单螺杆挤出机连续脱硫制备再生胶的结构与性能

利用本课题组研制的单螺杆挤出机,对废旧轮胎胶(GTR)粉进行连续脱硫制备再生胶(DGTR),并对DGTR进行再硫化制成DGTR硫化试样.结果显示,随螺杆转速增加,DGTR凝胶含量和DGTR硫化试样交联密度逐渐降低,DGTR硫化试样的拉伸强度和拉断伸长率有所提高;螺杆转速设定为40 r·min^-1时,在205℃脱硫温度下取得了最好的脱硫效果,DGTR硫化试样的拉伸强度和拉断伸长率分别约为11 MPa和386%.从红外光谱和光电子能谱的分析结果推测,在单螺杆挤出机的剪切和热等的共同作用下,GTR粉中部分S-S键和C-S键发生了断裂.     

亚临界流体挤出法复合诱导SBR基轮胎胶脱硫化及 再硫化材料力学性能

在SBR基轮胎胶(GTR)与三元乙丙橡胶（EPDM）混合物的熔融挤出过程中,采用改变亚临界流体品种和提高螺杆转速的方法,研究了亚临界流体（水,乙醇,丙醇）、螺杆转速、烷基酚多硫化物促进剂（450）以及温度对脱硫共混物（DGTR/EPDM）凝胶含量、门尼粘度、溶胶红外光谱及脱硫共混物共混丁苯橡胶（SBR）再硫化材料（SBR/(DGTR/EPDM)）力学性能的影响,对再硫化材料的试样断面形貌也进行了SEM观察。实验结果表明：亚临界流体（水,乙醇,丙醇）作为一种溶胀剂和反应性介质能够很好地促进脱硫反应,提高交联键断裂的选择性,降低脱硫产物的凝胶含量和凝胶颗粒尺寸并明显提高脱硫共混物共混丁苯橡胶再硫化材料的力学性能,其中亚临界乙醇的作用最显著。当450作为一种脱硫促进剂,在最优亚临界乙醇挤出反应条件（200℃,1.6 MPa,600 rpm）下,脱硫共混物共混丁苯橡胶分别达到丁苯生胶混炼硫化材料拉伸强度（24.0MPa）和断裂伸长率（356%）的99.6%和209%。     

Effects of shear stress and subcritical water on devulcanization of styrene–butadiene rubber based ground tire rubber in a twin‐screw extruder

The devulcanization reaction of styrene–butadiene rubber (SBR) based ground tire rubber (GTR) in GTR/ethylene–propylene–diene monomer rubber (EPDM) blend was investigated through a compound‐induced reaction by increasing screw rotation speed and being in the presence of subcritical water. The effects of temperature, pressure, screw rotation speed, or promoting agents on the gel content, Mooney viscosity, and Fourier transform infrared spectra of the sol of the devulcanized blends (devulcanized ground tire rubber (DGTR)/EPDM) were measured, and the mechanical properties and microstructures of the revulcanized blend ((DGTR/EPDM)/SBR) were characterized. The results show that subcritical water as a swelling agent and reaction medium promotes the devulcanization reaction, increases the selectivity of the crosslink breakage, keeps the extrusion material from oxidative degradation, reduces the gel particle size of the devulcanized blends, and significantly improves the mechanical properties of the revulcanized SBR/(DGTR/EPDM) blends. In subcritical water, the suitable promoting agents (alkylphenol polysulfide 450, hydrogen peroxide H₂O₂, or 450/H₂O₂) accelerate the devulcanization reaction, keep the double bond content, and lead to further decrease of the gel content and Mooney viscosity of the devulcanized blends and further increase of the mechanical properties of the revulcanized SBR/(DGTR/EPDM) blends. Especially the compound promoting agent (450/H₂O₂) improves the selectivity of the crosslink breakage in devulcanization of SBR‐based GTR. When 450/H₂O₂ is added as a compound promoting agent at the best reaction condition in subcritical water (200°C, 1.6 MPa and 1000 rpm), the tensile strength and elongation at break of the revulcanized SBR/(DGTR/EPDM) blends reach to 85.4% and 201% of vulcanized SBR (24.0 MPa, 356%), respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1845–1854, 2013     

Recycling of tire‐curing bladder by ultrasonic devulcanization

The recycling of butyl rubber‐based tire‐curing bladder was carried out by means of a grooved barrel ultrasonic extruder. Die pressure and ultrasonic power consumption were measured as a function of flow rate and ultrasonic amplitude. Gel fraction and crosslink density of the ultrasonically devulcanized rubber were substantially reduced. In turn, this led to some reduction in gel fraction and crosslink density in the revulcanized rubber. These findings were correlated with dynamic properties and the cure behavior of the devulcanized rubber. The mechanical properties of the revulcanized rubber, dependent on processing conditions during devulcanization, were compared with that of the virgin vulcanizate. Good mechanical properties of revulcanized rubber was achieved with 86 and 71% retention of the tensile strength and the elongation at break respectively, and with modulus increased by 44%. The devulcanized rubber was found to contain tiny gel particles of a wide size distribution with a predominant size of <4 μm. POLYM. ENG. SCI., 46:8–18, 2006. © 2005 Society of Plastics Engineers     

超声波振幅对轮胎胶粉超声脱硫工艺及性能的影响

以40目废旧轮胎胶粉为原料,采用超声脱硫工艺,使用超声同向旋转双螺杆挤出机制备了脱硫废旧轮胎胶粉（DGTR）,研究了超声波振幅对脱硫工艺过程中口型压力和功率消耗,DGTR的外观形貌、流变性能和硫化特性,以及DGTR硫化胶力学性能的影响。结果表明,随着超声波振幅的增加,DGTR的凝胶含量、黏度及储能模量逐渐降低,损耗因子逐渐增大;当超声波振幅为13 μm时,超声DGTR中交联键断裂数量最多,由此表明此时DGTR的脱硫程度最高。此外,随着超声波振幅的增加,DGTR硫化胶的拉伸强度逐渐降低,扯断伸长率逐渐增加。     

螺杆结构对轮胎胶粉超声波脱硫工艺及性能的影响

采用负载超声波发生装置的同向旋转双螺杆挤出机对40目废旧轮胎胶粉（GTR）进行超声波脱硫,考察了两种不同结构螺杆对脱硫过程中的口型压力和功率消耗、脱硫GTR（DGTR）的外观形貌、流变性能、硫化特性及DGTR硫化胶力学性能的影响。结果表明,在13 μm超声波振幅和含较多捏合块部件螺杆的作用下得到的DGTR的凝胶含量、黏度及储能模量较低,说明含捏合元件的螺杆剪切作用更强,能使GTR获得更高程度的脱硫。该条件下所制得的DGTR硫化胶的拉伸强度和100%定伸应力较低,扯断伸长率较高。     

Effects of processing parameters on the properties of microwave‐devulcanized ground tire rubber/polyethylene dynamically revulcanized blends

This work aimed to evaluate the effects of processing parameters on properties of dynamically revulcanized blends based on 60 wt % of devulcanized ground tire rubber (GTR) and 40 wt % of high density polyethylene (HDPE). Devulcanization of the GTR was carried out in a system comprised of a conventional microwave oven adapted with a motorized stirring system with speed control. The resulting devulcanized GTR contained 26 wt % soluble in toluene. It was processed with HDPE in a twin screw extruder to produce a dynamically revulcanized blend. Processing parameters such as screw speed and feeding mode were varied. Their effects were evaluated based on tensile, dynamic mechanical, thermal and rheological properties, as well as on morphology. The results show the importance of the processing parameters involved in the production of blends with dynamically revulcanized rubber phase in the extruder, and good match between the residence time of the rubber and its revulcanization kinetics. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43503.     

Thermomechanical reclaiming of ground tire rubber via extrusion at low temperature: Efficiency and limits

Thermomechanical reclaiming of ground tire rubber (GTR) was performed at different temperatures (60, 120, and 180°C) using a co‐rotating twin‐screw extruder. Obtained samples were used in styrene‐butadiene rubber (SBR) blends. As reference samples, SBR compounds containing untreated GTR were used. Curing characteristics, static and dynamic mechanical properties, and morphology of the obtained blends were determined. The results show that the increase of barrel temperature during the thermomechanical reclaiming of GTR has a positive effect on the decrease of screw torque (lower machine load) and decrease of Mooney viscosity (better processing characteristics). However, mechanical properties and crosslink density of rubber revulcanizate decreased with increasing barrel temperature during the reclaiming process. SBR blends with 50 phr of reclaimed rubber showed increasing phase compatibility between SBR matrix and the reclaimed rubber, which was confirmed by mechanical properties and morphology measurements. J. VINYL ADDIT. TECHNOL., 22:213–221, 2016. © 2014 Society of Plastics Engineers     

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。     

酚硫化物/醇复合促进剂对废轮胎胶应力诱导脱硫反应的影响

在废轮胎胶(GTR)与三元乙丙橡胶(EPDM)熔融挤出过程中添加多烷基苯酚二硫化物(简称420)或/和仲丁醇作为脱硫促进剂,考察了在不同螺杆转速和挤出反应温度下脱硫促进剂对GTR与EPDM脱硫共混物(DGTR/EPDM)凝胶含量和溶胶分子链结构的影响,研究了DGTR/EPDM/丁苯橡胶(SBR)再硫化胶的相态结构及物理...     

Interfacial adhesion evaluation in (low‐density polyethylene)/elastomer blends

Low‐density polyethylene (LDPE) with different elastomers at a ratio of 50/50 wt% blends was prepared by using a co‐rotating twin‐screw extruder. Three kinds of elastomers were used: ground tire rubber (GTR), partially crosslinked butyl rubber (Kalar^®), and styrene‐butadiene‐rubber block copolymer (SBS; Kraton^®). For better characterization of interaction between polyethylene and elastomer, influence of the type of elastomer on the properties of compositions LDPE/elastomer was determined. In the studies, two types of partially crosslinked butyl rubber (differing over filler content and Mooney viscosity) and two types of SBS (differing over structure: linear/branched) were used. The influence of kind and type of elastomer on static mechanical properties (tensile strength, elongation at break, hardness), dynamic mechanical properties, thermal properties, and morphology of obtained compositions were characterized. LDPE/linear SBS copolymer blend had the best mechanical properties, as a result of better compatibility in comparison with other investigated blends. The reason for improved compatibility was an increase of mobility of chain segments in the amorphous phase of polyethylene associated with their partial plasticization by flexible polybutadiene blocks present in SBS copolymer. J. VINYL ADDIT. TECHNOL., 22:492–500, 2016. © 2015 Society of Plastics Engineers     

高掺量橡胶沥青的结构与性能

轮胎胶粉的多重交联网络限制了其在橡胶沥青中的胶粉掺量。用经螺杆反应挤出方法可控再生的再生胶可制备高掺量（质量分数不小于30%）橡胶沥青。通过溶胶含量、门尼黏度和基本性能测试及加工实况观察,并结合红外光谱和光学显微镜微观分析,探讨了胶粉的再生程度及用量对高掺量橡胶沥青结构与性能的影响。结果表明,再生过程中胶粉的化学键发生断裂,部分交联网络被破坏。与传统橡胶沥青相比,高掺量橡胶沥青的分散更均匀,加工流动性和高温储存稳定性均得以改善。提高胶粉的降解再生程度可明显提高其在沥青中的掺量,进一步提高改性沥青的低温柔性和高温抗变形能力,但易出现加工黏度的临界陡增现象。     

Preparation of thermoplastic vulcanizates based on waste crosslinked polyethylene and ground tire rubber through dynamic vulcanization

An environmental‐friendly approach called high‐shear mechanical milling was developed to de‐crosslink ground tire rubber (GTR) and waste crosslinked polyethylene (XLPE). The realization of partial devulcanization of GTR and de‐crosslinking of XLPE were confirmed by gel fraction measurements. Fourier transform infrared spectral studies revealed that a new peak at 1723.3 cm^?1 corresponds to the carbonyl group (? C?O) absorption was appeared after milling. The rheological properties showed that the XLPE/GTR blends represent lower apparent viscosity after mechanical milling, which means that the milled blends are easy to process. Thermoplastic vulcanizates (TPVs) could be prepared with these partially de‐crosslinked XLPE/GTR composite powders through dynamic vulcanization. The mechanical properties of the XLPE/GTR composites increased with increasing cycles of milling. The raw XLPE/GTR blends could not be processed to a continuous sheet. After 20 cycles of milling, the tensile strength and elongation at break of XLPE/GTR (50/50) composites increased to 6.0 MPa and 185.3%, respectively. The tensile strength and elongation at break of the composites have been further improved to 9.1 MPa and 201.2% after dynamic vulcanization, respectively. Re‐processability study confirmed the good thermoplastic processability of the TPVs prepared. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

5 种脱硫剂对废胎面胶粉脱硫效果的比较

用二苯二硫化物( DPDS) 、氨苯基二硫化物( APDS) 、二( 邻苯甲酰氨基) 二硫化物( DBADPDS) 、烯丙基二硫化物( DADS) 和Delink 等5 种脱硫剂对废胎面胶粉进行了力化学脱硫再生。结果表明,用DBADPDS 脱硫的胶粉具有较低的门尼黏度和较高的溶胶含量,脱硫效果显著。其他4 种脱硫剂脱硫效果由高到低的顺序依次为DPDS、Delink、DADS 及APDS。将40 份( 质量) 脱硫胶粉填充到丁苯橡胶/炭黑复合材料中,由DBADPDS 脱硫胶粉填充者具有较低的玻璃化转变温度和定伸应力及较高的扯断伸长率和拉伸强度,耐屈挠性能也比其他脱硫剂脱硫胶粉填充的胶料优异。扫描电镜照片显示DBADPDS 脱硫的胶粉与基质橡胶间的界面作用较强,交联网络更均匀。     

Structure and performance of reclaimed rubber obtained by different methods

Four different reclaiming methods involving important reclaiming factors such as temperature, shear force, and atmosphere were used to reclaim ground tire rubber. The structure and performance of the reclaimed rubber were investigated. The reclaimed samples were all found to be mixtures of three parts: the sol part, a loosely crosslinked gel part, and low molecular substances. For a reclaimed product to have both good processability and mechanical properties, the ideal structure should be that the sol fraction and its molecular weight (M_n) are as high as possible. However, the high sol fraction and high M_n cannot be reached at the same time because of the nonselective scission of the main chain and crosslink bonds. Thus, for a reclaimed rubber to have high quality, the presence of some amount of gel fraction is essential. Our preliminary results showed that the recommended reclaiming method would be a process under oxygen‐free atmosphere, without severe shear force, and at relative low temperature. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Devulcanization of waste tires using a twin‐screw extruder: The effects of processing conditions

During recent decades, for both economic and environmental reasons, recycling of waste tires that are based on SBR/NR has been widely considered. In this study the devulcanization process of the tread section of waste tires was carried out by using a twin‐screw extruder. The effects of barrel temperature and screw speed were investigated. Percent of devulcanization, sol fraction, and curing behavior of devulcanized samples were studied. After the addition of curing agents into the devulcanizates, the general behavior of the rheometry test for rubber compounds was observed. Percent of devulcanization and sol fraction depended on the screw speed and barrel temperature, respectively. The devulcanized samples were formulated with virgin rubber (15/85 wt% ratio) and re‐cured successfully. Tensile strength, elongation at break, compression set, hardness, and resilience were evaluated. It was found that the mechanical properties of the compound containing devulcanizates were slightly inferior to those of the virgin compound. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers     

The effect of devulcanization level on mechanical properties of reclaimed rubber by thermal‐mechanical shearing devulcanization

Ground tire rubber (GTR) with crosslinked structure has hardly any plasticity and processability, which makes its property very poor. Thermal‐mechanical shearing devulcanization method can effectively destroy the crosslinked structure and restore GTR a certain extent of plasticity and processability. This article investigated the characteristic and reprocessing performance of reclaimed rubber prepared through thermal‐mechanical shearing devulcanization. The relationship between the devulcanization level (indicated by gel fraction and crosslink density) and the mechanical property was analyzed by sufficient experiments. Fourier transform infrared spectroscopy and elemental analyzer studies revealed the chemical structure of GTR changed and many complex reactions occurred after devulcanization. The gel permeation chromatography indicated the specific changes of molecular weight and molecular weight distribution in devulcanization process. The differential scanning calorimetry revealed various vulcanized abilities and vulcanized structures of reclaimed rubber. The scanning electron microscope further confirmed the recovery of plasticity after devulcanization and the distinct vulcanized structures between revulcanizates. The determination of devulcanization level and mechanical properties verified that mechanical properties especially tensile strength reached to the optimum value only at an appropriate devulcanization level. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of rubber composites from ground tire rubber reinforced with waste‐tire fiber through mechanical milling

Composites made from ground tire rubber (GTR) and waste fiber produced in tire reclamation were prepared by mechanical milling. The effects of the fiber content, pan milling, and fiber orientation on the mechanical properties of the composites were investigated. The results showed that the stress‐induced mechanochemical devulcanization of waste rubber and the reinforcement of devulcanized waste rubber with waste‐tire fibers could be achieved through comilling. For a comilled system, the tensile strength and elongation at break of revulcanized GTR/fiber composites reached maximum values of 9.6 MPa and 215.9%, respectively, with 5 wt % fiber. Compared with those of a composite prepared in a conventional mixing manner, the mechanical properties were greatly improved by comilling. Oxygen‐containing groups on the surface of GTR particles, which were produced during pan milling, increased interfacial interactions between GTR and waste fibers. The fiber‐filled composites showed anisotropy in the stress–strain properties because of preferential orientation of the short fibers along the roll‐milling direction (longitudinal), and the adhesion between the fiber and rubber matrix was improved by the comilling of the fiber with waste rubber. The proposed process provides an economical and ecologically sound method for tire‐rubber recycling. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 4087–4094, 2007     

Dynamic reaction inside co‐rotating twin screw extruder. I. Truck tire model material/polypropylene blends

Waste ground rubber tire (WGRT) is a complex composite containing various elastomers, carbon black, zinc oxide, stearic acid, processing oils, and other curatives. Most of the waste ground rubber tire is composed of mainly natural rubber (NR) and styrene butadiene rubber (SBR) in varying proportions. Blending it with other thermoplastic materials is difficult due to the inherent thermodynamic incompatibility. But, the compatibility can be increased by making the reactive sites in WGRT with suitable chemicals under optimum condition of shearing inside a twin screw extruder and it is said to undergo a dynamic reaction inside the extruder. To understand the mechanism of dynamic reaction process of a rubber/polyolefin blend, the blending of a truck tire model material rubber with polyolefin was first tried before it was applied to waste WGRT material. It was observed that the blends of a truck tire model rubber material and PP thermoplastic are physical mixture of two incompatible polymers in which a continuous plastic phase is largely responsible for the tensile properties. The rubber particles are the dispersed phase. The large particle size and the poor adhesion of these rubber particles are believed to be liable for the poor tensile properties. In case of blends of truck tire model material with isotactic polypropylene the tensile properties are found to be lower than that of its PP‐g‐MA counterpart which can be attributed to the reaction of the MA with the carbon black particles. A schematic representation of the possible interactions has been proposed. The effect of addition of compatibilizers such as SEBS and SEBS‐g‐MA has also been studied. The tensile and TGA studies indicate that the polarity of SEBS and SEBS‐g‐MA induces an increase in the performance characteristics for both types of polyolefins but the intensity of this increase is higher in the PP‐g‐MA based blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 106: 3193–3208, 2007     

Continuous devulcanization of waste tires by using a Co‐rotating twin screw extruder: Effects of screw configuration,temperature profile,and devulcanization agent concentration

Recently, for reasons both economical and environmental, recycling of waste tires based on (styrene butadiene rubber)/(natural rubber) (SBR/NR) has been widely considered. Response surface methodology (RSM) has been used to predict SBR/NR devulcanization behavior in a co‐rotating twin screw extruder. In this study, variable parameters were barrel temperature, screw configuration, and content of devulcanization agent. A Box‐Behnken design for the three variables, at three levels, was chosen. The sol fraction of devulcanized rubber, Δtorque (difference between maximum and minimum curing torque), and mechanical properties of revulcanizate samples were considered as the responses. The results indicated that an increase of devulcanization agent content at a certain temperature caused the sol fraction to increase. Samples including a higher sol fraction showed a lower cross‐link density. Sol fraction for high shear rate screw configuration was lower than that for other screw configurations. Tensile strength of revulcanized rubber showed a decrease with a rise of devulcanization temperature. Moreover, a relationship connecting the residence time in the extruder with stagger angle and length of different kneading blocks were obtained. J. VINYL ADDIT. TECHNOL., 19:65–72, 2013. © 2013 Society of Plastics Engineers