3种微生物脱硫废乳胶及其填充天然橡胶的性能对比

分别利用鞘氨醇单胞菌、脂环酸芽孢杆菌和酵母菌对废乳胶（WLR）进行脱硫再生,考察脱硫过程中微生物的生长情况以及脱硫前后WLR溶胀性和交联密度的变化,并研究WLR和脱硫WLR（DWLR）用量对天然橡胶（NR）拉伸性能和交联密度的影响。结果表明：3种微生物中,鞘氨醇单胞菌脱硫的WLR溶胀指数较大,交联密度较小。随着WLR用量的增大,填充NR硫化胶的拉伸强度和交联密度逐渐减小,拉断伸长率逐渐增大。DWLR/NR硫化胶的拉伸性能明显优于WLR/NR硫化胶,且鞘氨醇单胞菌脱硫的DWLR/NR硫化胶的拉伸性能明显优于其他两种微生物脱硫的硫化胶。     

酵母菌生物脱硫胎面胶粉及其填充天然橡胶的力学性能

用酵母菌对胎面胶粉(GTR)进行了生物脱硫实验,考察了酵母菌与GTR共培养脱硫过程中酵母菌的生长情况,对比了GTR和脱硫GTR(DGTR)填充天然橡胶(NR)硫化胶的交联密度、表面元素含量和力学性能.结果表明,在共培养脱硫过程中酵母菌依然可以保持较高的生物量,脱硫6 d后可获得生物脱硫的GTR.随着胶粉用量的增加,填充NR硫化胶的交联密度和力学性能逐渐降低.相比较GTR/NR硫化胶,DGTR/NR硫化胶的表面硫元素含量和交联密度更低,力学性能明显提高.     

鞘氨醇单胞菌对SBR、NR硫化胶脱硫工艺与效果评估

采用连续与间歇搅拌工艺分别对鞘氨醇单胞菌(PL1)/SBR硫化胶和PL1/NR硫化胶两个体系进行共培养脱硫,系统比较了两种工艺对两种硫化胶片的脱硫效果。结果表明,共培养脱硫过程中,连续与间歇搅拌工艺均可使PL1菌达到较高的生物量;采用间歇搅拌工艺可使更多的PL1在共培养过程中附着在SBR或NR硫化胶片上,提高了菌与硫化胶表面的接触面积;共培养脱硫后,间歇搅拌工艺产生的SBR硫化胶胶片表面S含量比原SBR胶片下降了45.8%,NR硫化胶片表面S含量比原NR胶片下降了32.6%,而采用连续搅拌工艺,脱硫后SBR和NR硫化胶片的S分别为32.8%和11.6%,脱硫SBR胶片表面含氧基团增多;分别采用两种工艺均可使NR胶片主链的C=C遭到破坏;间歇搅拌工艺脱硫胶片的溶胀度比连续搅拌的高,交联密度低。综合效果表明,间歇搅拌工艺在节约能源和提高脱硫效果方面有优势。     

鞘氨醇单胞菌脱硫丁苯橡胶胶粉填充丁苯橡胶性能的研究

利用鞘氨醇单胞菌对丁苯橡胶(SBR)胶粉进行脱硫,对比研究SBR胶粉和脱硫SBR胶粉填充SBR胶料的性能。结果表明:鞘氨醇单胞菌不仅可使硫交联键断裂,也可使橡胶主链上的部分碳-碳双键断裂。与SBR胶粉填充的SBR胶料相比,脱硫SBR胶粉填充SBR胶料的转矩和表观交联密度减小,拉伸强度和拉断伸长率增大,邵尔A型硬度和撕裂强度保持不变,阿克隆磨耗量减小,脱硫SBR胶粉与SBR基体结合较紧密,动态滞后损失较小。     

炭黑N330对NR化学交联的影响

使用硫化扭矩分析、平衡溶胀实验与核磁共振交联密度分析等方法研究了炭黑N330对天然橡胶(NR)化学交联的影响。结果表明,硫化扭矩差值与炭黑用量有较好的线性关系;交联密度变化时,未填充型和已填充型2种硫化胶的溶胀比差和交联密度差均保持不变,说明炭黑N330型对NR的化学交联没有影响。     

核磁共振法表征硫黄用量对天然橡胶交联密度及结构的影响

用核磁共振(NMR)法测定了硫黄用量及硫化温度对天然橡胶(NR)硫化胶交联结构的影响,并与传统的平衡溶胀法进行了对比.结果表明,用NMR法可以测定硫化胶的总交联密度、未硫化胶的物理交联密度和由于交联反应产生的化学交联密度;NR硫化胶的总交联密度和化学交联密度随硫黄用量的增加而呈线性增加;随着硫黄用量的增加.交联密度增加,NR硫化胶的纵向弛豫时间和横向弛豫时间下降;NR硫化胶的交联密度越大,弛豫时间对温度的依赖性越小;NMR法可以清晰展示NR/硫黄/促进剂NS硫化体系的硫化过程中橡胶交联点间的相对分子质量、化学交联密度及橡胶大分子连到橡胶交联网络上的演变过程.     

交联密度对白炭黑/炭黑复合补强NR胎面胶性能的影响

针对卡车胎胎面胶配方,研究了交联密度对白炭黑/炭黑复合填充天然橡胶(NR)胎面胶性能的影响。结果表明,随着促进剂NS、S用量的增加,白炭黑/炭黑复合填充NR混炼胶的硫化速度逐渐加快,焦烧时间ts1、正硫化时间tc90逐渐缩短,硫化胶交联密度明显逐渐提高,导致NR硫化胶300%定伸应力提高,断裂伸长率下降。随着交联密度的提高,DIN及Akron磨耗体积逐渐减小,耐磨性明显提高;NR硫化胶剪切储能模量G′逐渐提高,损耗模量G″的频率依赖性逐渐下降,且二者都随剪切频率增加而提高。损耗因子tanδ在频率扫描及温度扫描下随交联密度增加而减小,与压缩生热结果相一致。     

微生物脱硫胶粉/天然橡胶共混胶的性能

用微生物提取物脱硫改性胶粉(RP),考察了脱硫胶粉(DRP)用量对其与天然橡胶(NR)共混胶的硫化性能、动态力学性能以及物理机械性能的影响,并与RP/NR共混胶进行了对比.结果表明,DRP的加入提高了其与NR的交联程度;DRP/NR混炼胶的Payne效应较RP/NR混炼胶小;随着DRP用量的增加,DRP/NR硫化胶的储能模量降低,损耗因子增大;DRP/NR硫化胶的物理机械性能随着DRP用量的增加而下降,但优于RP/NR硫化胶;DRP在NR中的分散性较RP均匀,与NR的界面结合更强.     

等离子体技术在鞘氨醇单胞菌脱硫废乳胶中的应用

采用等离子体技术对废乳胶进行预处理,利用鞘氨醇单胞菌对其进行脱硫,考察等离子体预处理前后废乳胶亲水性的变化,研究等离子体预处理对废乳胶脱硫效果的影响。结果表明:经等离子体预处理后,废乳胶表面亲水性明显改善;与直接脱硫的废乳胶相比,等离子体预处理后再脱硫的废乳胶表面的砜类基团明显增多,硫质量分数减小,氧质量分数显著增大,硫-氧键含量明显增大,且交联密度明显降低;等离子体预处理能够有效促进废乳胶的微生物脱硫,明显改善脱硫效果。     

硫化胶在高温沥青中结构与性能的研究

采用NR、SBR硫化胶代替废胶粉粉末,在高温沥青(163℃)中进行热存储,测试了不同热存储时间下硫化胶的溶胀指数、交联密度、溶胶含量、硬度、拉伸强度等性能,研究了硫化胶在高温沥青中的结构与性能变化。结果表明,硫化胶在高温沥青中经过一个快速增长而后趋于平缓的溶胀过程;在高温和溶胀作用下,橡胶发生降解,交联密度呈快速下降而后缓慢降低的趋势,溶胶含量随着交联密度的降低显著增加;在溶胀和降解双重作用下,硫化胶硬度、力学性能显著下降。     

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     

Properties of natural rubber vulcanizates containing mechanochemically devulcanized ground tire rubber

The devulcanization of ground tire rubber (GTR) was carried out with a self-designed pan-mill type mechanochemical reactor. Gel fraction and crosslink density measurements confirmed the occurrence of stress induced mechanochemical devulcanization of GTR. The partially devulcanized GTR (dGTR) was blended with virgin natural rubber (NR) at different ratios. The curing characteristics and mechanical properties of these composites were investigated and compared with those composites of raw ground tire rubber (rGTR) and NR. The results showed that the tensile properties of the dGTR/NR vulcanizates were much better than those of the rGTR/NR vulcanizates, which are comparable to or even better than the virgin vulcanizate, indicating the significant benefit of mechanochemical devulcanization. At the GTR content of 10%, the tensile strength of the dGTR/NR blends increased to 23.2 MPa from 13.7 MPa of the rGTR/NR blends, enhanced by 69% through partial devulcanization of GTR, and the elongation at break increased by 47%.     

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     

MG49改性CaCO3对NR硫化胶的结构与性能的影响

用接枝率为49％的天甲橡胶（MG49）改性碳酸钙（CaCO3)。通过混炼胶CaCO3的结合胶质量分数，硫化胶的表观交联密度，界面作用强度，蠕变和力学性能等的测定，研究了改性方法和MG49的用量对CaCO3填充NR硫化胶的结构和性能的影响。结果表明：MG49湿法改性增强了CaCO3与NR间界面的作用强度，改善了CaCO3填充NR硫化胶的网络结构，提高了材料的力学性能。MG49最适宜质量分数为10％。     

Effect of norbornyl modified soybean oil on CB‐filled chloroprene rubber

Carbon black (CB)‐filled chloroprene rubber (CR) compounds and vulcanizates containing naphthenic oil (NO), soybean oil (SO), and two different levels of norbornyl modified soybean oil (MSO) were prepared and investigated. The MSO was prepared through the reaction of SO and dicyclopentadiene (DCPD) at different ratios. Various properties including gel fraction, crosslink density, bound rubber fraction, curing behavior, thermal, mechanical, and aging properties of CB‐filled CR containing different oils were compared. It was observed that the addition of SO and MSO could benefit the dispersion of the filler, lower the glass transition temperature, and increase the thermal stability of the CB‐filled CR/MSO compounds and vulcanizates, and also slightly decrease the crosslink density of the CB‐filled CR/MSO vulcanizates compared to that of the CR/NO vulcanizate. With the increase of the modification level of the MSO, the curing time of the CB‐filled CR/MSO compounds was found to be decreased, the tensile property, tear strength, abrasion resistance, and aging resistance of the CB‐filled CR/MSO vulcanizates were improved compared with those of the CB‐filled CR/NO vulcanizate. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43809.     

Improvement of the properties of natural rubber/ground tire rubber composites through biological desulfurization of GTR

The surface desulfurization of ground tire rubber (GTR) had been carried out via a biological treatment by Thiobacillus sp. with strong sulfur oxidizing capacity. The bonding states and element content on the surface of GTR and desulfurated GTR (DGTR) were evaluated using an X-ray Photoelectron Spectroscopy (XPS). The contact angle of GTR was 120.5° and decreased down to 93.5° after treatment. The cure characteristics, swelling behavior, and crosslink density of natural rubber (NR)/GTR and NR/DGTR were examined. The improvement in mechanical properties was observed for NR/DGTR vulcanizates, which was attributed to the enhanced interfacial interaction between DGTR and NR matrix. The dynamic mechanical analysis (DMA) results showed that NR/DGTR vulcanizates had a reduction of molecular chain friction resistance during glass transition region and Scanning electron microscopy (SEM) studies further indicated a good coherency and homogeneity between DGTR and NR matrix.     

活性预处理三元乙丙橡胶/天然橡胶并用胶的性能

采用硫载体硫化剂4,4′-二硫化二吗啉(DTDM)对三元乙丙橡胶(EPDM)进行活性预处理,研究了活性预处理EPDM/天然橡胶(NR)并用胶的性能,并探讨了活性预处理EPDM对并用胶力学性能影响的机理。结果表明,预处理EPDM/NR并用胶的共硫化程度得到改善,并用硫化胶的力学性能提高;并用硫化胶的耐老化性能优于NR硫化胶,但比未处理EPDM/NR并用硫化胶差;并用胶只存在1个玻璃化温度的转变区,两相的相容性得到改善;在高温动态条件下,EPDM与DTDM发生活性反应,但未生成大量凝胶。     

Preparation of lignin-based filling antioxidant and its application in styrene-butadiene rubber

A novel filling antioxidant (Lig-g-RT) to improve the mechanical properties and antiaging performance of styrene-butadiene rubber (SBR) composites was prepared by grafting antioxidant intermediate p-aminodiphenylamine (RT) on the surface of lignin via the linkage of silane coupling agent. Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) measurements confirmed that RT was successfully grafted on the surface of lignin to produce the functionalized Lig-g-RT which shows a better thermal stability than lignin. Compared with SBR/lignin composite, the SBR/Lig-g-RT composite using latex co-precipitation method exhibits a much better filler dispersion, which contributes to the maintain of the physical mechanical properties of SBR vulcanizates. Moreover, the SBR/Lig-g-RT vulcanizate exhibits less chemical crosslink concentration and higher entanglement density than SBR/lignin vulcanizate according to the Mooney–Rivlin model analysis. In addition, the stabilizing effect of lignin/Lig-g-RT on the carbon-black filled SBR vulcanizates is comparable with that of commercial antioxidant N-1,3-dimethylbutyl-N′-phenyl-p-phenylenediamine (4020), especially the SBR vulcanizate filled with 10 phr Lig-g-RT obtains the optimum thermo-oxidative aging properties. This functionalized Lig-g-RT not only provides an intramolecular synergistic antiaging effect for SBR vulcanizates and an improvement of filler dispersion, but greatly extends the comprehensive utilization of industrial lignin.     

Influence of internal strain on change of crosslink density of natural rubber vulcanizates by thermal ageing

Change of crosslink density of natural rubber (NR) vulcanizates by thermal ageing at 60 °C has been studied under swollen conditions in solvents to investigate the influence of internal strain applied to the vulcanizate on the crosslink density change. The internal strain was controlled by swelling with various solvents such as n‐hexane, toluene, tetrahydrofuran (THF), methanol and water. The order of degree of the swelling is toluene ≈ THF > n‐hexane > methanol > water. The influence of curing system has been investigated with the vulcanizates cured by the conventional and EV cure systems. After thermal ageing, the apparent crosslink densities of the swollen vulcanizates in n‐hexane, toluene and THF decrease irrespective of the cure systems, while that of the swollen vulcanizate in water increases. For the swollen vulcanizates in methanol, the apparent crosslink density of the vulcanizate with the conventional cure system after thermal ageing increases while that of the vulcanizate with the EV cure system decreases. The decrement of the apparent crosslink density of the vulcanizate after thermal ageing becomes larger and larger upon increasing the internal strain. © 2001 Society of Chemical Industry