过氧化物DCP与硫黄交联丁苯橡胶体系的 拉伸取向行为对比研究

利用傅里叶转换红外光谱仪,通过红外二色法测定过氧化物DCP交联丁苯橡胶(SBR)体系(DCP/SBR硫化胶)与硫黄交联SBR体系(S/SBR硫化胶)在不同拉伸应变下的取向度,并对两种体系的拉伸取向行为进行对比。结果表明:DCP/SBR和S/SBR硫化胶在拉伸过程中的取向度均随应变的增大而增大;在交联密度相近的情况下,S/SBR硫化胶更容易发生拉伸取向行为,其取向度远大于DCP/SBR硫化胶。通过Mooney-Rivlin模型拟合佐证了红外二色法分析结果的正确性。     

校准曲线法测定SBR硫化胶的交联密度及交联键结构

建立了SBR纯胶和N326炭黑增强（60份）两体系的化学交联密度（Xc)-溶胀因子（fs)校准曲线，并用溶胀法测试了两体系的化学交联密度及交联键结构。结果表明，溶胀法测出的Xc要比Shirley Lee等提出的“每消耗3mol二硫化四甲基秋兰姆（TMTD）分子产生1mol交联键”所预测的数值要低。运用建立的校准曲线测定了不同硫黄用量硫化体系（CV，semi-EV,EV)的交联密度，并用溶胀法测其交联密度及交联键类型，对两结果进行了比较。     

三烷基氯化铵对丁苯橡胶1723拉伸性能及硫化特性的影响

在丁苯橡胶(SBR)胶乳中分别填充VIVATEC 500和NORMAN 346环保芳烃油,制备了SBR 1723-1和SBR 1723-2,考察了三烷基氯化铵(TAC)的用量对SBR 1723-1和SBR 1723-2拉伸性能和硫化特性的影响.结果表明,随着TAC用量的增加,SBR 1723-1和SBR 1723-2的...     

平衡硫化体系硫化天然橡胶的平衡硫化性和化学应力松弛行为

<正>WOlff’‘,”采用双（3-三乙氧基甲硅烷基丙基）-四硫化物（St69）与硫黄组成的平衡硫化体系（EC）,既减少了硫化返原的产生,又保留了传统硫黄硫化体系（CV）的优点,同时克服了因采用有效硫化体系（EV）或半有效硫化体系（SEV）所导致的强度等     

门尼黏度对丁苯橡胶1723拉伸性能及硫化特性的影响

在结合苯乙烯和环保高芳烃油质量分数分别为23.6%和27.3%及24.0%和27.2%的情况下,研究了生胶门尼黏度对两种丁苯橡胶1723拉伸性能和硫化特性的影响。结果表明,随着生胶门尼黏度的增加,两种丁苯橡胶的定伸应力、拉伸强度、扯断伸长率及转矩均呈线性增大趋势,硫化时间延长。生胶门尼黏度每增加1个单位,两种丁苯橡胶的25,30,50 min的300%定伸应力分别增大约0.39 MPa和0.38 MPa、0.22 MPa、0.25 MPa和0.32 MPa,拉伸强度分别提高0.30 MPa和0.27 MPa,扯断伸长率分别增大2.8%和3.6%,最小和最大转矩分别增大0.047 dN·m和0.048 dN·m、0.137 dN·m和0.123 dN·m,硫化时间t_(25)、t_(50)及t_(90)分别延长0.11 min和0.13 min、0.10 min、0.15 min和0.19 min。     

几种硫化丁腈橡胶常温化学应力松弛行为的研究

利用叠合曲线方法研究了三种硫化丁腈橡胶分别在空气，８＃润滑油，１０＃和１２＃液压中油中的常温化学应力松弛行为，叠合曲线是根据６０－１００℃下的试验数据构成的，其转换因子按作者提出的公式计算，常温叠合曲线的前一段已为２０年以实际自然老化数据所验证。叠合曲线表明，常温化学应力松驰是一个非常缓慢的过程。     

结合苯乙烯质量分数对丁苯橡胶1723拉伸性能及硫化特性的影响

以2种门尼黏度为49的丁苯橡胶(SBR)1723(环烷油质量分数为27.2%的SBR-1和环烷油质量分数为28.1%的SBR-2)为研究对象,考察了SBR 1723的结合苯乙烯含量对其25 min 300%定伸应力(M_(25))、35 min 300%定伸应力(M_(35))、50 min 300%定伸应力(M_(50))、拉伸强度、扯断伸长率、最小转矩(M_L)、最大转矩(M_H)及硫化时间的影响。结果表明,随着结合苯乙烯质量分数升高,SBR 1723的M_(25)、M_(35)、M_(50)及拉伸强度均线性升高,扯断伸长率线性下降,M_L及M_H均下降,硫化时间延长。结合苯乙烯质量分数每升高1%,SBR-1和SBR-2的M_(25)、M_(35)、M_(50)分别增加0.038 MPa和0.033 MPa、0.026 MPa和0.023 MPa、0.023 MPa和0.032 MPa,拉伸强度增加0.066 MPa和0.068 MPa,扯断伸长率下降0.72%和0.68%,M_L下降0.008 dN·m和0.009 dN·m,M_H下降0.029 dN·m和0.026 dN·m。     

不同温度下杜仲胶/天然橡胶共混硫化胶的拉伸性能及应力松弛

将杜仲胶(EUG)与天然橡胶(NR)进行共混硫化,考察了不同EUG含量以及温度对硫化胶的拉伸性能和应力松弛的影响。结果表明,室温下EUG质量分数超过20%会形成结晶,随EUG质量分数逐渐增加到50%,硫化胶的断裂伸长率和拉伸强度均有不同程度下降;随温度升高,EUG晶区熔融,硫化胶抵抗形变能力降低,形变能力增强。在较高温度下,随EUG含量增加,硫化胶应力松弛的初始模量以及松弛到平衡值时的模量增大;随温度升高,应力松弛的初始模量以及松弛到平衡值时的模量减小。应用分数阶导数Kelvin模型对应力松弛曲线进行拟合,发现随温度升高,硫化胶体系中弹性部分减少而黏性部分增加,松弛时间缩短。     

交联网络状态对CR硫化胶应力松弛的影响

研究了交联网络状态对氯丁橡胶(CR)硫化胶拉伸应力松弛的影响。结果表明,在不同应变速率和相同应变条件下,CR硫化胶瞬时网络状态不同;拉伸过程中,CR硫化胶应变速率越快,其拉伸应力变化率拐点出现越早;当应变为150%时,应变速率越快,应力松弛过程中交联网络粘性越大,可松弛分量越大;在承受外力时,交联网络接近分子链断裂极限状态,不可松弛分量接近;当应变为100%时,应变速率越快,拉伸应力松弛起始阶段参与抵抗外力的化学交联网络越接近极限值,不可松弛分量越大;当应变速率一定时,不同应变下抵抗外力的网络及网络参与度不同,松弛曲线随应变的增大向较大应力方向移动并呈现“准线性”粘弹行为。     

The influence of stabilizers on mechanochemical processes in SBR rubbers

Mechanochemical processes in commercial and model SBR rubbers containing different stabilizers were investigated. The influence of chemical structure and concentration of stabilizers in the temperature range from 20–170°C and in the presence of air, i.e., under conditions similar to that in industrial processes, were studied. Stabilizers used were diaryl‐p‐phenylene‐diamine, alkyl‐aryl‐p‐phenylene diamine, polynuclear phenol, aryl‐alkyl phenol, and alkyl‐alkyl phenol. It was found that mechanochemical processes in SBR rubbers are less developed in the temperature region from 70–130°C, so the influence of stabilizer is less expressive. During increasing temperature (130–170°C) structure and concentration of stabilizers both show a strong influence on type and intensity of mechanochemical processes in SBR rubbers: p‐phenylene‐diamines favor processes of linear degradation, while phenol stabilizers direct them toward branching and crosslinking, which is more expressed in the presence of aryl‐substituted phenols than alkyl‐substituted phenols. This fact is based on the differences in stability of free stable radicals of p‐phenylene‐diamines, alkyl‐substituted phenols and aryl‐substituted phenols. The fact that phenol stabilizers are involved in chain degradation as well as in branching and crosslinking processes during rubber processing, can be of high practical importance. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 835–847, 1999     

Comparative analysis of ultrasonically devulcanized unfilled SBR,NR, and EPDM rubbers

The comparative study of the continuous ultrasonic devulcanization of various unfilled rubbers [natural rubber, styrene–butadiene rubber (SBR), ethylene–propylene–diene rubber (EPDM)] is carried out by means of a ultrasonic reactor. The power consumption, gel fraction, crosslink density, cure behavior, and physical properties of devulcanized rubbers were measured. The glass transition temperatures of virgin, vulcanized, and devulcanized rubbers were determined in order to characterize the difference in the mobility of rubber molecules for each rubber before and after devulcanization. Thermogravimetric analysis was also used to determine thermal stability of the various rubbers. A unique correlation between gel fraction and crosslink density indicated significant differences in the efficiency of devulcanization of various rubbers. Under certain devulcanization conditions, the mechanical properties of revulcanized SBR and EPDM rubbers were found to improve compared to those of the original rubbers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 434–441, 2003     

Tensile stress relaxation of short‐coir‐fiber‐reinforced natural rubber composites

The stress relaxation behavior of natural rubber (NR) and its composites reinforced with short coir fibers under tension was analyzed. The rate of stress relaxation was a measure of the increase in the entropy of the compounds: the higher the rate was, the greater the entropy was. At lower strain levels, the relaxation mechanism of NR was independent of strain level. However, the rate of relaxation increased with the strain level. Also, the strain level influenced the rate of stress relaxation considerably in the coir‐reinforced NR composites. However, the relaxation mechanisms of both the unfilled compound and the composite were influenced by the strain rate. The rate of relaxation was influenced by fiber loading and fiber orientation. From the rate of stress relaxation, we found that fiber–rubber adhesion was best in the composite containing fibers subjected to a chemical treatment with alkali, toluene diisocyanate, and NR solutions along with a hexaresorcinol system as a bonding agent. In this study, the stress relaxation curves could not be viewed as segments with varying slopes; however, a multitude of inflection points were observed on the curves. Hence, we propose neither a two‐step nor three‐step mechanism for the coir‐fiber‐reinforced NR composites as reported for some other systems. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 96–104, 2004     

交联SBR改性沥青的研究

研究了SBR用量和交联对SBR改性沥青的性能与结构的影响。结果表明 ,随着SBR用量的增大 ,改性沥青高温时的粘度、软化点和弹性恢复率均增大 ;SBR经交联后 ,SBR改性沥青的软化点、弹性恢复率和粘韧性均增大 ;SBR改性沥青低温时的延度接近SBS改性沥青的水平 ;交联后虽使改性沥青高温时的粘度增大 ,但不会对施工造成困难 ;化学交联并不影响SBR在沥青中的分散 ,不会使SBR在沥青中聚结。     

氧化亚铁硫杆菌脱硫胎面胶粉/丁苯橡胶并用胶的性能研究

采用氧化亚铁硫杆菌对胎面胶粉(GTR)进行脱硫再生,将生物脱硫胎面胶粉(DGTR)与丁苯橡胶(SBR)共混制备DGTR/SBR并用胶,并对其性能进行研究。结果表明:从氧化亚铁硫杆菌与GTR共培养脱硫再生过程发现,氧化亚铁硫杆菌可以代谢硫化胶粉中的化合硫,脱硫后胶粉的溶胶质量分数增大;与GTR/SBR并用胶相比,DGTR/SBR并用胶的交联密度较小,物理性能显著提高;DGTR/SBR并用胶分子间的摩擦阻力减小,玻璃化温度降低;与GTR相比,DGTR与SBR的界面结合更好。     

Effect of crosslink structures on dynamic mechanical properties of natural rubber vulcanizates under different aging conditions

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 (T_g) before aging. Aerobic heat aging increased the T_g 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     

Tensile fatigue,stress relaxation,and creep behaviors of worsted core spun yarns

The objective of this research was to investigate the time‐dependent behaviors of yarns, which have significant bearings upon the properties of stretch fabrics made from them. In this study, 100% wool, wool–lycra (W‐L) (97 : 3), and polyester–wool–lycra (P‐W‐L) (52 : 45 : 3) blended yarns were considered. These yarns were subjected to the tensile fatigue failure, stress relaxation, and creep experiments. The findings showed that of these three yarns, P‐W‐L blend exhibited maximum fatigue lifetime, stress retention, and creep recovery, the pure wool yarn followed suit albeit to a lesser extent, whereas the W‐L blend made it least. The investigation suggests that wool alone with lycra as a core component is not sufficient to impart the expected properties upon stretch fabrics, rather a blend of polyester and wool with lycra as in the former would definitely make a worthwhile product. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Influence of rubber composition on change of crosslink density of rubber vulcanizates with EV cure system by thermal aging

Variation of the crosslink density of a rubber vulcanizate depending on the rubber composition after the thermal aging was studied with single rubber, biblend, and triblend vulcanizates of natural rubber (NR), butadiene rubber (BR), and styrene‐butadiene rubber (SBR). The efficient vulcanization (EV) system was employed to minimize the influence of free sulfur in the vulcanizate on the change of the crosslink density. Thermal aging was performed at 40, 60, and 80°C for 20 days with 5‐day intervals. The crosslink densities of the vulcanizates after the thermal aging increase. For the single rubber vulcanizates, variation of the crosslink density by the thermal aging has the order: SBR > BR > NR. For the biblend vulcanizates, variations of the crosslink densities of the NR/SBR and SBR/BR blends are larger than that of NR/BR blend. Variation of the crosslink density of the vulcanizate increases by increasing the SBR content in the vulcanizate. Variation of the crosslink density of the rubber vulcanizate depending on the rubber composition was explained by miscibility of the blends, combination reaction of the pendent groups, and mobility of the pendent group. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1378–1384, 2000     

Nonlinear stress relaxation of filled rubber compounds: A new theoretical model and experimental investigation

A new nonlinear hyper-viscoelastic constitutive model was developed to describe the mechanical behavior of filled rubbers. It consists of a conventional strain energy density function like Arruda-Boyce weighted by a four-parameter decay relationship, designed as a function of time and the deviatoric part of the first invariant of the left Cauchy-Green deformation tensor. It was implemented in Abaqus code as a user subroutine. A SBR/BR rubber compound filled with carbon black was selected as the test material. The material parameters were determined by calibrating the data from the uniaxial stress–strain tensile, volumetric, and stress relaxation tests using an optimization loop designed in Isight program. To validate the proposed model, a series of simulations were performed on two rubber strips and a rubber cylinder under extensive and compressive loads, respectively. Comparison with their corresponding experimental data confirmed the accuracy, and validity of the proposed model and approach.     

Influence of external stress on the barrier properties of rubbers

The effect of an external stress on the barrier properties of natural, bromobutyl, and nitrile rubber were studied using a modified ASTM permeation method. Stress‐induced changes such as a decrease in the breakthrough time with mechanical elongation was observed. Upon application of a small mechanical deformation, little change was observed in terms of steady‐state permeation flux. On the other hand, a stress‐enhanced diffusion was observed for most of the solvent/rubber pairs studied. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1584–1595, 1999