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The thermomechanical coupling of Mullins damage in filled EPDM has been investigated by analysing the self-heating via Infrared thermography (IR) and the voiding fraction by Digital Image Correlation (DIC). The volumetric strain measured during the rubber deformation is found to be predominantly associated with damage, while thermal dilatation caused by self-heating has a negligible contribution. On this basis, the thermomechanical coupling of Mullins phenomena has been identified by evaluating the strain and time dependence of the following criteria: the tangent modulus, the voiding rate and the heat sources. The tangent modulus that reaches a maximum at the strain transition from a series of cycle to another is found to be an appropriate mechanical signature of Mullin softening. At the same strain transition, both voiding rate upturn and heat source upturn are observed. These signatures suggest the Mullins damage to be mainly associated at high strain rate with the (re)-activation of dissipative cavitation mechanisms, by nucleation of new cavities and/or acceleration of cavities growth.

Application of renewable fuels and changes in fuel composition often create many trouble in gaskets, seals, elastomers and O-rings in the engine fuel system. In a CI engine fuel system, fuel comes in touch with different elastomeric components. The compatibility of automotive fuel system components like seals, gaskets and hose materials using conventional fossil based diesel has long been recognized and documented but there is concern over the use of elastomeric materials with biodiesel. Based on these concerns, a study of compatibility of Natural rubber, Nylon and EPDM (Ethylene Propylene Diene Monomer) with biodiesel and diesel was carried out. High FFA oil, which is a byproduct of edible and non-edible oil refineries, is available at low price and in considerable quantities at vegetable oil refinery sites. In the current study, high FFA oil is synthesized into biodiesel by two step process i.e. esterification followed by transesterification. The methyl ester content of biodiesel is determined by GCMS. The fuel properties of the produced biodiesel were found to be comparable with that of biodiesel specifications. Static immersion test in biodiesel and diesel has been carried out as per SAE J1748 standards. This paper aims to characterize the compatibility of Natural rubber, Nylon and EPDM, commonly encountered in the automotive fuel system in diesel engines. Static immersion test in B100 and diesel fuel was carried out at 55±2 °C (SAE J1748 para 5.2) for 500 hours. Fuels were replaced weekly as suggested in SAE standard. Before the immersion test, mass measurements and visual inspection were recorded. Before and after immersion, comparative behavior was investigated by weight loss, volume change, hardness; tensile strength measurements. Changes in surface morphology were studied by Scanning Electron Microscopy. It was found that natural rubber showed less detrimental effects while significant detrimental effect on EPDM and Nylon was observed.

International audience; This review aims to cover the state of the art of renewable feedstock use in materials production using photopolymerization processes. This area of investigation is an emerging field of research, and it combines biosourced molecules with a cheap and rapid radiative processing method that avoids any emission of volatile organic compounds. The main classes of naturally occurring molecules and macromolecules such as lipids, amino acids, carbohydrates, polyenes, etc. are detailed. The way they are used or integrated in photopolymerizable systems are described in relation to their applications: coatings, biomaterials, biodegradable drug delivery systems, microelectronics or optoelectronics. This critical review takes into account the reactivity of the various compounds as well as their cytotoxicity, biodegradability and finally their end uses.

Nanocomposite materials obtained from natural rubber (NR) reinforced with different amounts of cellulose II nanoparticles (in the range of 0 to 30 phr) are studied by dielectric spectroscopy (DS). For comparative purposes the pure materials, NR and cellulose, are also investigated. The dielectric spectra of the nanocomposites exhibit: (a) two overlappedα-relaxations associated respectively with the dynamic glass transitions ofNR (faster process) and of the lipid present in NR; (b) a β-relaxation associated with local chain dynamics of cellulose and (c) a relaxation process associated to the presence of traces of water in cellulose. The spectra exhibit conductivity phenomena at low frequencies and high temperatures. The samples were also studied in the dry state. An explanation is given concerning the cellulose effect on the dielectric properties of the dry and wet nanocomposites, The authors gratefully acknowledge CICYT for Grant No. MAT2008- 06725-C03-03 and Generalitat Valenciana for Grant No. ACOMP/ 2010/204

A detailed theoretical analysis has been carried out to study the role of ceramic supports (alumina and SiC) and pulsed microwave heating of polymer (Natural Rubber, NR, and Nylon 66) slabs due to various distributions of microwave incidences. Ceramic plates are typical representations as they withstand high temperature without any deformation. It is found that ceramic plates influence the heating processes significantly and local hot spots within samples are governed by specific type of ceramic plates for various sample thicknesses and distributions of microwave incidence (one side or both sides). Optimized pulsing of microwave incidence has been employed to minimize the thermal runaway or hot spots in order to achieve uniform temperature distribution and pulsing is introduced based on two parameters: setpoint ( Δ T S ) and on–off constraint ( T ′ ) . Detailed spatial distributions of power and temperature are illustrated for a few representative length scales to demonstrate the role of local maxima in power and temperature on heating rate as well as thermal runaway with or without pulsing. Pulsing ratio (PR) has been defined as PR = t off / t p , where t off is power-off time and t p is the total processing time such that smaller PR denotes large processing rates. It is found that one side incidence gives smaller values of PR for both the ceramic plates whereas SiC plate may be suitable for both sides incidence with large sample thicknesses of NR samples. It is also found that larger values of setpoints also minimize PR. The setpoints along with the on–off constraint play critical role to select the heating strategy as a function of ceramic plates and types of incidence. Pulsing may not be important for smaller thicknesses of Nylon samples and SiC or alumina plates may be recommended for processing larger thicknesses of Nylon samples in presence of pulsing. Current study recommends the efficient microwave heating methodologies for polymer processing attached with ceramic plates by means of optimized pulsing for the first time.