Effect of electron beam radiation on the mechanical and thermal properties of poly(4-methylpentene-1) (original) (raw)
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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.
Electron beam irradiation effects on poly(ethylene terephthalate)
Radiation Physics and Chemistry, 2007
Changes in poly(ethylene terephthalate) subjected to electron beam irradiation at doses up to 15 MGy and dose rate of 1.65 MGy/h, were investigated by differential scanning calorimetry, molecular weight measurement, X-ray photoelectron spectroscopy, and scanning electron microscopy. Irradiated samples showed a decrease of molecular weight with a minimum at 5 MGy, which is attributed to chain scission of the macromolecules and then an increase at further doses due to branching and some degradation effect. Irradiation in air is not an important factor because the high dose rate of irradiation inhibits oxygen diffusion in the samples. r
Physical and thermal properties of 8MeV electron beam irradiated HPMC polymer films
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2008
Microstructural modification in hydroxypropyl methylcellulose (HPMC) polymer films induced by electron irradiation is studied. Irradiation was performed in air at room temperature using a 8 MeV electron accelerator at doses of 25, 50, 75 and 100 kGy. Irradiation can be used to crosslink or degrade the desired component or to fix the polymer morphology. Changes in microstructural parameters, crystallinity and thermal properties in virgin and irradiated HPMC films have been studied using wide angle X-ray scattering data and differential scanning calorimetry. The heat of fusion and the degree of crystallinity are found to be highest for unirradiated HPMC and the crystallite size is larger in virgin HPMC films.
Effect of electron beam irradiation on thermal and mechanical properties of epoxy polymer
2017
This study investigates the thermal and mechanical properties of epoxy polymer after exposure to different doses of electron beam irradiation. The epoxy polymer was prepared using epoxy-diane resin ED-20 cured by polyethylenepolyamine. The irradiation of the samples was carried out with doses of 30, 100 and 300 kGy. The effects of doses on thermal and mechanical properties of the epoxy polymer were investigated by the methods of thermal gravimetric analysis, tensile test, and dynamic mechanical analysis. The thermal properties of the epoxy polymer slightly increased after irradiation at the heating in air. The tensile strength and Young's modulus of the epoxy polymer increased by the action of electron beam up to dose of 100 kGy and then decreased. The elongation at break decreased with increasing the irradiation dose.
Royal Society Open Science
The influence of electron-beam irradiation on polypropylene (PP) and high-density polyethylene (HDPE) was investigated with a focus on crystallization. A high-temperature (200°C) creep test revealed that the HDPE gradually increased cross-linking density in the range 30–120 kGy, while the PP underwent a chain scission which was quantitatively evaluated by gel permeation chromatography. The mechanical properties were measured in the range -150 to 200°C by a dynamic mechanical analysis. A small presence of C=C and C=O bonds was found in the irradiated PP by a Fourier transform infrared spectroscopy. Crystallization kinetics measured by differential scanning calorimetry and hot-stage optical microscopy results were influenced tremendously by irradiation for HDPE and to a lesser extent for PP. Irradiation caused a decrease in both the number of nucleation centres and the growth rate of individual spherulites. Crystallization was analysed in detail with the help of Hoffman–Lauritzen, Avr...
Radiation Physics and Chemistry, 2014
Electron beam irradiation in polyamide-6 produced higher crosslinking than in polyamide-6,6. Crosslinking took place mainly in the amorphous phase of the polymer. Polyamide-6 melting point slightly decreased with the increase in irradiation dose and crystallinity remained practically unchanged. Mechanical properties were strongly affected by irradiation dose. Irradiation above Tg significantly increased the changes in thermal and mechanical properties respect to irradiation at ambient temperature.
Dose and Dose-rate Dependence of Polyethylene Irradiation with Electron Beams “in Air”
Journal of Materials Engineering and Performance, 2007
The chemical and physical properties of ultra-high-molecular-weight-polyethylene (UHMWPE) can be modified by high absorption dose of ionizing radiations. Energetic electron beams, 5 MeV in energy, with a penetration depth higher than 1 cm, can be used to deposit electron energy in thick UHMWPE. Different doses and different dose-rates have been employed at room temperature to irradiate the polyethylene samples in air. Mechanical measurements of tensile strength, wear resistance and hardness were performed on the pristine and electron-irradiated polymers. Results suggested the better irradiation conditions in order to optimize the mechanical properties of the polymer. Special medical applications of the electronirradiated UHMWPE are presented and discussed.
Influence of electron beam irradiation on physicochemical properties of poly(trimethylene carbonate)
Polymer Degradation and Stability, 2011
Electron beam (EB) irradiation of poly(trimethylene carbonate) (PTMC), an amorphous, biodegradable polymer used in the field of biomaterials, results in predominant cross-linking and finally in the formation of gel fraction, thus enabling modification of physicochemical properties of this material without significant changes in its chemical structure. PTMC films (M w : 167e553 kg mol À1 ) were irradiated with different doses using an electron accelerator. Irradiation with a standard sterilization dose of 25 kGy caused neither significant changes in the chemical composition of the polymer nor significant deterioration of its mechanical properties. Changes in viscosity-, number-, weight-, and z-average molecular weights of PTMC for doses lower than the gelation dose (D g ) as well as gelesol analysis and swelling tests for doses above D g indicate domination of cross-linking over degradation. EB irradiation can be considered as an effective tool for increasing the average molecular weight of PTMC and sterilization of PTMC-based biomaterials.
WAXD and FTIR studies of electron beam irradiated biodegradable polymers
Poly(L-lactic acid) (PLLA) and poly(ε-caprolactone) (PCL) have been receiving much attention lately due to their biodegradability in human body as well as in the soil, biocompatibility, environmentally friendly characteristics and non-toxicity. Morphology of biodegradable polymers affects the rate of their biodegradation. A polymer that has high degree of crystallinity will degrade at a slower rate due to the inherent increased stability. PCL homopolymer cross-linking degree increases with increasing doses of high energy radiation. On the other hand, the irradiation of PLLA homopolymer promotes mainly chain-scissions at doses below 250 kGy. In the present work, twin screw extruded films of PLLA and PCL biodegradable homopolymers and 50:50 (w:w) blend were electron beam irradiated using electron beam accelerator Dynamitron (E = 1.5 MeV) from Radiation Dynamics, Inc. at doses in the range of 50 to 1000 kGy in order to evaluate the effect of electron beam radiation on the homopolymers and blend. Wide-angle X-ray diffraction (WAXD) patterns of non irradiated and irradiated samples were obtained using a diffractometer Rigaku Denki Co. Ltd., Multiflex model; and FTIR spectra was obtained using a NICOLET 4700, ATR technique, ZnSe crystal at 45°. By WAXD patterns of as extruded non irradiated and irradiated PLLA it was observed broad diffusion peaks corresponding to amorphous polymer. There was a slight increase of the mean crystallite size of PCL homopolymer with increasing radiation dose. PCL crystalline index (CI) was 68% and decreased with radiation dose above 500 kGy. On the other hand. PLLA CI was 10% and increased with radiation dose above 750 kGy. On the other hand, PLLA presence on the 50:50 blend did not interfere on the observed mean crystallite size increase up to 250 kGy. From 500 kGy to 1 MGy the crystallite size of PCL was a little bigger in the blend than the homopolymer. Also it could be observed that the PLLA peak increase at 14.2° was affected by PCL presence on the blend above 750 kGy. In contrast, FTIR results have shown that this technique was not sensitive enough to observe the degradation promoted by ionizing radiation of the studied homopolymers and blends, and neither on the miscibility of the blends.
Properties of Selected Polymers after Radiation Cross-linking
2012
Radiation processing involves the use of natural or manmade sources of high energy radiation on an industrial scale. The principle of radiation processing is the ability of high energy radiation to produce reactive cations, anions and free radicals in materials. The industrial applications of the radiation processing of plastics and composites include polymerization, cross-linking, degradation and grafting. Radiation processing mainly involves the use of either electron beams from electron accelerators or gamma radiation from Cobalt-60 sources. The TPE-E thermoplastic elastomer, LDPE low density polyethylene and PA6 polyamide 6 tested showed significant changes of temperature stability and mechanical properties after irradiation. From this point-of-view, new applications could also be seen in areas with service temperatures higher than their former melting point. The comparison of the temperature stability and mechanical properties of irradiated and nonirradiated TPE-E, LDPE and PA6...