bluuebunny/crossref_metadata_2025 huggingface dataset:
Chromatographic fractionation of polystyrene: An evaluation of the nature of column fractionation
Authors: Yamaguchi Kinya , Saeda Shigeru
Published: April 2003

Column chromatographic fractionation of polystyrene was carried out with the methyl‐ethyl ketone–methanol system, and effects of various experimental conditions on the fractionation efficiency were studied. For samples with molecular weights below about 6 × 105, neither the temperature gradient (0.7°C/cm), nor the flow rate of solvent (30–270 ml/hr) seriously influences the fractionation efficiency. The effect of temperature gradient becomes apparent only in the high molecular weight region and only if the gradient of the solvent composition is too steep. High flow rates (ca. 125 ml/hr) clearly affect the fractionation efficiency for a high molecular weight sample (Mw = 5.46 × 105). Precipitation chromatography for the fractionation system was calculated from the phase equilibrium data according to the mass transport equation proposed by Schulz et al. The theoretical analysis gives support to the observed dependence of the temperature effect on molecular weight. Comparison of the observed and theoretical relations between elution volume and molecular weight of the fraction, on the other hand, indicates that the process of fractionation is simply elution of polymer off the support without reprecipitation. Certain conditions of polymer deposition on the support are required for optimal results.
Formation of kink bands in oriented polymers
Authors: Robertson Richard E.
Published: April 2003

The circumstances of the formation of kink bands have been investigated with a newly designed shearing device and light and electron microscopes. Kink bands having sharp edges and reflection symmetry about the edges were formed and studied in the two crystalline polymers, high‐density polyethylene and isotactic polypropylene, but could not be formed in the two glassy polymers, poly(4,4′‐dioxydiphenyl‐2,2‐propane carbonate) and poly(2,6‐dimethylphenylene oxide). The characteristics of the oriented polymer that promote kink bands seem to be easy slip along the orientation axis, and resistance of the oriented fibrils to length changes. Kink bands were found to initiate at sites of shear stress concentration, where the fibrils are first deformed into an S‐shaped curve, that then tightens and finally collapses into kinks.
Melting temperatures of poly(2,6‐dimethyl‐1,4‐phenylene oxide) in methylene chloride solutions: Thermodynamic analysis
Authors: Shultz A. R. , McCullough C. R.
Published: April 2003

Melting temperatures were observed visually for poly‐(2,6‐dimethyl‐1,4‐phenylene oxide) in methylene chloride at nine concentrations (polymer weight fractions ranging from 0.0042 to 0.2362). The data were analyzed upon the assumptions that ΔHu and ΔSu, the molar heat and entropy of fusion per polymer unit, are constant over the temperature range studied, and that a Flory‐Huggins chemical potential expression with a concentration‐independent pair interaction parameter, χ1 = (0.5 + ψ1) + ψ1Φ/T, satisfactorily describes the polymer unit activity in the binary solutions. Computation gave ΔHu = 1404 cal/mole of units (therefore Δh = 11.7 cal/g), ψ1 = −0.5691, and Φ = 342.4°K. The effect of using various combinations of data points upon the values of these three parameters, as determined by least‐squares linear regression treatment of the melting temperature expression, is indicated.
Scattering of light from deformed regions surrounding voids and inclusions in high polymers
Authors: Stein Richard S. , Wilkes Garth L.
Published: April 2003

The Hv cloverleaf scattering pattern sometimes found for amorphous polymers can arise from the birefringent region caused by the strain surrounding a void or an inclusion in a polymer. The form of such a pattern may be theoretically explained by extension of a theory due to Goldstein.
Dielectric properties of polystyrene and some polychlorostyrenes from 4°K to room temperature
Authors: McCammon R. D. , Saba R. G. , Work R. N.
Published: April 2003

Dielectric measurements of carefully purified specimens of polystyrene and poly(2,3,4 or 3,4‐chlorostyrene) have been obtained at audio frequencies ranging from 0.1 to 20 kHz and at temperatures between 4 and 300°K. Each of the samples exhibits a dielectric loss maximum in the range 15–50°K. The temperature of the maximum loss decreases with the addition of a substituent which lowers the symmetry of the pendant phenyl group. The results are explained by a model which invokes a coupling mechanism between two distinct modes of side group motions. This same model also explains some results of previously reported measurements of mechanical losses in similar polymers.
Mixed crystal infrared study of chain folding in crystalline polyethylene
Authors: Bank M. I. , Krimm S.
Published: April 2003

Infrared spectroscopic studies have been made of mixed crystals of linear polyethylene and perdeuteropolyethylene. On the basis of normal vibration analyses by Tasumi and Krimm it had been shown that the study of crystal splittings of internal chain modes in such mixed crystals could provide information on the geometry of chain folding. The present results, which include a study of n‐paraffin (C36) mixed crystals, confirm these predictions. They show that (110) folding predominates in dilute solution grown crystals, and that this is transformed to (200) folding in melt‐crystallized polymer. Folding with adjacent re‐entry is favored, a random re‐entry model being clearly eliminated.
Dielectric relaxation of high polymers in the solid state
Authors: Ishida Yōichi
Published: April 2003

Dielectric relaxation processes observed in solid polar polymers seem to be generally classified into three kinds. Amorphous polymers with flexible polar side groups usually show two kinds of relaxation process. The high‐temperature process is attributed to the large scale conformational rearrangements of the main chains, while the low‐temperature one results from the motion of side groups. We shall call the former αa relaxation and the latter β relaxation, where the subscript refers to the amorphous phase. Even in amorphous polymers without flexible side groups, two processes are observed. The molecular mechanism of high temperature one is the same as the αa relaxation. The low‐temperature one is due to the “local relaxation mode” of the main chains. We shall call it also β relaxation because of the similarity of the observed characteristics. Semicrystalline polymers show two relaxation processes classified as αa and β, although their behavior is modified by crystallization. When the crystallinity is greatly increased, a third relaxation process with associated with crystalline phase appears. We shall call it αc relaxation, where the subscript means the crystalline phase. The effects of chemical structure, stereoregularity, pressure, and crystallization on the dielectric behavior can be explained consistently based on the above molecular mechanisms.
Studies of branching in polyvinyl acetate
Authors: Graessley William W. , Hartung Ralph D. , Uy William C.
Published: April 2003

Batch polymerizations of vinyl acetate were conducted at 60°C and 72°C, and rate constants for branching were established from the variation of M̄n and M̄w with extent of conversion. The calculated branching densities (branch points per polymer molecule) are slightly higher at 72°C for all conversions. Selected samples were saponified and reacetylated to determine the amount of branching through the acetate group. Changes in M̄n, M̄w, and [η] indicate 63%, 75%, and 70%, respectively, of saponificable branches. These percentages are independent of branching density in the original polymer. Molecular weights extrapolated to zero conversion appear to be unchanged by saponification and reacetylation, showing that short chain branching through the acetate group is absent, or at least very infrequent.
Drawing of single‐crystal mats of linear polyethylene
Authors: Ishikawa Kinzo , Miyasaka Keizo , Maeda Masahiko
Published: April 2003

Drawing of single‐crystal mats of linear polyethylene has been investigated. Drawing is possible at temperatures higher than about 90°C. The drawing is accompanied by distinct necking, with a large decrease in the thickness of the mat and a very high maximum draw ratio, sometimes over 30. The maximum draw ratio is approximately proportional to the thickness of the lamellae. This behavior strongly suggests the unfolding of chains during drawing. A change of orientation of crystal axes occurs before necking without change of lamellar orientation. The a axis orients in the drawing direction; the b axis orients perpendicular to the direction of drawing; and the chain axis tilts away from the thickness direction of the mat. The structure of films drawn from mats is characterized by a distinct double orientation of crystals. This biaxial orientation in the drawn films has a high degree of correlation with the orientation of crystal axes observed before necking, and suggests that necking takes place in such a way that the chain tilts gradually about the b axis and ultimately unfolds. The postulate of formation of transitory two‐dimensional crystals in necking seems useful in explaining the double orientation in the drawn film. The orientation behavior of crystal axes observed before necking is not always similar to that observed in the deformation of a single crystal. The difference is thought to be due to the effect of forces induced by drawing that act in the direction normal to the lamellae within a mat.
Extended‐chain crystals. IV. Melting under equilibrium conditions
Authors: Prime R. Bruce , Wunderlich Berhard
Published: April 2003

Dilatometric melting experiments were performed on an extended‐chain crystalline polyethylene with a broad molecular weight distribution and on four samples crystallized from fractionated polyethylenes. The melting curves were compared with computer calculations based on the assumption of eutectic separation. For the fraction of lowest molecular weight, agreement between experiment and calculation was achieved. The melting behavior of all other samples indicated that only for molecular weights up to 10,000–12,000 did eutectic separation occur. The higher molecular weight portion of each sample crystallized in the form of mixed crystals. Of the experimental maximum melting‐point lowering of these mixed crystals, 0.1–0.9°C is due to the lower molecular weight diluents. Another 2–3°C lowering in melting point is due to the fact that the phase diagram of polyethylene mixed crystals has a minimum.
Poly[tris(diorganophosphinato)alanes]
Authors: Flagg Edward E. , Schmidt Donald L.
Published: April 2003

Poly[tris(diorganophosphinato)alanes], [Al(OPRR′O)3]n, were synthesized in which the organic moieties (R,R′) contained from one to eighteen carbon atoms. Polymeric properties depended upon the organic moieties; polymers were fusible, tractable, and flexible when the organic moieties contained six or more carbon atoms. Soluble polymers were prepared by using mixtures of symmetrical and unsymmetrical phosphinates. One polymer, poly{bis[n‐butyl(benzyl)phosphinato]di‐n‐octylphosphinatoalane}, exhibited a degree of polymerization greater than 1000 and an exceptionally high intrinsic viscosity of 37 dl/g. The properties of the different polymers are discussed, and feasible structures are proposed.
Thermal degradation of poly(vinyl chloride). I. Structural effects in the initiation and decomposition chain lengths
Authors: Gupta V. P. , St. Pierre L. E.
Published: April 2003

Four poly(vinyl chloride) samples containing different structural irregularities were thermally decomposed. The rates of HCl evolution were compared to the rates of radical generation in the samples. Orders of stabilities related to the structural entities for the initiation of decomposition and for the chain lengths of HCl evolution were established.
Vinyl polymerization with Fe(III)–thiourea as initiator system. Part II. Kinetics: Predominant primary radical termination
Authors: Mandal B. M. , Nandi U. S. , Palit S. R.
Published: April 2003

The rate of polymerization Rp of methyl methacrylate initiated by Fe(CIO4)3 and thiourea (TU) in tert‐butyl alcohol is indepenent of [Fe(III)] and [TU] in the concentration range studied. In contrast to Rp, the degree of polymerization DP changes markedly with the change in the initiator concentration. DP is overwhelmingly lower than is expected in a standard radical polymerization at the same Rp. Further, Rp is proportional to the square of the monomer concentration. Initiation efficiency is less than one. Independent experiments proved that in the azobisisobutyronitrile‐initiated polymerization the Rp and DP are negligibly affected by [Fe(CIO4)3] or [TU], though high [TU] brings about high induction periods. The results of Fe(III)‐TU‐initiated polymerization have been interpreted in terms of the predominant termination of polymer radicals by primary radicals.
Characterization of styrene–acrylonitrile copolymer by pyrolysis gas chromatography
Authors: Vuković R. , Gnjatovic V.
Published: April 2003

Samples of styrene–acrylonitrile (SAN) copolymer of different compositions, molecular weights, block copolymers, and a blend of styrene and acrylonitrile homopolymers were prepared and characterized by the method of pyrolysis gas chromatography. On decomposition of SAN copolymer samples at 645°C, eleven components were identified, the most important of them being styrene, acrylonitrile, and propionitrile. By examination of the pyrolyzate composition during pyrolysis of the SAN copolymer of different compositions, it was established that the propionitrile yield was definitely decreased when the acrylonitrile concentration in copolymer was about 60 mole‐%. Further, from the propionitrile yield, we could distinguish random SAN copolymer from the styrene‐acrylonitrile homopolymer blend, and on the basis of propionitrile yield some information on the molecular structure of the copolymer could be obtained. The styrene yield depends linearly on the copolymer composition. This permits determination of copolymer composition on the basis of the styrene yield. Furthermore, the effects of decomposition temperature and of molecular weight on the yields of styrene and acrylonitrile were examined.
Interfacial syntheses of polyphosphonate and polyphosphate esters. II. Dependence of yield and molecular weight on solvent volumes and concentrations of comers in basic polymerization of hydroquinone and phenylphosphonic dichloride
Authors: Millich F. , Carraher C. E.
Published: April 2003

The interfacial polymerizations of hydroquinone with phenylphosphonic dichloride, in the presence of barium hydroxide or sodium hydroxide, were studied and contrasted. Polymer yields and molecular weights were shown to vary with concentration of the comer reactants, with the comer ratio, and with the relative amounts of carbon tetrachloride and aqueous phases, but not with concentration of barium ion. The latter supports the impression that the reaction zone is situated in the aqueous phase. The method of Millich and Carraher, employing pH control, yields products of high molecular weights and some results which are distinct from those achieved with the use of sodium hydroxide.
Polymerization of coordinated monomers. III. Copolymerization of acrylonitrile–zinc chloride, methacrylonitrile–zinc chloride or methyl methacrylate–zinc chloride complex with styrene
Authors: Ikegami Tadashi , Hirai Hidefumi
Published: April 2003

The 1:1 or 2:1 complex of acrylonitrile, methacrylonitrile, or methyl methacrylate with ZnCl2 was copolymerized with styrene at the temperature of 0–30°C without any initiator. The structure of the copolymer from methyl methacrylate complex and styrene was examined by NMR spectroscopy. The complexes of acrylonitrile or methacrylonitrile with ZnCl2 gave a copolymer containing about 50 mole‐% styrene units. The complexes of methyl methacrylate yielded an alternating copolymer when the feed molar ratio of methyl methacrylate to styrene was small, but with increasing feed molar ratio the resulting copolymer consisted of about 2 moles of methyl methacrylate per mole of styrene. The formation of a charge‐transfer complex of styrene with a monomer coordinated to zinc atom was inferred from the ultraviolet spectra. The regulation of the copolymerization was considered to be effected by the charge‐transfer complex. The copolymer resulting from the 2:1 methyl methacrylate–zinc chloride complex had no specific tacticity, whereas the copolymer from the 1:1 complex was richer in coisotacticity than in cosyndiotacticity. The change of the composition of the copolymer and its specific tacticity in the polymerization of the methyl methacrylate complex is related to the structure of the complex.
Precipitation of some nonionic polymers by octylammonium thiocyanate
Authors: Saito Shuji
Published: April 2003

The effects of various alkylammonium thiocyanates (ethyl, butyl, hexyl, and octyl) on aqueous solutions of polyvinylpyrrolidone (PVP) and poly(vinyl alcohol–acetate) copolymer (PVA‐Ac) were studied and compared with the effects caused by the respective chlorides. Whereas the PVP solution was hardly affected by the chlorides, it was precipitated by n‐octylammonium thiocyanate (OASCN) at dilute concentrations and dissolved at higher concentrations. On taking the effects of ammonium chloride and thiocyanate on the solubility of PVA‐Ac as references, with increasing of alkyl chain length, alkylammonium chlorides raised the polymer solubility steadily; on the contrary, the thiocyanates at dilute concentrations, except for ethylammonium thiocyanate, lowered it, and OASCN at dilute concentrations, except for ethylammonium thiocyanate, lowered it, and OASCN at dilute concentrations was a particularly strong salting‐out agent. The amount of binding of OASCN to the polymers in the precipitated systems was measured. The precipitation was attributed to ion‐pair binding of OASCN to the polymers, and the mechanism was discussed in terms of the interaction between the water structure‐breaking SCN− and the water structure‐making hydrophobic groups.
Alternating copolymerization of polar vinyl monomers in the presence of zinc chloride. III. NMR study of methyl methacrylate–styrene copolymer
Authors: Yabumoto Shigeru , Ishii Kiyoshi , Arita Koichiro
Published: April 2003

The copolymer composition curve of the methyl methacrylate–styrene copolymer obtained by the copolymerization in the presence of ZnCl2has more alternating tendency than that of ordinary methyl methacrylate–styrene copolymer obtained by radical copolymerization. The fine structure of the copolymer was examined by NMR, and the mechanism of the propagation step of the copolymerization in the presence of ZnCl2, which was proposed in the first report of this series, was verified.
Transient analysis of a viscoelastic torsion pendulum
Authors: Glauz R. D.
Published: April 2003

The transient torsion pendulum of arbitrary cross section is analyzed as a device for obtaining physical properties of a viscoelastic material. The damped sinusoidal motion yields a damping factor and frequency from which the complex modulus is computed. The particular cases of circular and rectangular cross section are considered with tables and approximations simplifying the practical application of the method.
Poly(ester‐acetals) from azelaaldehydic acid‐glycerol compounds
Authors: Miller W. R. , Awl R. A. , Pryde E. H. , Cowan J. C.
Published: April 2003

Poly(ester‐acetals) have been prepared from isopropylideneglyceryl azelaaldehydate dimethyl acetal and from methyl azelaaldehydate glycerol acetal. Acid hydrolysis of isopropylideneglyceryl azelaaldehydate led to oligomeric poly(ester‐acetals) with six to seven repeating units and carboxylic acid endgroups from which the sodium salt and the methyl ester could be prepared. The polymer sodium salt showed some surfactant properties. Methyl azelaaldehydate glycerol acetal, a mixture of geometric and structural isomers, was polymerized under typical polyesterification conditions. Lime was the best catalyst found. Molecular weights of 5000 to 12000 were obtained. Some of these polymers contained significant quantities of calcium as the carboxylate salt. A tough elastomer was prepared by heating a poly(ester‐acetal) with p‐toluenesulfonic acid and zine oxide.
Vinyl polymerization initiated by system of organic halides and tertiary amines
Authors: Otsu Takayuki , Aoki Shuzo , Itakura Keisuke
Published: April 2003

A 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

This 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

The 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

The 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

Polymers 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

The 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

The 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

Radical 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

The 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

A 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

A 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

Optically 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

Thermal 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

The 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

Living 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

Butadiene‐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

A 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

For 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

The 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

Depolymerization 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

Methyl 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.
Calorimetric investigation of polymerization reactions. III. Curing reaction of epoxides with amines
Authors: Horie K. , Hiura H. , Sawada M. , Mita I. , Kambe H.
Published: April 2003

The curing reactions of epoxy resin with aliphatic diamines and the reaction of phenyl glycidyl ether with butylamine as a model for the curing reactions were investigated with a differential scanning calorimeter (DSC) operated isothermally. The heat of reaction of phenyl glycidyl ether with butylamine is equal to 24.5 ± 0.6 kcal/mole. The rate of reaction was followed over the whole range of conversion for both model and curing reactions. The reactions are accelerated by the hydrogen‐bond donor produced in the system. The rate constants based on the third‐order kinetics were determined and discussed for the model reaction and for the chemically controlled region of curing reactions. The activation energies for these rate constants are 13‐14 kcal/mole. At a later stage of conversion, the curing reactions become controlled by diffusion of functional groups. The final extent of conversion is short of completion for most isothermally cured and even for postcured samples because of crosslinking. It was quantitatively indicated that the final conversion of isothermal cure corresponds to the transition of the system from a viscous liquid to a glass on the basis of the theory of glass transition temperature of crosslinked polymer systems.
Reduction of pendent ester groups in polycarbonates by use of diborane
Authors: White R. E. , Gardlund Z. G.
Published: April 2003

A series of polycarbonates with pendent ester groups have been synthesized. These ester groups have been converted to hydroxyl functionalities by reduction with diborane in tetrahydrofuran. The number of methylene groups in the pendent chain has a large effect on the reducibility of the ester.
Polymerization of vinyl chloride by alkyllithium compounds
Authors: Jíšová V. , Kolínský M. , Lím D.
Published: April 2003

The polymerization of vinyl chloride initiated by alkyllithium compounds was investigated. The effect of temperature, initiator concentration, and monomer concentration on the conversion and the properties of the resulting polymers were studied. The optimum temperature in the investigated range (between −20°C and +20°C) was +5°C. The conversion is directly proportional to the concentration of both the initiator and the monomer. The molecular weight is inversely proportional to the initiator concentration and directly proportional to the monomer concentration. Under optimum conditions the molecular weight of the polymers is as high as 140,000. These results differ by an order from hitherto published data on the nonradical polymerization of vinyl chloride. The proportion of isotactic and syndiotactic structures resulting from the presence of tert‐butyllithium does not differ from that obtained by radical polymerization, but the occurrence of anomalous structures is reduced to a minimum. The stability of the macromolecules is higher. A mechanism of the polymerization is suggested.
Reaction of poly(vinyl alcohol) with formaldehyde and polymer stereoregularity. Model compounds
Authors: Shibatani Kyoichiro , Fujii Kiyoshi
Published: April 2003

The reaction of stereoisomers of pentane‐2, 4‐diol and heptane‐2, 4, 6‐triol with formaldehyde was investigated as a model for the formalization reaction of poly(vinyl alcohol) in order to determine effect of the stereochemical configuration of the polyol molecules on the reaction. The isotactic (meso) diol portion reacted with formaldehyde to give cis‐formal several times faster than did the syndiotactic (dl) diol portion to give trans‐formal at 30–80°C. In the reaction of heterotactic (meso‐dl) triol which provides both the isotactic and syndiotactic diol portions in a molecule, the proportion of trans‐formal in the total formal decreased as the reaction proceeded. This shows that the formation of cis‐formal is also favored thermodynamically to a greater extent, and hence the intramolecular migration of trans‐formal to cis‐formal did occur during the reaction. The rates of hydrolysis of formals of the diols were compared with those of the triols in order to see the effect of a hydroxyl group adjacent to the formal ring on the reaction. No appreciable rate difference was observed between the dimer and trimer models both in cis‐ and trans‐ formals. Therefore it was deduced from these results that the increase of the rate of hydrolysis of poly(vinyl formal) with the increase of hydroxyl groups along the polymer chain is a characteristic of macromolecules that is not observed in the low molecular weight models.
Copolymerization with depropagation. V. Copolymerization of α‐methylstyrene and methyl methacrylate between their ceiling temperatures
Authors: Izu M. , O'Driscoll K. F.
Published: April 2003

The variation of copolymer composition with monomer feed has been studied for the system α‐methylstyrene‐methyl methacrylate at 60, 114 and 147°C. The compositions predicted by the diad model of Part III of this series accurately describe the data.