Tire Rubber Powder Research Articles

Grafting of hyperbranched poly(amidoamine) onto waste tire rubber powder and its potential application as the curing agent for epoxy resin

To realize the high-valued application of waste tire rubber (WTR), hyperbranched poly(amidoamine) (PAMAM) were synthesized from the surface of WTR powders to endow its chemical reactivity. The hyperbranched PAMAM-grafted WTR powders containing a large amount of amine groups on their surface were obtained through “divergent procedure.” First, methyl methacrylate-grafted WTR powders (MMA-g-WTR) were prepared by ozone-induced grafting polymerization. Afterwards, Michael reaction and subsequent amidation reactions were carried out repetitively to obtain hyperbranched PAMAM chains grafted from the surface of the MMA-g-WTR powders. The resulting hyperbranched PAMAM-grafted WTR powders exhibit good dispersibility in water. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis demonstrate the successful grafting of hyperbranched PAMAM on WTR surface. The hyperbranched PAMAM-grafted WTR powder could be utilize as curing agent and potential toughener for epoxy resin due to abundant amine groups and elastomeric feature of WTR. Differential scanning calorimetry shows that the hyperbranched PAMAM-grafted WTR powders can be used as effective curing agent for epoxy resin. Copyright © 2011 John Wiley & Sons, Ltd.

Cocombustion of Pulverized Coal with Waste Plastic and Tire Rubber Powders

The generation of scrap tires in the world is approximately 1 billion per year and is set to increase in the foreseeable future as the number of cars on the roads increases. In this paper we present results from a pilot scale study on the cofiring of fine tire rubber (FTR) powder and plastic (high-density polyethylene, HDPE) with pulverized coal (PC) with a view to an application in power generation as an alternative to biomass, particularly their role in the combustion behavior of PC. We have performed experiments with a South African (SAf) coal and a South American (SAm) coal of different composition for a range of cofiring levels, up to 25%, and several configurations of combustion air distribution (air-staging). The fuels were fired through the burner and particular regard was paid to the effect on CO2, NOx, SO2, and carbon burnout. The results show that coal quality has a significant role during cofiring. In present investigations when HDPE was cofired with the SAm coal, a significant reduction in NOx was observed. Lower NOx emissions are achieved due to the different combustion behavior of the fuels. That is, modifying the primary combustion zone environment makes it more difficult for the intermediate HCN and NH3 species to oxidize to NOx due to the reduced O2 concentration at the point of fuel-N release in the flame. The influence of the tire-N content is thought to be small in the flames studied. We have seen around 20% NOx reductions when cofiring tire with the SAf coal for a 20% tire/coal cofiring ratio but insignificant NOx reductions when cofiring tire with SAm coal under the same conditions, indicating similar combustion characteristics and flame dynamics. In all cases, good burnout was achieved with less than 8% carbon in ash. The reduction of NO by the cofiring of tire-coal and plastic-coal fuel blends was further compared to historical literature involving the cofiring of biomass. It is noted that the ignition behavior of fuels of tire and plastic may differ to that of biomass; however, the overall reduction in NO is still observed in both cases. Historical air-staged experiments involving the cofiring of biomass were not able to provide similarly high reductions of NO to the staged cofiring of tire-coal and plastic-coal fuel blends. It is thought that the particle size of the biomass fired is a significant factor that is influencing the NO reduction efficiencies within a staged flame.

Effects of Salt Corrosion and Freeze-Thaw Cycle on Rubberized Cement-Soil

In order to improve salt corrosion and frost resistance of cement-soil, the waste tire rubber powder was mixed into cement-soil to form rubberized cement-soil. In the salt corrosion and freeze - thaw cycle (SCFT) conditions, compressive strength of rubberized cement-soil increases first and then decreases with rubber content increasing. The more numbers of SCFT cycles, the more strength slip increases. But in high concentration conditions, the strength of rubberized cement-soil with 5%-10% rubber content reduces. With the solution concentration or SCFT cycles number increasing, peak stress of rubberized cement-soil and common cement-soil gradually reduces, but strength slip of rubberized cement-soil is lower than of cement-soil. Studies indicate that the performance of rubberized cement-soil surpasses common cement-soil decided by the relationship between rubberized cement-soil skeleton elastic behavior and coupling expansive force.

Enhancement of processability and foamability of ground tire rubber powder and LDPE blends through solid state shear milling

The foamed composites made from low-density polyethylene(LDPE) and ground tire rubber(GTR) powder using azodicarbonamide as chemical blowing agent have been investigated. Solid state shear milling was used to enhance the processability and foamability of LDPE/GTR blends by a pan-mill type mechanochemical reactor. First the blends of LDPE/GTR were prepared by co-milling, then the samples were melt-mixed in a Brabender Plasti-Corder, saturated with blowing agent, crosslinking agent and blowing co-agent, and finally the saturated specimens were expanded during the pressure-quench process. The results indicated that the mechanical properties of the LDPE/GRT foamed composites were improved, and the blends of co-milled GTR and LDPE powder showing better processability and foamability than those obtained in a conventional melt-mixing manner, as indicated by the rheological and morphological studies.

Prediction of mechanical properties of waste polypropylene/waste ground rubber tire powder blends using artificial neural networks

Recycling represents a valid alternative to the disposal of post-consumer materials if it is possible to obtain new materials with good properties. In this work, waste polypropylene (WPP)/waste ground rubber tire (WGRT) powder blends were studied with respect to the effect of bitumen and maleic anhydride-grafted styrene–ethylene–butylene–styrene (SEBS-g-MA) content by using the design of experiments (DOE) approach, whereby the effect of the four polymers content on the final mechanical properties were predicted. Uniform design method was especially adopted for its advantages. Optimization was done using hybrid artificial neural network–genetic algorithm (ANN–GA) technique. The results indicated that the blends show fairly good ductibility provided that it had a relatively higher concentration of bitumen and SEBS-g-MA under the studied condition. A quantitative relationship was presented between the material concentration and the mechanical properties as a set of contour plots, which were confirmed experimentally by testing the optimum ratio.

Research on Mechanical Performance of Roof Tiles Made of Tire Powder and Waste Plastic

The typical roof tiles made from soil or clay will be limited because it destroyed the farmland. On the other hand, the old tire and waste plastic increase year and year, which bring a serious environmental problem. So the roof tiles made from old tire and waste plastic will help a lot to decrease above environmental pressure. To get a suitable formula of roof tiles made from waste rubber tire powder and waste plastic, the present article studied mechanical performance of a series of composites. Then a preferred formula was got through comparing the mechanical performance.

Prediction of mechanical properties of polypropylene/waste ground rubber tire powder treated by bitumen composites via uniform design and artificial neural networks

Polypropylene (PP)/waste ground rubber tire powder (WGRT) composites were studied with respect to the effect of bitumen and maleic anhydride-grafted styrene–ethylene–butylene–styrene (SEBS-g-MA) content by using the design of experiments (DOE) approach, whereby the effect of the four polymers content on the final mechanical properties were predicted. Uniform design method was especially adopted for its advantages. Optimization was done using hybrid artificial neural network–genetic algorithm (ANN–GA) technique. The results indicated that the composites showed fairly good ductibility provided that it had a relatively higher concentration of bitumen and SEBS-g-MA under the studied condition. A quantitative relationship was presented between the material concentration and the mechanical properties as a set of contour plots, which were confirmed experimentally by testing the optimum ratio.

Effects of waste ground rubber tire powder (WGRT) and chemical blowing agent content on the cell morphology and physicomechanical properties of injection‐molded polypropylene/WGRT foams

AbstractMicrocellular polypropylene (PP)/WGRT blends, a new outlet for the recycling of waste tire rubber, were prepared in an injection‐molding process by using a chemical blowing agent. The effects of WGRT content and chemical blowing agent content on the density, cell morphology, and physicomechanical properties of the foamed PP/WGRT blends were investigated. The foam morphologies were characterized in terms of void fraction, average cell size, and cell density. The results indicated that both the WGRT and the blowing agent content had huge effects on the cell morphology and tensile properties of the PP/WGRT foams. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers

Rheological Property of Bitumen Modified by the Mixture of the Mechanochemically Devulcanized Tire Rubber Powder and SBS

The mechanochemically devulcanized ground tire rubber (m-GTR) prepared by solid-state mechanochemical reactor was used in the modification of bitumen with styrene-butadiene-styrene block (SBS) copolymer powder. The conventional properties (such as penetration index, softening point, 5°C ductility, and aging test) and rheological properties of bitumens modified by 8, 10, and 12 wt % m-GTR/SBS were investigated in this paper. The conventional properties except penetration of m-GTR/SBS modified bitumen were improved, compared with 5.5 wt % SBS modified bitumen. Rheological data demonstrated that all of the testing results of 10 wt % m-GTR/SBS modified bitumen were better than those of SBS modified bitumen under the condition of high temperature. The scanning electron microscope observation of the fractured surfaces showed that the m-GTR/SBS mixed powder had a better interface adhesion with matrix than SBS.

Partial replacement of NR by GTR in thermoplastic elastomer based on LLDPE/NR through using reactive blending: Its effects on morphology, rheological, and mechanical properties

AbstractAttempts have been made to use different amount of ground tire rubber (GTR) powder as a partial substitute for natural rubber (NR) in thermoplastic elastomer based on linear low‐density polyethylene (LLDPE, 60 wt%) and NR (40wt%). Maleic anhydride (MA) and dicumyl peroxide (DCP) were used, during melt mixing of the compound, to modify GTR and vulcanize the rubber phases of the blends. Morphology of the blends was studied by scanning electron microscopy and rheological behavior investigated through rheomechanical spectroscopy. Mechanical properties of the blends were also measured, and the effect of GTR concentration on properties was evaluated. Obtained results showed that modification of GTR with MA and using DCP in the blends containing GTR improves the bonding between GTR and matrix. This leads to a distinctive rheological behavior and enhances tensile strength and elongation at break compared to its corresponding simple blend. It can be said that using of MA and DCP during melt mixing of thermoplastic elastomers based on LLDPE/NR containing GTR, concludes to a better dispersion of GTR and formation of morphology similar to that of a dynamic vulcanized thermoplastic elastomer, which improves interfacial bonding between phases and causes a dramatically increase in mechanical properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Effects of formulation and processing parameters on the morphology of extruded polypropylene‐(waste ground rubber tire powder) foams

AbstractThis paper presents an experimental study of the foaming behavior of polypropylene (PP)/(waste ground rubber tire powder) (WGRT) blends when using a chemical blowing agent in an extrusion foaming process. The effects of formulations (i.e., WGRT content, blowing agent content, compatibilizer) and the processing parameters (i.e., die temperature, screw speed) on the void fraction, average cell size, cell density, and cell morphology of the PP/WGRT foams were investigated. The blowing agent loading affected the cell structure of the foams and the average cell size, and the void fraction increased with increasing blowing agent loading. Both increasing the screw speed and decreasing the die temperature could establish a high pressure drop in the extruder die, and these were beneficial to the foaming extrusion. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers

Expanded Waste Ground Rubber Tire Powder/Polypropylene Composites: Processing-Structure Relationships

The usage of waste tire powder as dispersed phase in polypropylene matrix offers an interesting opportunity for recycling of the waste tire. In order to obtain ‘value added products’ from polypropylene (PP)/waste ground rubber tire powder (WGRT) composites, in this study, the processing of foamedPP/WGRT composites was investigated using a single-screw foam extrusion setup and chemical blowing agent. The regression models were constructed to study the relationships between the foam structure (i.e., void fraction, average cell size, and cell density) of foamed PP/WGRT composites, the processing conditions (extruder’s die temperature and screw speed), and the formulation compositions (WGRT content and blowing agent concentration) by applying a four-factor central composite design (CCD) statistical approach. The response surface plots generated using the regression models allow the rapid selection of the proper process parameters to obtain PP/WGRT composite foams with the desired density and morphology.

Microcellular Structure of PP/Waste Rubber Powder Blends with Supercritical CO2 by Foam Extrusion Process

A new approach towards the recycling of waste ground rubber tire (WGRT) powder was demonstrated in this study by introducing the polypropylene/ waste ground rubber tire (PP/WGRT) foaming method by using CO2 as the foaming agent in an extrusion foaming process. The regression models were constructed to study the relationships between the foam structure (i.e., void fraction, average cell size, and cell density) of foamed PP/WGRT blends, the processing parameters (extruder’s die temperature and CO2 concentration), and WGRT content by applying a three-factor central composite design (CCD) statistical approach. The response surface plots generated using the regression models allow the rapid selection of the proper process parameters to obtain microcellular PP/WGRT blends with the desired density and morphology.

Study of microcellular injection-molded polypropylene/waste ground rubber tire powder blend

Microcellular polypropylene/waste ground rubber tire powder blend processing was performed on an injection-molding machine with a chemical foaming agent. The molded samples produced based on the design of experiments (DOE) matrices were subjected to tensile testing and scanning electron microscope (SEM) analyses. Molding conditions and waste ground rubber tire (WGRT) powder have been found to have profound effects on the cell structures and mechanical properties of polypropylene (PP) and waste ground rubber tire powder composite samples. The result shows that microcellular PP/WGRT blend samples exhibit smaller cell size and higher cell density compare with polypropylene resin. Among the molding parameters studied, chemical foaming agent weight percentage has the most significant effect on cell size, cell density, and tensile strength. The results also suggest that tensile strength of microcellular PP/WGRT composites is sensitive to weight reduction, and skin thickness.

Improvement of the properties of ground tire rubber (GTR)‐filled nitrile rubber vulcanizates through plasma surface modification of GTR powder

AbstractThe surface modification of ground tire rubber (GTR) powder to enhance its adhesion to nitrile rubber (NBR) vulcanizates was investigated. The hydrophobic surface of GTR powder has been transformed to a hydrophilic one through atmospheric pressure dielectric barrier discharge (DBD). The water contact angle dropped markedly from 116 to 0° after being treated for more than 10 s. Attenuated total reflectance Fourier transform infrared spectral (ATR‐FTIR) studies revealed the increase in peak intensity at 3298 and 1640 cm−1 that correspond to OH and CC, respectively, on the surface of the GTR powder. The X‐ray photoelectron spectroscopic (XPS) analysis further confirmed the presence of oxygen containing polar functional groups on the surface of the GTR powder after atmospheric plasma treatment. The improvement in tensile strength and tear strength was observed for the modified GTR‐filled NBR vulcanizates, which is attributed to the enhanced interfacial interaction between modified GTR and NBR matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Characterization of the properties of thermoplastic elastomers containing waste rubber tire powder

The aim of this research was to recycle waste rubber tires by using powdering technology and treating the waste rubber tire powder with bitumen. It has been proven that the elongation at break, thermal stability and processing flowability of composites of polypropylene (PP), waste rubber tire powder (WRT) and bitumen composites are better than those of PP/WRT composite. A comparative study has been made to evaluate the influence of bitumen content and different compatibilizers on the properties of PP/WRT/bitumen composites, using a universal testing machine (UTM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and a capillary rheometer. The results suggested that the properties of PP/WRT/bitumen composites were dependent on the bitumen content and the kind of compatibilizer used.

Preparation and characterization of thermoplastic elastomers (TPEs) based on waste polypropylene and waste ground rubber tire powder

AbstractIn this article, the possibility of obtaining the recycled material based on waste polypropylene (WPP) and waste ground rubber tire powder (WGRT) has been studied. It has been proved that partially replacing WPP with PP-g-MA increased the elongation at break of WPP/WGRT blends, whereas decreased the thermal stability. The presence of compatibilizer increased the elongation at break and thermal stability of WPP/WGRT blends, whereas decreased the processing flowability, as revealed by using universal testing machine (UTM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and capillary rheometer. Moreover, the tendency of the change became more obvious with the content of PP-g-MA and compatibilizer or with the combination of PP-g-MA and compatibilizer. In addition, the improvement of the nonpolar compatibilizer (SEBS) in properties of WPP/WGRT blends was better than that of the polar compatibilizer (SEBS-g-MA).

Dynamic reaction involving surface modified waste ground rubber tire powder/polypropylene

AbstractThe surface of waste ground rubber tire (WGRT) powder has been modified with by allylamine via an ultraviolet (UV) treatment. The degree of grafting of the modified‐WRGT are confirmed by the Fourier Transform Infrared spectroscopy (FTIR), scanning electron microscopy, energy dispersive X‐ray analysis, thermogravimetric analysis, and surface energy measurements. And then they incorporated into the polypropylene (PP) matrix. The effects of UV radiation time, WGRT loading, and allylamine concentration on the mechanical properties of the composites are measured. Mechanical properties are influenced as a function of UV radiation time, WGRT loading, and allylamine concentrations. The chemical interactions between grafted WGRT and PP matrix are investigated by X‐ray diffraction and FTIR. They show change of the crystallinity of the PP and the chemical reaction between WGRT and the PP. POLYM. ENG. SCI., 2009. © 2008 Society of Plastics Engineers

Polypropylene–waste ground rubber tire powder microcellular composites: Effect of processing variables on morphology and physico‐mechanical properties

AbstractMicrocellular composites made from polypropylene and waste ground rubber tire powder using azodicarbonamide as chemical blowing agent have been investigated. A small quantity of SEBS‐g‐MA has been added as compatibilizer. The effect of variation in processing variables such as pressure, heating time, and operating variables such as blowing agent and crosslinker concentrations have been investigated to establish a relationship between the structure and morphology of the microcellular composite and ultimate performance characteristics such as tensile strength, tear strength, and elongation at break. The results indicate that both processing and operating variables have tremendous effect on the morphological features such as average, minimum, and maximum cell size as observed from scanning electron microscopy. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

Compatibilizing thermoplastic/ground tyre rubber powder blends: Efficiency and limits

This paper deals with the compatibilization between recycled HDPE matrix and ground tyre rubber powder, through a free radical mechanism, by adding a peroxide. Mechanical tests show competition between the crosslinking of HDPE and the formation of interfacial bonding. The addition of more than 1 %wt of peroxide results in a strong improvement of interfacial adhesion and elongation at break. The performance is also compared to that resulting from gamma irradiation of the same blends. In the second part of this article, experimental tests and simulation by finite elements analysis were performed and showed the non-possibility of obtaining a “thermoplastic elastomer” by blending and compatibilizing HDPE and ground tyre rubber powder, since perfect interfacial adhesion still results in decohesion between matrix and particles.