Structure-property relationship of electron-beam-modified EPDM rubber

This study, uses two polyfunctional monomers (PFMs) namely ethylene glycol dimethacrylate (EGDMA) as a bifunctional monomer and trimethylolpropane triacrylate (TMPTA) as a trifunctional monomer were used as co-agents in irradiation crosslinking of Ethylene Propylene Diene Monomer Rubber (EPDM). The effect of concentration of each PFM and irradiation dose on the crosslinking density, gel content, swelling behavior in motor and brake oils, in addition to the mechanical and thermal stability properties of EPDM was investigated in detailed. The results showed a remarkable increase in the gel content, crosslinking density and mechanical properties as the concentration of PFMs increased from 1 to 5 phr (parts per hundred parts of rubber). The various blends of EPDM with the trifunctional monomer express the highest gel content and crosslinking density than those with the bifunctional monomer. The addition of 5 phr of TMPTA to EPDM causes a dramatic improvement in tensile strength (TS) of the prepared blend reached to 188% compared to neat EPDM at 50 kGy. At the same time, the maximum TS of the blend containing 5 phr of EGDMA achieved only 41% compared to neat EPDM at an irradiation dose of 100 kGy. The swelling of irradiated samples in brake oil revealed a stronger oil resistance than motor oil. For all irradiated samples, the oil uptake decreased with the irradiation dose up to 100 kGy. The EPDM samples containing 5 phr of TMPTA recorded the highest oil resistance at 100 kGy. The results also showed that the addition of PFMs and irradiation treatment of the various prepared blends improved the thermal stability of EPDM. Finally, neat EPDM and the blends containing 1 and 3 phr of EGDMA can be used as radiation dosimeters in the very high dose range (50–200 kGy).

EPDM rubber was surface- and bulk-modified with varying concentrations of trimethylol propane triacrylate (TMPTA) in the presence of a constant electron-beam irradiation dose of 100 kGy and over a wide range of irradiation doses from 0 to 200 kGy at a fixed TMPTA concentration (10%). The permeation rate and absorption of three homologous nonpolar solvents, namely, n-hexane, n-heptane, and n-octane, along with an aromatic solvent, toluene, and a polar solvent, trichloroethylene, through unirradiated, unmodified control, and modified rubber membranes (≈150 μm) were studied. It was found that both the permeation rate and absorption decrease progressively with increase in the TMPTA concentration up to 10% for both the surface- and bulk-modified rubbers. With increase in the radiation dose, there also is an initial drop in the values up to 50 kGy for the control and surface-modified rubbers and up to about 100 kGy for the bulk-modified one. The control rubber shows the highest absorption and permeation for all the solvents except trichloroethylene, followed by the bulk-modified rubber membrane. Trichloroethylene is, however, absorbed and permeated most by the surface-modified sample. The observations are explained in terms of the structural modifications of the rubber, crosslinking, changes in the relevant thermodynamic properties such as surface energy, the penetrant size, and the transport mechanism of the penetrants. The influence of temperature on the permeability characteristics of the control and modified rubbers was also studied. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 784–795, 2000

Composites from ethylene propylene diene monomer (EPDM) rubber filled with different concentrations 20, 40, and 60 parts per hundred rubber (phr) of aluminum oxide (Al2O3) were prepared. The samples were vulcanized by gamma irradiation at doses (50,100, 150, and 200) kGy. The effects of irradiation doses and Al2O3 contents on the mechanical prorerties (particularly tensile strength, elongation at break % and hardness), physical properties (volume fraction and crosslinking density), thermal properties was studied by thermogravimetric analysis (TGA) and fire resistance was tested using Limiting Oxygen Index (LOI) and rate of burning methods of EPDM and its composites were studied. The results indicated that the improvement of mechanical as well as, physical properties occurred by increasing the concentration of Al2O3 (except the tensile strength values, where the highest values were obtained at concentration 20 phr Al2O3 in the composite irradiated at 100 kGy). The thermal stability and fire retardancy properties of the prepared composites were improved by increasing Al2O3 concentration. Generally, the addition of Al2O3 and gamma irradiation has improved composite’s performance. This is suitable for preparing products of rubber serving in dynamic conditions, with longer expected service life

Magnetic composites were manufactured by incorporating 5 phr of Carbonyl Iron Powder (CIP) and 60 phr of carbon black into ethylene propylene diene monomer (EPDM). This study aimed to examine the impact of different curing systems - sulfur and accelerators, peroxide, and peroxide with co-agents - on the cross-linking of the EPDM matrix while keeping other additives constant. Seven composites were produced and characterized in terms of morphology, cross-link density, rheometric, mechanical, and magnetic properties. The sulfur curing system reduced curing time and increased cross-link density, resulting in higher rigidity. The peroxide-based system, when combined with co-agents, provided optimal performance in elongation and tear strength, with tensile strength values similar to the sulfur system. Cross-link density was highest for the sulfur and accelerator systems, and the Gibbs free energy was higher due to reduced molecular mobility in highly cross-linked networks. The 5 phr CIP content did not affect the physical-mechanical properties. Scanning Electron Microscopy (SEM) revealed minimal interaction between EPDM and CIP, and magnetic analysis showed that the curing system had no significant impact on the magnetic properties of the composites.

Influence of radiation temperature on the crosslinking of nitrile rubber by electron beam irradiation

The goal of this research is to evaluate the recovered chitosan from locally discarded shrimp shells for usage as a biofiller for ethylene propylene diene monomer (EPDM) rubber in green chemistry industries. The utilization of two distinct fillers are expected to improve the qualities of industrial applications while lowering the cost. A laboratory two-roll mill, was used to prepare the rubber nanocomposites by incorporating nano fumed silica and chitosan as biomaterials into the EPDM rubber matrix. The mechanical and morphology characteristics of the produced EPDM rubber were investigated. The rubber nanocomposites were exposed to gamma irradiation doses ranging from 20 to 150 kGy. The tensile strength (TS) of the EPDM/chitosan/fumed silica vulcanizate increased when the chitosan concentration was raised up to 5 phr, but the elongation at break was reduced. However, the use of fumed silica as binary filler with chitosan improved the mechanical performance and thermal stability. The influence of gamma irradiation on the mechanical properties was also explored. The antimicrobial activity of the EPDM nanocomposites agaist Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria was investigated in terms of the zone of inhibition. The results indicated that the nanocomposites irradiated to 100 kGy and containing 10 phr fumed silica and 5 phr chitosan exhibited the highest mechanical, thermal, and antibacterial characteristics and might be used in a variety of applications such as packaging material and surface application/coating based for different devices

Abstractγ‐irradiation of ethylene–propylene diene monomer (EPDM) elastomers under oxidant atmosphere was carried out in order to change their mechanical and dielectric behaviour. Three different formulations of EPDM (70 wt% ethylene, 28 wt% propylene; diene monomer: 2 wt% norbornene) were studied: a non‐crosslinked EPDM terpolymer, a crosslinked EPDM and a crosslinked EPDM stabilized with an antioxidant. Dielectric and mechanical relaxation show a β‐sub‐glass relaxation at about −120 °C (1 Hz) and an α‐relaxation at −15 °C (1 Hz) associated with the glass transition but influenced by the effects of irradiation. The local mobility associated with the β‐relaxation is only weakly influenced by γ‐irradiation up to 450 kGy. The α‐process is shifted to higher temperatures as a result of crosslinking and changes in the semicrystalline structure. The amplitude of the dielectric α‐process increases as a result of the formation of oxidized species during irradiation under oxygen. In contrast, the mechanical α‐relaxation amplitude decreases as a result of physical and chemical cross‐linking. It was shown that the main factors that determine the crosslinking/chain scission balance are (1) the presence of oxygen together with the irradiation dose, (2) the dose rate and (3) the initial crosslink density of the EPDM material. As a result, the individual contribution of crosslinking and crystallization, and therefore the understanding and prediction of the properties after γ‐irradiation can only be deduced after comparison of the polymer behaviour below and above its melting temperature. Copyright © 2004 Society of Chemical Industry

Photo-DSC and dynamic mechanical studies on UV curable compositions containing diacrylate of ricinoleic acid amide derived from castor oil

ABSTRACTThe escalating demand for efficient and sustainable carbon capture and storage technologies requires robust materials capable of withstanding the challenging temperature and pressure conditions encountered in CO2 transport systems. To address this need, this research investigates the suitability of ethylene propylene diene monomer (EPDM) elastomers as potential materials for carbon dioxide (CO2) transport systems, such as seals and gaskets. This research presents a detailed characterization of the effect of varying degrees of crosslink density and carbon black content. Insights into CO2 uptake and reduction in glass transition temperature (Tg) following exposure to liquid carbon dioxide (LCO2) are presented. The work also focuses on the investigation of CO2 permeability, diffusivity, and solubility in EPDM using a constant volume and variable pressure method at different temperature and pressure conditions. The work extends to the extraction of EPDM using various solvents that are liquid at ambient conditions, examining their subsequent changes in thermal, mechanical, and CO2 transport properties.

The waste newsprint paperswere collected from local market and submitted to chemical pulping in a kneader with 2M NaOH. The fiber after getting rid of water, treated again using 2M HCL solution for the same time period. Then the news print pulped microfibers (NPMF) batch obtained was mixed with Ethylene propylene diene monomer rubber (EPDM) on roll mill with differnet contents ranged from 5 to 50phr (part per hundred part of rubber). The prepared composites subjected to gamma irradiation at different doses from 20 up to 100kGy. The characterization of the microfibers carried out by different tools like scanning electron microscopy (SEM), X-ray diffraction (XRD),Forrier Transform Infrared spectra (FTIR) and Thermogravimetric analysis (TGA). The mechanical properties of prepared composites like tensile strength (Ts), Elongation at break (Eb%), tensile modulus(M100) , tensile toughness and crosslink density (Cd) were measured as a function of fiber contents and irrdaition dose. The results indicated the Ts was increased with increasing fiber content up to 10phr and incresed with increasing irradiation dose up to 40kGy, while Eb% decreased by fiber content and irradiation dose. M100 and Cd were incresed with invreasing fiber content up 50phr fiber and increased by irradiation dose up to 60kGy. The results concluded that toughness values of EPDM/ news print fiber composite reach maximum using 10phr fiber concentration and 60kGy irradiation dose.

In an attempt to maximize the beneficial effect of irradiation, the influence of multifunctional acrylates (MFAs) such as trimethylol propane triacrylate, ethylene glycol dimethacrylate, trimethylol propane trimethacrylate, and tripropylene glycol diacrylate on the 90/10 ethylene vinyl acetate/waste tire dust (EVA/WTD) were studied. The 90/10 EVA/WTD and EVA-containing 4 phr MFA prepared using a Haake mixer at 140°C and 50 r min−1 rotor speed. The blends were then irradiated using a 3.0-MeV electron beam machine. Results on gel fraction revealed that EVA/WTD blends were cross-linked by electron beam irradiation. Among the MFA employed in this studies, TPGDA was found to render highest tensile strength with the best retention in elongation at break and increased heat of fusion and crystallinity of blends upon irradiation. The changes in the properties of EVA/WTD blends upon irradiation are attributed to the cross-linking of the EVA matrix. The changes in crystallinity and crystalline melting temperatures of EVA/WTD blends upon irradiation are discussed in detail.

Rubber magnetic composites were fabricated by incorporation of strontium ferrite in constant loading level in ethylene propylene diene monomer rubber and acrylonitrile butadiene rubber. Different curing additives based on peroxide, sulfur and combined sulfur/peroxide systems were introduced for cross-linking of rubber matrices. Both sulfur and peroxide curing systems lead to the formation of cross-links with different length and structure, which subsequently results in different properties of rubber products. Moreover, due to various bonding energies of the formed cross-links, rubber articles exhibit different propensity to degradation factors as to thermo-oxidative aging. Therefore, the work was aimed at the investigation of curing system composition and aging on cross-link density and properties of rubber magnetic composites. The achieved results point out to close correlation between cross-link density and physical-mechanical characteristics with exception of tensile strength, which showed increasing tendency with increasing amount of peroxide in combined vulcanization systems. It can be stated that no significant changes in physical-mechanical and magnetic properties were recorded during aging.

Ethylene propylene diene monomer (EPDM) rubber/zinc dimethacrylate (ZDMA)-samarium methacrylate (Sm(MA)3) rare earth complex as seals were prepared via in-situ formation of Sm(MA)3 to partially replace the ZDMA. Compared with neat EPDM, incorporation of ZDMA-Sm(MA)3 improved the curing activity of EPDM and a multiple crosslinking network formed with high crosslinking density. Improvement of the interfacial interaction facilitated distribution of the ZDMA-Sm(MA)3 in the matrix and resulted in an increase of the mechanical properties of the composites compared with neat EPDM. In addition, partially replacing the ZDMA with Sm(MA)3 significantly enhanced the durable sealing resilience performance of the composites by improving their free radical scavenging ability and inhibiting the degradation, oxidation and crosslinking reaction of the EPDM during stress-thermal oxidation aging.

Herein, we describe the preparation of patterned photoresponsive hydrogels by using a facile method. This polymer-network hydrogel coating consists of N-isopropylacrylamide (NIPAAM), cross-linking agent tripropylene glycol diacrylate (TPGDA), and a new photochromic spiropyran monoacrylate. In a pre-study, a linear NIPAAM copolymer (without TPGDA) that contained the spiropyran dye was synthesised, which showed relatively fast photoswitching behaviour. Subsequently, the photopolymerisation of a similar monomer mixture that included TPGDA afforded freestanding hydrogel polymer networks. The light-induced isomerisation of protonated merocyanine into neutral spiropyran under slightly acidic conditions resulted in macroscopic changes in the hydrophilicity of the entire polymer film, that is, shrinkage of the hydrogel. The degree of shrinkage could be controlled by changing the chemical composition of the acrylate mixture. After these pre-studies, a hydrogel film with spatially modulated cross-link density was fabricated through polymerisation-induced diffusion, by using a patterned photomask. The resulting smooth patterned hydrogel coating swelled in slightly acidic media and the swelling was higher in the regions with lower cross-linking densities, thus yielding a corrugated surface. Upon exposure to visible light, the surface topography flattened again, thus showing that a hydrogel coating could be created, the topography of which could be controlled by light irradiation.

Radiation processed polychloroprene–co-ethylene-propene diene terpolymer blends: Effect of radiation vulcanization on solvent transport kinetics