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BACKGROUND: Several physical factors such as photon beam energy, electron beam energy, and dose rate may affect the dosimetric properties of polymer gel dosimeters. The photon beam energy and dose rate dependence of PASSAG gel dosimeter were previously evaluated. OBJECTIVE: This study aims to assess the dosimetric properties of the optimized PASSAG gel samples in various electron beam energies. METHODS: The optimized PASSAG gel samples are first fabricated and irradiated to various electron energies (5, 7, 10 and 12 MeV). Then, the response (R 2) and sensitivity of gel samples are analyzed by magnetic resonance imaging technique at a dose range of 0 to 10 Gy, scanning room temperature range of 15 to 22 °C, and post-irradiation time range of 1 to 30 days. RESULTS: The R 2-dose response and sensitivity of gel samples do not change under the evaluated electron beam energies (the differences are less than 5%). Furthermore, a dose resolution range of 11 to 38 cGy is obtained for the gel samples irradiated to different electron beam energies. Moreover, the findings show that the R 2-dose response and sensitivity dependence of gel samples on electron beam energy varies over different scanning room temperatures and post-irradiation times. CONCLUSION: The dosimetric assessment of the optimized PASSAG gel samples provides the promising data for this dosimeter during electron beam radiotherapy.

This paper aims to describe the thermal, mechanical, and surface properties of a PVA/HPP blend whereby the film was prepared using a solution casting method. The improvements in thermal and mechanical properties of HPP-based PVA composites were investigated. The characterization of pure PVA and PVA composite films included tensile tests, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results of TGA and DSC indicated that the addition of HPP increased the thermal decomposition temperature of the composites. Mechanical properties are significantly improved in PVA/HPP composites. The thermal stability of the PVA composite increased with the increase of HPP filler content. The tensile strength increased from 15.74 ± 0.72 MPa to 27.54 ± 0.45 MPa and the Young’s modulus increased from 282.51 ± 20.56 MPa to 988.69 ± 42.64 MPa for the 12 wt% HPP doped sample. Dynamic mechanical analysis (DMA) revealed that at elevated temperatures, enhanced mechanical properties because of the presence of HPP was even more noticeable. Morphological observations displayed no signs of agglomeration of HPP fillers even in composites with high HPP loading.

Polyvinyl alcohol (PVA) composite films with different hemp protein particles (HPP) as additives were successfully synthesized by a solution casting method. The properties of HPP-based PVA composites films were investigated. The characterizations of pure PVA and PVA composite films were performed regarding Fourier transform infrared spectroscopy (FTIR), ultra-violet (UV-Vis) to investigate the chemical properties. The formation of hydrogen bond in the PVA-HPP films, which could improve the compatibility of the two components was investigated by FTIR spectroscopy and UV-Vis analysis. The overall results showed that a higher loading of HPP into the PVA matrix improved the chemical interactions significantly. The swelling degree decreased while the water contact angle values increased as the HPP content increased.

The improvements of the thermal, mechanical, morphological properties of low-density polyethylene (LDPE)/nanoclay (NC) composites were investigated. Low-density polyethylene (LDPE) with different NC contents 2 wt.% ( Vf= 8%), 4 wt.% ( Vf= 15), and 8 wt.% ( Vf= 27) with a fixed particle size (300μm) were prepared by the melt mixing process. The thermal tests (thermal gravimetric analysis) were performed to monitor the thermal stability of LDPE composites. The mechanical tests such as tensile strength, Young’s modulus, and strain at break were studied. The results of the thermal gravimetric analysis (TGA) display significant enhancement in thermal stability as the loading of NC increased in pure LDPE. The results showed that the NC fillers could effectively improve the mechanical properties of LDPE by comparison to pure LDPE, the tensile strength of LDPE/8 wt.% of NC are increasing by about 17% while Young’s modulus is increased by about 39%. From DMA results, the storage modulus is enhanced with increasing of NC loading into the LDPE matrix. The results of SEM photographs indicate that the incorporation 8 wt.% of NC displayed the best particles dispersion in the LDPE matrix.

This article aims to study recycled biochar (R-BCH) improvements on the high-density polyethylene (HDPE) matrix properties. A series of composites was developed with a different loading varying from 0 to 10 wt.% of R-BCH, using a twin-screw extruder followed by compression molding. The results were showed that the addition of 3-10% of R-BCH in pure HDPE led to an increase in the tensile strength, modulus of elasticity, and a decrease of elongation at break. Furthermore, the differential scanning calorimetry analysis (DSC) results showed that incorporating R-BCH into pure HDPE improved thermal properties because interfaces between R-BCH and pure HDPE caused decreased brittle behaviour and enhanced the high crosslinking of pure HDPE.

The effects of UV irradiation on chemical, thermal, mechanical, and morphological properties of polyvinyl alcohol (PVOH)/2 wt.% of nanoclay(NC) filler were investigated. PVOH composite films were prepared from PVOH blend with fixed content (2%) of NC via the solution casting method. Pure PVOH and PVOH composites were exposed to 340 nm fluorescent UV lamps and assessed for 50 h, 100 h, and 200 h UV exposue. The experimental results such as Fourier transform infrared (FTIR) confirmed that 2% wt. NC filler is efficient and can resist chemical degradation that is caused by ultraviolet irradiation (UV). The carbonyl and hydroxyl indices were increased with increasing the UV exposure irradiation times of both PVOH and PVOH composite. However, the PVOH nanocomposites exhibited more resistant to increasing the indices after exposure to UV irradiation with a longer exposure time. The thermal results (TGA) indicated that PVOH nanocomposite is exhibited more resistance to thermal degradation after UV irradiation exposure compared to that of pure PVOH sample. From DMA results, the storage of modulus was reduced after exposure to UV irradiation of PVOH and PVOH nanocomposites. The results of Tg of PVOH nanocomposites increased after the incorporation of 2% wt. NC into PVOH after exposure to UV irradiation. PVOH nanocomposite exhibited more resistance to reduce the tensile strength after exposure to 200 h UV irradiation. XRD tests showed that PVOH/2 wt.% NC nanocomposites have more resistant to increase intensity after exposure to 200 h UV irradiation compared to that of PVOH sample. The morphology micrographs showed that no obvious cracks on the PVOH nanocomposite after UV irradiation exposure by comparing to that of pure PVOH.

Polypropylene (PP)-Nano silica composites have been modified. PP was filled with three different loads of 5, 7 and 10 wt% of nano-silica. Polypropylene/nanosilica composites were prepared via melt extrusion. The results of FTIR spectra of PP and PP nanocomposites exhibited a great chemical interaction between the PP and nanosilica layers and the XRD patterns showed lower intensity and shifted to higher angles of PP/nanosilica composites. The results were identified by Thermogravimetric analysis (TGA), Differential Scanning Calorimeter (DSC), tensile tests, and water absorption tests. From the results of TGA , significant improvements in the thermal stability were noticed with an increase in the percentage of nanosilica particles. The mechanical properties (tensile strength, elastic of modulus and strain at breaks) were improved by increasing loads of nanosilica (10 wt%).

Epoxy-timber composites have received increasing attention during the last decades because there are many advantages related to their uses as construction materials in applications such as timber b...

Accelerated weathering studies are necessary to determine future risks arising from the loss of durability of materials under environmental conditions (e.g. ultraviolet irradiation from the...

This work aims to study the characterizations and modifications of systems based on polypropylene (PP) and nanoclay (NC). In this context, the effects of thermal and mechanical properties of the compsites of nanoclays with different loading of 1, 3, and 6% incorporated in PP matrix were investigated. The influences of thermal and mechanical properties on the preparation of polypropylene/nanoclay (PPNC) composite were investigated. The results of the thermogravimetric analysis (TGA) showed that thermal stability increased with higher loadings of nanoclay. The tensile properties of PP and PPNC were also studied. The tensile strength of PP with the higher loading of nanoclay increased by 24.40% compared to that of the pure PP matrix (27.5MPa). The modulus of elasticity of PPNC with higher loading of 6% NC was higher by 17.32% than that of pure PP. The elongation at break of PPNC reduced by 53%, by comparing with pure PP. The Tg of PNCC with higher loading of NC were higher by 8.6%. The degree of crystallinity of PPNC was higher by 27% than pure PP.

The influence of exposure to UV light and moisture on the durability of a multiwalled carbon nanotube(MWCNT)/epoxy nanocomposite was investigated. Samples of epoxy resin based on diglycidyl ether of bisphenol A (DGEBA) cured with 2,2,4-trimethylene-1,6-hexadiamine (TMDA), and epoxy nanocomposite containing 0.5% MWCNT were exposed to different accelerated weathering times between one and six months. Changes in surface chemistry, mechanical properties (tensile tests), thermal properties (thermogravimetric analysis and differential scanning calorimetry), and morphology were evaluated before and after exposure to accelerated weathering for a period of up to six months. Epoxy nanocomposite (DGEBA–TMDA/0.5%MWCNT) samples had improved thermal stability and resistance to degradation, compared to epoxy resin (DGEBA–TMDA). The effect of MWCNT at reducing degradation was more pronounced than previously found for resins prepared with hydrogenated DGEBA.

Accelerated weathering of polyvinyl alcohol (PVA) and PVA reinforced with 20 wt% of zinc chloride (ZnCl2) was investigated. The developed PVA composites were subjected to 100, 200, and 300 h of accelerated weathering exposure times. The effects of exposure on the PVA composites were characterized by Fourier transform infrared (FTIR), thermal properties as thermogravimetric analysis and differential scanning calorimetry, the mechanical and morphology properties, and X-ray diffraction analysis. The results of FTIR displayed that lower carbonyl and hydroxyl indexes are due to PVA composite. The results of mechanical tests showed that the accelerated weathering reduced the tensile strength of PVA. However, PVA composites exhibited fewer reduction of the tensile strength values. PVA composites exhibited better thermal stability after extent to ultraviolet irradiation. The storage modulus from dynamic mechanical analysis results that displayed a higher value for the storage modulus is related to PVA composites, compared to PVA. Before exposure, PVA composite showed a high intensity, compared to PVA. After exposure to accelerated weathering, the intensity of all samples shifted and decreased. Scanning electron microscopic micrographs showed that the surface of the PVA composites had fewer defects compared to the PVA after exposure. The results of characterization revealed that 20% of ZnCl2 into the PVA made less vulnerable to environmental degradation, and these PVA composites are suitable as packaging films for use in outdoor applications.

The influence of weathering processes on the properties of a multi-walled carbon nanotube (MWCNT)/epoxy nanocomposite was investigated. All the samples, based on the hydrogenated gylcidyl ether of bisphenol A (HDGEBA) with and without 0.5% MWCNT, were exposed to UV radiation and elevated temperature and humidity for extended periods of time: 1, 2, 3, 4 and 6 months. The investigation included the measurement of the effects of accelerated weathering on the surface of samples for long-term conditions and for different exposure times. Chemical changes that occurred on the surface were determined using FTIR. The carbonyl and hydroxyl indexes of the nanocomposite increased much less over time than the epoxy alone, the nanocomposite also showed less loss in tensile strength and modulus and elongation on accelerated weathering, and there were few morphological changes on the composite surface compared to the unmodified epoxy. Glass transition temperatures and temperature of onset of degradation in thermal analysis decreased after accelerated weathering for all samples, but to a much greater extent for the unmodified epoxy. It appears that the incorporation of functionalized MWCNT as a modified inhibitor against accelerated weathering in the epoxy-amine system can decrease the undesirable effects arising from exposure to UV light and moisture exposure.

Natural fibre–reinforced epoxy composites have been increasingly utilised in construction and building applications. These materials introduce cost-effective alternatives to conventional materials and their utilisation often has related to financial advantages that are immediate and can be expected over the structure service life. In this work, the results of thermal, dynamic-mechanical, and thermal-mechanical properties of date palm fibre (DPF)/bamboo fibre (BF) hybrid composite were compared to bamboo fibre-reinforced epoxy to demonstrate the importance of hybridization. The thermal stability was improved when DPF/BF fillers were added in epoxy resin comparatively to BF reinforced epoxy. The glass transition temperature (Tg ) was increased by incorporating the date palm fibre/bamboo hybrid composite in epoxy compared to the BF reinforced epoxy. The thermal expansion was enhanced by modifying the hybrid composites in epoxy in contrast to the single fibre composites, without hybridisation. Hence, the hybridisation technique of date palm fibre with bamboo has improved the thermal and thermal-mechanical properties suitable for several applications including non-structural applications.

A research paper focuses on investigations of the improvements on chemical and thermal, andmechanical properties of polypropylene (PP) by adding cellulose microcrystalline fillers (CMC).The CMC powder was used as reinforcement in pure PP with various weight percentages 5, 10and 20 % respectively. The melt mixing process was used to prepare (PP/ CMC) composites. Thestructural changes of PP/CMC composites were investigated by Fourier transform infrared(FTIR) spectra. The results of the Thermogravimetric analysis (TGA) exhibited that the higheraddition of 20% CMC into the pure PP slightly improved both the residue yields and thermalstability. The tensile strength of 20% CMC into pure PP was slightly increased and elongationreduced, compared with pure PP.

The graphene powder was used as a reinforcement in polyethylene terephthalate (PET) with various weight percentages 0.1, 0.5, 1 and 2 wt%. To prepare PET/graphene powder composites, melt-mixing process was followed. The crosslinking degree between PET and functionalized graphene increased, which was indicated by carbonyl indexes (Fourier transform infrared spectra) when interfaced with PET. The results of thermal properties showed that adding 2 wt% of graphene composites improved the thermal stability, transition glass temperature $$T_\mathrm{g}$$ , crystallinity temperature point and chemical properties of PET. The results of thermal gravimetric analysis showed that the highest addition of graphene (2 wt%) into the PET slightly improves both the residue yields and thermal stability. The tensile strength of PET was highly increased with the increased loading of graphene, and the elongation was reduced, compared with PET without filler. The results of X-ray diffraction curves showed that 2% incorporation of graphene into PET has good interfacial interaction and higher intensity. The scanning electron microscopy micrographs showed a high compatibility between the pure PET and graphene composite chains.

The durability of epoxy resins is an important factor in applications of composites to timber engineering. We carried out a comparative study of the effect of accelerated weathering on epoxy resins based on the glycidyl ether of bisphenol A (DGEBA) or hydrogenated diglycidyl ether of bisphenol A (HDGEBA) cured with 2,2,4-trimethylene-1,6-hexadiamine, using various characterization tools, including mechanical and thermal testing and SEM to evaluate the effect of exposure to UV light, moisture and elevated temperature cycles on the properties of the resins. Mechanical testing showed that after 6 months accelerated weathering reduced by 50% the tensile strength of DGEBA-TMDA while HDGEBA-TMDA epoxies lost slightly less strength over the same exposure period. Elongation at break increased after 6 months of accelerated weathering from 5.1 ± 0.1% to 7.5 ± 0.3% for DGEBA-TMDA epoxy specimens, and from 0.9 ± 0.3% to 2.0 ± 0.1% for HDGEBA-TMDA epoxy specimens. FTIR of the epoxies showed increases in the absorbance of hydroxyl and carbonyl groups for both epoxies on accelerated weathering, but the hydroxyl and carbonyl indexes reached values 90 and 40% higher respectively for DGEBA than HDGEBA-based epoxy resins. While susceptibility to accelerated weathering on the molecular scale was clearly greater for the DGEBA-based epoxy on the molecular scale, this did not translate into a significant deterioration in mechanical properties relative to HDGEBA over the time scale of the accelerated weathering experiments.

This study aims to investigate the effects of corn flour fillers on the mechanical and thermal properties and surface morphology of low-density polyethylene composites. Low-density polyethylene (LDPE) and low density polyethylene/corn flour (LDPE/CF) with different loadings of CF (5%‐20% w/w) were prepared in an internal mixer type Z-Blade mixer at 190°C and rotor speed of 50 rpm. Dynamic mechanical analysis (DMA), Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and tensile tests were analysed to investigate thermal and mechanical properties. Tensile tests displayed an increase in the tensile strength and modulus with the increase of CF loadings. The results of DMA tests showed significant improvements for the storage modulus and glass transition temperature, Tg. The results of TGA indicated that the addition of higher amounts of CF enhanced thermal stability.

This work aims to investigate the improvements of thermal and chemical properties of polyethylene terephthalate (PET) by using Multi-walled carbon nanotubes (MWCNTs). MWCNT were used as a reinforcement in polyethylene terephthalate with different weight percentages (0.1, 0.5, and 1) % respectively. The direct mixing process was used to prepare (polyethylene terephthalate / MWCNTs) composites. The ultrasonic mixing technique was applied to disperse the MWCNTs material into polyethylene terephthalate. The intensities of absorption of hydroxyl and carbonyl group decreased with increasing the addition of MWCNTs from (0.1-1%), comparing with pure PET. The results of TGA showed that the incorporation of MWCNTs into pure PET slightly improves the thermal stability because interfaces between multifuntionlized MWCNTs and pure PET causes of reducing brittle behavior and increased due to the high crosslinking of pure PET. The mechanical tests appeared significant improvements with increasing of MWCNTs concentrations. The SEM micrographs showed more voids between the pure PET chains before adding MWCNTs while MWCNTs-PET composites appeared more homogeneous, crosslink density and less voids between the chains.