bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface modification of polymers. I. Vapour phase photografting with acrylic acid
Authors: Allméar K. , Hult A. , Rårnby B. 
Published: April 2003

AbstractSurfaces of low density polyethylene, high density polyethylene, and polystyrene have been modified by grafting with acrylic acid. Benzophenone and acrylic acid in the vapor phase were UV‐irradiated in the presence of a polymer substrate. Grafting with acrylic acid took place in a thin layer on the surface, thus increasing the wettability of the polymer. After 5 min of irradiation, the contact angle against water had decreased to 20° for polystyrene and 50° for the polyethylene samples. ESCA measurements on samples irradiated for 5 min showed a 90% poly(acrylic acid) coverage of the surface for polystyrene, 63% for low density polyethylene, and 56% for high density polyethylene. Acetone or ethanol were used as carriers of monomer and initiator. Acetone was able to initiate grafting and was found to promote and direct grafting to the surface. The stability of the acrylic acid grafted surfaces was studied by contact angle measurements and ESCA. At room temperature, the grafted layer is confined to the surface, but when the material was heated in air the surface was reshaped into a hydrophobic one. The process was reversible. In aqueous surroundings at elevated temperatures the hydrophilic character of the surface was restored.
Synthesis and characterization of BTDA‐based polyamide‐imides
Authors: Dezern James F. 
Published: April 2003

AbstractA series of thermally‐stable, tough, linear polyimides containing amide linkages were prepared. These materials have potential as high temperature films and coatings as well as matrix resins in graphite reinforced structures. The new polyamide‐imides were prepared by reacting a group of isomers of diaminobenzanilide (DABA) with 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (BTDA) to form the polyamide‐acid with subsequent thermal conversion to the polyamide‐imide (PAI). Four polymers were synthesized from unsubstituted amide diamines and two others from N‐substituted amide diamines. The properties of these polyamide‐imides were compared to those of the polyimide of benzophenonetetracarboxylic dianhydride/3,3′‐diaminobenzophenone (LARC–TPI) because their structures are similar, except for the presence of the more flexible amide linkages. These polymers exhibited high inherent viscosities and glass transition temperatures. They were made into tough, flexible films which showed good thermal stability and good resistance to organic solvents. Mechanical properties of the PAI films were better than those of LARC–TPI. Films of the 4,4′‐isomer polyamide‐imide exhibited an exceptionally high modulus and toughness during impact evaluation.
Thermotropic copolyesters. II. Synthesis and characterization of copolyesters containing the bicyclo[2.2.2]oct‐2‐ene mesogenic unit
Authors: Harruna Issifu I. , Polk Malcolm B. 
Published: April 2003

AbstractRandom copolyesters based on 1,4‐benzenedimethanol, trans‐1,4‐cyclohexanedimethanol, and 1,4‐bicyclo[2.2.2]octanedimethanol as spacers in ratios of 2 : 3 of the mesogenic group, bicyclo[2.2.2]oct‐2‐ene‐1,4‐diol were prepared and characterized. The copolyesters containing the 1,4‐benzenedimethanol moiety formed a more brightly colored birefringent fluid in the melt.
Synthesis and properties of aramids and polyarylates having perfluoro‐substituents on the benzene ring
Authors: Kiyotsukuri Tsuyoshi , Tsutsumi Naoto , Okada Kazuya , Asai Kunihiko , Nagata Minoru 
Published: April 2003

AbstractA new series of 16 aramids and 16 polyarylates having perfluoro‐substituents on the benzene ring was prepared by a low temperature solution or an interfacial polycondensation. The effects of fluorine substituents on the structure and properties of polymers were examined. Fluorinated aramids exhibited higher crystallinity, while fluorinated polyarylates show lower crystallinity. The melting point (Tm) of aramids decreased with fluorine substitution, whereas Tm of polyarylates from fluorinated aromatic diols was higher than that of those from unfluorinated ones. The temperature of 10% weight loss and the residue at 900°C decreased with fluorine substitution except for the aramids from fluorinated diamines. Solubility and contact angle also increased with fluorine substitution. Some polyarylates were found to exhibit an optical anisotropy.
Polymer‐supported bases. IX. Synthesis and catalytic activity of polymer‐bound 4‐(1‐pyrrolidino)pyridine moieties
Authors: Tomoi Masao , Ishigaki Satoru , Arita Yasushi , Kakiuchi Hiroshi 
Published: April 2003

AbstractPolystyrene‐bound 4‐(1‐pyrrolidino)pyridine moieties were prepared by the reaction of chloromethylated polystyrene resins with pyrrolidinopyridine derivatives containing hydroxyl groups. The supported amines were effective catalysts for acylations of tert‐alcohols or enols, acylrearrangements, and diester synthesis from epoxides and anhydrides. Some of the low ring‐substituted (8–15%) catalysts exhibited high activity comparable to that of 4‐(N,N‐dimethylamino)pyridine, though the activity was a little lower than that of 4‐(1‐pyrrolidino)pyridine. The recovered catalysts can be re‐used, except for acyl rearrangements, without significant decrease in activity.
Photostabilizing effect of 5‐hydroxy‐3‐phenyl‐amino‐1‐phenyl‐ 3 : 5‐dihydrobenzene derivatives in polychloroprene
Authors: Abdel‐Razik E. A. 
Published: April 2003

AbstractThe photostabilization of polychloroprene in the presence of four derivatives of 5‐hydroxy‐3‐phenylamino‐1‐phenyl‐ 3:5‐dihydrobenzene was studied. The inhibitory activity of the added compounds is proportional to their extinction coefficient values. The addition of singlet oxygen quenchers such as β‐carotene reduces the rate of degradation of polymer solutions. This means that singlet oxygen may involve the photooxidation process. The influence of the most effective stabilizer was also examined using Differential Scanning Calorimeter (DSC) technique; the obtained results indicates the photostabilizing effect of it.
Synthesis and photoinduced memory effect of poly[2‐N‐carbazolylethyl acrylate‐co‐2‐(3,5‐dinitrobenzoyloxy) ethyl methacrylate]
Authors: Hu Chau Jin , Oshima Ryuichi , Arai Yuji , Senō Manabu 
Published: April 2003

AbstractCopolymers containing an intramolecular electron donor‐acceptor (EDA) complex were synthesized by free radical copolymerization of 2‐N‐carbazolylethyl acrylate and 2‐(3,5‐dinitrobenzoyloxy)ethyl methacrylate. Glass transition temperatures show a positive deviation from the weight‐average values of copolymers, indicating the presence of the specific EDA interaction in copolymers in the solid state. Photoinduced “memory effect,” which is defined as the percentage of the difference of the surface potential given by corona charging before and after irradiation of light on polymer films, was 30% for the copolymer with 5 mol% of acceptor content. Memory effect increased to 70% for a 8 μm film by doping with 2 wt% of trichloroacetic acid (TCAA), and leveled off at 5 wt% of TCAA content. Memory effect was also enhanced by increasing the thickness of polymer films and irradiation time. The largest value of memory effect (85%) was obtained from the film of the copolymer with 5 mol% acceptor content doped with 1 wt% TCAA and with thickness larger than 14 μm.
Polymers from nitriles. VII. Polymerization of fumaronitrile with triethylamine as initiator
Authors: Wöuhrle Dieter , Knothe Gerhard 
Published: April 2003

AbstractThe reaction of fumaronitrile with triethylamine in bulk at 295–353 K gives in high yields dark‐colored polymers. The polymerization occurs at one of the two nitrile groups and not at the (CC) double bond. The kinetics of the reaction were investigated and the polymers characterized analytically.
Grafting behavior of copolymers of styrene and ortho‐vinylbenzaldehyde
Authors: Van Ballegooie Peter , Rudin Alfred 
Published: April 2003

AbstractStatistical copolymers of styrene and ortho‐vinylbenzaldehyde (o‐VBA) have been prepared by free radical solution polymerization using azodiisobutyronitrile initiator. Subsequent “grafting from” reactions could be induced through photolytic excitation of the pendant aldehyde carbonyl functionality in the presence of methyl methacrylate monomer; however, actual grafting of polymethylmethacrylate (PMMA) to the copolymer backbone was shown to be quite low (< 6% graft‐on). Another more promising route involved abstraction of labile benzylic hydrogens of the copolymer by chemical methods [e.g., dibenzoyl peroxide or α,α′‐di‐(t‐butylperoxy)diisopropylbenzene] to produce potential graft sites. Graft copolymers prepared by this procedure had PMMA content ranging up to about 30% (by weight), depending upon polymerization conditions. Higher grafting levels were generally observed with increasing reaction temperature and prolonged reaction times. While some grafting evidently originated from the copolymer backbone, the presence of the o‐VBA moiety significantly enhanced the ultimate percent grafting. The resulting multicomponent polymer systems displayed substantial miscibility as evidenced by the transparency of their cast films as well as by their glass transition behavior.
Thermally stable polymers by condensation of diphenols with glyoxal
Authors: Maravigna Pietro 
Published: April 2003

AbstractPolycondensation of bisphenol A, hydroquinone, or dihydroxynaphthalenes with glyoxal using methane sulphonic acid as condensing agent leads to polymeric materials having linear and ladder structure and high thermal stability. These polymers were characterized by NMR and TG. Oligomers (from dimer to tetramer) were isolated by GPC and their structures characterized.
Low surface energy polymers and surface‐active block polymers. III. Adamantyl‐containing polymers
Authors: Hsieh Bing R. , Litt Morton H. 
Published: April 2003

AbstractTwo adamantyl‐containing oxazoline monomers. 2‐(1‐adamantyl)‐2‐oxazoline, A, and 2‐(1‐adamantylmethyl)‐2‐oxazoline, B, were synthesized, and polymerized in 1,2‐dichlorobenzene to give polymers PA and PB respectively. Both polymers are highly crystalline and showed very high Tm's (269°C for PA and 320°C for PB) and little solubility in common organic solvents. Annealed PA showed a critical surface tension of 23.6 dyne/cm. PB was not soluble in the many organic solvents tested at room temperature. Due to its high Tm and insolubility, contact angle measurements on PB were impossible. Diblock copolymers based on different weight ratios of A and 2‐ethyl‐2‐oxazoline, E, showed relatively narrow molecular weight distribution (MWD) when methyl p‐nitrobenzenesulfonate, I, was used as initiator. After annealing, diblock polymers with B/I = 7, 10, or 12 showed Tm's (200–281°C); after quenching the same samples showed Tc's (160–171°C), which were lower than that of pure PB, 215°C. The quenched diblocks showed single Tg's (63–82°C) which implies that these short blocks are compatible. Diblock polymer with B/I = 5 and E/I = 20 was amorphous and displayed inverse emulsifying ability in styrene + water emulsion polymerization. BEB type triblock polymers prepared using ethylene glycol dinosylate as initiator had broader MWD and higher Tm's compared to their diblock counterparts with the same B/E wt% and B/I ratios. These triblock polymers were not completely soluble in styrene and/or water and therefore could not be used as emulsifying agents.
Oligomerization of vinyl monomers. XXI. Characterization of model carbanions of living poly(2‐vinylpyridine) in THF by 7Li‐NMR and conductance: Evidence for the occurrence and nature of triple ion formation
Authors: Khan Ishrat M. , Hogen‐Esch Thieo E. 
Published: April 2003

AbstractThe formation of triple anions is demonstrated by 7Li‐NMR in THF solutions of 1‐lithio‐1‐(2‐pyridyl)ethane, 1‐lithio‐1(3‐methyl‐2‐pyridyl)ethane, and 1‐lithio‐1,3‐di(2‐pyridyl) butane. Good agreement with conductance data was demonstrated in the case of 1. Triple anion formation in the case of 2 was found to be about twice as high as in 1 possibly as a result of the greater charge density on the carbanion in the case of 2.
Spectroscopic studies on the initial stages of thermal degradation of polychloroprene
Authors: Miyata Yoshiaki , Atsumi Masao 
Published: April 2003

AbstractThermal degradation of polychloroprene under nitrogen, especially at the initial stages, has been studied by using 1H‐NMR, 13C‐NMR and FT–IR spectroscopy. A model polymer of low molecular weight (Mn = 6300) was prepared to avoid gelation during degradation. None of isomerized 1,2 unit has been found in the original polymer. Allylic rearrangement of 1,2 unit was the first‐stage reaction, which was finished within 30 min at 150°C. The extent of HCl loss was proportional to the decrease of isomerized 1,2 unit. It has been suggested that the next‐stage reaction is dehydrochlorination of the isomerized 1,2 unit. The presence of terminal vinyl group and the increased amount of olefinic proton were not found in the degraded polymer. The back‐biting mechanism involving a six‐membered cyclization process is proposed for the dehydrochlorination. The thermal racemization has been also found to take place in the 3,4 unit.
Modified cellulose acetate flat membranes for desalination
Authors: Wen‐E Yan , Pu‐Chen Yang , Yi‐Kuan Wang 
Published: April 2003

AbstractIn this article, the radiation grafting of acrylamide on to cellulose acetate flat membranes using UV‐irradiation on the initiator is described. The modified membranes thus obtained have been characterized by IR, DSC, and TGA. Their transport properties have been studied. The modified membranes exhibit higher salt rejection with slightly reduced water flux as compared with cellulose acetate membrane. The work is further extended to study the thermal stability of these modified membranes in a dry state. These modified membranes up to 330°C are stable.
Cationic grafting from carbon black. VIII. Cationic ring‐opening polymerization and copolymerization of oxepane initiated by acylium perchlorate groups on carbon black
Authors: Tsubokawa Norio , Jian Yu , Sone Yasuo 
Published: April 2003

AbstractThe cationic ring‐opening polymerization of oxepane was found to be initiated by carbon black having acylium perchlorate (CO+CIO) groups, which were introduced by the reaction of acyl chloride groups with silver perchlorate. It was confirmed that polyoxepane, i.e., poly(oxyhexamethylene), was propagated from CO+CIO groups on carbon black and effectively grafted on the surface. The rate of the polymerization and the percentage of grafting of poly(oxyhexamethylene) remarkably increased by the addition of epichlorohydrin (ECH) as a promoter: the percentage of grafting in the presence of ECH increased to about 100% with an increase in conversion. Furthermore, CO+CIO groups on carbon black have an ability to initiate the cationic ring‐opening copolymerization of oxepane with ECH to give poly(oxepane‐co‐ECH) with various composition. The ring‐opening copolymerization of oxepane with phthalic anhydride was also initiated by CO+CIO groups to give polyether ester, i.e., poly(hexamethylene phthalate) containing poly(oxyhexamethylene) sequence. In the copolymerization, polyether or polyether ester was effectively grafted from carbon black based on the propagation of these polymers from CO+CIO groups.
The liquid crystalline state of polyimide precursors
Authors: Whang W. T. , Wu S. C. 
Published: April 2003

AbstractThe polyimide precursor poly(4,4′‐methylenediphenylene pyromellitamic acid) (PMDPAA) in N‐methyl pyrrolidone (NMP) was a lyotropic liquid crystal as evidenced by a DSC thermogram and x‐ray spectrum on its gel, and optical properties by the existence of the critical concentration on the solution viscosity. The configuration of PMDPAA as shown by wide angle x‐ray diffraction pattern was composed of regular meta pyromellitamic acid units. These units together with the rigid character of CH2 linkage between two phenyl rings, and the hydrogen bonding of the intermesogenic units were surmised to be the driving force for liquid crystal formation. The liquid crystalline characters were dependent on molecular weight, solid content, temperature, and the extent of mechanical shearing flow. Data from rheometrics mechanical spectrometer (RMS) indicated that the elastic character of the melt of PMDPAA gel at room temperature shifted to lower frequency on standing and the complex dynamic viscosity increased with time.
Synthesis and characterization of silicon‐containing phenylated soluble aramids
Authors: Mohite S. S. , Maldar N. N. , Marvel C. S. 
Published: April 2003

AbstractNew high molecular weight (inherent viscosities, 1.21–0.50 dL/g) aramids having silicon and pendant phenyl groups were synthesized by low temperature interfacial polycondensation technique involving the reaction of acid chlorides: bis(4‐chlorocarbonylphenyl)dimethylsilane and bis(3‐chlorocarbonylphenyl)dimethylsilane with diamines: 2,5‐bis(4‐aminophenyl)‐3,4‐diphenyl‐thiophene and bis(4‐aminophenyl)ether. Copolyamides were obtained by using different proportions of these diamines. All the polymers were completely soluble in organic solvents such as N,N‐dimethylacetamide, N‐methyl‐2‐pyrrolidone, and N,N‐dimethylformamide. Thermal properties were evaluated by thermogravimetry which showed no weight loss below 325°C in both air and nitrogen atmospheres.
Study of photopolymers. XXXIII. Chemical modification of poly(epichlorohydrin) and its application as photosensitive polymers
Authors: Nishikubo Tadatomi , Shimokawa Tsutomu , Fujii Takeshi , Iizawa Takashi , Harita Yoshiyuki , Koshiba Mitsunobu 
Published: April 2003

AbstractHigh Tg. polymers containing both vinyloxy moiety and pendant phthalyl, 2‐thiobenzoxazole or 2‐thiobenzothiazole groups were synthesized by elimination reaction of poly(epichlorohydrin) with potassium hydroxide followed by substitution reaction of the obtained polymer with potassium phthalimide, potassium 2‐thiobenzoxazole or potassium 2‐thiobenzothiazole using tetrabutylammonium bromide as a phase transfer catalyst. The polymers containing vinyloxy moiety and pendant phthalyl or 2‐thiobenzothiazole groups showed high photochemical reactivity and excellent practical photosensitivity as a positive type resist with photo‐generated cationic catalyst such as 2,5‐dibutoxy‐4‐morpholinobenzene diazonium hexafluoroanthimonate. On the other hand, the polymers had high practical photosensitivity and good resolution as a negative type resist with 2,6‐di‐(4′‐azobenzal)‐4‐methylcyclohexanone as a photosensitizer.
Preparation and properties of aromatic polyamides and copolyamides from phenylindanedicarboxylic acid and aromatic diamines
Authors: Yoneyama Masaru , Kuruppu K. D. Athula , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractAromatic polyamides (aramids) having inherent viscosities of 0.5–1.10 dL/g were prepared by the direct polycondensation of 1,1,3‐trimethyl‐3‐(4‐carboxyphenyl)indane‐5‐carboxylic acid with various aromatic diamines using triphenyl phosphite and pyridine as the condensing agents. Copolyamides were also prepared by a similar procedure from a mixture of the phenylindane diacid, terephthalic acid, and p‐phenylenediamine. Almost all of the aramids were soluble in a variety of solvents such as N‐methyl‐2‐pyrrolidone, pyridine, and m‐cresol, and afforded transparent and tough films by the solution casting. These aramids and copolyamides had glass transition temperatures in the range of 290–355°C, and started to lose weight at 340°C in air.
Parylene C at subambient temperatures
Authors: Sharma Ashok K. 
Published: April 2003

AbstractDependence of Parylene C deposition rate on dimer sublimation temperature, inert gas pressure, substrate temperature, and mass of dimer has been investigated. It was found that Parylene C deposition proceeds best at ambient temperature and produces film of optimum performance. Opacity in the film results from its rough morphology and not from the incorporation of the dimer in the film as is normally thought. This was evidenced from scanning electron microscopy and from an estimation of the volatile contents of the Parylene C films. Deposition of Parylene C at liquid nitrogen temperature proceeds via trapping of active monomer species followed by spontaneous polymerization. A quantitative study of the monomer to polymer transition by ESR spectroscopy is presented.
Synthesis and liquid crystalline properties of thermotropic homo‐ and copolycarbonates
Authors: Sato Moriyuki , Kurosawa Katsuya , Nakatsuchi Kazuyasu , Ohkatsu Yasukazu 
Published: April 2003

AbstractNondirect‐type thermotropic homo‐ and copolycarbonates which have flexible spacers between mesogens and carbonate linkages (‐mesogenic unit‐flexible spacer‐carbonate link‐flexible spacer‐) were derived from dihydroxyalkyleneoxy derivatives containing biphenyl, i.e., 4,4′‐bis (ω‐hydroxyalkyleneoxy)biphenyl (Ia and Ib), as mesogens and the structure‐liquid crystallinity relationships were evaluated by thermal analysis and with polarizing microscope.Homopolycarbonates with high molecular weight
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were prepared from (Ia) and (Ib), and alkylene diphenyl dicarbonates (II) by melt polycondensation. The polymers form mesomorphic phases and exhibit linear decrease of phase‐transition temperatures with increment of alkylene spacer lengths without displaying odd‐even number fluctuations. They show lower phase‐transition temperatures and narrower mesomorphic temperature ranges than analogous direct‐type (‐mesogenic unit‐functional group‐flexible spacer‐) biphenyl‐containing polycarbonates \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm OMOC}({\rm O}){\rm O}({\rm CH}_2)_m {\rm OC}({\rm O})\rlap{--})_x $\end{document} and polyesters \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm OMOC}({\rm O})({\rm CH}_2)_m {\rm C}({\rm O})\rlap{--})_x $\end{document}, but have wider temperature ranges than nondirect‐type (‐mesogenic unit‐flexible spacer‐functional group‐flexible spacer‐) biphenyl‐containing polyesters \documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm O}({\rm CH}_2)_n {\rm OMO}({\rm CH}_2)_n {\rm OC}({\rm O})({\rm CH}_2)_m {\rm C}({\rm O})\rlap{--})_x $\end{document}. These results indicate that by the incorporation of alkylene segments between mesogens and carbonate linkages the polymers having reasonable phase‐transition temperatures and wider mesophasic temperature ranges can be obtained. Copolycarbonates
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were prepared from mixtures of (Ib) and 1,4‐bis(2‐hydroxyethyleneoxy)benzene (IV), nonmesogenic moiety, taken in definite molar ratio in feed and (II) (m = 2 and 4). These copolymers except polymers having only nonmesogenic moiety show liquid crystalline mesophases and have wider phase‐transition temperature ranges than the homopolymers. Maximum temperature ranges are observed in the copolymers of composition ratio of 1 : 1. Stable mesophases can be obtained over the entire range of compositions, even though the copolymers contain nonmesogenic units in the backbones.
Kinetic study of the reaction between a hydroxylated polybutadiene and isocyanates in chlorobenzene, III. Reaction with dimer diacid diisocyanate (DDI)
Authors: Coutinho Fernanda M. B. , Rocha Marisa G. 
Published: April 2003

AbstractA kinetic study of the reaction of hydroxylated liquid polybutadiene (M̄n = 2400) R‐45M and dimer diacid diisocyanate (DDI) was carried out in chlorobenzene solution. The kinetic data were compared with the data obtained in a previous work using toluene as solvent. This reaction presented an apparent second order rate law, and was faster in chlorobenzene than in toluene. The accelerating effect of chlorobenzene was higher at higher temperatures.