bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of film thickness and inhibitor concentration on the sorption and thermal polymerization of acrylic acid in low‐density polyethylene
Authors: Sales Maria José Araújo , De Barros Glaucione Gomes 
Published: April 2003

AbstractWe investigated the effects of hydroquinone monomethyl ether concentration and film thickness upon the thermal polymerization of acrylic acid on low‐density polyethylene. The thermal polymerization of acrylic acid on low‐density polyethylene depended on the concentration of hydroquinone monomethyl ether inhibitor. It was a free‐radical reaction with initiation on the film surface and then proceeding to the bulk matrix. The process was not controlled by monomer diffusion for the range of film thickness of 90–200 μm. It became a diffusion‐controlled process at higher film thicknesses ( > 200 μm). A film layer of up to 100 μm was proposed as the limiting thickness for a diffusion‐free process. © 1993 John Wiley & Sons, Inc.
Aging and performance of structural film adhesives. IV. A modified epoxy with improved ambient temperature shelf life
Authors: Pearce P. J. , Ennis B. C. 
Published: April 2003

AbstractIt appears that improved latency in nitrile epoxy adhesives can be achieved by replacing the commonly used urea accelerator with one of much reduced solubility but similar chemical activity. A new, commercially available film adhesive claimed to possess a shelf life of 1 year at 22°C, excellent resistance to humidity prior to cure, and a service temperature range of −55 to 120°C has been examined. Areas studied included characterization, cure kinetics, adhesive performance, and shelf life. Its composition was found to be a variant of the 120°C curing nitrile—epoxy systems using a urea‐accelerated dicyandiamide cure. Two novel features were noted: the presence of bisphenol S and the urea 1,1'‐p‐phenylene‐bis(3,3‐dimethyl) urea. The relatively high shear strength found at elevated temperatures could be related to the adhesive's high Tg of 155°C resulting from the addition of bisphenol S and the improved room‐temperature latency was due to the ultralow solubility of the urea accelerator. Good durability was obtained from aluminum joints prepared using a simple silane pretreatment. Aging experiments indicated a shelf life of at least 3 months at 23°C under both dry and wet conditions, and it is predicted that adhesives of this type of composition would be stable for at least 1 year at normal domestic refrigeration temperatures of 5–10°C. © 1993 John Wiley & Sons, Inc.
Graft copolymers from modified ethylene–vinyl acetate (EVA) copolymer. I. Synthesis of poly(ethylene‐co‐vinyl acetate‐g‐styrene) using EVA modified by mercaptoacetic acid as chain transfer agent
Authors: Barbosa Ronilson V. , Soares Bluma G. , Gomes Ailton S. 
Published: April 2003

AbstractThe modification of the poly(ethylene‐co‐vinyl acetate) (EVA) by direct esterification of its ethylene—vinyl alcohol copolymer with mercaptoacetic acid was carried out. The amount of the mercaptan group was controlled to avoid gel formation during the graft polymerization with styrene by chain transfer. The chain transfer constant (Cs) of the SH groups and graft efficiency were measured. These graft copolymers were evaluated as a blend compatibilizer. © 1993 John Wiley & Sons, Inc.
Radiation‐grafting of acrylic acid onto ultrahigh molecular, high‐strength polyethylene fibers
Authors: Kaji Kanako , Abe Yoshinori , Murai Masaki , Nishioka Noboru , Kosai Kouichi 
Published: April 2003

AbstractRadiation‐induced grafting of acrylic acid onto ultrahigh molecular weight (UHMW) high‐strength polyethylene fibers to impart heat resistance and dyeability was undertaken. A preirradiation method was employed for grafting in an aqueous solution of acrylic acid containing a small amount of Mohr's salt as inhibitor. The grafting rate for UHMW high‐strength polyethylene fibers is one‐tenth of that for high‐density polyethylene fibers currently in use, and one‐hundredth, for high‐density polyethylene film. It has become clear that the preirradiation dose should be as low as 1 Mrad to keep the high strength of the starting fibers. The starting UHMW high‐strength polyethylene fiber begins to shrink remarkably at around 145°C, showing a maximum shrinkage of 90%, and then breaks at 154°C. When a 24% acrylic acid graft is converted to calcium salt, the grafted fiber retains the fiber form even at 300°C and gives only a maximum shrinkage of 11%. The less than 1% acrylic acid graft UHMW high‐strength polyethylene fibers and their calcium salt can be dyed to a deep shade with cationic dyes, whereas the starting fibers cannot be dyed with usual dyes including the cationic dye. © 1993 John Wiley & Sons, Inc.
Influence of gelling conditions on mechanical properties of simultaneous interpenetrating polymer networks from epoxy and bismaleimide resins
Authors: Iisaka Katsuyoshi 
Published: April 2003

AbstractSimultaneous interpenetrating polymer networks (SINs) were prepared from nadic methyl anhydride‐cured epoxy resin and bismaleimide (BMI) of which the composition ratios were, respectively, comprised of 3/1 (EM‐25 series) and 1/1 (EM‐50 series), under different gelling conditions for both resins. Dynamic mechanical and tensile properties were measured for these SINs. Turbidity was also measured to obtain some information regarding morphology. Although the rubbery modulus was constant irrespective of a gel‐time ratio (Gt) of the epoxide resin to that of BMI for the EM‐25 series, it increased with increasing Gt for the EM‐50 series. The glass transition temperature (Tg) was nearly constant at Gt < 1 and then decreased with increasing Gt at Gt > 1 for the EM‐25 series. On the other hand, Tg was nearly constant irrespective of Gt for the EM‐50 series, though the values of Tg at Gt < 1 were somewhat higher than those at Gt > 1. There was an appropriate value of Gt that gave better tensile strength (σb) or toughness evaluated by the area under a stress‐strain curve. The Tg and σb were found to be correlated to the turbidity of the SINs. The above mechanical behavior can be explained in terms of the molecular mixing and morphology that vary with a change in the relative polymerization rate of both the resins. © 1993 John Wiley & Sons, Inc.
Propylene polymerization with Mg(OEt)2/benzoyl chloride/TiCl4–triethyl aluminum/external donor catalyst systems
Authors: Lee Dong‐Ho , Jeong Young‐Tae , Soga Kazuo , Shiono Takeshi 
Published: April 2003

AbstractMg(OEt)2/benzoyl chloride (BC)/TiCl4 catalyst has been prepared by the chemical reaction method, and the chemical composition and X‐ray structure of the catalyst were studied. The effect of various conditions on catalyst activity and isospecificity were also examined. With 13C‐NMR analysis, it was found that aluminum carbinolate is formed during polymerization by reaction of triethyl aluminum cocatalyst with BC remaining in the prepared catalyst. The formed aluminum carbinolate acts as an additional donor to increase the isotactic index of polypropylene (PP). The morphology of the prepared catalyst and PP was also observed. © 1993 John Wiley & Sons, Inc.
Reactivity ratios and thermal and dielectric studies of n‐butyl methacrylate and methacrylamide copolymers
Authors: Srinivasulu B. , Rao P. Raghunath , Sundaram E. V. , Sathaiah G. , Sirdeshmukh Lalitha 
Published: April 2003

AbstractFree‐radical copolymerization of n‐butyl methacrylate (B) and methacrylamide (M) was carried out in the presence of 2,2'‐azobisisobutyronitrile (AIBN) in dimethyl formamide (DMF) at 60°C. The percentage composition of the copolymers was established by elemental analysis. The reactivity ratios as determined by the Finemann—Ross (F—R) and the Kelen–Tüdős (K—T) methods are r1 (B) = 2.75 ± 0.01, r2 (M) = 0.2 ± 0.01 and r1 = 2.70 ± 0.05, r2 = 0.19 ± 0.02, respectively. The copolymers were characterized by IR, 1H‐NMR, thermal, and dielectric studies. Glass transition temperature (Tg) values were determined by DSC. Dielectric studies were carried out to understand the segmental motions and the effect of composition on dielectric loss. © 1993 John Wiley & Sons, Inc.
Homo‐ and copolymers of furan–maleic anhydride and furan–dimethylacetylene dicarboxylate adducts via aqueous ring‐opening metathesis polymerization
Authors: Viswanathan Tito , Jethmalani Jagdish , Toland Alan 
Published: April 2003

AbstractHomo‐ and copolymers of the Diels‐Alder adduct of furan with maleic anhydride (F‐MA) and of furan with dimethylacetylene dicarboxylate (F‐DMAD) were synthesized by aqueous ring‐opening metathesis polymerization and characterized by IR, NMR, and DSC. Microstructural product analyses by 13C‐NMR indicated the copolymer composition to be 50 : 50 of each of the monomers when an equimolar mixture of RuCl3 and K2RuCl5, was used as the catalyst, with the cis‐form predominant for poly(F‐MA) and the trans‐form predominant for poly(F‐DMAD). On the practical side, the acidic and ester functionality of the copolymer would lend itself to be both blendable (and selectively extractable) with some already existing petroleum‐based acrylate polymers. © 1993 John Wiley & Sons, Inc.
The synthesis of polyethylene glycol (PEG) with different functional groups at each end. II. Synthesis of a series of monosubstituted PEG via polyvinyl alcohol (PVA) as support
Authors: Huang Junlian , Hu Youqian 
Published: April 2003

AbstractFive monosubstituted PEGs with different mol wt were synthesized and isolated using PVA as support. They were , respectively. The structure of these monosubstituted PEGs was characterized by IR, NMR, and element analysis. The effect of the reaction conditions on monosubstitution of PEGs was described. © 1993 John Wiley & Sons, Inc.
Linear polythioesters. XVIII. Products of interfacial polycondensation of bis(4‐mercaptophenyl)sulfide with aliphatic and aromatic acid dichlorides
Authors: Podkościelny Wawrzyniec , Rudź Wieslaw 
Published: April 2003

AbstractNew polythioesters were synthesized by interfacial polycondensation of bis(4‐mercaptophenyl)sulfide with aliphatic and isomeric phthaloyl chlorides. To determine the optimal conditions for polycondensation, we studied the influence of the following factors on the yield and reduced viscosity: type of organic solvent, concentration and molar ratio of monomers, ratio of aqueous to organic phase, concentration of hydrogen chloride acceptor (NaOH), acid chloride excess, rate of addition of acid chloride, the temperature of reaction, and the kind and the contribution of catalyst. A thorough examination was carried out for the polycondensation of dithiol, with sebacoyl and isophthaloyl chlorides chosen as a model systems. Polythioesters from aliphatic dichlorides were prepared under the optimal conditions used for sebacoyl chloride. For polythioesters from phthaloyl and terephthaloyl chlorides, the conditions were those used for isophthaloyl chloride. The structure of polythioesters was determined from infrared, X‐ray, and elementary analysis. Some physicochemical, thermal, mechanical, and electrical properties are reported. © 1993 John Wiley & Sons, Inc.
Surface properties and platelet adhesion characteristics of acrylic acid and allylamine plasma‐treated polyethylene
Authors: Ko Tze‐Man , Cooper Stuart L. 
Published: April 2003

AbstractAcidic oxygen‐containing and basic nitrogen‐containing functional groups were incorporated onto thin films formed by plasma polymerization of acrylic acid and allylamine in a lowpressure glow discharge. ESCA, ATR–FTIR spectroscopy, and static contact‐angle measurements confirmed the presence of these functional groups. Surface hydrophilicity of the acrylic acid plasma polymer decreased with time due to the diffusion of hydrophilic oxygencontaining functional groups away from the surface of the plasma‐treated polyethylene. In contrast, the hydrophilicity of the allylamine plasma polymer increased with time because of the extensive post‐plasma‐treatment oxidation with atmospheric oxygen. In assessing the blood compatibility of these two types of plasma polymer surfaces by platelet adhesion and spreading, the acidic acrylic acid plasma polymers showed an improvement in thromboresistance, but the basic allylamine plasma polymers were more thrombogenic than was the untreated low‐density polyethylene base material. © 1993 John Wiley & Sons, Inc.
Alginate polyelectrolyte ionotropic gels. VI. Novel synthesis of diketoalginates as biopolymer precursors
Authors: Hassan R. M. , Abd‐Alla M. A. , El‐Zohry M. F. 
Published: April 2003

AbstractSodium 2,3‐diketoalginate was quantitatively prepared by the oxidation of sodium alginate with potassium permanganate in alkaline solution at pH's > 12. The yield was 96.5%. The structure of the diketone was elucidated by microanalysis and spectroscopic data. It was found that the diketoalginate caused no gelation or precipitation with copper(II), nickel(II), or cobalt(II) divalent metal ions. © 1993 John Wiley & Sons, Inc.
Study of ketalization reaction of poly(vinyl alcohol) by ketones. VI. Reaction between poly(vinyl alcohol) and cyclic ketones and behavior of poly(vinyl ketal) in water
Authors: Nakamura Naofumi 
Published: April 2003

AbstractThe ketalization reaction of poly(vinyl alcohol) (PVAL) by cyclic ketones, with dimethyl sulfoxide (DMSO) as solvent, in the presence of an acidic catalyst in homogeneous system, was carried out. The synthesis of poly(vinyl ketals) was thus successfully performed, except for the case of poly(vinyl ketal) highly ketalized by cyclohexanone; these poly(vinyl ketals) with a ketalization degree of more than 60 mol % were insoluble in DMSO, and, thus, the reaction could not be carried out in a homogeneous system. The equilibrium constant at 40°C was ca. 0.50 in the case of cyclohexanone and ca. 0.35 in the case of cyclopentanone, some 10–50 times higher compared with the case of aliphatic ketones. Because the heat of reaction is 7.5 kcal/mol in all ketones, all ketalization reactions are considered to proceed by the same reaction mechanism. Films prepared from the poly(vinyl ketals) were soaked in water, and hydrolysis, degree of swell, and solubility were measured. The dissolution time of films is affected by the kind of the ketones, ketalization degree, and the pH of water, which reveals that deketalization reaction proceeds proportionally to the proton concentration. It is more difficult to dissolve poly(vinyl ketal) obtained by cyclohexanone than that by cyclopentanone. The rate of hydrolysis of poly(vinyl ketal) film obtained by cyclohexanone is nearly equal to that by methyl butyl ketone, and that by cyclopentanone is nearly equal to that by methyl propyl ketone. The contact angle, surface free energy, moisture regain, and water permeability of poly(vinyl ketal) films were measured. All the results show that poly(vinyl ketal) obtained from cyclohexanone is a more hydrophobic polymer than that from cyclopentanone. The hydrophobicity seems to depend upon the kind of the original ketones and the flexibility of the ring. © 1993 John Wiley & Sons, Inc.
Photopolymerization of methyl methacrylate using benzoin isopropyl ether as photoinitiator: Effect of thiophenol compounds
Authors: Wang W. , Hu G. H. 
Published: April 2003

AbstractEffects of a series of thiophenols RArSH with substituting groups R in the para‐position and 2‐mercaptobenzoic acid on the kinetics of polymerization of methyl methacrylate (MMA) photoinitiated by benzoin isopropyl ether (BIPE) were investigated using an autorecording dilatometer. Thiophenols were found to have a dual effect on polymerization: reducing induction time and accelerating rate of polymerization. A mechanism was proposed suggesting that this increased rate of polymerization and reduced induction time with addition of a thiophenol is due to the fact that, instead of consuming radicals, the dissolved oxygen in the MMA/BIPE system can be converted into active radicals through effective photooxidation of the thiophenol. Although the maximum increase in rate of polymerization is of a minor difference between various thiophenol compounds, reduction in induction time is strongly dependent on the nature of substituting groups in the following order: CH3 > CH(CH3)2 > OCH3 or Cl > H. 2‐Mercaptobenzoic acid, on the other hand, increases induction time and decreases rate of polymerization. © 1993 John Wiley & Sons, Inc.
SEC–viscometer detector systems. II. Resolution correction and determination of interdetector volume
Authors: Cheung P. , Lew R. , Balke S. T. , Mourey T. H. 
Published: April 2003

AbstractThe closely related topics of resolution correction and the determination of interdetector volume were examined. In determining the interdetector volume (δ) by searching to superimpose two types of intrinsic viscosity calibration curve (one from narrow standards and one from a broad standard), the underlying equation based upon symmetrical axial dispersion theory was derived. This equation combined with experimental results showed that the local intrinsic viscosity value is very similarly affected by interdetector volume and by band spreading. The result supported the idea of using an effective δ to effect an axial dispersion correction to local intrinsic viscosity data. However, it also increased the difficulty of finding both δ and standard deviation (δ) simultaneously by numerical search. Furthermore, attempts to apply the method to the chromatograms of narrow standards showed inadequate superposition. Following calculation of skewing factors, the superposition problems were attributed to skewing of the chromatograms of the monodisperse polymer standards used. © 1993 John Wiley & Sons, Inc.
Thermal and morphological characterization of binary blends of fractions of 1‐octene LLDPE
Authors: Defoor F. , Groeninckx G. , Reynaers H. , Schouterden P. , Van Der Heijden B. 
Published: April 2003

AbstractAn ethylene/1‐octene linear low‐density polyethylene (LLDPE B) has been fractionated with respect to the short‐chain branching content of the molecules, using the preparative temperature‐rising elution fractionation (PTREF) technique. The LLDPE B studied, which is characterized by a high degree of heterogeneity on the level of the molecular weight and the comonomer content, was fractionated into six fractions having a more homogeneous intermolecular comonomer distribution. As a result of the differences in the chain microstructure of the fractions, a strong change in the thermal characteristics such as onset temperature of crystallization from the melt and melting temperature has been found. The morphology of the fractions, i.e., spherulitic texture and semicrystalline lamellar ordering, also strongly depends on the chain microstructure. In an attempt to elucidate the mutual influence of molecules having a different chain microstructure, as occurring within the unfractionated copolymer, blends of preparative TREF fractions were prepared and investigated with respect to their thermal behavior and morphology. © 1993 John Wiley & Sons, Inc.
Natural and artificial weathering of low‐density polyethylene (LDPE): Calorimetric analysis
Authors: Sebaa M. , Servens C. , Pouyet J. 
Published: April 2003

AbstractStudies of the thermal and photodegradation of two commercial polymers, stabilized and unstabilized low‐density polyethylene, show the effects of weathering on differential scanning calorimetry (DSC) curves. The shape and the size of the melting peak vary significantly in thermal aging and in accelerated photoirradiation, but no change was observed in natural weathering, implying that the crystallinity remains steady in outdoor exposures. The melting temperatures remain steady for all exposure tests. The fall of mechanical properties and the evolution of chemical structure, followed by IR spectroscopy results, especially near the carbonyl regions, were also observed. The resistance to UV light irradiation as probed by deformation at break was superior in stabilized LDPE compared to unstabilized LDPE. Simple correlations observed between the fall of mechanical properties, the rate of oxidation, and morphology. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of cyano‐substituted maleamic acids and maleimides and their polymerization to thermally stable laminating resins
Authors: Mikroyannidis John A. 
Published: April 2003

AbstractA novel class of cyano‐substituted maleimides were prepared and polymerized. Particularly, 4‐aminobenzonitrile reacted with maleic or nadic anhydride to yield the amic acid, which was then cyclodehydrated to the corresponding maleimide or nadimide. In addition, the monomaleamic acids prepared from an aromatic diamine reacted with 4‐cyanobenzaldehyde to afford maleamic acids that were cyclodehydrated to maleimides. All maleimides and nadimide as well as their intermediate amic acids were characterized by IR and 1H‐NMR spectroscopy. The curing behavior of polymer precursors was investigated by DTA. Upon curing at 240°C for 15 h, network polymers were obtained both by cross‐linking through the maleimido olefinic bonds and the trimerization reaction of the cyano groups. They were stable up to 330–310°C in N2 or air and afforded anaerobic char yield of 60–40% at 800°C. © 1993 John Wiley & Sons, Inc.
Anionic copolymers of octanelactam with laurolactam (nylon 8/12 copolymers). VII. Study of diffusion and permeation of gases in undrawn and uniaxially drawn (conditioned at different relative humidities) polyamide films
Authors: Arvanitoyannis Ioannis , Blanshard John M. V. 
Published: April 2003

AbstractThe permeability coefficient of a wide range (0/100–100/0 octanelactam/laurolactam [OL/LL] mol/mol) of novel copolyamides (nylon 8/nylon 12) was determined and related to the diffusion rate over a range of temperatures: Tg–30 to Tg + 40°C. An inflection in the plot of permeability vs. 1/T (K) provided an indirect indication of glass transition value and agreed satisfactory with DSC and DMTA measurements. Both uniaxially drawn and undrawn membranes were evaluated and the permeability values were correlated with the % crystallinity. The reduction in solubility, diffusivity, and permeability with increasing draw ratio was attributed to a substantial increase in % crystallinity. Finally, the effect of absorbed water on gas permeability of polyamide films was examined. In most homopolyamides and copolyamides, the higher the water absorption of films the higher the permeability values. © 1993 John Wiley & Sons, Inc.
NMR and sedimentation studies of a polymeric steric stabilizer for alumina
Authors: Parker A. A. , Armstrong G. H. , Hedrick D. P. 
Published: April 2003

AbstractThe sedimentation behavior of alumina powder has been studied in the presence of poly‐vinylpyrrolidone (PVP) and poly(vinylpyrrolidone‐co‐vinyl acetate) (PVP/VA) in both thermodynamically “good” and “poor” solvents for the PVP homopolymer. PVP/VA provides higher sediment densities than does its PVP homopolymer counterpart. Solutionstate 13C‐T1 spin‐lattice relaxation measurements were made on analogous mixtures both with and without alumina powder. The NMR results suggest that the PVP/VA copolymer is anchored to the alumina powder surface by means of VA moieties, whereas the PVP moieties extend into the continuous phase of the slurry medium. Thus, the higher settling densities that are observed in the presence of PVP/VA can be attributed to a steric stabilization mechanism. © 1993 John Wiley & Sons, Inc.