Khaled F. El-Nemr

Waste newsprint fibers for reinforcement of radiation-cured styrene butadiene rubber-based composites - Part I: Mechanical and physical properties

In this study, waste newsprint paper fiber was treated by polystyrene emulsion and included as a filler in styrene butadiene rubber. Then, the composites were subjected to electron beam irradiation at different irradiation doses, and follow-up was done on the effect of irradiation dose and fiber concentration on mechanical and physical properties of prepared composites. The results indicated that the mechanical properties like tensile strength, elongation at break, stiffness, and toughness were enhanced by the increase of radiation and fiber content. Also, the physical properties like soluble fraction, swelling ratio, and volume fraction of rubber in swollen gel were enhanced by the increase of radiation and fiber content. On the other hand, scanning electron microscope (SEM) results confirmed that adhesion was situated between fiber and rubber matrix.

Effect of ionizing radiation on the properties of acrylonitrile butadiene rubber/clay nanocomposites:

The effects of electron beam irradiation dose (50–150 kGy) and the concentration of montmorillonite (MMT) clay (3–10 parts per hundred part of rubber (phr)) on the properties of acrylonitrile butadiene rubber (NBR) have been investigated. The dispersion of the layered silicates was assessed by x-ray diffraction and transmission electron microscopy. The morphology of NBR nanocomposites showed exfoliated clay layers at low clay content and a combination of exfoliated and intercalated clay layers at high clay content. The mechanical properties of NBR composites such as tensile strength (TS) and tear strength were remarkably improved by the incorporation of organoclay and electron beam irradiation, while elongation at break (E b) was decreased. The increase in the TS of NBR nanocomposites increases with the increase in the clay content up to 10 phr, whereas the optimum gel content and TS of NBR composites were observed at 50 kGy irradiation dose. Thermogravimetric analysis studies showed that NBR/organo-MMT nanocomposites have higher decomposition temperatures in comparison with the NBR/Na+-MMT at 50 kGy irradiation dose.

Sorbic acid as friendly curing agent for enhanced properties of ethylene propylene diene monomer rubber using gamma radiation

ABSTRACT Sorbic acid (SA) is available in the market for low-cost and eco-friendly. It is known for using as a preservative. SA was used as a modifier together with gamma radiation to improve the properties of ethylene propylene diene monomer rubber (EPDM). The effect of SA concentration and gamma irradiation dose on the mechanical and physico-chemical properties of EPDM was investigated. The results indicated that the properties of EPDM rubber blended with SA were improved compared to untreated EPDM sample. The highest improvement was achieved by using SA concentrations of 10 phr (part per hundred part of rubber) a dose of 100 kGy of gamma irradiation. These findings were demonstrated by scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA).

Effect of gamma radiation on physico-mechanical properties of vulcanized natural rubber/carbon fiber composites:

Natural rubber was reinforced with a short carbon fibers (SCFs) at different concentrations (0–20 part per hundred part of rubber (phr)). The composites were vulcanized by sulfur, then subjected to gamma radiation at different doses up to 40 kGy. Physico-mechanical properties of composites were studied. Also, thermogravimetric analysis was used to investigate the influence of the incorporation of SCF on the thermal properties of prepared composites. It was observed that the mechanical properties like tensile strength increases with increasing irradiation dose up to 30 kGy and fiber loading up to 15 phr, meanwhile the hardness and modulus increase with increasing fiber loading, but not affected by irradiation dose. Thermal stability of composites was increased by fiber loading content at constant irradiation dose. The morphological studies were made by means of scanning electron microscopy to investigate the structure change caused by the incorporation of SCF.

Thermoplastic elastomers based on waste rubber and expanded polystyrene: Role of devulcanization and ionizing radiation

ABSTRACT Waste rubber (WR) powder as a vulcanized one was introduced into a two-roll mill in the presence of various ratios of curatives to develop sheets of devulcanized waste rubber (DWR). Thermoplastic elastomers (TPE) were prepared by blending either WR or the obtained DWR with the waste of expanded polystyrene (EPS) at a fixed ratio of 70 rubber/30 EPS in the absence or presence of gamma irradiation at 100 kGy. Maleic anhydride (MA) 1 wt% with respect to rubber was used as coupling agent. The mechanical parameters of the blends: tensile properties, rheology, hardness (Shore D), and abrasion resistance were studied.