Due to the technical evolution of tires, currently most automotive tires do not have an inner tube. However, truck, motorcycle and bicycle tires still use tires with inner tubes, mostly made of synthetic elastomeric material, which guarantees good potential for air restriction or longer periods for tire pressure failure. This work aims to study changes in the mechanical properties of a truck inner tire, after its exposure to gamma rays, to promote the subsequent recycling of the material. The choice of ionizing radiation is due to its ability to modify the structure and properties of materials, in addition to its applicability in recycling/recovering rubber. For the characterization of the samples, doses of 5, 10, 15, 20, 25 and 30 kGy were applied, and after irradiation as a sample, they were tested using the following characterization methods: traction and elongation at break, hardness, thermal aging and elemental analysis. Observed that is a decrease in the values of the mechanical properties of the samples after irradiation, mainly at doses greater than 10 kGy.

Thermoplastic elastomers (TPEs), based in PP (Polypropylene) / EPDM (Ethylene Propylene Diene Monomer) have as purpose improving PP resistance and impact, aiming to a more comprehensive use in automotive market, among edifications, construction and packaging sectors, due to their recyclability properties. PP is a commodity, with a high melting point, high mechanical resistance and low density, posing a balance between physical and mechanical properties; in addition, it shows an easy processing, at low cost. In order to minimize this deficiency, EPDM, an impact modifier, can be used. Nevertheless, most of polymeric blends are incompatible and immiscible, i.e., show a mutual and limited solubility and in most of cases, a high interfacial tension. However, there is a relatively low interfacial tension (force which acts on transformation of a continuous structure in a dispersion) between PP and EPDM (approximately 0.3 mN.m-1), reducing the rate of breakup and facilitating the build-up of a continuous structure. This work aims to the study of compatibility of PP and EPDM blends and variation of mechanical properties, emphasizing that many properties of thermoplastic elastomers can be processed according with conventional thermoplastics methods: herein, PP/EPDM blends, 90/10, 80/20, 70/30 and 50/50 were characterized according to: Mechanical essays, Differential Scanning Calorimetry, Thermogravimetric Analyses, Melt Flow Index, Izod Impact Strength and Dynamic mechanical Analyses.

Bio-filler from eggshells as reinforcement of bio-based polymers are based on their benefits as adequate strength and stiffness, besides friendly, degradable and renewable environment. Eggshell is an agricultural waste considered as garbage, contributing to pollution; nevertheless, it can be transformed into bio-calcium carbonate, acquiring new values. As biodegradable polymers, there were chosen PLA (poly-lactic-acid) and PBAT (butylene adipate co-terephthalate), thermoplastics capable to be processed via conventional methods. PLA is a linear, aliphatic thermoplastic polyester, high in strength and modulus, but brittle. PBAT is a synthetic polymer, very flexible, based on fossil resources with high elongation at break, but low strength. It will be required the use of compatibilizers, for reducing interfacial tension exhibited by PLA/PBAT immiscible blend, considering their extreme glass transition temperatures: 62 o C for PLA and – 30 o C for PBAT. Herein it was used ionizing radiation for inducing compatibilization by free radicals, improving dispersion and adhesion of blend phases, without using chemical additives, at room temperature. PLA, acting as compatibilizer, was previously e-beam and gamma radiated, at 150 kGy. PBAT/PLA 50/50 blend with 15 phr of bio-filler from avian eggs 125 µm particle size and both compatibilizers were homogeneized in a co-rotating twin-screw extruder, within a temperature profile 120 to 145 o C, from hopper to die. Characterization involved: Differential Scanning Calorimeter, Thermogravimetric Analyses, Fourier Transform Infrared Spectroscopy, Wide Angle X-Ray Diffraction, Tensile Strength and Elongation at Break.

In order to minimize impacts caused to environment and to save natural resources, especially from non-renewable sources, recycling of polymeric materials has been object of study. In this scenery, are included elastomeric materials, such as rubber, especially used in tires manufacturing, considering that pneumatic industry consumes around 60% of rubber production. Taking into account that final tires destination is a requirement based on norms and national and international laws, this work aims to the development of a study on the efficacy of micro-wave irradiation in the process of de-vulcanization of tire powder to be used in recycling. Tire powder was subjected to micro-wave irradiation and further merged to SBR (butadiene-styrene rubber) polymeric matrix, at 5, 15, 25 phr; after mixture, resulting compound was characterized for evaluation of physico-chemical and mechanical properties. For the assessment of all samples containing SBR and rubber powder there were applied following essays: Infra-red spectroscopy (FTIR), Tensile strength and elongation at break, Swelling Index. It was verified higher values for mechanical properties imparted by an increased quantity of rubber powder incorporated to SBR matrix.

Butyl rubber has a comprehensive use in sealing systems, especially in tires inner tubes, due to their low permeability to gases.So, it is required that butyl rubber compounds show a better performance, more and more.Butyl rubber is provided with excellent mechanical properties and oxidation resistance.Besides showing these properties, radiation exposures impart modifications in physical-chemical and morphological properties on butyl rubber materials.When exposed to gamma-radiation, rubbers suffer changes in their mechanical and physical properties, caused by material degradation.The major radiation effect in butyl rubbers is chain-scission; besides, ageing promotes too the same effect with further build-up of free radicals.This work aims to the study of gamma-radiation in physical-chemical properties of butyl rubber subjected to thermal ageing.Doses used herein were: 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 KGy.Samples were evaluated before and after ageing according to traditional essays, such as: hardness, tensile strength and elongation at break.From accomplished assessments it is possible to affirm that at doses higher than 50 kGy it was observed a sharp decreasing in butyl rubber physical-chemical properties, before and after exposure to ageing.

Polymers are used in various applications and in different industrial areas providing enormous quantities of wastes in environment.Among diverse components of residues in landfills are polymeric materials, including Polypropylene, which contribute with 20 to 30 % of total volume of solid residues.As polymeric materials are immune to microbial degradation, they remain in soil and in landfills as a semi-permanent residue.Environmental concerning in litter reduction is being directed to renewable polymers development for manufacturing of polymeric foams.Foamed polymers are considered future materials, with a wide range of applications; high density structural foams are specially used in civil construction, in replacement of metals, woods and concrete with a final purpose of reducing materials costs.At present development, it was possible the incorporation of PP/HMSPP polymeric matrix blends with sugarcane bagasse and PHB in structural foams production.Gamma radiation degradation, at 50, 100, 150, 200 and 500 kGy showed effective for biodegradability induction.Irradiated bagasse blends suffered surface erosion, in favor of water uptake and consequently, a higher biodegradation in bulk structure.

This research investigated how gamma-radiation affected PP/HMSPP structural foams filled with biodegradable synthetic polyester PLA in terms of thermal properties, biodegradability and infrared spectrum. Polymers are used in various applications providing enormous quantities of wastes in environment and contributing with 20–30% of total volume of solid residues. Besides, shortage of plastics resins obtained from fossil base is addressing research and development toward alternative materials; environmental concerning in litter reduction is being directed to renewable polymers for manufacturing of polymeric foams. Biodegradable polymers, a new generation of polymers produced from various natural resources, environmentally safe and friendly, can contribute for pollution reduction. PLA (poly(lactic) acid)) was chosen to be blended with PP/HMSPP. Blends thereof were subjected to gamma radiation at 50, 100, 150, 200 and 500 kGy doses. Soil burial test pointed toward a partial biodegradation of irradiated PLA-PP/HMSPP foams; other characterizations involved TG/DTG technique and FTIR assessments.

When butyl rubbers are subjected to high energy radiation, they form easy free radicals that initiate various chemical reactions. These reactions alter the molecular distribution of irradiated rubbers by crosslinking or scission affect their physical and mechanical properties. This work aims to the analysis of effect induced by gamma-exposure on the crosslinking density in butyl rubbers by swelling measurements accomplished before and after irradiation at 25, 50, 100 and 200 kGy, with further evaluation of crosslinking density accomplished by Flory-Rehner equation; this is a proper procedure for the qualification of radiation resistance. It can be noticed that changes in material structure was due to build-up of new three-dimensional network in studied rubbers. Changes in crosslinking density of butyl rubber compounds emphasize that degradation mechanism is strongly influenced by gamma-radiation doses higher than 50 kGy, since chain scission process predominates over crosslinking reaction.

In this paper the modifications induced in butyl rubbers (pristine, chlorinated and brominated sorts) by γ-irradiation are investigated by swelling, chemiluminescence and FT-IR. The susceptibility of butyl rubbers for the generation of radicals orders their stabilities in the following sequence: IIR > IIR—Cl > IIR—Br. The incorporation of butyl rubbers into ethylene-propylene terpolymer matrix brings about increased densities of radicals initiating modifications in the oxidation state in respect with recombination, which are intensified as the processing dose increases. Based on the variation of carbonyl and hydroxyl indices the favorable route for the recycling EPDM based formulations would be suggested in this study. The chemiluminescence spectra proving the formation of peroxyl radicals at about 100 °C prove their availability as reclaiming solutions. IIR—Br is the recommendable butyl rubber for the recovery procedure by association with EPDM. The suitability of IIRs for recycling purposes is analyzed by the variation in their crosslink densities, free volumes and swelling degrees. The crosslinking behavior of stabilized EPDM/IIR blends that runs to the improvement of durability is depicted by Charlesby–Pinner representation, which involves the different simultaneous contribution of scission and crosslinking processes.

Various types of EPDM rubbers are used in radiation areas such as coating materials for wire and electrical cables, due to their higher resistance to environmental effects when compared to other types of rubbers. Properties set for EPDM rubbers that include degradation and good chemical resistance, besides excellent electrical properties have been stimulating the application of this elastomer for low and medium voltage (up to 35 kV). EPDM rubber is classified as radiation-resistant, because EPDM structure includes in its principal chain totally saturated bonds, and consequently is able to absorb more energy without cracking polymeric chain. The purpose of this work was studying radiation influence on rubbers compounds used in wires and electrical cables installed in Nuclear Plants. There were prepared EPDM compounds samples, further subjected to gamma radiation at doses: 25 kGy, 50 kGy, 75 kGy, 100 kGy and 200 kGy. Mechanicals properties and swelling properties were assessed in non-irradiated and irradiated samples at different doses. It was observed a reduction in tensile at break values, proportional to the dose applied and pointing toward a raise in material fragility. This reduction is more severe for doses higher than 100 kGy, indicating the predominance of chain-scission with further polymer degradation.

Polymeric materials (plastics and rubber) have been contributing in a continuously and raising way for the generation of litter and industrial wastes discarded in landfills. The implementation of new technologies for the reduction of polymeric materials, acceptable from the environmental viewpoint and at an effective cost, proved to be a great problem, due to complexities inherent for the re-use, especially of rubbers. Gamma ionizing radiation has capacity for changing structure and properties of polymeric materials and can be applied to almost all types of polymers; irradiation is an expectation for problemsolving of rubber wastes management that can be utilized as raw-materials or chemical additives. Bromobutyl rubber has excellent mechanical properties and oxidation resistance, as well as low gas and water vapor permeability. At the initial stage of irradiation the degradation of Bromobutyl rubber occurs predominantly via random chain-scission and chain-crosslinking may occur caused from the isoprene copolymerized units. The objective of this work is to develop controlled degradation processes (devulcanization) of Bromobutyl rubber and in order to characterize their availability to change and change its properties, such as strength, elongation, hardness, and rheological properties, etc. The experimental results obtained showed that the bromobutyl rubber irradiated to 25 kGy and subsequently sheared can be used as starting point for blending with virgin rubber.

The mitigation of oxidative degradation under γ-irradiation promoted by eight commercial antioxidants: Ethanox 330, Hostanox O3, Irganox 1010, Topanol OC, Ionox 220, Santonox R, Santowhite, Cyanox 2246 loaded onto ethylene-propylene terpolymer at the concentration of 0.5 phr in respect of a pristine polymer was studied. The polymer samples were exposed to various doses up to 500 kGy. The kinetic parameters of oxidations: oxidation induction times, onset oxidation temperature, oxidation rates were evaluated by CL measurements. They validated the differences in the stabilisa-tion activities by limitation of the oxidation gradient. The high efficiency of some of the antioxidants studied, such as Ionox 220 and Santowhite, ensured the delay in degradation even at a high irradiation dose (500 kGy). For the environments with γ-radiation exposure, a relevant sequence in the increasing protection efficiency could be established: Topanol OC; Hostanox O3; Irganox 1010; Cyanox 2246; Santonox R; Ionox 220; Santowhite. The FT-IR spectra were recorded for the calculation of the radiochemical yields resulting from the modifications occuring in the concentrations of oxygenated structures. The accumulations of hydroxyl- and carbonyl-containing products were calculated to evaluate the irradiation effects in EPDM-based products during a severe accident. The options for EPDM stabilisation are discussed based on chemiluminescence and FTIR analyses.

Thermoplastic elastomers (TPEs) are provided with many properties of elastomeric or rubbery materials, but can be processed with the thermoplastic processing methods; they are one of the fastest growing polymers materials which combine the elastic and mechanical properties of crosslinked rubbers with the melt processability of thermoplastics. In addition, TPEs find a lot of applications in automotive, buildings and construction, wires and cables, etc.; besides their ability to reuse and recycle the production scrap and waste. Polypropylene (Pp) is a commodity, with high melting point, high chemical resistance, low density, with a balance between physical and mechanical properties and easy processing at low cost. Nevertheless, Pp shows limitations for some special applications, in terms of impact resistance; in order to minimize this characteristic, an impact modifier, as Ethylene Propylene Diene Terpolymer (Epdm) can be used. Due to different polarity and structure between the thermoplastic and elastomeric phases, most thermoplastic elastomers are incompatible. Poor interfacial adhesion and high interfacial tension between rubber and thermoplastic phases are main reasons for incompatibility of these systems; in case of Pp and Epdm, there is a relatively low interfacial tension (driving force for the transformation of a co-continuous structure into a dispersed one) between Pp and Epdm (approximately 0.3 mN/m), reducing the rate of breakup and facilitating the formation of a continuous structure. Pp/Epdm blends are completely recyclable and reusable, safe to the environment, thus improving the overall profitability of the process. Besides a higher impact resistance shown by Pp/Epdm blends, it is possible that Epdm incorporation in Pp causes a reduction in tensile resistance. In order to eliminate this interference and assuring a more comprehensive application in automotive, buildings and construction, Pp/Epdm blends, rubber contents ranging from zero to 30% (thirty percent), were subjected to gamma-irradiation, within doses from 5 to 20 kGy. Isotactic Pp was considered for this work. Characterization assessments included mechanical, thermal and rheological essays.

Bromobutyl rubber (BIIR) is an isobutylene/isoprene copolymer, containing 1.9% to 2.1% bromine content. Halogenated butyl rubbers have their major applications in tires without inner tubes, various types of seals, membranes, hoses for chemical products conveying and stoppers for pharmaceutical uses. Bromobutyl rubber, when exposed to high radiation energy show two chemical effects: crosslinking and chain-scission with further degradation, prevailing chain-scission. In case there is build-up of insoluble gel, crosslinking will be predominant. Doses used in degradation study via gamma ionizing radiation were: 25 kGy, 50 kGy, 100 kGy, 150 kGy and 200 kGy and there were assessed changes in principal properties. Compounds of bromobutyl rubber showed significant radio degradation above 100 kGy. Doses higher than 100 kGy imparted changes in mechanical properties, due to degradation caused by gamma irradiation.