dissimilar rubbers in the blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 237–242, 2001