bluuebunny/crossref_metadata_2025_split huggingface dataset:
γ‐radiation‐initiated emulsion polymerization of n‐butyl acrylate and of methyl methacrylate
Authors: O'Neill Thomas , Hoigné Jürg 
Published: April 2003

AbstractWe have investigated the γ‐radiation‐initiated polymerization of n‐butyl acrylate (BA) and of methyl methacrylate (MMA) in aqueous emulsions stabilized with sodium lauryl sulfate (SLS). The reaction rate, as measured by a nonabsolute thermocouple technique, varies as the square root of emulsifier concentration for both monomers. In the case of BA, the dose rate exponent of the reaction rate is 0.7 ± 0.3, whereas the corresponding value for MMA is approximately 0.4. The overall activation energy of the BA polymerization is close to zero, whereas for MMA a value of 4.8 ± 2.1 kcal/mole has been found. The poly(butyl acrylate) molecular weight is effectively independent of soap concentration and of dose rate but decreases as the reaction temperature is increased in the range 30–70°C. The general conclusion drawn from this work is that these radiation‐induced emulsion polymerizations differ little from conventionally initiated systems insofar as the reaction kinetics are concerned. Poly(butyl acrylate‐g‐methyl methacrylate) copolymers have been prepared by a direct irradiation method involving a poly(butyl acrylate) prepolymer seed latex. Some physical properties of this material have been examined.
Polymers of tertiary amines
Authors: Henrici‐Olivé G. , Olivé S. 
Published: April 2003

AbstractPolymers of tertiary amines and their hydrochlorides of molecular weights in the range 300–2000 have been prepared, starting from trans‐1,4‐dichlorobutene‐2, and primary amines. The polymers present interesting solubility properties. Variation of the reaction conditions leads to crosslinked insoluble polymers. Reaction of the soluble tertiary amine polymers with organic acid dichlorides leads to polymers of tertiary amine–amides, a new type of polymer.
Solute absorption into molten polystyrene
Authors: Covitz F. H. , King J. W. 
Published: April 2003

AbstractThe equilibrium volatilities at near infinite dilution of various solutes absorbed in molten polystyrene have been determined by a gas chromatographic technique. This method is much more rapid, although, with the present apparatus, probably less accurate than conventional static techniques. The primary parameters obtained from measurements of retention volumes are the Henry's law constants, from which are derived the weight and volume fraction activity coefficients, the Flory‐Huggins interaction parameters, and the heats of dilution and solution.Of the solutes investigated, 2‐butanone (MEK) was the least, and benzene the most compatible (highest and lowest volume fraction activity coefficients, respectively) with molten polystyrene. A small, but definite, variation of the activity coefficients with polystyrene molecular weight was observed.
The use of organotin compounds in the thermal stabilization of poly(vinyl chloride). Part III. Reactions of dialkyltin mercaptides, thioglycollates, and carboxylates with chlorohydrocarbons
Authors: Ayrey G. , Poller R. C. , Siddiqui I. H. 
Published: April 2003

AbstractReactions of dialkyltin mercaptides, thioglycollates, and carboxylates with the poly‐(vinyl chloride) model compounds tert‐butyl chloride and 3‐chlorobut‐1‐ene have been studied. At 180° the tertiary and allylic chlorine atoms in the model compounds undergo exchange reactions with the SR, SCH2COOR, and OCOR groups attached to tin. In the case of 3‐chlorobut‐1‐ene, the exchange reactions are accompanied by allylic rearrangements. The relevance of these results to the stabilization of poly(vinyl chloride) is discussed.
Heterogeneous grafting of polypropylene and physical properties of graft blends
Authors: Jabloner H. , Mumma R. H. 
Published: April 2003

AbstractPolypropylene powder, as formed by typical Ziegler catalysts, can conveniently be hydroperoxidized in aqueous slurry. A cationic surfactant and potassium persulfate are used to achieve wetting and initiate oxidation. It is proposed that specific reaction between the quaternary ammonium cations and persulfate anion generates a water‐insoluble persulfate which decomposes to yield a hydrophobic radical species which initiates oxidation. Graft copolymers were prepared by using this polypropylene hydroperoxide, a redox catalyst, and either dimethylaminoethyl methacrylate or n‐butyl acrylate. These graft copolymers, dispersed in polypropylene, form two‐phase systems in the solid state. Under synthesis conditions which are believed to yield long side chains, the dispersed, more polar polymer was found in larger domains than observed with shorter side chains. Polypropylene spherulites were also distorted, although per cent crystallinity of the continuous polypropylene phase was hardly affected by the presence of graft. Mixtures of poly(propylene‐g‐butyl acrylate) and polypropylene are rather extensible and of low modulus. Low temperature tensile impact values are only slightly higher than for pure polypropylene. Addition of poly(butyl acrylate) to these blends increases both the low‐speed modulud and high‐speed tensile impact relative to the two component blends.
Optically active hydrocarbon polymers with aromatic side chains. II. Poly‐(S)‐p‐sec‐butylstyrene
Authors: Ciardelli F. , Pieroni O. , Carlini C. , Menicagli C. 
Published: April 2003

AbstractThe synthesis of optically active p‐sec‐butylstyrene (I) has been carried out starting with (S)‐2‐phenylbutane (II) having optical purity 88–91%. The optical purity of I thus obtained was found to be 73–75%. The polymerization of I with stereospecific coordinated anionic catalysts gave amorphous polymers, as in the case of many other p‐substituted styrene derivatives. The fractions obtained from these polymers have very similar rotatory power at 589 nm which is practically equal to that of polymer of I obtained by nonstereospecific radical initiator and of low molecular weight structural models. Accordingly the 1Lb electronic transition of the aromatic chromophore shows a very low rotatory strength in all samples examined. This result is related to the lack in solution of conformations with a predominant single chirality of the main chain of the macromolecules derived from I.
Radical terpolymerization of sulfur dioxide, styrene, and methyl methacrylate
Authors: Matsuda Minoru , Iino Masashi , Numata Shun‐Ichi 
Published: April 2003

AbstractThe radical terpolymerization of sulfur dioxide, styrene, and methyl methacrylate in o‐dichlorobenzene with 2,2′‐azobisisobutyronitrile was carried out in order to clarify the propagation mechanism of the radical copolymerization of sulfur dioxide and styrene, especially as a function of total concentration of sulfur dioxide and styrene. From the analysis of the trigonal composition diagrams it has been definitely shown that the radical copolymerization of sulfur dioxide and styrene proceeds by the propagation of two monomers, but the usual type of copolymerization mechanism, explicable in terms of the Lewis‐Mayo equation, is not applicable to this copolymerization. The participation in the propagation of a monomer charge‐transfer complex consisting of sulfur dioxide and styrene was also ruled out.
Radical copolymerization of sulfur dioxide and chloroprene
Authors: Matsuda Minoru , Hara Yoshinori 
Published: April 2003

AbstractThe radical copolymerization of sulfur dioxide and chloroprene (CP) in benzene was carried out, especially as a function of the total monomer concentration ([SO2] + [CP]). The composition of chloroprene polysulfones varies mainly with total monomer concentration and with polymerization temperature, but depends very slightly on feed composition. The microstructure of chloroprene units in chloroprene polysulfone was such that the trans‐1,4 unit was predominantly over the cis‐1,4 unit. Thus it would seem possible to rule out both radical copolymerization mechanisms, i.e., propagation of separate monomers as explained by the Lewis‐Mayo equation, and propagation processes involving a monomer charge‐transfer complex.
Use of gel‐permeation chromatography in the determination of the composition of two‐polymer mixtures
Authors: Menin Jean‐Pierre , Roux René 
Published: April 2003

AbstractThe possibility of evaluating with acceptable accuracy the composition of a two‐polymer mixture which is well separated by GPC, was studied by using mixtures of high molecular weight polybutadiene (M̄w = 4.5 × 105) and low molecular weight polyiso‐butylene (M̄n in the range of 103). It was concluded that a satisfactory evaluation of the composition of a polymer mixture can be achieved, provided that the variations of the refractive index with the molecular weight are taken into account for the low molecular weight polymer (the polyisobutylene).
Disposition of D‐glucopyranosyl units on the surfaces of crystalline elementary fibrils of cotton cellulose
Authors: Rowland Stanley P. , Roberts Earl J. 
Published: April 2003

AbstractThe results from two different chemical approaches to study the disposition of D‐glucopyranosyl segments of the cellulose chains on the surfaces of microstructural units accessible to chemical reagents in cotton cellulose are compared, correlated, and rationalized. These studies provide the basis for a suggested disposition of D‐glucopyranosyl units in the crystalline surfaces of elementary fibrils, for a proposed arrangement of hydrogen bonds on these surfaces, and for estimates of the size of the elementary fibrils.
Synthesis and characterization of some new polymeric peroxycarbamates
Authors: Baysal B. M. , Short W. T. , Tobolsky A. V. 
Published: April 2003

AbstractThe synthesis and characterization of several polymeric peroxycarbamates prepared by successive reaction of poly(ethylene oxides), first, with diisocyanates, and then with hydroperoxides, are described in detail for bis(2,5‐dimethyl‐2‐hydroperoxyhexane peroxycarbamate) polyethers, the chain‐extended analogs of these peroxycarbamyl polyethers and for bis(α‐cumyl peroxycarbamate) polyether. The polymerization of styrene with this last initiator was studied at 60, 80, and 100°C. Both low‐ and high‐conversion polymerizations were studied. The relationship between the rates of initiation and the inverse degree of polymerization was determined.
Polymers of C1C4 paraffin hydrocarbons from an RF discharge: Characterization and reactivity
Authors: Wendel C. T. , Wiley M. H. 
Published: April 2003

AbstractThe polymers deposited from mixtures of argon and the vapors of methane, ethane, propane, and n‐butane subjected to excitation in a 30‐MHz discharge have been analyzed by infrared absorption techniques and for elemental composition. The polymers show unsaturation, crosslinking, and branching. The stability of the polymers to atmospheric oxidation is discussed.
Telechelic diene prepolymers. IV: Anionic polymerization studies
Authors: Reed Samuel F. 
Published: April 2003

AbstractThe preparation and characterization of functionally terminated polybutadienes by an anionic polymerization technique is described. Prepolymers possessing hydroxyl end‐groups were synthesized via vacuum‐line methods. Characterization was completed through endgroup, functionality, molecular weight, molecular weight distribution, and microstructural analyses. Emphasis was placed on the reproducibility in the properties of the prepolymers, particularly in their functionality.
Sulfur‐containing polymers. II. Preparation and properties of polycarbamoylsulfenamides
Authors: Kobayashi Norio , Fujisawa Tamotsu 
Published: April 2003

AbstractPolycarbamoylsulfenamides have been prepared by interfacial and solution polycondensation of chlorocarbonylsulfenyl chloride with diamines. In preparing the polycarbamoylsulfenamides, the following types of diamines were used: primary aliphatic diamines, a mixed primary‐secondary aliphatic diamine, primary aromatic diamines, and secondary aromatic diamines. The properties of the resulting polymers depended primarily on the kind of diamines used. Transparent, tough films were obtained from the polymer based on N,N′‐dimethyl‐4,4′‐diaminodiphenylmethane. The photochemical decomposition of the polymers has been studied.
Stereochemistry of alternating isobutene–maleic anhydride, isobutene–dimethyl fumarate, and isobutene–dimethyl maleate copolymers
Authors: Bacskai R. , Lindeman L. P. , Rabenstein D. L. 
Published: April 2003

AbstractThe stereochemical composition of the free radical alternating isobutene–maleic anhydride (IB/MA), isobutene–dimethyl fumarate (IB/DMF), and isobutene–dimethyl maleate (IB/DMM) copolymers was investigated by proton magnetic resonance. In contrast to the singlet gem‐dimethyl resonance found in polyisobutene or in the alternating isobutene/acrylonitrile copolymer, the gem‐dimethyl resonance of IB/MA, hydrolyzed IB/MA, and esterified IB/MA is a quadruplet with peaks of approximately equal intensity. The multiplicity of the spectra is consistent with the presence of equal amounts of threo‐di‐isotactic and threo‐di‐syndiotactic triads, disproving previous claims that such copolymers are predominantly threo‐di‐isotactic. The spectrum of the analogous IB/DMF indicates that the copolymer is composed entirely of erythro‐di‐ isotactic and erythro‐di‐syndiotactic triads. This result is consistent with the exclusive trans opening of the dimethyl fumarate double bond and provides the first example for the stereospecific double bond opening of a noncyclic monomer in free radical polymerization. In contrast, the spectrum of IB/DMM shows that the dimethyl maleate double bond opens approximately 93% cis and 7% trans during copolymerization. Since the stereochemical composition of IB/DMF and IB/DMM is not the same, it is concluded that the radicals formed from dimethyl maleate and/or dimethyl fumarate do not equilibrate freely among all the possible configurations before isobutene addition.
Photodegradable polyamides
Authors: Takahashi Hiroshi , Sakuragi Masako , Hasegawa Masaki , Takahashi Hiroshi 
Published: April 2003

AbstractUnique photodegradable polyamides have been prepared by solution polymerization of diphenyl α‐truxillate or δ‐truxinate with hexamethylene or nonamethylenediamine, followed by melt polymerization. Photochemical properties of resulted polyamides were studied spectroscopically and are discussed in terms of photoreversibility and monomeric derivatives for comparison. Solution viscosity of the polymer was decreased by irradiation with a high‐pressure mercury lamp. The polymers from α‐truxillic acid depolymerize by the action of monochromatic light of 224 mμ to give rise to cinnamyl groups faster than those from δ‐truxinic acid. On the photodegradation of polyalkylene‐δ‐truxinamide, two types of scission of cyclobutane were found: symmetrical scission, giving rise to two cinnamyl groups, and a symmetrical scission, giving rise to one trans‐stilbene and one fumaramide linkage. The intense absorption peak due to cinnamyl groups at 272 mμ of partially photodepolymerized films diminished by the action of 304 mμ light; this can be accounted for by the recombination of cinnamyl groups into cyclobutane ring and some unidentified crosslinking reactions. The photochemical behavior of cyclobutane in the polyamides studied proved to be consistent with that of monomeric derivatives reported previously. The study on thermal properties of the polymers by DTA and TGA revealed that this type of polyamide is quite stable as high as 350°C unless significant steric effects are involved.
Molecular weight distributions in radiation‐induced polymerization. IV. A comprehensive kinetic scheme for polymerization in the liquid state
Authors: Westlake John F. , Huang Robert Y. 
Published: April 2003

AbstractA comprehensive kinetic scheme is proposed which takes into consideration γ‐ray‐initiated polymerization via free radical, cationic, or radical‐cationic species, or their combinations, and the relative contribution of each depending upon experimental conditions. From this kinetic model, equations describing the kinetics of polymerization and the resulting molecular weight distributions have been derived. The resulting expressions are complex in nature, particularly for the case where a combination of mechanisms is involved. In view of this, a general approach to the problem of generating theoretical molecular weight distributions based on the application of high speed digital computers has been presented. The proposed technique is particularly powerful since no simplifying assumptions or mathematical approximations are required in order to obtain the molecular weight distribution.
Molecular weight distributions in radiation‐induced polymerization. V. A simultaneous kinetic and molecular weight distribution analysis of the liquid‐state polymerization of styrene
Authors: Westlake John F. , Huang Robert Y. 
Published: April 2003

AbstractThe γ‐ray initiated polymerization of styrene in the liquid state was investigated over the temperature range 0 to −29°C at constant dose rate. The kinetics and molecular weight distributions were studied for samples prepared by standard techniques and samples subjected to exhaustive drying to remove residual water. In the former case, the rates of reaction were comparable to those for purely free radical polymerization, however, the resulting molecular weight distributions were distinctly bimodal, indicating an additional contribution from the cationic mechanism. On the other hand, the rates of polymerization for rigorously dried samples were 2 to 3 orders of magnitude greater than accepted free‐radical values, and the molecular weight distributions were unimodal in nature. The experimental results were compared with theoretical kinetic data and molecular weight distribution data generated from a kinetic scheme taking into consideration polymerization via free‐radical, cationic, and radical‐cationic species, resulting in the evaluation of a number of quantities of interest. Substitution of determined values for the rate constants and G values results in good agreement between theoretically generated and experimentally determined kinetic data and molecular weight distribution data over the range of experimental conditions studied.
Radical polymerization of vinyl acetate with primary radical termination
Authors: Ito Katsukiyo 
Published: April 2003

AbstractVinyl acetate was polymerized at high initiation rate with 2,2′‐azobis(2,4‐dimethyl valeronitrile) as initiator at 50°C. In this polymerization, the power dependence of polymerization rate on the initiation rate is smaller than at lower concentration of monomer. This dependence was kinetically analyzed at each given concentration of monomer. Average degree of polymerization of polymer formed depends on the concentration of initiator. This dependence was explained by considering chain and primary radical terminations and transfer to monomer of polymer radical, and the initiator efficiency (=0.503) was deduced. It was found that the chain termination is inversely proportional to solvent viscosity, but the primary radical termination is not inversely proportional to solvent viscosity. Further, the value of the primary radical termination rate constant (=1.4 × 109l./mole‐sec) was estimated.
Thermal degradation of polyurethanes based on xylylene diisocyanates
Authors: Rumao L. P. , Frisch K. C. 
Published: April 2003

AbstractPolyurethanes derived from xylylene diisocyanates and trans‐1,4‐cyclohexanedimethanol were thermally degraded by using the techniques of thermogravimetry and pyrolysis at atmospheric pressure. Quantitative determination of the pyrolysis products such as CO2, diamine, olefin, and starting diol showed that these polyurethanes follow the typical mechanism of degradation via dissociation into starting diol and diisocyanate. Kinetic parameters for the overall degradation reaction were determined using four different methods. The results showed the influence of the experimental technique used when making a comparison of the thermal stability of polymers, as determined by the kinetic parameters of the degradation reactions.
Dye‐sensitized photopolymerization of vinyl monomers in the presence of ascorbic acid–sodium hydrogen orthophosphate complex
Authors: Nagabhushanam T. , Santappa M. 
Published: April 2003

AbstractThe kinetics of photopolymerization of vinyl monomers (methyl methacrylate, methylacrylate, and acrylonitrile) sensitized by the dyes acridine orange, dahlia violet, rose bengal and Pyronine G have been studied systematically. Systems containing dye, reducing agent, and monomer were irradiated with light of wavelengths 365 mμ, 546 mμ, and 405 mμ. The induction period was kept to a minimum by suitable experimental conditions. All experiments were conducted under deaerated conditions. The complex, AA–B, formed between ascorbic acid and sodium hydrogen orthophosphate (of the buffer) and reported earlier from our laboratory, played an important role in the production of the free radicals. The course of the polymerization reaction was followed by the measurements of rate of monomer disappearance −d[M]/dt (gravimetrically), rate of dye disappearance −d[D]/dt (spectrophotometrically), and the chainlengths n, of the polymer formed (viscometrically); light intensity, light wavelength, and concentrations of the dye, reducing agent, and monomer were the various variables for these measurements. A tentative scheme based on the excitation of the dye in the primary photochemical act and the interaction of the excited dye with the complex AA–B in the dark resulting in radicals (from ascorbic acid) which initiate vinyl polymerization is proposed, and the experimental results are found to conform to such a scheme. The values of various ratios of rate constants such as kp/kt½, kr/k7, ki/k6 were calculated and are discussed.
Polymerization by oxidative coupling. IV.. Synthesis and properties of poly(2‐methyl‐6‐phenylphenylene ether)
Authors: White D. M. , Klopfer H. J. 
Published: April 2003

AbstractCopper‐amine catalyst systems which polymerize 2‐methyl‐6‐phenylphenol to high molecular weight polymer are described. With CuCl and N,N,N ′,N′‐tetramethyl‐1,3‐butanediamine (TMBD), an intrinsic viscosity of 1.56 dl/g was obtained. Faster rates of polymerization resulted with a CuBr‐TMBD catalyst. Catalysts from other tertiary amines and mixtures of tertiary amines also produced high polymer. Pyridine and diethylamine catalyst were less active. Samples of polymer were isolated at different stages of the polymerization. Measurements of viscosity, osmotic pressure, light scattering, gel permeation, hydroxyl groups, nitrogen content, and chemical reactivity were made on the samples. Below a molecular weight value of M̄n 60,000, M̄n/M̄w was 2.0. At higher molecular weights, there was a broadening in molecular weight distribution. No major change in the molar concentration of the “;head” endgroups with increasing molecular weight was detected by infrared analysis. However, nitrogen analyses, chemical reactivity studies, and the M̄n/M̄w ratio suggested the chemical nature of the “head” end had changed. The relationships between intrinsic viscosity in chloroform at 25°C and M̄n and M̄w for unfractionated polymer samples are log [η] = −4.26 + 0.84 log M̄n and log [η] = −3.86 + 0.70 log M̄w.