bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiation‐induced graft copolymerization of methacrylic acid onto polypropylene fibers. II. Effect of solvents
Authors: Mukherjee A. K. , Gupta B. D. 
Published: April 2003

AbstractGraft copolymerization of methacrylic acid onto polypropylene fibers by simultaneous‐gamma ray irradiation technique was carried out. The effect of various solvents on grafting was studied. The results have been presented in terms of swelling behavior of polypropylene fiber and the extent of homopolymerization. An accelerative effect upon the rate of grafting was observed when benzene was partly replaced by methanol. At the dose rate of 24 rad/s and monomer concentration of 3 mol/L, a maximum in the rate of grafting was observed with 40% methanol fraction in the benzene–methanol mixture. However, a further increase in the methanol fraction in the solvent mixture resulted in a sharp decrease in the rate of grafting. No grafting was observed in pure methanol. This behavior has been explained in terms of the inhibitory action of methanol for polymerization of methacrylic acid and the extent of swelling of polypropylene fiber in various compositions of benzene–methanol mixture.
Theory of tack of pressure sensitive adhesive. I
Authors: Mizumachi Hiroshi 
Published: April 2003

AbstractIf the tack of a pressure‐sensitive adhesive is closely related to the rolling motion of a ball on the material, it is more scientific to express tack in terms of the rolling friction coefficient, which depends on the physical properties of the materials, and not on any trivial conditions of measurements. It is shown that the rolling friction coefficient of a pressure‐sensitive adhesive can experimentally be determined from the pulling cylinder method much more easily than the rolling ball method and that we can theoretically calculate the rolling friction coefficient by making some assumptions, concerning deformation and failure of a pressure‐sensitive adhesive.
Aromatic ionomer membranes. I. Physical and mechanical properties
Authors: Besso E. , Legras R. , Eisenberg A. , Gupta R. , Harris F. W. , Steck A. E. , Yeager H. L. 
Published: April 2003

AbstractThe physical properties of a new class of ionomers comprising a semirigid polyphenylene ether backbone were investigated. The material was studied principally in the form of films of ca. 150 μm micrometers in thickness. The study focused on material of 600 equivalent weight. Torsion pendulum results showed a significant increase in the glass transition temperature of the ionomer relative to that of its ester precursor but gave no evidence of ionic clustering. Stress–strain studies performed both in water and in 20% KOH solution at 80°C indicated that the mechanical properties of the material remain stable under these conditions. Differential scanning calorimetry was used to investigate both the high temperature behavior and the water uptake of the ionomer films. The behavior of this ionomer at high temperature and in an alkaline solution is of particular interest in view of the possible use of these films as separators in an alkaline electrolysis cell.
Effects of various factors on the formation of high molecular weight polyamic acid
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei 
Published: April 2003

AbstractThe reaction of pyromellitic dianhydride (PMDA) and aromatic diamine in an aprotic solvent such as dimethylacetamide (DMAc) gives a solution of poly(amic acid). The effects of certain variables on the polymerization and some additives on the stability and imidization of the poly(amic acid)s were studied. It was found that the addition of PMDA portionwise to the solution of diamine always keeps the excess diamine in solution and enables one to obtain the highest molecular weight of poly(amic acid). When the addition process was reversed, either by the change or dehydration of solvent, a high molecular weight was not attained. The inevitable water in the solvent or the reaction medium is the major factor, and the more the water content in the solvent or the reaction medium, the larger is the probability of destruction of PMDA during the reaction and hence low molecular weight is obtained. If very pure monomers were used in the polymerization, the 1:1 of molar ratio is the optimum value. Excess diamine or dianhydride results in the exchange reaction with poly(amic acid) and causes a rapid degradation of polymer chain. This exchange reaction was proved by NMR measurements. The presence of electrophilic agents or the nucleophilic agents containing active protons in the poly(amic acid) solution promotes the decomposition of polymer and causes the brittleness of polyimide film in the curing process. Using acetic anhydride (A) to convert the poly(amic acid) to polyimide, pyridine (P) can protect the polymer chain from the nucleophilic attack by the anhydride. The mixture with proper ratio of A/P (1/1–15/1) can be used as good dehydrating agents.Meanwhile, according to the results to the results of experiments, we suggested the probable reaction mechanisms about how the water, amine, and anhydride destroy the polyamic acid chains.
The synthesis and properties of tetrafunctional epoxy resins
Authors: Liu Wen‐Liang , Pearce Eli M. , Kwei T. K. 
Published: April 2003

AbstractN,N,N′,N′‐tetraglycidyl‐4,4′‐diaminodiphenylalkane epoxy resins with alkyl substituents on the methylene carbon were synthesized and characterized. The thermal and dynamic mechanical properties of these resins when cured with diaminodiphenylsulfone were compared with those of the cured unsubstituted epoxy resin. Although the resins have similar structures, the cured resin from the unsubstituted epoxy has the higher polymer decomposition temperature and glass transition temperature. The substituted epoxy resins have higher dynamic Young's moduli and loss moduli.
Effect of coagulation medium on properties of sulfonated polyvinylidene fluoride membranes
Authors: Bottino A. , Capannelli G. , Munari S. 
Published: April 2003

AbstractThe performance and the structure of sulfonated polyvinylidene fluoride membranes prepared in different coagulation media were investigated. Several pure organic compounds and mixtures of some of them with water were used as coagulation media. The membrane were tested in an ultrafiltration laboratory unit with dextran aqueous solutions. The overall structure of the membranes was examined with the aid of the scanning electron microscope. The effect of temperature of the coagulation medium on the properties of the membranes were also investigated.
Coordination behavior of cyanide ion to hemin uncomplexed and complexed with several synthetic polymer ligands
Authors: Kokufuta Etsuo , Watanabe Hiroshi , Saito Kiyoshi , Nakamura Isei 
Published: April 2003

AbstractHemin (H) (ferri–protoporphyrin IX chloride) was complexed in aqueous media with the following polymer ligands; poly(L‐lysine), poly(L‐histidine), branched polyethyleneimine, and two copolymers of 1‐vinyl‐2‐pyrrolidone with 1‐vinylimidazole and with 1‐vinyl‐2‐methylimidazole. The resulting water‐soluble complexes were either the five‐ or six‐coordinate hemichromes, respectively, which coordinated one or two ligand units in polymer to ferri—protoporphyrin IX (FP). The coordination behavior of cyanide ion to the hemichromes and also to H was investigated by means of spectroscopic titration method. It was found that one cyanide ion binds not only to the five‐coordinate hemichromes, but also to the six‐coordinate ones by the ligand exchange reaction with the cyanide ion, whereas two cyanide ions coordinate to H, which is free from polymer ligand able to occupy the coordination site(s) of FP. Morever, the degree of saturation of the iron(III) in FP with cyanide ion for all the hemichromes was found to be much larger than that for H. These results indicate that the ability of FP to coordinate cyanide ion is closely associated with whether one coordination site of FP is occupied by polymer ligand or not.
Radiation‐Induced graft copolymerization of methacrylic acid onto polypropylene fibers. V. Mechanical properties
Authors: Mukherjee A. K. , Gupta B. D. 
Published: April 2003

AbstractMechanical properties of polypropylene‐g‐poly(methacrylic acid) fibers, prepared by graft copolymerization of methacrylic acid onto polypropylene fiber using simultaneous gamma ray irradiation technique, were evaluated. In general, an improvement in the mechanical behavior of the polypropylene fiber by grafting was observed. Denier and initial modulus of the fiber showed a linear increase with the percent graft, and elongation showed an opposite trend. The results have been explained in terms of reinforcing effect of poly(methacrylic acid) grafts and reduction in the segmental mobility of the polymeric chains. Tenacity also increases up to certain graft level, beyond which a sharp decrease occurs, probably due to the influence on the compactness of the macromolecular chains with the further grafting.
Morphological studies on the adhesion mechanism of pressure‐sensitive adhesives
Authors: Hino Kinnosuke , Hashimoto Hatsujiro 
Published: April 2003

AbstractThe breaking process of the thin film of pressure‐sensitive adhesives which are blends of natural rubber and the pentaerythritol ester of hydrogenated rosin and its surface structure after peeling off have been studied by electron microscopy. The dynamic observation of breaking process of the adhesives during the peeling has also been done by optical microscopy. The fibril structure with diameter of 50‐100 Å was observed under the breaking process of the thin film and on the surface after peeling off the adhesive tape consisting of 40‐60 wt % of resin. The previously proposed mechanism of adhesion which is based on the dynamic behaviors of fibrils and easy flow regions in the adhesives is confirmed by the electron microscopic observation.
Vinyl chloride–vinyl acetate kinetic modeling. I. Determination of radical efficiency factor
Authors: Heffelfinger Michael T. , Langsam Michael 
Published: April 2003

AbstractUsing dead end polymerization procedures, the copolymerization of vinylchloride–vinyl acetate was studied in laboratory scale reactors. Predictive kinetic models based on modified Hamielec equations were developed which were valid up to the limit of the experiments, 35% conversion. The efficiency factor (f) for the t‐butylperneodecanoate initiator was determined for a range of initiator concentrations in a comonomer mixture.
Removal of nonionic surfactant by systems based on chloromethylated polystyrene–poly(ethylene glycol)
Authors: Tashiro Tatsuo 
Published: April 2003

AbstractFor the purpose of obtaining compounds which can remove nonionic surfactants in water, chloromethylated polystyrene (CMPS) was allowed to react with triethylene glycol monomethyl ether (3EGMME), tetraethylene glycol (4EG), poly(ethylene glycol) (PEG) 200, 400, 600, 1000, and 1500. The amount of PEG groups combined with CMPS decreased with an increase in the molecular weight of PEG. The ability of the product to remove polyethylene glycol mono‐p‐nonyl phenyl ether (NP, n = 10), a nonionic surfactant, solutes in water was greater in the product with PEG of greater MW than that with PEG of smaller MW, and in the product with more PEG groups (mol/g prod.) than in that with less PEG groups. The removal behavior of the products conformed to Freundlich's adsorption formula. Constants of the formula, the effect of temperature on the constants, the effect of combined PEG groups on the removed amount, and the removal manner were studied.
Models of cellulose physical structure from the viewpoint of the cellulose I → II transition
Authors: Fink Hans‐Peter , Philipp Burkart 
Published: April 2003

AbstractSupermolecular structure of linters cellulose at the cellulose I–II phase transition is investigated by wide‐angle X‐ray scattering (quantitative phase analysis, degree of crystallinity by the method of Ruland and Vonk, and lateral crystallite sizes via peak separation by Pearson VII functions). A survey of models of cellulose structure recently discussed in literature is given. The compatibility of these models with the obtained WAXS results is checked. As a conclusion, some of the models especially the parallel–antiparallel transition of chain arrangement are outruled and a nonuniform fringed fibrillar model in connection with a conformation transition from bent to bent and twisted single chain conformation is preferred.
Studies of reactions with polymers. I. The reaction of maleic anhydride with PVA and the properties of the resultant
Authors: Chiang Wen‐Yen , Hu Chun‐Min 
Published: April 2003

AbstractGraft copolymerization of maleic anhydride (MA) onto PVA was carried out both in the presence and absence of the initiator. In the former case, the resultant was a copolymer containing a carboxylic acid and a keto‐olefinic side chain. Therefore, the reaction product, viscosity, gel content, and mechanical properties differed from the resultant of the latter, which was obtained by esterification of PVA by MA. Both resultants showed polyelectrolytes characteristics. The dependence of the grafting percentage on the concentration of the initiator, the concentration of the monomer, the reaction temperature, and the reaction medium was studied. Grafted copolymers after heat treatment showed remarkable mechanical strength in the wet state when compared with original PVA.
The curing behavior of resol. III. Effect of alkali metal hydroxides and alkaline earth metal hydroxides as catalyst for the cure of resol
Authors: Fukuda Akinori , Hasegawa Kiichi , Kawaguchi Yoshitaka , Horiuchi Hikaru 
Published: April 2003

AbstractThe effect of the addition of cure catalysts on the cure acceleration of ammonia free resol was investigated by means of Curelastometer. The resol which was prepared by the reaction between phenol and formaldehyde with molar ratio 1:1.2 in the presence of NaOH (0.02 mol to phenol) was neutralized with HCI. Catalyst selected from LiOH, NaOH, KOH, Mg(OH)2, Ca(OH)2, Sr(OH)2, and Ba(OH)2 was added to the resol, and curing behavior of the resol was examined. Both alkali metal hydroxides and alkaline earth metal hydroxides accelerate the curing of resol. The cure acceleration effect of barium hydroxide is the largest. In the relation between the kinds of catalysts and the cure acceleration effect, the larger the ion radius of catalyst the faster the cure of resol. Cure speed of the resol containing either sodium hydroxide or barium hydroxide as a curing catalyst increases with an increase in the amount of catalyst. Apparent activation energies of curing behavior of the resols containing the cure catalysts were in the range 17.0–21.3 kcal/mol.
Studies of reactions with polymers. II. The reaction of maleic anhydride with acrylonitrile onto PVA and the properties of the resultant
Authors: Chiang Wen‐Yen , Hu Chun‐Min 
Published: April 2003

AbstractGraft terpolymers were prepared by graft polymerization of a mixture of acrylonitrile (AN) and maleic anhydride (MA) onto PVA in DMSO solution using KPS as an initiator. Structure and solubility of graft terpolymers varied with the concentrations of KPS and MA. Both lower and upper critical values of KPS concentration varied with MA concentration, and the resulting reaction could be divided into three regions—crosslinked, hydrophobic, and hydrophilic regions. Structures of graft terpolymers were considered to be composed of homopolymer side chain grafted onto PVA while gelation occurred from the surplus radicals in PVA backbone to carry on the coupling reaction. The mechanical properties and viscosities increased with the increase of the wt % of AN in graft terpolymers; however, to increase AN content in PVA by increasing KPS concentration would bring about the oxidation scission and do damage to mechanical properties. Thus it becomes obvious that KPS can only be used at a suitable amount.
The physical basis of moisture transport in a cured epoxy resin system
Authors: Gupta V. B. , Drzal L. T. , Rich M. J. 
Published: April 2003

AbstractThe moisture transport characteristics of a difunctional epoxy resin cured with different amounts of metaphenylene diamine, using two cure cycles, are reported. Besides studying the kinetics of moisture sorption at 20, 50, 75, and 100°C, the investigations also included measurement of thermal expansion coefficients and dynamic mechanical transition of the dry and wet samples. The moisture sorption of the sample is shown to be related to its specific volume and hence to its fractional free volume. In the glassy state, the free volume is apparently in the form of frozen voids, and moisture sorption/desorption at this temperature is of the Langmuir type with little or no bond formation. At higher temperatures the free volume is generated predominantly through segmental motion of the α transition. The Henry's Law mode becomes operative, and the moisture can now form bonds. The possible effect of nonuniform crosslink density on moisture sorption is also considered.
Transport of penetrants in the macromolecular structure of coals III. Dynamic swelling of stiff polymer networks that simulate the coal structure
Authors: Barr‐Howell Barbara D. , Peppas Nikolaos A. , Squires Thomas G. 
Published: April 2003

AbstractThe structure of three cross‐linked polymers containing naphthalenic rings in their backbone structure was investigated by dynamic swelling and thermal analytic techniques. It was determined that the pyridine and n‐proplyamine transport in microparticles (40 μm) of these polymers was non‐Fickian, often approaching case II transport and sometimes even supercase II transport. The thermal analysis showed relatively stable structures up to about 350°C.
Investigations on methyl methacrylate polymerization course in the presence of petroleum asphalt group components
Authors: Bukowski A. , Liszyńska B. 
Published: April 2003

AbstractMethyl methacrylate photopolymerization was investigated in the presence of group components isolated from road asphalt D35. It was observed that all asphalt group components, particularly asphaltenes, had an inhibiting influence on the degree of MM conversion. Based on results of measurements of the viscosity‐average relative molecular mass of the fractions isolated from the reaction products, we can make a hypothesis that asphaltenes perform a role as polyfunctional chain conveyors.
Pyrolysis of model compounds of the flame retardant poly(N‐dimethylphosphonomethyl acrylamide)
Authors: Lawler Terry E. , Drews Michael J. , Barkerm Robert H. 
Published: April 2003

AbstractAn investigation of the thermal decomposition of N‐dimethylphosphonomethyl amides has shown that the major volatile products for decomposition above 300°C are methanol, the methyl ester of the carboxylic acid, the nitrile, the carboxylic acid, the N‐methyl amide, and the N,N‐dimethyl amide. Also, benzoic acid was the only volatile product detected in the decomposition of α‐benzamidomethylphosphonic acid. A mass balance for the decomposition of N‐dimethylphosphonomethyl benzamide at 420°C showed methanol and methyl benzoate to be the major volatile products. Methanol and benzonitrile formation increased with an increase in temperature at a faster rate than the other volatile products. The reaction of amides and phosphonates was further studied using sealed tubes in a furnace. Reaction of N‐methylbenzamide with dimethyl methylphosphonate at 307°C in a sealed tube produced methyl benzoate and N,N‐dimethylbenzamide. N,N‐dimethylbenzamide and dimethylmethylphosphonate were also shown to produce methyl benzoate at 310°C. After a 5‐min period more methyl benzoate was produced in the N,N‐dimethylbenzamide reaction than in the N‐methylbenzamide reaction. Also, addition of ethanol to the N,N‐dimethylbenzamide/dimethyl methylphosphonate reaction resulted in less ethyl benzoate methyl benzoate after heating at 310°C.
Flame‐retardant viscose–polyester fabrics
Authors: Nousianinen Pertti , Mattila‐Nurmi Marja‐Riitta 
Published: April 2003

AbstractFor many purposes the natural‐synthetic fiber‐blend fabrics are more suitable than pure natural or synthetic products. It is often possible to obtain a maximum in clothing and textile technical properties by compensating the defects of one fiber by using an other totally different fiber. Many problems, however, have arisen in the production of flame‐retardent fabrics because the use of synthetic fibers often makes the fire retardancy less effective. In our 2‐year research project different fire‐retardant (FR) viscose–polyesters fabrics were prapared at first in the laboratory scale. The natural type raw materials were Modal Prima viscose and normal FR–viscose cotton type staple fibers. The synthetic raw materials were FR–polyesters of the same type with two different flame retardants. Test fabrics were knitted in the laboratory by using seven blended yarns in the ratios 100/0, 80/20, 65/35, and 50/50 and vice versa. Cotton type PVC–fiber was also used in some experiments. All these test fabrics were also finished chemically by using normal crease‐resistant (DMU, DMEU, DMDHEU, and TMM) and flameretardant (N,‐methylolphosphonopropionamide and THPC) finishing chemicals. The textile and fire‐retardant properties of the original and finished fabrics were estimated by using addon, tensile strength, LOI‐value, and vertical flame test determinations. The mechanism of flame retardancy was also studied with DSC technique, P‐ and N‐analysis and char investigations. The test results of viscose/polyester studies were compared with the results of cotton/polyester studies. After laboratory studies the best methods for FR–viscose/polyester fabric production were chosen, and the fabrics were manufactured. The fabrics were home‐washed 20–50 times, and the textile and FR‐properties were determined after each 10 washings. These results were again compared with results of cotton/polyester fabrics.
New aspects in cationization of lignocellulose materials. IV. Modification of aspen wood meal with quarternary ammonium groups
Authors: Antal Miroslav , Šimkovic Ivan , Ebringerová Anna , Micko Michael M. 
Published: April 2003

AbstractTrimethylammonium‐2‐hydroxypropyl (TMAHP) derivatives of aspen wood were prepared by the reaction of wood meal with 3‐chloro‐2‐hydroxypropyltrimethylammoniumchloride (CHMAC) in alkaline medium. The TMAHP sample was fractionated and yields and exchange capacities (Q) of individual fractions were compared with beech sawdust fractions obtained under the same conditions. The most evident difference between the two studied wood types was the higher yield (14.5% of starting material) of water‐soluble TMAHP–hemicelluloses obtained from aspen wood.
Studies on thermal degradation of cellulose and cellulose phosphoramides
Authors: Kaur Baljinder , Gur I. S. , Bhatnagar Hari L. 
Published: April 2003

AbstractReaction of cellulose with hexamethylphosphoric acid triamide has been investigated under various physical conditions. Dimethylamine hydrochloride was found to be an efficient catalyst for the system. The thermal degradation of cellulose and its phosphoramide products in air was studied by DTA, TG, and DTG techniques from ambient temperature to 500°C. The data were processed for the various thermodynamic parameters following the methods of Freeman and Carroll, of Broido, and of Dave and Chopra. The energies of activation, Ea, for the degradation for various cellulose phosphoramide samples were found to be in the range of 92–136 kJ mol−1. These values were found to decrease with increase in the degree of substitution. A mechanism for the thermal degradation of cellulose phosphoramide has been proposed. The IR spectra of char residues of cellulose phosphoramide gave an indication of the formation of compounds containing CO and PO groups.