bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vinyl polymerization initiated by system of organic halides and tertiary amines
Authors: Otsu Takayuki , Aoki Shuzo , Itakura Keisuke 
Published: April 2003

AbstractA study of the polymerization of vinyl monomers with binary systems of tertiary amines and various organic halides containing chemical bonds such as CCl, NCl, OCl, SCl, and SiCl has been made at 60°C. Some of the binary systems were found to be effective as radical initiator in the polymerization of methyl methacrylate. The relative initiating activities of the halides in the presence of dimethylaniline were found to be in the following order: tert‐C4H9OCl > n‐C4H9NCl2 > (n‐C4H9)2NCl ≫ CH3SiCl3 ⋍ C6H5SiCl3 > C6H5SO2Cl > C6H5Cl > C6H5PCl2. Styrene and vinyl acetate polymerized only with the initiator system of dimethylaniline and benzyl chloride. Tri‐n‐butylamine was less active than dimethylaniline. Pyridine and 4‐vinylpyridine, in combination with some organic halides, also initiated the polymerization of methyl methacrylate. The N‐vinylcarbazole–benzenesulfonyl chloride system, in the presence of methyl methacrylate, gave only the homopolymer of N‐vinylcarbazole.
Studies in cyclocopolymerization. VI. Copolymerization of trimethylvinylsilane and dimethyldivinylsilane with maleic anhydride
Authors: Butler George B. , Campus Alfred F. 
Published: April 2003

AbstractThis paper reports the results of copolymerization of trimethylvinylsilane and dimethyldivinylsilane, respectively, with maleic anhydride. The former forms a 1:1 alternating copolymer while the latter, being a 1,4‐pentadiene, forms a 1:2 cyclocopolymer. Consistent with the theory that charge‐transfer complexes are involved in certain copolymerizations, it has been shown in this work that both of the vinyl silanes studied form charge‐transfer complexes with maleic anhydride. The stoichiometric composition of these complexes have been shown by ultraviolet analysis to be 1:1 molar complexes. The equilibrium constants for complexation of trimethylvinylsilane and dimethyldivinylsilane with maleic anhydride have been determined by NMR and are 0.061 and 0.1071./mole, respectively.
Effect of lithium alkoxide and hydroxide on polymerization initiated with alkyllithium
Authors: Hsieh H. L. 
Published: April 2003

AbstractThe effects of lithium tert‐butoxide on rates of initiation, propagation, and polymerization of butyllithium‐initiated polymerization of butadiene and styrene were examined. Toluene and cyclohexane were used as solvent and the experiments covered BuLi/‐t‐BuOLi ratios from 1:0 to 1:6. Both polymerization and propagation rates declined in the presence of alkoxide. The initiation rate in cyclohexane increased to a maximum at BuLi/t‐BuOLi ratio of 1:0.5 and then decreased. A mechanism of rapid dissociation of butyllithium oligomer by alkoxide and multiple complexation of butyllithium with excess alkoxide is proposed. Lithium alkoxide also reduced the copolymerization rate but did not affect the copolymerization characteristies. Water reacted with organolithium compound rapidly to form hydroxide. It was found that the hydroxide reacted very slowly with more organolithium compound in hydrocarbon solution to form oxide. Their effects on polymerization were investigated.
Graft copolymerization of methyl methacrylate to poly(vinyl alcohol) initiated by ferric ion‐hydrogen peroxide system
Authors: Ogiwara Yoshitaka , Uchiyama Masahiro 
Published: April 2003

AbstractThe reaction occurring on treatment of samples of poly(vinyl alcohol) previously oxidized by sodium hypochlorite with ferric ion and hydrogen peroxide was studied. The graft copolymerization taking place on adding methyl methacrylate to the above system was also studied. Early in the reaction there was a period during which hydrogen peroxide was greatly reduced by the poly(vinyl alcohol), and this corresponded with a rapid cleavage reaction of the main chain of the polymer. Moreover, it was found that the reaction was quantitatively proportional to the formation of carbonyl groups in the sample. On the other hand, very few grafts were scarcely formed during this period; they formed by a mild reaction which took place immediately after this period. It seems that this behavior is quite different from that observed with the ceric ion initiating system. It is presumed that the formation of grafts is due to radicals formed by the cleavage of the main chain, and that the structure of the copolymer so formed is something like a block polymer.
Formation of diethylene glycol as a side reaction during production of polyethylene terephthalate
Authors: Hovenkamp S. G. , Munting J. P. 
Published: April 2003

AbstractPolymers of poly(ethylene terephthalate) (PET) always contain a certain amount of incorporated diethylene glycol (DEG), substituting the incorporated glycol. DEG is formed in a side reaction during the ester interchange of dimethyl terephthalate (DMT) with ethylene glycol or during direct esterification of terephthalic acid with ethylene glycol, and to a smaller extent during the polycondensation of the low‐molecular material. DEG is formed via an unusual type of reaction: ester + alcohol → ether + acid. Some evidence of this type of reaction is given by the formation of dioxane in low molecular PET and of methyl Cellosolve and methyl carbitol during the ester interchange of DMT with ethylene glycol and diethylene glycol, respectively. The strongest support for this type of reaction, however, was obtained from kinetic data. Polyesters of low molecular weight with OH group contents ranging from 3 to 0.5 mole/kg were heated at 270°C in sealed tubes for 1–7 hr. The kinetic equation for the proposed reaction is: d[DEG]/dt = k[OH] [ester]. With the aid of one rate constant the formation of DEG in all esters could be described.
Radical and radiation‐induced grafting of some synthetic high polymers within the temperature range of their glass transition
Authors: Schamberg Eckehard , Hoigné Jürg 
Published: April 2003

AbstractThe temperature dependence of radiation‐induced grafting onto poly(ethylene terephthalate), polyamides, polyacrylonitrile, and polypropylene has been investigated for several monomers. In all cases a maximum grafting yield is obtained when the reaction is performed in the temperature range of the glass transition Tg of the polymer used. This maximum yield does not only appear with radiation‐induced simultaneous grafting. It also appears when the graft polymerization is induced by pre‐irradiation or even by thermal decomposition of organic peroxides. It is assumed that the pronounced maximum of the reactivity at Tg is obtained because in the glassy state below Tg the radicals formed cannot react due to a reduced diffusion of the monomer, whereas above Tg the number of radicals available for polymerization will be reduced with increasing temperature.
Chain scission of butyl rubber by nitrogen dioxide in absence and presence of air
Authors: Jellinek H. H. G. , Flajsman F. 
Published: April 2003

AbstractThe chain scission reaction suffered by butyl rubber due to NO2 (0.01‐1 mm Hg) has been studied in the presence and absence of air. It has also been studied as a function of temperature (25–65°C) at constant NO2 pressure, again in absence and presence of 1 atm of air. Reaction mechanisms which are in good agreement with the experimental results have been formulated. The synergistic action of O2 and NO2 has been pointed out.
Studies of the polymerization of diallyl compounds. VII. Kinetics of the polymerization of diallyl esters of aliphatic dicarboxylic acids
Authors: Matsumoto Akira , Oiwa Masayoshi 
Published: April 2003

AbstractRadical polymerization studies on diallyl oxalate (DAO), diallyl malonate (DAM), diallyl succinate (DASu), diallyl adipate (DAA), and diallyl sebacate (DAS) have been conducted kinetically from the standpoint of cyclopolymerization. Benzoyl peroxide was employed as the initiator. The initial overall rate of polymerization, Rp was not proportional to the square root or the first power of the initiator concentration, [I]. But Rp/[I]1/2 and [I]1/2 bore a linear relationship, provided the monomer concentration was kept constant. The residual unsaturation of the polymers decreased with decreasing monomer concentration. The ratio of the rate constant of the unimolecular cyclization reaction to that of the bimolecular propagation reaction of the uncyclized radical, Kc, was evaluated from the above relationship between the residual unsaturation and the monomer concentration at 60°C. The Kc values obtained were 3.6, 3.2, 2.8, 2.5, and 1.2 mole/l. for DAO, DAM, DASu, DAA, and DAS, respectively.The overall activation energies of polymerization were found to be 21.1 (DAO), 24.2 (DAM), 21.7 (DASu), 22.0 (DAA), and 22.2 (DAS) kcal/mole.
Crosslinking, filler, or transition constraint of polymer networks. I
Authors: Blanchard A. F. 
Published: April 2003

AbstractThe basic theory of modulus/swelling is developed to allow for limited extensibility, filler reinforcement or transition effects, and steric hindrance of aligned segments by extended chains or filler particles.Filler forms an effective hard fraction Ch per cubic centimeter of compound with vc a new (compound) index of swelling. For 1/Mc + σ fix points having ratio φ to gum values 1/F0(vr) and with F(vc) replacing the Flory function F(vr):

where σ denotes entanglement. Linkage reinforcement φ does not vary with sulfur crosslinking of SBR. Vacuoles invalidate φ from mass‐increment F0(vr)/F(vr) for inert fillers. Then, or for Graphon, with negligible φ ≈ 1:

The effective Ch includes rubber stretched hard on Graphon by swelling or trapped inside hard aggregates. Only the right‐hand equation fits normal blacks. In theory, Ch can always be obtained from swollen moduli G by linear slopes (1 + 1.4Ch) relating F(vc) and (1 − C)ρRT/G. For filler fractions C ≥ 0 cm−3 and low strains α = 1.5−2.0 below prestretch the modulus G is given a new basic definition:

Here C2* ≈ 0.7 corresponds to Mooney‐Rivlin C2 and the effective crosslinking 1/[Mc] = (ρRT)−1G is equal to (1 − C)(1/Mc + σ) for unswollen prestretched rubber (vr = 1). For higher strains a hypothesis of strain hardening is proposed. This is distinct and opposite in character to the initial prestretch softening (Mullins effect). Nonlinear effects of crosslinks are expressed by a fractional stress‐upturn Ω (1/Mc + σ), effective mesh wieght (1/Mc + σ)−1 − Ω, and hard fraction Ω(1/Mc + σ). For μh characterizing strain hardening up to the prestretch (αh − 1) their contribution is:

The sixth‐power refinement has J = j(αb − 1)1/2 with j ≈ 0.4. The hard phase is augmented by filler and grows with increasing strain up to the prestretch.
Studies on monomer reactivity ratios. II. A charge‐transfer model
Authors: Hoyland James R. 
Published: April 2003

AbstractA charge‐transfer model is proposed for the treatment of monomer reactivity ratios in free‐radical bulk polymerization. The procedure involves the assignment of three parameters to each monomer, which can be interpreted as being related to the energies of the highest occupied monomer orbital, the singly occupied radical orbital, and the lowest lying virtual orbital of the monomer. Parameters are found for 17 monomers and computed reactivity ratios for a large number of copolymer systems are tabulated and compared with experiment. Similarities of the present model and the electronegativity scheme are discussed.
Stereoregular poly(styrenesulfonic acid)
Authors: Aylward N. N. 
Published: April 2003

AbstractA convenient method is described for the preparation of poly(n‐propyl p‐vinylbenzene sulfonate) by using the monomer, n‐propyl p‐vinylbenzene sulfonate and butyllithium initiation in tetrahydrofuran at −75°C. The structure of this polymer enables complete hydrolysis to the corresponding poly(styrenesulfonic acid), which was characterized with respect to molecular weight and sulfonic acid content. The polyacid was shown by potentiometric titration to be strongly ionophoric.
Preparation of optically active N‐bornyl maleimide and poly(N‐bornyl maleimide)
Authors: Yamaguchi Hidemasa , Minoura Yuji 
Published: April 2003

AbstractOptically active N‐bornyl maleimide (NBMI) was prepared with maleie anhydride and d‐camphor amine and the polymerizations of N‐bornyl maleimide were carried out with benzoyl peroxide (BPO), α,α′‐azobisisobutyronitrile (AIBN) and n‐butyllithium. The specific rotations of the polymers obtained by BPO, AIBN, and n‐BuLi were +5.1 to +8.4, +10.0 to +10.1 and −7.0 to −9.0, respectively. The results of the x‐ray analysis for the above polymers showed that these polymers had the same structure. The specific rotation of the polymer initiated by BPO increased with increasing intrinsic viscosity. The effect of the polymer endgroup on the specific rotation was discussed.
Thermal behavior of poly‐p‐xylylene‐m‐carborane
Authors: Delman Alvin D. 
Published: April 2003

AbstractThermal analysis, infrared spectroscopy, and gel‐permeation chromatography studies were undertaken to determine the behavior of poly(p‐xylylene‐m‐carborane) at elevated temperature. Results show that the polymer softened at about 200°C, probably because of polymorphism. Chlorine atoms from chain ends also ruptured at this temperature. This initiated subsequent hydrogen abstraction and thermal oxidation reactions that resulted in the decomposition of the polymer. The process of degradation closely parallels the thermal oxidation of polybenzyl and other polymers with readily activated methylene groups. The volatile products that formed at 300 and 400°C were produced because of the cleavage of methylene groups and their oxidation products. Larger polymer segments containing phenylene and m‐carborane groups were evolved at higher temperatures. Some crosslinking occurred when the polymer was heated in air at temperatures above 200°C. The degree of polydispersity of the polymer fraction that remained soluble in organic solvents increased with corresponding increase of temperature.
Thermal degradation of thin films of isotactic polypropylene and polypropylene with ketonic additives
Authors: Abu‐Isa Ismat 
Published: April 2003

AbstractThe rate of oxidation of 0.3–0.7 mil films of pure polypropylene is much more rapid than with thicker films. The rate of oxidation increases with the increase in the partial pressure of oxygen and with temperature. The apparent activation energy in oxygen is 22.5 keal/mole. 1,3‐Diphenyl‐2‐propanone added to the polymer acts as an oxidation initiator while p‐phenylacetophenone and 4‐phenylbenzophenone slightly retard the oxidation. The effects of the additives are more pronounced when the oxidation was carried out in air or at the lower temperatures (90°C) when the oxidation was conducted in pure oxygen. The degree of crystallinity based on the infrared data was found to increase with the degree of oxidation of the polymer.
Electrochemical polymerization to a controlled molecular weight distribution
Authors: Funt B. Lionel , Richardson Derek R. 
Published: April 2003

AbstractLiving polyanions were generated by the passage of electrolytic current through solutions in tetrahydrofuran (THF). The concentration of living polyanions was controlled by the current and could be increased by further electrolysis or decreased by electrolysis with reversal of polarity. Inasmuch as the living end (LE) concentration determines the molecular weight at a given monomer concentration it was possible to program a molecular weight distribution. Model distributions were attempted by (1) indirect methods in which an electrolytic formation of initiating dianions was followed by monomer addition, polymerization, current reversal and further polymerization and (2) direct methods in which monomer was present throughout the electrolysis. The molecular weight distributions were obtained by gel‐permeation chromatography and corresponded closely to the values calculated from the simple kinetic model of anionic polymerization. For styrene a sharp low molecular weight fraction and a clear binodal high molecular weight fraction were obtained. The binodal character was attributed to the growth of active single‐ended and double‐ended polyanions. The yields of high and low molecular weight material, the ratios of molecular weights obtained, and the values of the molecular weights were in agreement with expectation. The direct electrochemical polymerization methods were employed for α‐methylstyrene, but the high kp for styrene thwarted efforts to apply the direct technique with this monomer.
New information on the alternating copolymerization of butadiene‐1,3 with acrylonitrile
Authors: Furukawa Junji , Iseda Yutaka , Haga Kazuo , Kataoka Nobuyuki 
Published: April 2003

AbstractButadiene‐1,3 and acrylonitrile were copolymerized by alkylaluminum halides alone or, more effectively, by the alkylaluminum halide/vanadium compound systems, into an alternating copolymer in which the butadiene units are linked predominantly in the trans‐1,4 configuration. The efficiency of the aluminum components in the latter catalyst systems appear to decrease in the following order: AlEtCl2 > Al2Et3Cl3 ≫ AlEt2Cl(≫AlCl3). The alkylaluminum halides could also be used effectually in the form of the complex with acrylonitrile. The catalytic activity was markedly affected by the order of mixing of the catalyst components and the monomers. Effective catalysts could be prepared only when the catalyst components were mixed in the presence of acrylonitrile. The catalyst activity was also found to depend upon the Al/V ratio, reaching its maximum when the ratio was about 20 in the AlEtCl2·AN/VO(Ot‐Bu)3 system. Other combinations of conjugated diene with conjugated polar vinyl monomer were similarly copolymerized by these catalysts. It was found that different feed ratios between the diene and the vinyl monomer which were varied over a wide range always resulted in the formation of a 1:1 copolymer. The butadiene‐acrylonitrile copolymer thus formed gave an NMR spectrum in which there was only one peak assignable to the methylene protons (7.72 τ) of the butadiene unit. On the basis of these findings, it may be suggested that alternating copolymerization prevails in the polymerization systems here investigated.
GPC analysis of model compounds. I. Phenyl‐ and benzo‐substituted aromatic compounds
Authors: Thompson R. E. , Sweeney E. G. , Ford D. C. 
Published: April 2003

AbstractA series of 36 compounds of known structure was used in a study to elucidate the mechanism of separation of gel‐permeation chromatography (GPC). The various molecular dimensions were defined and measured for these compounds. The elution volume for these compounds was determined by GPC under specified and controlled conditions. The relationships between elution volume and molecular dimension were investigated using computer‐based statistical analysis for the entire set of compounds and manual simultaneous equations for smaller sets of compounds. It was found that, as increasingly more molecular dimensions are considered, (1) the importance of the maximum molecular dimension Ap′ (the only dimension considered by many investigators) significantly decreases and (2) a significantly better prediction of the elution volume of these compounds could be made.
Line‐intersection method for determining the configurational parameters of cross propagation in copolymerization
Authors: Klesper E. 
Published: April 2003

AbstractFor the evaluation of the configurational parameters in cross propagation, Σs and Σp for binary vinyl type copolymers whose monomer units both contain an asymmetric carbon atom in the chain, a method is proposed which relies on intersecting straight lines in a Σs versus Σp diagram. We define Σs = σAB + σAB and Σp = σAB·σBA, σ being the probability of forming an isotactic enchainment between the monomer units when B adds to a chain ending in A, or A adds to a chain ending in B, respectively. For these definitions it is assumed that σAB and σBA are not necessarily equal in their numerical values. The method described is applicable to triad probabilities obtained both from copolymers and such homopolymers which have been prepared from copolymers under retention of configuration by a polymer analogous reaction. In this work, triad data have been evaluated which were obtained by NMR from methyl methacrylate‐methacrylic acid copolymers, wherein the methyl methacrylate units were pentadeuterated on the αCH3 and βCH2 groups, as well as from methyl methacrylate homopolymers, the latter being prepared from undeuterated methyl methacrylate‐methacrylic acid copolymers by esterification. The approximate values Σs = 0.38, Σp = 0.02 were obtained for the deuterated copolymers, while Σs = 0.392 ± 0.003 and Σp = 0.037 ± 0.003 were found for the undeuterated homopolymers.
Study of the thermal dehydrochlorination of poly(vinylidene chloride) and poly(vinyl chloride) by ESR spectroscopy
Authors: Hay J. N. 
Published: April 2003

AbstractThe evidence for a radical elimination of hydrogen chloride during the thermal degradation of homopolymers and copolymers of vinylidene chloride is summarized and confirmed by an ESR spectroscopic study of the degradation residues. However, sufficient differences in the degradation characteristics exist between these polymers and those of vinyl chloride to suggest that a radical process alone is not sufficient. No evidence of a radical process can be obtained from an ESR spectroscopic analysis of the elimination. The paramagnetic character of the degraded polymer is attributed to the polyene structure produced on dehydrochlorination.
Depolymerization behavior of nylon 6 anionically obtained with NaAL(Lac)4 at high temperature
Authors: Konomi T. , Tani H. 
Published: April 2003

AbstractDepolymerization and consumption of catalyst in the polymerizing system were investigated in the polymerization of ϵ‐caprolactam by using NaAl(Lac)4 catalyst at 255°C. In the first stage of depolymerization, marked consumption of catalyst was observed. The relationship between the degree of polymerization of resulting polymer and the catalyst concentration, during the polymerization time from 10 min to 3 hr, was different from that observed for the final polymer in the case of sodium phenylacetate or sodium catalyst, and follows the equation, Pn ∞ 1/[Lac].0.4 This behavior is ascribed to the peculiar catalytic behavior of Al(Lac)3, which is a component of this catalyst.
Kinetics and mechanism of polymerization yielding stereoblock poly(methyl methacrylate) with VCl4‐Al(C2H5)3 catalyst system
Authors: Dixit Sunit S. , Deshpande A. B. , Kapur S. L. 
Published: April 2003

AbstractMethyl methacrylate was polymerized at 40°C with the VCl4–AlEt3 catalyst system in n‐hexane. The rate of polymerization was proportional to the catalyst and monomer concentration at Al/V ratio of 2, indicating a coordinate anionic mechanism of polymerization. NMR spectra were further used to confirm the mechanism of polymerization and stability of active sites responsible for isotacticity.