bluuebunny/crossref_metadata_2025 huggingface dataset:
The mechanisms of thermal degradation of polymethyl acrylate using pyrolysis gas chromatography mass spectrometry
Authors: Gunawan L. , Haken J. K.
Published: April 2003

The pyrolysis of polymethyl acrylate is reported with identification of the major pyrolysis products. The mechanism involving random homolytic scission of the chain followed by a series of intermolecular and intramolecular transfer reactions as proposed by Cameron and Kane and extended by Haken, Ho, and Houghton is further developed. Reaction mechanisms are postulated for all of the products produced and ion fragmentation mechanisms for the various spectra produced are shown. The paper also forms the basis for a study of the homologous alkyl polyacrylates, both straight and branched chain esters being considered these having not been previously extensively studied.
Introduction of hydrophilicity of polyacetylene film surfaces
Authors: Guiseppi‐Elie Anthony , Wnek Gary E.
Published: April 2003

Polyacetylene films have been rendered hydrophilic by treatment with aqueous KMnO4. The treated films were characterized by contact angle measurement, infrared spectroscopy, and x‐ray photoelectron spectroscopy. We found that it is possible to lower the contact angle of H2O on polyacetylene from 72° to ca. 10° without significantly affecting the electrical conductivity afforded after I2 doping compared with similar doping of untreated films. The treated, hydrophilic films were found to be more permeable to aqueous ionic solutions than pristine polyacetylene.
Vinyl polymerization of acrylamide initiated by Thallium(III) ions in solution
Authors: Misra Sivananda , Sahu Gangadhar
Published: April 2003

Kinetics of polymerization of acrylamide initiated by Thallium(III) perchlorate was investigated in aqueous perchloric acid medium in the temperature range of 55–70°C. The rates of polymerization were measured varying the concentration of the monomer, initiator, and perchloric acid. The rate of polymerization was found to increase with increase of temperature, monomer concentration, initiator concentration, and perchloric acid concentration. The effect of additives like different solvents, surfactants, and retarders on the rate of polymerization was studied. Molecular weights of the polymer were determined by viscometry. The chain transfer constants for the monomer (CM) and that for the solvent dioxan (Cs) were calculated to be 7.33 × 10−3 and 6.66 × 10−3, respectively. From the Arrhenius plot, the overall activation energy (Ea) was calculated to be 10.68 kcal/mol. The energy of initiation was calculated to be 12.36 kcal/mol. Depending on the results obtained, a suitable reaction mechanism has been suggested and a rate equation has been derived.
Poly(bismethylene hydroquinone) (PBHQ). I. Synthesis and characterization
Authors: Dalal V. F. , Litt M. H. , Rickert S. E.
Published: April 2003

Poly(bismethylene hydroquinone) (PBHQ) has been synthesized. Fourier transform infrared, 13C solid‐state CP/MAS NMR and elemental analysis provide strong evidence of two methylene bridges per hydroquinone molecule. The polymer was (1) air oxidized using ammonia and (2) chemically oxidized using bromine/KOH. The initial structure and oxidation process was studied by comparison of the unoxidized and oxidized polymers using Fourier transform infrared, elemental analysis, and 13C solid‐state CP/MAS NMR.
A kinetic model for predicting oxidative degradation rates in combined radiation‐thermal environments
Authors: Gillen Kenneth T. , Clough Roger L.
Published: April 2003

The complex degradation behavior of a poly(vinyl chloride) (PVC) cable jacketing material in combined radiation/temperature/air aging environments is experimentally separated into two dominant radiation dose‐rate effect mechanisms. The first, operative at high dose rates, involves diffusion‐limited oxidation, which leads to heterogeneously oxidized samples. The second, important at low dose rates, involves thermally‐induced breakdown of intermediate peroxides. In the homogeneous degradation regime, a theoretical kinetic model is derived which, based on experimental evidence, assumes unimolecular termination kinetics and rate‐determining, hydroperoxide‐mediated branching reactions. Dependent upon the ratio of particular rate constants, the model predicts that dose‐rate effects will either continue to increase or eventually disappear as the dose rate is lowered. Theoretical analysis of sequential (radiation followed by temperature exposures) aging experiments allows a time–temperature–dose rate shifting procedure to be developed. Using this procedure, higher temperature combined environment results can be shifted to a lower reference temperature, thereby extending the lower temperature results to lower (and experimentally inaccessible) dose rates. By applying this procedure to experimental PVC data, evidence in support of the theoretical model is obtained. In addition, model predictions are shown to agree with 12‐year real‐time aging results.
Synthesis, characterization, and complexing properties of a polymethacrylate bearing pendant macroheterocyclic structures
Authors: Herweh J. E.
Published: April 2003

The synthesis of a polymerizable methacrylate bearing the dibenzo‐18‐crown‐6 moiety (5) was effected in three steps by condensation of 3,4‐dihydroxybenzaldehyde with 1,2‐bis[2′‐(2″‐chloroethoxy)ethoxy]benzene (2), reduction of the resulting 4‐formyldibenzo‐18‐crown‐6 (3) to 4 and subsequent reaction of 4 with methacryloyl chloride. The methacrylate (5) was polymerized in solution using 2,2′‐azobis(isobutyronitrile) (AIBN) as the initiator and gave a solid polymer (6) having a midrange Tg of 67°C. The polymethacrylate bearing pendant crown‐ether structure (6) was found to effectively complex potassium ions and was clearly more effective in its complexing ability than dibenzo‐18‐crown‐6 (7) or a polyurethane bearing the dibenzo‐18‐crown‐6 moiety (8) in the polymer backbone. The subject polymer (6) was also found to complex and consequently solubilize several metal 7,7,8,8‐tetracyanoquinodimethane (TCNQ) salts to give semiconducting compositions. Evidence is given that in the presence of the neutral acceptor molecule, 2,3‐dichloro‐5,6‐dicyano‐1,4‐benzoquinone (DDQ), the polymethacrylate (6) acting as a donor, gives rise to a charge‐transfer (C/T) complex.
Polyamides from 2,6,(7)‐diamino‐9,10‐dihydro‐9,10‐ethanoanthracene and 2,6,(7)‐diaminoanthracene
Authors: Frazer A. H. , Anderson B. C. , Garver L. C. , Fukunaga T.
Published: April 2003

High‐molecular‐weight, film‐forming, amorphous polyamides have been prepared from 2,6(7)‐diamino‐9,10‐dihydro‐9,10‐ethanoantracene with adipic, sebacic, dodecanoic, isophthalic, 4,4′‐oxybibenzoic, 2,6‐naphthoic, 4,4′‐bibenzoic, and terephthalic acid. Thermal elimination of ethylene from these polymers has yielded the corresponding polyamides from 2,6(7)‐diaminoanthracene which were of high molecular weight, film forming, and crystalline.
A contribution to the theory of accelerated sulphur vulcanization of natural rubber and polybutadiene BR with tetramethyl thiuram disulphide and bis(2‐benzothiazolyl) disulphide
Authors: Huson M. G. , McGill W. J. , Wiggett R. D.
Published: April 2003

A number of simple natural rubber (NR) and polybutadiene (BR) formulations were vulcanized in a differential scanning calorimeter. From the shapes of the exothermal cure curves the interaction of curatives can be examined. It is suggested that polysulphidic‐accelerator‐terminated pendent groups could either crosslink, or be chelated with zinc ions. The latter reaction allows interaction with accelerator molecules to reform the unchelated pendent group, and a zinc accelerator complex, that, in turn, can react with sulphur and rubber molecules to give pendent groups. Differences in the behavior of NR and BR are attributed to the relative rates of these two reactions in the elastomers. Bis(2‐benzothiazolyl) disulphide does not react with zinc, and it is suggested that it coordinates with the zinc dithiolate accelerator complex, increasing its activity.
On the synthesis and polymerization of t‐butyl‐p‐vinylperbenzoate and the grafting of its homo‐ and copolymers
Authors: Schaefers Klaus , Schneider Christel
Published: April 2003

The monomer initiator t‐butyl‐p‐vinylperbenzoate (TBVP) was synthesized and its homo‐ and copolymerization with styrene, methacrylonitrile, isoprene and phenylmethacrylate was investigated. TBVP is preponderantly incorporated in all four systems; values of Q = 2.27 and e = −0.13 characterize TBVP as a weak donor with a high monomer reactivity. Kinetic considerations show that all propagation steps in which TBVP takes part are faster or at least as fast as the self‐propagation steps of the comonomers used. Rate constants and activation energies of the thermal decomposition of poly(t‐butyl‐p‐vinylperbenzoate) and poly(t‐butyl‐p‐vinylperbenzoate‐co‐styrene) were determined. The polymer initiators were used for grafting experiments with styrene, acrylonitrile, and methyl methacrylate. The data evaluated for the grafting efficiency, the success of grafting, and the degree of grafting show that these polymers of p‐vinylperbenzoate are efficient initiators.
Reduction in the moisture absorption of cured MY720/DDS epoxy resins
Authors: Fisher C. M. , Gilbert R. D. , Fornes R. E. , Memory J. D.
Published: April 2003

Thin films of cured MY720/DDS epoxy resins were treated with blocking reagents for hydroxyl, amine, and epoxide functional groups. Infrared spectroscopy (IR) and differential scanning calorimetry (DSC) were used to monitor the progress of the reaction. Treated films were soaked in distilled water at 30°C for 720 h, and the corresponding moisture absorption determined gravimetrically. Samples treated with N‐methyl‐N‐t‐butyldimethylsilyl trifluroacetamide (MTBSTFA) containing 1% t‐butyldimethylchlorosilane (TBDMCS) in dimethylsulfoxide (DMSO) at 30°C showed a maximum reduction in the IR peak at 3400 cm−1 (OH and NH) of 39% and a 100% reduction in the epoxide peak at 904 cm, −1. The moisture absorption was 1.9%, a reduction of 58% compared to the untreated films (ca. 4.5%). The reactions show dependencies on time and temperature and are diffusion controlled. Samples treated with trimethylsilyl isocyanate (TMSI) in DMSO a 70°C showed 72% reduction in the 3400 cm−1 IR peak; DSC thermograms do not show an exothermic energy, suggesting that all epoxide groups reacted. These reactions are primarily dependent on time and temperature. The moisture absorption of TMSI treated samples was 1.0% (75% reduction). Samples were also treated with m‐trifluoromethyl phenyliscyanate (MTFPI). The reduction in the IR peak at 3400 cm−1 was 9%, but the moisture absorption was 2.4%—a reduction of 47%.
Cationic ring‐opening polymerization of 1,4‐anhydro‐2,3‐di‐O‐benzyl‐α‐L‐arabinopyranose and synthesis of L‐arabinofuranan
Authors: Koyama Yoshiyuki , Harima Kazunari , Matsuzaki Kei , Uryu Toshiyuki
Published: April 2003

1,4‐Anhydro‐2,3‐di‐O‐benzyl‐α‐L‐arabinopyranose (=1,5‐anhydro‐2,3‐di‐O‐benzyl‐β‐L‐arabinofuranose) (ABAP) was synthesized and underwent cationic ring‐opening polymerization with several kinds of Lewis acids. All the polylmers prepared by Lewis acids as catalyst were found to consist of two different structural units, α‐furanosidic and β‐furanosidic units, and the structure of the polymers greatly depended on the polymerization conditions. Polymerization of ABAP with antimony pentachloride catalyst at 0°C for 42 h gave a polymer with the highest α content of 93%, and that at −20°C for 3 h gave a polymer with the lowest (25%) α content. The other catalysts such as phosphorus pentafluoride, boron trifluoride etherate, niobium pentafluoride, and tantalum pentafluoride also afforded polymers with mixed structure of α‐and β‐furanosides. After debenzylation of poly(ABAP), a new polysaccharide, L‐arabinofuranan was obtained.
Direct polycondensation with tosyl chloride in pyridine by formamide catalyzed alcoholysis
Authors: Higashi Fukuji , Mashimo Toshio
Published: April 2003

The reaction with tosyl chloride was significantly promoted by controlling alcoholysis with bisphenols in the presence of catalytic amounts of formamides to give aromatic polyesters with high molecular weights from aromatic dicarboxylic acids and bisphenols. Mechanistic features of the reaction were studied by use of various formamides and other arylsulfonyl chlorides, as well as by varying the addition mode of bisphenols and changing the relative amount of formamide. The reaction was successfully applied to the preparation of aromatic polyesteramides with high molecular weights from aromatic dicarboxylic acids, bisphenols, and diamines, but with limited success to that of polyamides.
Binding of anthraquinone dyes by polyion complexes consisting of a piperidinium cationic polymer and various polyanions in aqueous solution
Authors: Takagishi Toru , Kuroki Nobuhiko , Kozuka Hiroshi , Mitsuishi Masaru
Published: April 2003

The extent of binding of 1‐amino‐4‐alkylaminoanthraquinone‐2‐sulfonates (alkylmethyl, ethyl, propyl, and butyl), which have different chemical structures from methyl orange derivatives, by polyion complexes consisting of a piperidinium cationic polymer and various polyanions such as sodium poly acrylate, poly methacrylate, poly styrenesulfonate, carboxymethylcellulose, and dextran sulfate, was measured in an aqueous solution. The effect of alkyl group of the anthraquinone dye on the binding behavior was investigated. Also, the resultant binding characteristics were compared with those previously observed with methyl orange and its homologs. These polyion complexes exhibited very strong binding affinity toward the anthraquinone dye. The polyion complex of the polycation and sodium poly styrenesulfonate bound the dye noncooperatively and the binding process was athermal. The first binding constant accompanying the binding is of the order of 105–106. In contrast, the polyion complexes composed of the polycation and the other polyanions exhibited strong cooperative binding and the binding process was exothermic. The possible mode of binding is discussed.
Rate constants in the photopolymerization of H2O2–isoprene systems
Authors: Chang J. F. , Chang T. C. , Ho S. Y.
Published: April 2003

The polymerization reactions of isoprene with the use of H2O2 as the photoinitiator have been studied in acetone solutions. The lifetime of chain radicals, τs, was evaluated to be 0.29 by the rotating sector technique. The rate constants kp and kt were found to be 19.1 and 3.40 × 107 L/mol‐ s, respectively.
Effect of polycondensation methods on molecular weight distribution of nylon 610
Authors: Arai Yumi , Watanabe Masayoshi , Sanui Kohei , Ogata Naoya
Published: April 2003

Polycondensation methods greatly influence the molecular weight distribution of poly(hexamethylene sebacamide) (nylon 610) as determined by gel permeation chromatography (GPC). The ratio of weight average molecular weight to number average molecular weight (Mw/Mn) was used as a measure for estimating the molecular weight distribution. The Mw/Mn ratios of nylon 610 obtained from melt, solid phase, and high temperature polycondensation methods were 2 to 3.5, which were expected values for the most probable distribution. However, those for polymers obtained from the direct polycondensation in the presence of triphenylphosphine, interfacial polycondensation and low temperature polycondensation using an acid chloride varied over a wide range from 3.5 to 8.5. The effect of the kind of organic solvents in the interfacial method on the Mw/Mn ratios was especially large, and the molecular weight distribution could be controlled to some extent by selecting an appropriate solvent.
Oxoaminium salts as initiators for cationic polymerization of vinyl monomers
Authors: Yoshida Eri , Nakamura Kazuaki , Takata Toshikazu , Endo Takeshi
Published: April 2003

Oxoaminium salt (1), derived from 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO, 2) by one‐electron oxidation, could be an initiator for cationic polymerization of vinyl monomers such as isobutyl vinyl ether (IBVE), 2,3‐dihydrofuran, p‐methoxystyrene, N‐vinyl pyrrolidone, etc., to give the corresponding polymers, when 1 had a low nucleophilic counter anion. Formation of the adducts of 1 and IBVE as well as 1H‐NMR and IR data suggested the formation of polymers containing NOC structure as the polymer head group. In the polymerization of IBVE, the effects of solvent and concentration of 1 were little observed, however the polymerization rate was dependent on temperature. Furthermore, the thermal reaction of the polymers obtained, which were regarded as prepolymers for block copolymerization and polymeric initiators for radical polymerization, was studied. For example, poly(2‐benzylidene‐1,3‐dioxane) obtained by the polymerization of 2‐benzylidene‐1,3‐dioxane with oxoaminium hexafluoroantimonate (1, X = SbF6) was employed as an initiator for radical polymerization of MMA to give its block copolymer with PMMA. © 1993 John Wiley & Sons, Inc.
Preparation and properties of new aromatic polyamides from bis(4‐aminophenyl) phenylphosphine and aromatic dicarboxylic acids
Authors: Yamashita Mitsuhiro , Kakimoto Masa‐Aki , Imai Yoshio
Published: April 2003

A new triphenylphosphine‐type monomer, bis(4‐aminophenyl) phenylphosphine, was synthesized starting from p‐bromoaniline and dichlorophenylphosphine. The aromatic polyamides (aramids) containing triphenyphosphine unit in the polymer backbone was prepared by the polycondensation of this diamine with various aromatic diacid chlorides using a low‐temperature solution method in N,N‐dimethylacetamide (DMAc). The aramids having inherent viscosities of 0.4–0.7 dL/g were obtained in quantitative yields. The polymers were amorphous and soluble in various organic solvents such as DMAc, N‐methylpyrrolidone, dimethyl sulfoxide, pyridine, and m‐cresol. Transparent, tough, and flexible films were obtained by casting from the DMAc solutions. The glass transition temperatures of the aramids were in the range of 265–310°C, and the 10% weight loss temperatures were above 400°C in air. © 1993 John Wiley & Sons, Inc.
Multifunctional coupling agents for living cationic polymerization. I. Sodiomalonate anions for vinyl ethers
Authors: Fukui Hiroji , Sawamoto Mitsuo , Higashimura Toshinobu
Published: April 2003

A series of multifunctional malonate anions, [Na⊕⊖C(COOEt)2CH2]mC6H6−m(I; m = 2–4), were examined as polymer coupling agents for the living cationic polymerization of vinyl ethers initiated with the hydrogen iodide/zinc iodide (HI/ZnI2) initiating system. The bifunctional anion (2;I, m = 2), 1,4‐[Na⊕⊖C(COOEt)2CH2]2C6H4, terminated living polymers of isobutyl vinyl ether (IBVE) (DPn = 10) almost quantitatively in toluene at −15°C to give coupled living polymers with doubled molecular weights in 96% yield; the dianion 2 was dissolved in tetrahydrofuran containing 18‐crown‐6 for maintaining the solution homogeneous. The yield of the coupled polymers was increased with shorter living chains or in less polar solvents. Also by coupling via 2, ABA block copolymers were obtained from living AB block polymers of IBVE and an ester‐functionalized vinyl ether (CH2CHOCH2CH2OCOCH3). Coupling of living poly(IBVE) with the trifunctional anion (3; I, m = 3) led to tri‐armed polymers in 56% yield, whereas with the tetrafunctional version (4; I, m = 4), only three out of the four anions reacted to give another tri‐armed polymer in 85% yield. © 1993 John Wiley & Sons, Inc.
Polymer‐supported Ziegler–Natta catalyst for the polymerization of isoprene
Authors: Ran Ruicheng
Published: April 2003

A polymer‐supported Ziegler–Natta catalyst, polystyrene‐TiCl4AlEt2Cl (PS–TiCl4AlEt2Cl), was synthesized by reaction of polystyrene–TiCl4complex (PS–TiCl4) with AlEt2Cl. This catalyst showed the same, or lightly greater catalytic activity to the unsupported Ziegler–Natta catalyst for polymerization of isoprene. It also has much greater storability, and can be reused and regenerated. Its overall catalytic yield for isoprene polymerization is ca. 20 kg polyisoprene/gTi. The polymerization rate depends on catalyst titanium concentration, mole ratio of Al/Ti, monomer concentration, and temperature. The kinetic equation of this polymerization is:Rp=k[M]0.30[Ti]0.41[Al]1.28, and the apparent activation energy ΔEact= 14.5 kJ/Mol, and the frequency factorAp= 33 L/(mol s). The mechanism of the isoprene polymerization catalyzed by the polymer‐supported catalyst is also described. © 1993 John Wiley & Sons, Inc.
Study of bulk chain coupling reactions. II. Reaction between bisoxazolones and amine‐terminated polyether: Synthesis of polyether‐block‐polyamides
Authors: Acevedo Margarita , Fradet Alain
Published: April 2003

The bulk reactions between 2,2′‐bis(4,4‐dimethyl‐5(4H)‐oxazolone) (B3) or 2,2′‐(1,2‐ethylene)‐bis(4,4‐dimethyl‐5(4H)‐oxazolone) (B4) and amine‐terminated polyether (Jeffamine ED‐900) have been studied by SEC, and 1H‐and 13C‐NMR and the resulting polymers were characterized by DSC and TGA. These chain coupling reactions have been applied to the synthesis of polyether‐block‐polyamides, starting from mixtures of amineterminated polyether and polyamide‐12. High molar mass block copolymers were synthesized in the bulk within 1 h at 200°C and under atmospheric pressure, instead of several hours at 240°C under vacuum for the usual reaction between dicarboxy polyamides and dihydroxy polyethers. No other side reactions than the formation of a very small amount of 2‐imidazolin‐5‐ones has been found. The DSC studies of block copolymers show the existence of a phase separation between the soft (polyether) and hard (polyamide) blocks. © 1993 John Wiley & Sons, Inc.
Liquid crystal‐forming aqueous hydroxypropyl cellulose solutions: Effects of surfactants on the turbidity and shear viscosity
Authors: Suto Shinichi , Iwasawa Ichisuke
Published: April 2003

The effects of type and concentration of surfactant on the turbidity and viscometric behavior for dilute and concentrated aqueous hydroxypropyl cellulose (HPC) solutions were examined. Two anionic surfactants, sodium dodecyl benzene sulfonate (SDBS) and sodium dodecyl sulfate (SDS), caused the cloud point of the dilute system to increase, but a nonionic and two cationic surfactants did not do so markedly. The transmittance for the dilute system increased with surfactant. The transmittance and viscometric behavior for the concentrated system were strongly dependent on the phase of the system: In the single‐phase (isotropic and anisotropic), the transmittance and viscosity increased with SDBS, but, in the biphasic region, the behaviors were not as simple. An attempt was made to explain the transmittance and viscometric behavior in the single‐phase on the basis of the change in apparent molecular weight and in order of HPC molecules. The phase transformation appeared to become less sensitive to temperature with SDBS. © 1993 John Wiley & Sons, Inc.
Synthesis and evaluation of polyimides derived from spirobisindane dietheranhydride
Authors: Chao Herbert S.‐I. , Barren Elizabeth
Published: April 2003

Polyimides derived from 5,5′‐[(2,2′,3,3′‐tetrahydro‐3,3,3′,3′‐tetramethyl‐1,1′‐spirobi[1H‐indene]‐6,6′‐diyl)bis(oxy)]bis‐1,3‐isobenzofurandione (spirobisindane dietheranhydride, SBIDA) and 20 plus aromatic diamines were prepared. The weight percentage of cyclic contaminants in each polyimide, estimated by gel permeation chromatography, ranges from 4 to 25%. The amount of cyclics formed in each polyimide depends on the distance and spatial orientation of the two amino groups on the aromatic diamines as well as the rigidity of the diamines. The formation of SBIDA‐containing polyimide was found to be catalyzed by alkali metal ions even when the reaction was conducted in m‐cresol. Thermal stability and glass transition temperature of those SBIDA‐derived polyimides were examined with thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). Two promising compositions were scaled up and their mechanical properties were obtained. © 1993 John Wiley & Sons, Inc.
One‐step polymerization of polytrithiocarbonate using phase‐transfer catalyst
Authors: Leung Louis M. , Chan W. H. , Leung Sew Koo
Published: April 2003

A series of aliphatic and aromatic polytrithiocarbonates was prepared using a novel “one‐pot” synthesis procedure employing a phase‐transfer catalyst. The starting reagents were either an aliphatic or an aromatic dihalide and an excessive amount of carbon disulfide. The effects of the phase‐transfer catalyst and reaction conditions on yield were studied. The structure and composition of the polymers and reaction side‐products were determined from infrared, ultraviolet, 1H‐NMR spectra, and elemental analyses. The polymers were further characterized by viscosity measurement and thermal analysis. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of novel photopolymerizable multifunctional 2‐propenyl ether analogues
Authors: Crivello James V. , Suh Dong‐Hack
Published: April 2003

Monomers bearing two, three, four, and six cationically polymerizable aryl 2‐propenyl groups were synthesized and characterized. These compounds can be readily prepared by the catalytic isomerization of the corresponding allyl compounds. Strong bases and tris(triphenylphosphine)ruthenium(II) dichloride were used as the catalysts for these isomerizations. A study of the cationic photopolymerizations of these novel monomers was carried out using a diaryliodonium salt photoinitiator. The polymerization involves a stepwise condensation of the monomers followed by an intramolecular ring closure to form polyindanes. The resulting photopolymerized polymers underwent thermal oxidative decomposition at temperatures over 430°C. © 1993 John Wiley & Sons, Inc.
Preparation of amphiphilic polyisobutylenes‐b‐polyethylenamines by mannich reaction. I. Synthesis and characterization of α‐phenololigoisobutylenes
Authors: Jamois Didier , Tessier Martine , Maréchal Ernest
Published: April 2003

The cationic polymerization of isobutylene initiated by 4‐(2‐hydroxy‐2‐propyl)phenol/BCl3 system results mainly in α‐phenol‐ω‐chlorooligoisobutylene; however p‐(2‐chloro‐2,4‐dimethyl‐4‐pentyl)phenol is present in all cases. α‐Methyl‐ω‐chlorooligoisobutylene is formed only when the temperature is below−50°C; it results from initiation by the phenol/BCl3 system. Thermal dehydrochlorination of α‐phenol‐ω‐chlorooligoisobutylene is quantitative and leads to a mixture of isomeric ω‐unsaturated oligoisobutylenes. α‐Methyl‐ω‐phenololigoisobutylene is prepared by the Friedel—Crafts reaction between industrial unsaturated oligoisobutylene and phenol in the presence of SnCl4 at −30°C; the reaction is quantitative between −50 and −30°C degradation takes place. © 1993 John Wiley & Sons, Inc.
Phase behavior of pseudo‐IPN's of polycarbonate‐urethane and polystyrene
Authors: Frisch H. L. , Zhou Peiguang
Published: April 2003

The pseudo‐IPN's of PCU/PS with different Mn and narrow MWD of the linear PS have been synthesized and characterized. The effect of Mn and composition on the phase morphology of the pseudo‐IPN's of PCU/PS has been studied by DSC and SEM. The pseudo‐IPN's with ultra‐high Mn of the linear PS appeared to possess a single Tg and no SEM‐resolvable domains at 35 wt % PS and below. This metastable state may reflect the result of a high extent of entanglement of the linear PS chains with the PCU network and the limited molecular mobility of the linear PS chains with high Mn. © 1993 John Wiley & Sons, Inc.
Synthesis and thermooxidative stability of poly[1,4‐phenylene‐4,4′‐(2,2,2‐trifluoro‐1‐phenylethylidene)bisphthalimide] and other fluorinated polyimides
Authors: Scola Daniel A.
Published: April 2003

The synthesis of a novel polyimide (3F‐PDA) derived from 4,4′‐(2,2,2‐trifluoro‐1‐phenylethylidene]bisphthalic acid anhydride or its diethyl ester and p‐phenylene diamine is described. This material shows unique thermooxidative stability compared with commercially available state‐of‐the‐art polyimides. The optimum monomer stoichiometric ratios of diester to diamine to form a stable 3F‐PDA polyimide were investigated. The studies revealed that diester/diamine ratios greater than 1.000 exhibited the greatest resistance to thermooxidative stability at 371°C in 1 atm of circulating air and at 371°C in 4 atm of flowing air. © 1993 John Wiley & Sons, Inc.
Influence of the structure on thermoset cure kinetics
Authors: Stutz H. , Mertes J.
Published: April 2003

The influence of molecular structure on cure kinetics was studied using a new approach for characterizing the cure kinetics of thermosets in the glass transition region. Reactions in or near the glassy state are controlled by chain mobility, where the whole structural unit undergoes small‐angle oscillation motions around the network link. All structural features affecting the mobility such as stiffness, bulky structures, substitution, symmetry effects, and functionality lead to high segment activation energies and slow final curing. The influence of the segment activation energy on the kinetic curves is also discussed. © 1993 John Wiley & Sons, Inc.
Synthesis, characterization, and kinetic study of compatible SIN's based on diallyl phthalate and epoxy resin
Authors: Lin Mu‐Shih , Yeh Ching‐Chou
Published: April 2003

Diallyl phthalate (DAP) was blended with diglycidyl ether of bisphenol A (DGEBA) in various weight ratios: 100/0, 75/25, 50/50, 25/75, and 0/100. These blends were then cured simultaneously with dicumyl peroxide (DCP) and hexahydrophthalic anhydride (HHPA) in conjunction with 2‐cyanoethyl‐4‐methyl immidazole (EMI‐CN, 0.5% as catalyst) to obtain simultaneous interpenetrating polymer networks (SIN's). H‐bonding between DAP and DGEBA was detected with FTIR. The SIN's thus obtained were characterized with rheometric dynamic spectroscopy (RDS) and differential scanning calorimeter (DSC) to check the compatibility of components. Gel fractions were measured with a Soxhlet extractor. Viscosity increases of all SIN's were measured with a Brookfield viscometer at curing temperatures. Conversions of C  C and epoxide versus cure time were monitored with FTIR and kinetic parameters were calculated and discussed. Experimental results revealed that H‐bonding in the DAP/DGEBA blends was evidenced from the shift of the IR band (vc=o) to a lower wave number, as well as the shift of epoxide band (vδ) to a higher wave number. Complete compatibility between DAP and DGEBA was supported from the single damping peak in DRS and single glass transition in DSC for each of SIN's. Cure dynamic DSC showed shifts of exothermic peaks to higher temperatures for all SIN's. During SIN formation, the slower viscosity increases of SIN's were found, compared with pure DAP and pure DGEBA, indicating retarded cure rates for all SIN's. In addition, lower gel fractions of SIN's were observed, indicating incomplete cure of SIN's. The retarded cure rate was further confirmed by kinetic study. Lower rate constants with higher activation energies for all SIN's were found. An effect of network interlock was proposed to account for these findings. © 1993 John Wiley & Sons, Inc.
Light‐induced polymerization of new highly reactive acrylic monomers
Authors: Moussa K. , Decker C.
Published: April 2003

Acrylic monomers containing an oxetane, dioxolane, oxazolidone or carbonate group in their structural unit have been shown to copolymerize rapidly and extensively with a polyurethane‐diacrylate, upon UV radiation. For the most reactive resin, 50% conversion was reached within 3 ms of exposure to a medium‐pressure mercury lamp. The kinetics of these ultrafast polymerizations was studied quantitatively by infrared spectroscopy. The rate of polymerization, photosensitivity, and amount of residual acrylate in the cured polymer were determined for the various monomers studied, and compared to the values obtained with conventional mono‐, di‐, and triacrylates. The functional group introduced into the monomer unit was shown to have a drastic effect on both the reactivity and the physical characteristics of the photocrosslinked polymer. Soft and highly flexible low‐modulus polymers were produced with the oxetane, dioxolane, and chlorinated monomers, while the carbonate‐acrylate compounds lead to hard and glassy materials. © 1993 John Wiley & Sons, Inc.
Studies on the thermotropic liquid crystalline polycarbonates. II. Synthesis and properties of fully aromatic liquid crystalline polycarbonates
Authors: Sun Shih‐Jieh , Chang Teh‐Chou
Published: April 2003

Four series of fully aromatic polycarbonates were prepared by using melt polycondensation from various novel phenylene diphenyl dicarbonates: 1,4‐phenylenc diphenyl dicarbonate, 1,3‐phenylene diphenyl dicarbonate, methyl‐1,4‐phenylene diphenyl dicarbonate, and chloro‐1,4‐phenylene diphenyl dicarbonate with various diols—4,4′‐biphenyl diol, hydroquinone, 2,7‐naphthalene diol and 1,5‐naphthalene diol, respectively. The thermotropic liquid crystalline properties of synthesized polycarbonates were investigated by: (1) examination of the melt birefringence and stir opalescence by a polarizing microscope equipped with a heating stage, (2) characterization by a differential scanning calorimeter (DSC), and (3) analysis of the wide angle x‐ray diffraction. It was found that the 1,3‐phenylene unit is compensated for the nonlinearity of the carbonate group, and polycarbonates which contain this bent shape unit showed excellent wide mesophase transition in this study. © 1993 John Wiley & Sons, Inc.
Synthesis, characterization and thermooxidative stability of addition polymers from 1,4,5,8‐tetrahydro‐1,4;5,8‐diepoxyanthracene and anthracene end‐capped imide oligomers
Authors: Scola Daniel A.
Published: April 2003

A series of Diels–Alder addition‐type copolymers prepared from 1,4,5,8‐tetrahydro‐1,4;5,8‐diepoxyanthracence and anthracene end‐capped 6F‐PDA imide oligomers were characterized. The composition of the anthracene end‐capped imide oligomers was found to be sensitive to monomer molar ratios and the mode of monomer addition. The resistance of the copolymer to thermooxidative degradation at 316 and 371°C was compared with a similar commercial polymer called Avimid‐N prepared from 4,4′‐hexafluoroisopropylidene‐2,2′ bis(phthalic acid anhydride) and para‐and meta‐phenylene diamine, abbreviated 6F‐PDA. There are strong indications that the copolymers undergo degradation initially by unzipping the diepoxyanthracene unit from the anthracene end‐capped 6F‐PDA oligomer unit (Avimid‐N like repeat unit), followed by a slower degradation of the more stable residual 6F‐PDA unit. © 1993 John Wiley & Sons, Inc.
Radical alternating copolymerization of vinyl ethers
Authors: Kharas G. B. , Ajbani H.
Published: April 2003

New alternating equimolar copolymers of electrophilic trisubstituted ethylenes, methyl 3‐phenyl‐2‐cyanopropenoate and 2‐phenyl‐1,1‐dicyanoethene, with ethyl, n‐butyl, i‐butyl, t‐butyl, 2‐chloroethyl, and phenyl vinyl ethers were prepared by free radical initiation. Chemical compositions of the copolymers are 1 : 1 in broad ranges of monomer ratios. The copolymerization rate of both electrophilic monomers with the vinyl ethers increase in the series 2‐chloroethyl > ethyl > phenyl > n‐butyl > i‐butyl > t‐butyl. These variations in the reactivity of the vinyl ethers are discussed in terms of their preferred conformations in donor‐acceptor complexes with electrophilic trisubstituted ethylenes. © 1993 John Wiley & Sons, Inc.
Polyesters, polyurethanes and epoxy resins derived from 2,2′‐(1,4‐phenylenedivinylene)bis‐8‐hydroxyquinaldine and 6‐(4‐hydroxystyryl)‐3‐hydroxypyridine
Authors: Diakoumakos Constantinos D. , Mikroyannidis John A.
Published: April 2003

New polyesters and polyurethanes as well as diepoxides bearing styrylpyridine segments were prepared utilizing 2,2′‐(1,4‐phenylenedivinylene)bis‐8‐hydroxyquinaldine (PBHQ) and 6‐(4‐hydroxystyryl)‐3‐hydroxypyridine (HSHP) as starting materials. The polyesters were prepared by reacting PBHQ or HSHP with terephthaloyl dichloride in the presence of an acid acceptor utilizing the solution polycondensation method. The polyurethanes were prepared from the reactions of PBHQ and HSHP with tolylene diisocyanate and methylenebis(4‐phenylisocyanate). In addition, model diesters and diurethanes were synthesized by reacting PBHQ and HSHP with benzoyl chloride and phenyl isocyanate, respectively. Model compounds and polymers were characterized by FT‐IR and 1H‐NMR spectroscopy as well as by DTA and TGA. Diepoxides were also prepared from the reactions of PBHQ and HSHP with epichlorohydrin which were polymerized in the presence of 4,4′‐diaminodiphenylsulfone. The polyesters were the most thermostable polymers obtained. After curing at 240°C for 20 h, they were stable in N2 up to 345–370°C and afforded anaerobic char yields of 65–75% at 800°C. © 1993 John Wiley & Sons, Inc.
Exchange reactions occurring through active chain ends: Melt mixing of nylon 6 and polycarbonate
Authors: Montaudo Giorgio , Puglisi Concetto , Samperi Filippo
Published: April 2003

The chemical reactions occurring in the melt mixing of nylon6/polycarbonate (Ny6/PC) at 240°C were investigated. The reaction of equimolar Ny6/PC blends can be reconciled within the overall scheme of an exchange reaction occurring with the attack of active amino terminals on the inner carbonate groups. We have performed the synthesis of low molecular weight amino‐terminated nylon 6 and the effect of the active amino terminal groups on the exchange kinetics was investigated. The exchange reaction yields sizeable amounts of copolymer, in fact after 75 min of melt mixing the (initially equimolar) blend contains 30 mol of unreacted PC and 70 mol of Ny6/PC copolymer (all the Ny6 was therefore incorporated in the copolymer). Trifluoroacetylation of nylon 6 was used to produce CHCl3‐soluble Ny6/PC copolymers, that could be analyzed by NMR. The NMR analysis yielded, beside the copolymer composition, evidence of the presence of urethane units interconnecting the Ny6 and PC blocks. The amount of urethane units increased with the reaction time, indicating a reduction of the block size as a function of the extent of exchange. Our study established the structure of the products formed, provided the materials balance of the process, and investigated some salient kinetic aspects. A thermal degradation study was also performed by thermogravimetry and direct pyrolysis mass spectrometry, to identify the products formed in the thermal treatment of the blends and to investigate the possible role of the inner amide groups in the intermolecular exchange reactions occurring between Ny6 and PC. Our results prove that these reactions occur above 300°C, and that only the cleavage of carbonate groups, by means of Ny6 amino end groups, is actually occurring at 240°C. © 1994 John Wiley & Sons, Inc.
Preparation and characterization of acrylates and polyacrylates having variable fluorine contents and distributions
Authors: Guo X. Andrew , Hunter Allen D. , Chen Jie
Published: April 2003

Five acrylic esters having different fluorine contents and distributions in their side‐groups (i.e., CH2=CHC(O)OR, where R = C(CH3)2C6F4H, C(CH3)2C6F5, C(CF3)2C6F5, C(CF3)2C6H5, and C(CH3)2C6H5) have been prepared from the reactions of the lithium salts of their corresponding alcohols with acryloyl chloride. These monomers are polymerized under identical conditions by the radical initiator AIBN and five polyacrylates were prepared having the structure of  [ CH2CHC(O)OR]n. These addition polymers were compared and fully characterized by GPC, VPO, DSC, TGA, NMR, IR, and UV‐visible spectroscopies, and they showed potential for practical applications. Significant differences in their thermal stabilities were found with respect to fluorine contents and distributions in these polyacrylates, and the highest stability arises from CF3 substitutions in the side‐chains of the polymers. © 1994 John Wiley & Sons, Inc.
Preparation and characterization of fluorine‐containing aromatic condensation polymers. II. Preparation and characterization of fluorine‐containing aromatic polyformal and copolyformals by solution polycondensation of 2,2‐bis (4‐hydroxyphenyl)‐1,1,1,3,3,3‐hexafluoropropane and/or 2,2‐bis‐(4‐hydroxyphenyl)propane with dichloromethane
Authors: Saegusa Yasuo , Kuriki Minoru , Kawai Akihiro , Nakamura Shigeo
Published: April 2003

A series of fluorine‐containing aromatic homopolyformal and copolyformals with a wide range of unit ratio were synthesized by the solution polycondensation of 2,2‐bis (4‐hydroxyphenyl)‐1,1,1,3,3,3‐hexafluoropropane (Bisphenol AF) and/or 2,2‐bis (4‐hydroxyphenyl)propane (Bisphenol A) with dichloromethane, and the effect of the fluorine substitution on the preparation and properties of these polymers was investigated by comparing with those of Bisphenol‐A‐based homopolyformal without fluorine. Irrespective of the ratio of Bisphenol AF, high‐molecular‐weight, fluorine‐containing polyformals with reduced viscosities of 1.4–5.3 dL/g were obtained in high yields by using dichloromethane as both comonomer and solvent, potassium hydroxide as a base, and N‐methyl‐2‐pyrrolidone as a comedium at 75°C for 4 h. Their solubility increased markedly by the introduction of fluorine atom. Colorless, transparent, and tough films were cast from chloroform solution irrespective of fluorine content. These films had good mechanical properties comparable to that of Bisphenol‐A‐based homopolyformal. The contact angles by water were larger than 90°, regardless of their fluorine contents, at 25°C. The glass transition temperature and thermal stability increased monotonically with increasing fluorine content. © 1994 John Wiley & Sons, Inc.
High modulus polyimide/polyimide molecular composite films that utilize acetylene unit as a crosslink site
Authors: Takeichi Tsutomu , Takahashi Nobuyuki , Yokota Rikio
Published: April 2003

Polyimide/polyimide molecular composite (MC) films comprised of a rigid polyimide derived from biphenyltetracarboxylic dianhydride (BPDA) and p‐phenylenediamine (PDA) and a flexible polyimide derived from BPDA and bis (3,3'‐diaminodiphenyl) acetylene (intA) and/or oxydianiline (ODA) were prepared by blending the polyamic acid solutions in 7 : 3 weight ratio, and then imidizing the blend films. Acetylene content in the flexible polyimide backbone was controlled by the ratio of intA and ODA. Cold‐drawing of the blend polyamic acid films, followed by imidization, gives high modulus polyimide/polyimide MC films. The modulus of the MC films increased almost linearly with the draw ratio, reaching 25.5 GPa for the 40% drawn film. Acetylene groups in the flexible polyimide can be thermally cured to crosslink. The onset of exotherm appeared at 340°C on DSC, reaching maximum at 398°C. After the thermal crosslinking, the MC films maintained the high modulus, though elongation became small. Taking advantage of the crosslinkable acetylene units, two MC films were laminated and processed at 400°C for 20 min under 100 kg/cm2 to give a good‐quality laminate film. The interface of the two films was strongly bonded through the crosslinking of acetylene groups. Laminate films maintained the high modulus afforded by the cold‐drawing. © 1994 John Wiley & Sons, Inc.
A study on the mechanism of dissolution of the cellulose/NH3/NH4SCN system. I
Authors: Cuculo J. A. , Smith C. B. , Sangwatanaroj U. , Stejskal E. O. , Sankar S. S.
Published: April 2003

Ammonia/ammonium thiocyanate (NH3/NH4SCN) is an excellent swelling agent and solvent for cellulose, even at a high degree of polymerization. Because polymorphic conversion in cellulose has been a long‐standing, perplexing, troublesome problem, we have undertaken to study that mechanism. Solid state CP/MAS 13C‐NMR and X‐ray analysis proved to be very useful analytical techniques for the task. It appears that during temperature cycling, specific cellulosic inter‐ and intramolecular hydrogen‐bonds are broken as polymorphic conversion proceeds sequentially from the polymorph I to III, and finally at total solvation to amorphous. This proceeds correspondingly via transformation of the polymorph conformations of CH2OH from trans‐gauche, “tg,” to gauche‐trans, “gt,” to gauche‐gauche, “gg.” © 1994 John Wiley & Sons, Inc.
A study on the mechanism of dissolution of the cellulose/NH3/NH4SCN system. II.
Authors: Cuculo J. A. , Smith C. B. , Sangwatanaroj U. , Stejskal E. O. , Sankar S. S.
Published: April 2003

In a previous article,1 we reported on the interaction of cellulose with NH3/NH4SCN by using solid state CP / MAS 13C‐NMR, wide‐angle X‐ray and other techniques. It appears that during an imposed temperature cycling sequence, specific cellulosic inter‐ and intramolecular hydrogen bonds are broken as polymorphic conversion and, ultimately, dissolution occurs. Cellulose is converted from the polymorph I to II to III and, finally, to amorphous. We speculate that these changes proceed via transformation of the polymorph conformations of CH2OH from trans‐gauche, “tg,” to gauche‐trans, “gt,” to gauche‐gauche, “gg.” Remarkably, the temperature cycling effectively and rapidly effects these changes, seemingly, by invoking at two different temperatures (22°C and −78°C), a subtle but powerful temperature‐related interplay of enthalpic and entropic forces. At the higher of the cycling temperature limits, entropy and van der Waals forces dominate, causing NH3 to partition in favor of the liquid phase. At the lower of the temperature cycling limits, enthalpy dominates and the situation is reversed favoring NH3 partition toward the cellulose, resulting in breakage of inter‐ and intracellulosic H‐bonds by the interpenetrating ammonia to form new H‐bonds between cellulose and ammonia, leading ultimately to conformational changes and, ultimately, even dissolution. © 1994 John Wiley & Sons, Inc.
Stability of chemical sequence in a periodic polymeric nematogen
Authors: Wu J. L. , Stupp S. I.
Published: April 2003

The stability of a polymeric nematogen's chemical sequence was studied by differential scanning calorimetry, optical microscopy, and 13C‐NMR; the nematogen studied was a thermotropic polyester and had a periodic chemical structure. Model compounds were used to investigate transesterfication in the melt at different temperatures with the addition of phenol or benzoic acid as analogues of polymer end groups. Ester interchange reactions at high temperature were found to be partly suppressed when acidic end groups of the periodic nematogen were capped. However, sequence reorganization was completely suppressed in capped nematogens when temperatures remained below the isotropization transition of the nematogen investigated. Rapid disordering of the periodic nematogen was observed above the nematic‐isotropic transition, suggesting that both chemical and physical factors play a role in sequence redistribution of periodic nematogens. © 1994 John Wiley & Sons, Inc.
Template polymerization of multiacrylate
Authors: Jantas R. , Szumilewicz J. , Strobin G. , Połowiński S.
Published: April 2003

By reacting poly (2‐hydroxyethyl methacrylate) with acryloyl chloride, multiacrylate connected through a covalent bond with polymethacrylate chain (template) has been obtained. The free‐radical polymerization of multiacrylate in dilute dioxane solutions at 75°C and 85°C was examined by IR spectrophotometry and the distribution of molecular weights of the resultant products was evaluated by gel permeation chromatography. The findings show that under selected conditions the polymerization proceeds along ordered acrylic double bonds on the template and results in a ladder‐type polymer. At a temperature of 85°C, in addition to the intramolecular cyclopolymerization, intermolecular reactions proceed to a minor extent. © 1994 John Wiley & Sons, Inc.