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The effect of a radiation-initiated polyester on the physicomechanical properties of a sand/clay-polyester composite has been investigated. The unsaturated polyester resins containing various styrene contents were used at different sand/clay composites from 10 to 70 wt % with respect to the weight of sand and clay together; polymerization was conducted using ␥-irradiation at 50 kGy. Also, different particle sizes of clay (namely 1.25-0.80, 0.80 -0.50, and Ͻ0.50) were used. The compressive strength, apparent porosity, and water absorption-in addition to infrared spectroscopy of the composite samples-were studied. Results indicate that the compressive strength decreases with an increase in sand/clay, as well as the styrene content in the unsaturated polyester resin, whereas the apparent porosity and water absorption of the composite samples increase. Infrared spectra showed the appearance of new bands, which indicated a chemical reaction between polyester and clay constituents.

Various types of bonding agents have been tried with blends of bagasse fibers and some thermoplastics such as low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC). These bonding agents are, namely, pentaerythritol tetracrylate (PETA), 1,6 hexandiol diacrylate (HDA), and dicumyl peroxide (DCP). In addition, a traditional coupling agents 3‐aminopropyltrimethoxy silane (AMPS) and di‐aminopropyltrimetoxy silane (DAMPS) were included for comparison. Electron beam (EB) irradiation is applied only for LDPE and HDPE at 40 and 10 kGy, respectively, before mixing with bagasse fibers. The data obtained reveal that incorporation of bonding agents remarkably increases the mechanical properties for all samples under investigation; the maximum improvement is observed in LDPE followed by HDPE, PP, PS, and PVC composites. Also, the physical properties enhanced but not at the same degree as mechanical properties. Among the tested bonding agents, it was found that PETA, DCP followed by DAMPS have highest efficiency in LDPE, whereas in case of HDPE, EB radiation was higher than PETA followed by DCP. PETA was superior in case of PS composites. Furthermore, PETA and HDA experienced higher efficiency than DAMPS and AMPS in case of PP and PVC composites. Comparison between the properties of thermoplastic composites and medium density fiberboard (MDF) reveals that most of the properties of thermoplastics composites are better than MDF. However, modulus of rupture of MDF was found to be slightly higher than thermoplastics except for PVC composite. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers

The influence of thermoplastic/bagasse fiber ratio, as well as electron beam irradiation on the physicomechanical properties of low-density polyethylene (LDPE) and high-density polyethylene (HDPE) composites has been investigated. The concentration of bagasse fibers ranges from 20 to 80 wt%. The results indicate that there is deterioration in the properties as fiber concentration increased; however, it becomes significant only beyond 50% (w/w) bagasse fibers in both LDPE and HDPE composites. Also, the data show that this decrease in the properties is more pronounced in HDPE rather than LDPE composites. It can be noticed that enhancing adhesion between fibers and thermoplastics can be achieved by irradiation of the thermoplastic phase prior to mixing at 10 up to 60 kGy; a maximum improvement in the properties is observed at 40 and 10 kGy for LDPE and HDPE, respectively. From the data it can be seen that the increase in the flexural properties is higher than 100%, while it does not exceed 65% for impact toughness. On the other hand, the reduction in water absorption is not more than 5.5%. Also, examining SEM micrographs reveals that there is some sort of adhesion between fibers and thermoplastics phases.