Search results for " Rubber"

Regarding the influence of the particle size of crumb rubber from waste rubber on the physical and mechanical characteristics of reclaimed rubber

2017

Thus, at present, a large amount of rubber waste cannot be higher harnessed due to recovery technologies used. Also, the requirements for new products of rubber worldwide are greater than the production capacity and the availability of raw materials. To offset this balance is necessary to improve technologies for recycling waste rubber so to can get regenerated rubber with the best mechanical physical characteristics. The main technology for obtaining the regenerated rubber is based on the rubber waste shredding and making the powder, so that it can be carried out de-vulcanization in autoclave. All the time it was monitored as the de-vulcanization process to be as economical and less pollut…

Procedure for a Temperature-Traffic Model on Rubberized Asphalt Layers for Roads and Railways

2017

The impact of temperature on the mechanical properties and thermal susceptibility of the railway bituminous sub-ballast layer, has served as motivation to develop the advanced measurement of thermal cycles in this layer and, an evaluation of the average seasonal temperatures interpolated by sinusoidal functions, of which characteristic parameters are determined. According to weather situation, Barber’s temperature model was used to prove the effectiveness for the railway superstructure. It is included the assessment of improved modified asphalt mixes performed with coarse rubber from scrap tires, having 1.5 to 3 percent of crumb rubber (particle size 0.2-4 mm) by weight of the total mix, as…

Latex allergy: the sum quantity of four major allergens shows the allergenic potential of medical gloves

2007

Background:  Assessment of allergenic potential of medical devices made of natural rubber latex (NRL) requires the measurement of concentrations of specific allergenic proteins or polypeptides eluting from rubber. Methods:  Four NRL allergens (Hev b 1, 3, 5, and 6.02) were quantified in all medical glove brands marketed in Finland in 1999, 2001, and 2003 (n = 208) by a capture enzyme immunoassay. The results were compared with those obtained from previous nationwide market surveys, using a skin prick test-validated human IgE-based ELISA-inhibition method. Results:  A high overall correlation (r = 0.87, 95% CI 0.83–0.90) emerged between the sum values of the four allergens(μg/g glove) and Ig…

Are we correctly measuring the rotational viscosity of heterogeneous bituminous binders?

2020

Modified bituminous binders allow asphalt technologists to design asphalt mixtures with superior performance. However, several recent studies highlighted that due to the complexity of these material, their characterisation can be challenging since common procedures used to characterise neat bitumen might not be adequate. For instance, during high temperature rotational viscosity testing of recycled tyre rubber modified binders (RTR-MB), a number of changes may occur to the sample leading to the here-defined sample stability which in turn provides misleading results. In this study the authors want to first provide a deeper understanding of this phenomenon by a numerical analysis using a besp…

An investigation of the mechanical properties of rubber modified asphalt mixtures using a modified dry process

2017

Incorporating recycling tyres into asphalt mixtures contributes to solving a serious environmental problem as well as the potential of improving the mechanical performance of asphalt mixtures. The recycled tyre rubber is added by two technologies known as the dry process (when rubber particles are treated as an aggregate modifier) and the wet process (when rubber particles are treated as a binder modifier). Although, the dry process is easier and requires minimal or no modification in the asphalt plant, the inconsistency in field performance makes the dry process not widely used. The main reason for this is believed to be the lack of interaction between the rubber particles and binder. In o…

Latex allergy in dentistry: clinical cases report

2010

Generally natural rubber latex (NRL) allergy is detected after some exposition to the material. As NRL is com- monly found in different materials used daily in dental clinic, the allergy can be manifested in the pediatric dentistry clinic. The first clinical manifestation can be smooth but also severe, therefore it is important to know different manifestations and how to prevent them. Objective: Report two clinical cases of natural rubber latex allergy in children and to present the safety measures that must be taken during clinical assistance, as using metallic saliva ejector, vinyl gloves for the treatment procedures and as an option to rubber dam. Cases Report: Case 1- Patient presented …

1992

Semi-IPN's of different composition, based on linear poly(methyl vinyl ether) (PVME) and crosslinked polystyrene are studied using stress and birefringence measurements in simple elongation. From quasistatic stress-strain experiments at constant T(experiment)-Tg, it can be deduced that the stress results only from the deformation of the polystyrene network, while the PVME chains do not contribute to the macroscopic stress. The concentration dependence of the network modulus is adequately described by the rubber elastic theories

A comparative life-cycle assessment of asphalt mixtures for railway sub-ballast containing alternative materials

2018

Abstract Bituminous sub-ballast in railway track-bed can mitigate the variation of the moisture content in the subgrade and reduce vertical stiffness variations of the track leading to a more durable infrastructure. Nevertheless, durability is only one of the aspects that affects the sustainability of an infrastructure. Other relevant aspects are related to the environmental and economic issues. This research work joins the worldwide effort towards a paradigm shift in civil engineering devoted to assess the sustainability of infrastructures at the design stage. With this in mind, in this study different alternative bituminous sub-ballast mixtures containing recycled materials, namely crumb …

Polydimethylsiloxane (silicone rubber) brooch as a personal passive air sampler for semi-volatile organic compounds

2018

Exposure assessments conducted using a personal sampler include the contribution of human activities to exposure that is neglected when using a stationary air sampler. This study evaluated the uptake characteristics and application of the polydimethylsiloxane (PDMS or silicone rubber) brooch as a personal passive air sampler (PPAS) for measuring concentrations of two groups of semi-volatile organic compounds (SVOCs), namely phthalates and organophosphate esters (OPEs), indoors in proximity to the breathing zone. Uptake rates of the PDMS brooch were calibrated against a personal low volume active air sampler (PLV-AAS) co-deployed on each of five study participants working in offices for 8 hs…

Size, Form and Flexibility of the Rubber Molecule

1962

Abstract Natural rubber can be brominated in dilute cyclohexane solution, whereby the molecular weight, corresponding to the bromine content, increases. For brominated rubber, increasing bromine content makes cyclohexane an increasingly poorer solvent, which is shown by a contraction of the molecule coils and a decrease in the second virial coefficient. Quantitative results were obtained through viscosity and light scattering measurements. Cyclohexane solutions of brominated rubber containing about 43% bromine have a θ point at room temperature. Here the second virial coefficient is zero and the coil has an ideal Gaussian density distribution. In this state the coil diameter is about 1.6 ti…