bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoaddition of maleic anhydride to unsaturated polymers in homogeneous solution, solid polymer–solution, and solid polymer–vapor systems
Authors: Tazuke Shigeo , Kimura Hitoshi
Published: April 2003

Photoreactions of maleic anhydride (MAH) with unsaturated olefinic polymers such as 1,2‐polybutadiene, 1,4‐polybutadiene, block copolymer of styrene and butadiene, polystyrene, poly(styrene‐co‐isoprene), and poly(styrene‐alt‐methyl methacrylate) were investigated in air. When the polymers have olefinic unsaturation, the addition of MAH to the polymers in homogeneous solutions proceeded efficiently by a chain mechanism, and the quantum yield of the photoaddition of MAH was greater than unity under irradiation at λ > 310 nm. From the effects of solvent and photosensitizer, a radical chain mechanism involving crosslinking of the polymers by MAH molecules was suggested. Together with the spectroscopic results, the reaction mechanism was discussed. The photoaddition reaction was then applied to the surface photomodification of polymer films. Photoreactions were conducted at the interphase between solid polymer and acetone solution of MAH and also at the interphase between solid polymer and gaseous MAH. Irradiation by a 300‐W high‐pressure mercury lamp could bring about considerable modification of the surface properties of the polymers, which then show improved wettability and dyeability. From the oxygen permeation experiments, the present interfacial phototreatment was shown to provide a double‐layered polymer film in which one side of the film is polar and hydrophilic while the other side is nonpolar and hydrophobic.
Synthesis of polyamides from active N,N′‐diacylbis‐2‐benzothiazolones and diamines under mild conditions
Authors: Ueda Mitsuru , Sato Akira , Imai Yoshio
Published: April 2003

The aminolysis of N‐benzoyl‐2‐benzothiazolone was studied in model systems and was found to give excellent yields of N‐substituted benzamides at room temperature. Solution polycondensation of new bisamides, N,N′‐adipoylbis‐2‐benzothiazolone and N,N′‐isophthaloylbis‐2‐benzothiazolone, proceeded fairly slowly with both aromatic and aliphatic diamines at room temperature to yield polyamides having inherent viscosities up to 1.5. Hexamethylphosphoramide was the best polycondensation medium among some polar aprotic solvents for the formation of high molecular weight polyamides. The high reactivity of the N‐acyl‐2‐benzothiazolones was discussed in relation to excellent leaving nature and intramolecular general base catalysis of the benzothiazolone moiety.
Preparation and properties of polyamides and polyimides containing phenoxathiin units
Authors: Ueda Mitsuru , Aizawa Tatsuo , Imai Yoshio
Published: April 2003

Novel polyimides and polyimides having phenoxathiin units have been prepared. Polyamides with inherent viscosities in the range of 0.5–2.9 were readily prepared by the polycondensations of phenoxathiin diamines with aromatic diacyl chlorides and of aromatic diamines with new phenoxathiin diacyl chlorides. The polyimides were synthesized from phenoxathiin diamines and pyromellitic dianhydride by using a two‐step procedure. The polyamic acids which formed in the first step had inherent viscosities ranging from 1.0 to 1.6, and they were converted to the polyimides by thermal cyclodehydration. Some of the phenoxanthiin‐containing polyamides were highly soluble in polar amide solvents and dimethyl sulfoxide. A series of novel polymers containing phenoxathiin units were much more thermostable than the corresponding polymers having open‐chain diphenyl ether linkages.
Application of ESCA to polymer chemistry. XVI. Electron mean free paths as a function of kinetic energy in polymeric films determined by means of ESCA
Authors: Clark D. T. , Thomas H. R.
Published: April 2003

Electron mean free paths as a function of kinetic energy have been measured by the substrate overlayer technique for in situ‐polymerized films of poly(p‐xylylene) and the monochloro‐ and monobromo‐substituted derivatives. The results are compared with previous estimates of mean free paths available in the literature for organic materials. Comparison is also drawn with corresponding experimental data for typical metals and semiconductors, and it is shown that organic polymers fit into a consistent picture which may be rationalized on the basis of existing theory. For electrons of kinetic energy ∼969 eV, ∼1170 eV, 1202 eV, and 1403 eV, mean free paths of ∼14 Å, ∼22 Å, ∼23 Å, and ∼29 Å, respectively, are obtained for the poly(p‐xylylene) polymer films studied in this work.
Radical polymerization of methyl methacrylate in the presence of isotactic poly(methyl metacrylate). VII. Determination of the rate constants for template polymerization
Authors: Gons J. , Vorenkamp E. J. , Challa G.
Published: April 2003

The separate rate constants kp and kt for propagation and termination of radical template polymerization of methyl methacrylate along isotactic poly(methyl methacrylate) as a polymer template have been determined. The polymerizations were carried out in the strongly complexing solvent dimethylformamide at 5°C. For the evaluation of k/kt from stationary kinetic experiments, the rates of initiation were determined by employing a scavenger method. The nonstationary experiments yielding kp/kt were performed by means of the rotating sector technique. As the template rate effects increased with decreasing initiator concentration, the rotating sector curves were corrected for variation in light intensity. It appeared that the radical lifetime increases from 8.4 sec for normal or blank polymerization to 64 sec for template polymerization. The calculated values of kp are 26.6 and 5.9 l./mole‐sec and of kt 140 × 104 and 1.7 × 104 l./mole‐sec for blank and template polymerization, respectively. The changes in kp and kt, due to the presence of template polymer, are explained in terms of an extra loss of activation entropy in the stereoselective propagation step and a strong hindrance of segmental diffusion for the termination reaction of the chains growing along the polymer template.
Dielectric studies of photodegradation and photooxidation of polystyrene
Authors: Weir N. A.
Published: April 2003

The effects of vacuum photolysis at 254 nm and the short‐(λ = 254 nm) and long‐wave (λ > 300 nm) photooxidations on the dielectric constants (ϵ′) and dielectric losses (ϵ″) of polystyrene have been investigated at 25 ± 1°C. Dielectric constants generally increase on photodegradation, but more pronounced increases occur in the low‐frequency region on vacuum photolysis. It is suggested that such increases are associated with Maxwell‐Wagner‐Sillars polarization. Increases in dielectric losses are observed in three main frequency regions: around 102 Hz, 104 Hz, and at 3 × 106 Hz. The lowest frequency loss which occurs in both the vacuum‐irradiated and in the photooxidized samples is attributed to a combination of the effects of interfacial polarization and of the increased direct‐current conductivity of the polymer which occurs as a result of these reactions. The 104 Hz dispersion associated only with photooxidation is related to the presence of small, volatile, polar oxidation products, like ketones. The loss peak overlaps the intrinsic γ‐relaxation of polystyrene, and it appears that the motions of small molecules, or of relaxing dipoles in these, are coupled to the phenyl group rotational vibrations. The high‐frequency losses (3 × 106 Hz) are ascribed to orientation polarization of carbonyl dipoles attached to chain ends, these compounds being produced as a result of hydroperoxide decompositions. A good correlation between the carbonyl dipole relaxation strength and carbonyl concentration is observed. It would appear that relaxation strength measurements could provide quantitative kinetic information for polystyrene oxidation.
Peroxide‐Initiated crosslinking of styrene‐grafted polymers and copolymers of butadiene
Authors: Gasperowicz Aleksandra , Łaskawski Włodzimierz
Published: April 2003

Low molecular weight polymers and copolymers of butadiene were grafted with styrene. The graft products were then crosslinked by using dicumyl peroxide as initiator. The optimum peroxide concentration was established (5 phr). Infrared analysis showed that the reactivity of 1,2‐vinyl and that of 1,4‐trans double bonds in styrene‐grafted polybutadiene is similar. Crosslinking of the graft product seems to involve a radical‐chain polymerization of double bonds in the polymer. The reaction rate is proportional to the square root of peroxide concentration and to the concentration of polymer double bonds. Activation energy, reaction heat, reaction order, and crosslinking efficiency were also determined from DSC measurements. No relation was found between the activation energy of crosslinking and the molecular weight of backbone polymer or density of grafting. Crosslinking efficiency was to 25–50 crosslinks per molecule of decomposed peroxide. The crosslinking efficiency for grafted butadiene–styrene copolymers is somewhat lower than that for grafted polybutadienes. From thermogravimetric measurements it was found that the crosslinked grafted polymers show lower resistance to thermal degradation than ungrafted polymers.
Dielectric properties of moist cellulose
Authors: Boutros S. , Hanna A. A.
Published: April 2003

The dielectric constant ϵ′ and the dielectric loss ϵ″ for cellulose fiber were measured over a frequency band 0.2 to 10 Mc/sec and a temperature range from −20 to 80°C. Also, the variation of the dielectric behavior with relative humidity was measured at 25°C. From these data, both the specific resistivity Rs and the dissociation energy U0 were calculated. The results showed that the dielectric constant increased with frequency and temperature. This may be due to the increase in the rotation and the polarization of the flexible part in the fiber. The variation of the dielectric loss with temperature showed a maximum absorption corresponding to the β‐relaxation. For the moist fiber, it is found that as the relative humidity increases, the dielectric constant and the dielectric loss increase. This increase may be due to the presence of polar water molecules, to the freeing of the polar groups, and to the freeing of the ions in the fiber molecule as well as to the increase in the number of OH− and H+ ions resulting from the ionization of water. A relation between the dielectric constant and resistivity at different humidities is represented graphically. From this relation, it is found that the dissociation energy is equal to 0.318 × 10−12 and 5.46 × 10−12 erg below and above 52% RH, respectively.
Asymmetric induction copolymerization of optically active l‐menthyl vinyl ether with styrene and N‐phenylmaleimide
Authors: Kurokawa Masahiro , Doiuchi Tohru , Yamaguchi Hidemasa , Minoura Yuji
Published: April 2003

The copolymerizations of l‐menthyl vinyl ether (l‐MVE) with styrene (St) and N‐phenylmaleimide (N‐PMI) as comonomers were carried out in benzene with azobisisobutyronitrile (AIBN) as an initiator to give optically active copolymers. After the removal of the optically active menthyl group by use of hydrogen bromide gas, the ether‐cloven l‐MVE‐N‐PMI copolymer (VA‐N‐PMI) was still optically active. On the other hand, the optical activity of l‐MVE‐St copolymer disappeared after ether cleavage. It is thought that asymmetric induction took place in the polymer main chains. The optical rotatory dispersion and circular dichroism of the original and ether‐cloven copolymers were measured in order to confirm the asymmetric induction.
Cationic polymerization with boron halides. V. Synthesis of poly(isobutylene‐b‐styrene) and poly(styrene‐b‐isobutylene)
Authors: Kennedy J. P. , Feinberg S. C. , Huang S. Y.
Published: April 2003

Block copolymers of isobutylene and styrene, PIB‐b‐PSt and PSt‐b‐PIB, have been prepared by a two‐step synthesis involving (1) preparation of terminally chlorinated (telechelic) polyisobutylene or polystyrene “prepolymers” by using the H2O/BCl3 initiator system and (2) blocking from these telechelic prepolymers a second polymer segment by using an alkyaluminum, e.g., Et2AlCl coinitiator. The telechelic polyisobutylene and polystyrene contain tertiary and benzylic chlorine termini, respectively. Block copolymer characterization included detailed selective solvent extraction procedures, coupled with GPC determinations, PMR, solubility, and intrinsic viscosity studies. The synthesis of PIB‐b‐PSt and PSt‐b‐PIB provides direct chemical evidence for the presence and position of active chlorine termini in BCl3‐coinitiated olefin polymerizations.
Distribution of polymer deposition in plasma polymerization. II. Effect of reactor design
Authors: Yasuda H. , Hirotsu Toshihiro
Published: April 2003

The effects of relative positions of the monomer inlet and the r.f. coil, and of the inlet and outlet, on the distribution of polymer deposition in plasma polymerization of ethylene were investigated using an electrodeless glow discharge by a 13.5‐MHz radiofrequency source. The diffusional transport of active species created under the r.f. coil, diffusional transport of polymer forming species, and flow of gas in the system are important factors that determine the distributions of polymer deposition observed in plasma polymerization of ethylene. The mechanisms of polymer deposition are discussed in conjunction with postulated plasma polymerization mechanisms.
Reactivity of halophenol and formation of phenoxo–copper(II) complex in basic copper‐catalyzed halogen displacement polymerization
Authors: Tsuruya Shigeru , Okumoto Kazutomo , Yoshimatsu Atkashi
Published: April 2003

The halogen displacement polymerization of 2,4,6‐trihalophenol with heterogeneous basic copper(II) complex is described. The corresponding poly(dihalophenylene oxides) have been obtained from 2,4,6‐trichloro‐, 2,4,6‐tribromo‐, and 2,4,6‐triiodophenol with the present catalytic system. In the halophenols used, the order of reactivity was as follows; 2,4,6‐trichloro‐ < 2,4,6‐tribromo‐ < 2,4,6‐triiodophenol. With 2,4,6‐trichlorophenol as a monomer, the 2,4,6‐trichlorophenoxo–copper(II) complex, which had the composition Cu(OCH3)(C6H2Cl3O) and was considered to be a reaction intermediate, was isolated. The ESR spectrum of this complex at room temperature showed a sharp peak considered to be free organic radical, in addition to the broad one based on copper(II) ion. Poly(dichlorophenylene oxide) was obtained by thermal decomposition of the phenoxo–copper(II) complex. It was concluded that the formation and decomposition of the phenoxo–copper(II) complex were intermediate steps of halogen displacement polymerization of 2,4,6‐trihalogenophenol with heterogeneous basic copper(II) catalyst.
Vinyl polymerization by metal complexes. XXV. Photopolymerization of vinyl monomers by porphyrin–iron(III) complex
Authors: Inaki Y. , Takahashi M. , Kameo Y. , Takemoto K.
Published: April 2003

Photopolymerization of methyl methacrylate was studied in the presence of the system of the tetraphenylporphine–iron(III) complex, free amine, and carbon tetrachloride at 0°C in methanol solution. It was found that the activity of the complex for polymerization does not depend upon the structure of the free amines added. The effect of the polymeric amines on the polymerization was also examined. The photochemical reaction process among the iron(III) complex, amine, and carbon tetrachloride was followed also under similar conditions by ultraviolet and visible spectroscopy. The scheme for the initiation species presented is supported by the results on the posteffect of the photopolymerization.
Preparation of polymers containing the 1,3,4‐oxadiazoline‐5‐thione structure and their application to the activation of N‐protected α‐amino acids
Authors: Fukuda Hiroyuki , Endo Takeshi , Suyama Masayoshi , Okawara Makoto
Published: April 2003

Two new monomers with pendent 1,3,4‐oxadiazoline‐5‐thione structures were prepared. Homopolymerization of 2‐isopropenyl‐1,3,4‐oxadiazoline‐5‐thione (V) and copolymerization with styrene (M1)(r1 = 0.02, r2 = 1.56, Q = 4.12, e = 1.06) were examined. Further, 2‐(4‐methacryloylaminophenyl)‐1,3,4‐oxadiazoline‐5‐thione (VIII) having a phenylcarbamoyl group between the isopropenyl and 1,3,4‐oxadiazoline‐5‐thione ring as a spacer was also synthesized and polymerized. The resultant polymers were allowed to react with N‐protected α‐amino acids such as Z‐AlaOH, Z‐LeuOH and Z‐PheOH by the DCC method. The polymers containing amino acids thus obtained were reacted with ethyl glycinate to give the corresponding dipeptides in excellent yields without racemization.
Synthesis of vinyl graft copolymers of poly(hexamethylene adipamide) and poly(m‐phenylene isophthalamide)
Authors: Kashani H. Akhavan , Barrie J. A. , George M. H.
Published: April 2003

Nylon 66 [poly(hexamethylene adipamide)] and Nomex [poly(m‐phenylene isophthalamide)] were metalated by using solutions of sodium in liquid ammonia. Metalation of the Nomex polymer was also carried out by using sodium naphthalene in tetrahydrofuran. The metalated polymers were then reacted with acrylonitrile monomer to yield the corresponding anionic graft copolymers. The heterogeneous nature of these reactions is discussed in relation to the structure of the graft copolymers.
15N‐NMR spectroscopy. III. Neighboring residue effects in sequence polymers containing glycylglycine units
Authors: Kricheldorf Hans. R. , Hull William E.
Published: April 2003

The tripeptides Phe‐Gly‐Gly, β‐Ala‐Gly‐Gly, and ϵ‐Aca‐Gly‐Gly as well as the peptide derivatives δ‐isothiocyanatovaleroyl‐Gly‐Gly and ϵ‐isothiocyanatocaproyl‐Gly‐Gly were synthesized by using known methods so that the peptide nitrogen between the two glycyl residues was isotopically enriched in 15N to a level of 0.8–0.9%. These monomer units were then used to produce the sequence polymers (Phe‐Gly‐Gly)n, (β‐Ala‐Gly‐Gly)n, (δ‐Ava‐Gly‐Gly)n, and (ϵ‐Aca‐Gly‐Gly)n. The 18.24 MHz 15N‐NMR spectra of the oligo‐ and polypeptides were obtained by using trifluoroacetic acid as solvent, since the solutions have relatively low viscosity and exhibit a strong negative nuclear Overhauser enhancement of the 15N signals. For comparison, 15N‐NMR spectra of the homopolymers (Gly)n, (β‐Ala)n, (γ‐Abu)n, (δ‐Ava)n, and (ϵ‐Aca)n were also recorded. The 15N signals from the ω‐aminoacyl residues in the sequence polymers appear up to 11 ppm upfield of the signals observed for the homopolyamides. The 15N signals from the two glycyl residues are separated by 3–7 ppm. Comparison with the 13C‐NMR spectra of the same polymers indicates that 15N‐NMR is better suited for the characterization and sequence analysis of these types of polymers.
Microheterogeneity in crosslinked polysiloxanes
Authors: Katz D. , Zewi I. G.
Published: April 2003

Previously reported studies on crosslinked castable poly(dimethylsiloxanes) have been extended. A series of dimethylsiloxane difumarates were copolymerized with styrene, and some of their rheological properties were determined. Investigation of these and previously prepared polymers has shown that segregation on a microscale can take place in two‐component crosslinked systems with relatively short network chains. This may occur even if one of the components is a nonpolymeric species involved in crosslinking. Microheterogeneity was observed in systems made up of prepolymer chains of a single type, when these were short enough to expose a specific structure of the crosslinking site. It seems that microheterogeneity can be expected in crosslinked polymers when the size of the crosslinking site is significant in comparison with the network chain length and when its cohesive energy density differs considerably from that of the main network chains. Additional factors affecting microphase separation include the existence of physical interactions between chemical groups, steric positioning of interacting groups during the process of crosslinking, and physical effects of the degree of crosslinking leading to local differences in the density of the system.
Photopolymerization of methyl methacrylate with the use of iodine monobromide as photoinitiator
Authors: Ghosh Premamoy , Banerjee Harihar
Published: April 2003

Iodine monobromide easily induces photopolymerization of methyl methacrylate (MMA) at 40°C under visible light. Initiator exponent and monomer exponent values were found to be 0.5 and 2, respectively, at low initiator concentrations, while the corresponding values at high initiator concentration conditions were zero and 3. The chain transfer constant of IBr at 40°C was found to be 13.0. Kinetic and other data indicate a radical polymerization mechanism involving complexation of monomer molecules with iodine monobromide prior to radical generation, and termination is believed to take place biomolecularly at low IBr concentrations and unimolecularly, involving reaction with the initiator, at high IBr concentrations (initiator termination).
Polymerization of vinyl chloride at reduced monomer accessibility. II. Polymerization at subsaturation pressure with emulsion PVC as seed
Authors: Hjertberg Thomas , Sörvik Erling M.
Published: April 2003

Vinyl chloride was polymerized at 59–92% of saturation pressure in a water‐suspended system at 45–65°C with an emulsion poly(vinyl chloride) (PVC) latex as a seed. A water‐soluble initiator was used in various concentrations. The monomer was continuously charged as vapor from a storage vessel kept at lower temperature. Characterization included determination of molecular‐weight distribution and degree of long‐chain branching by gel permeation chromatography (GPC) and viscometry, thermal dehydrochlorination, and microscopy. The polymerization rate decreases with decreasing pressure but is reasonable even at the lowest pressure. The molecular weight decreases with decreasing pressure and increasing initiator concentration and also with increasing polymerization temperature, if the initiator concentrations are chosen to give a constant initiator radical concentration. The degree of long‐chain branching increases with increasing initiator concentration and decreasing monomer pressure but is unaffected by the polymerization temperature, if the initiator radical concentration is kept constant. The thermal stability decreases with decreasing Mn, while the degree of long‐chain branching has only a minor influence. The most important factor in the system influencing the molecular parameter is the monomer accessibility.
Supported bis(indenyl)– and bis(fluorenyl)–chromium catalysts for ethylene polymerization
Authors: Karol Frederick J. , Munn William L. , Goeke George L. , Wagner Burkhard E. , Maraschin Norma J.
Published: April 2003

Silica‐supported bis(indenyl)– and bis(fluorenyl)–chromium catalysts show good activity in ethylene polymerization. For maximum productivity with the indenyl chromium catalyst, the silica must be dried, with higher dehydration temperatures giving a significant increase in polymerization activity. Less deactivation on thermal aging of the supported bis(indenyl)–chromium catalyst allows ethylene polymerization to proceed for many hours, which provides polyethylenes of low residual chromium content. In contrast to the behavior of supported chromocene catalysts, the indenyl–and fluorenyl–chromium catalysts require a higher hydrogen/ethylene ratio to achieve a specific polymer melt index. Nevertheless, highly saturated polyethylenes are produced with these new catalysts. This result indicates that chain transfer to hydrogen remains the major chain transfer reaction. Addition of cyclopentadiene to a supported indenyl–chromium catalyst provided a catalyst with a much higher transfer response to hydrogen. This result suggests that ligand exchange occurred, producing a supported chromocene catalyst. These overall results are consistent with an active‐site model which comprises a supported divalent chromium center attached to an indenyl or fluorenyl ligand during the polymerization process. Polymerization is believed to occur by a coordinated anionic mechanism of the type previously discussed for a supported chromocene catalyst.
Copolymerization and homopolymerization reactions in systems containing electron‐donor monomer, electron‐acceptor monomer, and lewis acid
Authors: Kuran Witold , Pasynkiewicz Stanisław , Florjańczyk Zbigniew , Łyszkowska Danuta
Published: April 2003

Investigations of the copolymerization of acrylonitrile, methacrylonitrile, methyl acrylate, methyl methacrylate, acrylic acid, acryloyl chloride, methyl vinyl ketone, and acrolein with styrene, and of acrylonitrile with acenaphthylene and 1,3‐cyclopentadiene in the presence of Lewis acids as catalysts have been carried out. It was found that the free‐radical alternating copolymerization and ionic copolymerization or homopolymerization reactions can proceed in these systems. The yield of the competitive free‐radical and ionic reactions was related to the type of monomers and strength of the Lewis acid. The mechanism of the catalytic effect of Lewis acids in the reactions studied is discussed.
Nonclassical urea oligomers. I. Selective reactivity of 1‐(N‐substituted‐carbamyl)aziridine for ring‐transformation reactions and ring‐opening polymerization
Authors: Araki Takeo , Nogami Fumio , Tsukube Hiroshi , Nagata Koichi , Iyoshi Shuso
Published: April 2003

The reaction course of 1‐(N‐phenyl‐carbamyl)aziridine with NaI was found to be highly sensitive to the nature of solvent used; e.g., acetone preferentially gives 1‐phenyl‐2‐imidazolidinone, whereas dimethylformamide (DMF) gives 2‐anilino‐2‐oxazoline. Nuclear magnetic resonance (NMR) study of the solvent effect revealed the relation between the site in the aziridine compound, with which the solvents interact, and the reaction products. From the results obtained by these ring‐transformation studies, the use of diethyl sulfate, which is expected to solvate simultaneously at the carbonyl oxygen and the carbamyl–nitrogen atoms, resulted in polymerization of the monomer selectively to the oligomer of type—[CH2CH2N(CONHPh)]n—. The diethyl sulfate was shown to play dual roles as a solvating reagent and an initiator. The oligomer obtained includes relatively definite amount (one molecule per ca. four monomer units) of diethyl sulfate in the “washed” state. The absorbed diethyl sulfate can be removed by treating with aqueous NaOH solution or Amberlite‐400 column elution without altering the chemical constitution of the backbone in the polymer. Application of the polymerization procedure to several N‐alkyl substituted monomers resulted in oligomers of a similar type. The difference in the monomer reactivity depending on the nature of the substituent groups can be due mainly to steric factors.
Polymerization of allyl esters of unsaturated acids. I. Cyclopolymerization of methyl allyl maleate
Authors: Urushido Kunio , Matsumoto Akira , Oiwa Masayoshi
Published: April 2003

Radical polymerization of methyl allyl maleate is kinetically discussed in terms of cyclopolymerization using 2,2′‐azobisisobutyronitrile (AIBN) as an initiator and benzene as a solvent at 60°C. The ratios of the rate constants of the unimolecular cyclization reaction to those of the bimolecular propagation reaction of the uncyclized allyl and vinyl radicals, KA and KV, are estimated to be 9.7 and 1.35 mole/liter by fitting the kinetic equations obtained here to the dependence of the degree of cyclization on monomer concentration, respectively; the large difference between KA and KV is also discussed in detail. On the basis of these results the formation mode and the sequence distribution of the structural units of the polymer produced are discussed in detail; thus, for the polymer obtained in the bulk polymerization, about 90% of the cyclic structures can be formed via the intramolecular attack of uncyclized allyl radical on maleic double bond and the probability of succession of the cyclic structural units in diad sequence is exemplified as 0.27.
Multichain copoly(α‐amino acid). I. Multichain copoly(α‐amino acid) prepared by reaction of copoly(L‐lysine γ‐methyl‐L‐glutamate) with N‐carboxy anhydride of Nϵ‐carbobenzyloxy‐L‐lysine
Authors: Sakamoto Munenori , Kuroyanagi Yoshimitsu
Published: April 2003

Polymerization of the N‐carboxy anhydride of Nϵ‐carbobenzyloxy‐L‐lysine in the presence of multifunctional polymeric initiator, copoly(L‐lysine γ‐methyl‐L‐glutamate) was studied in N,N‐dimethylformamide containing 3% (v/v) of dimethyl sulfoxide. Multichain copoly(α‐amino acid), i.e., multi‐Nϵ‐poly(Nϵ‐carbobenzyloxy‐L‐lysine)copoly(L‐lysine γ‐methyl‐L‐glutamate), was obtained with linear poly(Nϵ‐carbobenzyloxy‐L‐lysine) as by‐product that could be removed by reprecipitation as was evidenced by gel‐permeation chromatography. The degree of polymerization of the branch polymer chains estimated by the osmometric molecular weight determination and amino acid analysis was between 20 and 60, which decreased with increasing lysine content of the polymeric initiator. The stability of α‐helical conformation of the multichain copoly(α‐amino acid) was studied in the chloroform–dichloroacetic acid system at 25°C by the ORD technique. The α‐helical conformation of poly(Nϵ‐carbobenzyloxy‐L‐lysine) branches was less stable than those of linear poly(Nϵ‐carbobenzyloxy‐L‐lysine) and the core molecular chains of the multichain copoly(α‐amino acid).
Role of monomer charge‐transfer complexes in the free‐radical copolymerization of styrene and fumarodinitrile
Authors: Karad P. , Schneider C.
Published: April 2003

The equilibrium constant of the charge‐transfer complex of styrene and fumarodinitrile was determined by ultraviolet and NMR measurements. Information about the role of the complex in the copolymerization of the two monomers could be obtained from copolymerization experiments at different monomer concentrations and temperatures. In addition, the influence of a second donor, anisole, was studied. The results show that in the copolymerization of styrene with fumarodinitrile addition of charge‐transfer complexes has to be taken into account besides the addition of the free monomers.
Relationships on the effect of water on glass transition temperature and young's modulus of nylon 6
Authors: Reimschuessel H. K.
Published: April 2003

The glass transition temperature Tg of nylon 6 decreases monotonically toward a finite value Tgl upon increase of the moisture content. The mechanism of this decrease entails the reversible replacement of intercaternary hydrogen bonds in the accessible regions of the polyamide. The limiting glass transition temperature Tgl is approached when the moisture content approaches Wl, which corresponds to the amount of water required for complete interaction with all accessible amide groups. Denoting with Tg0 the glass transition temperature of the dry polymer, the effect of water on Tg is represented by the equation, Tg = (ΔTg)0 exp{−[ln(ΔTg)0]W/τWl} + Tgl, where (ΔTg)0 = Tg0 −Tgl, and τ = W(Tgl+1)/Wl. This equation appears to be generally applicable to hydrophilic polymers, since correspondingly calculated data are also in very good agreement with experimental data for polymers such as nylon 66, poly(vinyl alcohol), and polyN‐vinylpyrrolidone. The effect of water of Young's modulus E of nylon 6 is represented by an analogous relationship, and the quantity In[(E−El)/(Tg−Tgl)] is a linear function of the moisture content.
Mechanism of transition between cellulose I and cellulose II during mercerization
Authors: Takai Mitsuo , Colvin J. Ross
Published: April 2003

It is suggested that the transformation from cellulose I to cellulose II during mercerization is the result of a progressive shift of the sheets of cellulose chains within the crystallites of a microfibril from the quarter‐staggered relation in cellulose I to complete correspondence in cellulose II. Qualitatively, the results of such a shift would be consistent with the observed increases in lateral disorder, changes in cell dimensions, swelling, changes in infrared absorption, increases in reactivity of hydroxyl groups and especially with changes in the relative intensities of meridional, x‐ray diffraction reflections of cellulose fibers. The consequences of such a shift also include variations of the dihedral angle at the glycosidic linkage to provide an opportunity for the conformational changes which have been deduced from Raman and infrared spectra. Such a shift may take place in the transformation of native celluloses with antiparallel structure as well as those with parallel polarity. It is consistent with and is able to explain examples of “memory” of previous treatment in cellulose samples.
Selective initiation of nonconjugated dienes containing electron donor–electron acceptor systems. II. Polymerization studies of vinyl ether–β‐nitrostyrenes
Authors: Schweitert James W. , Butler George B.
Published: April 2003

The monomer series, o‐, m‐, and p‐(2‐vinyloxyethoxy)‐β‐nitrostyrenes, was studied. All three monomers were selectively polymerized through the electron‐donating vinyloxy group via cationic initiation. The linear polymers from the meta and para isomers containing the electron‐accepting nitrovinyl group were readily crosslinked via anionic initiation. The polymer derived from the ortho isomer was not crosslinked by this mechanism, an observation in accord with results previously reported from these laboratories in which it was shown that all o‐substituted‐β‐nitrostyrenes having ortho substituents larger than fluorine exhibited a sterically inhibited propagation step. The meta and para isomers of this series were selectively polymerized through the electron‐accepting nitrovinyl group via anionic initiation. Because of the fact that the resulting polymers were soluble only in highly polar solvents, subsequent crosslinking of these polymers via cationic initiation could not be accomplished. However, these polymers showed strong tendencies to undergo crosslinking upon long exposure to air. Because of the sterically induced ortho effect referred to above, no significant polymerization occurred in the case of the ortho isomer of this series via anionic initiation. However, it was shown in this case that initiation via the anion was rapid, and that the slow step was propagation.
High‐pressure polymerization of vinyl chloride
Authors: Ogo Yoshiaki , Yoshikawa Michio , Ohtani Satoshi , Imoto Tatsuya
Published: April 2003

The radical polymerization of vinyl chloride was investigated at 60°C under high pressure up to 5000 bar in benzaldehyde, benzonitrile, toluene, heptane, cyclohexane, and dioxane as solvent. In benzaldehyde and benzonitrile, the polymerizations were depressed by increased pressure. This unusual behavior was explained by the solvent participation and the effect of pressure on the propagating radicals. The crystallinities of polymer obtained in all solvents decreased with increasing pressure, as judged by the absorbance ratio of the infrared spectra. However the effects of pressure on the absorbance ratio of the polymer obtained in benzaldehyde and benzonitrile were not identical with those in the other solvents. These facts also suggest that both solvents play a special role for the solvent participation in the propagating step.
Some electrical properties of wood pulp
Authors: Boutros S. , Hanna A. A.
Published: April 2003

The variation with temperature and frequency of the dielectric constant ε′ and the dielectric loss ε″ for sheet wood pulp and ground wood pulp were measured. Also, the effect of the relative humidity on the dielectric behavior was measured for the ground sample at 25°C. For the dry ground wood pulp, the dielectric constant is larger than that for the dry sheet sample. This may be a result of the increase in the surface area, of the decrease in the size of crystals and/or of the decrease in the degree of crystallinity on grinding of the sheet sample. The variation of ε″ with frequency passes through a maximum. From the shift of this maximum with temperature, it is found that the apparent activation energy ΔH for this relaxation is equal to 7.06 kcal/mole and it is attributed to the polarization of the OH groups in the cellulose molecule. From the relation between the dielectric constant and the specific resistivity Rs, the dissociation energy U0 for the ground wood pulp was calculated. U0 for this sample below and above 52% RH is 0.315 and 5.13 × 10−12 erg, respectively. Also, the dissociation energy of Egyptian Ashmouny cotton was calculated. The variation of the electrical conductivity σ with humidity for different types of cellulosic materials is represented graphically.
Solute radical ion yields of γ‐irradiated aromatic compounds in poly(methyl methacrylate) at 77°K
Authors: Torikai Ayako , Kato Ryuzo
Published: April 2003

Ionic species in γ‐irradiated poly(methyl methacrylate) (PMMA) matrices were investigated. γ‐Irradiation of several aromatic solutes in PMMA gave rise to the radical cations and anions of the solutes. The limiting yields of radical cation and anion were determined to be 1.0–1.5 and 0.7–0.9, depending on the characteristics of the solutes, respectively. These values were compared with those in low‐molecular‐weight matrices. The distance of positive charge migration was estimated. The experimental results show that the charge transfer from PMMA to the solutes may be responsible for the formation of the radical cations and anions.
Thermal degradation of polybis(p‐isopropylphenoxy)‐phosphazene
Authors: Goldfarb Louis , Hann Nancy D. , Dieck Ronald L. , Messersmith David C.
Published: April 2003

Polybis(p‐isopropylphenoxy)phosphazene was treated thermally at 100, 135, 200, and 300°C. The resulting reductions in weight‐average molecular weights were monitored by gel‐permeation chromatography, and the experimental observations led to the adoption of a random chain‐scission model. An effective energy of activation and entropy of activation were calculated for the degradation process, and these values were found to be consistent with a random‐scission model. The analysis was, in part, based on a computer‐simulated first‐order degradation model. This polymer showed higher thermal stability than previously reported polyaryloxyphosphazenes.
Donor–acceptor complexes in copolymerization. LVIII. Alternating diene–dienophile copolymers. 12. Structure of furan–maleic anhydride copolymers prepared from the monomers and the diels‐Alder adduct
Authors: Gaylord Norman G. , Martan Michael , Deshpande Achyut B.
Published: April 2003

The copolymerization of furan with maleic anhydride in the presence of a perester or azobisiso‐butyronitrile at 50 or 70°C yields an unsaturated equimolar, alternating copolymer in which the furan units have 3,4 unsaturation and 2,5 linkages. The furan–maleic anhydride Diels‐Alder adduct undergoes retrograde dissociation in solution at 70°C and, in the presence of radical catalysts, yields the same unsaturated alternating copolymer as is obtained from the monomers. The adduct undergoes homopolymerization in the presence of a rapidly decomposing perester at 50°C to yield a saturated polymer having a rearranged structure containing 3‐oxabicyclo[2.2.1]heptane‐5,6‐dicarboxylic anhydride repeating units with 2,7 linkages.
Kinetic approach to radiation‐induced grafting in the polyethylene–styrene system. III
Authors: Imai Masahiko
Published: April 2003

The method of investigation reported in previous papers was applied to preirradiation methods of reaction in vapor and in liquid. The absorption dose was varied from 2 to 0.1 Mrad. The monomer concentrations during reactions were determined gravimetrically. The patterns of increase of the degree of grafting did not change as the dose was varied in the liquid but changed considerably with dose in the vapor. The monomer concentration during the reaction did not vary with dose in the liquid but did so in the vapor. A model calculation was applied and improved to make the monomer concentration agree with that in the experiment. An attempt was made to describe the mechanism involved. There were some differences between the calculated values and the experimentally obtained ones, but the outline of the reaction mechanism was explained satisfactorily.
Das Monte Carlo‐studium der verteilung der sequenzen in den copolymeren des methylmethacrylats mit chloropren und des 2‐hydroxyäthyl‐methacrylats mit alkylacrylaten
Authors: Motoc I. , Holban St. , Vancea R.
Published: April 2003

Using our Monte Carlo model of binary copolymerization, one studies the sequence distribution in methyl methacrylate/chloroprene and 2‐hydroxyethyl methacrylate/alkyl acrylate copolymers. Our study points out incontestably that the copolymerization of methyl methacrylate is explainable through ultimate group effect (Ebdon has stated a penultimate group effect). In the case of 2‐hydroxyethyl methacrylate/alkyl acrylate copolymers the agreement between computed and experimental data is satisfactory.
Interaction of polyesters with epoxy polymers: Insertion of oxirane rings into ester bonds
Authors: Komarova L. I. , Salazkin S. N. , Bulgakova I. A. , Malaniya M. I. , Vinogradova S. V. , Korshak V. V.
Published: April 2003

Epoxy oligomers readily interact (hardening) with polyesters of different structures (heterochain, carbochain, aliphatic, aromatic), as indicated by the change of properties and infrared spectra of an epoxy polymer–polyester composition on heating. The curing is caused by the reaction of the oxirane ring with ester groups and proceeds by the mechanism of “insertion” of the fragment of the oxirane cycle into the ester bond without scission of the molecular chain of polyesters. This mechanism of interaction is confirmed by study of a model reaction of phenyl benzoate with phenylglycide ether to lead to the formation of 1,3‐diphenyl ether of 2‐benzoyl glycerine. The latter was also produced by another way. The reaction of polyarylate with phenylglycide ether confirmed also that interaction of the ester group with the oxirane ring proceeds by the mechanism of “insertion.” This interaction proceeds with a high conversion and without rupture of the macromolecules (molecular weight does not decrease). The reaction of the oxirane ring with the ester group is accelerated in the presence of sodium salts of carboxylic acids, carbonic acid, and sodium phenolates.
Syntheses of polyamides and polybenzodipyrrolediones from pseudo diacetylphthaloyl chlorides and diamines
Authors: Ueda Mitsuru , Takahashi Takeyoshi , Imai Yoshio
Published: April 2003

Novel diacetylphthalic acids, 2,5‐diacetylterephthalic and 4,6‐diacetylisophthalic acids, were synthesized starting from pyromellitic dianhydride. These diacids were subsequently converted to the corresponding pseudo diacetylphthaloyl chlorides. The ring‐opening polyaddition, followed by dehydrochlorination, of the pseudo diacetylphthaloyl chlorides with aliphatic diamines in a polar aprotic solvent afforded almost quantitatively polyamides having inherent viscosities of 0.3–0.7. The solution polymerization was almost completed within 1 hr at room temperature. These polyamides were soluble in acidic solvents like m‐cresol. Subsequent cyclodehydration of the polyamides by heating at 200°C gave insoluble polybenzodipyrrolediones, which underwent weight losses of 10% at around 400°C under nitrogen.
Poly[2,2‐dimethyl‐4‐(methoxylcarbonyl) butylene]: Synthesis with an ethylaluminum sesquichloride–peroxide initiator and NMR characterization
Authors: Kuntz I. , Chamberlain N. F. , Stehling F. J.
Published: April 2003

The alternating copolymer of isobutylene and methyl acrylate (the polymer of the title) has been obtained by using ethylaluminum sesquichloride (AlEt1.5Cl1.5) and 2‐methylpentanoyl peroxide as the initiating system in benzene solution. The alternating copolymer is obtained at an acrylate/Al molar ratio of 17. Higher ratios increase the level of acrylate residues in the copolymer isolated; in the absence of AlEt1.5Cl1.5, an equal molar feed gives a copolymer with 75 mole % acrylate units. 1H‐ and 13C‐NMR spectra have been used to study the details of polymer structure and support the equal molar, alternating nature of the macromolecule. The details of the methoxy and gem‐dimethyl peaks in the PMR spectra are consistent with a Bernoullian process determining the polymer configurational sequences, with Pm = 0.55–0.60.
Grafting onto wool. III. Graft copolymerization of poly(vinyl acetate) by use of fenton's reagent as initiator
Authors: Misra B. N. , Chandel P. S. , Dogra Ramesh
Published: April 2003

In an attempt to modify fibrous protein, poly(vinyl acetate) has been graft copolymerized onto Himachali wool in an aqueous medium by using Fenton's reagent as redox initiator. Graft copolymerizations were carried out at 25, 30, 35, 40, and 45°C for a period of 3 hr. Percentage grafting was found to be dependent upon reaction temperature, concentration of monomers, and the molar ratio of [H2O2]/[Fe+2]. Maximum grafting occurred at 45°C with a molar ratio of [H2O2]/[Fe+2] = 1.43. A small amount of grafting (2.6–2.8%) occurred when grafting was effected at 45°C in the presence of Fe+2 alone.
Sequence distribution of repeating units of copolyamides by interfacial or solution methods
Authors: Ogata Naoya , Sanui Kohei , Kamiyama Shiro
Published: April 2003

The sequence distribution of repeating units of copolyamides from different diamines with isophthaloyl or terephthaloyl chlorides and dithiophenyl adipate have been investigated either by interfacial or solution methods to aim at the sequence control of the copolyamides by solvents.

Copolycondensation of dithiophenyl adipate and isophthaloyl chloride with m‐xylylenediamine in various solvents yielded copolyamides having different compositions of repeating units. Aprotic polar solvents produced random copolyamides having the same compositions as feed ratios of the comonomers, while nonpolar solvents yielded copolyamides rich in isophthaloyl units. Also the sequence distribution of the copolyamides from m‐ and p‐phenylenediamines with isophthaloyl chloride was affected by solvents; nonpolar solvents produced copolyamides having a less‐random and block character of the repeating units either by interfacial or solution methods.
Dielectric study of viscose rayon and viscose hydrocelluloses. II
Authors: Shinouda H. G. , Hanna A. A. , Kinawi A.
Published: April 2003

The effect of temperature on the dielectric properties of viscose fibers as well as of some of its acid‐modified residues was investigated. The results obtained show that: first, the change in the fine structure accompanying the acid degradation of the fibers has little, if any, effect on the location of the β peaks at any given temperature; second, the thermal transition of viscose fibers disappears with the late hydrolyzed vacuum‐dried residues. These results are discussed in the light of infrared spectra of the OH stretching vibration as well as specific volume data.
New polyphenylquinoxalines linked by m‐terphenyl flexibilizing groups
Authors: Rabilloud Guy , Sillion Bernard
Published: April 2003

Three new monomers with phenylglyoxyloyl groups fixed on the 4,4′‐, 4,6′‐, and 4,4″‐positions of m‐terphenyl were synthesized by different pathways. They were used to prepare a series of polyphenylquinoxalines by solution polycondensation with 3,3′‐diaminobenzidine and 3,3′,4,4′‐tetraaminodiphenyl ether. These polymers exhibited excellent oxidative and thermal stability as shown by thermogravimetric analysis and isothermal aging in circulating air between 300 and 450°C. Clear yellow films, cast from m‐cresol solution, were used to measure their softening temperature by thermomechanical analysis (TMA). Numerical data thus obtained, indicated a thermoplastic behavior in the temperature range 300 ± 15°C. Crosslinking of the linear polymers by isothermal heat exposure under argon between 300 and 500°C was investigated by means of TMA. Molded materials were fabricated under constant pressure (996 psi) at 500–525°C with an Instron testing machine. These polymers were also used for preliminary evaluation as matrices for 181‐E glass reinforced composites. Flexural values obtained after isothermal aging in air up to 400°C indicated a potential use varying from 150 hr at 350°C to 24 hr at 400°C.