Effect of gamma-ray irradiation on the mechanical strength of polystyrene-ferrocene composite (original) (raw)
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Effects of radiation on the mechanical properties of structural materials
Journal of Nuclear Materials, 1994
Blends containing 3 wt % low molecular weight polybutadiene ( P B ) in a polystyrene (PS) matrix were prepared via a precipitation technique that yielded spherical, submicron pools of PB. Tensile specimens made from these blends were then irradiated with high energy electrons in air a t dose levels from 0 to 70 Mrads. The blends, which previously showed high levels of toughness approaching that of high impact PS, lost all enhanced toughness when irradiated above 10 Mrads. Analysis of pure PS specimens irradiated over the dose range from 0 to 45 Mrads showed no appreciable dependence of mechanical behavior on dose level. Molecular weight studies of the polybutadiene demonstrated only a very modest increase in molecular weight in the dose range studied here; therefore, reduced mobility of the P B in the blends was not the reason for the dramatic drop in toughness with radiation dose. It was concluded that radiation-induced scission of the PS near the surface of the blends resulted in a significant local reduction in molecular weight. This degraded layer led to premature craze failure and hence a low level of toughness. It was demonstrated that the absence of oxygen during the irradiation process or the removal of the scissioned surface layer via mechanical abrasion resulted in a recovery of toughness. 0
Journal of Nuclear Materials, 2019
Inorganic Polymers (IPs) are interesting alternative binder materials to Ordinary Portland Cement (OPC). They could be potentially used in applications such as nuclear safety structures and radioactive waste management since they are highly chemically and thermally resistant. However, their chemical and mechanical stability still has to be proven when irradiated at the very early age. This study investigated the effect of gamma irradiation on the mechanical and microstructural properties of IPs cured for 1 hour, 24 hours or 28 days. For that purpose, IPs were irradiated using different dose rates (1.6 Gy/h, 7.1 Gy/h, 152 Gy/h and 2 kGy/h) until different absorbed doses with a maximum of 624 kGy. The effects were evaluated by means of compressive strength tests, microstructural analysis by image analysis, porosity analysis (water absorption and MIP), thermogravimetric analysis (TGA) and infrared spectrometry. For each irradiation test, non-irradiated samples were kept as a reference at the same environmental conditions as the irradiated samples. The results were compared with similar studies on OPC-based samples. At low doses (< 5 kGy) no statistically significant change has been found. Above 5 kGy however, a significant increase in compressive strength was found for all the samples tested. An increase up to 22 % in compressive strength was observed for the samples irradiated at 2 kGy/h. Gamma radiation induced carbonation, Fe 3+ reduction and polymerization could explain the strength increase but need further investigation.
Toughness behavior of gamma-irradiated polycarbonate
Polymer Testing, 2007
The aim of the present work was to establish the relationship between dynamic behavior of Bisphenol A polycarbonate (BAPC) and degradation by gamma irradiation. The BAPC was exposed to 340 kGy dose and the molecular weight was evaluated by Size Exclusion Chromatography (SEC). A modified split Hopkinson pressure bar was used to measure stress-strain dynamic relations. The results showed little change in the dynamic behavior of irradiated BAPC in the highest strain rate used in this work, in spite of the high decrease in the molecular weight of irradiated BAPC. The lowest strain rate used in this work produced the highest change in the dynamic behavior of irradiated BAPC.
Gamma irradiation effects on impact strength and thermal properties of SBR-toughened polystyrene
2004
WlToLD BRolToW|2'' VIcToR M. cASTAŃol'2'';alv t Honte]', GoNZALo MARTINEZ-BłRRERł1 a)') and thermal properties of SBR-toughened polystyrene summaIy' Effects of chemical structurą composition, thelma] stability and mo1eĆular wei8hts of ihe rubber Phase in amorphous Polystyrene + siy_ rene/butadiene rubber (SBR) blends on impact behavior were investigated. Blends v/ith 5, 10 and 13 \r'r't' % of sBR embedded into a ńsid polysi}Tene matrix were prepared as well as the samples without SBR. For all blends the Izod impact tests were pe omed and those with ihe besi impact strength values were submiited to gamma inadiatior The lzod impact tesis of the inadiated sańPles \Ą'ele ihen Perfolmed' Themo8ravimetfic analysis (TGA) and differential scanning calorimeEy @SC) runs were made for both irra diated and noi inadiated blends. Blends compositions with the highest impaci energies have been defined. Gamma irradiation initially enhances the impdci ellerSies but rhen rea,hes a mr\imum around 150 kcy above Bhi.h the impact shength eventually becomes lower than in the samples noi subje.led Lo rrradi",ron.
The Effect of Irradiation on Mechanical and Thermal Properties of Selected Types of Polymers
Polymers, 2018
This article deals with the influence of electron-beam radiation on the micro-mechanical, thermo-mechanical, and structural properties of selected polymers. In the search for the desired improvement of polymers, it is possible to use, inter alia, one particular possible modification-Namely, crosslinking-Which is a process during which macromolecular chains start to connect to each other and, thus, create the spatial network in the structure. In the course of the treatment of the ionizing radiation, two actions can occur: crosslinking and scission of macromolecules, or degradation. Both these processes run in parallel. Using the crosslinking technology, standard and technical polymers can acquire the more "expensive" high-tech polymeric material properties and, thus, replace these materials in many applications. The polymers that were tested were selected from across the whole spectra of thermoplastics, ranging from commodity polymers, technical polymers, as well as high-performance polymers. These polymers were irradiated by different doses of beta radiation (33, 66, 99, 132, 165, and 198 kGy). The micro-mechanical and thermo-mechanical properties of these polymers were measured. When considering the results, it is obvious that irradiation acts on each polymer differently but, always when the optimal dose was found, the mechanical properties increased by up to 36%. The changes of micro-mechanical and thermo-mechanical properties were confirmed by structural measurement when the change of the micro-hardness and modulus corresponded to the crystalline phase change as determined by X-ray and gel content.
Effect of ionizing radiation on mechanical properties of glass-fiber-filled polyethylene
Soviet Materials Science, 1978
This study aimed to evaluate the effect of radiation therapy (RT) on mechanical properties and translucency of monolithic zirconia. Yttria-stabilized zirconia (Y-PSZ) materials (14 × 4.0 × 1.5 mm) were divided in four experimental groups (n = 30): High-translucency/control (HT/C), high-translucency/irradiated (HT/I), low-translucency/ control (LT/C), low-translucency/irradiated (LT/I). Irradiated specimens were submitted to a single dose irradiation of 70 Gray. Flexural strength (n = 10) (FS-3-point bending test), fatigue limits (n = 15) at 100,000 cycles (FLs-staircase approach), and translucency (n = 5) (TP-dental spectrometer) were analyzed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the materials. FS and TP data were analyzed by one-way Analysis of Variance (ANOVA) and Tukey HSD. FLs were analyzed using Dixon and Mood method, and Kaplan-Meier survival analysis. RT affected FS of LT zirconia (p = .032) but not of HT zirconia (p = .86). FLs and TP of both materials were not affected by RT (p > .05). Higher cubic content after RT was observed. In conclusion, RT may affect flexural strength and crystalline content of zirconia-based materials, but this effect was not observed under fatigue. Translucency of Y-PSZ restorations is also not affected by RT.
Mechanical response of high density polyethylene to gamma radiation from a Cobalt-60 irradiator
Polymer Testing, 2016
The response of High Density Polyethylene (HDPE) to gamma irradiation is important for a variety of applications, from the durability of hip replacements after gamma sterilization to the degradation of power cable insulation that guides the licensing and regulation of nuclear power plants. HDPE samples are irradiated with up to 58.8 kiloGray from a Cobalt-60 gamma irradiator, and mechanical properties are examined using models assuming exponential behavior. Increasing the radiation dose led to increases to the ultimate strength and the Rockwell hardness with a corresponding reduction in the maximum elongation at ultimate strength, supporting the hypothesis that the samples increased their strength and brittleness.
Polymer Bulletin, 2015
Crosslinking of polyamide 6 (PA) and filled one with glass fibres (PA/ GF) was initiated via macroradical formation by gamma irradiation either in air or in inert argon atmosphere. The crosslinked portion was found to start at absorbed dose around 300 kGy and achieved about 60 and 40 wt% for PA and PA/GF, respectively, if irradiation proceeded in inert, while in air molecular weight increase was only observed without crosslinked gel formation. DSC indicated that irradiation leads to a decrease in crystallinity as well as lamellae thickness. Besides crosslinking, scission of polymer chains also occurs. Modest increase of impact strength was found for PA while small decrease for PA/GF was observed. The dependence of Young's modulus values on the irradiation dose indicates a minimum around gel point being more pronounced for PA compared to the composite. Irradiation resulted in minor changes in tensile strength and elongation at break while a substantial increase in the elongation at yield was found for PA if irradiated in inert atmosphere. Generally, the application of an optimal dose of gamma irradiation in air results in an increase of toughness of PA without changing other mechanical properties.
Polymer Engineering & Science, 2012
In the present article, the effect of c-ray irradiation of doses 14.85, 30, and 45 kGy on the thermomechanical and tensile properties of blends of cis-polyisoprene and trans-polyisoprene have been investigated. The results on thermomechanical properties show that glass transition temperature increases and height of tan d of material decreases with increasing radiation dose. Tensile measurements reveal that all the tensile properties like tensile strength, Young's modulus, and toughness also show an increasing trend with increasing dose of radiation. This increasing behavior of both thermomechanical and tensile properties has been explained through crystallinity and crosslink density induced by radiation.
Radiation Degradation of Polytetrafluoroethylene-Lead Composites
Journal of Materials Engineering and Performance, 2015
Composites of polytetrafluoroethylene (PTFE) with Pb (0-15 wt.%) were fabricated and irradiated up to 50 kGy in a 60 Co-gamma chamber to evaluate the effect of Pb in improving the radiation tolerance of PTFE. Thermal and mechanical properties were measured for the irradiated and un-irradiated PTFE samples and its composites. The number average molecular weight of PTFE was estimated at different doses from the enthalpy of crystallization values obtained by Differential Scanning Calorimetry. Reduction in the percentage increase in the enthalpy of crystallization and melting of PTFE-15% Pb composite, during irradiation indicated the stabilizing effect of lead on PTFE. Surface morphology of PTFE and its composites revealed that the formation of micro-cracks and blisters in PTFE, owing to radiation damage was controlled by lead. Elongation at break values and SEM images of the irradiated composites indicated that 15% Pb offered better stability to PTFE than 10% Pb.