Effect of chlorination of ground rubber tire on its compatibility with poly(vinyl chloride): Dielectric studies

Dielectric analysis (DEA) of molded ground waste rubber tire (GRT) and its chlorinated derivatives (Cl‐GRT) was undertaken. Dielectric spectra of Cl‐GRT show formation of a biphasic structure consisting of the rubbery phase and a hard phase whose relaxation occurs in the high‐temperature region. DEA of plasticized poly(vinyl chloride) (PVC) containing GRT and PVC containing Cl‐GRT was also undertaken. It is observed that PVC containing Cl‐GRT exhibits a higher loss factor in the high‐temperature region than does the PVC compound containing GRT, due to enhanced interaction between Cl‐GRT and PVC. While the activation energy for dielectric relaxation of PVC does not change when compounded with GRT, it does decrease when PVC is compounded with Cl‐GRT due to dipolar interaction. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 993–1000, 2002; DOI 10.1002/app.10320     

Melt‐processable rubber: Chlorinated waste tire rubber‐filled polyvinyl chloride

Chlorinated ground rubber tire (Cl‐GRT) particles were used as filler in a plasticized polyvinylchloride (PVC) to develop a melt‐processable rubber composition. Physical properties of the Cl‐GRT‐filled PVC compound showed improvement compared to the nonchlorinated counterpart. Interaction between Cl‐GRT and PVC was examined on the basis of results of stress relaxation, dynamic mechanical thermal analysis, and solvent swelling studies. The Cl‐GRT could be loaded upto 40 parts per hundred parts of PVC, and the composition still retains the elastomeric characteristics. The Cl‐GRT‐filled composite was found to be reprocessable like the unfilled PVC compound. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 622–631, 2002; DOI 10.1002/app.10352     

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     

Enhanced toughening of poly(propylene) with reclaimed‐tire rubber

The dynamic vulcanization of reclaimed‐tire rubber (RTR) and homopolypropylene (PP) was performed by melt‐mixing using either a sulfur crosslinking agent, maleic anhydride (MA), dicumyl peroxide (DCP), or the combination of MA and DCP, in two consecutive machines, first a two‐roll mill and then a counterrotating twin‐screw extruder. In the case of applying a sulfur crosslinking agent, it was demonstrated that the RTR/PP blend at the ratio of 30/70 had the highest impact strength. This could be attributed to the limitation of carbon black in the blend. When the combination of MA and DCP was applied, the result was higher impact strength of the blend at the same ratio. This could be attributed to not only the cohesion between the polymer chains in each phase, PP phase and rubber phase, but also the interfacial adhesion between PP and RTR chains in these two phases. For comparison, the GRT/PP blends with and without sulfur crosslinking agent were prepared as well. All these blends showed low impact strength, which was nearly the same as that of PP. The effects of different crosslinking agents on dispersion and distribution of rubber domain size, viscosity, and percentage crystallinity were also studied. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 510–515, 2004     

Thermoplastic elastomers from reclaimed rubber and waste plastics

Thermoplastic elastomeric compositions from reclaimed rubber and scrap plastics were prepared. The physical properties, dynamic mechanical properties, rheological behavior, and phase morphology of the blends were studied. A 50:50 rubber/plastic ratio was found to be the best for processability, ultimate elongation, and set properties. A sulfur‐accelerator system was found to be better than a peroxide system for dynamic crosslinking. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2035–2042, 2002     

胶粉/LLDPE弹性体合金的研制

系统研究了废胶粉（GRT）／线型低密度聚乙烯（LLDPE）弹性体合金（GRT／LLDPE）的配方，以及粒径，GRT含量，相容剂和硫化剂（DCP）用量对共混物力学性能的影响，结果表明，采用两阶共混法，当GRT／LLDPE共混比为：60：40，DCP用量为2份，相容剂马来酸酐三单体接枝物用量为3－5份时，所得弹性体合金力学性能最佳，弹性体合金的拉伸强度从简单共混物的5．8Mpa上升到11．1MPa，撕裂强度从39．4kN/m，上升到63．4kN/m，断裂伸长率从180％增加到260％。     

Thermoplastic elastomers based on recycled high‐density polyethylene,ethylene–propylene–diene monomer rubber,and ground tire rubber

High‐performance thermoplastic elastomers (TPEs), based on recycled high‐density polyethylene (HDPE^R), olefinic type ethylene–propylene–diene monomer rubber (EPDM), and ground tire rubber (GTR) treated with bitumen, were prepared by using dynamic vulcanization technology, and their structure–property relationships were investigated. It was established that special pretreatment of GTR by bitumen confers outstanding mechanical properties on the resulting TPEs. TPEs, containing GTR pretreated by bitumen, exhibit thermal behavior similar to that of the HDPE^R/EPDM basic blend in the temperature region up to about 340°C. Rheological measurements showed that bitumen acts as an effective plasticizer for the GTR‐containing TPEs. SEM, DSC, and DMTA results revealed improved adhesion between the particles of GTR treated by bitumen and the surrounding thermoplastic matrix, compared to that of the untreated GTR particles. It was concluded that bitumen acts as an effective devulcanizing agent in the GTR treatment stage. In the following steps of TPE production, bitumen acts simultaneously as a curing agent for the rubber components (EPDM/GTR) and as a compatibilizer for the blend components. GTR‐containing TPEs, prepared by extrusion technology, were reprocessed (by passing through the extruder six times) without any observable changes in their tensile properties, thermal stability, and melt viscosity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 659–671, 2005     

Effects of Extruder Parameters and Compositions on Mechanical Properties and Morphology of Maleic Anhydride Grafted Polypropylene/Waste Tire Blends

A co-rotating twin screw extruder was used for blending thermoplastic elastomeric blends of ground rubber tire (GRT) and maleic anhydride grafted polypropylene (PP-g-MA). The dynamic reaction occurring between the blends necessitates a study of the processing parameters of the extruder. The effects of the extruder screw configurations, screw speed, compatabilizer and blend ratios on the mechanical properties, and morphology was studied. Out of the four different screw configurations A, B, C, and D, screw D with reverse flow elements was found to be highly efficient with respect to mechanical properties, particularly at 100 rpm screw speed. SEM studies revealed that GRT and PP-g-MA are thermodynamically miscible under optimized screw configuration and processing condition of 100 rpm screw speed. SEM studies also show that the addition of compatibilizer increases the miscibility and, consequently, the mechanical properties. Finally, a composition involving GRT/PP-g-MA/SEBS-g-MA as 65/35/10 by weight was found to be optimum.     

胶粉/聚烯烃类热塑性硫化胶共混材料的研究

研究胶粉/聚烯烃类热塑性硫化胶(TPV)共混材料的力学性能、耐油性、热稳定性、动态力学性能及材料的界面増容,并采用扫描电镜对共混材料的断面微观形貌进行了表征分析。研究结果表明:TPV/胶粉共混材料的力学性能随着胶粉粒径的减小而提高;增容剂PP-g-MAH可有效地改善胶粉与TPV的相容性,提高共混材料的力学性能;同时,胶粉和增容剂的加入增强了TPV的耐油性。     

Properties of silica‐filled styrene‐butadiene rubber compounds containing acrylonitrile‐butadiene rubber: The influence of the acrylonitrile‐butadiene rubber type

Because silica has strong filler‐filler interactions and adsorbs polar materials, a silica‐filled rubber compound exhibits poor dispersion of the filler and poor cure characteristics in comparison with those of a carbon black‐filled rubber compound. Acrylonitrile‐butadiene rubber (NBR) improves filler dispersion in silica‐filled styrene‐butadiene rubber (SBR) compounds. The influence of the NBR type on the properties of silica‐filled SBR compounds containing NBR was studied with NBRs of various acrylonitrile contents. The composition of the bound rubber was different from that of the compounded rubber. The NBR content of the bound rubber was higher than that of the compounded rubber; this became clearer for NBR with a higher acrylonitrile content. The Mooney scorch time and cure rate became faster as the acrylonitrile content in NBR increased. The modulus increased with an increase in the acrylonitrile content of NBR because the crosslink density increased. The experimental results could be explained by interactions of the nitrile group of NBR with silica. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 385–393, 2002     

Thermoplastic elastomeric composition based on ground rubber tire

Ground rubber tire (GRT) is a particulate vulcanizate consisting mainly of rubber hydrocarbon and fillers. Rubber hydrocarbon of GRT (rGRT) has been used as a partial substitute for EPDM rubber in a dynamically vulcanized EPDM/acrylic‐modified HDPE (A‐HDPE) blend. The blends with higher rubber content show poor processability and physical properties, while the compositions with higher plastic content behave like toughened plastics. However, the 60:40 rubber/plastic blend was found to behave as a thermoplastic elastomer, and it was observed that 50% of EPDM can be replaced by rGRT without deterioration in properties.     

Properties of silica/clay filled heavy‐duty truck tire thread formulation

A tire thread formulation for heavy‐duty trucks containing SBR/BR rubber blend and varying proportions of silica/clay fillers including a silane‐coupling agent have been investigated. The various mixes were compounded in a Banbury ‘O’ mixer and vulcanized using the EV‐system. Silica/clay (80/0) served as the control mix. The oscillating disc rheometer (ODR) was used in determination of cure characteristics. Substitution of silica (80 phr) with china clay up to 40 phr increased the cure rate of the rubber blend mixes as well as their maximum torque level (T_max). T_max was observed to be highest at a filler blend ratio of 40/40 phr. Synergism between silica and clay at this filler blend mixture is suggested to be responsible for the observation. The heat buildup was reduced from 43 to 20°C as the clay content increased. Results also showed that the rubber blend compound containing silica/clay (60/20) filler blend in the stated ratio exhibited the best balance of properties in the critical parameters such as the absolute torque level (69.5 dNm), heat buildup (39°C), and abrasion resistance (0.574 mg.loss/1,000 rev). The rate of depreciation of abrasion resistance of rubber blend compound as the clay content increased was found to be 0.035 mg loss/1,000 rev as silica is substituted with one part of china clay phr. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1024–1028, 2004     

Surface‐grafting of ground rubber tire by poly acrylic acid via self‐initiated free radical polymerization and composites with epoxy thereof

Commercially available recycled ground rubber tire (GRT) particles, found to contain persistent mechano‐free radicals confirmed by electron paramagnetic spectroscopy for the first time self‐initiates free radical polymerization of acrylic acid (AA). The poly acrylic acid (PAA) grafted GRT (PAA‐g‐GRT) was confirmed by Attenuated Total Reflection Fourier Transform Infrared spectroscopy, X‐ray photoelectron spectroscopy, and thermogravimetric analysis (TGA). Epoxy composites using the PAA‐g‐GRT as filler were prepared and their mechanical properties were studied. The PAA‐g‐GRT/epoxy composite showed higher mechanical properties with an increase of modulus up to 180% as compared with the neat GRT/epoxy composite. Surface morphology of GRT, neat GRT/epoxy, and PAA‐g‐GRT/epoxy composites were analyzed by scanning electron microscopy. This technology introduces a new concept to functional and reactive recycling and the cost effective utilization of renewable resource green materials. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers     

Macromolecular modification of EPDM: Wettability,miscibility, and morphology study

The present investigation deals with studies on wettability, miscibility, and morphology of the macromolecularly modified EPDM. Two different maleated EPDM rubbers (grafted rubber) were chosen (0.5 and 1% maleation) for such modification and they were used in various proportions. Wettability of the rubber substrate, as observed from dynamic contact angle measurement, was improved using these grafted rubbers. Results of X‐ray photoelectron spectroscopy showed an increase in oxygen level with higher levels of grafted rubber in the blends. Morphology study by transmission electron microscopy showed a smaller domain size for the blend with higher maleic anhydride content in the grafted rubber. The viscosity versus blend ratio results showed a negative deviation behavior for blends with 1% grafted rubber, whereas a positive negative deviation behavior was observed in blends with 0.5% grafted EPDM. As the strength of interaction increased, the glass transition shifted to a higher temperature. All blends were heterogeneous, as indicated by different degrees of dispersion. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2647–2661, 2001     

A rheometrical technique to study the swelling kinetics of vulcanized rubber particles by paraffinic solvents using a torque rheometer

The solvent uptake by vulcanized rubber particles was studied through a swelling technique by using a torque rheometer to record torque versus time curves, with good repeatability. Several experiments were performed to study the effects of varying the solvent/rubber ratio, the solvent type, and the rubber nature. The effects of the materials alone were also studied. A four‐parameter mathematical model was developed, with a physical significance assigned to each of the parameters, and was compared with experiments. The model was found to fit well with the experimental results, therefore, allowing the physical processes involved in the solvent swelling of rubber particles to be investigated through model parameters. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 142–153, 2004     

Synthesis and characterization of maleated rosin‐modified fluorosilicone resin and its fluorosilicone rubber

Imide‐containing vinyl fluorosilicone resin (MR‐VFS) was synthesized from maleated rosin (MR). And then, with MR‐VFS as a new polar cross‐linking agent in a heat curable fluorosilicone rubber composition, a series of maleated rosin‐modified fluorosilicone rubbers (MR‐FSR) were obtained. The effects of MR‐VFS on the mechanical properties, oil resistance, thermal stability, and low‐temperature performance were studied in detail. It was found that MR‐VFS could increase the tearing strength and high‐temperature thermal stability of fluorosilicone rubber. When the MR‐VFS weight content reached to 2 wt %, the tearing strength of MR‐FSR increased by 20.1% compared with that of common fluorosilicone rubber. However, MR‐FSR showed a similar low‐temperature resistance and a little worse oil resistance. The morphological study showed that incorporation of maleated rosin could intensify the microphase separation of fluorosilicone rubber. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41888.     

Dynamic reaction inside co‐rotating twin screw extruder. II. Waste ground rubber tire powder/polypropylene blends

In this article, dynamic reaction of waste ground rubber tire powder/PP blends with compatibilizers is extended to commercially available waste rubber Viz. Ground rubber tire and PP for the possibility of getting recycled material with good mechanical properties. In the first part of the article it was shown that the compatibility of model material/PP blends has greatly improved. In this article, extensive studies have been carried out to study the effect of compatibilizers, in‐situ compatibilization of immiscible waste ground rubber tire (WGRT) powder/polyolefin blends of various concentrations was investigated by means of extrusion process using a co‐rotating twin screw extruder. It was observed that addition of small amounts of compatibilizers like SEBS‐g‐MA to the blends of WGRT and PP‐g‐MA can result in better mechanical properties than the blends with isotactic PP. The blends of WGRT powder and PP‐g‐MA with compatibilizer have better adhesion than those of isotactic PP blends as revealed by the morphological studies using AFM and SEM. The betterment in properties can be attributed to the presence of functional group, maleic anhydride in PP‐g‐MA. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

废聚丙烯/废轮胎胶粉/废尼龙短纤维复合材料 Ⅰ.配方

用双螺杆挤出机制备了废聚丙烯/废轮胎胶粉/废尼龙短纤维(WPP/GRT/WSF)复合材料,通过正交实验得出了制备该复合材料的最佳配方,讨论了增容剂用量、氯化聚丙烯的含氯质量分数、GRT用量及其粒径、WSF用量及预处理对该复合材料力学性能的影响。结果表明,制备该复合材料的最佳配方(质量份,下同)是WPP100,GRT30,WSF8,二甲基二硫代氨基甲酸锌、二硫化二苯并噻唑、多乙烯多胺及重油用量依次为0.6,1.2,0.3,2,聚丙烯接枝马来酸酐、氯化聚丙烯用量依次为8,4;在最佳配方下,该复合材料的非缺口冲击强度为25.2kJ/m2,拉伸强度为13.6MPa;GRT用量为30份时,该复合材料的拉伸强度和非缺口冲击强度最大,GRT的最佳粒径为40目;WSF经D法预处理后,提高了该复合材料的力学性能,拉伸强度为16.3MPa,非缺口冲击强度为27.8kJ/m2。     

Organomodified kaolin as a reinforcing filler for natural rubber

China clay (kaolin) has been modified with sodium salt of rubber seed oil (SRSO). SRSO was characterized using X‐ray diffraction (XRD), infrared spectroscopy (FTIR), and differential thermal analysis (DTA). XRD of the unmodified and SRSO‐modified kaolins showed an increase in the d‐(001) spacing of kaolin platelets from 7.15 to 14 Å. FTIR spectroscopy indicated possible grafting of the organic moiety of rubber seed oil (RSO) onto the clay surface. DTA of the SRSO‐modified kaolin indicated that the SRSO is more strongly bound in a constraint environment within the lamellae of kaolin. Natural rubber (NR) mix containing 10 phr of SRSO‐modified kaolin was found to cure faster than that of a similar mix containing unmodified kaolin. NR vulcanizates containing SRSO‐modified kaolin showed considerable increase in tensile modulus, tensile strength, and elongation at break indicating its potential as an organomodified nanofiller. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Graft copolymerization of acrylonitrile and methyl methacrylate monomer mixtures on crumb natural rubber

Graft copolymerization of mixtures of acrylonitrile and methyl methacylate on crumb natural rubber was carried out in toluene at 60°C. The nitrogen content of the grafted copolymer was determined by elemental analysis and used to estimate the composition of the copolymer samples. It was found that the amount of acrylonitrile monomeric units incorporated into the polymer was disproportionately lower than the acylonitrile content of the feed and explanations in terms of the e‐value of the monomers and the inherent heterogenous nature of the polymerization mixture were offered. The miscibility of the natural rubber‐g‐polyacrylonitrile‐co‐poly(methyl methacrylate) with poly(vinyl chloride) was studied by viscometry, differential scanning calorimetry, and phase contrast microscopy. It was found that the natural rubber‐g‐polyacrylonitrile‐co‐poly(methyl methacrylate) formed semimiscible blends with poly(vinyl chloride). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1872–1877, 2002; DOI 10.1002/app.10474