bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cellulose acetate: Interactions with aqueous phenol and a transition temperature of about 20°C
Authors: Murphy Andrew P. 
Published: April 2003

AbstractSorption of aqueous phenol onto powdered cellulose acetate can be described with the Langmuir equation at phenol concentrations below 0.10M. Unacetylated hydroxyl groups are probably the primary sites where phenol hydrogen bonds. As the phenol concentration is increased (> 0.13M), additional hydrogen bonding may occur with the carbonyl oxygens on the primary acetate groups, followed by secondary acetates and the beta glucosidic oxygens. Sorption at higher concentrations shows a negative slope for the Langmuir equation, perhaps caused by crowding and partial blocking of sites. Extrapolations to higher phenolic concentrations using the equation from the negative slope isotherm and plotting N versus °C reveal two lines with a point of intersection at 0.77M. Because of the increase slope above 0.77M, cellulose acetate may be dissolving in phenol. At concentrations below 0.10M, two processes were identified using a Van't Hoff plot (9.33 ± 0.30) × 103 and (−1.36 ± 0.18) X 103 J/mol. The initial moisture present in the polymer appears to be an important experimental variable and a transition temperature of 20.1 ± 0.2°C, probably due to polymer swelling, is reported.
Gas transport in poly(alkoxyphosphazenes)
Authors: Hirose Takuji , Mizoguchi Keishin 
Published: April 2003

AbstractThe permeability of four structurally related poly(alkoxyphosphazenes), three isomers of poly(dibutoxyphosphazenes) (PBuP), and poly(di‐neopentyloxyphosphazene) (Pneo‐PeP), to 13 gases has been determined by the time‐lag method. Systematic variations in chemical structure have shown a large effect of side chains on permeabilities and permselectivities. The permeability of poly(di‐n‐butoxyphosphazene) (Pn‐BuP) is of the order of 10−8 cm3 (STP) cm/(cm2 s cmHg) for many gases, and the value for a large gas is higher than that for a smaller one. For small gases such as He and H2, poly(di‐sec‐butoxyphosphazene) (Ps‐BuP) is as permeable as Pn‐BuP, but its diffusivities for larger gases such as Xe and C3H8 are about one order lower than those of Pn‐BuP. While the permselectivity of Pn‐BuP is determined by the solubility, that of Ps‐BuP depends on both the diffusivity and solubility factors. The property of poly(diisobutoxyphosphazene) (Pi‐BuP) is intermediate between them. These polymers are constitutionally identical, and the only difference is the arrangements of carbons in the side groups. As the side chains become bulky, the permeability decreases, whereas the permselectivity increases. Further decreases of diffusivity and then permeability are observed for Pneo‐PeP, whose side groups have one more methyl group than does Pi‐BuP. But the solubility data are not much different from other three polymers and the diffusivity factor becomes more significant in permselectivity. The diffusivity depends on the polymer structure much more than does the solubility. The relationships between chemical structure and gas diffusivity and solubility are discussed.
Interpenetrating polymer networks of castor oil polyester and poly(methyl methacrylate)
Authors: Murthy C. N. , Patni M. J. , Deshpande D. D. , Kudchadker A. P. , Mehta M. H. , Ankleshwaria B. V. 
Published: April 2003

AbstractThe physical and mechanical properties of interpenetrating polymer networks (IPNs) and semi‐I IPNs of the castor oil polyester network and poly(methyl methacrylate) were investigated. In the semi‐I IPNs, the second component was a copolymer of poly(methyl methacrylate) and polystyrene (PS) or poly(methyl methacrylate) and poly(n‐butyl acrylate) (PnBA). The dynamic mechanical properties indicated the semi‐I IPNs to be more compatible than the IPNs. The degree of molecular mixing was higher than that for IPNs. The impact strength showed a gradual increase with the increase in the percentage of PS or PnBA in the copolymer. The effect of the copolymerization of the second component on transparency was investigated. The transparency of the semi‐I IPNs increased with the increasing composition of PnBA, but reduced with the increasing composition of PS. These results are discussed in light of existing theories.
Effect of water in vapor‐phase photografting of vinyl monomers on polymer films
Authors: Kubota Hitoshi , Ogiwara Yoshitaka 
Published: April 2003

AbstractThe effect of water added to monomer being supplied in the vapor phase was investigated in photografting on sensitizer‐coated polymer films at 60°C. A pertinent quantity of water accelerated sharply the photografting irrespective of the nature of monomer (acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, and acrylonitrile), film substrate (low‐density and high‐density polyethylenes, polypropyrene, nylon 6, and polyester), and sensitizer (benzophenone and anthraquinone). Water was found to increase the molecular weight of the grafts, which was studied on acrylonitrile‐grafted nylon 6 film. It was confirmed that water exhibited an accelerating action on photoinduced solution polymerizations of acrylic acid and methyl methacrylate, resulting in an increased molecular weight of the both polymers. These results suggest that the accelerating action of water may result from the restriction of chain termination.
Effect of polycarbonate molecular weight on precrack hysteresis energy in determining its ductile‐brittle transition
Authors: Chang Feng‐Chih , Hsu Hon‐Chun 
Published: April 2003

AbstractThe distinctive ductile‐brittle transition behavior of pseudoductile polymeric materials such as polycarbonate (PC) has been discovered to be closely related to the precrack hysteresis loss energy. The higher molecular weight (MW) PC with higher ductility also results in higher precrack hysteresis energy and therefore greater precrack plastic volume under condition of constant loads. If the precrack plastic volume exceeds a critical value, crack initiation thereafter will propagate within the domain of the plastic zone and results in ductile fracture. The deformation displacement is closely related to the precrack plastic volume, and the critical displacement actually determines the critical plastic volume. The higher molecular weight polycarbonate with higher entanglement density is able to withstand earlier crack initiation more effectively. Toughening plastics, such as rubber modification, is simply the result of delaying or retarding the crack initiation and allows the precrack plastic zone to grow over its critical value. A model of crack criterion based on precrack plastic zone is proposed to interpret the ductile‐brittle transition phenomenon.
The relationship between the physico‐mechanical properties and the filler concentration in the HD polyethylene‐dispersed filler system
Authors: Bozveliev L. G. , Kosfeld R. , Uhlenbroich Th. 
Published: April 2003

AbstractThe relationship of 10 basic physico‐mechanical properties and the concentration of the filler is investigated through narrow filling intervals of seven different composite series containing various types of HD polyethylene and different grades of kaolin. A variety of mixing techniques for the preparation of the composites is used, and testing is carried out by applying different techniques and conditions. The investigations show that, in all cases when an identical mixing technique is applied for a given series of composite formulations, the relationship linking the physico‐mechanical and dynamic‐mechanical G′, G″, and tan δ properties with the concentration of the filler is not a monotonous curve, and displays a multiextermal character. We propose as one possible explanation that a periodic change in the free volume and the content of crystal polyethylene phase exists, as a function of the filling. The nonmonotonous character of the changes of properties is related to the proposed mechanism for the change of the physical structure of composites, which are composed of filler particles coated with n monolayers of polyethylene crystallites, when, as filling continues, periodically new types of filler particles are formed. The nonmonotonous character of the relationship between the properties and the concentration of the filler should be taken into consideration when these relationships are approximated or expressed in a mathematical‐analytical form, especially when high amounts of fillers (more than 20 vol %) are used.
The effect of polymer additives on the performance of a two‐roll coater
Authors: Kang Yao‐Ting , Lee Kwong‐Yang , Liu Ta‐Jo 
Published: April 2003

AbstractThe effect of polymer additives on the performance of a two‐roll coater has been examined experimentally. The coater consists of a rigid steel roll and a deformable roll with polyurethane surface. Newtonian coating solutions and solutions with polymer additives were used as test fluids. Both forward and reverse coating operations were studied. It was found that for the forward coating operation, the shear‐thinning behavior of the polymer solutions can reduce the coating thickness, but the fluid elasticity can increase the coating thickness significantly and can also destabilize the coating flow. For the reverse coating operation, a small amount of polymer additives can effectively increase the wipe ratio.
Effect of new additives on the ultrasonic attenuation and mechanical properties of styrene–butadiene rubber
Authors: Aziz A. W. , Younan A. F. , Eid A. M. 
Published: April 2003

AbstractThe change in attenuation of longitudinal ultrasonic waves has been measured as a function of frequency and temperature for styrene–butadiene‐rubber (SBR) mixed with Ismacorr 141 as plasticizer and antioxidant. Analysis of the results showed relaxation processes and the activation energies for these processes were calculated and found to be related to the plasticization of samples. Also the velocity of the ultrasonic longitudinal waves through different samples was measured. The effect of Ismacorr 141 on the physical and mechanical properties of SBR was also studied.
Studies on the preparation and characterization of poly(4‐vinylpyridine) microgel. I. Preparation with polymer emulsifier
Authors: Ma Guang Hui , Fukutomi Takashi 
Published: April 2003

AbstractPoly(4‐vinylpyridine) (P4VP) microgels with a narrow size distribution have been prepared by a special emulsion polymerization method. This is to say that P4VP, to which cation and double‐bond were introduced with iodomethane and chloromethylstyrene, by quarternization reaction was used as a polymer emulsifier. Divinylbenzene was used as a crosslinking agent. It was found that the microgel became larger with the increase in monomer concentration, and became smaller and softer with the enhancing emulsifer/monomer ratio. Microgels, with the diameter of between 70–700 nm, were obtained by varying the monomer concentration from 1.0 wt % to 5.0 wt %, and by varying the emulsifier/monomer (unit/unit) ratio from 0–10.0 mol %. Compared with conventional emulsion polymerization with surfactant or hydrophilic monomer, this method provides an advantage in that monoingredient microgels can be obtained.
Effect of catalyst on the curing of tetrafunctional epoxy resin formulations
Authors: Jagadeesh K. S. , Siddaramaiah  
Published: April 2003

AbstractCure kinetics of tetraglycidyl 4,4′‐diaminodiphenyl methane resin formulations with diaminodiphenylsulfone as hardener and borontrifluoride‐ethylamine adduct as accelerator has been studied by differential scanning calorimetry (DSC) technique both dynamically and isothermally. The DSC scans show multiple exotherm peaks, indicating the complex nature of reaction. The curing exotherms obtained have been analysed to derive the kinetic parameters associated with the curing process. The heat of reaction shows a decreasing trend with increasing catalyst concentration.
Polyamine‐modified urea‐formaldehyde resins. II. Resistance to stress induced by moisture cycling of solid wood joints and particleboard
Authors: Ebewele Robert O. , River Bryan H. , Myers George E. , Koutsky James A. 
Published: April 2003

AbstractThe objective of this study was to improve the durability and stability of urea‐formaldehydebonded wood products by decreasing the internal stress developed during resin cure and by improving the ability of the cured system to withstand cyclic stresses. Urea‐formaldehyde resins were modified by (i) incorporating urea‐terminated di‐ and trifunctional flexible amines into the resin structure, (ii) curing the resins with the hydrochloride derivatives of some of these amines (in place of ammonium chloride), or (iii) using both processes. The cyclic stress resistance of solid wood joints and the internal bond strength and thickness swell of particleboards made with these resins were compared with these properties in joints and particleboards made with an unmodified resin and a commercial urea‐formaldehyde resin. The strength of joints and the internal bond strength of particleboards made with resins modified with urea‐terminated hexamethylenediamine, bishexamethylenetriamine, and poly(propylene oxide) triamine at modifier contents of 13, 16, and 28 wt %, respectively, showed excellent stability even after repeated wet‐dry cycles. Similar stress resistance was shown by wood joints and particleboards bonded with the unmodified resin cured with the hydrochloride salts of hexamethylenediamine and triethyleneaminetriamine. In contrast, solid wood joints and particleboards bonded with the unmodified resin cured with ammonium chloride showed lower resistance to cyclic stress. Particleboards that possessed good cyclic stress resistance also showed less thickness swell.
Evaluation of the area under linear loss modulus‐temperature curves
Authors: Fay J. J. , Thomas D. A. , Sperling L. H. 
Published: April 2003

AbstractThe area under the linear loss modulus‐temperature curves, LA, has been shown to be related to the chemical composition of the material. In addition, it can be significantly affected by morphology in multicomponent polymer systems. To characterize LA quantitatively, base‐line corrections for instrumental contributions to LA were evaluated by several different methods and the results compared. In some instances, the calculation method affects only the LA magnitude, while general trends are unchanged; whereas in others, qualitative differences also become important. Not all of the methods described can be utilized universally. However, a straight‐line‐type of base line, similar to that which is used in infrared spectroscopy and differential scanning calorimetry, provides a widely applicable means of quantifying the loss area.
A polymeric amine–copper(II) complex as catalyst for the hydrolysis of 1,2,2‐trimethylpropyl methylphosphonofluoridate (soman) and bis (1‐methylethyl) phosphorofluoridate (DFP)
Authors: Hammond Philip S. , Forster Jeffry S. 
Published: April 2003

AbstractThe Cu (II) complex of poly‐4‐vinylpyridine, quaternized with 19 mol % ethyl bromide and 36 mol % 4‐chloromethyl‐4′‐methyl‐2,2′‐bipyridine, was examined as a catalyst for the hydrolysis of the toxic organophosphorous compounds bis (1‐methylethyl) phosphorofluoridate (1, Registry no.: 1, 55‐91‐4; 2, 96‐64‐0.
DFP) and 1,2,2‐trimethylpropyl methylphosphonofluoridate (2, soman). Studies were carried out at 25.0 and 37.0°C for both substrates in MOPS buffer at pH 7.0. In the presence of 7.31 × 10−3 M catalyst at 25.0°C, soman is hydrolyzed with a first‐order rate constant of 0.019 min−1 (t1/2 = 37.5 min), whereas DFP hydrolyzes with a rate constant of 0.011 min−1 (t1/2 = 63.8 min). For soman, this represents a 14‐fold increase over the uncatalyzed rate in the same buffer. Other studies examined the effect of a strongly sorptive polymeric resin on catalysis by this copper‐containing polymer and found a dramatic decrease in the hydrolysis rate of soman in the presence of the polymeric sorbent.
Effect of crosslinking agents on the structure and properties of polyurethane millable elastomer composites
Authors: Paulmer R. D. A. , Shah C. S. , Patni M. J. , Pandya M. V. 
Published: April 2003

AbstractA study of the effect of crosslinking agents on the structure and properties of the millable polyurethane (PU) elastomer is reported here. Effects of the conventionally used dicumyl peroxide (DCP) and tolylene disocyanate dimer (TDID) on the curing characteristics, mechanical properties, and relative thermal stabilities of the PU composites have been compared. Use of X‐ray diffraction as a supportive evidence helps in understanding the nature of crosslinking. The mixture of DCP and TDID is also evaluated as crosslinking agents. A dramatic improvement in the mechanical properties and thermal stability is observed because of the mixed type of crosslinking obtained by the combined use of DCP and TDID. Effect of carbon black loading shows an increase in the mechanical strength with a decrease in the elongation. The results obtained from various properties measurements have been satisfactorily explained with a general model of crosslinking.
The thermal aging of filled polyurethane
Authors: Trong‐Ming Don , Chiu Wen‐Yen , Hsieh Kuo‐Huang 
Published: April 2003

AbstractThermal aging and strain endurance experiments on a filled rubber were performed at several temperatures. The rubber was polyurethane (PU) made from hydroxyl‐terminated polybutadiene (HTPB) with 4,4′‐diphenyl methane disocyanate (MDI). The filler was sodium chloride. The mechanical properties, glass transition temperature, dynamic viscoelasticity, and chemical structures were investigated for filled and unfilled PU under an aging period at 60 and 80°C and 50% relative humidity. We found that at 60°C the chemical structures of the filled and unfilled rubbers had no changes in 30 days during aging. But moisture had some effects on the filled PU and changed its mechanical properties. At 80°C, the chemical structures of the filled and unfilled PU had changed due to the thermal oxidation of polybutadiene in aging. The deterioration was more apparent for the filled rubber than for the unfilled. The prestraining would dewet the filler from the samples and it increased the voids.
Swelling of poly(glycidyl methacrylate) gel particles by organic solvents
Authors: Fukuda Takeshi , Kohara Noriyuki , Onogi Yoshihiko , Inagaki Hiroshi 
Published: April 2003

AbstractFine particles of poly(glycidyl methacrylate) (PGMA) were prepared by suspension polymerization and crosslinked via the ring‐opening reaction of the epoxide group with formic acid. A fraction of the spherical gel particles averaging about 70°m in diameter was examined under an optical microscope with its swelling behavior in a number of solvents. Equilibrium degrees of swelling were established with accuracy to show that this polymer gel has rather unusual affinities for solvents: (i) It is swollen (and, without the crosslinks, soluble in most cases) in many types of solvents, (ii) it cannot be represented by a single value of solubility parameter, and (iii) it is not swollen at all in water nor in aliphatic alcohols, in spite of the presence of hydroxy groups in the chain.
Castor oil based UV‐curable polyurethane‐acrylate interpenetrating networks
Authors: Homan James G. , Yu Xue‐Hai , Connor Timothy J. , Cooper Stuart L. 
Published: April 2003

AbstractCastor oil was reacted in varying ratios with β‐isocyanatoethyl methacrylate to form a liquid urethane–methacrylate prepolymer. This prepolymer was then cured using ultraviolet radiation to form a series of base polymer networks or using various methacrylates to form conetworks. By swelling the base networks with the appropriate methacrylate monomers, semi‐ and full interpenetrating networks (IPNs) were prepared with similar compositions. All of the materials formed transparent films. Results of swelling experiments, dynamic mechanical analysis, differential scanning calorimetry, and small angle x‐ray scattering are discussed.
Accelerated failure of bisphenol‐A polysulfone during electron beam irradiation under an applied stress
Authors: Hill David J. T. , Lewis David A. , O'Donnell James H. 
Published: April 2003

AbstractBisphenol‐A polysulfone, poly(oxy‐1,4‐phenylenesulfonyl‐1,4‐phenyleneoxy‐1, 4‐phenyleneisopropylidene‐1,4‐phenylene), PSF (I) showed greatly reduced resistance to electron beam irradiation when subjected simultaneously to an applied tensile stress. The creep rate increased, and the time (dose) to failure of the sample decreased with increasing stress. The failure strain was constant for different applied stresses. Air, oxygen, and moisture caused decreases in radiation resistance compared with a dry nitrogen atmosphere. Increasing the irradiation temperature from 0 to 90°C resulted in substantially decreased radiation resistance.
Study on modified phenolic resin. II. Modification with p‐hydroxyphenylmaleimide/styrene copolymer
Authors: Matsumoto A. , Hasegawa K. , Fukuda A. , Otsuki K. 
Published: April 2003

AbstractThe improvement of heat resistance and mechanical properties of phenolic resin was examined with the blend of novolac and copolymers prepared from p‐hydroxyphenylmaleimide (HPMI) and styrene.Copolymers of HPMI and styrene with various molecular weights were synthesized. Glass transition (Tg) and thermal decomposition temperatures of the copolymers were measured by differential scanning calorimetry (DSC) and thermogravimetry (TG), respectively. The miscibility of the copolymers with novolac was examined by DSC.It was found that the copolymers had a good heat resistance and a good miscibility with novolac. Molding compounds were prepared by hot roll‐kneading of mixtures that involved novolac, copolymer, hexamethylenetetramine (hexamine), and glass fiber. It was found that the test pieces prepared by transfer molding from the molding compounds showed a good heat resistance and better mechanical properties than phenolic resin modified with HPMI homopolymer.
Enhanced enzymolysis of never‐dried cotton fibers belonging to different species
Authors: Bhatawdekar Shaila P. , Sreenivasan S. , Balasubramanya R. H. , Sundaram V. 
Published: April 2003

AbstractEnzymolysis of cotton cellulose in their never‐dried state, belonging to all the four cultivated species of cotton, was carried out with the enzyme derived from penicillium funiculosum F4. Hydrolysis to reducing sugars was almost complete for all the cottons in 6 h, though glucose percentage varied. X‐ray characterizations of the residues obtained, which were both after enzyme and acid hydrolysis, showed significant differences between both hydrolyses, as well as differences in the behavior of different cotton fibers towards enzyme action. These differences have been attributed to the different structural organization of cellulose in the secondary cell wall of cotton fibers.
Fabrication methods for latex‐based elastomer composites reinforced with long discontinuous fibers
Authors: Epstein Mikael , Shishoo R. L. 
Published: April 2003

AbstractRubber‐ or elastomer‐based composites have so far been reinforced with randomly dispersed staple fibers of very short lengths. In this work, methods have been devised to produce composites where the dispersed fibers have considerably greater lengths. This achievement was possible by applying the rubber or elastomer as latex when mixing it with the fibers. As compared with earlier processes, the viscosity is considerably lower, thus permitting easier mixing so that longer staple fibers can readily be used.
Some observations on morphology of anhydride‐modified polystyrene
Authors: Chatterjee S. , Biswas M. 
Published: April 2003

AbstractFriedel–Crafts acylation reaction between polystyrene and phthalic anhydride in the presence of AlCl3 has been performed in two different solvents, 1,2‐dichloro ethane and nitro‐benzene. The morphology of the condensate prepared in 1,2‐dichloroethane has revealed the participation of 1,2‐dichloroethane, i.e., a competitive Friedel–Crafts alkylation reaction.