Angewandte Makromolekulare Chemie最新文献

{"title":"Copolymerization of styrene with butadiene using methyl tert‐butyl ether as active center modifier","authors":"M. Iovu, E. Buzdugan, M. Teodorescu, A. Britchi, G. Hubca, H. Iovu","doi":"10.1002/(SICI)1522-9505(19991101)271:1<18::AID-APMC18>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/(SICI)1522-9505(19991101)271:1<18::AID-APMC18>3.0.CO;2-#","url":null,"abstract":"The copolymerization reaction of styrene with butadiene was performed using n-butyllithium (BuLi) as initiator and methyl tert-butyl ether (MTBE) as active center modifier. The randomness of the copolymers increases with decreasing polymerization temperature and increasing [MTBE]/[BuLi] molar ratio. The solvent and the modifier/initiator ratio strongly influence the copolymerization rate. In comparison with other modifiers, MTBE exhibits a moderate action on rate and selectivity of styrene-butadiene copolymerization. The reaction rate increases as the [MTBE]/[BuLi] molar ratio increases from 7 to 40. At higher [MTBE]/[BuLi] molar ratios, the copolymerization rate decreases. First partial reaction orders with respect to styrene and butadiene were calculated. No transfer reactions were detected in cyclohexane, but these are evident in toluene. The microstructure of the butadiene units incorporated into the copolymer chain is little influenced by the polymerization temperature. Higher [MTBE]/[BuLi] molar ratios will lead to an increase in the number of butadiene units incorporated as vinyl units.","PeriodicalId":7808,"journal":{"name":"Angewandte Makromolekulare Chemie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81015482","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":"Comparison of poly(2,5-dibutoxy-p-phenylenevinylene)s synthesized by two different methods","authors":"H. Xie, Chengyong Liu","doi":"10.1002/(SICI)1522-9505(19990901)270:1<56::AID-APMC56>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/(SICI)1522-9505(19990901)270:1<56::AID-APMC56>3.0.CO;2-#","url":null,"abstract":"Poly(2,5-dibutoxy-p-phenylenevinylene)s (PDBOPVs) were synthesized by two different methods, namely the organosoluble precursor method followed by thermal treatment, and phase transfer catalysis. Both the organosoluble precursor and PDBOPV were characterized by elemental analysis, IR spectrophotometry, UV-Vis spectrophotometry, gel permeation chromatography, thermal gravimetric analysis and differential scanning calorimetry. Factors affecting the synthesis of PDBOPV via the phase transfer catalysis, such as kind and amount of phase transfer catalyst, kind of solvent, reaction time as well as NaOH concentration were studied. Yield, molecular weight, solubility, conductivity and electroluminescent properties of PDBOPVs were compared. The results showed that the yield and solubility of PDBOPV obtained by phase transfer catalysis are higher than those of PDBOPV obtained by the organosoluble precursor method. However, molecular weight, conductivity and electroluminescence of PDBOPV obtained by the organosoluble precursor method are much higher than those of PDBOPV obtained by the phase transfer catalysis method. Conditions for thermal elimination of the organosoluble precursor to improve the electroluminescent properties were also investigated.","PeriodicalId":7808,"journal":{"name":"Angewandte Makromolekulare Chemie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77553818","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":"Electro‐optic birefringence and scattering of concentrated solutions of ethylcellulose","authors":"G. Maitland, O. P. Nwammuo","doi":"10.1002/(SICI)1522-9505(19990701)268:1<1::AID-APMC1>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/(SICI)1522-9505(19990701)268:1<1::AID-APMC1>3.0.CO;2-#","url":null,"abstract":"Photon correlation spectroscopy (PCS) at small scattering vector (kR G ≃ ) and the same is true for the broadening parameters of the decay and rise transients (β r ≃ β d ). The β values were found to decrease with increasing concentration. The experimental results are in qualitative agreement with the theoretical prediction of Doi and Edwards but in quantitative disagreement; thus implying that idealised models are far from describing the true observation. The semi-empirical theory of Douglas and Hubbard aptly described the concentration exponents observed in this work for the zero shear viscosity and the whole chain relaxation data.","PeriodicalId":7808,"journal":{"name":"Angewandte Makromolekulare Chemie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85304493","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":"Photovieillissement d'un copolymère d'éthylène et d'acétate de vinyle en présence de sueur artificielle. II. Evolution morphologique","authors":"C. Dubois, V. Rigny-Bourgeois, A. Chambaudet","doi":"10.1002/(SICI)1522-9505(19990501)266:1<50::AID-APMC50>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/(SICI)1522-9505(19990501)266:1<50::AID-APMC50>3.0.CO;2-#","url":null,"abstract":"Un copolymere d'ethylene et d'acetate de vinyle (EVA) a ete photovielli, en presence de sueur artificielle, dans une cellule amenagee a cet effet. D'autre part, le photovieillissement a ete realise sans sueur artificielle afin d'apprehender le role de ce substrat. Des etudes similaires ont egalement ete conduites sur cet EVA contenant des stabilisants lumiere. L'evolution morphologique des phases cristallines a ete etudiee par calorimetrie differentielle a balayage en suivant, principalement l'evolution des temperatures correspondant aux pics de fusion, et en second lieu celles des temperatures de transitions vitreuses et des enthalpies de fusion. Ainsi, il est possible d'interpreter la reorganisation des deux phases cristallines presentes dans l'EVA neuf, l'une riche en motifs vinyle acetate (VA) et l'autre riche en motifs polyethylene (PE), et de preciser l'action de la temperature, de la photolyse et de la sueur, en presence ou en absence de stabilisants. \u0000 \u0000 \u0000 \u0000An artificial photoaging cell was arranged with the goal to study the behaviour of polymers partly immersed in artificial sweat. A poly(ethylene-co-vinyl acetate) (EVA) was photoaged in this cell. On the other hand, photoaging was realized without artificial sweat in order to understand the action of this substrate. Similar studies were carried out with light stabilized EVA. The morphological evolution of the crystalline structures of the polymer was studied by differential scanning calorimetry, mainly the evolution of the melting temperatures, and secondly those of the glass transition temperatures and of the melting enthalpies. Thus, it was possible to understand the reorganization of two crystalline structures contained in the fresh EVA, the first one rich in poly(vinyl acetate) and the second one in rich in polyethylene.","PeriodicalId":7808,"journal":{"name":"Angewandte Makromolekulare Chemie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89262993","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":"N‐Oxyl‐kontrollierte radikalische Lösungspolymerisation von Styrol","authors":"Marco Drache, A. Koch, G. Schmidt-Naake","doi":"10.1002/(SICI)1522-9505(19990301)265:1<47::AID-APMC47>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/(SICI)1522-9505(19990301)265:1<47::AID-APMC47>3.0.CO;2-#","url":null,"abstract":"The radical solution polymerization (solvent: anisole) controlled by 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) makes possible to synthesize block copolymers with higher molecular weights, as well as to polymerize solid monomers. Polystyrene previously terminated by TEMPO was employed as a macroinitiator, which was then polymerized at various styrene/anisole ratios, temperatures, and initiator concentrations (initiator: dicumyl peroxide). In addition, model calculations were employed to study the initiator-based acceleration and to simulate the product composition of the resulting polymer. The controlled radical polymerizations in solution and in bulk can be performed through dosed initiator addition with comparable rates of polymerization.","PeriodicalId":7808,"journal":{"name":"Angewandte Makromolekulare Chemie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1999-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82247853","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":"Thickness distribution of degradation products during photochemical aging of rigid PVC","authors":"L. Audouin, C. Anton-Prinet, J. Verdu, G. Mur","doi":"10.1002/(SICI)1522-9505(19981201)261-262:1<25::AID-APMC25>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/(SICI)1522-9505(19981201)261-262:1<25::AID-APMC25>3.0.CO;2-#","url":null,"abstract":"The photooxidation of bulk (1 mm) and thin (∼80 μm) samples of unfilled PVC free of photostabilizers was studied in various photoreactors in the 40-70°C temperature range. In bulk samples, the thickness distributions of photoproducts (carbonyls, conjugated polyenes, chain scission, crosslinks) and thermal stabilizer (Zn/Ca stearate) were established using various analytical methods from measurements made on 20 μm microtome slices parallel to the irradiated surface. The experimental results clearly reveal the existence of the following three distinct zones across the sample thickness, starting from the irradiated surface: i) A thin (<100 μm) superficial layer rich in oxidation products and in which chain scissions predominated. ii) A subcutaneous layer extending up to 400 μm depth, containing essentially polyenic species and in which crosslinking predominated. iii) A non degraded core zone beyond about 400 μm depth. During UV exposure, the subcutaneous maximum of polyene concentration moves towards the surface whereas the superficial oxidized layer keeps an almost constant thickness, practically independent of irradiation conditions. These features, and the kinetic data obtained on thin films, are consistent with a mechanistic scheme close to standard one, but in which polyenes (and crosslinks) are generated from alkyl (P°) radicals. These latter can survive at a given distance from the sample surface, because oxidation is diffusion controlled. This behavior is further complicated by the fact that after a certain exposure time the screen effect by the polyene layer takes the control of the thickness distribution of the reactive species.","PeriodicalId":7808,"journal":{"name":"Angewandte Makromolekulare Chemie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87128561","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":"Studies on the aging processes of polymers in electrical systems","authors":"C. Mayoux","doi":"10.1002/(SICI)1522-9505(19981201)261-262:1<143::AID-APMC143>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/(SICI)1522-9505(19981201)261-262:1<143::AID-APMC143>3.0.CO;2-#","url":null,"abstract":"After a definition of electrical systems in which polymers play the role of the insulating material, the macroscopic failures occurring in the polymer under working conditions are presented. Some aspects of aging, like electrical or water treeing, are considered dependent on the morphology and the induced characteristics of the insulating material. The understanding of the aging process of LDPE and XLPE is achieved through the use of original techniques, e.g. electroluminescence, confocal laser scanning microscopy, thermally stimulated crcep. The slow degradation of the polymer characterized by the break of bonds may lead to submicrocracks which coalesce to produce defects of critical sizes. Indeed, it is shown how the presence of gas-filled cavities in the insulating material is one of the causes of breakdown. The synergistic effect of the discharge species impinging on the polymer is prescnted. The discharge activity is cxtended to new insulating materials like poly(ethylene 2,6-naphthalate) (PEN) films. An overview of the rccent models is given in conclusion to point out the needs for a better understanding of the aging mechanisms.","PeriodicalId":7808,"journal":{"name":"Angewandte Makromolekulare Chemie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91073832","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":"Inverse microemulsion polymerization of acrylamide in the presence of N,N-dimethylacrylamide","authors":"V. Juraničová, Sakurako Kawamoto, K. Fujimoto, H. Kawaguchi, J. Barton̆","doi":"10.1002/(SICI)1522-9505(19980801)258:1<27::AID-APMC27>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/(SICI)1522-9505(19980801)258:1<27::AID-APMC27>3.0.CO;2-#","url":null,"abstract":"The presence of N,N-dimethylacrylamide (NDA) influences the stability of initial, clear, single-phase Winsor IV inverse microemulsion composed of toluene/AOT (sodium salt of bis(2-ethylhexyl) sulfosuccinate)/NDA/water/acrylamide (AAm). For a molar fraction of NDA, nNDA = [NDA]/([NDA] + [AAm]) = 0.200 a single-phase system turned to a milky one during polymerization initiated by oil-soluble dibenzoyl peroxide or water-soluble ammonium peroxodisulfate, and finally a two-phase system was formed. For nNDA values greater than 0.200 also the precipitation of a polymeric product was observed during polymerization. The (co)polymerization rate of AAm and NDA exponentially decreases with increasing value of nNDA, while the reverse is true for the (co)polymer particle diameter. The results support the idea of simultaneously proceeding free-radical polymerization initiated by free radicals in continuous oil and dispersed water phase of the inverse microemulsion system. \u0000 \u0000 \u0000 \u0000Die Gegenwart von N,N-Dimethylacrylamid (NDA) beeinflust die Stabilitat von klaren, einphasigen inversen Winsor-IV-Mikroemulsionen aus Toluol/AOT (Natriumsalz von Bis(2-ethylhexyl)sulfosuccinat)/NDA/Wasser/Acrylamid (AAm). Wahrend der durch lipophiles Benzoylperoxid oder hydrophiles Ammoniumperoxodisulfat initiierten Polymerisation wird das klare Ein-Phasen-System bei einem NDA-Molanteil von nNDA = [NDA]/([NDA] + [AAm]) = 0.200 milchig trub und bildet schlieslich ein Zwei-Phasen-System. Bei nNDA-Werten uber 0.200 fallt wahrend der Polymerisation auch eine polymere Substanz aus. Die (Co)Polymerisationsgeschwindigkeit von AAm und NDA nimmt exponentiell mit steigendem nNDA-Wert ab, wahrend der Durchmesser der (Co)Polymerteilchen wachst. Diese Ergebnisse stutzen die These einer simultan verlaufenden Radikalkettenpolymerisation, die durch freie Radikale in einer kontinuierlichen Ol- und einer dispergierten wasrigen Phase des inversen Mikroemulsionssystems initiiert wird.","PeriodicalId":7808,"journal":{"name":"Angewandte Makromolekulare Chemie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78915334","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":"Hydrophilic PVC composite films obtained by in situ polymerization, 1 : Swelling studies","authors":"C. Simionescu, Carmen Topor","doi":"10.1002/(SICI)1522-9505(19980601)257:1<31::AID-APMC31>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/(SICI)1522-9505(19980601)257:1<31::AID-APMC31>3.0.CO;2-#","url":null,"abstract":"In order to introduce a monomer into a PVC matrix, the swelling behavior of PVC films was tested in four solvents (acetone, methyl ethyl ketone, benzene, and toluene) and in acrylic acid solutions in acetone (10, 25 and 50 wt.-%) containing 0.1 wt.-% azoisobutyronitrile. The type of transport, diffusion and permeation coefficients, sorption kinetics and Arrhenius parameters are discussed.","PeriodicalId":7808,"journal":{"name":"Angewandte Makromolekulare Chemie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87569106","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":"New method for predicting lifetime of seals from compression-stress relaxation experiments","authors":"K. Gillen, M. Keenan, J. Wise","doi":"10.1002/(SICI)1522-9505(19981201)261-262:1<83::AID-APMC83>3.0.CO;2-#","DOIUrl":"https://doi.org/10.1002/(SICI)1522-9505(19981201)261-262:1<83::AID-APMC83>3.0.CO;2-#","url":null,"abstract":"Interpretation of compression stress-relaxation (CSR) experiments for elastomers in air is complicated by (1) the presence of both physical and chemical relaxation and (2) anomalous diffusion-limited oxidation (DLO) effects. For a butyl material, the authors first use shear relaxation data to indicate that physical relaxation effects are negligible during typical high temperature CSR experiments. They then show that experiments on standard CSR samples ({approximately}15 mm diameter when compressed) lead to complex non-Arrhenius behavior. By combining reaction kinetics based on the historic basic autoxidation scheme with a diffusion equation appropriate to disk-shaped samples, they derive a theoretical DLO model appropriate to CSR experiments. Using oxygen consumption and permeation rate measurements, the theory shows that important DLO effects are responsible for the observed non-Arrhenius behavior. To minimize DLO effects, they introduce a new CSR methodology based on the use of numerous small disk samples strained in parallel. Results from these parallel, minidisk experiments lead to Arrhenius behavior with an activation energy consistent with values commonly observed for elastomers, allowing more confident extrapolated predictions. In addition, excellent correlation is noted between the CSR force decay and the oxygen consumption rate, consistent with the expectation that oxidative scission processes dominate the CSR results.","PeriodicalId":7808,"journal":{"name":"Angewandte Makromolekulare Chemie","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1998-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86217509","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}