bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase behaviors and film properties of dispersions and coatings containing associative and conventional thickeners
Authors: Ma Zeying , Lundberg David J. , Roberts Stacy , Glass Edward J. 
Published: April 2003

AbstractPhase‐separation behaviors of latex dispersions, using commercial latices of three different median sizes, and pigmented coatings are examined. Both the dispersions and pigmented coatings at a 0.32 volume fraction of total dispersed phase were thickened with water‐soluble polymers, with and without surfactant hydrophobes. Latex dispersions thickened with water‐soluble polymers without hydrophobe modification follow the phase‐separation behavior described by the volume restriction flocculation (VRF) concept (i.e., molecular weight of the thickener or particle size of the latex). This is surprising since commercial latices contain a variety of surface‐stabilizing moieties, in addition to surfactant. Latex dispersions thickened with commercial and model hydrophobically modified ethoxylated urethane (HEUR) polymers do not follow the phase‐separation behavior predicted by the VRF concept. The lack of correlation of phase behavior with latex median size in HEUR‐thickened formulations led to an examination of four secondary thickeners, noted for providing high viscosities at low shear rates. With an all‐acrylic, large median‐size latex, the combinations of commercial HEURs with secondary thickeners are effective in eliminating phase separation; only partial reduction in phase separation is observed with a vinyl acetateacrylic large‐particle latex. The influence of HEUR/secondary thickener blends on the film properties also is discussed. © 1993 John Wiley & Sons, Inc.
Thermo‐sensitive swelling behavior in crosslinked N‐isopropylacrylamide networks: Cationic, anionic, and ampholytic hydrogels
Authors: Yu Hua , Grainger David W. 
Published: April 2003

AbstractCrosslinked polymer networks of N‐isopropylacrylamide (NiPAAm) containing small amounts of either anionic or cationic comonomers, or mixtures of both were fabricated and characterized in terms of their aqueous swelling and critical behavior. These gels demonstrate critical transition temperatures in aqueous media between a highly solvated, swollen gel state and a collapsed, dehydrated network over temperature ranges comparable to that of pure NiPAAm, with modifications of gel critical points and respective temperature ranges dependent upon comonomer type and content. Copolymer gel swelling ratios are significantly larger than those reported for pure homopolymer NiPAAm gels, even when only 0.5 mol % of comonomer is incorporated. At temperatures exceeding the collapse transition point, all copolymer gels collapse to a state of nearly complete dehydration, demonstrating short‐time collapsed‐state swelling ratios far lower than those of pure NiPAAm networks. Collapse kinetics for the ionomeric gels are much more rapid than those of pure NiPAAm, achieving collapse state equilibrium on time scales of seconds. Swelling behavior as a function of pH, buffer type, ionic strength, crosslinking, and temperature is detailed over a range of copolymer compositions. © 1993 John Wiley & Sons, Inc.
Physical properties of silk fibers grafted with a binary mixture of styrene and n‐butyl methacrylate
Authors: Tsukada Masuhiro , Freddi Guiliano , Monti Patrizia , Bertoluzza Alessandro 
Published: April 2003

AbstractThe mechanical and physical properties, as well as the crystalline structure of silk fibers grafted with a binary mixture of styrene (St) and n‐butyl methacrylate (BMA) were studied as a function of the weight gain. The size of the fibers increased linearly with the extent of grafting. The strength, the elongation at break, and the tensile modulus decreased with increasing weight gain, but the breaking load remained almost unchanged. The difference among the tensile properties measured in dry and wet states decreased beyond weight gain of 50% because of the hydrophobic properties of grafted silk fibers. The thermal behavior was determined by differential scanning calorimetry (DSC), thermomechanical analysis (TMA), and thermogravimetric analysis (TGA) measurements. Silk fibers attained a higher thermal stability as the amount of loaded polymer increased. The thermally induced molecular movement of St/BMA‐grafted silk fibers was enhanced as judged by shifting the onset and the position of the dynamic loss modulus (E″) peak to lower temperature when the weight gain increased. X‐ray diffraction curves demonstrated that the crystalline structure of silk fibers remained unchanged regardless of the St/BMA grafting. © 1993 John Wiley & Sons, Inc.
Polypropylene–Carbon black interaction in conductive composites
Authors: Petrović Zoran S. , Martinović Bratislav , Divjaković Vladimir , Budinski–Simendić Jaroslava 
Published: April 2003

AbstractInteraction between polypropylene matrix and carbon black was examined by measuring physical, mechanical, and electrical properties. It has been shown that presence of carbon black influences the morphology and crystallinity of the matrix. Strong interaction was observed directly by electron microscopy and indirectly by the rise of the modulus of elasticity. The effect of carbon black on strength and physical properties of the composites is discussed. © 1993 John Wiley & Sons, Inc.
Polymerization of olefins through heterogeneous catalysis. XIII. The influence of comonomer in the solution copolymerization of ethylene
Authors: Jaber Isam A. , Ray W. Harmon 
Published: April 2003

AbstractThe copolymerization of ethylene with highly active TiCl4/MgCl2‐supported catalysts in solution reactors at 185°C and 400 Psig pressure is presented. The performance of these highly active supported catalysts at high reaction temperature is characterized by a high initial rate that decays rapidly within the 10 min polymerization time period. In the presence of hydrogen and a comonomer, catalyst yields up to about 300 kg/g (Ti) are achieved. Kinetic data obtained on the influence of a comonomer, e.g., 1‐octene or 1‐hexene, indicate rate enhancement when used in moderate concentrations. Higher concentrations of comonomer result in a decreasing rate of ethylene consumption. Comonomer/ethylene molar ratios in the range 0–0.827 resulted in comonomer incorporation up to about 2.6 mol % and a small reduction in the polymer molecular weight. © 1993 John Wiley & Sons, Inc.
Interaction of dyes used for foods with food packaging polyamides
Authors: Arvanitoyannis I. , Tsatsaroni E. , Psomiadou E. , Blanshard J. M. V. 
Published: April 2003

AbstractThe effect of pH, temperature, dye concentration, and additives on the adsorption of the dyes FD & C (Food, Drugs & Cosmetics) Blue 1 and Blue 2 upon the polyamides nylon 4–7,9, and 10–12 was studied and a correlation between these parameters and the dye uptake was found. The adsorption kinetics of the dyes on the polyamides were studied and a mechanism based on the interaction of the acid groups of the dyes and the positively charged groups of the polyamides was suggested. © 1993 John Wiley & Sons, Inc.
Vaporization behavior of antioxidant additive BHT in polypropylene by heating
Authors: Hayashi Hiromichi , Matsuzawa Shuji 
Published: April 2003

AbstractThe vaporization behavior by heating of an antioxidant additive 2,6‐di‐tert‐butyl‐p‐cresol (BHT) in polypropylene (PP) was studied. BHT vaporized from PP plates under the stream of air at 70–100°C for 0–3000 min was absorbed to the Tenax GC adsorbent column, and the precentage recoveries of BHT increased linearly with the square root of time: t1/2. There were no considerable differences between the vaporization behavior of BHT by heating under the stream of air and that of nitrogen. BHT does not act as an antioxidant at temperature below 120°C. The percentage recoveries of BHT from PP plates at 90–120°C under a nitrogen stream increased linearly with t1/2 until about 70% of the recovery. At temperature below 80°C, the linear relations still held. The vaporization also proceeded at the temperature below the melting point of BHT. Both the sample thickness and the temperature greatly influenced the vaporization rate of BHT in PP, and the Arrhenius plots of the logarithmus of the specific rate vs. the reciprocal of the absolute temperature at 70–120°C showed an approximately straight line. Triolein coexisted with interrupted BHT vaporization. However, the PP plates containing 0.2 wt % of olive oil showed the same vaporization behavior of BHT as that of the original PP plates free from oils at 80 and 100°C. The decreasing rate of BHT in PP by heating under air obeyed first‐order kinetics. © 1993 John Wiley & Sons, Inc.
Numerical simulation of anomalous penetrant diffusion in polymers
Authors: Wu J. C. , Peppas Nikolaos A. 
Published: April 2003

AbstractThis work introduces a new numerical algorithm that can be used to analyze complex problems of penetrant transport. Penetrant transport in polymers often deviates from the predictions of Fick's law because of the coupling between penetrant diffusion and the polymer mechanical behavior. This phenomenon is particularly important in glassy polymers. This leads to a model consisting of two coupled differential equations for penetrant diffusion and polymer stress relaxation, respectively. If the polymer relaxation is the rate‐limiting step, both the concentration and stress profiles are very steep. A new algorithm based on a finite difference method is proposed to solve the model equations. It features the development of a tridiagonal iterative method to solve the nonlinear finite difference equations obtained from the finite difference approximation of the differential equations. This method was found to be efficient and accurate. Numerical simulation of penetrant diffusion in glassy polymers was performed, showing that the integral sorption Deborah number is a major parameter affecting the transition from Fickian to anomalous diffusion behavior. © 1993 John Wiley & Sons, Inc.
Wood plastic composite using different monomers in presence of additives
Authors: Khan Mubarak A. , Ali K. M. Idriss 
Published: April 2003

AbstractWood plastic composites (WPC) are prepared with low density wood simul under Co‐60 gamma radiation using acrylamide (AM), butyl methacrylate (BMA), and styrene (ST) as the bulk monomers at different compositions with methanol used as swelling agent. The effect of additives, e.g., polyfunctional monomers and oligomers, used by 1% v/v or w/v, on the polymer loading and tensile strength of the composites is investigated. Polyfunctional monomers are N‐vinyl pyrrolidone (NVP), tripropylene gylcol diacrylate (TPGDA), and trimethylol propane triacrylate (TMPTA). Oligomer additives are urethane acrylate (UA), epoxy acrylate (EA), and polyester acrylate (PEA). Increased polymer loading (PL) with enhanced tensile strength (TS) are obtained with the composite. Incorporation of a small amount (1% v/v or w/v) of coadditives like sulfuric acid (H+), lithium nitrate (Li+), copper sulfate (Cu2+), and urea (U) into the impregnating solutions containing the additives has significantly influenced the PL and TS values of the WPC. Though the H+ ion has synergistically enhanced the PL, but it has drastically reduced the TS values. Li+ion has played a good role for the replacement of H+ion. Urea has substantially increased the PL values with relatively small enhancement of TS. Cu2+ ions have retained both PL and TS values of the WPC, which could be used as protective and preservative purposes of the composites. © 1993 John Wiley & Sons, Inc.
The influence of chain configuration and, in turn, chain packing on the sorption and transport properties of poly(tert‐butyl acetylene)
Authors: Morisato A. , Miranda N. R. , Freeman B. D. , Hopfenberg H. B. , Costa G. , Grosso A. , Russo S. 
Published: April 2003

AbstractA series of poly(tert‐butyl acetylene) (PTBA) polymers was prepared with cis contents, as characterized by 13C NMR spectroscopy, ranging from 44% to 100%. The sorption and transport properties of propane in this systematically varied series were determined by a sensitive gravimetric sorption technique. As the cis content of the polymer increased, propane solubility and diffusivity decreased markedly and the d‐spacing, determined by wide angle x‐ray diffraction spectroscopy, decreased monotonically with increasing cis content, suggesting that higher order molecular structure, related explicitly to configurational variations, may strongly influence chain packing in these rigid, glassy materials and, in turn, sorption and transport properties of small molecules in this polymer series. © 1993 John Wiley & Sons, Inc.
On the mechanism of gas transport in rigid polymer membranes
Authors: Hensema E. R. , Mulder M. H. V. , Smolders C. A. 
Published: April 2003

AbstractConventional polymers are compared as gas separation membrane materials with “tailormade” polymers. The increased permeability of the latter are due to their higher free volume available for gas transport. The increased free volume is associated with the rigidity polymer backbone. Free volume is obtained by subtracting the occupied volume, calculated using group contributions from the polymer specific volume. Wide Angle X‐ray techniques are used to obtain average d‐spacings that are interpreted in terms of average intermolecular space, and that are related to permeability data. These highly permeable rigid polymer membranes have high glass transition temperatures. The physical parameters, that is, Tg and the jump in heat capacity (ΔCp), are obtained with Differential Scanning Calorimetry, and are used to obtain an estimation of free volume. A good correlation for a series of random copoly[p, m‐phenylene(4‐phenyl)‐1,2,4‐triazoles] is obtained. A relationship between permeability and a free volume term, which can be estimated from thermodynamic properties, is equally valid for a wide variety of conventional polymers. © 1993 John Wiley & Sons, Inc.
Effect of crystallinity on the kinetics of liquid absorption into poly(ethylene terephthalate)
Authors: Popoola Adeola V. 
Published: April 2003

AbstractDrawn poly(ethylene terephthalate) fibers (D.R. 5 : 1) were treated unrestrained in dimethylformamide and benzaldehyde at 100°C for varying amounts of time. A rapid diffusion of liquids into the polymer occurred, the latter experiencing considerable retention of the absorbed liquids at 60°C. The increase in chain mobility brought about by both the liquids absorbed and the liquid‐induced crystallisation that followed allowed orientation strains existing in the polymer structure to be relieved. This brought about a 20% shrinkage in the polymer and a change in its overall geometry. Subsequently, a sharp drop occurred in the level of liquid retention within the polymer signifying expulsion of liquids from the crystallising domains and ultimately a levelling off (equilibrium) in the weight retention kinetics.However, precrystallisation of the fibers at 200°C for 3 h using dry hot air prior to liquid treatment study at 100°C and retention at 60°C, led to a linear increase in the amount of liquid retained in the polymer as a function of time until an equilibrium was established. The essential feature of the latter liquid retention kinetic is that a plot of the amount of relative liquid retained, that is Mt/M∞ as a function of square root of time, ($\[ \sqrt t \]$) agrees with Fick's standard diffusion process. © 1993 John Wiley & Sons, Inc.
Method of determination of transient and steady‐state conductivity in polyethylene terephthalate ultrathin films
Authors: Thielen A. , Vanderschueren J. , Niezette J. , Feyder G. 
Published: April 2003

AbstractThe determination of transient and/or steady‐state conductivity of polyethylene terephthalate (PET) ultrathin films by means of electrode configurations involving any load or stress imposed on the measuring area during measurement usually leads to anomalous behaviours of the charging current and thus prevents a good evaluation of the electrical properties of the samples. This can be avoided by the use of a two‐electrode system with lateral contacts, to obtain reproducible results without any requirement for previous mechanical, thermal, or electrical treatments (as is often recommended in the literature), and that permits the characterization of industrial films down to 1.5‐μm thick in true storage conditions after production. © 1993 John Wiley & Sons, Inc.
On the gel effect in the presence of a chain transfer agent in methyl methacrylate polymerization and its copolymerization with various acrylates
Authors: Wang X. , Ruckenstein E. 
Published: April 2003

AbstractThe kinetics of methyl methacrylate (MMA) polymerization, and of its copolymerization with various acrylates, at high conversions in the presence of a chain transfer agent, are investigated with a dilatometer over the entire course of reaction. The displacement to higher conversions of the onset of the gel effect in the MMA homopolymerization, in the presence of a chain transfer agent, was determined. Similar information is also provided for the MMA‐acrylate copolymerization systems. An increase in polymerization temperature slightly delays the onset of the gel effect in the MMA‐acrylate copolymerization, but considerably increases the final conversion. The final conversion in copolymerization for a constant concentration of the chain transfer agent is independent of the initiator concentration, but is a function of the polymerization temperature. The reaction time for reaching the limiting conversion in copolymerization is increased with an increasing amount of the second monomer, as well as with an increasing number of carbon atoms in the acrylate used as the second monomer. © 1993 John Wiley & Sons, Inc.
Functional polymers for colloidal application. VIII. Syntheses of anionic and zwitterionic aniline–formaldehyde condensates and their dispersing ability to zwitterionic clay
Authors: Kuo Ping‐Lin , Wey Bih‐Shiuh 
Published: April 2003

AbstractAnionic and zwitterionic aniline–formaldehyde condensates have been synthesized by a methylenation under mild reaction conditions and a reaction with propane sultone. The formation of condensates is characterized by NMR, i.e., the peak of methylene at δ = 3.5−4.0 ppm and the peaks of propylsulfonate at δ = 2.7−3.4 ppm and δ = 1.7−2.2 ppm. The results from GPC show that a longer condensation time increases the degree of polymerization of the condensates. The dispersing properties of the condensates are assessed by the viscosity, scanning electron microscopy (SEM), and adsorption behaviors. N,N‐dimethyl‐N‐(3‐propylsulfonate) anilinium–formaldehyde condensates (DPSAF) with higher molecular weight (DPSAF‐H) show significantly lower apparent viscosities. Comparing the results of SEM and the viscosity method, it can be concluded that, under comparable conditions, a suspension with a lower viscosity is more homogeneously dispersed. The amount of DPSAF‐H adsorbed onto clay is significantly higher than that of PSAF‐H at low concentrations of the dispersant and reaches an optimum after ca. 3 wt %. This result is in parallel with the trend of viscosity. The zwittionic DPSAF promotes their dispersing ability of clay in water due to the existence of the positive and negative charges. The decrease in the amount of adsorbed PSAF‐H with increasing pH can be interpreted by the increased negative charge of the clay, as a result of the decreased interaction between the anionic PSAF‐H and the clay. © 1993 John Wiley & Sons, Inc.
Grafting of polyurethane surfaces with poly(ethylene glycol)
Authors: Freij–Larsson Christina , Wesslén Bengt 
Published: April 2003

AbstractFilms of a commercial poly(ether urethane), Pellethane 2363‐80AE, were prepared through solvent casting from dimethyl formamide. The films were grafted with poly(ethylene glycol) (PEG) by a two‐step procedure. In the first step, the film surfaces were treated with hexamethylene diisocyanate in toluene in the presence of triethylamine as a catalyst. In the second step, PEG 1500 was allowed to react in toluene with surface bound isocyanate groups. It was shown by ATR‐IR, XPS, and contact angle measurements that the grafted surfaces were mainly composed of PEG, and that they were strongly hydrophilic. It was also shown that unreacted PEG was entrapped in the material, which influenced its me‐chanical and thermal properties. Extraction of the films with toluene eliminated the entrapped PEG, and the hydrophilicity as well as the PEG coverage of the surface decreased. However, a subsequent treatment with aqueous NaCl solution induced a molecular restructuring of the surface, increasing the amount of grafted PEG at the surface to a value close to the original one. © 1993 John Wiley & Sons, Inc.
Toughening of epoxy resins by modification with dispersed acrylate rubber for electronic packaging
Authors: Ho Tzong‐Hann , Wang Chun‐Szhan 
Published: April 2003

AbstractDispersed acrylate rubbers were used to improve the toughness of cresol‐formaldehyde Novolac epoxy resin cured with phenolic novolac resin for electronic encapsulation application. The effect of the alkyl group of the acrylate monomer on the phase separation of resultant elastomers from epoxy resin was investigated. The dispersed acrylate rubbers effectively improve the toughness of cured epoxy resins by reducing the coefficient of thermal expansion (CTE) and flexural modulus, while the glass transition temperature (Tg) was hardly depressed. Electronic devices encapsulated with the dispersed acrylate rubber‐modified epoxy molding compounds have exhibited excellent resistance to the thermal shock cycling test and have resulted in an extended device use life. © 1993 John Wiley & Sons, Inc.
Biocidal polymers active by contact. I. Synthesis of polybutadiene with pendant quaternary ammonium groups
Authors: Hazziza–Laskar J. , Nurdin N. , Helary G. , Sauvet G. 
Published: April 2003

AbstractHydroxytelechelic polybutadienes carrying covalently bound quaternary ammonium salts were successfully synthesized in three steps. The first one was the preparation of 1‐(N, N‐dimethylaminopropyl) 1,1,3,3‐tetramethyldisiloxane (M′2A) by hydrosilylation. The addition occurred mainly in the terminal position of the double bond, but isomers were formed in small proportion (an isomer resulting from an inverse addition and an isomer resulting from an isomerization of the double bond). The proportion of these isomers increased with the concentration of catalyst (H2PtCl6). Similar results were obtained with a Pt (0)‐di‐vinyltetramethyldisiloxane complex (Pt,DVDS). The second step was the grafting of M′2A onto the 1,2‐units of a hydroxytelechelic polybutadiene by hydrosilylation. The yield of the reaction was higher than 90% and the OH functionality decreased slightly. Here again, different platinum catalysts were compared: initial rates were higher with Pt,DVDS, but the final yields were better with H2PtCl6. The last step was the quaternization of the pendant tertiary amino groups in methanol with alkyl bromides from C8H17Br to C16H33Br. The yield of the reaction was higher than 90% and the OH functionality was not modified. © 1993 John Wiley & Sons, Inc.