NR/TPI并用胶半有效硫化体系的研究

考察了促进剂NS用量、硫黄用量和硫载体DTDM对NR/反式-1,4-聚异戊二烯(TPI)并用胶性能的影响.结果表明,在半有效硫化体系中,硫黄用量1.2～1.4份,促进剂NS用量1.4～1.6份时,NR/TPI(80/20)并用胶可以获得良好的综合性能.NR/TPI中使用DTDM后,硫化速度虽略有降低,但胶料焦烧时间延长,加工安全性提高,硫化胶物理机械性能、疲劳性能、滚动阻力以及耐老化性能均得到改善,这与DTDM在NR中的应用相似.     

正交实验法优化浅色NR/EPDM共混胶配方

研究了白炭黑种类对天然橡胶(NR)/三元乙丙橡胶(EPDM)共混胶硫化特性及力学性能的影响。结果表明,不同种类的白炭黑对NR/EPDM并用胶焦烧时间(tc10)的影响较小,对工艺正硫化时间(tc90)和胶料转矩影响较大;白炭黑种类对并用胶力学性能影响显著,添加1165MP的并用胶综合性能最佳。为进一步改善并用胶性能,采用了正交实验法对浅色NR/EPDM共混胶配方进行优化。     

过氧化物体系中天然橡胶/三元乙丙橡胶并用胶的共硫化

研究了以过氧化二异丙苯(DCP)/助硫化剂为硫化体系分别硫化天然橡胶(NR)/三元乙丙橡胶(EPDM)以及NR/预硫化EPDM并用胶的性能,考察了EPDM混炼胶的硫化特性,对并用硫化胶进行了.差示扫描量热分析.结果表明,NR/EPDM并用胶在使用DCP/助硫化荆硫化体系时具有较好的共硫化性;EPDM经预硫化后可以将配合剂固定其中,并能增加EPDM的硫化活性,提高了与NR并用胶的共硫化性.     

NR/EPDM共混胶的制备与性能研究

主要研究了天然橡胶(NR)与三元乙丙橡胶(EPDM)不同并用比对共混胶硫化性能和综合力学性能的影响,并通过动态力学分析仪(DMA)分析了NR与EPDM的相容性。结果表明,随着EPDM用量的增加,共混胶的拉伸强度、撕裂强度和100%定伸应力先下降后升高,拉断伸长率逐渐减少,硬度逐渐增大,并用EPDM后能明显改善NR的耐臭氧老化性能和耐热空气老化性能;动态力学性能分析表明,NR与EPDM相容性差。当NR/EPDM并用质量比为60/40时共混胶综合性能最佳。     

天然橡胶/三元乙丙橡胶共混相态结构对性能的影响

研究天然橡胶(NR)/三元乙丙橡胶(EPDM)体系并用比与粘度比的变化对其物理性能、耐老化性能及相态结构的影响。结果表明:分别调整NR和EPDM的硫化特性并使之保持一致时,可以改善NR/EPDM并用胶的共硫化性能;NR/EPDM体系粘度比不变,NR含量越大,呈连续相态,并用胶的耐老化性能越差;NR/EPDM体系并用比不变,EPDM粘度越低,容易成为连续相态,并用胶的耐老化性能明显提升。     

硫化体系对NR蠕变性能的影响

研究了硫黄硫化体系(CV、SEV、EV)、硫载体硫化体系(DTDM/S、DTDM/TMTD)、过氧化物硫化体系(DCP、DCP/S)对NR蠕变性能的影响。结果表明,硫黄硫化体系中,半有效硫黄硫化体系(SEV)硫化的NR的抗蠕变性能优于普通硫黄硫化体系(CV)和有效硫黄硫化体系(EV)硫化的NR;硫载体硫化体系中,硫载体与硫黄并用的半有效体系硫化的NR胶料抗蠕变性优于硫载体有效体系硫化的胶料;过氧化物硫化的NR抗蠕变性较差,并用硫黄后抗蠕变性改善;适当提高硫化胶交联密度,可提高其抗蠕变性能;以-Sx-为主的硫化胶蠕变相对要小一些,-C-C-、-S-和-S2-为主的硫化胶蠕变较大。     

硫化剂DTDM对EPDM胶料耐热老化性能的影响

研究了DTDM作为硫化剂 ,在常硫硫化体系、半有效硫化体系有有效硫化体系中 ,对EPEM胶料的硫化特力学性能以及耐热老化性能的影响 ,以及防老剂对EPDM胶料的耐热老化性能的影响。结果表明 ,DTDM使EPDM胶料焦烧期变长 ;DTDM影响EPDM硫化胶的力学性能和耐热老化性能的趋势不同 ,需要根据实际需要 ,选择合适的DTDM用量 ;防老剂的加入没有明显提高耐热老化性能     

优化配方设计提高9.00－20 16PR轮胎的综合性能

通过对9.00-20 16PR轮胎胎冠胶、缓冲层、胎肩胶和胎体帘布层内外层胶的配方优化,提高了轮胎的速度、耐久性能.胎冠胶采用NR/BR(50/50)并用、炭黑N234/N220并用(用量54份);胎肩胶采用NR/BR(90/10)并用、硫化体系为促进剂NOBS、硫化剂DTDM和硫黄;缓冲胶采用全NR,炭黑N330/N660并用(用量44份)、硫化体系为促进剂CZ、不溶性硫黄与硫化剂DTDM;内外层胶采用NR/SBR/BR并用、炭黑N330/N660并用(用量40份)、硫化体系采用促进剂NOBS、DM、硫化剂DTDM和硫黄并用.改进后轮胎的速度性能达到110 km·h-1级运转h,耐久性超过120h.     

氟橡胶/三元乙丙橡胶并用胶的性能

研究了不同并用比(质量比)时氟橡胶(FKM)/三元乙丙橡胶(EPDM)并用胶动态硫化和静态硫化后的低温性能、物理机械性能、耐老化性能和热稳定性,并用扫描电子显微镜表征了并用胶.结果表明,当并用比为30/70时,并用胶有较好的相容性;EPDM可以改善FKM的低温性能;随着EPDM用量的增加,并用胶的拉伸强度及邵尔A硬度降低;动态硫化FKM/EPDM并用胶比静态硫化FKM/EPDM并用胶具有更好的耐老化性能,但老化前前者的拉伸强度稍低于后者;FKM/EPDM并用胶的热稳定性优于纯EPDM;静态硫化FKM/EPDM并用胶中片层现象严重,动态硫化FKM/EPDM并用胶的EPDM包覆在FKM中,但相畴偏大.     

改性EPDM与二烯类橡胶的共硫化

在引发剂存在下用高温密炼机制得了马来酸酐(MA)改性EPDM。红外光谱分析表明,MA与EPDM分子发生化学结合。研究了MA改性EPDM与SPR、NR和NBR共混硫化胶的性能。与未改性EPDM相比,MA改性明显改善了EPDM与二烯类橡胶的共硫化性和共混硫化胶的力学性能。     

硫化体系对EPDM硫化胶力学性能的影响

考察了4,4′-二硫代二吗啉（DTDM）,N,N′-间苯撑双马来酰亚胺（HVA-2）,甲基丙烯酸镁与硫黄和过氧化二异丙苯（DCP）复合硫化体系对三元乙丙橡胶力学性能的影响。结果表明,与纯硫黄硫化胶相比,DTDM/HVA-2/S复合硫化体系的EPDM硫化胶拉断伸长率及压缩永久变形均较小,而拉伸强度、定伸应力和硬度均较大,耐老化性能较好。甲基丙烯酸盐可明显提高硫黄、过氧化物硫化EPDM硫化胶的交联密度、拉伸强度、定伸应力和拉断伸长率。在甲基丙烯酸镁/炭黑/EPDM胶料中添加等量S i69改性白炭黑和石蜡油后,硫化胶各项力学性能都有明显提高,定伸应力和硬度保持较低水平,耐热空气老化性能有所改善。     

Cure characteristics and mechanical properties of hydrogenated natural rubber/natural rubber blends

The cure characteristics and mechanical properties of blends consisting of hydrogenated natural rubber (HNR) and natural rubber (NR) blends were investigated. The HNR/NR blends at 50/50 wt ratio were vulcanized using various cure systems: peroxide vulcanization, conventional vulcanization with peroxide, and efficient vulcanization with peroxide. The HNR/NR vulcanizates cured by the combination of peroxide and sulfur donor (tetramethylthiuram disulfide, TMTD) in the efficient vulcanization with peroxide exhibited the best mechanical properties. It was also found that the hydrogenation level of HNR did not affect the tensile strength of the vulcanizates. The tensile strength of the blends decreased with increasing HNR content because of the higher incompatibility to cause the noncoherency behavior between NR and HNR. However, the HNR/NR vulcanizate at 50/50 wt ratio showed the maximum ultimate elongation corresponding to a co‐continuous morphology as attested to by scanning electron micrographs. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

环氧化天然橡胶共交联改性EPDM/NR共混物的性能

将三元乙丙橡胶(EPDM)与环氧化天然橡胶(ENR)共交联改性后,再与天然橡胶(NR)共混,考察了ENR共交联改性EPDM/NR共混胶的硫化特性、硫化胶的物理机械性能、溶胀指数和耐热空气老化性能,并对该硫化胶进行了差示扫描量热分析。结果表明,EPDM经过ENR共交联改性后与NR共混,ENR共交联改性EPDM/NR共混胶的交联程度明显提高,各相达到了同步交联,硫化胶的综合性能得到了显著改善。     

Ranking of rubber vulcanizates used as seals based on effect of accelerated aging

Technical properties such as hardness, tensile strength, ultimate elongation, and rebound resilience are popular in quality control, but the trend in these properties shows a generalized picture of the structure–property relations. Test specimens were aged in hot air by systematically varying the time and temperature from 24 to 96 h at 70 to 100°C. For an effective comparison the observed values were plotted as a function of time, temperature, and formulations. The data thus obtained were correlated with shelf‐aging in particular cases, and it was observed that aging at 100°C for 24 h could be used for such formulations. A “sulfur donor” system cured nitrile‐butadiene rubber (NBR) vulcanizate and an ethylene‐propylene‐diene (EPDM) vulcanizate showed the best retention of properties. Although the SEM micrograph of the NBR was in agreement with this observation, the EPDM was not. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2500–2510, 2000     

环烷酸钕系顺丁橡胶及其共混物的性能

研究了环烷酸钕系顺丁橡胶(LnBR)及其与天然橡胶(NR)共混物的性能,并与新癸酸钕系顺丁橡胶[LnBR(Q)]进行了对比。结果表明,LnBR硫化胶的物理机械性能、耐磨性能与LnBR(Q)相当,但弹性、拉伸疲劳性和生热性等优于后者。LnBR与NR以50／50(质量比)共混后,降低了生胶分子链的刚性,提高了混炼胶的流动性,改善了加工性能,同时也提高了LnBR／NR硫化胶的物理机械性能、弹性以及干湿滑性能等。LnBR与LnBR／NR共混物的热空气老化性能相当,但劣于LnBR(Q)。     

Naturally occurring halloysite nanotubes for enhanced durability of natural rubber/ethylene propylene diene monomer rubber vulcanizate

A facile approach of using halloysite nanotubes (HNTs) was proposed to address the durability performance demands of natural rubber (NR)/ethylene propylene diene monomer rubber (EPDM) blends and to protect them from the deleterious effects of the service environment including ozone, chemicals, abrasion, and cyclic loading. The introduction of HNTs substantially improved the stability of NR/EPDM when exposed to ozone (over fourfold enhancement with the addition of 5 phr HNTs). Moreover, the HNT-filled NR/EPDM vulcanizates offered approximately 66% reduction in the solvent-mediated swelling in comparison to the unfilled sample. Fatigue life studies showed that the HNT-reinforced NR/EPDM composite could withstand 30% more cycles to failure than the un-reinforced NR/EPDM blend. The effect of various HNT loading on the morphological, mechanical, physical, and rheological properties of nanocomposite vulcanizates based on NR/EPDM was also investigated. The morphological investigations revealed that the introduction of HNT into the NR/EPDM rubber matrix caused a rough morphology in fracture surface and a well-dispersed structure was obtained with the addition of up to 5 phr of HNTs. These findings were further supported by rheological, mechanical, and thermodynamical results.     

Preparation of zinc‐oxide‐free natural rubber nanocomposites using nanostructured magnesium oxide as cure activator

The effect of sol–gel synthesized magnesium oxide (MgO) nanoparticles as cure activator is studied for the first time in the vulcanization of natural rubber (NR) and compared with conventional zinc oxide (ZnO) in terms of cure, mechanical, and thermal properties. The NR vulcanizate with 1 phr (Parts per hundred parts of rubber) nano MgO shows an excellent improvement in the curing characteristics and the value of cure rate index is about 400% greater for NR vulcanizate containing 1 phr nano MgO in comparison to the NR vulcanizate with 5 phr conventional ZnO. Both mechanical and thermal properties of NR vulcanizate are found to be satisfactory in the presence of 1 phr nano MgO as cure activator in comparison to conventional NR vulcanizate. This study shows that only 1 phr nano MgO can successfully replace 5 phr conventional ZnO with better resulting properties in the sulfur vulcanization of NR. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42705.     

Mechanical properties and crosslink density of rare earth‐modified high‐abrasion furnace‐filled powdered natural rubber

High‐abrasion furnace‐filled powdered natural rubber [P(NR/HAF)] has more advantages than traditional HAF‐filled bale NR (NR/HAF) because of its better environmental performance and easier processing quality, but its lower mechanical properties are disadvantageous. To improve the mechanical properties, rare earth‐modified HAF‐filled powdered NR [P(NR/HAF‐Ln)] (Ln = Sm,La,Pr) was prepared by means of coacervation–coprecipitation, using rare earth‐modified HAF as separant and filler. The effect on mechanical properties of P(NR/HAF‐Ln) vulcanizate exerted by the emulsifier/HAF ratio, powdering temperature, Ln/HAF ratio and type of Ln, and HAF content were studied. The results indicated that when optimum formulation, the mechanical properties of P(NR/HAF‐Ln) vulcanizate were better than P(NR/HAF) vulcanizate. In addition, the relationship of the apparent crosslink density and HAF content of P(NR/HAF‐Ln), P(NR/HAF), NR/HAF vulcanizates was also investigated, along with their SEM microphotographs of tensile fracture surface, which indicated that the excellent mechanical properties of P(NR/HAF‐Ln) vulcanizate was attributed to correct amount of Ln that could increase crosslink density and reinforce the interface structure of NR matrix/HAF‐Ln particle. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1755–1762, 2006     

Recycling of EPDM waste. I. Effect of ground EPDM vulcanizate on properties of EPDM rubber

Processing, cure characteristics, and mechanical properties of EPDM rubber containing ground EPDM vulcanizate of known composition were studied. Mooney viscosity increases and Mooney scorch time decreases by the addition of the ground vulcanizate. At higher loadings of the ground rubber, the maximum rheometric torque decreases. On addition of ground waste, stress–strain properties and tear resistance increase, whereas heat buildup marginally increases, resilience marginally decreases, low‐strain modulus remains constant, and abrasion resistance decreases. The interplay between the filler effect of the ground EPDM and the crosslink density changes of the EPDM matrix is believed to be the reason for the variation in mechanical properties. It is believed that sulfur migration occurs from the raw EPDM matrix (R‐EPDM) to the ground waste EPDM (W‐EPDM) particle while accelerator migration occurs from W‐EPDM to R‐EPDM. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3293–3303, 2001     

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