bluuebunny/crossref_metadata_2025 huggingface dataset:
Liquid–crystalline copoly(ester–amide)s prepared from hydroxybenzoic and 4‐aminobenzoic acids
Authors: Chen Wen‐Hsin , Chang Teh‐Chou , Higashi Fukuji
Published: April 2003

Copolycondensations of 3,5‐dimethoxy‐4‐hydroxybenzoic (syringic acid, SGA), 4‐hydroxybenzoic(PHB), and 4‐aminobenzoic (PAB) acids with diphenyl chlorophosphate(DPCP)/LiCl/pyridine were studied. Random copolycondensations of a wide range of monomer compositions afforded copolymers exhibiting birefringence at room temperature. However, when the sequence of PHB and PAB was fixed by using a newly prepared monomer, 4‐(4′‐aminobenzoyloxy) benzoic acid (PABBA), the ordered copolymers thus prepared showed birefringence above 200°C, but not at room temperature. Variations in solubility and thermal behavior were also observed in randomly and sequentially prepared copolymers. The monomer sequences in copolymers in random copolycondensations could be changed by controlling the reaction of monomers with DPCP.
Oxidation of polyethylene surface by corona discharge and the subsequent graft polymerization
Authors: Iwata Hiroo , Kishida Akio , Suzuki Masakazu , Hata Yoshio , Ikada Yoshito
Published: April 2003

Oxidation of a polyethylene (PE) surface by corona discharge and the subsequent graft polymerization of acrylamide (AAm) were studied. The maximum amount of peroxides introduced by corona treatment at a voltage of 15 kV was about 2.3 × 10−9 mol cm−2. The decomposition rate of peroxide and the dependence of graft amount on the storage period of the corona‐treated PE films showed that there were several kinds of peroxides, the labile one being mainly responsible for the initiation of graft polymerization. When the corona‐treated film was brought into contact with a deaerated aqueous solution of AAm, graft polymerization took place more strongly with the treatment time, but was reduced after passing a maximum. Although the x‐ray photoelectron spectroscopic analyses of the corona‐treated PE films showed homogeneous oxidation of the outer polymer surface by corona discharge, optical microscopy on the cross section of the grafted film revealed the graft polymerization to be limited to a very thin surface region.
Polymer drying, 1. Time‐studies of desorption from liquid saturated poly(styrene‐co‐divinylbenzene) microparticles
Authors: Errede L. A. , Kueker M. J. , Tiers G. V. D. , Van Bogart J. W. C.
Published: April 2003

Time studies of evaporation from liquid‐saturated poly[(Sty)98‐co‐(DVB)2] particles enmeshed in poly(tetrafluoroethylene) microfibers show that it is possible to distinguish kinetically between volatile sorbed molecules not absorbed to the polymer chain and those that are adsorbed to it. Elimination of the nonadsorbed molecules occurs first, and it follows zero‐order kinetics. The subsequent elimination of the residual volatiles, namely the adsorbed molecules, follows first‐order kinetics, with a rate constant that remains constant only until the enmeshed microparticles undergo transition from the gel to the glass state. Thereafter, is observed a sequence of up to six independent rate constants in a series of intervals, the durations of which increase exponentially. This is interpreted to mean that after evaporation to the glass transition composition, the total weight of residual adsorbed molecules is given by a linear combination of exponential decay functions for up to six populations of adsorption sites, the rate constants for which reflect the force of association between the sites and the retained molecules.
Binding methyl orange and hydrophobic fluorescent probes by poly(2‐dimethylaminoethyl methacrylate) and copolymers of 2‐dimethylaminoethyl methacrylate and N‐vinyl‐2‐pyrrolidone: pH dependence of the binding and fluorescence intensity
Authors: Takagishi Toru , Hosokawa Toshitsugu , Hatanaka Yasumichi
Published: April 2003

The pH dependence of the interaction of poly(2‐dimethylaminoethyl methacrylate) and copolymers of 2‐dimethylaminoethyl methacrylate and N‐vinyl‐2‐pyrrolidone with methyl orange, 2‐p‐toluidinylnaphthalene‐6‐sulfonate (TNS), and 1,6‐diphenyl‐1,3,5‐hexatriene (DHT) was studied by equilibrium dialysis and fluorescence measurements at pH's 7–10. The first binding constant accompanying the binding of methyl orange and TNS by the polymers, in particular the homopolymer, shows a maximum around pH 8 and maximal fluorescence intensity of TNS is obtained around pH 8.5 in the presence of the polymers. To elucidate these observations the pH‐induced conformational changes of the homopolymer were examined by potentiometric titration and viscosity measurements and the thermodynamic parameters that accompany the binding were calculated. The polymer was found to change from an extended coil at lower pH to a compact coil at higher pH. The electrostatic attraction between the sulfonate group of the small molecule and the protonated nitrogen atoms on the polymer is increased at lower pH and the hydrophobic interaction between the hydrophobic moieties of the polymer and the small molecule is enhanced at higher pH. The results obtained for the dye binding and fluorescence intensity were discussed in terms of the electrostatic and hydrophobic interactions.
Studies on polymerization of vinyl acetate using ylide as an initiator and degradative transfer agent
Authors: Shukla A. K. , Saini S. , Kumar P. , Rai J. S. P. , Srivastava A. K.
Published: April 2003

The polymerization of vinyl acetate initiated by β‐picolinium‐p‐chlorophenacylide was carried out at 30, 35, and 40°C, using the conventional dilatometric technique. The initiator and the monomer exponent values were 0.80 ± 0.15 and unity, respectively. The polymerization was inhibited in the presence of hydroquinone, but was favored by nonpolar solvent and polymerization temperature. The energy of activation was 90.3 kJ mol−1. An average value of k/kt for the present system was found to be 0.37 × 10−2 L mol−1 s−1. The results are explained in terms of radical mode of polymerization with degradative initiator transfer; the principal mode of termination, however, was biomolecular.
Copolymerization of isobutylene with 1,4‐13C‐isoprene
Authors: Kuntz Irving , Rose Kenneth D.
Published: April 2003

Copolymers of isobutylene with 1,4‐13C‐isoprene have been prepared in methyl chloride solvent at −90 to −50°C using aluminum chloride and organoaluminum halide initiators. The examination of these copolymers containing 0.5 to 3.0 mol % of the diolefin by 13C‐NMR has given new information about the mechanism of the copolymerization. It appears that every macromolecule ends in an isoprene derived unit; that chain transfer to monomer by an isoprene‐derived propagating carbocation is the dominant chain breaking process. The copolymer triad sequences have been unambiguously assigned and analyzed in both batch and continuous stirred tank reactor copolymers. The relative concentrations of the triads agree with those predicted by published reactivity ratios.
Modification of polymers via electrophilic aromatic substitution
Authors: Mallakpour Shadpour E. , Butler George B.
Published: April 2003

Three vinyl monomers, 2,4,6‐trimethoxystyrene, 4‐(N,N‐dimethylamino)styrene, and N‐methyl‐2‐vinylpyrrole, were synthesized via the Wittig reaction from the corresponding aldehyes. These monomers were homopolymerized by radical polymerization using α,α′‐azoisobutyronitrile (AIBN) as initiator at 60°C. The reaction of these polymers with 4‐phenyl‐1,2,4‐triazoline‐3,5‐dione (phTD) and 4‐methyl‐1,2,4‐triazoline‐3,5‐dione (MeTD) was investigated. Although polytrimethoxystyrene reacts slowly with PhTD at room temperature, the other two polymers react fast and lead to the incorporation of the triazolinedione unit into the side chain of the polymer via electrophilic aromatic substitution. The reaction of bistriazolinediones (BTD) with these polymers was performed in dimethylformamide using 10–20% molar concentration of the BTD. The resulting crosslinked polymers are insoluble in polar as well as nonpolar solvents. Some physical properties of the unmodified and modified polymers were studied.
Copolymerization and interaction of acrylonitrile and indene
Authors: Mikhael M. G. , Mokhtar S. M. , Saad G. R. , Naoum M. M. , Elsabee M. Z.
Published: April 2003

The donor–acceptor interaction of acrylonitrile (AN) with indene (In) has been investigated by means of ultraviolet spectroscopy and dielectric polarization measurements. The latter method yielded a value of 0.5 for the association constant of the charge‐transfer‐complex (CTC) and a 4.02 D for its dipole moment. The copolymerization of the two monomers was characterized by a tendency towards alternation when conducted in the bulk. This might be due to the participation of a weak CTC in the process of copolymerization. However, this tendency disappeared in polar solvents such as DMF.
The solid state photobleaching and photocrosslinking of copolymers containing the anthracene chromophore
Authors: Hargreaves John S.
Published: April 2003

Copolymers of methyl methacrylate with an anthracene derivative are photodegraded in the solid state to give crosslinked material. The mechanism of insolubilization is dependent on the nature of the substituents at both the 9 and 10 positions of the anthracene chromophore. Photodimerization is the primary and most efficient cause of insolubilization if one of these positions is unsubstituted. Photodimerization does not occur if both of these positions are substituted; instead crosslinking is caused by photolysis of the endoperoxide of the parent anthracene. Bromination can sensitize the initial photooxidation and subsequent crosslinking in a copolymer where photodimerization does not occur. As a consequence of the crosslinking the rate of photobleaching of the anthracene chromophore by 1ΔgO2 is severly curtailed. Poly(methyl methacrylate), a positive‐tone polymer when exposed to UV light, is made negative acting by the incorporation of bound anthracene chromophores.
Thermally stable polymers based on bismaleimides containing amide, imide, and ester linkages
Authors: Melissaris Anastasios P. , Mikroyannidis John A.
Published: April 2003

Seven new structurally different bismaleimides were synthesized and characterized by infrared and proton nuclear magnetic resonance spectroscopy. The chain of these polymer precursors was extended by incorporating amidized, imidized, and esterified 4‐chloroformyl phthalic anhydride. The bismaleimides containing amide and imide linkages were prepared by a simple synthetic route based on the reaction of the monomaleamic acid derived from various aromatic diamines (1 mol) with 4‐chloroformyl phthalic anhydride (0.5 mol) and subsequent cyclodehydration of the intermediate triamic acid. In addition, chain extended bismaleimides were prepared by reacting the monomaleamic acid derived from p‐phenylenediamine with several dianhydrides such as p‐phenylene bis(trimellitamide anhydride), p‐phenylene bis(trimellitate anhydride), and bis‐phenol A bis(trimellitate anhydride). The differential thermal analysis scans of bismaleimides showed exotherms at 221–304°C associated with their polymerization reactions. The thermogravimetric analysis traces of polymers did not show a weight loss up to 351–393 and 344–372°C in N2 and air atmospheres, respectively. The anaerobic char yield of polymers at 800°C was 44–61%. These polymers can be used for fabrication of composites having improved properties.
Copolymerization of 2‐methylene‐4‐phenyl‐1,3‐dioxolane with electrophilic vinyl monomers through zwitterionic mechanism
Authors: Yokozawa Tsutomu , Takagi Jun , Endo Takeshi
Published: April 2003

Spontaneous copolymerization of cyclic ketene acetal, 2‐methylene‐4‐phenyl‐1,3‐dioxolane (I) with common electrophilic vinyl monomers, such as methyl α‐cyanoacrylate (MCA), acrylonitrile (AN), and methyl methacrylate (MMA) were investigated to further explore zwitterion polymerization method with cyclic ketene acetals. In the reaction of I with MCA and AN, spontaneous copolymerization took place at ambient temperature. The copolymers of I with MCA gave low molecular weight polymers, but copolymers obtained with I and AN were high molecular weight polymers. In the reaction of I and MMA, high molecular weight copolymer was obtained only at temperatures above 80°C. Thus, obtained polymers were not the alternating copolymers and possessed high I content in all the cases. From the above results, macrozwitterionic mechanism was suggested as discussed.
Aspects of degradation and stability of ABS copolymers. I. Effect of β‐carotene as antioxidant
Authors: Abdel‐Razik E. A.
Published: April 2003

The oxidative degradation of polybutadiene–styrene–acrylonitrile (ABS) copolymer was extensively investigated. Three factors were studied: the influence of ageing temperature on the rate of the oxidation of the copolymer; the efficiency of β‐carotene as chain breaking antioxidant; and the effect of butadiene content on the rate of the oxidative degradation of the ABS copolymer.
Copolymerization of styrene with maleic anhydride initiated by thiol compounds
Authors: Kuramoto Noriyuki , Iwaki Takeshi , Satoh Akihiro , Nagai Katsutoshi
Published: April 2003

Copolymerization of styrene (ST) with maleic anhydride (MAH) initiated by thiol compound was investigated under various conditions. The kinetics of copolymerization of ST with MAH initiated by p‐toluenethiol (pTT) was studied in dioxane in the temperature range of 25–60°C, and the rates (Rp) of copolymerization and activation energy were determined. Rp was found to depend on [pTT],0.6 ([ST] + [MAH])2.7. The overall energy of activation was 10.8 kcal/mol in the temperature range of 25–60°C. A mechanism involving the formation of a complex between MAH and pTT the decomposition of which yields the initial radical is suggested.
New polymer syntheses 22. LC‐poly(esterimide)s derived from trimellitic acid, ω‐amino acids and hydroquinone or 4,4′‐dihydroxybiphenyl
Authors: Kricheldorf Hans R. , Pakull Ralf , Buchner Stefan
Published: April 2003

Diacids with variable spacer length were prepared by condensation of trimellitic anhydride and ω‐amino acids. From these diacids, homopolyesters were prepared by thermal condensation with the acetates of hydroquinone or 4,4′‐dihydroxy biphenyl and a series of copolyesters containing 4‐hydroxy benzoic acid. The same LC poly(ester imide)s could also be prepared in a “one‐pot procedure” from trimellitic anhydrid, lactams, and bisphenol acetates. The differential scanning calorimetry (DSC) traces of most poly(ester imide)s exhibit two endotherms representing the solid → LC phase transition (Tm1) and the LC phase → isotropic melt transition (Tm2). Observation under the polarizing microscope and wide‐angle X‐ray scattering (WAXS) measurements suggest that the LC phase formed immediately above the melting points (Tm1) have a smectic character. Poly(ester imide)s of 4,4′‐dihydroxybiphenyl possess higher melting points and a broader temperature range of the LC phase than those of hydroquinone. The copolyesters possess a nematic melt over a broad temperature range. Thermomechanical analyses under low pressure (0.05 kg/mm2) gave heat distortion temperatures close to the melting points (Tm1), and under high pressure (1 kg/mm2), values between Tm1 and the glass transition temperatures (Tg). Thermogravimetric measurements indicate that processing from the melt is feasible up to temperatures around 340°C.
Synthesis and polymerization of multiallyl monomer in matrix of poly(methacryloyl chloride)
Authors: Jantas R. , Połowiǹski S. , Podešva J.
Published: April 2003

By reacting poly(methacryloyl chloride) (PMKC) with allyl amine, a multiallyl monomer in PMKC matrix has been obtained. Free‐radical polymerization of multiallyl monomer in diluted solutions at a concentration of 12 g/L multiallyl monomer occurs partly along ordered allyl units in the matrix and results in ladder‐type branched polymers. The polymers obtained are soluble in alcohols, DMF, DMSO and have unreacted allyl double bonds. The structures of multiallyl monomer and homopolymer have been found on the basis of elemental analysis, IR and 1H‐NMR spectra and an examination of the products of hydrolysis. The effect of the reaction of degradative chain transfer on the structure of the polymer obtained has been discussed.
Electropolymerization of benzene and biphenyl in organic media: Influence of different parameters (solvent, water, acidity, salt) on the formation of polyparaphenylene films (PPP)
Authors: Aeiyach S. , Lacaze P. C.
Published: April 2003

The electrosynthesis of polyparaphenylene films (PPP) by oxidation of benzene or biphenyl on a Pt electrode was studied in different organic media. Film formation was possible only if the solvent had acidic properties according to the Lewis concept, and if the water content of this medium was less than 5 × 10−2M. Addition of an excess of P2O5 or CuCl2 into the medium increased the acidity and improved the adherence and the homogeneity of the films considerably. PPP films were electroactive and conductive if the electrolysis was carried out in the presence of salts containing BF, SbF, PF anions; they were insulating with perchlorate salts. IR analysis of these polymers showed highly crosslinked structures and the chains were constituted of about 10 para coupled phenyl moieties.
13C‐NMR study of arylene–ether–ketone copolymers
Authors: Havens John R. , Reimer Karen B.
Published: April 2003

The chemical microstructure of arylene–ether–ketone copolymers of terephthaloyl chloride (TCl), 1,4‐diphenoxybenzene (DPB), and diphenyl ether (DPE) has been characterized by 13C‐NMR. Copolymers synthesized via two Friedel–Crafts reaction have been investigated; the first reaction uses HF and BF3 to catalyze polymerization, and the second uses LiCl to moderate the activity of the Lewis‐acid catalyst, AlCl3. The HF/BF3 approach results in random copolymers, in which the TCI displays no preference in reacting with either DPB or DPE. The buffered AlCl3 approach yields somewhat blocky copolymers, in which the DPB and DPE tend to segregate. The degree of segregation in these materials has been quantified by formulas for the number‐average block lengths.
Polyamides containing arylene sulfone ether linkages
Authors: Idage S. B. , Idage B. B. , Shinde B. M. , Vernekar S. P.
Published: April 2003

Polyamides containing arylene sulfone ether linkages were synthesized from 4,4′‐[sulfonylbis(p‐phenyleneoxy)] dibenzoyl chloride (SPCI), 3,3′‐[sulfonylbis(p‐phenyleneoxy)] dibenzoyl chloride (SMCl), and arylene sulfone ether diamines (SED), by solution and interfacial polymerization techniques. In solution polymerization, the effect of various acid acceptors such as propylene oxide (PO), lithium chloride (LiCl)/lithium hydroxide (LiOH), and triethylamine (TEA) on molecular weight of the polyamides was studied. The effect of methyl substituted and unsubstituted aromatic sulfone ether diamines on molecular weight and thermal properties of polyamides was also studied. The polyamides prepared were characterized by solution viscosity, elemental analysis, thermal gravimetric analysis, differential scanning calorimetry, and x‐ray diffraction. Physical and thermal properties of polyamides prepared from SPCl and SED were compared with the polyamides prepared from SMCl and SED.
A study of the graft copolymerization of methacrylic acid onto starch using the H2O2/Fe++ redox system
Authors: Vázquez B. , Goñi I. , Gurruchaga M. , Valero M. , Guzmán G. M.
Published: April 2003

Graft copolymerization of methacrylic acid (MetAc) onto potato starch using H2O2/Fe++ redox system was investigated. The best conditions of the grafting reaction were determined and several variables were studied: initiator and monomer concentrations, time, and temperature. Percent grafting efficiency, percent grafting, percent grafted monomer conversion, and total conversion were obtained. The optimum graft yield was obtained at 7.3 × 10−3M H2O2 concentration and it was favored by increasing the methacrylic acid concentration and reaction time.
Co‐oligomerization of ethylene and higher linear alpha olefins. I. Co‐oligomerization with the sulfonated nickel ylide‐based catalytic system
Authors: Kissin Y. V.
Published: April 2003

Co‐oligomers of ethylene and a series of linear α‐olefins (propylene, 1‐butene, 1‐hexene, 1‐heptene, 1‐octene, and 1‐decene) were synthesized with a homogeneous catalyst consisting of sulfonated nickel ylide and diethylaluminum ethoxide at 90°C. GC analysis of the co‐oligomerization products allowed complete structural identification of all reaction products, α‐olefins with linear and branched chains, vinylidene olefins, and linear olefins with internal double bonds. The article describes the reaction scheme of ethylene–olefin co‐oligomerization. The scheme includes chain initiation reactions (insertion of ethylene or an olefin into the NiH bond), chain propagation reactions, and chain termination reactions via β‐hydride elimination. Primary and secondary inertions of α‐olefins into the NiH bond in the initiation stage proceed with nearly equal probabilities. Higher olefins participate in the chain growth reactions (insertion into the NiC bond) also both in primary and secondary insertion modes. The primary insertion of an α‐olefin molecule into the NiC bond produces the β‐branched NiCH2CR1R2 group. This group is susceptible to β‐hydride elimination with the formation of vinylidene olefins. However, the NiCH2CR1R2 groups can participate in further ethylene insertion reactions and thus form vinyl oligomerization products with branched alkyl groups. On the other hand, the secondary insertion of an α‐olefin molecule into the NiC bond produces the α‐branched NiCR1R2 bond which does not participate in further chain growth reactions and undergoes the β‐hydride elimination reaction with the formation of linear reaction products with internal double bonds. Most co‐oligomer molecules contain only one α‐olefin fragment. However, the analysis of ethylene‐propylene and ethylene‐1‐heptene co‐oligomers allowed identification of products with two olefinic fragments which are also formed in the copolymerization reactions with small yields.
Synthesis and thermal self‐crosslinking reaction of polymer containing spiro ortho ester and carboxylic acid
Authors: Isobe Naoki , Numasawa Hideki , Nishikubo Tadatomi , Togoshi Hirotaka , Endo Takeshi
Published: April 2003

Polymers with both pendant spiro ortho ester and carboxylic acid moieties were synthesized by partial esterification of poly(methacrylic acid), poly(methacrylic acid‐co‐methyl methacrylate), or poly(methacrylic acid‐co‐styrene) with halomethylated spiro ortho esters in the presence of 1,8‐diazabicyclo[5,4,0]undecene‐7 in dimethyl sulfoxide. The extent of esterification increased with increasing reaction temperature. The reaction of polymeric carboxylic acids with chloromethylated spiro ortho esters proceeded to 80% of conversion at 100°C for 120 h. In contrast, the degree of esterification with bromomethylated spiro ortho ester reached 80% at 60°C within 24 h. Thermo‐crosslinking of polymers having pendant spiro ortho ester moiety and carboxylic acid could be effected in films. The rate of spiro ortho ester ring‐opening increased with increasing reaction temperature and with increasing content of carboxylic acid groups in the polymer. Further, the rates of gel production were also measured. The polymer containing an equimolar mixture of spiro ortho ester moieties and carboxylic acids exhibited the highest reactivity. In addition, it was found that thermal crosslinking reaction of the polymer occurred with minimum volume shrinkage.
Microstructure of poly(alkylene phosphates) related to biopolymers (teichoic acids)
Authors: Biela Tadeusz , Kłosiński Paweł , Penczek Stanisław
Published: April 2003

The microstructure of polyphosphites and polyphosphates obtained by the ring‐opening polymerization of asymmetrically substituted 5‐membered cyclic phosphites was studied. It has been established, using 31P NMR, that 4‐substituted 2‐hydro‐2‐oxo‐1,3,2‐dioxaphospholanes underwent polymerization giving polymers with head‐to‐tail dyads as well as head‐to‐head and tail‐to‐tail structures. Analyses of 31P NMR spectra of racemic and optically active poly(2‐hydro‐4‐methyl‐2‐oxo‐1,3,2‐dioxaphospholane) and model compounds estimated the statistical mode of ring scission of cyclic phosphites. Similar results were obtained for the polymerization of 4‐acetoxymethyl‐2‐hydro‐2‐oxo‐1,3,2‐dioxaphospholane, which provided the simplest model of teichoic acid, namely poly(1,2‐glycerol phosphate).
The polymerization of isobutylene by AlCl3 in CH2Cl2 and the role of CH2Cl2 in the initiation reaction
Authors: Toman L. , Spěváček J. , Pokorný S.
Published: April 2003

A solution of AlCl3 in CH2Cl2 prepared in advance was used 18 days after the mixing of the components as an initiation system in the polymerization of isobutylene performed in CH2Cl2 in the temperature range between −10 and −20°C. The 1H‐NMR analysis of polyisobutylene (PIB) samples synthesized to low and high conversion showed that it is the initiation reaction and not the transfer reaction to dichloromethane that is responsible for the CH2Cl endgroup in the polymer chain. In case of the transfer to monomer formation of PIB with internal terminal unsaturation [PIBCHC(CH3)2] is preferred to external unsaturation [PIBCH2(CH3)CCH2]. The solutions of AlCl3 in CH2Cl2 showed an absorption band at λmax = 302 nm.
New elastomeric networks based on functionalized ethylene–propylene rubbers and hydroxyl terminated polybutadiene. I. A kinetic study on the monoesterification
Authors: Immirzi Barbara , Laurienzo Paola , Malinconico Mario , Martuscelli Ezio
Published: April 2003

Ethylene–propylene random copolymers bearing grafted succinic anhydride functions have been reacted with an α,ω‐hydroxyl telechelic polybutadiene to obtain elastomeric interpolymer complexes. A kinetic study has been carried out by infrared techniques to study the influence of the addition of catalyst, stoichiometry, and temperature on the degree of monoesterification reaction.
The electrocopolymerization of styrene with vinyl acetate in an organic solvent
Authors: Calafate Bettina A. L. , Garcia Maria Elizabeth F. , Mano Eloisa B.
Published: April 2003

Copolymers of styrene and vinyl acetate were synthesized electrochemically. The reaction system was composed of methylene chloride as the solvent, and a quaternary ammonium salt as the electrolyte. The reactions were run in a divided cell and the influence of current strength, reaction time, and temperature on the yield, molecular weight, and chemical composition of the resulting copolymers was investigated. It was found that the polymer chains were composed mainly of styrene units.
Quinone–amine polymers. II. 1,3‐bis(3‐aminophenoxy) benzene‐p‐benzoquinone oligomers
Authors: Kaleem K. , Chertok F. , Erhan S.
Published: April 2003

A novel oligomeric compound has been synthesized by reacting 1,3 bis‐(3‐aminophenoxy)‐benzene (APB) with p‐benzoquinone. A dark reddish brown product has been characterized using UV, IR, and NMR spectra, and elemental analysis. It, too, adheres to metals, as does another polyetheramine‐p‐benzoquinone polymer synthesized in Part I [Prog. Org. Coating, 15, 63 (1987)], and becomes nonwettable after heat curing. However, its moisture adsorption is only 0.1% by weight, as against 3% for the latter product. This makes it a likely candidate for insulating electronic components from moisture.
Superactive and stereospecific catalysts. III. Definitive identification of active sites by electron paramagnetic resonance
Authors: Chien James C. W. , Hu Youliang
Published: April 2003

Superactive Ziegler–Natta catalysts have been prepared from a soluble MgCl2·2‐ethyl hexanol adduct in the presence of organic esters through reactions with TiCl4 and activated with AlEt3/phenyltriethoxy‐silane. Electron paramagnetic spectra (EPR) were used to elucidate the nature and amount of those Ti+3 ions not bridged to another Ti+3 ion; the chlorine bridged Ti+3 ions are EPR silent. The EPR spectra were attributed to two rhombic Ti+3 sites with principal values for the g‐tensors (1.967, 1.949, 1.915; and 1.979, 1.935, 1.887). The total amount of the EPR species, obtained by double integration of the EPR spectra, is in close agreement with the concentration of isospecific catalytic sites determined by radiotagging. This suggests that the nonspecific sites are EPR silent. When o‐phthalic ester was present during the catalyst synthesis, there appears an EPR signal at the free electron g‐value. This signal was attributed to a Ti+3 phthalate species with resonance stabilization and spin delocalization; it is absent in the catalysts made in the presence of monoesters such as ethyl benzoate. The effects of monomer, O2, H2O, and I2 on the EPR spectra were investigated. The changes in the EPR spectral intensity and the total Ti+3 ions, the latter determined by redox titrations during a polymerization or catalyst aging, are described. The results were extensively compared with those observed for supported Ziegler–Natta catalyst prepared with crystalline MgCl2.
Dithiafulvene (1,3‐dithiole): Monomers and polymers
Authors: Mulvaney J. E. , Figueroa Francisco R. , Evans Stacy B. , Osorio Fritz V.
Published: April 2003

Monomers and polymers of 2‐benzylidene‐1,3‐dithioles (dithiafulvenes) were synthesized. Polymerization of substituted dithiafulvenes with diacid chlorides, p‐phenylene diisocyanate, or terephthalaldehyde yielded yellow polymers with inherent viscosities ranging from 0.10 to 0.21 dL/g.
Preparation and properties of polyarylates and copolyarylates from phenylindanedicarbonyl chloride and bisphenols
Authors: Yoneyama Masaru , Kuruppu K. D. Athula , Kakimoto Masa‐aki , Imai Yoshio
Published: April 2003

A series of polyarylates having inherent viscosities of 0.4–1.1 dL/g was prepared by the two phase polycondensation of 1,1,3‐trimethyl‐3‐(4‐chloroformylphenyl)indanecarbonyl chloride with various bisphenols in an organic solvent–aqueous alkaline solution system in the presence of a phase transfer catalyst. Similarly, copolyarylates of high molecular weights were prepared from a mixture of the phenylindanedicarbonyl chloride, terephthaloyl chloride, and 2,2‐bis(4‐hydroxy‐phenyl)propane. All the polyarylates were characterized by their amorphous nature and high solubility in organic solvents. They gave transparent and tough films by the solution casting. The films had tensile strength of 33–46 MPa, elongation at break of 3–16%, and tensile modulus of 1.2–1.6 GPa. These polyarylates had glass transition temperatures in the range of 205–310°C, and began to decompose at ca. 350°C in air.
Synthesis of regiospecifically meta‐substituted poly(phenylacetylene)s and some of their electrical properties
Authors: Chang Tak‐lung , Holzknecht L. J. , Mark Harry B. , Ridgway Thomas H. , Zimmer Hans
Published: April 2003

The syntheses, characterizations, and electrical properties of four regiospecifically substituted poly(phenylacetylene)s are described. Tungsten(VI) chloride/tetra‐n‐butyltin (WCl6/n‐Bu4Sn) catalyst system (Higashimura–Masuda, H.–M. catalyst) was used to polymerize 3‐bromo‐, 3‐chloro‐, 3‐trimethylsilyl‐, and 3‐trimethylstannylphenylacetylenes in order to obtain high‐molecular‐weight and soluble materials. Characterizations of these polymers were done by IR and UV spectroscopic methods, GPC, DSC, and elemental analysis. The electrical conductivities of the polymers were measured on the surface of pressed pellets by a four‐point probe.
Pyrolysis–gas chromatography mass spectrometry and field ionization mass spectrometry of polyquinones
Authors: Blazso Marianne , Jakab Emma , Szekely Tamas , Plage Bernd , Schulten Hans‐rolf
Published: April 2003

Low‐ and high‐molecular mass thermal decomposition products of five polyquinones with different linking aromatic structures have been analyzed by pyrolysis–gas chromatography and by direct (in‐source) pyrolysis–field ionization mass spectrometry. The quantity of carboxyl groups present in the polymer is obtained by the amounts of carbon dioxide found by pyrolysis–gas chromatography. Assuming a radical thermal decomposition mechanism the distribution of ketoacidic and quinonoid segments along the macromolecular ladder could be estimated from the high‐molecular mass products measured by pyrolysis–field ionization mass spectrometry. A random distribution of the two different segments was found for polyquinones with biphenylene and dibenzofuran subunits, while a structure built up of blocks of two or more identical segments was obtained for polyquinones with dibenzothiophene and diphenylmethane subunits. At the same time the anomalous structural moieties in the polyquinone ladders are also clarified with the help of the identification of the unexpected pyroysis products. Oxidated and bis‐dibenzothiophene and bis‐diphenylmethane subunits were found. The observed temperature dependence for the appearances of the thermal degradation products indicates that condensation and elimination reactions are taking place under the described pyrolysis conditions. Condensation in the ketoacidic segments forming new quinonoid segments proved to be important in the polymer which was a 100% poly(ketoacid), but negligible in the polyquinones containing ketoacidic segments up to 60%.
Associative organotin polymers. I. Symmetric trialkyltin fluorides: Synthesis and properties
Authors: Dandge D. K. , Taylor C. , Heller J. P.
Published: April 2003

Four novel symmetric tri‐n‐alkyltin fluorides were prepared. In this homologous series, melting point decreases with increase in the carbon chain length while an x‐ray diffraction study shows an increase in amorphousness. 1H‐NMR spectra in cyclohexane, a nonpolar solvent in which these compounds form long polymeric chain, show a peak broadening effect due to high solution viscosity at very low solute concentration. Contrary to this, the spectra in CDCl3, a polar solvent in which these compounds are monomeric, show well resolved and narrow peaks. IR frequencies for SnC vibrations have been assigned.
A theory of green strength in polyisoprene
Authors: Cameron A. , McGill W. J.
Published: April 2003

It is shown that, at −25°C, natural rubber (NR) crystallizes more readily than synthetic polyisoprene (IR), the long induction period for nucleation in IR in particular being dependent on the carbon black loading. Both elastomers form bound rubber with carbon black but not with nonreinforcing fillers such as CaCO3 and glass powder. At room temperature, in the presence of carbon black, NR has good green strength but not IR, while neither rubber has good green strength with nonreinforcing fillers. However, at 0°C CaCO3 filled NR too has good green strength. A theory is proposed to account for the good green strenth characteristics found with certain compounds. In the model rubber molecules, already bound to the carbon black surface, are linked together, at low strains, via stress‐induced crystal lamellae, giving a three‐dimensional network in the compound. Such crystal lamellae are known to grow at right angles to the direction of strain from row nuclei formed at low strains. The coherence provided by the network permits the formation, at higher strains, of stress‐induced crystals in which polymer chains are now aligned in the direction of strain. This leads to an upturn in the stress–strain curve. In the absence of either bound rubber or of crystal lamellae, a long range network structure cannot form and extension of the sample continues at constant stress.
Synthesis and characterization of poly(amide‐sulfonamide)s
Authors: Adduci Jerry M. , Amone Michael J.
Published: April 2003

Novel poly(amide‐sulfonamide)s have been prepared by reacting terephthaloyl, isophthaloyl, and sebacoyl chloride with variously substituted dianilines containing preformed sulfonamide linkages. Inherent viscosities of the prepared polymers ranged from 0.19 to 0.58 dL/g. Despite low apparent viscosities, the polymers had film forming properties. Clear, tough, flexible films were obtained from the prepared polymers, in particular the poly(terephthalamide‐sulfonamide)s. Glass transition temperatures, determined by differential scanning calorimetry, ranged from 84 to 247°C. Thermogravimetric analyses of the polymers showed that they have moderate thermal stability with weight losses ranging from 12 to 35% at 350°C.
Second‐order kinetics of enthalpy recovery in polystyrene
Authors: Chang Benjamin Tai‐An , Li J. C. M.
Published: April 2003

Second‐order kinetics were found applicable to the isothermal enthalpy release after quenching from a high temperature. The kinetic behavior was unaffected by different amounts of initial excess enthalpy. The activation enthalpy obtained from the temperature dependence of the second order rate constant was 200 kcal/mol or 837 kJ/mol which could be compared with 736 kJ/mol for volume recovery in a similar temperature range relative to Tg.
Analysis of plasma polymerization of allylamine by FTIR
Authors: Krishnamurthy V. , Kamel Ihab L. , Wei Yen
Published: April 2003

The plasma polymerization of allylamine in an inductively coupled rf plasma reactor is analyzed by Fourier transform infrared spectroscopy. Comparison of the infrared spectra of the as‐received monomer and the plasma polymerized film reveals a conversion of the primary amine in the monomer (CH2NH2) to an imine (CHNH) and a nitrile (CN). Plasma polymerization of ethylenediamine yields the same results, suggesting that this polymerization scheme may be typical of primary amines. Increasing the plasma power seems to increase the proportion of nitrile groups in relation to the imine groups. The infrared spectra of the vapor phase polymerized monomer was similar to that of the substrate‐grafted allylamine film implying a similar structure. Aging of this vapor phase polymer at 120°C for 1 h in vacuum and at 295°C for 15 min in an oxygen free environment reveals nitrile group reaction similar to that observed in polyacrylonitrile. Thermogravimetric analyses of the vapor phase polymers in a nitrogen atmosphere at 20°C/min demonstrated the thermal stability, with the polymer produced at a plasma power level of 50 W retaining 20% of its weight at 1000°C. This was better than the stability shown by the polymer produced at 150 W and is attributed to the ease of nitrile group polymerization in the former.
Synthesis of poly(methyl methacrylate) macromonomer
Authors: Ishizu Koji , Fukutomi Takashi
Published: April 2003

Anionic polymerization of methyl methacrylate (MMA) was carried out in tetrahydrofuran (THF) or THF/toluene mixture at −78°C initiated by triphenylmethyl sodium or lithium as initiators. Highly syndiotactic PMMA of low polydispersity (Mw/mn = 1.11–1.17) could be prepared with triphenylmethyl lithium in THF or THF/toluene mixture at − 78°C. Moreover, PMMA macromonomer having one vinylbenzyl group per polymer chain was prepared by the couplings of living PMMA initiated by triphenylmethyl lithium with p‐chloromethyl styrene (CMS) at −78°C. The coupling reaction of living PMMA initiated by triphenylmethyl sodium with CMS was scarcely occurred.
Wavelength sensitivity of acrylonitrile–butadiene–styrene
Authors: Searle N. D. , Maecker N. L. , Crewdson L. F. E.
Published: April 2003

The wavelength sensitivity of unpigmented 100 mil thick ABS exposed to sunlight and filtered xenon are radiation was determined by the sharp cut filter technique based on three types of photochemical changes: bleaching, yellowing and loss in impact strength. Bleaching of the yellow‐colored species formed in the processed material is caused by wavelengths between 380 and 525 nm with maximum color change by the 475–485 nm region. Photochemical yellowing is due to wavelengths between 300 and 380 nm with all wavelengths being almost equally effective. The spectral sensitivity based on change in impact strength shifts from the UV to the visible region as photochemical yellowing progresses. Addition of two stabilizers, a benzotriazole ultraviolet absorber and a hindered amine stabilizer, shifts the wavelength sensitivity based on yellowing to wavelengths shorter than 330 nm, but has no influence on the spectral effects based on impact strength. It is postulated that the rate of yellowing is reduced mainly by the ultraviolet absorber and stabilization against loss in impact strength is due largely to the hindered amine. Differences in rates and spectral response of the three types of photochemical changes indicate that they are due to different initiating mechanisms and thus require different types of stabilization. The significance to stability testing is discussed.
Molecular motions of tactic poly(2‐hydroxyethyl methacrylate) in solutions studied by 13C‐NMR relaxation measurement
Authors: Oh Seok Heon , Ryoo Ryong , Jhon Mu Shik
Published: April 2003

The spin‐lattice relaxation time and the nuclear Overhauser enhancement were measured using Bruker AM 300 spectrometer operating at 75.5 MHz for 13C to investigate the molecular motional characteristics and its tacticity effect for tactic poly(2‐hydroxyethyl methacrylate) (PHEMA) as a function of temperature in dimethyl sulfoxide and methanol solvents. The observed relaxation data have been analyzed for both backbone motion and methyl internal rotation according to the log‐χ2 distribution model and the diamond‐lattice model. The correlation times thus obtained for the molecular motions show that isotactic PHEMA is more flexible than syndiotactic counterpart. The syndiotactic PHEMA seems to have intramolecular hydrogen bonding which restricts the motion of C‐2 carbon at temperatures below 35°C, whereas the isotactic one indicated no hydrogen bonding at all temperatures examined in this study. The methyl group of isotactic PHEMA shows a greater degree of freedom for the internal rotation than that of syndiotactic one. From the temperature dependence of correlation times, the activation energies for both backbone segmental motion and methyl internal rotation are obtained. The activation energies, 20 kJ/mol for backbone motion and 19 kJ/mol for methyl internal rotation, for isotactic PHEMA are substantially lower than the corresponding activation energies of 30 and 32 kJ/mol obtained for syndiotactic one. An examination of these energies indicates that methyl side group and backbone motions in tactic PHEMA are linked together.
Synthesis, characterization, and kinetics studies of organic soluble photosensitive copolyimide
Authors: Lee Hurng‐Rern , Lee Yu‐Der
Published: April 2003

A copolyimide synthesized from 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride, 3,5‐diaminobenzoic acid, and 2,3,5,6‐tetramethyl‐p‐phenylene diamine was found to be soluble in N‐alkyl substituted amides. An organic soluble photosensitive polyimide was obtained by further reaction of the copolyimide with methacrylic acid glycidyl ester. After adding Michler's ketone, the UV spectra absorbance near 360 nm of the copolyimide decreased rapidly upon the irradiation of mercury lamp. Using benzoic acid and methacrylic acid glycidyl ester as model compounds and N, N‐dimethylbenzylamine as catalyst, the mechanism of reaction between the carboxylic group of the copolyimide and epoxy group of methacrylic acid glycidyl ester in N‐methyl‐2‐pyrrolidone was found to have two competitive reactions, namely the auto‐catalytic and the catalytic reactions. The apparent rate constants of each reaction were determined. Comparison of apparent rate constants between the model compound and the polymer reaction system are also reported.
Magnesium chloride supported catalysts for olefin polymerization. XIX. Titanium oxidation states, catalyst deactivation, and active site structure
Authors: Chien James C. W. , Weber Siegfried , Hu Youliang
Published: April 2003

A precise method for the determinations of Ti+2, Ti+3 and Ti+4 was developed. The CW‐procatalyst before activation contains mostly Ti+4 ions with 6% Ti+3 and 4% Ti+2 ions. Activation with AlEt3 alone at room temperature reduced all the titaniums to lower valence states consisting of 71% Ti+3 and 29% Ti+2. Reduction is incomplete when methyl‐p‐toluate was present as external Lewis base during activation: at 25°C the distribution of Ti+4 : Ti+3 : Ti+2 is 36% : 25% : 38%; the distribution at 50°C is 37% : 22% : 40%. Aging of the activated catalyst caused little or no changes in the distribution of [Ti+n]; whereas the catalytic activity decays rapidly with aging. The aged catalysts have polymerization activity comparable to the decreased activity of the catalyst during a polymerization. The [Ti+n] was determined for the CW‐catalyst during the course of a decene polymerization; they were found to be Ti+4 : Ti+3 : Ti+2 = 30% : 27% : 43%, which did not change with polymerization time. These results suggest that the reducibility of Ti+4 species by AlEt3 or 3AlEt3/MPT to different valence states is predicated by their structures. These species do not undergo further changes in their oxidation states during either aging or polymerization. Their decays probably involve nonreductive metathesis reactions like those known for zirconium alkyls. Possible structures for the stereospecific and nonspecific sites are proposed.
Laser‐initiated polymerization of lauryl methacrylate: Laser repetition rate effect
Authors: Hoyle Charles E. , Trapp M. A. , Chang C. H.
Published: April 2003

The photoinitiated polymerization of lauryl methacrylate with a pulsed excimer laser source is highly dependent on the laser repetition rate and the absorbance (optical density) of the photoinitiator. The GPC chromatograms of poly(lauryl methacrylate) generated by the laser‐initiated polymerization of lauryl methacrylate decrease in size and shift to lower molecular weight species with increasing repetition rate. In addition, the polymers produced at high laser repetition rates are characterized by a number of distinct narrow molecular weight GPC peaks. The decrease in polymerization efficiency is especially pronounced at laser pulsing frequencies greater than 3 Hz.
Structure of macronet styrene polymer as studied by inverse steric exclusion chromatography and by selective sulfonation
Authors: Jeřábek K. , Setínek K.
Published: April 2003

The structure of macronet styrene polymer in original, partially sulfonated and fully sulfonated form was studied using inverse steric exclusion chromatography. By alternative measurements of the partially sulfonated sample in water and in tetrahydrofuran, it was possible to characterize separately sulfonated and unsulfonated domains. It was found that the polymer contains 10–15% of highly expandable polymer mass and the rest is formed by much more dense polymer skeleton.
Effect of γ‐ray and photoirradiation on very low density polyethylene
Authors: Geetha R. , Torikai A. , Yashida S. , Nagaya S. , Fueki K.
Published: April 2003

The fourth type of polyethylene—very low density polyethylene (VLDPE)—has been developed very recently. VLDPE is a copolymer of ethylene and 1‐butene. The radiation and photo degradation of VLDPE was studied using gel, FT‐IR, and UV spectral measurements. Mechanical tests were also done; the rate of gel and carbonyl formation was high. End methyl CH3 group was found to increase in the case of radiation degradation. The initial modulus was very low indicating the rubbery nature in the copolymer. VLDPE was found to be highly resistant to radiation‐induced degradation than linear low density polyethylene. VLDPE is highly susceptible to thermal effects.