bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrokinetic properties of polyformaldehyde fibers
Authors: Lokhande H. T. , Salvi A. S. 
Published: April 2003

AbstractElectrokinetic properties, namely, zeta potential (ζ), surface charge density (σ), and surface conductivity (Ks) of polyformaldehyde fibers [poly(oxymethylene) fibers] have been studied in the presence of direct dyes, with or without surfactants and an electrolyte. The anionic dyes increased the negative zeta potential of fibers. The increase in ζ was found to be a function of concentration and basicity of the dye in the streaming solution. Thus, the tetrabasic dye gave higher value of negative ζ than the equivalent concentration of the dibasic dye. The cationic surfactant brought about a decrease in negative ζ, giving a point of inflection, while the anionic surfactant increased it. The nonionic surfactant brought about a certain reduction in negative ζ, but failed to give a point of inflection. In the presence of a direct dye, the cationic surfactant brought about considerable reduction in negative ζ, to give a point of inflection. The presence of an electrolyte in the streaming dye solution progressively lowered the negative ζ. In general, σ increased with the increase in the concentration of either a dye or an electrolyte in the presence of a given concentration of the dye in the streaming solution. Results on Ks indicated that the surface conductivity of the fibers is a function of concentration of dye, surfactant, and electrolyte. It was, however, observed to be independent of the nature of the surfactant. Although both the dibasic and tetrabasic direct dyes brought about an increase in Ks, the extent of increase was dependent upon the basicity of the molecules.
Morphology and mechanical properties of injection‐molded specimens of two‐phase polymer blends
Authors: Han C. D. , Villamizar C. A. , Kim Y. W. , Chen S. J. 
Published: April 2003

AbstractAn experimental study was carried out to investigate the moldability of polymer blends which form two phases in the molten state and the effect of mixing on the morphology and mechanical porperties of molded specimens. Blends of polystyrene with polypropylene and blends of polystyrene with high‐density polyethylene were used for this study. A plunger‐type injection molding machine (Van Dorn) was employed for molding specimens. To improve the mixing performance of the plunger machine, a Static Mixer (Kenics Corp., Super Nozzle) was installed between the heating cylinder and the sprue. A number of different molding conditions (injection pressure, temperature, injection time, cooling time) were varied, and molded specimens were collected under each molding condition. The specimens were used for studying the degree of dispersion in the blends and for determining the mechanical properties. A differential thermal analysis (DTA) experiment was also carried out to determine the degree of dispersion of the blends in molded specimens. It was found that a linear correlation exists between the blend composition and thermal spectra area of the blends tested.
Pyrolysis–molecular weight chromatography–vapor‐phase infrared spectrophotometry: An on‐line system for analysis of polymers. III. Thermal decomposition of polysulfones and polystyrene
Authors: Kiran Erdoǧan , Gillham John K. , Gipstein Edward 
Published: April 2003

AbstractThe thermal decomposition of poly(butene‐1 sulfone), poly(pentene‐1 sulfone), poly(hexene‐1 sulfone), poly(styrene sulfone), and polystyrene was investigated in helium at a heating rate of 20°C/min using an experimental system which consists of a programmable pyrolyzer, a thermal conductivity detector, a mass chromatograph, and a vapor‐phase infrared spectrophotometer. Poly(butene‐1 sulfone), poly(penetene‐1 sulfone), and poly(hexene‐1 sulfone) displayed two‐step decomposition; the primary products of decomposition at both steps were the comonomers (olefin and SO2). For poly(styrene sulfone), in addition to styrene and SO2, products with molecular weights corresponding to dimers of styrene were observed. Decomposition of this polymer was compared with that of polystyrene, which formed mostly monomer.
A comparison of melt fracture initiation conditions in capillaries and slits
Authors: Vlachopoulos J. , Chan T. W. 
Published: April 2003

AbstractAn experimental study was carried out with the objective of comparing the critical conditions for the onset of gross extrudate distortion, usually called melt fracture, in capillaries and slits. Narrow and broad molecular weight distribution polystyrenes as well as low‐ and high‐density polyethylenes were used. The onset of melt fracture was observed to take place at higher shear stresses in slits than in capillaries. It is argued that the flow‐average value of the recoverable shear strain should be used as the criterion for the initiation of melt fracture.
Thermal degradation of polymers. XV. Vacuum pyrolysis studies on poly(p‐methoxystyrene) and poly(p‐hydroxystyrene)
Authors: Still R. H. , Whitehead A. 
Published: April 2003

AbstractThe monomers p‐hydroxystyrene (p‐HS) and p‐methoxystyrene (p‐MS) have been synthesized and polymerized using azobisisobutyronitrile as free‐radical initiator. The polymerization behavior of p‐HS is anomalous, and a mechanism is suggested to account for this phenomenon. Poly(p‐hydroxystyrene) (PHS) and poly(p‐methoxystyrene) (PMS) homopolymers have been subjected to vacuum pyrolysis at temperatures in the range of 300–500°C. The products of degradation have been identified and qualitatively and quantitatively analyzed and the degradation behavior of the two systems compared with polystyrene. PHS shows anomalous behavior resulting from the high reactivity of the p‐HS monomer and the facility for transfer afforded by the proton of the hydroxyl substituent. Mechanisms to account for the degradation behavior of each system are discussed.
Thermal degradation of polymers. XVI. Thermal analysis studies on poly(p‐methoxystyrene) and poly(p‐hydroxystyrene) in air and nitrogen
Authors: Still R. H. , Whitehead A. 
Published: April 2003

AbstractComparative thermal degradation studies have been made in air and nitrogen on polystyrene (PS), poly(p‐methoxystyrene) (PMS), poly(p‐hydroxystyrene) (PHS) and p‐hydroxystyrene/styrene copolymers (p‐HS/S) by thermal analytical methods (TG and DSC). The degradation behavior shown by these polymers in an oxidizing or inert atmosphere is different. PMS and PS, however, degrade in a similar manner in the same test atmosphere, suggesting that similar degradation mechanisms are operative for these systems. Polymers containing p‐HS behave differently to PMS and PS in both atmospheres. Their behavior in air is discussed it terms of the antioxidant effect of the phenolic hydroxyl grouping and the related crosslinking reactions. In nitrogen, the anomalous behavior is discussed in terms of the observed carbonization reaction.
Postdecrystallization rates of grafted fibers and their effect on fiber elasticity. I. Effect of zinc chloride concentration
Authors: Williams J. L. , Piatrik Milan , Choi Sam‐Kwon , Stannett V. 
Published: April 2003

AbstractRayon yarns grafted with poly(ethyl acrylate) become highly elastic following decrystallization in aqueous zinc chloride solutions. An increase in temperature speeds up the decrystallization rate but does not have a substantial effect on the ultimate elongation properties of the grafted fiber. Increasing the concentration of zinc chloride does not have a marked change in the extension properties of the grafted fiber until 70% zinc chloride. At this saturated concentration, there is a sudden and dramatic change in the elastic properties of the grafted fiber. In fact, the grafted fibers after decrystallization in 70% zinc chloride have elongations in excess of 800%.
Graft copolymerization of vinyl monomers onto modified cottons. VIII. Dimethylaniline–benzyl chloride‐induced grafting of methyl methacrylate onto partially carboxymethylated cotton
Authors: Hebeish A. , El‐Rafie M. H. , Khalil M. I. , Bendak A. 
Published: April 2003

AbstractThe feasibility of dimethylaniline (DMA)–benzyl chloride (BC) mixture to initiate graft polymerization of methyl methacrylate (MMA) onto partially carboxymethylated cotton was examined. The graft yield depends on the nature of the solvent used along with water; ethanol proved to be the best at a water;ethanol ratio of 90:10. Considerable grafting occurred in the presence of acetic acid at a concentration of 200 mmol/l. Higher concentrations of this acid decrease grafting significantly. The graft yield obtained in the presence of formic acid was much lower than that obtained in the presence of acetic acid. Inclusion of hydrochloric or sulfuric acid in the graft polymerization system prevent grafting. A DMA–BC mixture at a concentration of 0.08:0.087 mole/l. constitutes the optimal concentration for grafting. This contrasts with 0.32:0.35 mole/l. for total conversion. The rate of grafting increases by raising the polymerization temperature; it follows the order 50°>60°>65°>70°>75°C. Furthermore, increasing the monomer concentration caused a significant enhancement in the graft yield and total conversion.
Multiple steady‐state solutions in an isothermal perfectly mixed flow reactor
Authors: Ahmad Abu , Treybig Mike N. , Anthony Rayford G. 
Published: April 2003

AbstractThe effect of multiple steady solutions in isothermal perfectly mixed flow reactors is illustrated for polymerizations which have autocatalytic rates of initiation and no termination reactions. For feed conditions where more than one steady condition can exist, longer holding times may not necessarily yield higher molecular weight polymer or higher monomer conversions.
Graft copolymers of starch–polyacrylonitrile prepared by ferrous ion–hydrogen peroxide initiation
Authors: Stout Edward I. , Trimnell Donald , Doane William M. , Russell Charles R. 
Published: April 2003

AbstractThe effect of concentration, reactant ratios, temperature, and starch pretreatment on grafting of acrylonitrile onto starch were studied. Grafting was efficient at high concentrations (8–12% starch) when granular starch was used. The molecular weights for grafted polyacrylonitrile (PAN) were higher when gelatinized starch was used, but grafting efficiencies (grafted PAN/total PAN) were much lower. The molecular weight of the grafted side chain increased with increased concentration of reactants. The grafting frequency was highest when the reaction mixture was kept at 5°C and decreased with increased swelling of the starch. The starch–polyacrylonitrile graft copolymers were saponified and dried to give products which absorbed 75–440 ml H2O per gram and 20–70 ml synthetic urine per gram.
Poly(aryloxyphosphazenes) and a flame retardant foam
Authors: Thompson James E. , Reynard Kennard A. 
Published: April 2003

AbstractPlastics and elastomers were prepared, physical state determined by the side chains attached to the phosphorus–nitrogen backbone. The poly(aryloxyphosphazenes) displayed a high degree of flame retardancy in the uncured, unfilled state. Limiting oxygen index (LOI) values varied from 27 to 33 for nonhalogenated materials and from 38 to 65 for halogenated materials. These values qualify all poly(aryloxyphosphazenes) studied as flame retardants according to the generally accepted definition (LOI ≥ 27). Materials subjected to the National Bureau of Standards Smoke Test gave encouraging results. The [(C6H5O)2PN‐(4‐C2H5C6H4O)2PN]n elastomer was investigated for application as a fire retardant insulating foam. Closed‐cell foams produced from this copolymer showed much improved fire retardancy and smoke generation compared to commercially available fire retardant foam insulations.
Changes in NMR characteristics of cotton and wool during water adsorption
Authors: Svanson S. E. 
Published: April 2003

AbstractNMR signals have been followed for cotton and wool materials during humidification of the fibers. It is shown that the adsorbed water is present in two main states of different mobilities and that the relative velocities for the penetration of the water to these different states can easily be followed. It has been observed that the amount of adsorbed water with low mobility, in the primary sites, grows more rapidly in cotton than in wool during the sorption. Overlap between the signal contributions from water with reduced mobility and from the polymer chains makes observations of the segmental mobility of the polymer chains difficult.
Viscosity index. II. Correlation with rheological theories of data for blends containing n‐octadecyl acrylate
Authors: Jordan Edmund F. , Smith Stephen , Zabarsky Ruth D. , Austin Robert , Wrigley A. N. 
Published: April 2003

AbstractThe viscosities obtained for the copolymer blends of the previous paper were correlated with several relations derived to describe more fundamental behavior of polymer–diluent mixtures at both infinite dilution and finite concentrations. Only the most efficient blends showed any appreciable expansion of hydrodynamic volume as temperature increased from 25° to 98.9°C. However, in spite of restricted coil expansion, all of the copolymers were effective viscosity index improvers. The mechanism of viscosity index improvement in multigrade oils was shown to be largely regulated by the translational friction generated by the polymer coils. This greatly increased the apparent negative entropy change of the blends; the enthalpy change characteristic of the base oil was retained. Efficiency resulted from coil contraction at low temperatures, but enthalpy decrease below that of the base oil was small. In contrast, viscosity index improvement using higher molecular weight solvents was accompanied by large enthalpy increases. Thus, undesirably high viscosities resulted at low temperatures. The structure of these blends was uncomplicated by polymer chain entanglements; unit values of the Fox‐Flory exponent were obtained for the relation between viscosity and weight‐average carbon backbone length. The lack of evidence for coil compression in the thermodynamically miscible blends above a critical reduced concentration was anomalous. Intermingling of side chains and their interaction may have overcome normal excluded volume effects.
The effect of carriers on drawn poly(ethylene terephthalate) filaments
Authors: Ingamells W. , Yabani A. M. 
Published: April 2003

AbstractThe effect of various organic compounds on the birefringence equilibrium shrinkage and swelling of poly(ethylene terephthalate) filaments was studied. Evidence is presented that suggests the carrier action of the compounds is dominated by dispersion forces and that interaction between dye and the carrier in the fiber has been detected.
Swelling and glass transition relations for epoxy matrix material in humid environments
Authors: McKague E. Lee , Reynolds Jack D. , Halkias John E. 
Published: April 2003

AbstractAn experimental investigation has established coherent data sets describing effects of moisture absorption upon swelling and glass transition of an epoxy resin. Equilibrium moisture absorption levels and resultant swelling can be represented by power law functions of relative humidity and quantity of absorbed moisture, respectively. Depression of glass transition temperature is shown to be described by a relationship derived from free‐volume theory.
Water transport through reconstituted collagen hollow‐fiber membranes
Authors: Viswanadham R. , Agrawal Dinesh C. , Kramer Edward J. 
Published: April 2003

AbstractThe hydraulic permeability κ of reconstituted collagen hollow‐fiber membranes has been determined from measurements of the volumetric flow rate of aqueous solutions through the membrane for various pressure differences across the membrane. Increasing the ultraviolet crosslinking time during manufacture of the membrane markedly decreases κ, whereas decreasing the pH of the aqueous solution increases κ. Applying a tensile strain of only 10% along the fiber axis decreases κ approximately fivefold. These results are in good agreement with those expected from a recent model of the membrane structure in which collagen fibrils, oriented preferentially along the hollow‐fiber axis, bend between crosslinks to accept water in a pore structure. If the average fibril volume fraction and diameters are known, estimates can be made of κ. These estimates, based on direct small‐angle x‐ray scattering measurements of fibril diameters, are in good agreement with the measured κ values.
Graft copolymerization of vinyl monomers onto modified cotton. IX. Hydrogen peroxide–thiourea dioxide redox system induced grafting of 2‐methyl‐5‐vinylpyridine onto oxidized celluloses
Authors: Hebeish A. , El‐Rafie M. H. , Waly A. , Moursi A. Z. 
Published: April 2003

AbstractCotton cellulose was independently oxidized with potassium periodate, potassium dichromate‐sulfuric acid, and potassium dichromate–oxalic acid, and the resulting oxidized celluloses were further modified by treatment with chlorous acid or sodium borohydride. The various modified celluloses so obtained were grafted with 2‐methyl‐5‐vinylpyridine using a thiourea–dioxide–H2O2 redox system. It was found that the initiation characteristics of the cellulose samples vary widely with the oxidizing agent used. Further modification of the oxidized celluloses by treating them with chlorous acid enhances considerably their susceptibility toward grafting. The opposite holds true when these oxidized celluloses were modified by sodium borohydride treatment. Excluding thiourea dioxide from the polymerization system offsets grafting onto cotton cellulose while considerable grafting takes place on the various oxidized celluloses and their further modified samples. The work was also extended to study the factors which affect the graft uptake, homopolymer formation, and total conversion. In addition, the reactions involved in initiation of grafting were elucidated.
Ozone treatment of water‐soluble polymers. III. Ozone degradation of polyacrylamide in water
Authors: Suzuki Junzo , Iizuka Shinobu , Suzuki Shizuo 
Published: April 2003

AbstractPolyacrylamide (MW 350,000) was ozonized at pH 2 and pH 10 buffer solution. There was little ozonization at pH 2, but at pH 10 the COD and the viscosity of the solution decreased upon ozonization, and a linear relationship existed between the ozone consumed and the number of breaks calculated from the viscosity. This relationship apparently indicated that 45 molecules ozone were consumed for one cleavage of the polymer chain. Such random cleavage was confirmed also by the observation of molecular weight distribution by means of gel filtration chromatography. The amide group decreased scarcely by the ozonization, while a small amount of aldehyde was observed in the ozonized solution. No remarkable change was observed in the IR spectra of the ozonized sample, except for a weak absorption band at 1725 cm−1 which arose from the carbonyl of aldehyde or ketone. Although no variation was observed in the 13C NMR spectra either, a strong absorption peak at 266 nm appeared in the UV spectra of the ozonized solution and increased with the ozonization time. This phenomenon was presumed to be due to the formation of a certain ring structure between the amide group and the small amount of ketone produced in the main chain. However, the details of the ozonization mechanism could not be ascertained.
Comparison of similar narrow molecular weight polystyrenes
Authors: Plazek Donald J. , Agarwal Pawan 
Published: April 2003

AbstractDiscrepancies between the level of the viscosity at 200°C of the Dow series of polystyrenes and another narrow molecular weight distribution polystyrenes have been pointed out by Toosi, Porter, and Johnson in 1969. Penwell and Graessley have shown in 1974 that over a wide range in temperature one member of this series, S109, has a significantly lower viscosity than samples of similar molecular weight from other sources. Fetters has established the presence of high molecular weight tails in several of the much studied series. The investigation being reported here reveals the effect of the high molecular weight tail in the viscoelastic behavior of the S109 in the terminal zone of response. In addition, it is shown by an enhanced rate of creep in the glass to rubber‐like dispersion that the glass temperature of the S109 is depressed by about 4°C.
Degradation of aqueous poly(acrylic acid) and its sodium salt solutions by high‐speed stirring
Authors: Nakano Akihiko , Minoura Yuji 
Published: April 2003

AbstractPoly(acrylic acid) and 100% neutralized poly(acrylic acid) in pure water were stirred at 30°C at 30,000 rpm with a T. K. Homomixer at polymer concentrations ranging from 2% w/v to 0.0025% (25 ppm) for 2 hr to investigate the effect of polymer chain conformation on chain scission by high‐speed stirring. After 2 hr of stirring at low concentration, intrinsic viscosity measured in 1.00 mole/1. NaCl solution at 30°C for 100% neutralized polymer was lower for the polymer which was stirred after 100% neutralization than for the one before 100% neutralization, showing that expanded polymer chains were more easily ruptured.
Indentation studies in aluminum‐filled epoxies
Authors: Theocaris P. S. , Paipetis S. A. , Papanicolaou G. C. 
Published: April 2003

AbstractA class of aluminum‐filled epoxy composites were subjected to indentation tests over a wide temperature range. The tests were carried out under constant load and continuously varying temperature. The effect of aluminum content, applied load, and adhesion efficiency between matrix and aluminum particles on the indentation behavior was studied. Measured indentation values were found to lie within limits predicted theoretically.
Morphological zones and orientation in injection‐molded polyethylene
Authors: Tan Victor , Kamal Musa R. 
Published: April 2003

AbstractThe properties of injection‐molded plastics parts are affected by resin properties, molding geometry, and molding conditions. The thermomechanical history, which results from the interactions between resin properties and molding conditions, controls the development of microstructure within the article. In turn, the microstructure controls the ultimate behavior of injection‐molded parts. Morphology and orientation and their distributions are among the most important microstructural characteristics affecting the ultimate mechanical and physical behavior of molded articles. This work summarizes some of the results of an extensive experimental and theoretical program to study the factors affecting the development of morphology and orientation in injection‐molded polyethylene. In particular, various experimental techniques are employed to study the distribution of morphology and orientation in simple moldings and to relate these characteristics to resin properties and molding variables. Furthermore, an attempt is made to employ mathematical models to explain and predict some of the observed phenomena especially in relation to the distribution of morphological zones in the molding. It appears that model predictions are in good agreement with experimental results.
Plasma‐deposited polymer films. III. The effects of gamma irradiation
Authors: Oberbeck W. F. , Mayhan K. G. , James W. J. 
Published: April 2003

AbstractThe results of a study of irradiated and unirradiated samples of polymers prepared by plasma polymerization in an inductively coupled radiofrequency (rf) reactor using infrared, elemental, thermogravimetric, and ESR analyses and density and refractive index measurements are presented. The plasma‐formed polymers studied include polypropylene, poly(ethylbenzene), poly(methyl methacrylate), poly(tetrafluoroethylene), poly(chlorotrifluoroethylene), and poly(trimethylchlorosilane).