Electron beam irradiation of epoxidized natural rubber (original) (raw)
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Electron beam irradiation of epoxidized natural rubber: FTIR studies
Polymer International, 2000
The eect of irradiation on ENR50 was studied with particular attention to irradiation-induced crosslinking. ENR50 was irradiated by using a 3.0 MeV electron beam machine with doses ranging from 20 to 200 kGy. The in¯uence of several additives such as TMPTA, Irganox1010 and tribasic lead sulfate on irrradiation-induced crosslinking of ENR50 was investigated. The gel fraction, Ts, M100, Eb, hardness and Tg were used to follow the irradiation-induced crosslinking of the rubber. Results revealed that the increase in gel fraction upon irradiation of pure ENR50 could be associated with both irradiation-induced crosslinking as well as ring opening side chain reaction of oxirane group. The observation on the trend shown in the properties studied con®rmed that TMPTA is ecient in enhancing the irradiation-induced crosslinking of ENR50. The addition of Irganox1010 and tribasic lead sulfate found to inhibit irradiation-induced crosslinking of ENR50 to considerable extent. This in¯uence of stabilizing additives in particular, antioxidant, was observed to be more prominent at lower doses. The importance of TMPTA in preventing ring opening side chain reactions as well as the role of the stabilizing additives in introducing free chain ends are also discussed. However studies did not reveal the exact nature of irradiation-induced reactions involved in ENR. Ó
European Polymer Journal, 2001
The eect of irradiation on the tensile and dynamic mechanical properties of ENR50 (ENR: epoxidized natural rubber) was investigated. ENR50 was irradiated using a 3.0 MeV electron beam machine with doses ranging from 20 to 200 kGy. The in¯uence of several additives such as trimethylolpropane triacrylate (TMPTA), Irganox1010 and tribasic lead sulfate (TBLS) on the irradiation-induced changes of ENR50 was investigated. The general improvement on the tensile, as well as dynamic mechanical properties with irradiation indicates the formation of irradiation-induced crosslinks. An appreciable increase in T g is observed with irradiation while the enhancement in stress at break is found to be marginal. This observation agrees well with the relatively small increase in storage modulus occurred beyond the T g of the irradiated ENR. This in return reveals that only a small degree of crosslinking is achieved through irradiation. Based on these factors it can be inferred that the gradual increase in T g upon irradiation of ENR50 could be associated with the occurrence of irradiation-induced ring opening side chain reaction of the oxirane group and irradiationinduced oxidation at the cis double bond along with the irradiation-induced crosslinking. From the observation in the properties studied it con®rms that TMPTA is ecient in enhancing the irradiation-induced crosslinking of ENR50. The addition of Irganox1010 and TBLS are found to impart considerable stability to ENR50, although the antioxidant did cause some inhibition of crosslinking. The acceleration of crosslinking by the TMPTA as well as the inhibition of crosslinking the added stabilizing additives were further con®rmed by using gel fraction data. However, the studies did not reveal the exact nature of irradiation-induced reactions involved in ENR. Ó
Polymer Degradation and Stability, 2006
The effect of irradiation on tensile, dynamic mechanical properties, thermal properties and morphology of ENR-50, EVA and ENR-50/EVA blend was investigated. All the samples were irradiated using a 3.0 MeV electron beam (EB) machine with doses ranging from 20 to 100 kGy. Results indicate that the gel fraction of ENR-50, EVA and ENR-50/EVA blend increases with irradiation dose. Concerning tensile properties, it can be seen that EB radiation increases the tensile strength of all the samples, increases the elongation at break of ENR-50 and ENR-50/EVA blend, reduces the elongation at break of EVA, increases M200 (modulus at 200% strain) of ENR-50 and EVA, while decreases M200 of the ENR-50/EVA blend. For dynamic mechanical studies, it was found that EB radiation increases the T g of all the samples due to the effect of irradiation-induced crosslinking. The compatibility of ENR-50/EVA blend also found to be improving upon irradiation. In the case of thermal properties, it was detected that T m , T c and the degree of crystallinity of ENR-50/EVA blend increase with an increase in irradiation dose. This was due to the perfection in the crystal growth occurring upon radiation. Morphology changes play a major role in the changes of the properties of ENR-50/EVA blend. Finally, it can be concluded that ENR-50/EVA blend can be vulcanized by EB radiation.
Polymer Degradation and Stability, 1999
The eects of 3 dierent types of antioxidants; a hindered phenol, a phosphite and a hindered amine light stabilizer (HALS) on the radiation-induced crosslinking and oxidative degradation of 70a30 polyvinyl chloride (PVC)/epoxidised natural rubber (ENR) blend with a crosslinking agent were studied. The gel fraction, tensile strength, elongation at break, modulus and hardness were used to follow the irradiation-induced crosslinking and oxidative degradation of the blend. Results on mechanical properties implied that the hindered phenol is an eective antioxidant for the investigated PVC/ENR blend system. The modulus and hardness results revealed that addition of antioxidant to the blend favours the formation of free ends in the crosslinked network upon irradiation. The Fourier transform infrared spectroscopy analysis indicated that the radiolysis products of hindered phenol at 60 kGy induce post irradiation reaction in PVC/ENR blends. However, studies did not reveal the exact nature of the radiolysis product responsible. # 1999 Elsevier Science Ltd. All rights reserved. 0141-3910/99/$ -see front matter # 1999 Elsevier Science Ltd. All rights reserved. P I I : S 0 1 4 1 -3 9 1 0 ( 9 9 ) 0 0 0 3 9 -7 Polymer Degradation and Stability 65 (1999) 481±490
Modification of PVC/ENR blend by electron beam irradiation: effect of crosslinking agents
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1999
The eect of irradiation on ENR50 was studied with particular attention to irradiation-induced crosslinking. ENR50 was irradiated by using a 3.0 MeV electron beam machine with doses ranging from 20 to 200 kGy. The in¯uence of several additives such as TMPTA, Irganox1010 and tribasic lead sulfate on irrradiation-induced crosslinking of ENR50 was investigated. The gel fraction, Ts, M100, Eb, hardness and Tg were used to follow the irradiation-induced crosslinking of the rubber. Results revealed that the increase in gel fraction upon irradiation of pure ENR50 could be associated with both irradiation-induced crosslinking as well as ring opening side chain reaction of oxirane group. The observation on the trend shown in the properties studied con®rmed that TMPTA is ecient in enhancing the irradiation-induced crosslinking of ENR50. The addition of Irganox1010 and tribasic lead sulfate found to inhibit irradiation-induced crosslinking of ENR50 to considerable extent. This in¯uence of stabilizing additives in particular, antioxidant, was observed to be more prominent at lower doses. The importance of TMPTA in preventing ring opening side chain reactions as well as the role of the stabilizing additives in introducing free chain ends are also discussed. However studies did not reveal the exact nature of irradiation-induced reactions involved in ENR. Ó
Journal of Applied Polymer Science, 2001
Electron-beam initiated crosslinking of poly(vinyl chloride)/epoxidized natural rubber blends, which contained trimethylolpropane triacrylate (TMPTA), was carried out over a range of irradiation doses (20 -200 kGy) and concentrations of TMPTA (1-5 phr). The gel content increased with the irradiation dose and the TMPTA level, although the increase was marginal at higher doses and higher TMPTA levels. Blends containing 3-4 phr TMPTA achieved optimum crosslinking, which in effect caused the maximum tensile strength (TS) at a dose of 70 kGy. A further addition of TMPTA caused a decline in the TS above 40 kGy that was due to embrittlement, which is a consequence of excessive crosslinking and the breakdown of the network structure. The possible formation of a more open network as a result of the breakdown of the network structure was further confirmed by the modulus results. Dynamic mechanical analysis (tan ␦ curve) and scanning electron microscopy studies on samples irradiated at 0 and 200 kGy were undertaken in order to gain further evidence on the irradiationinduced crosslinking. The plasticizing effect of TMPTA prior to irradiation and the formation of microgels upon irradiation were also discussed.
Journal of Applied Polymer Science, 2001
Electron-beam initiated crosslinking of a poly(vinyl chloride)/epoxidized natural rubber blend (PVC/ENR), which contained trimethylolpropane triacrylate (TMPTA), was carried out over a range of irradiation doses (20 -200 kGy) and concentrations of TMPTA (1-5 phr). The gelation dose was determined by a method proposed by Charlesby. It was evident from the gelation dose, resilience, hysteresis, glasstransition temperature (T g ), IR spectroscopy, and scanning electron microscopy studies that the miscible PVC/ENR blend underwent crosslinking by electron-beam irradiation. The acceleration of crosslinking by the TMPTA was further confirmed in this study. Agreement of the results with a theory relating the T g with the distance between crosslinks provided further evidence of irradiation-induced crosslinking. The possible mechanism of crosslinking induced by the irradiation between PVC and ENR is also proposed.
Evaluation of Electron Induced Crosslinking of Masticated Natural Rubber at Different Temperatures
Polymers, 2019
In this work, natural rubber (NR) was masticated using an internal mixer to fit the requirements of reactive blending with polylactide and characterized by size exclusion chromatography (SEC), Fourier-transform infrared (FT-IR) spectroscopy and dynamic rheology measurements. Subsequently, the effect of elevated temperatures (25 • C, 80 • C, and 170 • C) on the electron beam (EB) induced crosslinking and degradation of masticated natural rubber (mNR) in a nitrogen atmosphere without adding crosslinking agents has been investigated. The sol gel investigation showed that the gel dose of mNR slightly increased with increasing irradiation temperature, which is also confirmed by the swelling test. The chain scission to crosslinking ratio (G s /G x) was found to be less than 1 for irradiated mNR at 25 • C and 80 • C, suggesting a dominating crosslinking behavior of mNR. However, a significant increase of G s /G x ratio (~1.12) was observed for mNR irradiated at 170 • C due to the enhanced thermal degradation behavior at high temperature. A remarkably improved elasticity (higher complex viscosity, higher storage modulus, and longer relaxation time) for EB modified mNR was demonstrated by dynamic rheological analysis. Particularly, the samples modified at higher temperatures represented more pronounced elasticity behavior which resulted from the higher number of branches and/or the longer branched chains.
Journal of Applied Polymer Science, 2011
Linear low-density polyethylene/soya powder blends were prepared by using an internal mixer at 150 C. The soya powder content ranged from 5 to 40 wt %. Epoxidized natural rubber with 50 mol % epoxidation (ENR 50) was added as a compatibilizer. The blends were irradiated by electron beam (EB) at a constant dose of 30 kGy. The changes in gel fraction, tensile properties, morphological and thermal properties of the samples were investigated. The gel content increased after EB irradiation. However, the increment of gel content was hindered by increasing soya powder content. The tensile strength and Young's modulus of the blends were increased by EB whereas the elongation at break decreased. The tensile frac-ture surface also support the reduction of elongation at break by EB irradiation. Further analysis on the irradiated blends using Fourier transform infrared spectra indicated an increase of oxygenated product after undergoing EB irradiation. The differential scanning calorimetry result indicated that the melting temperature of the blends decreased after EB irradiation whereas the crystallinity increased. EB irradiation also enhanced the thermal stability of the blends as indicated by thermogravimetric analysis. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: 5220-5228, 2012
International Journal of Molecular Sciences
Composites based on natural rubber reinforced with mineral (precipitated silica and chalk) and organic (sawdust and hemp) fillers in amount of 50 phr were obtained by peroxide cross-linking in the presence of trimethylolpropane trimethacrylate and irradiated by electron beam in the dose range of 150 and 450 kGy with the purpose of degradation. The composites mechanical characteristics, gel fraction, cross-linking degree, water uptake and weight loss in water and toluene were evaluated by specific analysis. The changes in structure and morphology were also studied by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy. Based on the results obtained in the structural analysis, possible mechanisms specific to degradation are proposed. The increasing of irradiation dose to 450 kGy produced larger agglomerated structures, cracks and micro voids on the surface, as a result of the degradation process. This is consistent with that the increasing of irradiation dose to 4...