bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of interfacial tensions for latex particles
Authors: Durant Yvon G. , Sundberg Donald C. , Guillot J. 
Published: April 2003

AbstractThe possibility of measuring in situ the interfacial tension at the monomer‐swollen polymer‐water interface of synthetic latices is considered in detail. Experimental measurements of certain liquid or vapor phase properties of the latex can, in principle, yield values of the desired interfacial tension. This technique requires the evaluation and comparison of the Flory–Huggins term and the Morton term of the thermodynamic expression for the chemical potential of the monomer in the latex particle. While each term can be evaluated, it turns out that the relative magnitudes of the two terms are such that unrealistically high precision is required in the experimental measurements for this technique to be useful for obtaining reasonably accurate interfacial tensions. At saturated swelling conditions with highly surface‐active emulsifiers (e.g., sodium dodecyl sulfate), the interfacial tension values obtained have a precision of only about ±50%. The reliability of these approximate values degrades rapidly as one moves away from saturation conditions, so as to render in situ experimental techniques inappropriate for gaining accurate knowledge about the surface energy at the latex particle–water interface at any monomer–polymer ratio. © 1994 John Wiley & Sons, Inc.
Synthesis and characteristics of organic soluble photoactive polyimides
Authors: Ho Bang‐Chein , Lin Yeh‐Sen , Lee Yu‐Der 
Published: April 2003

AbstractSoluble aromatic polyimides with inherent viscosities of 0.23–0.50 dL/g have been synthesized from 2,2‐bis(3‐amino‐4‐hydroxyphenyl) hexafluoropropane (BAPAF) and various aromatic tetracarboxylic dianhydrides. Almost all polyimides were soluble in a wide range of organic solvents, i.e., acetone, m‐cresol, N,N‐dimethylacetamide, N,N‐dimethylformamide, N,N‐dimethylsulfoxide, N‐methyl‐2‐pyrolidone, methyl ethyl ketone, and tetrahydrofuran (except that polyimide deriven from 3,3′,4,4′‐biphenyl tetracarboxylic dianhydride). Synthesized polyimides have a glass transition temperature in a range of 293 to 355°C, showing no appreciable weight loss up to 400°C in both air and nitrogen. These soluble polyimides exhibit high transparency in the UV visible region, with water absorption being between 3.6 to 5.7 wt %. They provide an aqueous base developable positive photoresist system when formulated with diazonaphthoquinone sensitizer. On the other hand, negative photoactive polyimides which are soluble in common organic solvents and optically transparent at a light of 365 nm wavelength, being obtained by reacting these soluble polyimides with methacryloyl chloride. Properties and characteristics of both positive and negative photoactive polyimides have been studied here. © 1994 John Wiley & Sons, Inc.
Selectivity as a function of membrane thickness: Gas separation and pervaporation
Authors: Koops G. H. , Nolten J. A. M. , Mulder M. H. V. , Smolders C. A. 
Published: April 2003

AbstractIn this article, the pervaporation selectivity as a function of the membrane thickness is studied for the dehydration of acetic acid. From this study, it appeared that the selectivity of polysulfone (PSF), poly(vinyl chloride) (PVC), and polyacrylonitrile (PAN) decreases with decreasing membrane thickness, below a limiting value of about 15 μm. However, in the case of gas separation, the selectivity of PSF membranes is independent of the membrane thickness. This phenomenon could not be explained by a difference in membrane morphology, sorption resistance, thermodynamic interaction, or coupling. It is believed that the decrease in selectivity for thin membranes has to be attributed to defects induced during pervaporation. These defects, crazes (and cracks), result from a reduced value of the critical strain, due to sorption of acetic acid/water and stresses between the polymer chains, due to a concentration gradient across the membrane. © 1994 John Wiley & Sons, Inc.
A numerical prediction of peak area in loss factor for polymers
Authors: Ogawa Toshio , Yamada Takuto 
Published: April 2003

AbstractWe tried to correlate the polymer constitutes with the peak areas under tan δ–temperature curves, which are abbreviated as TA (loss tangent area) hereafter. TAs for homopolymers were obtained as the summation of ratio of contributions for functional groups in addition to the constant. TAs for semicrystalline polymers decreased with increase of the degree of crystallinity. Therefore, TAs for semicrystalline polymers were estimated from the ratio of the contribution of functional groups and crystallinity. TAs for copolymers were obtained by adopting the idea of mole ratio. Thus, the predicted values were fairly good in agreement with the measured ones for almost all kinds of linear polymers adapted in this study. © 1994 John Wiley & Sons, Inc.
Transesterification of ethylene vinyl acetate copolymer in a modular intermeshing corotating twin screw extruder with different screw configurations
Authors: Kim Pan Jong , White James L. 
Published: April 2003

AbstractThe transesterification of ethylene‐vinyl acetate (EVA) copolymer to produce ethylenevinyl alcohol copolymer (EVAL) was studied in both a batch reactor and in a modular corotating twin screw extruder with various screw configurations. Increasing the number of left‐handed screw elements and kneading disc blocks increases the extent of conversion under any set of operating conditions. Conversion is increased by decreasing screw speed and reducing throughput. Reactor design models have been developed to represent the modular twin screw extruders. These use a drag flow reactor for screw elements, a continuous stirred tank reactor (CSTR) to represent kneading disc blocks and a plug flow reactor to represent post screw and die regions. Comparison are made with experiment. © 1994 John Wiley & Sons, Inc.
Determination and correction of peak broadening in size exclusion chromatography of controlled rheology polypropylene
Authors: Lederer K. , Beytollahi‐Amtmann I. , Billiani J. 
Published: April 2003

AbstractThe peak broadening in size exclusion chromatography of seven commercial polystyrene (PS) standards with narrow molar mass distribution (MMD) and of 6–9 polypropylene (PP) fractions (M̄w/M̄n = 1.34–2.10) obtained by direct extraction was determined in four different column sets. The dependence of the Gaussian peak broadening parameter, σ2, on the peak elution volume was different for PS and PP. For a commercial grade of controlled rheology PP (CR‐PP) (Daplen PT55) with M̄w/M̄n < 3 it was shown that disregard of the peak broadening effect leads to considerable errors in the MMD at low and higher molar mass and in the polydispersity parameter M̄w/M̄n. The same lot was studied in an Austrian National Research program for its physical propeties in processing and application and in a round‐robin test of IUPAC working party IV.2.2. on molecular characterization of commercial polymers. © 1994 John Wiley & Sons, Inc.
Preparation of anti‐oil stained membrane by grafting polyethylene glycol macromer onto polysulfone membrane
Authors: Iwata Hiroo , Ivanchenko Maria I. , Miyaki Yoshiyuki 
Published: April 2003

AbstractIn this study, anti‐oil stained ultrafiltration membrane was prepared by grafting a polyethylene glycol diacrylate macromer onto a plasma‐activated polysulfone membrane. The macromer formed a hydrate layer which prevented oil in emulsion from directly contacting the membrane surface, thus preventing the oil from staining the membrane. © 1994 John Wiley & Sons, Inc.
Preparation and properties of poly(vinyl acetate)/silica‐gel microhybrids
Authors: Yano Shoichiro , Nakamura Kensuke , Kodomari Mitsuo , Yamauchi Naofumi 
Published: April 2003

AbstractPoly(vinyl acetate) (PVAc) was incorporated into silica gel using the sol–gel process involving tetraethoxysilane (TEOS). In order to prepare silica‐gel microhybrids, two different processes were employed, and the physical properties of the resulting two sets of hybrids were compared. In the first method, PVAc was first mixed with TEOS in an acetone solution and then cured using HCI and H2O. In the second method, an acetone solution of a copolymer composed of vinyl acetate (VAc) and vinyl triethoxysilane (VTES) was first mixed with TEOS and then cured. This copolymer contained 10 mol % of VTES component and was bound covalently to silica‐gel molecules. When comparing the properties of the hybrids, the dynamic modulus, E′, increased with increasing amounts of TEOS over a wide temperature range: −20–120°C. E′ of a hybrid from PVAc was lower than that of a hybrid from the VAc/VTES copolymer. A sharp peak in the loss modulus, E″, of a PVAc hybrid occurred at 40°C, and its position did not change with TEOS content. In contrast, the E″, peak of a copolymer hybrid was broad and its position also shifted to a higher temperature as the TEOS content increased. The tensile strength of a PVAc hybrid increased as the amount of mixed TEOS increased, reaching a maximum of 30 MPa at 50 wt % of TEOS. However, the strength of a copolymer hybrid reached a maximum of 50 MPa at 50 wt % of TEOS. The differences in the physical properties between a PVAc hybrid and a copolymer hybrid arise from the difference in their structure. Organic polymer molecules in a copolymer hybrid combine covalently with silica‐gel molecules through the VTES component, while a PVAc hybrid has no bounding between PVAc and silica‐gel molecules. © 1994 John Wiley & Sons, Inc.
Modifying acrylic‐based superabsorbents. II. Modification of process nature
Authors: Omidian H. , Hashemi S. A. , Askari F. , Nafisi S. 
Published: April 2003

AbstractThis article is devoted to the synthesis, characterization, and modification of acrylic‐based superabsorbents which are synthesized by inverse suspension and solution polymerization techniques. Distilled and saline water absorbency of these hydrogels and the effects of varying process nature on their absorbency characteristics (capacity and rate) are graphically discussed. © 1994 John Wiley & Sons, Inc.
Improvement of jute fiber through ultraviolet‐cured films of urethane acrylate
Authors: Ali K. M. Idriss , Uddin M. K. , Bhuiyan M. I. U. , Khan Mubarak A. 
Published: April 2003

AbstractFormulations were developed with urethane acrylate in combination with different monomers. The role of plasticizers used as coadditives in the formulations was investigated. Physical and mechanical properties of the UV‐cured films were studied. Hessian cloths made with jute fibers were coated with these formulated solutions and cured under UV radiation. Though plasticizers decrease the tensile properties of the UV‐cured films, but they substantially enhance both tensile strength by 80% and elongation of the coated hessian cloths by more than 300%. Uptake of water and moisture at different relative humidity conditions decreases significantly by the hessian cloths when coated with these formulations. © 1994 John Wiley & Sons, Inc.
The thermal and mechanical behavior of poly(ethylene terephthalate) fibers incorporating novel thermotropic liquid crystalline copolymers
Authors: Joslin Scott , Jackson Woodward , Farris Richard 
Published: April 2003

AbstractThis investigation explores the potential of improving the performance of poly(ethylene terephthalate) fibers by incorporating novel thermotropic liquid crystalline copolymers. Fibers were obtained by melt extrusion and the effect of processing conditions, i.e., spinning temperature, stretch ratio, and post treatment evaluated. The fibers were tested for mechanical performance, dimensional instability (shrinkage), and the development of shrinkage stresses. A segmented block copolymer consisting of rigid‐rod, diad, and flexible coil segments was found to improve the performance of poly(ethylene terephthalate) (PET) fibers. At a concentration of 20 wt %, the alternating block copolymer increased the tensile modulus of the fibers by 40% and decreased free shrinkage by 20% compared to neat PET. © 1994 John Wiley & Sons, Inc.
Young's modulus of transcrystallinities in semicrystalline thermoplastic composites
Authors: Zeng Hanmin , Zhang Zhiyi , Zhang Mingqiu , Xu Jiarui , Jian Nianbao , Mai Kancheng 
Published: April 2003

AbstractIn a fiber/semicrystalline polymer system, interphasial transcrystallinities might form between the fibers and the matrix bulk that is composed of spherulites. By using an analogy method, the Young's modulus Et of transcrystallinities in their growth direction was predicted by a well‐known composite modeling theory. It is shown that Et is a function of the polymeric lamellar morphology and crystallinity. It is higher than the Young's modulus Es of the bulk spherulites and positively affects the stiffness of the materials in which the transcrystallinities are formed. The study was focused on poly(ether ether ketone) (PEEK) but with polyethylene (PE) as a comparison. Also, it is demonstrated the various possibilities of the value ET and the ratio ET/Es for different polymeric matrices depending on their lamellar moduli and the amorphous‐phase ones. © 1994 John Wiley & Sons, Inc.
Demonstration of the possible competing effects of oxidation and chain scission in orientated and stressed polypropylenes
Authors: Horrocks A. R. , Valinejad K. , Crighton J. S. 
Published: April 2003

AbstractA series of orientated polypropylene tapes and filaments with differing draw ratio were produced from two parent polymers containing antioxidant systems of different efficiencies. Lengths of tapes and filaments were exposed in air ovens at temperatures up to 130°C under “free” conditions, held at constant length or loaded to differing stress levels for prescribed times or to failure, whichever was earlier. Those morphological effects of oven ageing treatments as are identified from their subsequent tensile behaviors and densities have been reported elsewhere; this study reports the heat flux differential scanning calorimetric (HF‐DSC) observations of unexposed and exposed samples. The HF‐DSC curves of treated samples show, for the postfusion oxidative exotherm for oven‐exposed samples, positive shifts to lower values compared with an unexposed sample, of the extrapolated onset temperature (Ton). Analyses of the tensile, density, and HF‐DSC data suggest that during the initial stages of thermal degradation in air, chain scission competes with oxidation. The rates of the former are enhanced by the application of stress, and scission is considered the origin of the observed deterioration in tensile behavior. Concurrent oxidation during oven exposures affects subsequent autoxidative behavior but has little immediate influence upon the mechanical properties. © 1994 John Wiley & Sons, Inc.
Electropolymrization and physicochemical properties of polypyrrole p‐toluenesulfonate
Authors: Heo Gweon , Lee Dong Hoon , Kim Keu Hong 
Published: April 2003

AbstractPolypyrrole p‐toluenesulfonate (PPTS) polymers were synthesized by the electrochemical technique from 0.2M pyrrole in 0:100, 1:99, 5:95, and 10:90 water/acetonitrile solutions containing 0.1M tetraethylammonium p‐toluene sulfonate (TEATS) as a supporting electrolyte. Following the cyclic voltammetry measurements, the number of electrons involved in the reaction was determined to be unity. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed that the weight loss was most reapid in the temperature range from 533 K to 768 K, and the maximum value of the reaction rate was 0.27 mg/min at 651 K. From the temperature dependence of the electrical condutivity and electron spin responance (ESR) measurement, a small pallaron hopping conduction was suggested for PPTS polymers. © 1994 John Wiley & Sons, Inc.
Synthesis and biocidal activities of polymer. III. Bactericical activity of homopolymer of AcDP and copolymer of acdp with St
Authors: Oh Sang Taek , Ha Chng Sik , Cho Won Jei 
Published: April 2003

AbstractThe bactericidal monomer 2,4,4′‐trichloro‐2′‐acrylolyoxydiphenyl ether (AcDP) was synthesized from 2,4,4′‐trichloro‐2′‐hydroxydiphenyl ether (DP) and acryoyl chloride in the presence of triethylamine in dry THF at 20°C. The synthesized AcDP was indentified by IR, 1H‐NMR, and GC‐MS spectra. The homopolymer of AcDP was obtained using BPO an an initiator in toluene at 70°C. Copolymer of AcDP and styrene (St) was synthesized with a free radical initiator at 70°C. Poly(AcDP) and poly(AcDP‐co‐St) were identified by IR and 1H‐NMR spectra. The maximum weight average molecualr weight (Mw) of poly(AcDP) and poly(AcDP‐co‐St)s were 4100 and 11600, respectively. The monomer reactivity ratios, r1 (AcDP) and r2 (St), determined by the Kelen–Tüdös method, were 0.16 and 0.33, respectively. The glass transition temperature and decomposition temperature of poly(AcDP) were 73.4°C and 348°C, respectively. The bactericidal activities of AcDP, poly(AcDP), and poly(AcDP‐co‐St) were studied using agar dish test. The bactericidal activities of AcDP and its polymers as well as DP agianst Pseudomonas Aeruginosa were very excellent compared to those of control polymers such as poly(St) and poly(ethylene‐co‐vinyl acetate). The bactericidal activities were decreased in the order DP > AcDP > poly(AcDP) > poly(AcDP‐co‐St) Against Pseudomonas Aeruginosa. © 1994 John Wiley & Sons. Inc.
Radical entry into particles during emulsion polymerization of vinyl acetate
Authors: Kshirsagar Ravindra S. , Poehlein Gary W. 
Published: April 2003

AbstractThe entry of free radicals (formed in the aqueous phase) into polymer particles is the subject of the present work. A model has recently been developed based on the postulate that the aqueous‐phase growth of the free radicals to a critical size is the rate‐determining step for entry. An experimental strategy was devised to study this phenomena. Polystyrene latex with a water‐insoluble inhibitor partitioned into the polymer particles was used as seed for secondary polymerization of vinyl acetate. This was done to form and isolate stable oligomers of the critical size. The presence of vinyl acetate oligomers was detected with Fourier transform infrared spectroscopy and thin‐layer chromatography. Fast atom bombardment–mass spectroscopy (MS) was used to determine the molecular weights of the oligomers. Though it was not possible to determine the precise size of the vinyl acetate oligomers formed, the MS results show that the number of monomer units in the oligomers has an upper bound of 12–14. The number of units in the oligomer of critical size was estimated to be about 5–6. These experimental results are quite close to model predictions; thus this work helps in corroborating the model. Additional work is necessary to conclusively validate this model. The experimental strategy used in this work has made it possible to determine the approximate size of oligomers formed in the aqueous phase during emulsion polymerization. © 1994 John Wiley & Sons, Inc.
A survey of polyvinylphenol blend miscibility
Authors: Landry M. R. , Massa D. J. , Landry C. J. T. , Teegarden D. M. , Colby R. H. , Long T. E. , Henriches P. M. 
Published: April 2003

AbstractThe effect of polymer structure on blend miscibility with polyvinylphenol (PVPh) has been studied for at least one polymer from a variety of polymer classes with potential hydrogen‐bond accepting groups: polyesters (aliphatic and aromatic), polycarbonates, polyimides, polyamides, polysulfones, polyurethanes, polyethers, polysiloxanes, poly(amideimides), and cellulose esters. Many of the polyesters, polyamides, and cellulose esters showed evidence of interaction and miscibility with PVPh. In most of the other cases, there was no sign of miscibility. Generally good correlation exists between thermal behavior and infrared spectral data. Where there is significant interaction seen between the polymers by FTIR, substantial miscibility is seen by DSC analysis. In some cases, the phase behavior depended on the blend preparation scheme. © 1994 John Wiley & Sons, Inc.
Study of thermal and dyeing behavior of isotactic polypropylene fiber graft copolymerized with acrylate monomers using preirradiation method
Authors: Mehta I. K. , Misra B. N. , Chauhan G. S. 
Published: April 2003

AbstractIn an attempt to modify isotactic polypropylene (IPP) fiber, grafting of acrylate monomers such as methyl acrylate (MA) and ethyl acrylate (EA) onto IPP has been carried out by preirradiation method in aqueous medium. Percentage of grafting has been determined as a function of various reaction parameters. Rate of grafting (Rg) and induction period (Ip) have been evaluated as a function of total initial monomer concentration. Methyl acrylate was found to be more reactive than ethyl acrylate toward grafting. Thermogravimetric analysis (TGA) indicates that the thermal stability of polypropylene fiber is significantly improved upon grafting. While polypropylene fiber could not be dyed by crystal violet, the grafted fiber was dyed with crystal violet, and the dye uptake has been quantitatively determined by spectrometric method. © 1994 John Wiley & Sons, Inc.
PTC effect of polymer blends filled with carbon black
Authors: Jia Wentao , Chen Xinfang 
Published: April 2003

AbstractLow‐density polyethylene/ethylene‐propylene‐diene terpolymer (LDPE/EPDM) blends and LDPE/ethylene‐ethyl acrylate (EEA) blends were chosen as objects of study. Their positive temperature coefficient (PTC) phenomena and their distinctive aspects were described. The explanations were given from the structural characteristics of the blends. © 1994 John Wiley & Sons, Inc.
Polymeric phosphonium salts as a novel class of cationic biocides. X. Antibacterial activity of filters incorporating phosphonium biocides
Authors: Kanazawa Akihiko , Ikeda Tomiki , Endo Takeshi 
Published: April 2003

AbstractPhosphonium salts with different alkyl chains as substituents were incorporated covalently on the surfaces of cellulose filters with silane coupling agents containing phosphonium ions, and their surface antibacterial activities against Staphylococcus aureus and Escherichia coli were explored by the viable cell‐counting method in sterile distilled water. The filters incorporating phosphonium biocides showed higher antibacterial activity, and its activity strongly depended on the structure of substituents. The surface‐treated filters may be used to sterilize air and water, including microorganisms. © 1994 John Wiley & Sons, Inc.
Dynamic mechanical properties of polyurethane–urea microcapsules on coated paper
Authors: Ichikawa Kimio 
Published: April 2003

AbstractPolyurethane–urea microcapsules were prepared by an interfacial polymerization method. Dynamic mechanical measurements were carried out on the polyurethane–urea microcapsules coated on a paper substrate. The glass transition temperatures (Tg) of capsule wall were observed in the temperature scan data. Tg as the temperatures of tan δ peaks were decreased with increasing amounts of core materials. The apparent activation energies of the glass transition were estimated at about 100 kcal/mol. Master curves were obtained by shifting the tan δ spectra along the frequency axis, and the glass transition regions were unaffected by core materials studied. The shift factors were found to depend on the core/wall ratio and discussed in terms of a morphological change of microcapsules. © 1994 John Wiley & Sons, Inc.
Effect of polycyclopentene on crystallization of isotactic polypropylene
Authors: Lee Dong‐Ho , Yoon Keun‐Byoung 
Published: April 2003

AbstractThe application of some polymers as nucleating agents for polypropylene has been examined. Among various polymeric nucleating agents, polycyclopentene was found to be a superior nucleating agent to typical organic nucleating agents. When polycyclopentene was added to polypropylene, the crystallization temperature and the degree of crystallinity of polypropylene increased. In addition, the crystallization rate and the number of spherulites increased whereas the size of spherulites decreased remarkably. As a result of polycyclopentene addition, the transparency of polypropylene film could be improved considerably. © 1994 John Wiley & Sons, Inc.