bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetic study of polymerization/curing of filament‐wound composite epoxy resin sytems with aromatic diamines
Authors: Golub M. A. , Lerner N. R. , Hsu M. S.
Published: April 2003

The kinetics of the polymerization/curing of an 80/20 blend of a diglycidyl ether of bisphenol A (DGEBA) and a diglycidyl ether of 1,4‐butanediol (DGEBD) with a commercial mixture of methylene dianiline and m‐phenylene diamine (Tonox 60/40) was studied, at amine/epoxy ratios ranging from 1.1 to 4.4. Fourier transform infrared (FT‐IR) measurements were used to follow the extent of epoxy conversion at 18–122°C, and bulk viscosity measurements were used to define the working range of the resin. For an amine/epoxy ratio of 1.1, the activation energy for the polymerization/curing reaction (based on time to 50% epoxy conversion in the S‐shaped conversion‐time plots) was 11.9 kcal/mole by FT‐IR. This value compared favorably with the corresponding value of 12.7 kcal/mole obtained by Moroni and co‐workers in a complementary differential scanning calorimetry (DSC) study of the same system. The FT‐IR conversion‐time plots were fitted to a kinetic expression that can be accommodated by an autocatalytic mechanism; the expression contains two rate constants with activation energies of 13.7 and 10.0 kcal/mole, respectively. The viscosity of the curing epoxy resin was found to obey the Williams‐Landel‐Ferry equation, with a Di Benedetto expression for the glass transition temperature.
Preparation of poly(p‐phenylene terephthalamide)/poly(vinyl chloride) molecular composite and its thermal and mechanical properties
Authors: Yamada Kenji , Uchida Masafumi , Takayanagi Motowo , Goto Kohei
Published: April 2003

Poly(p‐phenylene terephthalamide) (PPTA) was blended with poly(vinyl chloride) (PVC) by solution‐blending method. PPTA was metalated for dissolving in dimethyl sulfoxide. Dimethyl sulfoxide was used as a common solvent. In PPTA/PVC composite, PPTA accelerated the thermal degradation of PVC. PPTA molecules are aggregated as microfibrillar form in PVC matrix. Such microfibrils are dispersed homogeneously in PVC matrix, according to polarizing microscopic observation. The average diameter of the microfibrils becomes smaller in the composite with lower content of PPTA. In the surface region of PPTA microfibrils the intermolecular hydrogen bonds between CCl of PVC and NH of PPTA are formed. Young's modulus and the yield stress at room temperature were higher in the composites than those in PVC. The modulus of the composites was higher, especially at the high temperatures above their glass transition temperatures, than that in PVC. The temperature dependence of modulus can be calculated by using the mechanical model equivalent to the quasi‐3‐dimensional microfibrillar model which will be approximately applied to the composite structure. It becomes apparent that the modulus of the PPTA microfibrils evaluated by using the mechanical model is higher in the higher molecular weight PPTA.
Phase behavior of binary mixtures of styrene/acrylonitrile copolymers and aliphatic polyesters
Authors: Fernandes A. C. , Barlow J. W. , Paul D. R.
Published: April 2003

The phase behavior of binary mixtures of copolymers containing varying amounts of styrene and acrylonitrile (SAN) with a large range of aliphatic polyesters was examined. Miscibility was observed over a limited range of AN contents of the SANs, for each polyester, while similarly for each SAN, miscibility was only observed over a limited range of polyester molecular structures. Thermodynamic interaction parameters for the miscible blends were obtained by analysis of the depression of the polyester melting point. A binary interaction model was used to correlate the data and six group interaction parameters were deduced by subdividing the polyester and SAN copolymer repeating units in three different ways. It is concluded that there is a strong repulsion between the segmental units within the polyesters and within the SAN copolymers, which is an important factor in the observed phase behavior.
New linear polyurethaneureas based on polyoxytetramethylene, aliphatic diisocyanates, and aromatic diamines
Authors: Knaub P. , Camberlin Y.
Published: April 2003

New polyurethaneureas have been synthesized with α‐ω hydroxylated polyoxytetramethylene, aliphatic diisocyanates and nonhalogenated aromatic diamines. Four series of PUR have been studied by varying the PTMO molecular weight, the stoichiometry, the nature of the aliphatic diisocyanate, and the steric hindrance of the aromatic diamine. Quantitative evaluation of the degree of phase separation was obtained by DSC. An estimation of the dispersed soft segments outside the soft phase could thus be made. In addition to DSC, dynamic mechanical properties, were obtained for the four series of PUR over a wide temperature range. The hard segments in the PUR chains are amorphous and their high temperature behavior depends only on the strength of interactions in the amorphous state. Finally, stress‐strain measurements were carried out on a few samples, and a wide range of tensile properties has been observed.
Ternary polymer mixtures: Polyarylate/phenoxy/poly(butylene terephthalate)
Authors: Eguiazabal J. I. , Iruin J. J. , Cortazar M. , Guzman G. M.
Published: April 2003

The intended objective of this work was to bring together two immiscible polymers, polyarylate (PAr) and Phenoxy [poly(hydroxy ether of bisphenol‐A)], preparing ternary mixtures with a third component, poly(butylene terephthalate) (PBT). Experimental results showed that ternary mixtures containing 30% or more PBT gave single glass transition temperatures by DSC. Moreover, the PBT melting point depended on the composition of the mixtures. These results, which could be indicative of the existence of a single amorphous phase in these blends, have been discussed. Nevertheless, results must be considered with caution, given the peculiarities of the Tg–composition diagrams for the miscible pairs PAr/PBT and Phenoxy/PBT. Hypothetic interchange reactions during melting have been found to be unimportant.
Electron diffraction study of enzyme‐hydrolyzed cotton samples
Authors: Paralikar K. M. , Bhatawdekar S. P.
Published: April 2003

An electron diffraction study on continuously and repeatedly enzyme‐hydrolyzed cotton samples was carried out. The electron diffraction pattern on repeatedly enzyme‐treated sample reveals a cellulose I pattern with the absence of the 101 plane. This confirms that enzymatic hydrolysis of cotton fibers proceeds preferentially along the 101 plane, being a clevage plane.
Influence of cure conditions on glass transition temperature and density of an epoxy resin
Authors: Cizmecioglu M. , Gupta A. , Fedors R. F.
Published: April 2003

The glass transition temperature Tg and density of a TGDDM‐DDS epoxy resin system were studied as a function of cure times at various cure temperatures. Both Tg and density asymptotically increased toward a maximum value with increasing cure time. The Tg and density measurements were related to the extent of cure, and the relationship in both cases was found to be independent of cure temperature.
Some aspects on the synthesis and characterization of dodecenyl succinic anhydride (DDSA)—a curing agent for epoxy resins
Authors: Ramaswamy R. , Achary P. Sasidharan , Shine K. G.
Published: April 2003

Dodecenyl succinic anhydride (DDSA), a liquid anhydride curing agent for epoxy resins, was synthesised from C12 olefin and maleic anhydride by the “ene synthesis” reaction. C12 olefin was prepared by the dehydration of lauryl alcohol using Al2O3 (acidic) catalyst. The dehydration was carried out in a flow type reactor. The olefin collected was found to be a mixture of positional isomers of C12 olefin. Systematic studies were carried out by varying the dehydration temperature, mode of feeding and flow rate of lauryl alcohol, and the C12 olefin collected were converted into DDSA and mechanical properties of an epoxy resin–DDSA system were evaluated. The C12 olefins and DDSA were characterized, and the properties correlated with structure and composition. It was found that DDSA derived from C12 olefin with double bond near to the center of the chain gave better tensile strength than the DDSA derived from C12 olefin with terminal double bond.
Structure of fibrous cellulose acetate: X‐ray diffraction, positron annihilation and electron microscopy investigations
Authors: Doyle Stephen E. , Pethrick Richard A.
Published: April 2003

X‐ray diffraction, positron annihilation, electron microscopy and bulk density measurements are reported as a function of the degree of acetylation for a linters cotton. Heterogeneous reaction proceeds with a retention of ordered structure in the fibers. Substitution does increase the extent of disorder but is not sufficiently extensive to disrupt completely order at the fiber, fibril, micro fibril, and crystallite levels. The generation of disorder is associated with an increase in the interfibrillar distance, a breakup of the microfibrillar structure without a total disruption of the microcrystalline structure.
Measurement of polydispersity of ultra‐narrow polymer fractions by thermal field‐flow fractionation
Authors: Schimpf Martin E. , Myers Marcus N. , Giddings J. Calvin
Published: April 2003

In this paper we demonstrate that the polydispersity µ = M̄w/M̄N of narrow polymer fractions can be readily obtained by measuring band broadening and its velocity dependence in a thermal field–flow fractionation (thermal FFF) system. The thermal FFF method is shown to be more accurate than size exclusion chromatography for the determination of polymer polydispersities due to the simpler band dispersion function and the higher selectivity inherent to the technique. The polydispersities of a series of four narrow polystyrene samples prepared by anionic polymerization were consequently determined by thermal FFF and found to be much smaller (1.003–1.006) than the ceiling values (1.06) suggested by the suppliers. As part of this investigation, an experimental study of band dispersion in thermal FFF is used to examine current theory. The data show nonequilibrium to be the dominant factor, whereas relaxation effects are insignificant at lower flow rates and can be subdued at higher flow rates. A high correlation between nonequilibrium theory and experiment allows for the estimation of diffusion coefficients from plate height–velocity data.
The acid‐catalyzed degradation of cellulose linters in distinct ranges of degree of polymerization
Authors: Marx‐Figini M.
Published: April 2003

Cellulose linters with starting degrees of polymerization between 100 < DPn < 6000 had been hydrolytically degraded (0.5 M aqueous solution of KHSO4, degradation temperature 40°C and 60°C) and the results compared with those obtained in a former study on pure cotton cellulose using the same degradation conditions. A complete coincidence in the degradation characteristics of both is shown, distinguishing the latter one by the following features: (1) different kinetic behavior according to the molecular weight range in which degradation takes place; (2) those corresponding to the very high as well as to the very low range of DP reveal a notable decrease of reaction rate; (3) a simultaneous systematic decrease of derivatization capacity occurs in the low molecular weight range; (4) There is no systematic increase of soluble material in the acidic medium with degradation time; (5) in the low molecular weight range, the polidispersity index derived from the molecular weight distributions remains near DPw/DPn = 2.0, except when the hydrolysis had been carried out on already technologically digested materials, causing in these cases a certain increase. The possible reasons for the distinct features of degradation behavior are discussed.
Degradation and cross‐linking of ethylene‐propylene copolymer rubber on reaction with maleic anhydride and/or peroxides
Authors: Gaylord Norman G. , Mehta Mahendra , Mehta Rajendra
Published: April 2003

The reaction of EPR with dicumyl peroxide at 180°C ort‐butyl perbenzoate at 140°C resulted in the formation of a fraction insoluble in cyclohexane at 22°C. The presence of maleic anhydride (MAH) in the EPR‐peroxide reaction mixture increased the amount of insoluble polymer, whose concentration decreased as the peroxide concentration increased. The [η] of the cyclohexane‐soluble polymer decreased and the MAH content increased as the peroxide concentration increased at constant MAH concentration. The [η] and the MAH content of the soluble polymer increased as the MAH concentration increased at constant peroxide concentration. The EPR‐peroxide and EPR‐MAH‐peroxide reaction products were soluble in refluxing xylene and could be fractionated by precipitation with acetone. The presence of stearamide in the EPR‐MAH‐peroxide reaction mixture decreased the amount of cyclohexane‐insoluble polymer, indicative of decreased cross‐linking, but the [η] of the soluble EPR‐g‐MAH increased, indicative of decreased degradation, analogous to the effect of stearamide in the MAH‐peroxide reactions with LDPE and PP, respectively.
Effect of surface treatment of a polymeric filler on its interaction with a plasticizer
Authors: Mikeŝová J. , Hudeĉek S. , Ĉefelín P.
Published: April 2003

The interfacial behavior of a filler–plasticizer system was investigated using the pair poly(sodium methacrylate‐co‐divinylbenzene) beads–diisooctyl phthalate. The effect of various surface treatments of the filler was studied. These consist of a selective extraction of surfactant used in its preparation by emulsion copolymerization and in the adsorption of other types of surfactants. Changes in the compatibility between the two basic components were determined from measurements of the rate of penetration of the plasticizer through the filler bed, from the rheological behavior of concentrated suspensions and from the extractability of the filler from the plasticized PVC matrix.
The phase behavior of ternary blends containing polycarbonate, phenoxy, and polycaprolactone
Authors: Christiansen W. H. , Paul D. R. , Barlow J. W.
Published: April 2003

Ternary blends comprising bisphenol‐A polycarbonate (PC), the polyhydroxyether of bisphenol‐A (Phenoxy), and poly(ε‐caprolactone) (PCL) were found to be generally miscible at PCL levels greater than 60% by weight and to show multiple amorphous phases at lower PCL levels. The melting point depression of PCL in the miscible region of the ternary and in the miscible binary blends with PC and Phenoxy was examined to obtain the enthalpic interaction parameters, Bij, for each of the three binary interactions. The parameters associated with the miscible binary blends were negative, as expected, and indicated that PCL interacts more exothermically with Phenoxy than with PC. The parameter associated with Phenoxy/PC interaction was strongly positive as expected from the complete immiscibility shown by these materials. The interaction parameters were used to calculate the locus of compositions for which the heat of mixing is zero. The locus was found to agree well with the observed boundary between miscible and multiphase behavior in the ternary. This suggests that the phase behavior of ternary blends is largely determined by the same enthalpic considerations known to govern the phase behavior of binary blends.
TPX/siloxane blend membrane for oxygen enrichment
Authors: Lai J. Y. , Wu G. J. , Shyu S. S.
Published: April 2003

The effects of composition, molecular weight, and milling temperature on homogeneity, gas permeability, selectivity of oxygen/nitrogen, and mechanical strength of the TPX/siloxane blend membranes were studied. By adjusting the blending conditions and hence controlling the homogeneity, the gas permeability of TPX membrane was significantly improved without loss of oxygen/nitrogen selectivity. The oxygen permeability of 1.57 × 10−8 cm3 (STP) cm/cm2 s cm Hg and the oxygen/nitrogen permeation ratio of 6.92 can be obtained under the condition of TPX (MX‐001)/siloxane (75,000 MW) = 9/1 at 65°C milling temperature. This membrane possesses 133 kg/cm2 tensile strength and 92% elongation. The morphology of the blend membranes was studied.
Transport of alkali metal ions against its concentration gradient through 2,3‐epithiopropyl methacrylate–methacrylic acid copolymer membrane
Authors: Nonaka Takamasa , Maeda Hirotoshi , Nakayama Morio , Egawa Hiroaki
Published: April 2003

Cationic exchange membranes were prepared with 2,3‐epithiopropyl methacrylate (ETMA)–methacrylic acid (MAc) copolymer. Transport of Li+ against its concentration gradient through the membranes was investigated by using the system containing HCl and LiCl (left side) and LiOH (right side). The rate of transport of Li+ increased with increasing MAc content in the membranes with less than 56.3 mol % MAc. The rate of transport and transport fraction of Li+ could be increased by using the copolymer membranes irradiated with ultraviolet light, because the physical and chemical structure of the membrane made of ETMA–MAc copolymer can be easily changed by irradiation with ultraviolet light. The transport in this system, where one side of the membrane in a cell was acidic and the other alkaline, was influenced significantly by the initial H+ concentration on the acidic side.
Characterization and free radical polymerization of liquid crystalline acrylic acid/cellulose diacetate and N‐vinyl‐2‐pyrrolidinone/cellulose diacetate solutions
Authors: Kozakiewicz Joseph J. , Magniess Jane E.
Published: April 2003

Polymerizations of liquid crystalline solutions of cellulose diacetate (CDA) in acrylic acid (AA) and N‐vinyl‐2‐pyrrolidinone (NVP) were conducted in an attempt to prepare molecular composites (polymer blends) processing a rigid rod polymer with liquid crystalline orientation. CDA was found to form liquid crystalline solutions in both AA and NVP at concentrations avove 40 wt% CDA. Polymerization of anisotropic 50 wt% CDA‐AA and CDA‐NVP solutions occurred with considerable retention of the starting solution anisotropy and yielded homogeneous blends (1 Tg) when the rate of polymerization was fast relative to the phase separation of the free radically polymerizing AA or NVP with CDA. Slow polymerizations lead to phase separated blends (2 Tg).
Kraft lignin in polyurethanes I. Mechanical properties of polyurethanes from a kraft lignin–polyether triol–polymeric MDI system
Authors: Yoshida H. , Mörck R. , Kringstad K. P. , Hatakeyama H.
Published: April 2003

Polyurethanes with various NCO/OH ratios and kraft lignin contents were synthesized by polymerization of kraft lignin (free of the low and high molecular weight fractions), a propylene–oxide‐based polyether triol and polymeric MDI in tetrahydrofuran solution. Films were made by solvent casting and tested with respect to swelling behavior and tensile properties. The main findings were: At low NCO/OH ratios, kraft lignin contributed effectively to the formation of the three dimensional network; under particular conditions of NCO/OH ratio and kraft lignin content, polyurethanes of considerable toughness were obtained; at high kraft lignin contents, the obtained polyurethanes were hard and brittle regardless of the NCO/OH ratio used.
Derivative infrared spectroscopy of cotton cellulose
Authors: Pandey S. N.
Published: April 2003

A new technique of derivative infrared spectroscopy for the study of polymer structure with special reference to cotton cellulose is described. Absorption spectra of cotton cellulose are compared with second deravative spectra. In case of absorption spectra, while determining the wavelength and intensity of a given absorption, in many cases, difficulties arise due to the presence of an interfering band which, as a consequence of overlap, prevents the determination of the above properties. Derivative spectroscopy provides valuable information on structural properties of cellulose. It yields spectra gradient, which facilitates the separation of overlapping absorption bands to resolve and detect absorptions; neither were unresolvable as a consequence either of multiple bands overlap or of low intensity. Hence, the measured wavelength in the second derivative spectra are more precise than the absorption spectra. For fine structural studies of cellulose, derivative spectra may provide more useful information as the absorption bands are more clearly defined.
The dynamics of the continuous emulsion polymerization of methylmethacrylate
Authors: Schork F. J. , Ray W. H.
Published: April 2003

Experimental data on the dynamics of the continuous emulsion polymerization of methylmethacrylate are presented. Techniques for on‐line reaction monitoring and digital data acquisition as reported previously are used to generate dynamic data on the monomer conversion and free emulsifier concentration. Data are reported confirming the existence of multiple steady states and limit cycles in the CSTR (continuous stirred tank reactor) emulsion polymerization of methylmethacrylate. Data are also reported suggesting the presence of steady states in the absence of micelles in the reactor. The possible causes of these phenomena, and the conditions under which they occur are discussed.
Thermal conductivity of a polymer composite filled with mixtures of particles
Authors: Agari Y. , Tanaka M. , Nagai S. , Uno T.
Published: April 2003

A new thermal conduction model is proposed for a polymer system filled with a mixture of several types of particles. Predicted values by the new model are compared with experimental data. The model is derived by extending a model that was previously proposed for a two‐phase system. The following equation is derived from the new model: log λ = V · (X2 · C2 · log λ2 + X3 · C3 · log λ3 + (1 − V) log (C1 · λ1. When the thermal conductivities of polymer and particles (λ1, λ2, λ3, …) and a mixing ratio of particles (X2, X3, …) are known, thermal conductivity of the filled polymer (λ) with several types of particles can be estimated from the equation, with any volume content of particles (V). Furthermore, from each polymer–filler composite (two‐phase system) data, the thermal conductivity of a composite filled with different filler particles can be estimated.
Phosphorescence and fluorescence of poly(vinyl alcohol) films
Authors: Mieloszyk January , Drabent Regina , Siódmiak Józef
Published: April 2003

Luminescence properties of poly(vinyl alcohol) (PVA) films were investigated at room and low (103 K) temperatures. It was estimated that the PVA films can be regarded as luminescentless matrices when excited by radiation of wavelengths greater than 420 nm (λexc≥ 420 nm).
New epoxy‐imide resins cured with bis(hydroxyphthalimide)s
Authors: Ichino Toshihiro , Hasuda Yoshonori
Published: April 2003

New epoxy‐imide resins were synthesized using bis(hydroxyphthalimide)s (BHPIs). Among these resins, that cured with BHPI(DDS), synthesized from 4,4′‐diaminodiphenylsulfone, exhibits the best thermal resistance, reaching a tan δ maximum temperature of 230°C. This resin also features a tensile lap shear adhesive strength of 320 kgf/cm2 when applied to steel test pieces. The cure reaction was followed by infrared spectroscopy and dynamic mechanical analysis. The ring‐opening reaction between the phenolic hydroxyl group of BHPI and the epoxy group is observed, and accelerated by a tertiary amine catalyst, triethylamine.
Flame retardation of polypropylene: Effect of organoantimony compounds on the structural and mechanical properties
Authors: Bajaj P. , Jha N. K. , Maurya P. L. , Misra A. C.
Published: April 2003

Structural properties of polypropylene (PP) filled with flame‐retardant (FR) organoantimony compounds, viz., triphenylstibinedibromide and triphenylantimony (V) derivatives of tribromotrichloro‐, and pentachlorophenols at 5–20 phr additive loading, were investigated through differential thermal analysis (DTA), and X‐ray diffraction (XRD) studies. Incorporation of flame retardant in PP has decreased the melting temperature (Tm) and heat of fusion (ΔHf) of PP. Crystallization peak and the onset temperature, crystallization rate and crystallite size are also influenced by the addition of these compounds. The percent crystallinity obtained by XRD is in good agreement with that obtained by DTA. The tensile properties of the flame‐retardant‐filled PP are also studied, and an attempt has been made to correlate the tensile properties with that of structural changes in polypropylene. Fracture mechanism of flame‐retardant‐filled PP has been investigated with the help of a scanning electron microscope.
Diffusion of miscible polymers in multilayer films
Authors: Keskkula H. , Paul D. R. , Young P. , Stein R. S.
Published: April 2003

Thermal and optical properties of multilayer films of miscible polyethyloxazoline (PEOx) and poly(styrene‐co‐acrylonitrile) have been studied as a function of time and temperature. Differential scanning calorimetry showed that the distinct, characteristic Tg's of the component polymers of the original films disappear after only short heating periods above Tg, and a single transition appears. The new transition region is broad at first, but narrows on subsequent heating. The measurement of light transmittance as a function of wavelength through the heat‐treated films also confirms the diffusion of the miscible polymers and gives results which are comparable to the thermal measurements. Films from immiscible polymers of polystyrene and PEOx retain their properties after various heat treatments. A qualitative discussion of the diffusion process as examined by the thermal measurements is presented.
Polycarbonate‐polyurethane semi‐interpenetrating polymer networks: Tg behavior and morphology
Authors: Shyu S. S. , Chen D. S. , Lai J. Y.
Published: April 2003

The dynamic mechanical properties, transition behavior, and morphology of polycarbonate (PC)‐polyurethane (PU) semi‐interpenetrating polymer networks (semi‐IPNs) and linear blends were studied by means of Rheovibron, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). Two glass transition temperatures corresponding to polycarbonate and polyurethane were observed and microphase separation was further evident with TEM. In PC/PU semi‐IPNs, two glass transition temperatures were shifted inwardly indicating that the interpenetrating network of polyurethane increases the mutual miscibility of PC and PU. The average phase domain was 500Å in semi‐IPNs and the phase domains were in the range 1000–6000 Å in linear blends of the corresponding polymers. The compatibilities of PC and PU were greatly influenced by the molecular weight of polyols in PU prepolymer and the ratio of NCO/OH; lower molecular weight polyols and higher NCO/OH ratio resulted in better compatibility, and finer phase domains in PC and PU linear blends and semi‐IPNs.
Effects of trans‐polyoctenylene on the mechanical properties of NBR
Authors: Björk Folke , Stenberg Bengt
Published: April 2003

Trans‐polyoctenylene (TOR), a high‐polymer polymerization product of cyclooctene, has found use as a processing aid in high‐viscosity rubber stocks. We have compared some physical and mechanical properties of a NBR‐compound with TOR with those of the same compound without TOR. Mooney viscosity was lower for the compound with TOR. Cylinders with a height and diameter of 20 mm were molded. It was found that stress–relaxation measured in the common static way was almost the same for the two compounds. Dynamic stress–relaxation occurred much more rapidly for the compound with TOR. The compound with TOR increased in hardness more rapidly when aged in air, and showed a higher swelling in oil. The DSC results imply that TOR is incorporated as a separate phase in the parent rubber. The sealing properties are affected detrimentally when TOR is used as a processing aid in NBR.
The graphical evaluation of ionic dye sorption isotherms using dimensionless groups
Authors: McGregor Ralph , Tamura Keiko , Iijima Toshiro
Published: April 2003

A graphical method is proposed for the analysis of experimental data on the equilibrium sorption of ions by charged polymers. The method uses dimensionless groups of variables, which are based on a generalized Donnan theory. Graphical comparisons of theoretical curves with experimental data‐point sets permit rapid estimation of theoretical parameters. The use of dimensionless groups clarifies the complex interactions between the individual sorption variables. This simple procedure consists of relative lateral and vertical displacements of the data point graphs and the theoretical graphs along their coordinate axes. The graphical comparisons help to reveal the nature of departures from the basic theoretical model. Examples of the method are given for oxycellulose/methylene blue and polyacrylonitrile polymer/cationic dye systems.
Anisotropic reinforcement in elastomers containing magnetic filler particles
Authors: Sohoni G. B. , Mark J. E.
Published: April 2003

Magnetic particles of iron oxide were blended into portions of a high molecular weight sample of poly(dimethylsiloxane) which were then peroxide cured in a magnetic field. Strips cut from the resulting elastomers parallel and perpendicular to the magnetic lines of force were studied with respect to their equilibrium swelling and their stress–strain isotherms in elongation. Both resistance to swelling (as measured by the volume fraction of polymer in the network) and the elongation modulus increased with increase in the amount of filler. They were also generaly larger in the direction parallel to the field, and the differences increased both with increase in the amount of filler and with increase in the strength of the magnetic field. Stress relaxation also increased with amount of filler and field strength, thus illustrating the importance of adsorption of the polymer onto the filler particles, and its subsequent desorption under stress.
Copolymerization of vinyl chloride with 1‐olefins. Part IV. Investigation of rheological and mechanical properties of copolymers
Authors: Mrázek Zdeněk , Kolínský Miloslav , Horáček Ivan , Černoch Jan
Published: April 2003

Copolymers of vinyl chloride with propene, 1‐butene, and 1‐pentene having the same content of 1‐olefin (4.0 ± 0.5 mol%) and various molar mass and copolymers with a comparable molar mass and the same composition were prepared. By measuring rheological and mechanical properties of this assembly of samples, which also included the reference vinyl chloride homopolymer, it was possible to estimate the effect of molar mass and of the individual comonomers. The copolymers under investigation possessed improved processing properties and did not suffer any deterioration of important mechanical properties.
Structure and properties of p‐carboxysuccinanilic polyester resins
Authors: Nosseir Michael H. , Doss Ninette L. , Taufik Sohair Y.
Published: April 2003

Polyester resins were prepared by the reaction of p‐carboxysuccinanilic acid ethyl ester with ethylene glycol and 1,4‐butenediol. Also, unsaturated polyester resins were prepared by the copolymerization of p‐carboxysuccinanilic acid ethyl ester and maleic anhydride with ethylene glycol, 1,6‐hexanediol, 1,4‐butenediol, and 2‐butyne‐1,4‐diol. All the polyester resins and the copolyesters have been characterized and were found to cure with styrene, except those prepared in the absence of maleic anhydride. The properties of the cured products in the form of films were determined. Infrared and nuclear magnetic resonance (NMR) spectroscopy were used for both qualitative and quantitative analyses of the polyester resins and their hydrolyzate products after curing with styrene.
Polyurethane‐based sealants modified by blending with Kraft lignin
Authors: Feldman D. , Lacasse M. , St. J. Manley R.
Published: April 2003

An investigation was conducted to establish the viability of blending Kraft lignin (L), a naturally occuring, readily available polymer resource, with polyurethane‐(PU) based sealants. The sealants were tested in a detailed program where lignin‐sealant blends, having blend ratios varying between 0 and 20 pbw L, were prepared on substrates of aluminum, mortar, and wood, and subjected to laboratory control (C), artificial weathering (AW), and natural weathering (NW) conditions. Results of tension testing showed that generally, lignin acts as a reinforcing agent which adds rigidity to the polymeric matrix, as indicated by the increase in toughness and modulus of blended sealants with the addition of lignin. In addition, the curing mode of PU, as determined by sequence hardness testing, was modified with the addition of lignin.
Packing density of the amine‐crosslinked stoichiometric epoxy networks
Authors: Bellenger V. , Dhaoui W. , Morel E. , Verdu J.
Published: April 2003

The packing densities (Van der Waals volume/molar volume) were determined at 293 K for various epoxide–amine stoichiometric networks. They are noticeably higher than those of linear polymers except strongly hydrogen bonded ones [polyamides, poly(vinyl alcohol)]. By extrapolation of the dilatometric data, it was found that the packing densities at the frontiers of the glassy state (0 K and Tg) of the epoxy networks are comparable to those of linear polymers having the same theoretical hydrogen bond density (polyamides). However, for a given packing density at 0 K, the packing density at Tg is higher for a network than for the corresponding linear polymer.
Preparation of quinazolone–imide copolymers and their thermal and chemical etching properties
Authors: Kubota Shigeru , Ando Torahiko
Published: April 2003

Quinazolone‐imide copolymers were prepared by polycondensation of 6,6′‐methylenebis(2‐methyl‐3,1‐benzoxazine‐4‐one) and 3,3′,4,4′‐benzophenonetetracarboxlic dianhydride and 4,4′‐oxydianiline. Their thermal properties by TGA and their chemical etching properties by the use of the etchant composed of hydrazine hydrate and ethylenediamine were studied. The copolymers obtained had good solubility and excellent heat resistance and gave flexible and tough films. The chemical etching properties were more subject to influence of the polymer composition than the thermal properties were.
Polyester polyols for polyurethanes from pet waste: Kinetics of polycondensation
Authors: Vaidya U. R. , Nadkarni V. M.
Published: April 2003

The kinetics of polyesterification of the glycolyzed PET waste with adipic acid is reported. Glycolysis of PET waste was carried out with ethylene glycol at three different ratios of PET waste to glycol. The glycolyzed products could be readily polyesterified by reacting with adipic acid, to give polyester polyols with low acid number. Kinetics of polyesterification of the glycolyzed product made from 62.5% ethylene glycol (EG) and 37.5% waste were investigated further at different hydroxyl to carboxyl ratios. Reaction conditions were nonisothermal, comparable to the industrial process scheme consisting of two isothermal regions at 170° and 200°C. The kinetic results of the polyesterification of glycolyzed PET waste are compared to the polyesterification of pure diols, namely ethylene glycol and bis(hydroxyethyl) terephthalate (BHET) with adipic acid. The reactions follow second‐order kinetics at 170°C and the rate of polyesterification of the mixed diol system from PET waste lies intermediate between those of the pure diols, namely, EG and BHET. Ethylene glycol exhibited the highest reactivity. At 200°C the kinetic plots of the mixed diols from PET waste were nonlinear, and thus the reaction may not follow second‐order kinetics. The nonlinearity is explained in terms of the different reactivities of the different diol species in the reaction mixture. The polyester polyols, when cured with polymeric 4,4′ diphenyl methane diisocyanates, gave polyurethane rigid foams and elastomers.
13C‐NMR characterization of poly(1,5‐hexadiene)
Authors: Cheng H. N. , Khasat N. P.
Published: April 2003

Poly(1,5‐hexadiene) was prepared and its structure characterized by high‐field 13C nuclear magnetic resonance. The polymer was shown to contain repeating five‐membered rings separated by methylene bridges, with both cis and trans placements present in a 54 : 46 ratio. The result is compatible with the Marvel‐Garrison two‐step reaction mechanism.
Processing–structure–property relationships in poly(ethylene terephthalate) blown film
Authors: Ma Tung Chan , Han Chang Dae
Published: April 2003

An investigation was undertaken to establish processing–structure–property relationships in poly(ethylene terephthalate) (PET) blown film. For the study, a commercial grade of PET was used to fabricate the film specimens by means of a tubular film blowing process. In this process, the stretch temperature was accurately controlled by an oven. The annealing treatment of the oriented specimens involved clamping the sample in an aluminum frame and then putting the clamped sample in an oven, controlled at a temperature between the glass transition temperature (70°C) and the melting point (255°C) of PET, for a specified annealing period. The structure of the blown film samples was characterized by density, bulk birefringence, flat plate wide‐angle X‐ray scattering, and pole figure analysis. The processing variables, namely, takeup ratio, blowup ratio, and stretch temperature were found to significantly affect the bulk birefringence and density of the oriented PET blown film samples. It was found that both the bulk birefringence and density of the specimens increased upon annealing at an elevated temperature. Both the crystalline and amorphous orientation functions were calculated from the data of bulk birefringence, density, and the pole figure analysis. Compared to the amorphous orientation functions, the crystalline orientation functions were found to be relatively insensitive to the processing variables. It was concluded that equibiaxially oriented PET films can be produced via a tubular film blowing process by judiciously controlling the processing and annealing conditions. It has also been observed that the tensile stress‐at‐break of equibiaxially oriented PET film increases with decreasing stretch temperature and increasing annealing temperature.
Low‐density polyethylene depth profile analysis by photoacoustic spectroscopy
Authors: De Oliveira Marcelo Ganzarolli , Pessoa Osvaldo , Vargas Helion , Galembeck Fernando
Published: April 2003

Near‐infrared photoacoustic spectra of polyethylene (1 mm slab) were taken in the modulation range 10–240 Hz, which corresponds to thermal diffusion layers in the 56−11 μm range. Thick‐layer spectra are very similar to polyethylene film transmission spectra, but large differences are observed between the spectra taken at various modulation frequencies. From 10 to 80 Hz, all the spectral band intensities decrease linearly with ω−a where ω is the light modulation frequency and a varies from 0.48 to 1.00 for different constituent groups. The analysis of spectral intensity as a function of modulation frequency shows that peak intensity ratios of CH3, CH2, and OH groups, relative to that of methylene groups, increase as thinner, closer‐to‐surface polymer layers are sampled. From this we conclude that near‐to‐surface layers of solid polyethylene are richer in CH3, CH2 and OH groups than the polymer bulk.
Miscible blends of poly(aryl ether ketone)s and polyetherimides
Authors: Harris J. E. , Robeson L. M.
Published: April 2003

A new class of high performance engineering resins, poly(aryl ether ketone)s, has emerged with a property balance not offered by existing polymeric materials. Blends of poly(aryl ether ketone)s with other polymers have not been described in the open literature, although several patents have revealed interesting and important properties of certain blend combinations. Ultem polyetherimide has been found to be miscible over the entire composition range and as a consequence is a very effective heat distortion temperature builder, particularly if the poly(aryl ether ketone) is allowed to crystallize. Crystallization kinetics and mechanical properties were studied as a function of blend composition and poly(aryl ether ketone) melting point. The blends exhibited a maximum in toughness at intermediate compositions along with an accompanying maximum in poly(aryl ether ketone) crystallinity. The chemical resistance of the polyetherimide is significantly improved with the addition of a poly(aryl ether ketone). In organic chemicals, the improvement was expected when tensile stress was plotted vs. log time to rupture. However, in aqueous bases, the resistance of the blends was much greater than anticipated. This property profile suggests that these blends will be useful as thermoplastic composite matrix resins.
Synthesis and properties of elastomeric ionenes I. Polybutadiene ionenes
Authors: Yamashita Shinzo , Itoi Masaaki , Kohjiya Shinzo , Kidera Akinori
Published: April 2003

Polybutadiene ionene (PBI) carrying quaternary ammonium ions in the main chain was synthesized from dimethylamino‐terminated polybutadiene and 1,4‐dibromobutane. Dimethylamino‐terminated polybutadiene was prepared by the reaction of isocyanate‐terminated polybutadiene with 2‐dimethylaminoethanol. The swelling property and the mechanical properties of PBI were compared with those of polybutadiene urethane (PBU), which was prepared by the reaction of hydroxy‐terminated polybutadiene with a diisocyanate. The following points were found: (1) PBI shows almost the same solubility parameter δp as that of PBU; (2) PBI attains a four time greater tensile strength at break than PBU at room temperature; (3) PBI shows a thermoplastic behavior.
Rheological properties and crystalline structure of the dynamically cured EPDM and PP/HDPE ternary blends
Authors: Ha Chang Sik , Kim Sung Chul
Published: April 2003

The rheological properties and crystalline structure of the polyolefin ternary blends of EPDM/polypropylene/high density polyethylene were studied. Blends were prepared in a laboratory internal mixer by two different methods. In blend–cure process, blending and curing were performed simultaneously and EPDM was cured by dicumyl peroxide (DCP) in the presence of PP/HDPE under shear. The cure–blend was to cure EPDM alone first under shear (dynamic curing) and then mix the cured EPDM with PP and HDPE. The effect of DCP concentration, intensity of the shear mixing, and the rubber/plastic composition were studied using capillary rheometer and X‐ray diffractometer. The PP‐rich ternary blends showed the effect of the mechanooxidative degradation of PP by shear and peroxide. The melt viscosity increased with increasing DCP concentration in blends of EPDM‐rich compositions. X‐ray diffraction studies revealed that the inclusion of 25 wt % of linear EPDM in the PP/HDPE mixture for the PP‐rich ternary blends changed the crystal structure of polypropylene component in the ternary blends. However, the dynamic curing did not alter the crystal structure of PP or HDPE in the blends.
The use of infrared spectroscopy for determination of polypropylene stereoregularity
Authors: Burfield David R. , Loi Patrick S. T.
Published: April 2003

This study examines the application of infrared (IR) spectrometry to the determination of polypropylene (PP) stereoregularity. The use of the absorption bands at 998 cm−1 and 841 cm−1 as indices of isotacticity and bands at 1167 cm−1 and 973 cm−1 as internal references have been explored. Calibration curves relating various absorption ratios to isotacticity as measured by 13C nuclear magnetic resonance are reported. The ratios A998/A973 and A841/A973 are the most useful and provide linear correlations with isotacticity. The effect of instrument type on the calibration has been investigated for both dispersive and Fourier transform type IR spectrometers. For samples annealed at room temperature the average of measurements on the same set of PP films by five instruments provide the calibrations: A998/A973 = 1.08 ± 0.02 (mm)−0.15 ± 0.03; and A841/A973 = 0.84 ± 0.06 (mm)−0.04 ± 0.02. High temperature annealing increases the crystallinity of the samples and the corresponding value of the absorption ratio but is not necessary for obtaining reproducible calibration curves.
Stress relaxation studies of model silicone RTV networks
Authors: Stein Judith , Prutzman Lori C.
Published: April 2003

The stress relaxation behavior of model silicone room temperature vulcanizing (RTV) elastomers has been used to examine the chemistry of the cured silicone network. It has been shown that the tin crosslinking catalyst, together with water, produces siloxane bond rearrangement which results in chemical stress relaxation. The measurement of the rate of stress relaxation of unfilled model elastomers at various temperatures gave an apparent activation energy of 10.3 kcal/mole−1 for the relaxation process. In addition, the effects of some of the constituents of the RTV on relaxation behavior have been examined.
Study on rough‐surface biaxially oriented polypropylene film. II. Influence of stretching conditions
Authors: Fujiyama Mitsuyoshi , Kawamura Yoshimasa , Wakino Tetsuo , Okamoto Tomomi
Published: April 2003

The production of rough‐surface biaxially oriented polypropylene film (BOP) has been studied by means of casting a polypropylene which contained γ‐quinacridone, a β‐crystal nucleator, with a T‐die extruder into a sheet which has subsequently been stretched successively in the machine direction (MD) and the transverse direction (TD) with a roll‐type stretching machine and a pantograph‐type stretching machine, respectively. For roughening of BOP using β‐form crystals in a successively stretching tenter method, it is preferable to roughen in the MD‐stretching process, with suppression of the recrystallization into the α crystals after melting of the β crystals being the most important objective. By rapid heating of a cast sheet in the MD‐stretching process, a rough‐surface BOP with a crater‐like roughness was obtained. Theoretical proof for the effectiveness of the rapid heating in the MD‐stretching process was obtained from experiments on the melt‐transformation of the β crystals by differential scanning calorimetry (DSC) measurements.
Irradiation of solvent‐treated cotton fibers
Authors: Rabie S. M. , Abd‐El‐Nour K. N. , Moharram M. A.
Published: April 2003

The infrared spectra and dielectric properties of cotton fibers pretreated for one day with toluene, methanol, and mixtures of the two have been investigated after drying the samples for 1 and 4 days. The effect of γ‐radiation on the crystallinity and dielectric properties of the solvent‐treated was examined. The samples were irradiated in air and also in the presence of the solvents. The data obtained indicate that the addition of toluene to methanol increases the rate of uptake of methanol by cotton. Moreover, it is found that irradiation of cotton fibers in the presence of toluene assists the oxidation of the cotton while irradiation in the presence of methanol reduces the oxidation effects of γ‐radiation.
Ductile transition in nylon‐rubber blends: Influence of water
Authors: Gaymans R. J. , Borggreve R. J. M. , Spoelstra A. B.
Published: April 2003

On nylon 6 and nylon 6/EPDM blends the influence of water on the glass transition temperature, mechanical properties, and the ductile transition temperature was studied. Blends of 10% and 20% were prepared with a particle size of 0.3 μm and the tensile properties, flexural moduli, torsion moduli, and notched izod impact strength were studied as functions of water concentration. The ductile transition temperature in polyamides can be lowered by plasticizing the nylon and by a rubber particle‐induced process; both processes show some synergistic effects.