bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the dynamic mechanical and vibration damping properties of polyether urethane and epoxy composites
Authors: Weibo Huang , Fengchang Zhan 
Published: April 2003

AbstractThe dynamic mechanical and vibration damping properties of polyether urethane and epoxy composites have been studied. The experiment results show: the crosslink density is an important factor that influences the loss factor of polyether urethane damping materials; increasing the amount of pendant methyl of the backbone contributes to raising the value of the loss factor (tan δ) and broadens the damping temperature range; adding the planar filler can increase the shear motion and the internal dissipation in polyurethane materials. As the thickness ratio and the Young's modulus of the constraining layer increase, the composite loss factor (η) increases significantly. © 1993 John Wiley & Sons, Inc.
Formation of entanglements at brushlike interfaces in cellulose–polymer composites
Authors: Felix Johan M. , Gatenholm Paul 
Published: April 2003

AbstractCellulose fibers were grafted with compatibilizing agents, such as maleated polypropylenes of different molecular weights. Steric effects and surface free‐energy effects were found to stimulate the stretching of grafted chains away from the cellulose fiber surface, giving rise to a brushlike configuration in a polypropylene (PP) melt. Inverse gas chromatography measurements on modified fibers using a model compound for PP as adsorbate showed that interactions of PP and grafted fibers, which were mainly diffusion‐dependent, increased with increasing molecular weight of the compatibilizer. Dynamic mechanical measurements and tensile testing of composites showed that the presence of compatibilizing agents enhanced stress transfer and increased interphase thickness considerably, the most significant effect being obtained for the high molecular weight compatibilizers. Apparently, the longer the grafted chains, the larger the fraction of matrix molecules involved in the interactions and, thus, the thicker the interphase. The improvement of adhesion between treated fibers and PP, as detected by peel testing, was proven to be caused mainly by entanglements formed between compatibilizing agents and PP. © 1993 John Wiley & Sons, Inc.
Molecular redesign of expanded polystyrene to allow use of carbon dioxide as a foaming agent. I. Reversible binding of CO2
Authors: Diaf A. , Enick R. M. , Beckman E. J. 
Published: April 2003

AbstractEnvironmental concerns, associated with the production of expanded plastics using hydrocarbon blowing agents, have spurred interest in environmentally‐friendly technology by which cellular materials, particularly expanded polystyrene, can be produced. Consequently, we have explored the possibility of using styrene‐based, amino‐functional copolymers to generate expandable systems, which would rely solely on CO2 as a blowing agent. Carbon dioxide is an attractive foaming agent in that it can be readily extracted from the air, is nonflammable, and exhibits low toxicity. Using a styrenic copolymer, functionalized with ethylenediamine (EDA), the results of this study show that aminated polymers are capable of reversibly binding weakly acidic gases, CO2 in particular. While the reaction products (polymer‐bound zwitterions) are stable under ambient conditions, decarboxylation can be thermally induced cleanly and easily. Work underway in our laboratory shows that microporous, as well as nonporous EDA‐functional copolymers, are effective, thermally‐reversible sorbents for acid gases. Furthermore, preliminary results show that these materials may also find potential applications in facilitated transport membrane technology. © 1993 John Wiley & Sons, Inc.
Surface acid‐base characteristics of fiber materials by contact angle measurements
Authors: Youan Mao 
Published: April 2003

AbstractContact angle measurements were used to study the surface acid‐base characteristics of treated and untreated carbon fibers, and of treated and untreated silicon carbide fibers. It has been shown that, when untreated, the surfaces of these two fibers exhibits “amphoteric,” but the base character is dominant. After oxidization in a liquid phase, the surface acid character of the carbon fibers changes little, whereas the base character becomes much stronger. The treatment, with boiling‐concentrated HNO3 for three hours and the sintering treatment in air at 500°C for eight hours, has little effect on the surface acid‐base characteristics of the silicon carbide fibers. © 1993 John Wiley & Sons, Inc.
Porous membrane of polydimethylsiloxane by hydrosilylation cure: Characteristics of membranes having pores formed by hydrogen foams
Authors: Kobayashi Takaomi , Saitoh Hitoshi , Fujii Nobuyuki , Hoshino Yoshikazu , Takanashi Masanori 
Published: April 2003

AbstractPorous polydimethylsiloxane (PDMS) membranes were prepared by catalytic hydrosilyiation cure of a silicone compound containing a vinyl group and a SiH group in the presence of additives such as water, ethanol, ethylene glycol, and 2‐methoxyethanol. The pores were formed in the membrane as a result of hydrogen foams produced by the reaction between the SiH group and the OH group of the additive during the cure. The cure reaction, hydrogen generation, and properties of the porous membranes that resulted were examined as a function of the additive concentration in the compound at various cure temperatures. As application of the membrane, the ultrafiltration properties were determined. © 1993 John Wiley & Sons, Inc.
Crystallinity in the polypropylene/cellulose system. I. Nucleation and crystalline morphology
Authors: Quillin Daniel T. , Caulfield Daniel F. , Koutsky James A. 
Published: April 2003

AbstractThe amount of research on lignocellulosic/thermoplastic composites has increased dramatically. Little attention, however, has been directed towards the subject of crystallinity at the interface (interphase). Optical microscopy and differential scanning calorimetry were used in this work to study crystallinity in the cellulose/polypropylene system. The results verify that cellulose acts as a nucleating agent for polypropylene, producing a transcrystalline region around the fiber. Treatment of the fibers with alkyl ketene dimer (AKD), alkenyl succinic anhydride (ASA), or stearic acid, inactivates the surface features responsible for transcrystallinity. These treatments also affect the overall degree of crystallinity of the sample. Morphological features, resulting from a transcrystalline or nontranscrystalline interphase, may have a significant effect on mechanical properties. A possible mechanism for the appearance of transcrystallinity involving crystal structure matching is also proposed. © 1993 John Wiley & Sons, Inc.
Modification of epoxy surfaces with different polyvinylalcohol polymers
Authors: Chihani T. , Flodin P. , Hjertberg T. 
Published: April 2003

AbstractAn epoxy resin, consisting of diglycidylether of bisphenol A (DGEBA) and methyltetrahydrophtalic anhydride (MTHPA), was cured against peel‐plies coated with different poly(vinylalcohol‐co‐vinylacetate) (PVOH). The epoxy polymer surface was characterized with X‐ray photo electron spectroscopy (XPS), contact angle measurements, and scanning electron microscope (SEM). PVOH, which is a water soluble polymer, was detected at the cured epoxy polymer surface with XPS after washing with hot water. The PVOH polymer at the outermost surface has hydroxyl groups, which can react with both the adhesive and the epoxy resin. The modified epoxy composite surfaces were adhesively bonded with a polyurethane and an epoxy adhesive. Improved adhesion was obtained between modified epoxy composite surfaces and different adhesives. © 1993 John Wiley & Sons, Inc.
Effect of glow discharge treatment of poly(acrylic acid) preadsorbed onto poly(ethylene)
Authors: Terlingen Johannes G. A. , Hoffman Allan S. , Feijen Jan 
Published: April 2003

AbstractIn order to introduce carboxylic acid groups at the surface of poly(ethylene) (PE) films, an attempt was made to covalently link a preadsorbed layer of poly(acrylic acid) (PAAc) on a PE film by an argon or tetrafluoromethane (CF4) plasma treatment. Surface analysis was performed by XPS (X‐ray photoelectron spectroscopy) and water contact angle measurements. It was shown that by treatment of a PAAc layer preadsorbed on PE with an argon or a CF4 plasma, a small amount of carboxylic acid groups was introduced at the surface. A similar amount of these groups was obtained by plasma treatment of PE films without a preadsorbed PAAc layer. A comparison of the etching rates of PAAc and PE by either an argon or a CF4 plasma, showed that PAAc is etched much faster by both types of plasmas than PE. The preadsorbed PAAc layer on PE is etched off before it could be immobilized by either an argon or a CF4 plasma treatment. Additionally the effect of treating PE films for very short times with an argon or a CF4 plasma was studied. After an induction period of approximately 0.1 s, the oxidation during the argon plasma treatment and the fluorination during the CF4 plasma treatment were proportional to the logarithm of the treatment time for time periods up to 50 s. © 1993 John Wiley & Sons, Inc.
Effect of reinforcing carbon black filler on thermally induced crosslinking of polyacrylic acid‐epoxidized natural rubber blend
Authors: Mallick A. , Tripathy D. K. , De S. K. 
Published: April 2003

AbstractThat carbon black filler influences the thermally induced crosslinking between polyacrylic acid (PAA) and epoxidized natural rubber (ENR) is evident from Monsanto rheometric studies, dynamic mechanical analyses, and physical property measurements. Considerable shift in glass transition temperature, as well as broadening of the loss peak due to ENR, along with disappearance of the loss peak due to PAA, indicate that HAF carbon black, at 20 parts per 100 of total polymer, make the immiscible PAA/ENR blend behave as a compatible blend. © 1993 John Wiley & Sons, Inc.
Benzoyl‐peroxide‐initiated graft copolymerization of poly(ethylene terephthalate) fibers with acrylic acid
Authors: Sacak Mehmet , Oflaz Fazli 
Published: April 2003

AbstractThe grafting of acrylic acid onto poly(ethylene terephthalate) fibers subjected to a noswelling treatment using benzoyl peroxide was investigated. The temperature was found to increase the graft yield. The grafting yield increased up to a benzoyl peroxide concentration of 4.0 × 10−3 M and slightly decreased at higher initiator concentrations. The effects of solvents such as dimethylformamide, dimethylsulfoxide, pyridine, and some alcohols upon the grafting were examined by carrying out the graft copolymerization at various water/solvent ratios. Pyridine was found to inhibit the grafting totally. The properties of the grafted fibers such as density, diameter, dyeability, and moisture regain were also investigated. It was concluded due to the observations made in these properties that the grafting took place mainly in the subsurface regions of the fibers and there occurred a diffusion barrier after the grafting value of 8–9%. The overall activation energy for grafting was calculated to be 9.9 kcal/mol. © 1993 John Wiley & Sons, Inc.
Infrared spectroscopy studies of the effects of the catalyst on the ester cross‐linking of cellulose by poly(carboxylic acids)
Authors: Yang Charles Q. 
Published: April 2003

AbstractThe esterification of cellulose by a poly(carboxylic acid) proceeds in two steps: the formation of a 5‐membered cyclic anhydride intermediate by the dehydration of two carboxyls, and the reaction between cellulose and the anhydride intermediate to form an ester. Sodium hypophosphite is the most effective catalyst for the esterification. The effect of sodium hypophosphite on the esterification of cotton cellulose was studied by Fourier transform infrared spectroscopy (FTIR). It was found that sodium hypophosphite accelerates both the formation of the cyclic anhydride intermediate and the reaction between the anhydride intermediate and cellulose. The chief role of sodium hypophosphite is possibly the acceleration of the esterification of cellulose by the anhydride intermediate. © 1993 John Wiley & Sons, Inc.
Crystallization kinetics of high‐density polyethylene/linear low‐density polyethylene blend
Authors: Gupta A. K. , Rana S. K. , Deopura B. L. 
Published: April 2003

AbstractThis article presents crystallization kinetics studies on a cocrystallizing polymer highdensity polyethylene (HDPE)/linear lowd‐ensity polyethylene (LLDPE) blend. The nonisothermal crystallization exotherms obtained by differential scanning calorimetry (DSC) were analyzed to investigate the effect of cocrystallization on kinetics parameters, namely the Avrami exponent and activation energy. The regular change of Avrami exponent with blend composition from a value of about 3 corresponding to HDPE to a value of 2 corresponding to LLDPE is observed. A sheaf‐like crystalline growth with variation of nucleation depending on blend composition is concluded from these results of DSC exotherm analysis in conjunction with the small‐angle light scattering observations. The observed variation of activation energy of crystallization with blend composition suggests the role of interaction of side chains and comonomer units present in the LLDPE. © 1994 John Wiley & Sons, Inc.
Syntheses and cured films properties of UV‐autocurable BTDA‐based multiacrylate resins
Authors: Chiang Wen‐Yen , Lin Wen‐Tser 
Published: April 2003

AbstractA series of UV‐autocurable 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA) and benzophenone tetracarboxylic acid (BTAc)‐based multiacrylate resins containing pendant glycidyl methacrylate (GMA) or glycidyl acrylate (GA) and 2‐hydroxyethyl acrylate (HEA) or 2‐hydroxyethyl methacrylate (HEMA) were synthesized. The effects of the acrylic functional groups, the moles of GMA, and the molar ratio of HEMA/HEA on their properties were investigated. The prepared autocurable resins are cured rapidly when exposed to UV or sunlight radiation without addition of any photoinitiator or Photosensitizer and the acrylate‐type resin resulted in a lower thermal curing temperature and a fast curing rate. Increasing the moles of GMA or the molar ratio of HEMA/HEA on reaction leads to a higher cross‐linking density and resulted in film with a higher Young's modulus, breaking strength, and lower elongation. The methacrylate‐type resin cured to a very hard, but brittle film with a higher Young's modulus and lower elongation. However, the acrylate‐type resin cured to a hard tough film with a lower Young's modulus and higher elongation. The cured methacrylate‐type resin results in a lower weight loss at temperature below 300°C due to a higher cross‐linking density and lower residual weight percent at 600°C due to the lower percent of benzene rings in the resin. The film properties of the resins coated on steel plates were also investigated. © 1994 John Wiley & Sons, Inc.
DNA‐like and phospholipid‐like phosphorylated polystyrenes: Characterization, distribution of functional groups, and calcium complexation properties
Authors: Imbert E. , Souirti A. , Menard V. , Pfluger F. , Jozefowicz M. , Migonney V. 
Published: April 2003

AbstractThe phosphorylation of cross‐linked polystyrene resins has been previously described. As seen by their interaction with lupus antibodies, these polymers were found to mimic either DNA or phospholipid antigens, depending on the degree of substitution by phosphate groups. When an alkyl spacer was included between phosphate groups and macromolecular chains, difficulties in synthesis and desorption of the biological species from the resins were seen. In this article, kinetic aspects of the synthesis of phosphorylated polymers, possessing sulfamide spacers, are discussed. The characterization of these phosphorylated polymers by acidimetric titration is extensively described. This technique differentiates and quantifies the grafted phosphate groups, which can be either phosphomonoester or phosphodiester in nature. We demonstrate that these polymers form complexes with calcium ions, and that the affinity of the ions is closely associated with the type of phosphate groups. © 1994 John Wiley & Sons, Inc.
Interfacial effects produced by crystallization of polypropylene with polypropylene‐g‐maleic anhydride compatibilitzers
Authors: Duvall J. , Sellitti C. , Myers C. , Hiltner A. , Baer E. 
Published: April 2003

AbstractTwo anydride‐grafted isotactic polypropylene (PP) compatibilizers, HAC or high‐anydride compatibilizer (2.7 wt % grafted maleic anhydride) and LAC or low‐anydride compatibilizer (0.2 wt % anydride), were compared in PP‐rich blends with polyamide‐66 (25 wt %). A previous article demonstrated that LAC imparted a much higher fracture strain than did HAC at similar anydride concentrations. The present study shows that LAC is capable of cocrystallization with PP. HAC does not cocrystallize, but crystallizes as a second phase in binary PP/HAC blends studied by DSC and hot‐stage microscopy. A cocrystallization model is proposed to explain the higher fracture strain of PP/LAC/PA blends. A. separate phase crystallization model is proposed for PP/HAC/PA blends. The models are supported by peel tests, which demonstrate greater adhesion of PP with LAC than with HAC. © 1994 John Wiley & Sons, Inc.
Acetals as nucleating agents for polypropylene
Authors: Smith Tammy L. , Masilamani Divakaran , Bui Long Kim , Brambilla Raymond , Khanna Yash P. , Garbriel Kristina A. 
Published: April 2003

AbstractNucleating agents increase the impact strength, tensile strength, and tensile elasticity modulus of semicrystalline polymers. Nucleating agents also decrease product cycle times, resulting in a cost savings per product unit. We have synthesized and tested 15 compounds as nucleactors for polypropylene. Of these, trinapthylidene sorbitol, tri‐(4‐methyl‐1‐naphthylidene)sorbitol, tri‐(4‐methoxy‐1‐naphthylidene) sorbitol, and dibenzylidene xylitol are efficient nucleators of polypropylene. Trinaphthylidene sorbitol (tns) has two major diastereomers: The “S” diastereomer yields a faster crystallization rate for polypropylene than does the commercial nucleator dibenzylidene sorbitol (Millad 3905). Crystallization rates are 208 and 88, respectively (t min−1 × 1000). The “R” diastereomer, however, is a poor nucleator and interferes with the nucleating activity of the “S” diastereomer. A 52/48 mixture of diastereomers does not nucleate polypropylene, even at twice the concentration. This is first time that the importance of stereochemistry has been demonstrated in the nucleating action. © 1994 John Wiley & Sons, Inc.
Behavior of amine‐modified urea–formaldehyde‐bonded wood joints at low formaldehyde/urea molar ratios
Authors: Ebewele Robert O. , River Bryan H. , Myers George E. 
Published: April 2003

AbstractUrea–formaldehyde‐bonded wood products are limited to interior nonstructural applications because of their poor durability under cyclic moisture or humid environments. The stability of solid‐wood joints and particleboards can be enhanced by bonding with urea–formaldehyde adhesives modified with di‐ and trifunctional amines at an effective resin formaldehyde‐to‐urea mol ratio (F/U) of 1.6; however, particleboard formaldehyde emissions were not improved over those from boards made with unmodified adhesives and were unacceptably high. The relative effectiveness of selected modifications was investigated at resin form aldehyde‐to‐urea (F/U) molar ratios of 1.4 and 1.2 Solid‐wood joints and particleboards made with modified adhesives, an unmodified adhesive, and a phenol formaldehyde (PF) resin were subjected to cyclic soak‐dry (cyclic stress) treatments and moist‐heat aging. Formaldehyde emissions from particleboards were also determined. At F/U 1.4, the resistance of solid‐wood joints made with modified adhesives to cyclic stress and moist‐heat aging was equal to that of PF‐bonded joints and superior to that of joints bonded with unmodified adhesive. The resistance of particleboards made with modified adhesives was greater than that of boards made with unmodified adhesive but less than that of PF‐bonded board. Solid‐wood joints and particleboards made with F/U 1.4 resins performed better than did those made with F/U 1.2 resins. Particleboards made with F/U 1.2 resins had formaldehyde emissions well below the standard, and room temperature aging or bonding at high temperature reduced emissions substantially. © 1994 John Wiley & Sons, Inc.1This article is a US Government work and, as such, is in the public domain in the United States of America.
Sulfonation of cross‐linked asymmetric membranes based on polystyrene and divinylbenzene
Authors: Byun H. S. , Burford R. P. , Fane A. G. 
Published: April 2003

AbstractAsymmetric microporous membranes based on polystyrene cross‐linked with divinyl benzene were prepared. They were sulfonated with sulfonic acid and washed with solutions of gradually increasing pH to reduce environmental shock. The sulfonation was monitored by infrared spectroscopy, and changes in wettability and sulfur content were also recorded. Morphologies and reverse osmosis performance of sulfonated membranes were measured, with both water flux and salt rejection increasing after treatment. © 1994 John Wiley & Sons, Inc.
Polypropylene/poly(vinyl acetate) blend fiber
Authors: Xiao Weiwei 
Published: April 2003

AbstractPolypropylene/poly(vinyl acetate) (PP/PVAc) (30/70) blend possesses higher thermal stability than PVAc and is stable below 300°C. The viscosity of the blend is lower than that of PP and PVAc at 220°C. The blend fibers have sheath‐core morphology; the core is composed of PP fibrils because PP has reasonably higher viscosity than PVAc. Due to the reinforcement of PP fibrils, the tensile strength and modulus of the blend fibers were increased. The blend fibers drawn at 50°C possess better mechanical properties than those drawn at 90°C. © 1994 John Wiley & Sons, Inc.
Pervaporation separation of binary organic–aqueous liquid mixtures using cross‐linked PVA membranes. II. Phenol–water mixtures
Authors: Rhim Ji‐Won , Sohn Min‐Young , Lee Kew‐Ho 
Published: April 2003

AbstractThe pervaporation separation of water‐phenol mixtures was carried out using poly(vinyl alcohol) (PVA) cross‐linked membranes with low molecular weight poly(acrylic acid) (PAA) at 30, 40, and 50°C. The separation was concentrated on the second stage of the water‐selective process at which the phenol concentration could be 80 wt % of phenol. The high separation factor of αw/p, = 3580 for the PVA/PAA = 80/20 membrane was obtained for the phenol : water = 80 : 20 solution at 30°C. © 1994 John Wiley & Sons, Inc.