bluuebunny/crossref_metadata_2025_split huggingface dataset:
Formation of polymeric microspheres using electron beam radiation
Authors: Mcherron Dale C. , Wilkes Garth L. 
Published: April 2003

AbstractPolymeric particulates are currently being produced by a variety of different techniques. This new approach illustrates the formation of cross‐linked polymeric microspheres by incorporating trimethylolpropane propoxylate triacrylate (a radiation‐sensitive monomer) into a polyaphron system and exposing it to electron beam radiation. Polyaphrons are essentially a collection of droplets encapsulated in a very thin aqueous film dispersed in a aqueous matrix. This film gives extreme stability to the system, which allows for extremely high dispersed‐phase concentrations. The formation of polyaphrons requires the presence of a surfactant in both the dispersed (monomer) and continuous (aqueous) phases. The effects of monomer‐phase concentration, monomer‐ and acqueous‐phase surfactant concentration, aqueous‐phase surfactant type, and preparation temperature were studied to gain an understanding of the conditions that promote the formation of polymeric microspheres with a narrow size distribution. Polymeric microspheres ranging from 2 to 40 microns in diameter were formed with monomer concentrations as high as 67 vol % without any aphron bridging occurring or need for agitation to keep the monomer‐phase dispersed in the aqueous matrix. In addition, the ability to reduce the wettability of the microspheres is demonstrated through incorporation of a polymerizable fluorinated acrylate in the dispersed phase.
Effects of voids on the response of a rubber poker chip sample. III
Authors: Kakavas P. A. , Blatz P. J. 
Published: April 2003

AbstractThe effects of voids on the response of a rubber poker chip sample are examined. A theoretical estimation of the diametral contraction of the sample was performed, using the linear theory of stress analysis. Experimental measurements of the lateral contraction at the middle plane of the poker chip elastomer specimen have shown that the testing rubber is not incompressible. By comparing the experimental data with the theoretical predicted equation, the value of the Poisson's ratio veff was found to be 0.487, for a given aspect ratio a* of the sample. A theoretical equation for the volume dilatation of the poker chip rubber sample was developed. Using the given aspect ratio, the value of veff, and the experimental stress/strain curve of the sample, an estimation of the volume dilatation was formed. The effective Poisson's ratio was also found using the linear stress analysis, by comparing the developed mathematical equations for an incompressible rubber with voids with a compressible one.
Graft polymerization of some vinyl monomers onto alkali‐treated cellulose
Authors: Mansour O. Y. , Nagieb Z. A. , Basta A. H. 
Published: April 2003

AbstractTreatment of cellulose by different concentrations of alkali, namely, 5–30% NaOH, changed its fine structure and transferred cellulose I into cellulose II. The decreased crystallinity due to alkali treatment and the transformation of cellulose I into cellulose II lowered the reactivity of cellulose toward the grafting polymerization reactions. Compactness of the structure as a result of the treatment of cellulose with 5% sodium hydroxide concentration decreased the rate of the grafting reaction and the grafting yield. On the other hand, such treatment of cellulose with different concentrations of alkali increased the rate of ceric consumption, i.e., increased the rate of oxidation of cellulose. Thus, the termination reaction of the grafting polymerization process may occur as a result of such oxidation and because of the increase of the active sites onto cellulose, leading to a decrease of the grafting yields and rate of grafting polymerization reaction by using the free‐radical grafting process. The use of the ionic‐xanthate method of grafting polyvinyl‐ and polyallyl‐on alkali‐treated cellulose shows an increase of grafting efficiency and grafting yields. Maximum grafting efficiency and yields were achieved when cellulose was treated with sodium hydroxide concentration below 15%, and maximum crystallinity indices were obtained. Using 15–25% sodium hydroxide lowered the indices of crystallinity, and lower grafting yields and grafting efficiency were achieved. Thus, transformation of cellulose I into cellulose II decreased the reactivity of these treated celluloses toward graft polymerization reactions by the use of the ionic‐xanthate method. In our opinion, termination reactions may also occur and affect the results.
Mathematical analysis of transport properties of polymer films for food packaging. VII. Moisture transport through a polymer film with subsequent adsorption on and diffusion through food
Authors: Smith Jeffrey S. , Peppa Nikolaos A. 
Published: April 2003

AbstractA system of partial differential equations was developed to describe the transient, three‐step transport of moisture through packaged food products. The steps included (i) Fickian diffusion through the polymer package film; (ii) Langmuirian adsorption upon the food surface; and (iii) Fickian diffusion through the food material. A set of finite difference equations was derived to approximate the continuous model. These equations were solved for standard boundary conditions in each section of the food packages. The results can be used for the determination of the food package shelf life.
Generation of spherical and monodisperse particles of poly(styrene) and poly(methyl methacrylate) by atomization of monomers and dissolved polymer precursors
Authors: Panagiotou Thomai , Levendis Yiannis A. 
Published: April 2003

AbstractA technique to produce spherical and monodisperse particles of selected polymers is presented. Liquid precursors of either mixtures of organic monomers and initiator catalysts or polymers dissolved in organic solvents were sprayed inside a vertical thermal reactor. The temperature range in the reactor was 400–670 K and the experiments were conducted in a nitrogen atmosphere. Atomization was achieved by an acoustically excited aerosol generator. Batches of equal size particles of two thermoplastic materials, poly(styrene) and poly(methyl methacrylate), were obtained in the range of 30–60 μm in diameter. Elemental analysis showed that the C and H composition of the produced particles was very close to theoretically expected values. The thermal environment, atomization conditions, and residence times the particles experienced in the reactor were explored using numerical techniques; residence times in the order of 4–10 s were estimated.
Surface properties of commercial polymer films following various gas plasma treatments
Authors: Wade William L. , Mammone Robert J. , Binder Michael 
Published: April 2003

AbstractSurface properties of a number of commercial thermoplastic polymer films were investigated before and after brief exposures to RF induced, low temperature gas plasmas. Water wettability and adhesion of vapor deposited aluminum to thin films (8–12 micron) of polyethylene, polypropylene, polyester, polysulfone, polycarbonate, and polyvinylidene fluoride films were studied before and after treatments with oxygen, 96% CF4/4% O2, and helium plasmas. Treatment with oxygen plasmas showed the greatest change in water wettability for polyvinylidene fluoride and polypropylene films, while treatment with 96% CF4/4% O2 showed dramatic changes in wettability of polycarbonate, polysulfone, and polystyrene. Excellent adhesion of aluminium was found for polymers that had been previously exposed to gas plasmas.
Infrared spectroscopic studies of the nonformaldehyde durable press finishing of cotton fabrics by use of polycarboxylic acids
Authors: Yang Charles Q. , Andrews B. A. Kottes 
Published: April 2003

AbstractA number of polycarboxylic acids have been used successfully as new nonformaldehyde cross‐linking agents for cotton fabrics. In our previous research, Fourier transform infrared photoacoustic spectroscopy (FTIR/PAS) demonstrated the ability for characterizing ester cross‐linkages in the finished cotton fabrics. In this research, the effects of different acid concentrations, different catalyst concentrations, different curing temperatures, and different curing times on the ester cross‐linking of the cotton fabrics were determined by FTIR/PAS. The infrared spectroscopic data were also correlated to durable press (DP) ratings. FTIR appears to be useful for evaluating the effectiveness of polycarboxylic acids as cross‐linking agents for cotton fabrics. FTIR definitely complements the existing methods for evaluating finished textile fabrics.
Preparation and characterization of low‐halogen and nonhalgoen fire‐resistant low‐smoke (FRLS) cable sheathing compound from blends of functionalized polyolefins and PVC
Authors: Sen Achintya Kumar , Mukherjee Bibha , Bhattacharya A. S. , Sanghi L. K. , De P. P. , Bhowmick Anil K. 
Published: April 2003

AbstractAn attempt is made to develop a novel series of cable sheathing compounds with variation in chlorine content and sufficient fire retardance and unique low‐smoke characteristics. These are prepared by blending PVC and functionalized polyolefins in different compositions. PE and EPDM have been functionalized by grafting dibutyl maleate (DBM) using DCP as initiator. FRLS compounds made from PVC‐functionalized polyolefin blends possess the special characteristics of low‐smoke, low‐acid‐gas generation, increased fire retardance, and improved volume resistivity, which are much better in comparison with a typical PVC sheathing compound. Thermoplastic elastomer (TPE) based nonhalogen FRLS compounds are also reported. The mechanisms for grafting, polymer‐polymer and polymer‐filler interactions have been presented.
Thermal degradation of EVA and EBA—A comparison. I. Volatile decomposition products
Authors: Sultan Bernt‐Åke , Sörvik Erling 
Published: April 2003

AbstractThis is the first in a series of papers in which structural changes during thermal degradation of ethylene‐vinyl acetate (EVA) and ethylene‐butyl acrylate (EBA) copolymers are compared. EVA, containing 11.4 mol% vinyl acetate (VA) and EBA, containing 5.4 mol% butyl acrylate (BA), were pyrolyzed at 280°C in nitrogen for 30 min. In another series of pyrolysis, EVA containing 1.2, 2.2, and 11.4 mol% VA were treated at 150–190°C for 3 h. The volatile decomposition products were collected in cooled traps respectively gas bags and then analysed with GC‐MS and ion‐chromatography. EVA is rather labile. The main volatile decomposition product is acetic acid. A linear decomposition rate was found already at the lowest investigated pyrolysis temperature, 150°C. After 30 min at 280°C every 15th of the acetate side groups had been eliminated. EBA is much more stable to pyrolysis. Thirty minutes at 280°C resulted in a decomposition of one out of 1500 BA groups. Butene is the main volatile decomposition product. Ester pyrolysis is supposed to account for the degradation of both types of polymers. The big difference in reactivity is presumably due to conformational differences. The ester pyrolysis mechanism will result in random unsaturations in EVA and carboxylic groups in EBA. To a minor extent acetaldehyde is formed when EVA is degraded. According to the mechanisms suggested, carbonyl groups remain in the main chain. Contrary to what is reported for poly(butyl acrylate), no alcohol was formed when pyrolysing EBA. This indicates that adjacent acrylate groups are needed for alcohol formation. For both types of polymer, scissions of the main chain results in hydrocarbon fragments mainly. In addition, acrylate containing fragments are observed when EBA is degraded. EVA, however, does not give any acetate‐containing fragments.
Thermal degradation of EVA and EBA—A comparison. II. Changes in unsaturation and side group structure
Authors: Sultan Bernt‐Åke , Sörvik Erling 
Published: April 2003

AbstractThis is the second in a series of papers in which the thermal degradation of ethylene‐vinyl acetate (EVA) and ethylene‐butyl acrylate (EBA) copolymers are compared. The EBA samples contain 0.8, 1.6, and 5.4 mol % butyl acrylate (BA), respectively, and the EVA samples 1.2 and 6.7 mol % vinyl acetate (VA). The samples were heated in nitrogen in a tubular oven at 285, 333, 350, 370 and 390°C for 6–120 min. The samples were analyzed with IR, NMR, gravimetry, and titration of carboxylic groups. The EVA samples were rapidly degraded by deacetylation, which was complete after about 30 min at 333°C. A linear relation between the loss of acetate groups and the formation of trans double bonds was found. A small amount of keto groups and traces of lactones were also observed. The data confirm the previously proposed mechanisms for deacetylation and the formation of acetaldehyde. A mechanism for lactone formation is suggested. The deacetylation rate is increasing with the VA content, presumably because of an increased amount of block sequences and an enhanced acid catalytic effect. The acrylate sidegroups are much more stable than the acetate groups, and are similar in stability to the main hydrocarbon chain. The BA decomposition results in carboxylic and anhydride groups. Decarboxylation also occur and increases with the thermal treatment. In LDPE and EBA the increase in unsaturation is small and mainly due to vinyl end groups formed via β‐cleavage or disproportionation. In EVA the formation of vinyl end groups is suppressed.
Thermal degradation of EVA and EBA—A comparison. III. Molecular weight changes
Authors: Sultan Bernt‐Åke , Sörvik Erling 
Published: April 2003

AbstractThis is the third in a series of papers in which the thermal degradation of ethylene‐vinyl acetate (EVA) and ethylene‐butyl acrylate (EBA) copolymers are compared. The EBA samples contained 0.8, 1.6, and 5.4 mol % butyl acrylate (BA), respectively, and the EVA samples 1.2 and 6.7 mol % vinyl acetate (VA). The samples were heated in nitrogen in a tubular oven at 285–390°C, for 6–120 min. The molecular weight distribution (MWD), long chain branching, and gel content were analyzed with size exclusion chromatography (SEC). The columns were connected to refractive index, viscometric, and light scattering detectors. EVA gave a pronounced molecular enlargement at all degradation temperatures. In EVA‐6.7, gel was formed at all degradation levels, whereas the low content sample, EVA‐1.2, did not form any visible amount of gel. The strong tendency to molecular enlargement is due to allyl radicals formed after thermal deacetylation and the formation of internal double bonds. These macroradicals will combine or, less frequently, add to double bonds. The EBA copolymers show a more polyethylenelike degradation behavior. At 285°C molecular enlargement dominates, but already at 333°C a net reduction in molecular size is observed. At high temperatures, ester pyrolysis of the BA groups give carboxylic groups and anhydrides. Alkaline treatment will not give any appreciable change in MWD, showing that the anhydride formation is mainly intramolecular. The chain scission increases with the BA content. This is probably due to β‐cleavage of tertiary macroradicals formed in the chain at the acrylate or carboxylic side groups.
Grafting of glycidyl methacrylate onto gelatin
Authors: Sivakumar M. , Radhakrishnan P. Rajalingam Ganga , Kothandaraman H. 
Published: April 2003

AbstractGelatin was graft copolymerized with poly(glycidyl methacrylate) using potassium peroxydisulfate in aqueous medium. Effect of temperature, time, initiator, monomer, and backbone concentrations were studied. The percent grafting was found to increase initially and then decrease in all the cases except with variation of monomer concentration. The rate of grafting, grafting efficiency, and percent of grafting were calculated. The grafting results have been discussed in the light of the rate of grafting. Mechanical properties, FT IR spectra, percent swelling, and percent dye uptake were carried out on the graft copolymerization and the results discussed.
Sizes of long‐chain branches in a high‐pressure low‐density polyethylene as a function of molecular weight
Authors: Usami Takao , Gotoh Yukitaka , Takayama Sigeru 
Published: April 2003

AbstractThe mean length and the indices of long‐chain branches (LCBs) of a high‐pressure lowdensity polyethylene (HPLDPE) as a function of molecular weight have been determined for its molecular‐weight‐tractionated parts by the 13C‐NMR analysis and the viscosity measurements. The mean LCB length of the fractions was of the order of 200–300 carbons in length. The size of LCBs increases with increasing molecular weight, but the size of LCBs relative to the overall macromolecular size decreases with increasing molecular weight. The LCB sizes as a function of molecular weight determined for the fractions of one parent HPLDPE are in good agreement with those previously reported for HPLDPE whole polymers.
Mechanism of the reaction involving the formation of dioxane byproduct during the production of poly(ethylene terephthalate)
Authors: Popoola A. V. 
Published: April 2003

AbstractThe formation of certain low molecular weight by‐products during the esterification reaction between ethylene glycol and dimethyl terephthalate was investigated. The result obtained showed that the presence of incorporated diethylene glycol within the polymer led to the formation of low molecular weight side products. An alcoholysis reaction involving the ethylene glycol and the ester was found to show a mechanism that is analogous to that of an ester interchange resulting in the production of the acid and the diethylene glycol precursor of the dioxane by‐product.
Melt rheological behavior of PP–SAN blend
Authors: Maiti S. N. , Agarwal Vanita , Gupta A. K. 
Published: April 2003

AbstractA study of melt rheology of the blend of styrene‐acrylonitrile (SAN) and polypropylene (PP) in composition range 0–50 wt % SAN content is presented. Measurements are made on a capillary rheometer at temperatures of 210, 230, and 250°C. The data are presented as flow curves and variations of melt viscosity and melt elasticity as functions of shear rate and blend composition. Scanning electron micrographs are presented to illustrate the dispersion and other characteristics of the SAN droplets. Results of melt rheology are interpreted in terms of the role of SAN droplets in the blend.
Short kevlar fiber–thermoplastic polyurethane composite
Authors: Kutty Sunil K. N. , Nando Golok B. 
Published: April 2003

AbstractMechanical and dynamic mechanical behavior of short Kevlar fiber‐filled thermoplastic polyurethane (TPU) have been studied with respect to fiber loading and orientation. The strength of the composite is improved at higher fiber content with a minimum at 10 phr of fibers. Storage and loss moduli (E′, E″) are increased and tan δmax is reduced progressively with fiber loading, the effect on moduli being more pronounced at post‐Tg temperatures. Anisotropy in strength is evident beyond 15 phr fiber loading. Impact strength is reduced considerably at all fiber loading irrespective of fiber orientation. Study of the fracture furface by scanning electron microscopy (SEM) shows good correlation between the modes of failure and strength of the composites. SEM study of the extracted fibers shows the existence of a kinking stage through which the fiber undergoes severe breakage during processing.
Copolymerization of styrene with vinyl monomers substituted by nitrile and sulfonyl groups
Authors: Knani Dafna , Kohn David H. 
Published: April 2003

AbstractTwo trisubstituted vinyl monomers, 2‐phenylsulfonyl (crotonitrile) and 2‐phenylsulfonyl (cinnamonitrile) were synthesized and characterized by proton NMR, IR, 13C‐NMR, and mass spectroscopy. Both monomers were copolymerized with styrene by free‐radical initiation. The copolymerization parameters of both systems were determined, and the mutual reactivity of the monomers of the two systems is discussed. The new copolymers were characterized by proton NMR and IR spectroscopy, melting range, Tg, and intrinsic viscosity. The influence of the chemical structures of the two comonomers on these two latter properties of the copolymers is discussed.
Copolymerization of turkish tall oil specimens with indene–coumarone. II. Production and properties of indene–coumarone modified tall oil varnishes
Authors: Üstün Güldem , Cívelekoǧlu Halídun 
Published: April 2003

AbstractTwo varieties of tall oil were copolymerized with indene–coumarone and subsequently esterified with ethylene glycol, glycerol, and pentaerythritol in addition to these esters, Urethanes were also obtained by reacting pentaerythritol esters of copolymers with toluene diisocyanate (TDI). These resultant products were evaluated as varnish vehicles and their film properties were compared with some standard formulation of tall‐oil‐ and vegetable‐oil‐based varnishes. The effect of indene–coumarone content of copolymer on the film properties of final products were additionally studied. Film evaluation showed that these copolymer‐based varnish vehicles could be used in the field of organic surface coating.
Size‐exclusion chromatography of high molecular weight water‐soluble polymers
Authors: Safieddine Abbas M. , Hester Roger D. 
Published: April 2003

AbstractA preparative‐scale, aqueous size‐exclusion chromatography system was constructed for fractionation of large molecular weight polymers. Calibration of molecular weight to elution volume was accomplished without polymer standards by using an eluent viscosity detector in series with a refractometer. The system was found to have a hydrodynamic size‐separation resolution that ranged from 500 to 3500 Å.
The application of the iosipescu shear test to structural adhesives
Authors: Grabovac I. , Morris C. E. M. 
Published: April 2003

AbstractThe Iosipescu shear test method, adapted for adhesives, was used to evaluate shear stress–strain properties of five epoxy‐based film adhesives. The shear strength of some adhesives, determined by this technique, was found to differ greatly from that determined by either lap shear and/or thick adherend tests. Accurate measurements of the adhesive bond‐line deformation enabled evaluation of the adhesive elastic and plastic properties as well as the calculation of shear modulus. A high‐speed video camera was employed to augment observation on the joint deformation.
FTIR characterization of tropical wood–polymer composites
Authors: Yap M. G. S. , Que Y. T. , Chia L. H. L. 
Published: April 2003

AbstractWood–polymer composites (WPC) of Geronggang (Cratoxylon arborescens), a light tropical hardwood, impregnated with methyl methacrylate (MMA), methyl methacrylate‐co‐acrylonitrile (1 : 1; MAN), and styrene‐co‐acrylonitrile (3 : 2; STAN), were prepared by in situ polymerization using gamma radiation or the catalyst–heat treatment. The FTIR spectra of the three types of WPC, with polymer loadings ranging from 10 to 70%, were compared with that of the wood itself and the respective polymers. Characteristic peaks due to CO vibration of MMA, CN stretching of acrylonitrile, and ring stretching and bending of styrene monomers, were prominent in the samples that had higher polymer loadings. For the copolymeric systems, quantitation of the FTIR spectra of these characteristic peaks enabled calculations of incorporated acrylonitrile and styrene monomers in the composites to be made. The FTIR spectra of the residues remaining, after exhaustive extraction to remove homopolymer, showed that graft copolymerization of wood components with acrylonitrile and styrene monomers was possible, but not with MMA. Composites prepared by the two methods, gamma radiation and the catalyst–heat treatment, were shown to be chemically very similar.