International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry最新文献

{"title":"Effect of substituted methyl group on the main-chain scission of alkyl radical in solid","authors":"Tsuneki Ichikawa","doi":"10.1016/1359-0197(92)90071-M","DOIUrl":"10.1016/1359-0197(92)90071-M","url":null,"abstract":"<div><p>ESR measurement of alkyl radicals generated by γ-irradiation of solid polymethylpentanes and polymethylhexanes at 77 K has been carried out to elucidate the effect of substituted methyl group on the scission of alkane main chains. Alkyl radicals initially generated by the scission of the C-H bond are primary radicals, penultimate secondary radicals, or penultimate tertiary radicals if all the penultimate carbon atoms of alkane molecules are tertiary ones. The primary radicals are β-scissile if the β- and γ-carbon are both tertiary. The secondary radicals are stable and not β-scissile. The tertiary radicals are β-scissile if the γ-carbon is tertiary. β-scission does not take place if the γ-carbon is the secondary, since the β-scission induces the conversion of the precursor radicals to unstable primary radicals. A strain introduced into a scissile C-C bond by methyl substitution promoted the β-scission.</p></div>","PeriodicalId":14262,"journal":{"name":"International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry","volume":"40 2","pages":"Pages 139-143"},"PeriodicalIF":0.0,"publicationDate":"1992-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/1359-0197(92)90071-M","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88892115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Broad line NMR studies on radiation effects on polymers","authors":"J. Sohma","doi":"10.1016/1359-0197(92)90069-R","DOIUrl":"10.1016/1359-0197(92)90069-R","url":null,"abstract":"<div><p>Our previous studies on the radiation effect on polymers made by using the broad line (BL) NMR technique are autoreviewed with emphasis on the usefulness of this technique. The BL NMR was widely applied, before the prevalence of the modern pulse NMR technique, to study the change of molecular motion caused by either the crosslink or the main-chain scission in solid polymers, since both line-shape and line-width of the BL NMR are sensitive to the molecular motion. Low- and high-density polyethylenes grafted with butadiene by γ-rays were examined before and after the crosslinking induced by heat-treatment with dicumyl peroxide. The crosslinking was found to occur between grafted polybutadiene branches. Polytetrafluoroethylene irradiated with neutron-beam was examined before and after heat-treatment. The results show that heat-treatment causes the formation of paracrystals of radiation-scissored polymer chains and hinders the molecular motion. Response of fluorinated ethylenepropylene copolymer to the neutron-irradiation was quite different: a small fluoropropylene fraction inhibited the paracrystal formation.</p></div>","PeriodicalId":14262,"journal":{"name":"International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry","volume":"40 2","pages":"Pages 121-126"},"PeriodicalIF":0.0,"publicationDate":"1992-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/1359-0197(92)90069-R","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82908911","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis of electro-responsive hydrogels by radiation polymerization of sodium acrylate","authors":"Isao Kaetsu ,&nbsp;Kumao Uchida ,&nbsp;Yasuji Morita ,&nbsp;Masayoshi Okubo","doi":"10.1016/1359-0197(92)90074-P","DOIUrl":"10.1016/1359-0197(92)90074-P","url":null,"abstract":"<div><p>Sodium acrylate-crosslinker (polyethyleneglycol dimethacrylate or diethyleneglycol dimethacrylate) copolymers were synthesized by photopolymerization and γ-ray-induced polymerization. The copolymer gels had large hydrophilicity. The electrically-responsive changes in weight were studied by sandwiching them between the two electrodes and applying repeatedly the electric field. Both the copolymer gels showed the reversible weight change in response to the on-off switching of the electric field. The response of the copolymer gel with polyethyleneglycol dimethacrylate is sharper than that of the copolymer with diethyleneglycol dimethacrylate. Release of methylene blue a model drug from the copolymer gels was found to occur intermittently in response to the on-off switching. The intermittent release was attributed to the squeezing effect due to the shrinkage of polyelectrolyte gels caused by electrophoretic movement of polymeric anions.</p></div>","PeriodicalId":14262,"journal":{"name":"International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry","volume":"40 2","pages":"Pages 157-160"},"PeriodicalIF":0.0,"publicationDate":"1992-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/1359-0197(92)90074-P","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76208169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation and reactivity of dimer radical cations of 4-methoxystyrene","authors":"Sachiko Tojo,&nbsp;Susumu Toki,&nbsp;Setsuo Takamuku","doi":"10.1016/1359-0197(92)90064-M","DOIUrl":"10.1016/1359-0197(92)90064-M","url":null,"abstract":"<div><p>One-electron oxidation of 4-methoxystyrene (<strong>1</strong>) and the following reactions of the radical cations, <strong>1</strong>⁺· have been investigated by pulse radiolysis of <strong>1</strong> in 1,2-dichloroethane at room temperature and 77 K matrix γ-irradiation in butyl chloride. Monomer radical cations, <strong>1</strong>⁺· with λ_max at 600 nm generated immediately after an 8-ns pulse irradiation react with <strong>1</strong> (<em>k</em>_d = 1.4 × 10⁹ M^-1 s^-1) to form a dimer radical cation with λ_max at 505 nm which was assigned to the head-to-head bonded dimer radical cation (<strong>3</strong>). The rate constants of the dimer radical cation <strong>3</strong> with <strong>1</strong> (<em>k</em> = 4 × 10⁷ M^-1 s^-1) and with methanol (<em>k</em>_{<em>MeOH</em>} = 5 × 10⁷ M^-1 s^-1) were measured. On the basis of these results together with those of cyclodimers (<strong>2</strong>) the effects of a <em>para</em>-methoxyl substituent on the chemical reactivity of <strong>3</strong> are discussed.</p></div>","PeriodicalId":14262,"journal":{"name":"International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry","volume":"40 2","pages":"Pages 95-99"},"PeriodicalIF":0.0,"publicationDate":"1992-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/1359-0197(92)90064-M","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86682910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiation effects on iodine-doping of pyrolytic graphite films","authors":"T. Matsuyama ,&nbsp;R. Matsushita ,&nbsp;H. Yamaoka ,&nbsp;T. Ohnishi ,&nbsp;K. Tanaka ,&nbsp;T. Nakano ,&nbsp;T. Noguchi ,&nbsp;I. Murase ,&nbsp;M. Hirooka","doi":"10.1016/1359-0197(92)90073-O","DOIUrl":"10.1016/1359-0197(92)90073-O","url":null,"abstract":"<div><p>In order to prepare graphite intercalation compounds of iodine (I₂-GICs), highly-oriented pyrolytic graphite films were irradiated with γ-rays in an iodine-air atmosphere. The depth profile of iodine distribution was examined by means of secondary ion mass spectrometry and X-ray photoelectron spectrometry. The iodine-doping was found to be brought about, though partially, under the influence of γ-rays. The prominent effect of γ-irradiation was the formation of IO₃ on the surface of the graphite films.</p></div>","PeriodicalId":14262,"journal":{"name":"International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry","volume":"40 2","pages":"Pages 151-155"},"PeriodicalIF":0.0,"publicationDate":"1992-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/1359-0197(92)90073-O","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82198531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ultrasonic degradation of alkyl-substituted polysilanes","authors":"Setsuko Irie ,&nbsp;Masahiro Irie","doi":"10.1016/1359-0197(92)90066-O","DOIUrl":"10.1016/1359-0197(92)90066-O","url":null,"abstract":"<div><p>The degradation of poly(methyl-n-propylsilane), poly(di-n-butylsilane) and poly(di-n-hexylsilane) by ultrasonic irradiation has been studied in various solvents. The changes in the optical absorption spectra of the polymer solutions and the molecular weight distributions have been followed as a function of time. Although efficient degradation of poly(methyl-n-propylsilane) was observed in CCl₄, the polymer scarcely decomposed in toluene and cyclohexane. The decrease in the molecular weight was initially rapid but slowed with time and reached a limiting value. The rate of degradation and the limiting chain length were dependent on the size of the substituents. Polysilanes with bulky substituents such as poly(di-n-hexylsilane) and poly(di-n-butylsilane) degradated slower than poly(methyl-n-propylsilane) and the degradation yielded higher limiting molecular weights.</p></div>","PeriodicalId":14262,"journal":{"name":"International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry","volume":"40 2","pages":"Pages 107-110"},"PeriodicalIF":0.0,"publicationDate":"1992-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/1359-0197(92)90066-O","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82513078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Peculiar aspects of the free-radical polymerization of 1-vinylimidazole","authors":"Adolphe Chapiro","doi":"10.1016/1359-0197(92)90063-L","DOIUrl":"10.1016/1359-0197(92)90063-L","url":null,"abstract":"<div><p>The polymerization of 1-vinylimidazole (VI) exhibits several unusual features. The reaction is auto-accelerated in bulk and in solution, an observation attributed to a “matrix” effect. Abnormal orders are found with respect to monomer concentration and to rate of initiation and these are dependent on the monomer content in the reaction mixture. Molecular monomer-monomer and monomer-solvent associations were characterized in these systems, suggesting a gradual change in the reactivity of the monomer upon dilution. A cross-linked gel arises in systems which generate a concentrated polymer solution in the monomer. It is assumed that growing polymer chains can add onto double bonds of the imidazole rings in the polymer but this reaction is slow and only occurs significantly under the conditions stated above. A complicated process takes place when benzoyl peroxide is used to initiate the reaction. A rapid polymerization takes place at very low temperatures leading to low molecular weight polymers and to other addition products. <em>G</em>(R<img>) values were derived from experiments with gamma-ray initiation by combining polymerization rate and molecular weight data. The estimated value for pure VI is <em>G</em>(R<img>)=2.2. The monomer was found to “protect” water and methanol in their radiolysis, being itself “sensitized” by CCL₄.</p></div>","PeriodicalId":14262,"journal":{"name":"International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry","volume":"40 2","pages":"Pages 89-93"},"PeriodicalIF":0.0,"publicationDate":"1992-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/1359-0197(92)90063-L","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88685698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of scission and crosslinking in gamma irradiated butyl rubber","authors":"David J.T. Hill,&nbsp;James H. O'Donnell,&nbsp;M.C. Senake Perera,&nbsp;Peter J. Pomery","doi":"10.1016/1359-0197(92)90070-V","DOIUrl":"10.1016/1359-0197(92)90070-V","url":null,"abstract":"<div><p>Structural changes in butyl rubber (a copolymer of isobutylene and 1.3% isoprene) after γ irradiation in vacuum at 303 and 398 K have been determined by ¹³C-NMR spectroscopy. A variety of new chain-end and crosslink structures have been identified and estimates made of the yields of main-chain scission, <em>G</em>(S), and crosslinking, <em>G</em>(X). Significant dependence of the yields on dose and temperature have been observed. Values of <em>G</em>(S) and <em>G</em>(X) have also been derived from dose dependence of the molecular weight averages <span><math><mtext>M</mtext></math></span>_n, <span><math><mtext>M</mtext></math></span>_w and <span><math><mtext>M</mtext></math></span>_z determined by GPC after irradiation at 77, 195, 303, 348 and 398 K, and are in good agreement with the values derived from the NMR spectra. Radicals formed on isobutylene units by H loss from methyl and methylene groups, and allyl radicals on isoprene units have been observed by ESR spectroscopy, and mechanisms proposed for crosslinking by the formation of H and Y links at the isoprene units.</p></div>","PeriodicalId":14262,"journal":{"name":"International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry","volume":"40 2","pages":"Pages 127-138"},"PeriodicalIF":0.0,"publicationDate":"1992-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/1359-0197(92)90070-V","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85255049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interpenetrating-network formation during electron beam crosslinking of an unsaturated polyester-1,6-hexanediol diacrylate monomer system","authors":"Erzsébet Takács","doi":"10.1016/1359-0197(92)90144-5","DOIUrl":"10.1016/1359-0197(92)90144-5","url":null,"abstract":"<div><p>The progress of electron beam (EB) crosslinking of an unsaturated polyester (UP)-hexanediol diacrylate (HDDA) monomer mixture was monitored by different methods. The gel content measured by solvent extraction was found rather high already at relatively low doses. The physical changes in the system during crosslinking were followed by differential scanning calorimetry (DSC) and dielectric spectroscopy. The DSC results show a shift in T_g with increasing irradiation dose and the beginning of thermal reaction at about 150°C. By irradiation the peaks of the dielectric spectra are broadened and the oscillator strength is reduced. By FTIR analysis it was found that the double bond content of the unsaturated polyester changes only slightly while that of the monomer decreases steeply with the dose. Based on these results the formation of interpenetrating network is probable in the case of UP/HDDA system.</p></div>","PeriodicalId":14262,"journal":{"name":"International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry","volume":"40 1","pages":"Pages 75-79"},"PeriodicalIF":0.0,"publicationDate":"1992-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/1359-0197(92)90144-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73820285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The radiation-induced solid phase graft copolymerization of NMA onto natural silk fabric","authors":"Zhong Guangxiang,&nbsp;Zhuo Dunwen,&nbsp;Jin Xiaoyan","doi":"10.1016/1359-0197(92)90143-4","DOIUrl":"10.1016/1359-0197(92)90143-4","url":null,"abstract":"<div><p>The radiation-induced solid phase graft copolymerization of N-methylolacrylamide (NMA) onto natural silk fabric has been studied using γ-irradiation at room temperature at dose rates from 0.326 to 18.01 kGyḣ^-1 on samples dried naturally and with drying oven at 37–105°C before irradiation. A good straight line which describes the relation between graft rates <em>R</em>_g and dose rates <em>I</em>, <span><math><mtext>R</mtext><msub><mi></mi><mn>g</mn></msub><mtext>/I</mtext><msup><mi></mi><mn><mtext>1</mtext><mtext>2</mtext></mn></msup><mtext>− I</mtext><msup><mi></mi><mn><mtext>1</mtext><mtext>2</mtext></mn></msup></math></span>, was obtained in γ-irradiation on the samples dried with drying oven at 50°C. Radical and ionic polymerization have taken place concurrently on the samples under these conditions. The add-on and the graft rate of NMA on the samples dried with drying oven at 37–50°C are much higher than that of the wet samples. The add-on increases with the dose up to 25 kGy. In certain ranges, the graft rates increase linearly proportionally with the content of NMA and the reciprocal of the moisture in samples. But when NMA content &gt;17% and reciprocal of moisture &gt;75.18, because of the increase of both radiation- and heat-homopolymerization of NMA, the graft rates would gradually decrease. When the room temperature =15–17°C in irradiation, dose rate = 0.326–18.01 kGyḣ^-1, NMA content &lt;17% and moisture =0.93% in samples, the rate of the γ-radiation-induced solid phase graft copolymerization of NMA onto natural silk fabric may be approximately described as following equation: <span><span><span><math><mtext>R</mtext><msub><mi></mi><mn>g</mn></msub><mtext> = 5.882 × 10</mtext><msup><mi></mi><mn>-3</mn></msup><mtext>[</mtext><mtext>M</mtext><mtext>]</mtext><mtext>I</mtext><msup><mi></mi><mn><mtext>1</mtext><mtext>2</mtext></mn></msup><mtext> + 3.209 × 10</mtext><msup><mi></mi><mn>-4</mn></msup><mtext>[</mtext><mtext>M</mtext><mtext>][</mtext><mtext>X</mtext><mtext>]</mtext><msup><mi></mi><mn>-1</mn></msup><mtext>I</mtext></math></span></span></span>.</p></div>","PeriodicalId":14262,"journal":{"name":"International Journal of Radiation Applications and Instrumentation. Part C. Radiation Physics and Chemistry","volume":"40 1","pages":"Pages 71-74"},"PeriodicalIF":0.0,"publicationDate":"1992-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/1359-0197(92)90143-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81807461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}