Degradation of acrylonitrile-butadiene-styrene and polycarbonate by UV irradiation (original) (raw)
Related papers
RSC Advances, 2017
A new acrylic terpolymer, poly(methyl methacrylate-co-butyl acrylate-co-acrylic acid) [P(MMA-co-BA-co-AA)] of ultra-high molecular weight (UHMW) was synthesized via seeded emulsion polymerization. This polyacrylic showed good film properties; high transparency, water resistance and mechanical flexibility that may suitable for many environmental based applications such as coating, packaging, label sensors etc. In order to access the photo-stability of this material for environmental application, studies were conducted under UV illumination of a short-wavelength (l ¼ 254 nm) in air. The responses were collected at different irradiation times by using several characterization techniques: infrared/UV-visible spectroscopy (FTIR/UV-Vis), gel permeation chromatography (GPC), atomic force microscopy (AFM) and thermogravimetric analysis (TGA). Two distinguishable structures, cross-linked and fragmented chains, were formed under photo-irradiation at different times of exposure. The formation of cross-linked structures at short irradiation times (t < 60 min) increases the chain length as validated from the increase in average-molecular weight (M w), whilst at longer irradiation time the fragmentation causes a decrease in the chain length (decrease in M w). Only the chain scission at longer irradiation time (t > 60 min) causes the copolymer to degrade. The centre of reaction was identified at the pendent group and no effect of main chain destabilization was observed throughout the experimental condition. The occurrence of chain cleavage during photo-degradation causes chain-chain separation, as visually seen under the imaging technique and this coincides with the observed drop in thermal stability. Photo-oxidation was also proposed to occur simultaneously with photo-degradation as the irradiation was performed in air.
Polymer, 2002
Spatial effects in the degradation of poly(acrylonitrile±butadiene±styrene) (ABS) exposed to UVB radiation l 290±330 nm and oxygen in a weathering chamber at 318 K were studied by attenuated total re¯ectance Fourier transform infrared spectroscopy (ATR-FTIR). The polymer contained 2 wt% Tinuvin 770, a hindered amine stabilizer (HAS). ABS samples of thickness 4 mm were irradiated, microtomed, and sections of thickness 50 and 150 mm were studied as a function of treatment time. ATR-FTIR pro®ling indicated that the degradation was spatially heterogeneous: signi®cant amounts of photoproducts were detected only in the directly irradiated layer of depth < 50 mm. In this layer, major damage was re¯ected in the appearance of the hydroxyl (3600±3200 cm 21 ) and the carbonyl (1800± 1600 cm 21 ) peaks, and in the disappearance of the 967 cm 21 peak from 1,4 butadiene units (1,4 PB). The hydroxyl and carbonyl peaks were also detected in the second layer of thickness < 50 mm. Slight changes in the intensity of peaks in the above three spectral regions, compared to a nonirradiated reference sample, were also detected on the nonexposed sample side, and assigned to thermal degradation. For irradiation times up to < 2000 h, the spectra indicated damage of the butadiene structure, and no changes in the styrene±acrylonitrile (SAN) matrix. The present study con®rmed major conclusions deduced from 1D and 2D nondestructive electron spin resonance imaging (ESRI) experiments performed on the same samples in our laboratory, and provided additional information on the spatial distribution of stable degradation products. q
Profile of oxidation in irradiated polyethylene
1998
Following gamma irradiation in air which causes bond scission and yields large concentrations of peroxy radicals, maximum oxidation and an increase in crystallinity occurs on the surface of ultrahigh molecular weight polyethylene. Here, bimolecular reactions of peroxy radicals generate carbonyls, mostly ketones. On the polymer surface, peroxy radicals continue to react over time periods of years to generate carbonyls and chain scission. Peroxy radicals in the interior of the polymer abstract hydrogens and form hydroperoxides, inducing chain reactions and a slow but continue increase of ketone. Within the polymer sample, to a decreasing depth with increasing dose, a reduced concentration of oxygen is available to react with radiolytic radicals, so that more efficient crosslinking and a low level of hydroperoxide chain reaction occur. After long periods of time a surface maximum in carbonyl concentration is produced. Heating polyethylene in high pressures of oxygen accelerates the oxidative process.
Post-irradiation oxidation of different polyethylenes
Polymer Degradation and Stability, 2011
The radiation-induced oxidative degradation of polyethylenes (PEs) with different degrees of crystallinity was characterized after electron-beam irradiation and during storage at room temperature.
Positron annihilation studies of the effect of gamma irradiation dose in polymers
2003
Positron annihilation lifetime (PAL) technique has been applied to study the effect of gamma irradiation dose on the structure of low-density polyethylene and polystyrene. The positron annihilation lifetime measurements were performed with a conventional fast-fast coincidence system. Gamma irradiation was carried out at room temperature with a 60 Co gamma source up to a dose of 1000 kGy. The delayed lifetime spectra of irradiated and unirradiated samples were decomposed into three lifetime components. The lifetime parameters give indication of the free-volume size and concentration. It was found that the crosslinking efficiency in the polymer increases significantly with increasing irradiation dose. This appears as a decrease in the intensity of the long-lived positron lifetime components attributed to ortho-positronium formation.
Photodegradation kinetics of poly(para-substituted styrene) in solution
Polymer Degradation and Stability, 2008
The UV irradiation effects on stability of polystyrene, poly(4-methoxystyrene), poly(4-methylstyrene), poly(a-methylstyrene), poly(4-tert-butylstyrene), poly(4-chlorostyrene), and poly(4-bromostyrene) in dichloromethane, dichloromethane, tetrahydrofuran, and N,N-dimethylformamide solutions were studied in the presence of oxygen at different intervals of irradiation time. The photodegradation was studied at 293 K using fluorescence spectroscopy. Solutions of these polymers were accompanied by quenching of monomer and excimer emissions during the exposure of their solutions to UV light, and by a change in the structure of the fluorescence spectrum. Irradiation of poly(4-methylstyrene) and poly(amethylstyrene) at excitation wavelength of 265 nm showed an increase of fluorescence intensity of a broad band, at longer wavelength without clear maxima. This may indicate that photodestruction of these polymers by irradiation with light of frequency absorbed by the polymer, may start from a random chain scission, with the possibility of formation of polyene and carbonyl compounds.
Irradiation Effect on Photodegradation of Pure and Plasticized Poly (4-Methylstyrene) in Solid Films
Materials Sciences and Applications, 2014
The photodegradation of irradiated thin films of poly (para-methylstyrene) with 265 nm radiations in the presence of airand as a function of irradiation time has been studied using UV-VIS, fluorescence and FT-IR Spectroscopic techniques. The influence of phthalate and terephthalate plasticizers on stability of poly (para-methylstyrene) towards irradiations was also investigated. Blending with phthalate plasticizers was found to cause a higher efficiency of photodegradation than that obtained in doping with terephthalate plasticizers. The intensity of absorption was also found to increase with time of irradiation and in change in the shape of the spectra at longer wavelength, thus indicating a possibility of photodegradation of polymer chains. The analysis of the FT-IR spectra of the irradiated and non-irradiated samples, shows a predominant absorption associated with carbonyl compounds with 1740 cm −1. In addition, the observed increase in the intensities of the carbonyl and hydroxyl regions of the FT-IR spectra, have provided an evidence for the photodegradation as well as photo-oxidation of polymeric chains. The presence of the plasticizer in the polymer backbone was found to accelerate the photodegradation of polymeric chains.
Ultraviolet Irradiation Studies in a Polyester Using Positron Annihilation Spectroscopy
Positron Annihilation Lifetime Technique (PALT) and Doppler Broadening of Annihilation Radiation (DBAR) technique were utilized to study the effect of Ultraviolet (UV) radiation on a commercial polyester sample. The results for ortho-positronium (o-Ps) lifetime 3 and S-parameter indicate that at low and moderate doses the free-volume hole size and degree of crystallinity of the bulk is unaffected. At higher doses, the amorphous content decreases as shown by a decrease in S-parameter. This is due to a reordering of scission fragments. The variation of intensity of o-Ps component I 3 with UV irradiation time, at low and moderate doses, indicates that the number density of freevolume holes has slightly increased as a consequence of the effect of chain scission on polymer microstructure. This is however followed by a drop in its value, and then, saturation. These aspects are explained in this paper.
The results of Positron Annihilation Lifetime Technique (PALT) and Doppler Broadening Spectroscopy (DBS) studies on polyvinylalcoholpolyvinylpyrrolidone (PVA-PVP) blend are discussed in this paper. The Sparameter of DBS technique, which is a measure of positrons annihilating in the amorphous regions, on interaction with low momentum electrons, is found to increase when comparing the results for un-irradiated sample and samples irradiated to low doses of Ultraviolet (UV) irradiation. On receiving high dosage of UV irradiation, there is a drastic drop in S-parameter, even below the value for un-irradiated sample, followed by saturation, on further irradiation. The longest lifetime component т 3 , which is a measure of o-Ps annihilation from free-volume sites shows an initial rise, followed soon (with increasing UV exposure time) by a decrease even below the value for unirradiated sample, and subsequent saturation in value, even for very small dose of UV irradiation. UV irradiation is known to induce micro-structural changes in the polymeric samples and the effectdegradation or cross-linkingdepends on the nature of the sample as well as irradiation conditions. An increase in S-parameter indicates an increased amorphous nature of the sample, probably caused by photo-scission of polymer chains. The drop in Sparameter beyond a moderate dose indicates a dynamic process involving scission followed by re-ordering of crystallites.