bluuebunny/crossref_metadata_2025 huggingface dataset:
Crosslinked polymers of styrene with 1,3,5‐triisopropenylbenzene
Authors: Furlani A. , Bicev P. , Fiorentino M.
Published: April 2003

Crosslinked polymers of improved properties compared to those of pure polystyrene, are obtained by the thermal or radical copolymerization of styrene with 1,3,5‐triisopropenylbenzene. The copolymers are transparent glassy solids, practically insoluble in most organic solvents and easily machineable. They decompose at about 350°C. Copolymers containing 5–30% of 1,3,5‐triisopropenylbenzene exhibit the better properties.
Radiation‐induced emulsion polymerization of ethylene. V. Copolymerization of ethylene with hexafluoropropylene
Authors: Senrui Shiro , Ito Masayuki , Takehisa Masaaki
Published: April 2003

The emulsion copolymerization of ethylene with hexafluoropropylene was studied by using 60Co γ‐radiation as the initiator. The apparent rate of copolymerization is proportional to the 1.6 power of ethylene fugacity. The activation volume was calculated from the pressure dependence of the apparent rate constant of copolymerization and was −30 ml/mole, which is smaller than the value reported by Wada et al. for ethylene polymerization in tert‐butyl alcohol. The copolymer produced had a broad composition from ethylene‐rich to alternative. As expected, the former was a crystalline, polyethylenelike copolymer, but the latter was an amorphous and rubberlike copolymer. The glass transition temperature of the copolymers increased with an increase in hexafluoropropylene content. The thermal degradation temperature in an atmosphere of nitrogen decreased slightly with introduction of hexafluoropropylene in polyethylene, but the thermal degradation behavior in air was complicated by the introduction of hexafluoropropylene.
Synthesis and some properties of poly‐(2,5‐trimethylene benzimidazole) and poly‐(2,5‐trimethylene benzimidazole hydrochloride)
Authors: Aharoni Shaul M. , Litt Morton H.
Published: April 2003

A polymer, poly(2,5‐trimethylene benzimidazole), the first of a new family of nonsymmetrical polymers, was synthesized via an eight‐step synthetic route. The polymer, obtained by melt polymerization, is amorphous and in its neutral form behaves as a moderate insulator. It forms 1 : 1 HCl adducts. When cast from formic acid solution, it forms 1 : 1 formic acid adducts. The acid adducts are semiconductors with resistivities in the 106–108 ohm‐cm range. Space‐charge effects are generated in the adducts as carrier mobility rises.
Thermoxidative degradation leading to gel in poly(ethylene terephthalate)
Authors: Spanninger Philip A.
Published: April 2003

Poly(ethylene terephthalate) oxidizes on heating at 300°C in an air stream. Various literature has cited crosslinking under such conditions through a butanetriol or a biphenyltricarboxylic acid. In this study gelled polymer was found to contain the latter trifunctional compound, but not the former. In addition, 4,4′‐biphenyldicarboxylic acid was found in the degraded gel. There is further indication for the presence of other multifunctional species. All components are consistent with general free‐radical arylation mechanisms.
Synthesis and thermal properties of a new class of high‐temperature polyamides from hexahydrobenzodipyrrole
Authors: Doddi Namassivaya
Published: April 2003

A series of polyamides was synthesized by the interfacial polycondensation of 1,2,3,5,6,7‐hexahydrobenzo [1,2‐c:4,5‐c′] dipyrrole with isophthalic, terephthalic, oxydibenzoic, sebacic and adipic acid chlorides. High molecular weight polymers with inherent viscosities ranging from 0.4 to 2.3 dl/g were obtained. Polymerization with isophthaloyl chloride gave the highest molecular weight polymer in this series. These polyamides melt between 350°C and 475°C, depending on structural differences as determined by differential scanning calorimetry (DSC). Rapid weight loss in these polymers was observed in the range of 350–400°C under thermogravimetric analysis in a nitrogen atmosphere. All these polyamides are susceptible to photooxidative degradation. The results were compared with Nomex polymer poly(1,3‐phenylene isophthalamide).
Chain transfer studies of alternating copolymerization
Authors: Funt B. Lionel , Rhodes Heather E. W.
Published: April 2003

Dimethylaniline (DMA) induces chain transfer in the zinc bromide‐complexed donor–acceptor polymerizations of styrene–acrylonitrile to form alternating copolymers. The Mayo plots are linear, but the rates decrease with increase in DMA and degradative chain transfer occurs. Although conventional free‐radical transfer agents have negligible effect on the rates or molecular weights, a twentyfold reduction of molecular weight is obtained with DMA. Spectroscopic data indicate the formation of an equimolar complex of DMA and ZnBr2, but the lowering of molecular weight is not attributable to the reduction of the effective ZnBr2, concentration. A possible mechanism involving a competition between [ZnBr2(DMA)2] and [ZnBr2,DMA,AN] is suggested.
Influence of covalently bonded dyes on the photooxidative destruction of poly(vinyl alcohol)
Authors: Kalontarov I. Ya. , Kostina N. V. , Kiseleva N. N.
Published: April 2003

The influence of the dye and type of polymer bond on the rate of photo‐oxidation in poly(vinyl alcohol) (PVA) films was investigated. C. I. Reactive Yellow 4 and C. I. Reactive Blue 4 dyes and their inactive forms were used as ultraviolet light absorbers. It was shown that in the case of PVA samples dyed with these dyes, the processes of structurizing due to the secondary reactions take place, as it can be supposed on the basis of the changes in the radical concentration yield and growth of intrinsic viscosity. The kinetics of PVA photo‐oxidative destruction was investigated by ESR and infrared spectroscopy methods. The loss of strength under photodestruction was checked viscometrically.
Polyamine polymers from active hydrogen compounds, formaldehyde, and amines
Authors: Tomono Tsugikazu , Hasegawa Etsuo , Tsuchida Eishun
Published: April 2003

Active hydrogen compounds such as hydroquinone (HQ), cyclohexanone (CH), acetophenone (AP), and 4,4′‐methylene bis‐N‐methylaniline (MNA) polymerized with formaldehyde (F) and secondary diamines to produce Mannich base polyamine polymers. The HQ‐containing polymers were oxidized to benzoquinone (BQ)‐containing polymers and their redox properties were investigated in the desulfurization of hydrogen sulfide.
Applications of ESCA to polymer chemistry. IV. The composition and structure of copolymers of ethylene with tetrafluoroethylene
Authors: Clark D. T. , Feast W. J. , Ritchie I. , Musgrave W. K. R. , Modena M. , Ragazzini M.
Published: April 2003

Molecular core binding energies have been measured by ESCA for a series of copolymers of tetrafluoroethylene and ethylene. Detailed analysis of the results demonstrates the utility of ESCA for determination of copolymer compositions and for providing information on important structural features for these copolymers.
Anionic polymerization of a series of five‐membered cyclocarbosiloxanes
Authors: Suryanarayanan B. , Peace B. W. , Mayhan K. G.
Published: April 2003

A study was conducted of the anionic polymerization of a series of methyl‐ and/or phenyl‐substituted five‐membered cyclocarbosiloxanes. The polymerization was initiated by lithium n‐butyldiphenylsilanolate in the presence of tetrahydrofuran. The rate of conversion of monomer to polymer was measured in an NMR spectrometer. The rate of polymerization was largely dependent upon the structure of the growing chain ends. The apparent activation energies were in the range 10–14 kcal/mole for the series.
Photoreversible reactions of poly(vinyl cinnamylideneacetate) and its model compound
Authors: Tanaka Hideaki , Otomegawa Eiich
Published: April 2003

Photochemical reactions of poly(vinyl cinnamylideneacetate) and its model compound were studied. The irradiation of these compounds with light of wavelength longer than 300 nm produced dimeric forms of cinnamylideneacetyl groups, which were effectively dissociated into the monomeric forms by the irradiation with 254 nm light.
Some applications of gel‐permeation chromatography in investigations of structure and the solution properties of radical‐initiated poly(vinyl chloride)
Authors: Kolínský M. , Janča J.
Published: April 2003

The applicability of the published universal calibration parameters for gel‐permeation chromatography on polystyrene standards and poly(vinyl chloride) samples with a defined structure has been compared. It was shown experimentally that of several theoretically possible molecular weight averages attributed to the elution volume at the position of the peak maximum, the root mean‐square average molecular weight MRms = (MwMn)0.5 shows the best accordance. The molecular weights obtained by gel‐permeation chromatography were compared with those determined by viscometry, osmometry, and the light‐scattering method. The reproducibility of gel‐permeation chromatography measurements is 3%, and the average variance of the results as compared with results obtained by the above methods is about 8%. It was also found that the gel‐permeation chromatography does not involve any anomalies interfering with results obtained by other methods.
An electrochemical route to phenol–formaldehyde precursors
Authors: Phillips D. C. , Meier J. F. , Jackson J. A.
Published: April 2003

With the aid of VPC and NMR, the electroinitiated polymerization of phenol or p‐tert‐butyl phenol with formaldehyde in the presence of basic electrolytes has been investigated over a range of current densities. Results from an electroinitiation study were contrasted with base‐catalyzed thermal polymerizations and, except for yield, found to be essentially invariant. GPC of the electroinitiated and thermally polymerized resins indicates similar results with low molecular weight species of relatively narrow molecular weight distribution being the principal products. An electroinitiation mechanism, in agreement with the mechanism for base‐catalyzed thermal polymerization is proposed to describe these experimental results.
Radical polymerization of metal‐coordinated monomers with ligands of pyrrole‐containing schiff bases
Authors: Tsuchida Eishun , Tomono Tsugikazu , Honda Kenji
Published: April 2003

The copper complexes and the cobalt complex with the ligand of 3‐(2‐pyrrolylmethyl‐enimino)propene‐1 (PIP) or p‐(2‐pyrrolylmethylenimino)styrene (PIS) were synthesized and homopolymerizations and the copolymerization with styrene, acrylonitrile, methyl methacrylate and acrylic acid studied. In the polymerization of chelate monomers, inhibition of radical polymerization by the central metal ion was observed, but the chelate polymer could be obtained only if the initiator was present in higher concentrations in the feed. It is considered that the strength of inhibition depends on the electronic configuration of d‐orbitals of the central metal ion. The initiation mechanism of the cupric chelate monomer may be reduction of the metal ion by the redox reaction with a primary radical via the intramolecular electron transfer through the π‐conjugated system of the ligand prior to the propagation step. This mechanism was verified by studying the redox reaction of various copper complexes with DPPH. In the system of the copper complex containing PIS and acylic acid the alternating copolymer could be obtained at any mole fraction of monomer mixture in feed.
Cyclopolymerization of isoprene with VCl4–AlEt2Br catalyst system
Authors: Gandhi V. G. , Deshpande A. B. , Kapur S. L.
Published: April 2003

Isoprene was polymerized at 30°C with VCl4–AlEt2Br catalyst system in n‐hexane. A linear dependence of rate of polymerization on the monomer and catalyst concentrations was found. The overall activation energy was 8.96 kcal/mole. Infrared spectra of polyisoprene showed the presence of cyclic structure, indicating a cationic mechanism of polymerization.
Absorption of polymers at the solution–solid interface. XII. Stabilization of dispersed silica by absorbed styrene–methyl methacrylate copolymers
Authors: Barron M. J. , Howard G. J.
Published: April 2003

The ability of styrene–methyl methacrylate copolymers to stabilize silica dispersions has been investigated. Random, block, and graft copolymers covering the entire composition range have been employed in carbon tetrachloride, trichloroethylene, and benzene solutions. Equilibrium sediment volumes and dispersion turbidities provide adequate and concordant estimates of stabilization efficiency. Polystyrene is not adsorbed by precipitated silica from trichloroethylene or benzene and does not stabilize dispersions in these liquids; although adsorbed from carbon tetrachloride, there is no stabilization. Poly(methyl methacrylate) is an efficient dispersion stabilizer, and its performance is independent of molecular weight over a wide range. Random copolymers having styrene contents in excess of ca. 60% do not stabilize in trichloroethylene but do so in carbon tetrachloride, although well adsorbed in both cases. With this major exception, and that of a low‐styrene graft copolymer in carbon tetrachloride, copolymers of all structures and compositions stabilize well, better than poly(methyl methacrylate) in the solvents examined. A substantial degree of surface coverage is necessary for optimum stabilization. Subsidiary solution adsorption and layer thickness measurements are also reported.
Modification of poly(vinyl chloride). XXIV. Graft polycondensation of p‐(2‐chloroethyl)thiophenol on poly(vinyl chloride)
Authors: Mori Kunio , Nakamura Yoshiro
Published: April 2003

A new graft reaction, the graft polycondensation of p‐(2‐chloroethyl)thiophenol (CETP) onto poly(vinyl chloride) (PVC) in ethylenediamine (EN) and its mixed solvents was studied under various graft conditions. Two graft procedures which is different with addition operations of CETP were tried. The per cent grafting G and the grafting efficiency E in procedure A were generally higher than those in procedure B. G and E also increased with increase in temperature and time. The increase of the weight of PVC and in the concentration of CETP increased G and E, respectively. Mixed solvents composed of EN and benzene, tetrahydrofuran, or dimethylformamide also increased G and E. The grafted products thus obtained have a gel fraction and contain nitrogen. However, on grafting in the presence of C12H25SH, higher G′ and E′ were obtained, and the products contained no gel fraction or nitrogen. The degree of polycondensation and the number of grafts in the grafted PVC were about 4–12, and 0.64–1.71 mole‐%, respectively, as estimated from elemental analysis.
Structure and reactivity in cationic polymerization of butadiene derivatives. II. 1‐phenylbutadiene
Authors: Masuda Toshio , Otsuki Michihisa , Higashimura Toshinobu
Published: April 2003

The reactivity of 1‐phenylbutadiene (1‐PBD) in cationic polymerization and the monomer structure were investigated. 1‐PBD polymerized at −78°C in several solvents initiated by cationic catalysts such as stannic chloride and tungsten hexachloride. The polymerizations proceeded predominantly via 3,4‐type propagation mode, and gave low molecular weight polymers. More than one double bond of 1‐PBD was consumed during the polymerizations, probably due to transfer and cyclization reactions. 1‐PBD was several times as reactive as styrene and trans‐1,3‐pentadiene in copolymerizations. The Hammett plots of reactivities of ring‐substituted 1‐PBD in cationic polymerization gave the p‐value of ‐1.20, which is 0.6 times that of styrene. The 1H and 13C NMR chemical shifts of ring‐substituted 1‐PBD were measured and discussed in relation to the reaction mechanism.
Effect of polymer on electron‐donating character of polymer donor. II. Formation of charge‐transfer complex between polymers containing N‐dimethylaniline group and trinitrotoluene
Authors: Iwatsuki Shouji , Inukai Ken‐Ichi
Published: April 2003

Formation of charge‐transfer complexes with trinitrotoluene (TNT) as a common acceptor was studied in detail by using dimethyltoluidine (DMT), poly‐N‐dimethyl‐p‐aminostyrene (poly‐ASt), and also copolymers of aminostyrene (ASt) and styrene (St) as donors. A smooth bathochromic shift in λmax was observed with increasing ASt unit content in copolymers. Values of the constant for charge transfer complex formation KCT were found to increase smoothly with ASt unit content. However, the KCT value with DMT did not coincide with the value extrapolated from the plot of KCT value versus ASt unit content to zero ASt unit content, but was found to be much higher than the limiting value, in contradiction to the results obtained with maleic anhydride (MAnh). The entropy of complex formation with DMT was found to be exceptionally small; this small value may be responsible for the high KCT value with DMT.
γ‐radiolysis of ketone polymers. III. Copolymers of ethylene and carbon monoxide
Authors: Slivinskas J. A. , Guillet J. E.
Published: April 2003

The γ‐radiolysis of copolymers of ethylene and carbon monoxide (CO‐PE) containing 0–9 wt‐% of CO has been studied in the solid phase under vacuum with respect to hydrogen production, scission, and crosslinking. In this regard, the introduction of carbonyl groups into polyethylene increased both the scission and crosslinking efficiency. However, a theoretical statistical treatment for random scission and crosslinking, which was used to calculate G(s) and G(x) yields, predicted gelation with irradiation dose; this was confirmed experimentally. The increased G(x) values are attributed to the localization of absorbed energy in the carbonyl group arising from preferential trapping of thermalized secondary electrons. A stoichiometric balance is shown to be consistent with the reduction of one carbonyl group to a secondary alcohol per excess crosslink observed. The G(H2) yield is reduced by the presence of ketone groups to a level which is in close agreement with the yield obtained for the model ketone 12‐tricosanone. This quenching of H2 production is explained by intramolecular electronic energy transfer along the chain to the carbonyl group with concomitant intermolecular charge transfer between neighboring molecules.
TGA–MS degradation studies of some new aliphatic–aromatic polybenzimidazoles
Authors: Tsur Yoel , Freilich Yitzchak L. , Levy Moshe
Published: April 2003

The degradation of a series of polybenzimidazoles containing metylene groups in the chain was studied by TGA and MS. On heating the polymer derived from m‐phenylenediacetic acid and 3,3′‐diaminobenzidine to about 560°C in argon, partial fast decomposition into a solid sublimate was observed. The sublimate consisted of a mixture of fractions derived from the breaking of the chain at the methylene bonds. These methylene groups can be preoxidized at 250°C to carbonyl groups, eliminating thereby this mode of decomposition. At temperature higher than 560°C, gaseous products similar to those of the corresponding all‐aromatic PBI are obtained.
Photolysis of poly(ethyl acrylate) and poly(n–butyl acrylate) in vacuo
Authors: McGill W. J. , Ackerman L.
Published: April 2003

Thin films of poly(ethyl acrylate) and poly(n‐butyl acrylate) were decomposed in vacuo by means of a high pressure Hg lamp, and the rate of development of volatile products was measured. The main gaseous products were CO, CO2, and the alcohol, aldehyde, alkane, and formate derived from the respective ester groups. In addition poly(ethyl acrylate) evolved acetal as well as ethyl propionate, while n‐butyl valerate was evolved from poly(n‐butyl acrylate) only after prolonged exposure. All products and the principal features of the decomposition are discussed.
ESCA investigation of the electronic structure of polyhexafluorobut‐2‐yne
Authors: Chambers R. D. , Clark D. T. , Kilcast D. , Partington S.
Published: April 2003

Polyperfluorobut‐2‐yne is prepared by a fluoride ion‐induced polymerization of hexafluorobut‐2‐yne. The mass spectrum indicates a regular fragmentation pattern but the ESCA spectrum establishes the structure as a polyene, rather than a crosslinked system, and the occurrence of a shake‐up peak assists in this assignment.
Preparation and characterization of alternating copolymer of α‐methylstyrene and acrylonitrile made with zinc chloride–peroxide catalysis
Authors: Kuntz Irving , Chamberlain Nugent F.
Published: April 2003

The copolymerization of the zinc chloride complex of acrylonitrile in excess acrylonitrile with α‐methylstyrene in the presence of lauroyl peroxide is described. Elemental and proton NMR analyses indicate the equimolar nature of the copolymer product. 13C NMR examination shows that this copolymer is alternating in structure and suggests that the steric placements of the copolymer are random in nature; that complexation does not lead to a stereoselective enchainment mode is the implication of our results. A copolymer which appears to be similar to our product has been prepared by other workers using Al(C2H5)1.5Cl1.5 complexation. Our conclusions regarding copolymer stereoregularity differ from theirs.
Preparation and photolysis of poly‐p‐methoxyacrylophenone and its copolymers with styrene and methyl methacrylate
Authors: Lukáč I. , Moravčíak M. , Hrdlovič P.
Published: April 2003

Poly‐p‐methoxyacrylophenone (PPMeOAP) and its copolymers with styrene (PMe‐OAP–S) and with methyl methacrylate (PMeOAP–MMA) were prepared. The photolysis in solution with 313 and 366 nm radiation was followed viscometrically. In solvents such as chlorobenzene and ethyl benzoate, random main‐chain scission from n–π* excited triplet state occurs. The lowest excited triplet state in formic acid and in ethylene chlorhydrin is of the character π–π*, from which no main‐chain scission occurs. In solvents in which destruction occurs, the main‐chain scission is retarded by triplet quenchers, such as naphthalene, 2,5‐dimethyl‐2,4‐hexadiene, and biphenyl. Quenching experiments indicate that the lifetime for the excited triplet state of PPMeOAP is 25 times that for polyacrylophenone. In PMeOAP–MMA copolymers, quantum yields of main‐chain scissions were lower and lifetimes of excited triplets were longer than in PPMeOAP, due to hindered intramolecular photoreaction.
Structure–property relationships in polyamides containing cyclohexylene or phenylene structures
Authors: Ridgway James S.
Published: April 2003

Polyamides were prepared from linear, aliphatic dicarboxylic acids of six to twelve carbon atoms with 1,4‐cyclohexanebis(methylamine), 1,4‐cyclohexanebis (ethylamine), p‐xylylenediamine, and p‐phenylenebis(ethylamine). Melting points, glass transition temperatures, densities, and moisture regains were compared for the polymers to determine the relative effect of the cyclohexylene and phenylene linkages. While polyamides containing the trans‐cyclohexylene group possessed higher glass transition temperatures than their aromatic counterparts, melting behavior was not as consistent. The odd‐even rule, which states that polyamides with an even number of methylene linkages between the ring and the functional group melt higher than those with an odd number of such linkages, was violated in the cycloaliphatic systems. The Tg of ring‐containing polyamide fibers was not dependent solely upon ring concentration, but was influenced by the molecular fit of the ringed intermediate in the polymer chains. Molecular fit appears to affect the Tg and melting point of alicyclic polyamides to a greater extent than the aromatic analogs. Differences in Tg, both within and among the polymer series, was not explained by either density or the degree of crystallinity.
Radiation‐induced emulsion copolymerization of tetrafluoroethylene with propylene. III. Polymerization mechanism
Authors: Suzuki Nobutake , Matsuda Osamu , Okamoto Jiro
Published: April 2003

In the radiation‐induced emulsion copolymerization of tetrafluoroethylene with propylene, the dose rate dependence, the effect of emulsifier concentration, and the effect of monomer composition were studied. The rate of polymerization was proportional to the 0.90 power of the dose rate and the 0.26 power of the emulsifier concentration. The degree of polymerization was independent of the dose rate and the emulsifier concentration. Both the rate of polymerization and the degree of polymerization increased with tetrafluoroethylene content in the monomer mixture. The resulting copolymer was an alternating polymer over a wide range of monomer composition. It was concluded from the dose rate dependence of the rate of polymerization that the emulsion copolymerization is mainly terminated by degradative chain transfer of the propagating radical to propylene.
Structure and reactivity in cationic polymerization of butadiene derivatives. III. 2‐phenylbutadiene
Authors: Masuda Toshio , Mori Toshiaki , Higashimura Toshinobu
Published: April 2003

Cationic polymerization of 2‐phenylbutadiene (2‐PBD) has been investigated. Polymerization were performed by SnCl4·TCA, WCl6, and BF3·OEt2 as catalysts in methylene chloride. 2‐PBD polymerized easily and gave low molecular weight polymers. The polymerization proceeded to give a polymer having 1,4‐structure without 1,2‐ or 3,4‐structure. The double bonds of the polymer were partially consumed, probably owing to cyclization and chain‐transfer reactions. 2‐PBD was 0.66 times as reactive as styrene and 1.2 times as reactive as isoprene in the copolymerization at −78°C by SnCl4·TCA in methylene chloride. Reactivities of ring‐substituted 2‐PBD obeyed the Hammett relation with ρ+ = −2.04. The 13C chemical shift of ring‐substituted 2‐PBD was measured. Chemical shift values for C1 and C3 were correlated with Hammett σ, but those for C2 and C4 were almost unaffected by the substituents. On the basis of experimental results, the transition state of the cationic polymerization of 2‐PBD was depicted as a benzylic cation rather than a phenylallylic one.
Interaction of monovalent and divalent counterions with some carboxylic polysaccharides
Authors: Rinaudo M. , Milas M.
Published: April 2003

Eleven samples of carboxylic polysaccharides were studied. The activity coefficients γ have been measured for monovalent (Na+) and divalent (Ca2+) counterions. There is no specific influence of the structure of the chain on γ values. Agreement with theoretical values confirms the rigidity of the chain; for low charge density, the theoretical treatment seems to be incorrect. Selectivity is discussed in term of selectivity coefficient K and free energy of exchange ΔG; ΔG is linearly related to the charge density but K which characterizes the competition of the two counterions is sensitive to the nature of the chain. The carboxymethylamyloses present a larger selectivity whose origin is not discussed here. The last point treated is the intrinsic constant of dissociation of polyacids. The pK0 values are practically independent of the nature of the polyelectrolyte and of the charge density; the values are close to the pK0 of monomeric unit and are not affected by the position of COOH in the anhydroglucose ring.
Interaction of organo‐alkali compounds with unsaturated hydrocarbons
Authors: Podolsky A. F. , Taran A. A.
Published: April 2003

The stability of disodium tetramer of α‐methylstyrene (“living” polymer) in THF and in a THF‐α‐methylstyrene mixture has been investigated by spectrophotometry. It was found that at 25°C and at concentrations lower than the equilibrium concentration α‐methylstyrene greatly stabilizes the process leading to disappearance of the main absorption band (λmax = 340 mμ) of “living” polymer. In this case isomerization of “living” polymer is accompanied by quantitative conversion of the compound having λmax = 340 mμ into a new compound with λmax = 430 mμ. The constants of the disappearance rate D340 and the activation energies of the process were determined in THF and in a THF‐α‐methylstyrene mixture. The introduction of small amounts of α‐methylstyrene into living polymer at 25°C markedly increases its activity in the course of propagation. The experimental results are considered from the standpoint of formation of complexes of living polymer with α‐methylstyrene.
Radiation‐induced crosslinking and cyclization in 1,2‐polybutadiene
Authors: Von Raven A. , Heusinger H.
Published: April 2003

In order to get information on the radiolytic changes in 1,2‐polybutadiene (1,2‐PB) the sol and gel fractions, the conversion of double bonds, the structure and concentration of radicals, the formation of dienes and the formation of gaseous products were measured. In addition, the dose rate dependence and temperature dependence for the conversion of double bonds were determined. G values for double bond conversion depend on molecular weight and range from 20 to 200. G values for crosslinking are about 10. A mechanism for the double bond conversion is proposed which involves initiation by a transformation of the primary radical ion in the vinyl group into a carbonium ion and a radical. This is supported by ESR measurement. Reaction of the carbonium ion with a vinyl group in the same chain gives rise to cyclization, whereas reaction with a vinyl group in a neighboring chain results in crosslinking. A comparison of the G values for conversion of double bonds with the G values for crosslinking shows that the formation of cyclic rings exceeds the formation of crosslinks by a factor of about 10. The corresponding values in 1,4‐cis‐ and 1,4‐trans‐polybutadiene are much smaller [G(cl) ≃ 2; G(db) ≃ 7]. The pendent vinyl groups in 1,2‐polybutadiene therefore are more reactive than the vinylidene groups in 1,4‐polybutadienes.
Metal compounds in free‐radical processes. III. Polymerization of acrylonitrile initiated by copper (II) nitrate in presence or absence of triphenylphosphine
Authors: Bartoň J. , Vlčková J. , Ondrejovič G. , Gažo J.
Published: April 2003

The bulk polymerization of acrylonitrile (AN) initiated by copper (II) nitrate, Cu(II), in the absence of light has been studied. The rate of the AN polymerization may be expressed in the Cu(II) concentration range from 5 × 10−4 to 1 × 10−1 mole 1.−1 by the equation, Rp = k5[Cu(II)]0.68, where k5 = KAN[AN]/(1 + KAN[AN]). From the spectrophotometric measurements the values of 0.70 l./mole and 0.08 l, mole were obtained for the equilibrium constant at 20 and 60°C, respectively, KAN = [C]/[AN]‐[Cu(II)], corresponding to the formation of the complex C from acrylonitrile and copper (II) nitrate. An addition of triphenylphosphine (C6H5)3P into the polymerization system reduces Rp, and no polymerization takes place at all provided [(C6H5)3P]/[Cu‐(II)] ≧ 5. The retardation effect of (C6H5)3P on the polymerization of AN initiated by Cu(II) is attributed to a competitive reaction of Cu(II) with (C6H5)3P in which Cu(II) is reduced and the product of this reduction CuNO3·2(C6H5)3P is inactive with respect to the polymerization of AN.
Reactions of models of the growth center during anionic polymerization of methacrylate esters
Authors: Lochmann L. , Rodová M. , Petránek J. , Lím D.
Published: April 2003

Reactions of α‐lithioisobutyric acid esters were studied as models of partial reaction taking place during anionic polymerization of methacrylate esters. The rates of selfcondensation reactions and condensations with nonmetalated esters were determined for these models. In both cases ketoesters were the final products. Besides esters of α,α,α′‐trimethylglutaric acid expected according to Michael's reaction scheme the addition of methacrylate esters to α‐lithio esters also yielded oligomeric compounds due to repeated addition of methacrylate esters. The α‐lithio oligomers of methacrylate esters underwent cyclization condensation which gave rise to esters of substituted cyclohexanonedicarboxylic acids. The alkali metal alkoxides slowed down all the condensation reactions of α‐lithio esters investigated here. Such effect of alkoxides also appeared in the cyclization condensation of compounds formed by repeated addition of methacrylate esters, because in the presence of alkoxides the reaction mixture contained a higher amount of higher molecular weight compounds than in a system without alkoxide. The effect of alkoxides observed here is in accordance with the view that the cyclization condensation is one of the termination reactions of the anionic polymerization of methacrylate esters.
Thermal degradation of chlorinated rubber: Evidence for an alternative cyclic structure for chlorinated rubber
Authors: Dodson B. , McNeill I. C.
Published: April 2003

The thermal degradation under vacuum or in nitrogen of commercial chlorinated rubber (ICI Alloprene, 64.5 wt.‐% chlorine) was studied by isothermal thermogravimetry and by simultaneous TG/TVA with programmed heating by using a Cahn RG thermobalance built into a thermal volatilization analysis (TVA) system. Analysis of volatile products was performed by titration and by spectroscopic methods. The only major degradation product is hydrogen chloride; five‐sevenths of the total available hydrogen chloride is lost with great ease, and complete dehydrochlorination is very much easier than in poly(vinylidene chloride). Conjugation develops early in the degradation, but the minor products methane, ethylene, and hydrogen are observed in the later stages of reaction. These features cannot be reconciled with the previously proposed cyclic structure for chlorinated rubber, and an alternative structure which accounts well for the degradation behavior is suggested.
Syntheses and reactions of porphyrin and metalloporphyrin polymers
Authors: Kamogawa Hiroyoshi
Published: April 2003

Various porphyrin functions such as protoporphyrin IX and chlorin a as well as metalloporphyrin functions such as Mg(II)– and Cu(II)–chlorophyllin a and Fe(III)– and Co(II)–protoporphyrin IX were incorporated into vinyl polymers by preparation and polymerization of their p‐vinylbenzyl esters. The porphyrin function was also incorporated by reaction of poly‐p‐chloromethylstyrene with porphyrins or metalloporphyrins or by the reaction of p‐aminostyrene polymers with chlorophyll b through Schiff‐base formation. Mg(II)–porphyrin polymers were found to be remarkably effective as catalysts in photoredox systems; porphyrin polymers without central metal atoms were also effective to a lesser extent.
Polymerization of vinyloxyaluminum and formation of syndiotactic poly(vinyl alcohol)
Authors: Nozakura Shun‐Ichi , Kida Sueo
Published: April 2003

The polymerization of diisobutylvinyloxyaluminum, CH2CHOAl(i‐Bu)2, and diethylvinyloxyaluminum, CH2CHOAlEt2, did not take place in the presence of typical radical or cationic initiators. The polymerization was realized at 60°C by the addition of tetrahydrofuran (THF) or tetrahydropyran, no conventional initiator being required. Diethyl ether, glyme, and dioxane were not effective on the polymerization. At Dry Ice–acetone temperature, polymerization did not take place, even in the presence of tetrahydrofuran, but did take place in the presence of both THF and SnCl4. The role of cyclic ethers in the polymerization was studied. Polymers were converted into poly(vinyl alcohol) (PVA) by solvolysis. All the resulting PVA was syndiotactic; particularly polymers obtained at −78°C showed syndiotactivity of 89%, which is the highest value ever reported.
Preparation of poly‐p‐benzenesulfonamide
Authors: Kersting R. James , Hulse George E.
Published: April 2003

The poly‐p‐benzenesulfonamide (PBS) structure has been prepared by the transamidation of N1,N1‐dimethylsufanilamide hydrochloride in a melt reaction at 180°C. The polymeric nature of the product is exhibited by brittle film formation and a glass transition temperature of 180–190°C. Infrared and NMR spectroscopy are consistent with the proposed structure. The number‐average degree of polymerization was measured by NMR. The maximum degree of polymerization was 14. Failure to obtain an optimum molecular weight did not appear to be due to monomer purity. Increasing the reaction temperature from 180 to 220°C led to side reactions giving insoluble and infusible product. PBS underwent thermal decomposition near 310°C. The decomposition temperature is independent of molecular weight.
Stereoregularity and polymerization mechanism of polymethacrylonitriles determined by 13C‐NMR spectroscopy
Authors: Matsuzaki Kei , Kanai Taiichi , Matsumoto Susumu
Published: April 2003

Carbon‐13 nuclear magnetic resonance (13C‐NMR) spectra of polymethacrylonitriles prepared under various conditions were measured. In acetone solution, the α‐methyl carbon absorptions were split into triads and partially into pentads, and the methylene carbon absorptions into tetrads. In trifluoroacetic acid solution, the α‐methyl carbon absorptions were split into pentads and the cyano carbon absorptions into triads. The triad, tetrad, and pentad tacticities determined from 13C‐NMR spectra were compared with dyad tacticities determined from proton NMR spectra. The stereoregularity of the polymers which are γ‐ray‐initiated in liquid phase at temperatures near melting point (−35.8°C) and in the solid state differs from that of the polymers radically initiated at −20 to 80°C. The stereoregularity and the conversion suggest the existence of an ionic mechanism in the polymerization at low temperatures.
NMR study of poly‐p‐isopropyl‐α‐methylstyrene
Authors: Leonard J. , Malhotra S. L.
Published: April 2003

220 MHz NMR spectra of sample of poly‐p‐isopropyl‐α‐methylstyrene prepared through anionic (A) and cationic (B) polymerizations are studied. Peaks at τ values of 9.07, 9.41, and 9.71 are assigned to isotactic (i), heterotactic (h), and syndiotactic (s) α‐methyl triads, respectively. From the α‐methyl triads and the β‐proton tetrads it is found that polymer A deviates little from Bernoullian statistics and that first‐order Markov configurational statistics applies to polymer B. Isopropyl methine and methyl proton resonances are also analyzed in terms of the configurational statistics of the polymer. Resonances of the phenyl protons are assigned with increasing field to s, h, i meta and ortho protons.
Synthesis of polymers by use of divalent metal salts of monohydroxyethyl phthalate: Metal‐containing isocyanurate‐type crosslinked polyurethanes
Authors: Matsuda Hideaki
Published: April 2003

Divalent metal salts (I) of monohydroxyethyl phthalate have catalytic activity for polymerization of isocyanate groups. The synthesis of novel metal‐containing isocyanurate‐type crosslinked polyurethanes were investigated by the crosslinking reaction of I in DMF with diisocyanates or urethane prepolymers, that is, diisocyanate adducts of polyethylene glycol. 2,4‐Toluene diisocyanate and diphenylmethane diisocyanate were used as diisocyanates, and DMF was the solvent. The crosslinking reactions were followed by determining the gelation time. Gelation time decreased with increasing temperature. The Ca salt was more effective than the Mg salt in the crosslinking reaction. The yields of resulting metal‐containing three‐dimensional polymers decreased with increasing metal content in the feed. The Ca salt was more easily introduced into the network polymers than the Mg salt was. Decomposition temperatures decreased on introducing metals into the network polymers. Some physical properties of the metal‐containing network polymers are also discussed.
Copolymerization of styrene. V. Copolymerization with α‐cyanocinnamamide
Authors: Liebersohn Aharon , Kohn David H.
Published: April 2003

Copolymers of styrene with α‐cyanocinnamamide were prepared by free radical initiation in bulk and in DMF solution and also by thermal initiation in bulk. The copolymerization parameters were determined by the conventional scheme of copolymerization and by an improved scheme taking into account the penultimate unit. Different values of the copolymerization parameters were obtained at the above mentioned different polymerization conditions, indicating the existence of a solvent effect. The influence of the comonomer on some of the basic properties, like intrinsic viscosity, solubility, melting range, and glass transition temperature and on some mechanical and behavior properties of the copolymers was studied in comparison with homopolystyrene.
Solid‐state polymerization of a cyclic diacetylene
Authors: Baughman R. H. , Yee K. C.
Published: April 2003

Large polymeric single crystals of a unique ring‐bridged polymer have been produced by the solid‐state polymerization of a cyclic diacetylene (o,o′‐diacetylenyldiphenyl glutarate). These crystals are of high thermal stability, metallic in appearance with an asbestos‐like texture, infusible, and insoluble. Single‐crystal x‐ray diffraction investigation indicates that the polymer is monoclinic (probable space group C2/c or Cc) with a unit cell containing four monomer units of dimensions α = 20.8 Å, b = 8.0 Å, c = 9.7 Å, and β = 106°. Infrared spectra eliminate the previously suggested possibility that the solid‐state reactivity of the above monomer corresponds to either reaction of the carbonyl function with the acetylenic bond or the cleavage of the ester linkage. Diffraction, dichroism, and Raman spectral studies indicate instead that the reaction proceeds by 1,4‐addition polymerization at the diacetylene group to produce a trans–trans polymer of structure
magnified image
where the curved lines represent the di‐(o‐phenyl)‐glutarate linkages which are on opposite sides of the chain for adjacent monomer units.
Effect of nonelectrostatic interactions on the macromolecular behavior of polyelectrolytes. I. Potentiometric titrations of PLL in water and aqueous–organic mixtures
Authors: Fenyo Jean‐Claude , Beaumais Jacques , Selegny Eric
Published: April 2003

The potentiometric and viscosity behavior of salt‐free solutions of the polycondensate between L‐lysine and 1,3‐benzenedisulfonyl chloride (PLL) and related polyelectrolytes, have been investigated in water and in aqueous–organic mixtures (acetone–water). The effects of counterions and solvent on the pH‐induced conformational transition is related to hydrophobic interactions. The transition from a compact state to a more extended one shifts towards high values of neutralization with increasing length of N‐tetraalkylammonium counterions. Moreover, the above transition gradually disappears as the percentage of acetone in the mixture is increased, which is interpreted as reflecting the breakdown of the compact structure due to hydrophobic interactions stabilized by bulky counterions. A linear decrease in the free energy variation ΔGt° is observed with increasing percentage of acetone up to about 40% of acetone, and a value of 1200 cal/unit is obtained for PLL in water, which is a reasonable value compared to other data for hydrophobic polyelectrolytes.
Effect of nonelectrostatic interactions on the macromolecular behavior of polyelectrolyes. II. Influence of urea and dyes on the viscometric and optical behavior of PLL
Authors: Muller Guy , Fenyo Jean‐Claude , Beaumais Jacques , Selegny Eric
Published: April 2003

The effect of urea and of dyes on the viscometric behavior of aqueous solutions of PLL has been investigated. The compact structure, which is characteristic of PLL in pure water, is found to disappear progressively as the amount of urea is increased. This is interpreted as due to the destruction in such media of nonelectrostatic interactions responsible for the stabilization of the compact structure of PLL in pure water. In 8M urea, the macromolecular behavior of PLL during the ionization is dependent only on the repulsive interactions between the charged groups. The extension of PLL is then practically independent of the nature of counterions, contrary to what was observed in pure water. In the presence of dye (acridine orange), the compact form of PLL is stabilized, and the dye is found to bind for the two structures of PLL. The analogy between the behavior of Bu4N+ and that of dye is in agreement with the fact the Bu4N+ leads to a stabilization of the compact structure by way of specific interactions between N‐tetraalkylammonium counterions and the PLL chain through the structure of water. The hydrodynamic behavior of PLL is in good agreement with data obtained from potentiometric and optical activity measurements.
Melting behavior of highly stretched isotactic polypropylene film
Authors: Tanaka Hiroshi , Takagi Nobuyuki , Okajima Saburo
Published: April 2003

Isotactic polypropylene film was stretched in poly(ethylene glycol) at 140°C and its melting behavior was investigated by using a differential scanning calorimeter (DSC‐1B). The shape of the melting curve depends largely on the stretching ratio, v. A sample stretched to moderate extension (1 < v < 3.5–4) has only a single melting peak (163°C) in the thermogram. When the sample is stretched beyond v = 3.5–4, the thermogram becomes more and more complex with increase of v, and some peaks appear when stretched to 10 < v < 13. The lowest peak which is considered to be the melting peak of the intermolecular crystals produced by the unfolding of chain molecules in the lamellae develops gradually with increase of v. In the thermogram for v = 18 the lowest temperature peak is most pronounced, in contrast to the highest temperature peak which decreases markedly in intensity. The phenomenon shows that large amounts of lamellar crystals are converted to intermolecular crystals in this region. On further stretching (v > 20) a very sharp high temperature peak appears, whose half‐width is about 1°C. Qualitatively similar results were obtained for the samples stretched in poly(ethylene glycol) at 150°C and in air at 140 and 150°C.
Effect of oxygen on the polymerization of vinyl chloride. II. Polymer properties
Authors: Garton A. , George M. H.
Published: April 2003

The bulk and suspension polymerizations of vinyl chloride have been carried out in the presence of small known amounts of added oxygen at 54°C in the presence of peroxide initiators. The concentrations of oxygen were in the range 0–1240 ppm for 1‐gal bulk polymerization systems and 0–400 ppm for 15‐gal suspension polymerization systems. The thermal stabilities of the polymers prepared in the presence of oxygen were lower than those prepared under corresponding oxygen‐free conditions. The average molecular weights of bulk polymers isolated at relatively low conversions were reduced in the presence of oxygen, and the infrared spectra of the polymers were altered. The significance of the decreased thermal stabilities of the polymers prepared in the presence of oxygen is discussed briefly in relation to the possible sites of initiation of dehydrochlorination.
Vinylhydroquinone. III. Copolymerization of vinylhydroquinone and vinyl monomers by tri‐n‐butylborane
Authors: Iwabuchi S. , Kojima K. , Nakahira T. , Ueda M. , Kobayashi M. , Iwakura M.
Published: April 2003

The copolymerization of vinylhydroquinone (VHQ) and vinyl monomers, e.g., methyl methacrylate (MMA), 4‐vinyl‐pyridine (4VP), acrylamide (AA), and vinyl acetate (VAc), by tri‐n‐butylborane (TBB) was investigated in cyclohexanone at 30°C under nitrogen. VHQ is assumed to copolymerize with MMA, 4VP, and AA by vinyl polymerization. The following monomer reactivity ratios were obtained (VHQ = M2): for MMA/VHQ/TBB, r1 = 0.62, r2 = 0.17; for 4VP/VHQ/TBB, r1 = 0.57, r2 = 0.05; for AA/VHQ/TBB, r1 = 0.35, r2 = 0.08. The Q and e values of VHQ were estimated on the basis of these reactivity ratios as Q = 1.4 and e = −;1.1, which are similar to those of styrene. This suggests that VHQ behaves like styrene rather than as an inhibitor in the TBB‐initiated copolymerization. No homopolymerization was observed either under nitrogen or in the presence of oxygen. The reaction mechanism is discussed.
Ester phenyl‐as‐triazine and ester phenylquinoxaline polymers
Authors: Hergenrother Paul M.
Published: April 2003

A series of new high molecular weight soluble ester phenyl‐as‐triazine and ester phenyl‐quinoxaline polymers were prepared by solution cyclopolycondensation of oxalamidrazone or 3,3′‐diaminobenzidine, respectively, with various bis(benzilyl)esters. Ester groups are incorporated within the backbone of the polymer chain and also as pendant groups on the heterocyclic ring. By TGA in air, initial weight losses for the all‐aromatic polyester phenyl‐as‐triazines and polyester phenylquinoxalines began at ca. 350 and 400°C, respectively. Films of ester phenyl‐as‐triazine and ester phenylquinoxaline polymers exhibited good thermo‐oxidative stability after aging in circulating air at 232 and 288°C, respectively. Two phenylquinoxaline model compounds were also prepared.