bluuebunny/crossref_metadata_2025 huggingface dataset:
Axial compressive strength of carbon fiber
Authors: Ohsawa Tadashi , Miwa Minoru , Kawade Masato , Tsushima Eiki
Published: April 2003

Efforts were made to estimate the axial compressive strengths of carbon fibers from the fiber fragment lengths produced by subjecting to a strain greater than the fiber ultimate strain for PAN‐based and pitch‐based carbon fibers. The estimated compressive strength of carbon fibers decreases with increasing temperature in a temperature range from room temperature to 100°C. This decrease in compressive strength may be accounted for by a decrease in the radial compressing force. The real compressive strength, determined by extrapolating a linear relationship between the estimated compressive strength and the radial compressing force, is approximately 25–60% of tensile strength for PAN‐based fibers, while it is approximately 10–35% for pitch‐based fibers.
Solid phase graft copolymerization. I. Effect of initiator and catalyst
Authors: Rengarajan Ramesh , Vicic Michael , Lee Sunggyu
Published: April 2003

Polypropylene–maleic anhydride (PP–MA) graft copolymers were produced from isotactic homopolymer polypropylene (molecular weight > 150,000) utilizing the technique of solid phase graft copolymerization. A high degree of graft (about 8–10%) was achieved on 150 mesh (U.S. Standard Sieve) samples using this process. This free‐radical‐initiated, catalyst‐aided grafting process was effective at low temperatures (100–120°C), atmospheric pressure, and low residence times (60 min). The powder was mixed in a low shear, fixed speed, continuous mixer where the ingredients were added in stages to effect the reaction. The interfacial agent was used to etch the polymer to provide sites for the reaction. The powder was removed from the reactor on completion of the reaction. This process can be further applied to graft other reactive monomers on polypropylene (PP).
Aspects of the surface and bulk nitration of cellulose in nitric acid, nitric acid/water, and nitric acid/dichloromethane mixes
Authors: Short R. D. , Munro H. S.
Published: April 2003

Electron spectroscopy for chemical analysis (ESCA) has been employed to follow the surface nitration of cellulose papers in nitric acid–water and nitric acid–dichloromethane mixes with the aim of: elucidating the identity of the nitrating species in these mixes and from comparison of surface and bulk degree of substitution (DOS) further understanding on the role that morphology plays in the nitration of cellulose in these mixes. In nitric acid, nitric acid–water and nitric acid–dichloromethane mixes, surface nitration was observed to be slow (cf. to that reported in mixed acids) and the concentration of nitronium ion was observed to be low (cf. to mixed acids). On the basis of these observations and from the results of kinetic experiments, reported herein, it is proposed that the nitronium ion, NO2+, is the important nitrating species of cellulose in these nitric acid mixes. Nitration in all but the most concentrated nitric acid–dichloromethane mixes produced equal surface and bulk DOS; however, nitration in pure nitric acid produced different surface and bulk DOS. The latter result implies that the heterogeneous nature of the nitration reaction can influence the DOS achieved.
Synthesis and characterization of mannich bases from cardbisphenol
Authors: Ramasri M. , Rao G. S. Srinivasa , Sampathkumaran P. S. , Shirsalkar M. M.
Published: April 2003

Water‐soluble Mannich bases were synthesized from cardbisphenol by Mannich reaction and were characterized by1H‐NMR and13C‐NMR spectroscopic methods. The effect of electrodeposition parameters on the film formation from binders and from the pigmented composition were studied. The polymers gave uniform coatings with good mechanical properties and the pigmented systems exhibited high resistance to organic solvents and excellent corrosion resistance properties.
Solute and penetrant diffusion in swellable polymers: X. Swelling of multiethylene glycol dimethacrylate copolymers
Authors: Walker Curt M. , Peppas Nikolaos A.
Published: April 2003

The swelling behavior of copolymers containing 2‐hydroxyethyl methacrylate and various multiethylene glycol dimethacrylates was examined at 25°C. These highly crosslinked copolymers show some hydrophilic behavior due to the hydroxyl groups of HEMA. Analysis of the swelling data indicates and anomalous water transport in the network, which depends on the degree of crosslinking attained according to the dimethacrylate comonomer molar fraction in the copolymerization feed. Thermomechanical analysis data were used to further characterize the network structure.
Deformation of polyelectrolyte gels under the influence of electric field
Authors: Shiga Tohru , Kurauchi Toshio
Published: April 2003

Deformation of acrylic acid–acrylamide copolymer gels in an aqueous solution under the influence of a dc electric field was studied. In the electric field, the gel swells, shrinks, or bends. It depends on the concentration of polyion coo− in the gel. When the concentration is low, the gel shrinks, and, when high, it swells. The gel which does not contain polyion is not influenced by the electric field. The long and thin gel is bent in an arc. The bent gel can be recovered to the original shape by removing the applied electric field or by changing the polarity of the applied electric field. The deformation is closely related to two substantial changes. One is the change of the osmotic pressure caused by the ion concentration difference between the inside and the outside of a gel. The other is the conformational change of the polymer network with decreasing of the polyion concentration.
Properties of epoxy resins cured with ring‐alkylated m‐phenylene diamine blends
Authors: Storey Robson F. , Dantiki Sudhakar , Adams J. Patrick
Published: April 2003

Diglycidyl ether of bisphenol‐A was cured, individually, with diaminoisopropyl benzene (DAIPB), diaminoethyl benzene (DAEB), blends of DAIPB/DAEB (up to 40 wt % DAEB), and DAIPB modified with up to 5 wt % amine‐terminated poly(butadiene‐co‐acrylonitrile) liquid rubber (ATBN). For each diamine system glass transition temperature (differential scanning calorimetry) and room temperature tensile properties (Instron) were determined. Blends of DAIPB/DAEB produced cured resins displaying greatly increased tensile strength (up to 50% higher) and slightly lower glass transition temperature compared with resins cured with either diamine alone. DAIPB modified with ATBN yielded moderately improved tensile properties over DAIPB alone. Blends of DAIPB/DAEB (from 10 to 40 wt % DAEB) were observed to be eutectic liquids at room temperature.
Studies on the physical properties of polyethylene‐g‐acrylic acid to immobilizing glucose oxidase
Authors: Hsiue Ging‐Ho , Wang Chee‐Chan
Published: April 2003

A new type of polymer support for immobilizing glucose oxidase was investigated. The starting copolymer was acrvlic‐acid‐grafted polyethylene (PE‐g‐AA). The copolymer was prepared with gamma ray irradiation induced grafting under controlled conditions utilizing post‐irradiation procedures. A number of factors were examined. They were: (1) the effect of the hydrophilic/hydrophobic nature of the support on the enzyme membrane activity; (2) the Michaelis constant (km); (3) the thermal stability, the rate constant for the thermal denaturation, and the activation energies for the denaturation of immobilized and soluble enzyme; and (4) the physical properties of the support affecting the immobilized enzyme activity. An attempt was made to immobilize the enzymeutilizing carbodiimide (CMC) as the coupling agent. This immobilization method resolves in a high enzyme activity. The hydrophilicity of the support and the activity of the enzyme membrane were proportional to the degree of grafting. When the temperature was higher than 60°C, the immobilized glucose oxidase was less sensitive to thermal inactivation than the native enzyme. Various polyethylene was studied; the LLDPE was preferred. The type of polyethylene, the thickness, kind of grafting monomers, and the degree of grafting would influence the activity of the enzyme membrane.
Measuring the modulus of a sphere by squeezing between parallel plates
Authors: Rodriguez Ferdinand , Patel Suman K. , Cohen Claude
Published: April 2003

Formulas are derived relating the deformation resulting from the application of a force f to the poles of a sphere of uniform modulus. When the force f is applied, the poles, originally a distance 2R* apart, now are a distance 2Ru apart. Also, the diameter of the sphere at its equator is increased from 2R* to a new value 2Re. For an ideal rubbery material with a shear modulus of g, the force is related to the change in equatorial diameter by

Thus, measurement of the increase in relative radius at the equator as a function of force applied at the poles yields the modulus directly. The change in Rv also can be related to G, but a numerical integration is required. Equations can also be derived relating modulus to dimensional changes when Hooke's law is used in place of ideal rubber elasticity.
Glow discharge polymerization of reactive functional silanes on poly(methyl methacrylate)
Authors: Laoharojanaphand P. , Lin T. J. , Stoffer J. O.
Published: April 2003

Glow discharge polymerization among such reactive functional silances as 3‐methacryloxypropyltrimethoxysilane (MSL), 3‐glycidoxypropyltrimethoxysilane (ESL), and vinyltrimethoxysilane (VSL) on poly(methyl methacrylate) was investigated by means of Fourier transform infrared spectroscopy, ESCA analysis, and contact angle measurement. Flow rate of monomer influenced both polymer deposition rate and polymer elemental composition. Infrared spectra showed differences in chemical structure among the polymers prepared from the different silanes. All of the polymers obtained contained similar chemical groups such as CH3, CH2, SiOSi, and SiOC. Polymers deposited from MSL and ESL contained highly hydrophilic functional groups like COH, SiOH, and CO on the uppermost layer while that from VSL contained highly hydrophobic functional groups like CH3 groups. Chemical analysis by ESCA and contact angle measurement gave evidence for the similarity of the polymers prepared from MSL and ESL, in contrast with the differences of the polymers prepared from VSL.
Pervaporation separation of water/ethanol mixtures through polysaccharide membranes. IV. The relationships between the permselectivity of alginic acid membrane and its solid state structure
Authors: Mochizuki Akira , Amiya Shigetoshi , Sato Yoshio , Ogawara Hisashi , Yamashita Shuzo
Published: April 2003

Membranes composed of alginic acid, which is one of the anionic polysaccharides, were investigated as pervaporation membranes for the separation of water/alcohol mixtures. The selectivity of the alginic acid membrane increased markedly by more than 10,000 when the carboxyl group of alginic acid was neutralized by bases. The counter cation (Li+, Na+, K+, Rb+, and Cs+) influenced the permeation rate for the alginate membranes, which varied from 0.1 kg/m2h for the Li version to 1.0 kg/m2h for the Cs version, but the counterion had hardly any effect on the selectivity. The behavior could not be explained simply by the affinity of the alginate membranes toward water, but could be explained well by the conformation change and mobility of alginate molecules investigated by CP/MAS 13C‐NMR, water mobility within the alginate membrane, and crystallinity of the membrane.
Mechanism of flame‐retardant action of tris (2,3‐dichloropropyl) phosphate on epoxy resin
Authors: Jianzong Li , Shiyuan Chen , Xiaoming Xu
Published: April 2003

The use of tris (2,3‐dichloropropyl) phosphate (TCPP) as a flame retardant in epoxy resin cured by methltetraphydrophthalic anhydride was studied. Although TCPP is an organophosphorus flame retardant containing chlorine, the date obtained from LOI measurements showed that TCPP was not more effective compared to other flame retardants containing only phosphorus. In order to understand the mechanism of flame retardant action of TCPP on epoxy resin, the effect of TCPP on the thermal degradation of the resin was investigated using thermogravimetry, differential scanning calorimetry, infrared spectroscopy, and elemental analysis. TCPP was shown to act predominantly by condensed phase mechanism, to catalyze decomposition, and to enhance char formation. A mode of flame retardant action of TCPP on epoxy resin by phosphorus in condensed‐phase was proposed.
The dependence of kinetic density curves of suspension PVC powder on the content of defective particles
Authors: S̆evčík Stanislav , Mrázek Zdeněk
Published: April 2003

The method of kinetic density curves was used to investigate the sieve fractions of suspension PVC powder of the type Neralit S‐682 with various content of difficult to process particles (“fish eyes”). It was found that by increasing the contenet of fish eyes, the effective density curves are shifted to lower density values. This finding can be utilized in the charaterization and evaluation of sieve fraction of PVC.
Studies on impact modification of polystyrene (PS) by ethylene–propylene–diene (EPDM) rubber and its graft copolymers. I. PS/EPDM and PS/EPDM‐g‐styrene blends
Authors: Shaw S. , Singh R. P.
Published: April 2003

Ethylene–propylene–diene (EPDM) rubber is an excellent rubber for outdoor use. High impact polystyrene (PS) containing EPDM rubber may show improved weathering resistance. PS is incompatible with EPDM; hence bulk polymerization technique is adopted for the synthesis of graft products which show limited compatibility with PS. Two initiators were chosen at two different working temperatures to produce high grafting efficiency and grafting percentage. In the present system, it is shown that the graft copolymer and polystyrene compositions show higher improved impact strength behavior than that of the products based upon simple dispersion of EPDM in polystyrene.
Effect of catalyst on the molecular weight advancement of poly(ethylene ether carbonate) polyols
Authors: Harris Robert F.
Published: April 2003

Sodium stannate is a parferred catalyst for the preparation of poly(ethylene ether carbonate) polyols. It can be removed from the polyol by treatment with acetone to precipitate most of the catalyst followed by adsorption of the soluble catalyst on Florisil and filtration. Sodium metaborate and potassium carbonate catalysts are not precipitated to any extent by acetone but can be reduced to lower levels by adsorption on Florisil and filtaration. The molecular weight of the poly(ethylene ether carbonate) polyol and the water content of the system have a strong influence on the effectiveness of this purification technique. Catalysts are more easily removed from higher molecular weight polyols with low water content. The effect of sodium stannate catalysts level on the molecular weight advancement of poly(ethylene ether carbonate) polyols has been studied. The rate of advancement to a 3000 molecular weight product is increased with good CO2 retention (95%) when the tin level is 100–500 ppm. At higher catalyst levels, product decomposition to 1,4‐dioxane becomes increasingly important. Complete mass balances and distillate analyses are presented to show the effects of catalyst levels. The product composition is dominated by the CO2 content of the reactant and the advancement conditions.
Polymeric reaction of polymer–monomer system irradiated by low‐energy electron beam. IV. Adhesive properties of pressure sensitive adhesive
Authors: Takiguchi Ryohei , Uryu Toshiyuki
Published: April 2003

Electron beam (EB) preparation and properties of pressure sensitive adhesives were investigated. The pressure‐sensitive adhesive was obtained by EB irradiation of a mixture of poly(butyl acrylate) (PBA) modified by acryloyl groups and 2‐[2‐hydrox‐3‐propoxy]ethyl acrylate (HPPA). For the polymer with molecular weight (M̄w) of 10 × 104, the introduction of two acryloyl groups per polymer molecule had the highest peel and dead load strength. On the other hand, for the polymer with M̄w of 3 × 104, five acryloyl groups per polymer gave highest adhesive properties. This difference might be attributed to the entanglement of polymers with high molecular weights. Furthermore, the effect of the addition of polar monomers to the monomer mixture was investigated. Polar groups, such as hydroxyl and carboxyl groups, increased the adhesive properties.
Further characterization of the structure and the thermal transitions of poly(p‐oxybenzoate‐co‐p‐phenylene isophthalate) polymers
Authors: Tsai Hong‐Bing , Lee Chyun , Chang Nien‐Shih , Chen Mei‐Sui , Chang Shinn‐Jen
Published: April 2003

A series of poly(p‐oxybenzoate‐co‐p‐phenylene isophthalate)s were prepared by melt polycondensation ofp‐acotoxybenzoic acid,p‐phenylene diacetate, and isophthalic acid followed by solid‐state polymerization. The solid‐state polymerization not only increased the molecular weight, but also annealed the copolyesters. The thermal stability, liquid crystallinity, thermal properties, and solid‐state crystallinity of these copolyesters were investigated by TGA, polarized microscope, DSC, and wide‐angle X‐ray diffraction, respectively. It was found that copolyesters with HBA content of 50, 60, and 70 mol % showed explicit melt birefringence at 370°C and thus exhibited liquid crystalline state. The effect of annealing during solid‐state polymerization on the thermal properties was discussed. The effect of copolymerization on their crystallinity was interpreted with X‐ray diffraction qualitatively.
Kraft lignin in polyurethanes. II. Effects of the molecular weight of kraft lignin on the properties of polyurethanes from a kraft lignin–polyether triol–polymeric MDI system
Authors: Yoshida Hirohisa , Mörck Roland , Kringstad Knut P. , Hatakeyama Hyoe
Published: April 2003

Polyurethane films were prepared by solution casting using a three‐component system consisting of polymeric MDI, a propylene oxide‐based polyether triol and kraft lignin fractions of different molecular weights. The polyether triol was used as soft segment. The composition of the polyurethanes was varied whereas the NCO/OH ratio was kept constant. The crosslink density increased with increasing molecular weight of the kraft lignin fraction used, which is a result of an increase in functionality of the kraft lignin with increasing molecular weight. Polyurethanes prepared from low molecular weight kraft lignin were found to be more flexible than those prepared from medium and high molecular weight kraft lignin (at lignin contents below 30%). At kraft lignin contents higher than about 30% (which at the NCO/OH ratio used corresponds to a hard segment content of about 70%), rigid and glassy polyurethanes were obtained regardless of the molecular weight of the kraft lignin fraction used.
Flow behaviour of polyblends of crosslinkable polyethylene and silicone elastomer with and without silane coupling agent
Authors: Mukhopadhyay P. , Chowdhury G. , Das C. K.
Published: April 2003

Flow behaviour of melt‐mixed blends of crosslinkable polyethylene (XLPE) and silicone elastomer with and without vinyl silane are studied over the entire composition range. Viscosity and extrudate swelling have been studied as a function of shear rate and processing temperature. The effect of shearing and temperature have pronounced effect as is observed from the data of shear modulus, stored elastic energy, relaxation time, etc. Extrudate surface morphology is studied by scanning electron microscopy. A structure consisting of cross‐linked microgelled silicone elastomer dispersed in continuous XLPE matrix is proposed.
Determination of the composition of post dodecyl benzene by IR spectroscopy
Authors: Beşergil Bilsen , Baysal Bahattin M.
Published: April 2003

The purpose of this study is to determine if the chemical coposition of post dodecyl benzene (PDB) which is obtained as the by product during the production of dodecyl benzene (DDB) at PETKIM, Petrochemical Corporation, is a suitable raw material for the production of alkyl benzene sulphonic acids of high molecular weights. In this work, physical and chemical properties of PDB are determined and results are compared with literature values. Chemical composition analysis are done by IR spectroscopy. Thus, the types of alkylates in PDB are determined both qualitatively and quantitatively, the results showed that PDB consist mainly of mono‐and m‐di‐alkyl benzenes, only a small amount of p‐di‐alkyl benzenes are also present.
Influences of the system pressure and the substrate temperature on plasma polymers
Authors: Ohkubo Junichi , Inagaki Norihiro
Published: April 2003

Plasma polymerizations of aluminium‐acetylacetone (AlAcAc) complex using a magnetically enhanced plasma reaction system were investigated as functions of the system pressure and the substrate temperature. The system pressure and the substrate temperature rather than the RF power played an important role in plasma polymerization reactions. The high system pressure and the high substrate temperature led to bond scission of monomers to yield plasma polymers rich in aluminium moieties. The chemical composition of plasma polymers prepared from AlAcAc complex was discussed from spectroscopic results with FT‐IR and XPS.
A novel method for graft polymerization onto poly(ethylene terephthalate) film surface by UV irradiation without degassing
Authors: Uchida Emiko , Uyama Yoshikimi , Ikada Yoshito
Published: April 2003

A new method omitting oxygen removal procedures from polymerization mixtures was developed for graft polymerization of acrylamide (AAm) onto the surface of poly(ethylene terephthalate) (PET) film with the simultaneous UV irradiation method without photo‐sensitizer. UV irradiation of the PET film with a high pressure mercury lamp under immersion in the 10 wt % aqueous solution of AAm containing an appropriate quantity of periodate (NaIO4) was found to give a highly hydrophilic surface with a water contact angle of about 20°. The original PET film had a contact angle of 75°. In the concentration range of NaIO4 below 1 × 10−4M and above 1 × 10−2 M, polymerization did not take place, whereas polymerization was found to proceed to a significant extent when the NaIO4 concentration ranged between 3 × 10−4 and 5 × 10−3 M. Based on the concentration change of O2 dissolved in the solution during polymerization and the UV spectra of the aqueous AAm solution containing NaIO4 exposed to UV radiation, a reaction mechanism was proposed for the graft polymerization conducted without degassing in the presence of NaIo4.
Rheological behavior of natural rubber latex in the presence of surface‐active agents
Authors: Peethambaran N. R. , Kuriakose Baby , Rajan Manjari , Kuriakose A. P.
Published: April 2003

The rheological behavior of centrifuged and creamed natural rubber latex concentrates and the effect of surface‐active agents such as casein, polyvinyl alcohol (PVA), sodium alginate, and sodium carboxymethylcellulose (NaCMC) were studied at different shear rates and temperatures. The study showed that creamed latex, prepared using tamarind seed powder, is more sensitive to shear rate and temperature than centrifuged latex. The pseudoplasticity and viscosity of the latices can be increased by the addition of surface‐active agents, and the effect varies with the type of surface‐active agents. The behavior of the latices toward temperature is also affected by the addition of surface‐active agents, and maximum effect is observed for polyvinyl alcohol and least for sodium alginate.
Synthesis of organotin polymers from diallyl terephthalate and Bu3SnH
Authors: Moriya Osamu , Endo Takeshi
Published: April 2003

Crosslinked polymers containing both ester and organotin moieties were obtained in high yields from diallyl terephthalate (DATP) and tri‐n‐butyltin hydride via radical processes. The tributyltin ester (1) and the hydrostannated derivatives of DATP (2) were prepared and employed for copolymerizations with DATP. The copolymerizations of 1 and 2 proceeded effectively to afford the corresponding organotin polymers, in which the tributyltin group was incorporated through O–Sn and C–Sn bonds, respectively.
Studies of addition type polyimidesulfones and their composites
Authors: Lee Yu‐der , Ting Mao‐i
Published: April 2003

Addition type polyimidesulfone oligomers have been synthesized from 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride and 3,3′‐bis(aminophenyl) sulfone using three latent crosslinking groups as endcappers. The prepolymers were isolated and characterized for infrared spectra analysis, solubility test in various type solvents, melt flow, and cure properties. The crosslinked polyimides were characterized for thermal stability in a nitrogen atmosphere. The most promising systems, nadimide and maleimide prepolymers, were selected for the detailed study as the matrix for graphite woven cloth reinforced composites for which mechanical and other properties were tested. The differences due to various end‐capped agents, including processibility, the extent of crosslinking of prepolymers, and thermal and mechanical properties of their composites, were compared.
Thermal degradation of functionally terminated polybutadienes: Pyrolysis gas chromatography and thermogravimetric studies
Authors: Rao M. Rama , Radhakrishnan T. S.
Published: April 2003

Thermal degradation of functionally terminated liquid polybutadiene polymers, carboxy‐terminated polybutadiene (CTPB), hydroxy‐terminated polybutadiene (HTPB), and poly(butadieneacrylonitrile‐acrylic acid) terpolymer (PBAN) and their cured analogues were studied by pyrolysis gas chromatography in the temperature range 500–850°C. It was found that CTPB, HTPB, and PBAN could be distinguished from one another by the variation in the composition of their pyrolyzates. The differences in the product composition were rationalized by the relative importance of unzipping and hydrogen transfer reactions in the mechanisms of their degradation. The presence of the OH group was found to favor hydrogen transfer reactions whereas the COOH group has only marginal effect. The cyclization reactions were found to predominate in the thermal degradation of cured PBAN and the pyrolysis results were substantiated by thermogravimetric studies at several heating rates. The activation energy for the decomposition of cured PBAN was estimated to be 259 ± 16 kJ mol−1 by Ozawa's method.
Effect of thermal contacts between components on thermal conductivity of multicomponent systems
Authors: Piorkowska E. , Galeski A.
Published: April 2003

In the paper the influence of thermal contacts of the interface between the inclusions and matrix on thermal conductivity of a multicomponent system is studied. It is shown that the modification of the interface which improves the adhesion between components causes also the increase of the thermal conductivity of a composition.
Properties of mixtures of silk fibroin/syndiotactic‐rich poly(vinyl alcohol)
Authors: Yamaura Kazuo , Kuranuki Noriyasu , Suzuki Miyako , Tanigami Tetsuya , Matsuzawa Shuji
Published: April 2003

The gelation of mixed solutions of silk fibroin (SF)/syndiotactic‐rich poly(vinyl alcohol) (s‐PVA), the thermal analysis of dry‐gels, and the various properties of blend films were investigated. The rate of gelation of a mixed solution was lower than that of each SF or s‐PVA solution of the same concentration. In the DSC thermograph of mixed dry‐gel (SF/s‐PVA = 2/8–8/2) 2 endothermic peaks corresponding to SF (at 288–299°C: decomposition) and s‐PVA (at 233–241°C: melting) were found. Namely, microphase segregation took place. This was confirmed by optical and electron microscopes. The mechanical properties of blend films did not have additive properties. The degree of swelling in water of blend films was independent on water temperature or methanol treatment. The mechanochemical behaviors were barely observed by the pH exchange between pH 2 and 12 only under lower loads. The addition of SF into s‐PVA films promoted the permeation of neutral salts.
Polymeric resins from renewable resources. II. Synthesis and characterization of flame‐retardant prepolymers from cardanol
Authors: Pillai C. K. S. , Prasad V. S. , Sudha J. D. , Bera S. C. , Menon A. R. R.
Published: April 2003

Phosphorylated cardanol prepolymers (PCP) are obtained by simultaneous phosphorylation and oligomerization of cardanol, an unsaturated pentadecylphenol extracted from the nuts of the plant Anacardium occidentale L. Although GPC showed the presence of only oligomeric species in the system, the high viscosity of 0.35–0.45 million cps was found to be due to involvement of hydrogen bonding. IR spectra of PCP gave bands at 1030 and 1240 cm−1, indicating P—O—C linkages. The decrease in iodine value and the absence of vinyl IR bands at 895 and 907 cm−1 indicated oligomerization. NMR spectra of PCP showed partial loss of unsaturation. A carbonium ion initiated mechanism is indicated for the oligomerization. PCP was found to be highly reactive with aldehydes, amines, and isocyanates. Highly insoluble and infusible thermoset products could be obtained. TGA studies showed a two‐stage decomposition with improved thermal stability above 500°C for PCP compared to cardanol‐formaldehyde (novolac)‐type resins. Completely cured PCP was highly resistant to hydrolysis by water. Studies on mechanical properties showed that the PCP cured with HMTA gave a tensile strength of 16.9–21.5 MN/m2 and an impact strength of 1.63–2.04 J. compared to 24–48 MN/m2 and 1.35 J, respectively, for phenol formaldehyde (novolac) resin prepared under similar conditions. The lap shear strength of PCP‐bonded wood pieces showed a value of 400 ± 10 N/cm2 in comparison to 60 ± 10 N/cm2 of cardanol formaldehyde (novolac) resin, indicating that phosphorylation improves the bonding characteristics. With a phosphorus content of 7.9%, PCP showed good fire‐retardant properties. Vertical burning studies did not show any propagation of fire or any afterglow. PCP cured with HMTA gave a limiting oxygen index value of 35, which on bromination increased to 42.0. PCP could find application as polymeric fire‐retardant additive for plastics and elastomers or as filled or unfilled fire‐resistant plastics/composite products.
The effect of γ–irradiation on poly(methyl methacrylate) using an ultrasonic technique
Authors: Aziz A. W. , Abd‐El‐Malak N. A.
Published: April 2003

Ultrasonic absorption measurements were made at 3.14 MHz on poly(methyl methacrylate) as a function of temperature and after various doses of γ‐irradiation. The measurements showed a relaxation phenomenon. The activation energy of the various doses was determined and the smallest doses that affected the specimen was found to be 4 Mrad.
Permeability through cellulose membranes grafted with vinyl monomers in a homogeneous system. VII. Acrylamide grafted cellulose membranes
Authors: Nishioka Noboru , Uno Masakuni , Kosai Kouichi
Published: April 2003

The homogeneous grafting of acrylamide (AAm) onto cellulose was carried out in a dimethyl sulfoxide/paraformaldehyde (DMSO/PF) solvent system. The diffusive permeabilities of solutes through the AAm‐grafted cellulose membranes, apparent activation energy for solute permeation through them, states of water in them, and their microphase separated structures were investigated. The permeability through the grafted membranes was superior to that through the cellulose membrane cast from the DMSO/PF solution of cellulose. The total water contents of the grafted membranes were larger than that of the cellulose membrane. The state of intermediate water in the grafted membranes with fine microphase separated structures was influenced remarkably. A higher activation energy was observed for the solutes with poor permeability through the membranes.
Starch‐derived glycol and glycerol glucosides prepared by reactive extrusion processing
Authors: Carr M. E.
Published: April 2003

Previously, starch‐derived glycol and glycerol glucosides were prepared by batch‐reaction processes and had excellent potential as chemical intermediates for a wide range of products. However, more efficient processes for preparation of these derivatives are needed. In this present work, a modern corotating, intermeshing, twin‐screw extruder with a barrel length/screw diameter (L/D) ratio of 43: 1 was used to study the reaction of starch with ethylene glycol and glycerol in the presence of sulfuric acid catalyst at elevated temperatures. A fully continuous process was used. Variables that were investigated included temperature (140–180°C), glycol or glycerol/starch AGU mol ratio (1.5–4.0), starch feed rate (5–30 lb/h), screw speed (100–475 rpm), residence time, specific energy, and several types of commercial cornstarch and corn flour products. Rates and extents of reaction that occurred in the barrel were determined by analyzing samples that were quenched just prior to extrusion. The major glucosides were quentitated by high‐performance liquid chromatography. Results of this study show that starch can be continuously, rapidly, and efficiently converted to glucosides in 90% yield at high production rates. Such processing is expected to be technically feasible for the reaction of a wide range of polyhydroxy alcohols with various starch substrates.
Interaction of poly(methyl methacrylate) and nafions
Authors: Wilkie Charles A. , Thomsen Jeffry R. , Mittleman Martin L.
Published: April 2003

The thermal degradation of Nafion–H, Nafion–K, and the mixture of each of these with poly(methyl methacrylate) (PMMA) has been studied. A mechanism is proposed for the thermal degradation of Nafion–H that involves an initial cleavage of the carbon–sulfur bond leading to SO2 and OH radical and a carbon‐based radical. This carbon‐based radical then undergoes further degradation. The addition of PMMA to Nafion–H inhibits further degradation of the Nafion carbon‐based radical and instead radical recombination reactions between PMMA fragments and this Nafion radical dominate the reaction scheme. The replacement of the hydrogen in Nafion–H with a potassium (i.e., Nafion–K) produces a much more robust material that does not degrade under conditions similar to those used for Nafion–H. Nafion–K has little effect on the degradation of PMMA.
Complexes of starch polysaccharides and poly(ethylene co‐acrylic acid): Structure and stability in solution
Authors: Shogren R. L. , Greene R. V. , Wu Y. V.
Published: April 2003

Chiroptical methods have been used to study the conformation and interactions of amylose and amylopectin with poly(ethylene co‐acrylic acid) (EAA) in aqueous solution. These studies, along with X‐ray diffraction and solid‐state NMR data, show that amylose and EAA, as well as amylopectin and EAA, form helical V‐type inclusion complexes when mixed in aqueous suspension. This structure apparently accounts for the partial compatibility observed in films containing starch and EAA. About 2/3 by weight of EAA does not interact with amylose and probably represents the ethylene‐rich central core of the EAA micelle. EAA/amylose complexes in 10 mM NaOH were stable to temperatures > 90°C, whereas EAA/amylopectin complexes in the same solvent were largely disrupted at this temperature. Urea, at a concentration of 8 M, further destabilized both EAA/amylopectin and EAA/amylose complexes. Solutions with an alkaline pH (> 9.5) dispersed EAA optimally and allowed maximum complexing with amylose. At pH values > 13, the EAA/amylose complexes were weaker, most likely due to electrostatic repulsion between ionized hydroxyl groups of amylose and carboxyl groups of EAA.
Mechanism of degradation and crosslinking of polyurethane when irradiated by gamma‐rays
Authors: Shintani Hideharu , Nakamura Akitada
Published: April 2003

We conducted a study to clarify the mechanism of crosslinking and degradation of thermoplastic polyurethane (PU) when irradiated with gamma‐rays. Changes in molecular weights as a result of gamma‐ray irradiation, the UV absorption, the amount of PUs with amino groups, and the elution of oligomers to an organic solvent were determined to estimate characteristic changes in PU caused by irradiation. The amount of PUs with primary amino groups as a degradated PU products at p,p′‐methylenediphenyl diisocyanate–1,4‐butanediol (MDI–BU) hard segments increased linearly with increasing irradiation level. The amount of this products by gamma‐ray irradiation was approximately 10–20% of the calculated amount, indicating that predominant degradation occurred at polytetramethyleneglycol (PTMG) soft segments (about 80–90% of the degradation). Characteristic differences were seen in crosslinking between non‐chain‐extended thermoplastic PUs based on the molecular weights of PTMG, (Mw of PTMG = 640–2800). The crosslinking ratio is linearly proportional to the molecular weights of PTMG, indicating that crosslinking at PTMG soft segments was major (the ratio of crosslinking at PTMG was more than 90%). Methanol extract of PU indicated elution of PU oligomers ranging from 13 to 1 as a polymerization degree.
Modification of the dynamic swelling behavior of poly(2‐hydroxyethyl methacrylate) in water
Authors: Kabra B. G. , Gehrke S. H. , Hwang S. T. , Ritschel W. A.
Published: April 2003

The equilibrium and dynamic swelling behavior of glassy polymers immersed in solvents can be modified by controlling the history of the polymer sample, which includes prior swelling and the drying method, or by copolymerization with other monomers. In this paper, the swelling kinetics in water of ionic hydrogels of 2‐hydroxyethyl methacrylate copolymerized with potassium 3‐sulfopropylmethacrylate and/or ethylene glycol dimethacrylate have been studied at 23°C. The dimensional changes of a swelling polymer sheet can be controlled through incorporation of anisotropic stresses in the initially dry, glassy polymer. These anisotropic stresses do not affect the swelling kinetics as long as the sample is partially glassy. However, differences in the initial stresses cause sharply different swelling kinetics once the polymer becomes entirely rubbery, due to differences in dimensional changes. Increasing the percentage of ionic comonomer in the polymer increases the equilibrium degree of swelling and the water sorption rate without changing the time for equilibration or the swelling transport mechanism. In contrast, increasing the percentage of cross‐linker in the polymer not only reduces the degree of swelling and water sorption rate, but also increases the equilibration time and shifts the water transport mechanism from Fickian diffusion to anomalous transport.
Sorption of water by nylon 66 and kevlar 29. Equilibria and kinetics
Authors: Auerbach I. , Carnicom M. L.
Published: April 2003

The sorption of water by nylon 66 and Kevlar 29 fabrics was studied over a range of 20–98% relative humidities at 27°C. Equilibrium and rate relationships were developed from the data in this study and from nylon 66 and nylon 6 data of other studies involving fiber and film. The ratio of sorbed moisture to amide concentration is, on average and at high relative humidities, one water molecule per amide unit. The nylon equilibrium data show that there exist threshold relative humidities above and below which sorption properties differ. One threshold is correlated with the glass transition. Another is identified in the glassy state of nylon 6 in which moisture is tightly bound. The equilibrium constant values are highest and the moisture is most tightly bound at very low humidities, and the values are lowest in the plastic region at high humidities. NMR, DSC, and mechanical property data from others are correlated with the sorption discontinuities observed in this study. Rate data indicate that sorption is a diffusion‐controlled process.
Interactions in the system isotactic polypropylene–calcite
Authors: Rybnikář František
Published: April 2003

Interaction in the system isotactic polypropylene–calcite was investigated using X‐ray diffraction and transmission electron microscopy. Calcite acts as a weak nucleation agent for polypropylene crystallization and its activity could be increased or decreased by a suitable surface treatment. Investigation of the morphology on the polypropylene–calcite interface using calcite single crystals disclosed the tendency of polypropylene for epitaxial crystallization along preferred substrate crystallographic directions. This tendency was analogous to polymer crystallization on other ionic crystals.
Quinone–amine polymers. V. Syntheses and solubilities of several diamine–p‐benzoquinone oligomers (PAQ)
Authors: Nithianandam V. S. , Kaleem K. , Chertok F. , Erhan S.
Published: April 2003

Several diamine–p‐benzoquinone polymer/oligomers were synthesized to find those that exhibited superior properties, in addition to being able to displace water from wet, rusty steel surfaces. Unfortunately, many of these were found to be insoluble in most commonly used solvents and a few to be insoluble in all 34 solvents used in polymer solubility studies. The reason for this low solubility is believed to be the extremely regular structure of the polymers.
Pyrolysis of melamine–formaldehyde and urea–formaldehyde resins
Authors: Hirata Toshimi , Kawamoto Sumire , Okuro Akio
Published: April 2003

Pyrolysis of melamine–formaldehyde and urea–formaldehyde resins in helium and air was investigated by means of TG and gravimetry with isothermal heating, as well as elemental and HCN analyses. Weight loss curves suggest three kinds of reactions involved in the pyrolysis, namely, initiation reactions, reactions splitting off volatile fragments, and reactions forming stabilized structures. In TG, in both helium and air atmospheres, the active weight loss of the melamine resin was completed in two steps, and that of the urea resin was completed in one step, which, however, consisted of a few small successive steps. The isothermal heating weight losses progressed through a few stages of first‐ and zeroth‐order reactions. Arrhenius parameters were obtained for the weight losses in TG and with isothermal heating. The residue from the melamine resin is rich in carbon and nitrogen, and poor in oxygen and hydrogen, while that from the urea resin is rich in carbon, and poor in nitrogen, oxygen, and hydrogen. The effects of temperature on HCN yield changed, depending on the amount of air fed. The melamine resin evolved much more HCN than the urea resin because of the more stable C—N linkages in the resin.
Vinylic graft copolymers of cellulose. II. Thermal degradation of cellulose and its vinylic copolymers and blends by differential scanning calorimetry
Authors: Flaqué C. , Montserrat S.
Published: April 2003

Cotton cellulose with different % NaOH treatments (mercerized), graft copolymers of cellulose prepared with vinyl acetate (VA) and methyl acrylate (MA) and Ce (IV) ions as initiator, and some blends of cellulose–copolymer PVA–PMA were submitted to differential scanning calorimetry (DSC) analysis in nitrogen atmosphere. Two aspects were considered: (a) moisture loss of celluloses with different % NaOH treatments, which showed differences attributed to structural changes in the amorphous region of cellulose‐I and cellulose‐II; (b) thermal degradation analysis of celluloses, their copolymers, and their blends. Experimental results show that thermal stability of celluloses decreases when % NaOH in mercerization increases. For cellulosic vinylic copolymers, the thermal stability increases with the grafting frequency (GF). The blends of cellulose–copolymer PVA–PMA were found to have lower thermal stability than the cellulosic copolymers and the cellulose alone, which was attributed to the acetic acid eliminated in the thermal decomposition of PVA–PMA. The present results seem to be in agreement with the thermal degradation mechanism of cellulose proposed by Patel et al. and provide useful confirmation that the free OH group content is a very important factor in the thermal stability of cellulose.
Distribution of higher‐order structures in injection moldings of particulate‐filled polypropylenes
Authors: Fujiyama Mitsuyoshi , Wakino Tetsuo
Published: April 2003

Flexural test specimens were injection‐molded from polypropylenes filled with flaky talc or spherical calcium carbonate at levels of 0‐40 wt % under cylinder temperatures of 200‐320°C. Distributions in the flow direction of higher‐order structures such as thickness of skin layer, a*‐axis‐oriented component fraction [A*], and crystalline orientation functions and distributions in the thickness direction of higher‐order structures such as crystallinity, β‐crystal content, [A*], and crystalline orientation functions were studied. These higher‐order structures are inhomogeneous in the flow and thickness directions also for injection moldings of particulate‐filled polypropylenes, which strongly influences the product properties such as mechanical and thermal properties. Molecular orientation process in injection molding was theoretically analyzed from a viewpoint of growth of recoverable shear strain at the gate and its relaxation in the cavity, which could considerably well explain the influences of particulate filling and cylinder temperature on not only the mean values but also the changes in the flow and thickness directions, of the quantities such as thickness of the skin layer and crystalline orientation functions, which express the degree of molecular orientation.
Relationship between interchain spacing of amorphous polymers and blend miscibility as determined by wide‐angle X‐ray scattering
Authors: Halasa A. F. , Wathen G. D. , Hsu W. L. , Matrana B. A. , Massie J. M.
Published: April 2003

The average molecular interchain spacing (〈R〉) in Angstroms for amorphous polymers was calculated from the strong maximum in the wide‐angle X‐ray scattering (WAXS) diffraction scan using established equations. The half‐width (HW) of the maximum was used to qualitatively describe the distribution of 〈R〉. 〈R〉 and HW for immiscible blends corresponded to the weighted average of 〈R〉 and HW of the homopolymers in the blend. 〈R〉 for a miscible blend (natural rubber and high‐vinyl PBd) was much larger than the weighted average of 〈R〉 of the component homopolymers, indicating that a new amorphous molecular structure had developed. The larger 〈R〉 for the miscible blend indicates that the molecular chains are spread further apart, resulting in an increase in free volume to accommodate the new packing order. The single Tg of this blend was lower than predicated by the Gordon‐Taylor equation.
Aqueous dispersion of polyurethanes from H12MDI, PTAd/PPG, and DMPA: Particle size of dispersion and physical properties of emulsion cast films
Authors: Kim Byung Kyu , Kim Tae Kyoon
Published: April 2003

Aqueous dispersions of ionic/nonionic polyurethane (PU) were prepared from hydrogenated diphenylemthane diisocyanate (H12MDI), poly(tetramethylene adipate) glycol (PTAd), polypropylene glycol (PPG), monofunctional ethylene‐propylene oxide ether, and dimethylol propionic acid (DMPA). The effects of DMPA, PTAd/PPG ratio, and the average molecular weight of PPG on the state of dispersion, mechanical, and viscoelastic properties of the emulsion cast films were determined using Authosizer, Instron, and Rheovibron.
Electrical conductivity of plasma‐treated poly(p‐phenylene sulfide) doped with iodine
Authors: Tu D. M. , Zhuang G. P. , Kao K. C.
Published: April 2003

Plasma treatment of poly(p‐phenylene sulfide) (PPS) doped with I2 is found to increase both the electrical conductivity and the stability of the material. The average conductivity of plasma‐treated samples reaches an apparently saturated value of 1.7 × 10−3s cm−1, which is about six orders of magnitude higher than that of the same material without plasma treatment, and this conductivity remains practically unchanged under exposure to ambient environment for 10 days. Infrared and secondary ion mass spectra of the samples before and after plasma treatment suggest that the charge‐transfer complexes are formed in PPS doped with I2 after plasma treatment. This is also consistent with the temperature dependence of conductivity results which show that the activation energy for electrical conduction decreases from 2.0 eV for pure PPS to 0.2 eV for plasma‐treated I2‐doped PPS. Using isothermal potential and current decay techniques, we have also measured the trap density distribution. Plasma treatment, on the one hand, does create more traps in PPS, but, on the other hand, it enhances conductivity. The mechanism of electrical conduction is briefly discussed.