bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vibration damping with urethane/acrylate simultaneous semi‐interpenetrating polymer networks
Authors: Tung Chein‐Jen , Hsu Tzu‐Chien J. 
Published: April 2003

AbstractThe vibration damping efficiency of the IPN‐laminated steel sheet, which consisted of a viscoelastic IPN layer sandwiched between two steel sheets, was investigated in this study. The simultaneous semi‐IPN used included an elastomeric urethane phase and a glassy acrylate phase. This study seeks to develop a laminate, with broader damping temperature and frequency ranges, in contrast to the homopolymer‐based laminates studied previously. A vibration damping analysis of the neat IPNs was first conducted using a dynamic rheometer in order to provide basic rheological properties of the neat IPNs. This was followed by the frequency spectrum analysis of the IPN‐based laminates, using a frequency analyzer, utilizing the results derived from the damping analysis of the neat IPNs. The IPN variables studied included the reaction temperature, the amount of the catalyst for urethane phase, the composition in acrylate phase and in urethane phase, and the composition of IPN. The results indicated that, by properly adjusting the IPN parameters, the extent of phase separation in IPN could be controlled. The effect of the network formation in the catalyzed urethane phase on the damping properties of IPNs was also investigated and the possible reaction mechanism was analyzed. The IPNs with catalyzed urethane phase showed single, smooth damping curves with peak values of tan δ = 0.4–0.7 in a broad temperature range. The study was then extended to the analysis of the vibration damping efficiency of the IPN‐based laminated, including the effect of IPN composition, the effect of the urethane composition in IPN, and the effect of the acrylate composition in IPN. The results indicated that the IPN‐based laminates yielded a maximum loss factor in the range of 0.1–0.5, which was below the tan δ value of IPN, but was better than that of the neat steel sheet. In addition, most of the damping properties of the laminates could be derived or predicted from the dynamic rheological properties of the neat IPNs. Thus, knowing the basic dynamic rheological properties of the neat IPNs is vital for a successful design and application of the IPN‐laminated steel sheet. © 1992 John Wiley & Sons, Inc.
Dynamic‐mechanical behavior of highly drawn isotactic polypropylene
Authors: De Candia F. , Romano G. , Baranov A. O. , Prut E. V. 
Published: April 2003

AbstractFibers of isotactic polypropylene were obtained by high‐temperature drawing, adopting a two‐stage process. Very high drawing degrees were achieved, more than 40. The physical behavior was analyzed by determining the dynamic‐mechanical relaxation spectra in monoaxial stretching. The results obtained show that the elastic modulus reaches a saturation value at deformation degrees of about 20, well below the drawability upper limit, indicating that above 20 any further drawing does not affect the structure. Moreover the α transition appears weak or absent in the drawn samples, while the β transition is still readily detectable. Both effects agree with Peterlin's model of drawing and with the fiber structure. © 1992 John Wiley & Sons, Inc.
Blends of polyamide 6 and bisphenol‐A polycarbonate. Effects of interchange reactions on morphology and mechanical properties
Authors: Gattiglia E. , Turturro A. , Lamantia F. P. , Valenza A. 
Published: April 2003

AbstractBlends of polyamide 6 (PA6) and polycarbonate (PC) were prepared in a Brabender mixer, at 240°C, applying long mixing time, for 45 min. It was observed that the morphology and the mechanical properties tend to resemble those of a homogeneous material as the mixing time and PA6 concentration increase. This is attributed to chemical reactions taking place between the two homopolymers. Acidolysis, amidolysis, and aminolysis, catalyzed by the terminals and the amide groups of the polyamide, should in principle be possible. Our results indicate that the aminolysis is the main process, inducing simultaneously scission of PC chains and formation of PC‐PA6 copolymer chains. The latter act as interfacial agents between incompatible PA6 and PC, improving the mechanical properties of PA6‐rich blends, in agreement with the predictions of some theoretical models assuming good phase interpenetration. © 1992 John Wiley & Sons, Inc.
Structure of heat‐treated nylon 6 fibers. I. Application of the arrhenius equation
Authors: De Godoy Oriani Luis Alberto , Simal Abigail Lisbão 
Published: April 2003

AbstractThe changes in lateral order, crystalline perfection index, crystallinity percentage, long period, and shrinkage denote the structural modification due to thermal effects in the heat‐treated nylon 6 fibers. The application of the Arrhenius equation to these parameters resulted in two types of behavior: the parameters long period and shrinkage showed linearity in the temperature range of 100–190°C, while the others presented linearity between 150 and 190°C. The first reflects the direct dependence of crystal growth on shrinkage and the latter shows that the necessary energy to promote significant crystal growth and perfection will be reached only at 150°C. In the range of temperature from 100 to 150°C the observed increase of crystallinity is associated to chain flexibility allowing rearrangement as well as new crystal formation. This phenomenon seems to be related to the discontinuity observed in the Arrhenius plots in the same range of temperature. © 1992 John Wiley & Sons, Inc.
Use of spherical tannin resin as a support for immobilized enzyme
Authors: Yamaguchi Haruhiko , Miura Kouji , Higuchi Mitsuo , Sakata Isao 
Published: April 2003

Abstractα‐Amylase (α‐1, 4‐glucan 4‐glucanohydrolase 3.2.1.1) was used to investigate whether the spherical tannin resins made by the reaction of Mimosa (Acacia Mollissima, Wattle) tannin (condensed‐type tannin) (MT) with formaldehyde could be used as a support for the immobilization of enzymes. It was found that the optimum pH range of the immobilized α‐amylase was wider than that of native α‐amylase, and the shelf life of the enzyme was increased by immobilization. Furthermore, the immobilized enzyme could be used repeatedly, and in a continuous enzyme reaction increased a further advantage of the technique. On the basis of these data, it was concluded that this resin could be used as a support for the immobilization of enzymes. © 1992 John Wiley & Sons, Inc.
Impact failure of poly(methyl methacrylate)
Authors: Bevan L. , Reed P. E. 
Published: April 2003

AbstractDamage development during instrumented falling weight impact (IFWIM) testing of poly(methyl methacrylate) (PMMA) is recorded using short pulse photography. The first visible damage is cracking on application of the peak force. Finite element analysis predicts the deformation and state of stress throughout the specimen until the first point of failure is reached. A variation in the specimen geometry produces a significant change in initial failure energy, while the maximum tensile stress is approximately constant. The proposed failure criterion is the attainment of a critical time‐dependent value of tensile stress. © 1992 John Wiley & Sons, Inc.
Synthesis and characterization of suspension‐polymerized poly(vinyl alcohol) beads with core–shell structure
Authors: Kim Cherng‐Ju , Lee Ping I. 
Published: April 2003

AbstractA new method of preparing large spherical PVA beads (up to 1.5 mm diameter) with a core‐shell structure has been developed. This involves a stepwise saponification of suspension polymerized PVAc beads, followed by a stepwise crosslinking of the PVA core and shell with glutaraldehyde. The resulting composite PVA beads have thin, highly crosslinked outer shells and lightly to moderately crosslinked inner cores of different degrees of crosslinking. In addition to the characterization of structural parameters, the kinetics of solute release and the swelling dynamics, including the transient dimensional changes, have been investigated using proxyphylline as a model compound. © 1992 John Wiley & Sons, Inc.
Adhesion enhancement of rubbery and ductile polyolefin coatings on glass fibers for epoxy composites and effects on failure mechanism
Authors: Mascia L. , Dhillon J. , Harper J. F. 
Published: April 2003

AbstractDilute polyolefin solutions, respectively based on EPDM and UHMWPE, were reacted with functionalized silanes to prepare coatings for glass fibers. These were found to provide adequate bonding characteristics for both glass and epoxy resin (bisphenol type). Unidirectional composites containing fiber matrix interlayers, using fibers coated with the aforementioned functionalized polyolefins, were found to exhibit much larger tanδ values over the temperature range of 60 to +60°C and greater ductility in flexural tests, albeit at the expense of a reduction in failure stresses. The UHMWPE coatings produced a multiple step fracture mechanism, which was deemed to provide a more efficient crack stopping mechanism than equivalent EPDM coated fibers. © 1993 John Wiley & Sons, Inc.
Studies on the grafting of methyl methacrylate onto polyacrylonitrile
Authors: Asaduzzaman A. K. M. , Raval Heta , Devi Surekha 
Published: April 2003

AbstractGrafting of methyl methacrylate onto polyacrylonitrile was carried out using benzoyl peroxide as initiator and dimethylformamide as solvent. The occurrence of grafting was confirmed by IR spectroscopy and SEM analysis. Effects of various parameters such as reaction time, reaction temperature, initiator concentration, and monomer concentration on rate of polymerization, percentage grafting, and grafting efficiency were studied. The graft copolymers were found to have the similar thermal and structural properties like virgin polyacrylonitrile. Decreasing extent of swelling was observed for the polymers of higher percentage graft in polar solvents. © 1993 John Wiley & Sons, Inc.
Thermal behaviour and adhesive properties of some cyanoacrylate adhesives with increased heat resistance
Authors: Denchev Z. Z. , Kabaivanov V. S. 
Published: April 2003

AbstractCured adhesive layers produced from ethyl‐(ECA), allyl‐(ACA), and allyloxyethyl‐(AOECA) 2‐cyanoacrylates were studied by means of thermogravimetry and differential scanning calorimetry. Polymer films of ECA‐based adhesive compositions comprising various amounts and types of 2‐cyano‐2,4‐pentadienoic acid (CPDA) esters were also examined. The influence of the modifier type, as well as the chemical structure of the cyanoacrylates used, was followed upon the glass transition temperatures (Tg) and the rates of thermal degradation of the corresponding polymers. In the case of cured adhesive mixtures containing unsaturated CPDA esters and when poly(ACA) and poly(AOECA) were studied, a significant increase of their heat resistance was established, as compared with poly(ECA). This fact was explained with the formation of three‐dimensional structure of the polymer film due to crosslinking reactions. A different course and character of these reactions were found comparing the thermal behavior of poly(ACA) and cured compositions containing unsaturated CPDA esters. A good agreement was found between data from the thermal analyses and the tensile shear and impact strength tests. It was shown that the modification of ECA with unsaturated CPDA esters is a possible way of increasing the heat resistance of the basic adhesive. © 1993 John Wiley & Sons, Inc.
Photodegradation of oxidized cotton cellulose
Authors: Buschle‐Diller Gisela , Zeronian S. Haig 
Published: April 2003

AbstractDifferent functional groups were systematically introduced into cotton cellulose and their effect on the stability of cotton toward photochemical degradation was examined. First, the cotton was progressively oxidized with sodium metaperiodate up to an oxygen consumption of 2.45 atom per 100 anhydroglucose units (agu) to form 2,3‐dialdehyde cellulose. These products were reduced with potassium borohydride to obtain 2,3‐dialcohol cellulose or were oxidized with sodium chlorite to obtain 2,3‐dicarboxyl cellulose. The chemical modifications of the cellulose structure caused a drop in tensile strength of 34% for the dialdehyde of 2.45 oxygen consumption per 100 agu compared to 27% and 37% in the case of the dialcohol and the dicarboxyl celluloses, respectively. Upon irradiation with UV light, the breaking strengths of the dialcohol and the dicarboxyl celluloses were generally higher up to an oxygen consumption of 0.63 per 100 agu when compared to the dialdehyde and then fell more drastically. The tensile data of the exposed oxycelluloses correlated well with the reciprocal of their intrinsic viscosities (R2 = 0.89). The primary alcohol groups appeared to accelerate the progress of the photochemical degradation. The photochemical effects of the carboxyl groups could not be differentiated from the autohydrolysis to which dicarboxyl cellulose is susceptible. No indication of a change in morphology was detected for any of the treatment types. © 1993 John Wiley & Sons, Inc.
Cure of epoxy novolacs with aromatic diamines. I. Vitrification, gelation, and reaction kinetics
Authors: Oyanguren P. A. , Williams R. J. J. 
Published: April 2003

AbstractThe cure reaction of a commercial epoxidized novolac with 4,4' diaminodiphenylsulfone (DDS) was studied at constant cure temperatures in the range 120–270°C, as well as at constant heating rates (differential scanning calorimetry, DSC). Stoichiometric formulations did not attain complete conversion due to the presence of topological restrictions. The limiting conversion was xmax = 0.8. Samples containing an amine excess (≥ 20%) could be completely reacted, whereas this was not possible for formulations containing an epoxy excess. Samples containing a 20% amine excess showed the maximum value of the glass transition temperature (Tg230°C). Cure took place by epoxy‐amine hydrogen reactions catalyzed by (OH) groups. A reactivity ratio of secondary to primary amine hydrogens equal to 0.2 was found. The activation energy was E = 61 kJ/mol, as arising from Tg versus time shift factors and time to gel measurements. A unique relationship between Tg and x could be obtained. Gelation took place at xgel = 0.45 and the maximum Tg for the stoichiometric system was Tgmax = 215°C for x = 0.8. A conversion versus temperature transformation diagram was used to represent conditions where gelation, vitrification, degradation, and topological limitations took place. © 1993 John Wiley & Sons, Inc.
Tensile properties of short sisal fiber‐reinforced polyethylene composites
Authors: Joseph Kuruvilla , Thomas Sabu , Pavithran C. , Brahmakumar M. 
Published: April 2003

AbstractSisal fibers (Agave‐Veracruz) have been used as reinforcements in low‐density polyethylene (LDPE). The influence of the processing method and the effect of fiber content, fiber length, and orientation on tensile properties of the composites have been evaluated. The fiber damage that normally occurs during blending of fiber and polyethylene by the meltmixing method is avoided by adopting a solution‐mixing procedure. The tensile properties of the composites thus prepared show a gradual increase with fiber content. The properties also increased with fiber length, to a maximum at a fiber length of about 6 mm. Unidirectional alignment of the short fibers achieved by an extrusion process enhanced the tensile strength and modulus of the composites along the axis of fiber alignment by more than twofold compared to randomly oriented fiber composites. © 1993 John Wiley & Sons, Inc.
Identification of volatile compounds resulting from the thermal oxidation of polyethylene
Authors: Bravo A. , Hotchkiss J. H. 
Published: April 2003

AbstractThe migration of compounds from polymer‐based packaging may impart undesirable odors to foods. We, therefore, undertook a study of the volatile compounds produced during the heating of polyethylene (PE) in the presence of excess O2 at temperatures of 150–350°C and for heating times of 5–15 min. Eightyfour volatile compounds in the range of C5—C23 were identified by gas chromatography mass spectrometry. The major products were aliphatic hydrocarbons, aldehydes, ketones, and olefins. Changes in temperature and heating times affected the amount and type of compounds produced, with hexanal being found in the largest amount and 300°C resulting in the greatest quantity of volatile compounds. At 350°C, greater amounts and numbers of low‐boiling and fewer high‐boiling compounds were formed. Only small amounts of volatiles were produced at 150°C. Many of the compounds identified have been reported to have odor and/or toxicological significance. © 1993 John Wiley & Sons, Inc.
Emulsification and electrodeposition of mixtures of cationic resins. I. Cationic resin and nonionic cross‐linker
Authors: Yang Chin‐Ping , Chen Yahn‐Haur 
Published: April 2003

AbstractThe emulsification and electrodeposition properties of two resins system (cationic epoxyamine adduct,III, was the main resin; nonionic trimethylolpropane–toluene diisocyanate‐2‐ethylhexanol resin,II, was used as cross‐linker) were investigated and the compositions of their electrodeposited films were obtained by Fourier transform infrared (FTIR) quantitative analysis to study the coemulsion and electrophoretic behaviors. The optimum resin compositionof coemulsion was also found to provide the deposited film having the best properties. The results indicate that the molecules of nonionic cross‐linkerIIare entangled by the ones of cationic resinIIIduring the dispersion process and they can be codeposited on the cathodic substrate after a voltage has been applied. Moreover, at the condition of stable coemulsion of the two‐component system, the resin composition of electrodeposited film is almost equal to the resin composition of the coemulsion and is not affected by the applied voltage or resin concentration. © 1993 John Wiley & Sons, Inc.
A new method to predict the maximum packing fraction and the viscosity of solutions with a size distribution of suspended particles. II
Authors: Sudduth Richard D. 
Published: April 2003

AbstractA new analysis technique has been developed in this paper to evaluate the upper limit of the packing fraction, φn utilized in the prediction of suspension viscosities. The semiempirical equation developed for the upper limit of the packing fraction, φn was generated initially from McGeary's binary particle packing fraction data. All possible Dx/Dy ratios of particles size averages were evaluated and analyzed in this formulation development. Only the D5/D1 and D4/D2 ratios of particle diameter averages were found to accurately predict the proper particle volume fraction location obtained in McGeary's data for the correct upper limit packing fraction φn. After developing methodology to calculate φn for binary particle distributions, an extension was made to include distributions with any number n of different particle size diameters. One of the more general of the suspended particle viscosity equations, as developed in a previous paper by this author, was used to demonstrate the application of this new φn methodology to the evaluation of suspension viscosity properties. The blended binary suspension viscosity results of Johnson and Kelsey for near monodisperse latexes were shown to be satisfactorily predicted as a function of the binary volume composition. © 1993 John Wiley & Sons, Inc.
Characterizing keratins using high‐pressure differential scanning calorimetry (HPDSC)
Authors: Wortmann F.‐J. , Deutz H. 
Published: April 2003

AbstractApplying differential scanning calorimetry (DSC) for temperatures up to 180°C, the denaturation transition of the α‐helical material of various keratins in excess water was studied at conditions of equilibrium water vapor pressure (high‐pressure DSC). The results show a generally cystine content and material invariate denaturation range of 20–30°C with peak temperatures around 140°C. Though analysis of variance and multiple comparison tests show a pronounced inhomogeneity of the enthalpy data, the results generally support the material invariance of the denaturation enthalpy and hence of the helix content of the keratins. The denaturation enthalpy for the helical coiled‐coil‐structures in the intermediate filaments is determined as ΔH = 6.5–7.8 kJ/mol. A significant positive correlation was found between the denaturation temperatures and the cystine content. It is concluded, that the helix denaturation temperatures are kinetically controlled by the amount and/or the chemical composition of the surrounding nonhelical matrix, and that the double‐peak endotherms observed for wool and other keratins originate from two cell types that are sufficiently different in sulfur content to allow endotherm separation. In the case of wool the cell types can be identified as “ortho‐” and “paracortical” cells. © 1993 John Wiley & Sons, Inc.
Effect of a diazide as adhesive agent in elastomeric matrix–short polyamide fibers composite
Authors: Ibarra Luis , Jordá Carmina 
Published: April 2003

AbstractThe effect of a diazide, chemically bonded to short polyamide fibers, has been investigated in order to establish if the diazide acts effectively as a bond bridge between the elastomeric matrix and the fibers. Composite properties, such as green strength, solvent swelling, tensile and tear strength, and elongation at break, which clearly manifest the existence of a strong interface, have been measured in comparison with those obtained in a similar composite with a conventional adhesive system. Likewise, the temperature dependence of tan δ showed a dispersion peak in the temperature range 30–90°C, which corresponds to the addition of the two relaxations related to the fiber and the interface. © 1993 John Wiley & Sons, Inc.
The modification of nylon 6 by a phenol‐formaldehyde resin
Authors: Huang Misty W. , Zhu K. J. , Pearce Eli M. , Kwei T. K. 
Published: April 2003

AbstractModification of nylon 6 by blending with a small amount of a novolac resin has been investigated. Unexpected increased of Tg and tensile modulus and reduction in moisture absorption have been found at levels of novolac incorporation of 1–3 wt %. The small amount of novolac resin also has an effect on the crystallization and nylon 6 crystal structure (α vs. γ form). © 1993 John Wiley & Sons, Inc.
Synthesis and polymerization of lignin‐based macromonomers. III. Radical copolymerization of lignin‐based macromonomers with methyl methacrylate
Authors: Da Cunha C. , Deffieux A. , Fontanille M. 
Published: April 2003

AbstractThe radical copolymerization of methyl methacrylate (MMA) with lignin fragments (resulting from flash hydrolysis) functionalized by polymerizable groups is investigated. To transform lignin fragments into macromonomers, the anchoring of styrenyl and methacryloyl groups has been first studied; the optimal conditions for an etherification or an esterification of hydroxy functions in lignin residues, by chloromethylstyrene and methacryloyl chloride leading to lignin‐macromonomers of controlled size and functionality, have been investigated. The influence of experimental conditions on both the degree of substitution and the characteristics of functionalized lignin fragments is discussed; linear and cross‐linked lignin‐MMA copolymers have been prepared. The accurate control of the number of anchored polymerizable groups per lignin fragment is a determining step that establishes the dimensionality of the chains and therefore the processability of the prepared copolymers. “Linear” lignin‐MMA copolymers containing up to 40% in mass of lignin have been obtained and some structural aspects of the corresponding materials are examined. © 1993 John Wiley & Sons, Inc.