bluuebunny/crossref_metadata_2025 huggingface dataset:
Models of cellulose physical structure from the viewpoint of the cellulose I → II transition
Authors: Fink Hans‐Peter , Philipp Burkart
Published: April 2003

Supermolecular 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

Graft 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

The 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

Graft 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

The 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

The 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

Methyl 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

An 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

For 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

Trimethylammonium‐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

Reaction 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.
Mechanisms of antioxidant action: Time‐controlled photoantioxidants for polyethylene based on soluble iron compounds
Authors: Al‐Malaika S. , Marogi A. M. , Scott G.
Published: April 2003

The effects of two component combinations of soluble iron compounds on the rate of photooxidation and associated embrittlement times of low density polyethylene (LDPE) are examined. It is found that photoantioxidants retard the photo prooxidant effects of iron compounds giving controllable induction periods. In the case of the combination of a nickel dithiocarbamate (photoantioxidant) and an iron dithiocarbamate (photo prooxidant) a very wide range of embrittlement times can be obtained in which the induction period is controlled by the nickel complex and the post‐induction period rate by the iron complex.
Thermal degradation of stabilized rigid poly(vinyl chloride) monitored by microhardness measurements
Authors: Gonzalez Ana , Martin‐Gil Jesus , Saja Jose Antionio De , Rodriguez Ramiro
Published: April 2003

Microhardness testing is shown to be a simple and useful complementary technique in the study of thermal degradation of rigid PVC stabilized with different amounts of an organotin compound. An interpretation of the microhardness observation is made in terms of reactions between the polymer and the stabilizer.
Removal of polyethylene glycol mono‐p‐nonylphenyl ether and dodecylbenzenesulfonate by chloromethylated polystyrene–polyethylenepolyamines and –polyethyleneimines
Authors: Tashiro Tatsuo
Published: April 2003

The reactions of chloromethylated divinylbenzene crosslinked polystyrene (CMPS) with polyethylenepolyamines (PEPA), polyethyleneimines (PEI), 2‐methyl‐2‐oxazoline (MeOZO), and the hydrolysis of CMPS–MeOZO reaction products were carried out. The abilities of these products for removing a nonionic surfactant, polyethylene glycol mono‐p‐nonylphenyl ether (NP, n=10), solutes in water were investigated. Removal rates of NP by and the amounts of NP removed by CMPS–PEPA, –PEI, –MeOZO, and hydrolyzate of CMPS–MeOZO were compared. The adaptability of removal behavior of the products to the Freundlich's adsorption isotherm and the amounts of NP removed by unit masses of the products were investigated. The products also removed an anionic surfactant, sodium dodecylbenzene sulfonate (DBS), solutes in water. The mechanisms for removing NP and DBS were discussed.
On loci of acrylonitrile polymerization with bisulfite‐persulfate initiators under the conditions of low water/monomer ratio
Authors: Ito Seiichi , Plant Otake
Published: April 2003

In the preparation of acrylonitrile–vinylacetate copolymer (93:7 in weight) by continuous polymerization in aqueous medium using the complete mixing type reactor, the author and co‐workers studied the effects of the water/monomer ratio on polymer properties and polymerization. They reported that the structure of a polymer particle becomes more compact with decreasing water/monomer ratio. This was noted in studying the physical properties of the polymer and the formation of polymer particles in this system. 1,2 Here the author has performed kinetic studies based on the results of polymerization to determine the loci of the polymerization in the range of water/monomer ratio roughly from 1.75 to 4.0. Most of the primary radicals from the initiators attack the monomers in the aqueous phase to form monomer radicals attached to initiator fragments, and most of the monomer radicals grow to form polymer radicals until termination occurs in the aqueous phase. Hence, the loci of polymerization in this system are not the surfaces and inner parts of the polymer particles, the diameters of which are roughly from 20 to 60 μm observed by a microscope, but the aqueous phase excluding these particles.
Morphology of composite polymer emulsion particles consisting of two kinds of polymers between which ionic bonding intermolecular interaction operates
Authors: Okubo Masayoshi , Yamaguchi Seitaro , Matsumoto Tsunetaka
Published: April 2003

The morphology of particles (I) produced by seeded emulsion copolymerization of styrene (S) and sodium p‐styrene sulfonate (NaSS) with butyl acrylate (BA)‐methacryloyloxyethyl‐trimethylammonium chloride (QDM) copolymer particles as seed was examined in comparison with poly(butyl acrylate) (PBA)‐polystyrene (PS) composite polymer emulsion particles (II). In an electron microscopic observation, it was observed that II particles had an anomalous shape and the electron densities at different points in the particle were heterogeneous, whereas I particles had an almost spherical shape and the electron densities were homogeneous. The maximum tensile strength and toughnes were much larger in II than I. The dynamic mechanical studies indicate that II film had a macroheterogeneous structure consisting of PS‐rich and PBA‐rich phases, whereas I film had a microheterogeneous structure. These ressults suggest that there is an effect of intermolecular interaction between polymers of different kinds on the formation of heterogeneous structure in particles consisting of two kinds of polymers.
N‐phenyl piprazine‐polyester derivative as curing activator of unsaturated resins
Authors: Tanzi M. C. , Pornaro F. , Miuccio A. , Grassi L. , Danusso F.
Published: April 2003

An oligomeric compound (Pol‐2A) has been synthesized by a Michael‐type addition of N‐phenyl piperazine to double bonds of the maleic units of a polyester resin. This compound was used as activator (with benzoyl peroxide) in the curing of unsaturated polyester resins and compared in its efficiency with N,N‐dimethylaniline (DMA). Pol‐2A showed actiator characteristics comparable to those of DMA, with a wider range of gel times, and similar mechanical properties of the end products, with the advantage of a severe lowering of diffusibility and related environmental toxicity.
A dielectric study of the glass transition region in urethane elastomers modified by ionic bonds
Authors: Zieliński R. , Rutkowska M.
Published: April 2003

The uretane elastomers cross‐linked by the varying content of triethanolamine and 3‐bromine‐1,2‐propanediol have been investigated by means of dielectric spectroscopy. The complex character of the glass‐rubber transition has been determined. It results from different mechanisms of cross‐linking (urethane and ionic bonds). The influence of content of cross‐linking mixture on the microphase separation has been observed.
Cure kinetics of neat versus reinforced epoxies
Authors: Mijović Jovan
Published: April 2003

An investigation was carried out into the cure kinetics of neat vs reinforced epoxy systems. The formulations were composed of tetraglycidyl 4,4′‐diaminodiphenyl methane (TGDDM) epoxy resin and diaminodiphenyl sulfone (DDS). Glass was used as reinforcement. A series of isothermal differential scanning calorimetry (DSC) thermograms were run and analyzed by the proposed autocatalytic kinetic model. An increase in reaction rate was observed at higher temperature and higher DDS concentration in both neat and reinforced formulations. The presence of reinforcement had an effect on the cure kinetics. The observed effect, however, was not very pronounced. Slightly lower values of the reaction rate constant and longer times needed to reach the maximum reaction rate were recorded in reinforced systems. After reaching the peak value, the rate of reaction dropped off faster in reinforced formulations, resulting in lower average value of Hult, the ultimate heat of reaction. It was suggested that the reinforcement imposes restrictions on the molecular mobility of reactive species.
Time lag in diffusion
Authors: Ash Richard , Barrie James A.
Published: April 2003

Adsorption and desorption diffusion time lags are given for some homogeneous hollow cylinder and spherical shell membrane systems. The treatment relates to a constant diffusion coefficient with solution or sorption obeying Henry's law. Time lags for both “forward” and “reverse” flow have been determined and identities between them derived. For the hollow cylinder and spherical shell membrane systems considered here, there are only three distinguishable time lags.
Thermal cis‐trans isomerization and photofading of some azo dyes in poly(ethylene terephthalate) matrices: A kinetic study
Authors: Dubini‐Paglia Ernestina , Beltrame Pier Luigi , Marcandalli Bruno , Carniti Paolo , Seves Alberto , Vicini Loredana
Published: April 2003

The thermal cis‐trans isomerization of azo dyes XC6H4N=NC6H4N(C2H5)2 (where X is H, OCH3, CN, and NO2) in poly(ethylene terephthalate) matrices, below the glass transition temperature, and in dibutylphthalate solutions has been studied kinetically in the temperature range 20–60°C. Kinetic behavior in the polymer is characterized by two or three simultaneous first‐order processes with similar activation enthalpies. These processes reflect an unequal distribution of “tie‐molecules,” “folds,” and “cilia” in the amorphous region of the polymer. Lightfastness of the dyes in poly(ethylene terephthalate) films has been investigated. Polymer morphology strongly affected the photofading, but no significant influence was observed in the kinetic experiments.
Lignosulfonate polymerization: Effect of cross‐linking agents
Authors: Bialski A. M. , Bradford H. , Lewis N. G. , Luthe C. E.
Published: April 2003

Factors affecting the thermosetting properties of spray‐ or freeze‐dried, ammonium‐based spent sulfite liquor, a material rich in lignosulfonates, were investigated. It was found that purified lignosulfonates did not thermoset readily, unless either monomeric wood sugars or formaldehyde were present. Under the conditions employed, the monosaccharides were more effective than formaldehyde as thermoset accelerators. This may be due to the greater functionality of the intermediate decomposition products of the carbohydrates, which would create more reactive sites for intermolecular bonding with lignin. In contrast to previous findings, it was found that lignosulfonates (of mol wt ≥ 10,000) underwent polymerization, and subsequent thermosetting, more rapidly than their lower molecular weight counterparts. This was established by HPLC size exclusion elution chromatography of each sample following thermal treatment. It was also observed that wood did not affect the rate of thermosetting.
Effect of modified calcium phosphate surface on the aqueous polymerization of methyl methacrylate
Authors: Moustafa A. B. , Abd El‐Hakim A. A. , Badran A. S. , Abd El‐Ghaffar M. A. , Sakr M. A. I. E.
Published: April 2003

The aqueous polymerization of methyl methacrylate was carried out in the absence and in the presence of unmodified and modified calcium phosphate surface with adsorbed stearic acid from stearic acid benzene solution; this was found to accelerate the polymerization process. The acceleration was found to depend on the extent of modification. The apparent activation energy was also found to decrease with surface modification. It was also found that the calcium phosphate surface modified with stearic acid has an effect on the sedimentation rate and sediment volume in organic medium.
Copolymerization kinetics for 2‐isopropenyl‐2‐oxazoline (methods and results)
Authors: Dibona D. M. , Fibiger R. F. , Gurnee E. F. , Shuetz J. E.
Published: April 2003

The reactivity ratios for 2‐isopropenyl‐2‐oxazoline (IPO), a dual functional monomer, have been determined using a combination of gas chromatography, with an internal standard, and a new form of the integrated copolymerization equation. The results indicate a parallel trend with the reactivity ratios of styrene in spite of the large disparity in polarity between IPO and styrene.
Estimation of the inherent friction factor per main‐chain friction unit of liquid low‐molecular‐weight unsaturated polyesters
Authors: Kaštánek Alois , Balcr Miroslav , Bohdanecký Miloslav , Lešek František , Kitzler Jaroslav
Published: April 2003

The temperature dependence (at 323–443 K) of the zero‐shear viscosity η of about 30 nonfractionated samples of an unsaturated polyester (300 < Mn < 1500) was analyzed and the parameters of the Vogel equation describing the η(T) dependence were estimated. Their dependence on the molecular weight is discussed. The inherent friction factor per main‐chain friction unit, ξo, has been evaluated for 15 < Zn < 70 (where Zn is the number‐average number of main‐chain friction units) and compared with the values available for other polymers.
Thermal degradation of butadiene–styrene‐based rubber
Authors: Abu‐Zeid M. E. , Youssef Y. A. , Abdul‐Rasoul F. A.
Published: April 2003

Thermal degradation of some commerically available rubber based on butadiene–styrene copolymers are studies as a function of composition, temperature, and heating periods using photoacoustic spectroscopy (PAS) technique. It was found that random copolymers are more degradable than block copolymers and that the latter is more degradable than alternate copolymers. Mechanistic schemes leading to the thermal degradation of these synthetic rubbers are given together with a qualitative explanation of the relation between their composition and their thermal stabilites.
Molecular weight distribution of the graft copolymer comprising mixtures of styrene and acrylamiae on cellulose acetate film by means of gel permeation chromatography
Authors: Bhattacharyya S. N. , Maldas D.
Published: April 2003

Styrene portion of the radiation‐induced graft copolymer comprising styrene and acrylamide was separated by acid hydrolysis and the effects of various grafting parameters (e.g., reaction time, reaction temperature, solvents, monomer composition, etc.) on molecular weight distribution were evaluated by means of gel permeation chromatography. When a single monomer or mixture of two monomers are grafted, the molecular weights is found to increase, but polymer dispersity decreases with the increase of reaction time or reaction temperature except at a higher reaction time due to the continuous enlargment of the growing chain through increased swelling and molecular motion of the trapped radicals. At higher reaction time the degradation of the graft chains lead to lower molecular weight and higher polymer dispersity. Effects of solvents (e.g., methanol, ethanol, and t‐butanol) on the molecular weight and molecular weight distribution were discussed on the basis of swelling property and chain transfer constants of the solvents. Styrene‐type graft radical being long lived compared to acrylamide type, gave long‐chain styrene graft with the increase of styrene content in the reaction mixture. A comparison of the effect of one‐and two‐component systems on a molecular weight distribution is also discussed.
Polymers from renewable sources. III. Hydroxy‐terminated myrcene polymers
Authors: Cawse J. L. , Stanford J. L. , Still R. H.
Published: April 2003

A range of hydroxy‐terminated polymyrcenes has been prepared using hydrogen peroxide initiated polymerization of pyroysate grade, β‐myrcene in n‐butanol solution at 100°C. An oligomeric fraction, containing a large proportion of dimeric material formed via the Diels–Alder reaction, always accompanies the major polymeric fraction. Procedures are described for the removal of this oligomeric material. Polyols so prepared and purified had number average molecular weights (Mn) between 4000 and 2000 g mol−1 at low and high initiator concentrations, respectively, with corresponding number average functionalities (fn) between 1.3 and 2.3 and polydispersities (Mw/Mn) of ∼1.3. The microstructure of the polyols was investigated using NMR spectroscopy from which the main mode of propagation during polymerization of myrcene was deduced to be 1,4 addition across the conjugated double bonds. Glass transition temperatures of the polymyrcenes measured by differential scanning calorimetry were in the range −50–60°C.
Grafting of 2‐hydroxyethyl methacrylate and methyl methacrylate onto chrome tanned collagen fibers
Authors: Klásek A. , Kaszonyiová A. , Pavelka F.
Published: April 2003

Grafting of 2‐hydroxyethyl methacrylate and methyl methacrylate onto chrome tanned collagen fibers, initiated by the bisulfite/pesulfate redox system, has been investigated. Using the method of statistical planning of experiments, regression equations have been obtained describing the effects of the monomers concentration and the composition of the initiating system on the monomers conversion, degree of grafting and on physical properties of grafted collagen. The relationship between the polyacrylate content in the composites prepared and their swelling ability, water absorption capacity, and the tensile strength is discussed.
Miscible blends of poly(styrene‐co‐acrylonitrile) and poly(α‐methyl styrene‐co‐acrylonitrile) with poly(methyl methacrylate) containing sterically hindered amine group
Authors: Goh S. H. , Lee S. Y. , Siow K. S.
Published: April 2003

Poly(methyl methacrylate) containing a small amount of pendant 2,2,6,6‐tetramethylpiperidinyl group was found to be miscible with poly(styrene‐co‐acrylonitrile) and with poly(α‐methyl styrene‐co‐acrylonitrile). The poly(α‐methyl styrene‐co‐acrylonitrile) blends exhibited lower critical solution temperatures. Phase separation of the poly(styrene‐co‐acrylonitrile) blends could not be induced by heating up to 270°C.
Morphological, structural, and interfacial changes produced in composites on the basis of polypropylene and surface‐treated sepiolite with organic acids I. Surface treatment and characterization of the sepiolites
Authors: Acosta J. L. , Ojeda M. C. , Morales E. , Linares A.
Published: April 2003

This research was conducted in order to gain a better knowledge of the possibilities deriving from sepiolite as a polypropylene filler. Special stress has been laid on the study of morphological, structural, and interfacial changes produced by the simple incorporation of sepiolite in the polymeric matrix, as well as on the effects of these changes on all the properties of the resulting composites. In the light of the relevance of filler surface activity with regard to the physical behavior of these materials, we modified this activity through chemical reaction of the superfacial silanol groups in the sepiolite with different aliphatic organic acids. This paper includes a description of the esterfication procedures and a characterization of the different sepiolites obtained.
Structure and properties of talc‐filled polyethylene and nylon 6 films
Authors: Murthy N. S. , Kotliar A. M. , Sibilia J. P. , Sacks W.
Published: April 2003

Water vapor transmission rates can be reduced by as much as 50% in polyethylene by using talc as a filler. The oxygen permeability as well as water vapor transmission rates are similarly reduced by talc in nylon 6 films. The films show low elongation at break and reduced breaking strenth in the presence of talc. The yield strength and the modulus increase with the amount of talc, whereas the elongation at yield decreases. The mechanical and the barrier properties change with the size of the filler, the smaller size being more favorable. Talc probably acts as a nucleating agent and increases the crystallinity in polyethylene and nylon. Polyethylene unit cells in talc‐filled films are oriented with the (110) planes parallel to the (001) planes of talc. Nylon 6 crystals, which are in the α form in the presence of talc, are oriented with the hydrogen bonded sheets, the (002) planes, parallel to the (001) planes of talc. In both polyethylene and nylon 6, talc is oriented with the c‐axis normal to the plane of the film, i.e., with the broad faces of talc flakes in the plane of the film. Lattice matching between the polymer and talc suggests epitaxy to be a contributing factor for the observed orientation of polyethylene and nylon 6 crystals.
Orientation suppression in fibers spun from polymer melt blends
Authors: Brody H.
Published: April 2003

The addition of very small amounts of carefully selected polymers by melt blending has been found to radically change the flow properties at spinning of conventional polymers such as polyethylene terephthalate, nylon 66, and polypropylene. This has a large effect on spun properties, especially at high wind‐up speeds. The additive polymers used have included liquid crystal polymers, polyethlene, polyethylene glycol, and nylon 66. A major phenomen is a considerable lowering of spun orientation, or wind‐up speed suppression. In order to activate the non‐liquid crystal polymers to achieve this effect special spinning conditions are necessary. The mechanism is viewed as being nonuniform extensional flow in a two‐phase system and not molecular interaction.
Effect of mode of agent removal on pore structure of liquid ammonia treated cotton cellulose
Authors: Bertoniere N. R. , King Walter D. , Rowland Stanley P.
Published: April 2003

The pore structures of three liquid‐ammonia‐treated cottons were compared via a reverse gel permeation chromatographic technique. Cotton battings were treated with liquid ammonia which was removed by volatilization at ambient temperature or at elevated temperature and by water exchange. Three series of water‐soluble solutes were used to study the elution characteristics of whole fiber columns prepared from these battings. The solutes were oligomeric sugars, ethylene glycols, and glymes (ethylene glycol dimethyl ethers) having molecular dimensions in the range of conventional finishing agents for cotton. All three liquid ammonia treatments increased the internal pore volumes accessible to small molecules. The greatest increase was noted when the ammonia was removed by water exchange and the least when volatilization at elevated temperature was employed. Ambient temperature volatilization had an intermediate effect. Decreases in the volumes of large pores were effected by ammonia treatments followed by volatilization at ambient or elevated temperature. Water exchange of the ammonia resulted in an increase in the volume of large pores as well as of the small pores.
Wood processing variables and adhesive joint performance
Authors: Ebewele Robert O. , River Bryan H. , Koutsky James A.
Published: April 2003

In order to obtain a bonded wood product from the tree, wood must be subjected to a series of processes. These include, among others, vital processes like drying of the green wood and machining of the surfaces of the dried wood in preparation for bonding. However, when wood is machined with dull blades, thermal degradation of the wood frequently occurs. The effects of kiln drying and thermal degradation of wood on the performance of the adhesive joints subsequently formed from such wood were investigated. Tapered double cantilever beam (TDCB) test specimens obtained from hard maple and phenol–resorcinol–formaldehyde (PRF) adhesives were used in the investigations. The enhancement of fracture energy due to the reduction in the moisture content of wood, the improved performance of adhesive joints due to rejointing of wood surfaces before bonding, and the reduction of adhesive joint strength resulting from thermal degradation of wood are presented and discussed.
Wood–phenol adhesives prepared from carboxymethylated wood. I
Authors: Shiraishi Nobuo , Kishi Hajime
Published: April 2003

Preparation of carboxymethylated wood (CM wood)–phenol resin adhesives has been attempted by two methods, “kneading method” and “solvolysis method,” and their adhesion strength has been studied. The two preparation methods differ in the dissolution step. In the case of the kneading method, CM wood was dissolved in aqueous phenol by kneading at 100–120°C under shear, whereas, in the case of the solvolysis method, the dissolution was facilitated by phenolysis at 80°C in the presence of appropriate amounts of hydrochloric acid. The wood‐based adhesive prepared by the solvolysis method revealed excellent and enhanced applicability compared with that of the adhesive prepared by the kneading method, although the latter can be used as an adhesive for wood. Adhesion strength of these adhesives was enhanced when poorly substituted CM wood and appropriate amounts of formaldehyde were used in the resin preparation. A crosslinking agent for carboxymethyl cellulose, that is, polymeric MDI, was also added just before application. The water‐proof adhesion strength was higher than the JIS specification for phenol resin adhesives for this modification.
In vivo and in vitro blood compatibility of polyelectrolyte complexes formed between cellulose derivatives
Authors: Ito Hiraku , Miyamoto Takeaki , Inagaki Hiroshi , Noishiki Yasuharu , Iwata Hiroo , Matsuda Takehisa
Published: April 2003

The blood compatibility of cellulosic polyelectrolyte complexes (PECs) and the effect of excess charge in PEC on the blood compatibility were examined in detail by both in vivo and in vitro blood tests. For this purpose, two types of quaternary ammonium cellulose derivatives were prepared by treating cellulose or hydroxyethyl cellulose with glycidyl trimethylammonium chloride. In vivo blood tests were made by implanting the polymer‐coated suture into a jugular and femoral vein of a dog. In vitro blood tests include the measurement of whole blood coagulation time on polymer‐coated glass tubes, platelet adhesion measurements using a column packed with polymer‐coated glass beads, and a measurement of activation of the intrinsic coagulation system. It was found that among the PECs examined, the PECs containing quaternary ammonium derivatives as polycation components have an excellent blood compatibility. The experiments on the effect of excess charge in PEC revealed that (i) the relative coagulation time of whole blood is almost independent of the mole ratio of polycation to polyanion component within the mole ratios examined, being in good agreement with those by in vivo blood tests, but (ii) platelet adhesion increases with increasing the mole ratio of polycation/polyanion in the PEC, and (iii) the activation of the intrinsic coagulation system increases with decreasing the mole ratio.
Rheological properties of coatings during drying processes
Authors: Watanabe Koichiro , Amari Takeshi
Published: April 2003

Coatings such as paints and printing inks transferred on substrates change from viscous liquids to viscoelastic solids during drying processes and finally become a hardened film. In order to investigate more precisely the viscoelastic properties of coatings during liquid‐to‐solid conversion, we developed the same type of ultrasonic rheometer as employed by Mason et al., in which the reflection coefficient technique is utilized. The complex modulus can be determined by the reflection coefficient and the phase shift. Using this rheometer, we can obtain the viscoelastic properties of coatings at various stages of drying at infinitesimal shear strain at the frequency of 3 MHz.

The viscoelastic properties of a commercial offset litho ink which was dried by oxidative polymerization were measured at various temperatures. From the results of viscoelastic measurements, the drying of ink seems to be accelerated remarkably with increasing temperature. As the drying processes progress, a three‐dimensional network structure may be formed in the ink film with the aid of oxidative polymerization. The drying‐time dependence of G′ is different from that of G″. From the drying‐time dependences of G′ and G″, we can quantitatively deduce the internal structure of printing ink films during drying processes and provide a physical explanation for various drying stages. The dispersed pigments in a coating seem to play an important role in film formation and affect the mechanical properties of the drying film.
Effect of cryoground rubber on properties of NR
Authors: Phadke A. A. , Bhowmick A. K. , De S. K.
Published: April 2003

The influence of cryoground rubber (CGR) on the curing characteristics, physical properties, network structure, and failure behavior of natural rubber (NR) has been investigated. CGR was added at two different levels of curatives and in two different ways (i) in powder form and (ii) in mill‐sheeted form (obtained by mechanical treatment of CGR in a two‐roll mill). The form of CGR and level of curatives affect the processing characteristics and technical properties of CGR–NR blends. The acetone extractables in the CGR were found to affect the curing characteristics, but no significant effect on the physical properties was observed. Model mixes were prepared by adding partially vulcanized NR compound in the matrix of the same compound. A three‐layer model was set up to study the diffusion of sulfur from the NR matrix phase to the CGR phase. Scanning electron microscope studies of the fractured surface revealed that the mechanical treatment of CGR effects improved adhesion of CGR to NR matrix and the compatibility between the two phases. CGR acts as an inert filler in NR.
Novel anion exchange membranes having fluorocarbon backbone: Preparation and stability
Authors: Matsui Kiyohide , Tobita Etsuko , Sugimoto Kikuo , Kondo Kiyosi , Seita Toru , Akimoto Akira
Published: April 2003

Anion exchange membranes with excellent durability were prepared by chemical modification of Nafion. The modification was achieved by transformation of the sulfonic acid group into quaternary ammonium group. Namely, Nafion membrane was first converted into an amide‐type membrane. Reduction of the carbonxyl group to methylene followed by quaternarization with alkyl iodide resulted in the formation of an anion exchange membrane. The electric resistance of the resulting membranes depends on the equivalent weight of the starting membranes (4.4–6.0 Ω cm2 in 0.5N NaCl). The characteristics of the membranes are the excellent stability toward chemical substances such as organic solvents, oxidizing agents, acids, etc. For example, the membranes are stable in aqueous saturated chlorine solution at 60°C for 1000 hr.
Long‐time sulfenamide‐accelerated sulfur vulcanization of natural rubber/chlorobutyl rubber compounds
Authors: Ducháček Vratislav , Kuta Antonín
Published: April 2003

Sulfenamide‐accelerated sulfur vulcanization of natural rubber/chlorobutyl rubber compounds has been investigated at temperatures from 155 to 175°C over 0.1 to 400 min. Continuous measurements in a Cone Rheometer were used to estimate the extent of crosslinking, which was plotted against cure time. On the basis of a kinetic analysis, two first‐order vulcanization reactions, crosslinking and degradation, have been evaluated. Over the temperature range studied, there is no significant difference between the values of activation energy for these reactions. The rate of the degradation is slower by a factor of 20 than the rate of crosslinking. The degradation reaction can be limited by increasing the “efficiency” of the vulcanizing system.
Effect of diisocyanate structure on viscoelastic, thermal, mechanical and electrical properties of cast polyurethanes
Authors: Pandya M. V. , Deshpande D. D. , Hundiwale D. G.
Published: April 2003

Structure property relationship of four different diisocyanates is studied in detail. The isocyanates selected are TDI, MDI Crude, HDI, and IPDI. Physical properties such as mechanical, dynamic mechanical, electrical, and thermal are studied. Dynamic mechanical analyses are based on the compound resonance principle. Among all, IPDI‐based polymer showed mediocre trend and TDI‐based polymer showed best properties.
Effect of fillers on the compatibility of polymer blends
Authors: Kalfoglou Nikos K.
Published: April 2003

The effects of carbon black, talc, and ultrafine silica filler, at different filler, loading, on the compatibility of two binary blends was examined. These were, the mechanically compatible polyurethane (PU)/poly(vinyl chloride) (PVC) at 25/75 weight ratio, and the poly(ε‐caprolactone) (PCL)/styrene–acylonitrile (SAN) copolymer (with 30% AN content), at the 50/50 blend composition. For the former system, both dynamic mechanical analysis (DMA) and DSC measurements indicated that, depending on the filler surface, boundary layers are formed at the filler–matrix interface shifting the PU relaxation to higher temperatures. No significant effect was observed for the PVC component. Though the mechanical spectra are also affected, essentially no Tg shifts were observed for the PCL–SAN system. A qualitative explanation of selective filler activity towards the blend components was given by invoking the matrix–filler basic–acidic nature. Overall, the fillers had no compatibilizing effect on the blend. Using available theory both DSC and the DMA techniques agree in their estimate of the boundary layer thickness. Moduli data were also analyzed using mechanics models proposed for composite systems.
Determination of residual unsaturation in highly crosslinked, dough‐moulded poly(methyl methacrylate) dental polymers by solid‐state 13C NMR
Authors: Earnshaw Richard G. , Price Carole A. , O'Donnell James H. , Whittaker Andrew K.
Published: April 2003

Methyl methacrylate has been copolymerized with eight multifunctional, cross‐linking comonomers in mixtures containing poly(methyl methacrylate) to give highly crosslinked polymers for trial as dental resins. These insoluble, optically opaque polymers have been characterized by solid‐state 13C Nuclear Magnetic Resonance spectroscopy. The crosslinking comonomer could be identified from the appropriate resonances in the solid‐state spectra. Unreacted methacrylate groups could be determined quantitatively from the resonance at 167 ppm due to CO adjacent to CC at concentrations down to at least 0.5% of the total CO. The final conversion of CC double bonds in the comonomer depended on the nature and length of the spacer segment between the reactive methacrylate groups.
Diffusion of an acid dye in nylon—in relation to sorption and diffusion of a gas in glassy polymers
Authors: Sada Eizo , Kumazawa Hidehiro
Published: April 2003

The steady‐state permeation rate data of an acid dye in a nylon film were analyzed via dual‐mode sorption and mobility model based on gradients of concentration. The model used incorporates diffusion in a porelike region, unlike diffusion of a gas in a glassy polymer. There was some possibilities of the Nernst to the Langmuir mode diffusion jump, and the diffusivity was estimated.
Studies on the radiation stability of ion exchange membranes
Authors: Ramachandhran V. , Misra B. M.
Published: April 2003

This article deals with some aspects of γ‐radiation stability of (phenolsulfonic acid, PSA) cation exchange membranes synthesized in the laboratory. The changes in cation exchange capacity, moisture content, coion sorption, concentration potential, area resistance, counterion transference number, and solute flux of the membranes were evaluated before and after irradiation. The membrane samples were irradiated under wet conditions using a 60Co source up to a total dose of 18.65 Mrads. The experimental data point out the possibility of degradation of PSA membranes beyond a dose of 9.78 Mrads, resulting in the loss of functional groups from membrane matrix.
The preparation and properties of acrylic and methacrylic acid grafted cellulose prepared by ceric ion initiation. II. Water retention properties
Authors: Vitta S. B. , Stahel E. P. , Stannett V. T.
Published: April 2003

Bleached sulfite softwood pulp and the corresponding paper have been grafted with acrylic and methacrylic acids and a number of other monomers. A practical, all aqueous, ceric ion method was used as described in Part I of this series. The water and saline retention values of the grafted pulps were determined. Super water sorbency, up to 48 g/g, were obtained after suitable post treatments. A number of variables were studied including the effects of pH, counterion, crosslinking, drying, and beating. It was gratifying that drying did not affect the effeciency of water or saline water retention. Useful linear functional relationships were found between the saline water retention values and the logarithm of the percent sodium chloride in the water. The two “model” parameters of the plots also correlated well with the water retention values and with the degree of grafting expressed as the ion exchange equivalents of the pulps. The osmotic pressure approach to the water sorption as developed by Grignon and Scallan5 coupled with the restraining forces of the grafted polymer itself is used to interpret the process.