bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics of epoxy resins formation from bisphenol‐A, bisphenol‐S, and epichlorohydrin
Authors: Jungang Gao
Published: April 2003

The kinetics of formation of epoxy resins derived from bisphenol‐A, bisphenol‐S, and epichlorohydrin under stoichiometric conditions was considered. The kinetics of reaction was studied by taking into account the consumption of the added alkali and epoxide value of epoxide oligomers. The obtained results satisfactorily explained that the reactivity of bisphenol‐A with epichlorohydrin is higher than that of bisphenol‐S, the rate of dehydrochlorination of chlorohydrin ether in the presence of alkali and water is much higher than that of the rate of condensation of phenolic hydroxyl group with epichlorohydrin. The apparent reaction order of phenolic groups with epichlorohydrin and terminal epoxide group in the oligomer are all second order. The rate constants and activation energy were determined. The results are discussed. © 1993 John Wiley & Sons, Inc.
Structure‐property relationship of HTPB‐based propellants. II. Formulation tailoring for better mechanical properties
Authors: Manjari R. , Somasundaran U. I. , Joseph V. C. , Sriram T.
Published: April 2003

There has been a constant endeavor to improve the mechanical properties of hydroxylterminated polybutadiene (HTPB) ‐based composite solid propellants. A systematic study has been conducted on different batches of HTPB resins with varying molecular weights and hydroxyl values. Propellant formulation experiments were conducted wherein the ratio of chain extender to crosslinker was systematically varied, with a view to achieve the maximum possible strain capability and moderately high tensile strength, keeping all other parameters constant. The influence of increasing hydroxyl content from trimethylolpropane at the expense of hydroxyl content from butanediol, on the mechanical properties of the finished propellant, has been depicted on 3‐dimensional graphs. The isoproperty lines, plotted as a triangular chart with the percentage hydroxyl contents from the three constituents, can be used to arrive at the suitable formulation for a specified application depending upon the OH value of the resin. HTPB resins with high molecular weight, low functionality, and low hydroxyl value require higher levels of trifunctional curing agent and higher NCO / OH ratios to obtain outstanding mechanical properties, especially elastic properties, compared to low molecular weight, high functionality resins. The impact of hard and soft segment domain structure on the mechanical behavior of the cured systems is more pronounced in the low molecular weight resin formulations due to the higher hard segment content compared to those attainable in high molecular weight resin formulations. © 1993 John Wiley & Sons, Inc.
The removal of color from effluents using polyamide‐epichlorohydrin‐cellulose polymer. I. Preparation and use in direct dye removal
Authors: Hwang M. C. , Chen K. M.
Published: April 2003

A novel series of adsorbents have been prepared by reacting adipic acid, diethylenetriamine, epichlorohydrin, and cellulose. The structural features of these polyamide‐epichlorohydrin‐cellulose (PAE‐Cell) polymers have been confirmed by IR analysis. The ability of PAE‐Cell polymers to adsorb direct dyes from aqueous solution has been evaluated in a fixed bed column system. These PAE‐Cell polymers have been found to exhibit a better capacities for direct dye removal than some commercial activated carbons.© 1993 John Wiley & Sons, Inc.
Water penetration in glassy polymers: Experiment and theory
Authors: Best M. , Halley J. W. , Johnson B. , Vallés J. L.
Published: April 2003

We describe the design and implementation of a method based on infrared monitoring of the OD stretch mode which permits measurement of the diffusion profiles of water permeating glassy polymers for the first time. Results for several glassy polymers are compared with a theory of trapping diffusion which leads to a nonlinear diffusion problem in which the trapped water penetrates the polymer as a sharp front if there is a large amount of trapping. In the case of two of the polymers studied, the trapping model describes the data, very well (much better than a simple diffusion model) and permits determination of parameters related to the free volume and the residence time of the water on traps in the model. © 1993 John Wiley & Sons, Inc.
Molecular weight estimation by pressure during polymerization
Authors: Otake Katsuto , Yasuda Toshiyuki , Aihara Akio , Yokoyama Chiaki , Takahashi Shinji
Published: April 2003

Experimental studies for the mol wt estimation by pressure was performed with a batch polymerization of phthalic anhydride (PA) and ethylene glycol (EG). Experimental results show that the pressure in the reactor can be utilized to estimate the mol wt of products. © 1993 John Wiley & Sons, Inc.
Primers for adhesive bonding to polyolefins
Authors: Yang Jiyue , Garton Andrew
Published: April 2003

When polypropylene (PP) and low density polyethylene (LDPE) are coated with about 100 nm of triphenylphosphine (TPP) or cobalt acetylacetonate (CaAcac2) primers, adhesive bonds can be made using ethyl cyanoacrylate (CA) adhesive. These bonds are sufficiently strong so that the bond strength exceeds the bulk shear strength of the polyolefin, and are sufficiently durable as to withstand immersion in boiling water for long periods of time. The dependence of adhesive bond performance on primer thickness, application solvent, aging of primed surface, and the durability of bond, are explained on the basis of a model where the primer dissolves in the polymer surface and facilitates interpenetration of the polyolefin and the monomeric CA. The primer catalyzes cure of the CA, resulting in entanglement of adhesive and adherend chains. This model is tested using infrared (IR) spectroscopic, x‐ray spectroscopic (XPS), and microscopic (SEM) analysis. © 1993 John Wiley & Sons, Inc.
Preparation and characterization of polystyrene terminated with an organic sulfide group and styrene–vinyl acetate block copolymer
Authors: Liu Fu‐Tian , Cao Shu‐Qin , Yu Xian‐Da
Published: April 2003

Polystyrene terminated with an organic sulfide group was prepared by styrene bulk polymerization using three organic disulfides as initiators, and the content of the organic sulfide group (X̄n) was determined quantitatively from the data of UV and M̄n.

Styrene–vinyl acetate block copolymer was prepared by using polystyrene ended with the organic sulfide group as the photosensitizer to initiate vinyl acetate polymerization. The copolymer was characterized by IR, 1H‐NMR, 13C‐NMR, DSC, and TEM, respectively.

Different copolymerization conditions were investigated systematically. The result reveals that the X̄n value is a key factor in the copolymerization and the copolymerization proceeds via living radical mechanism. © 1993 John Wiley & Sons, Inc.
A study of rheological properties and crystallization behavior for HDPE melts during extrusion
Authors: Ness J. N. , Liang J. Z.
Published: April 2003

The influence of temperature and shear rate on the flow behavior of high density polyethylene (HDPE) melts during extrusion has been investigated by using a Ceast Rheovis 2100 capillary rheometer which was manufactured by the Ceast Co. in Italy. It was found that the entry pressure drop for the samples was very low during extrusion, the relationship between shear stress and shear rate did not obey the power law strictly, and the phenomenon of shear‐induced crystallization was easily produced when temperature was near the melting point of the samples, even though the shear rate was not high. The dependence of the shear viscosity for the samples on temperature can be described by using the Arrhenius equation. © 1993 John Wiley & Sons, Inc.
Morphological origin of super toughness in poly(ethylene terephthalate)/polyethylene blends
Authors: Carté Theresa L. , Moet Abdelsamie
Published: April 2003

A compatibilization strategy for poly(ethylene terephthalate) (PET) and polyethylene (PE) blends to achieve high toughness is described. Maleic anhydride functionalized styrene–ethylene–butylene–styrene (MA‐g‐SEBS) block copolymer at 20 pph was found to produce an intricate multidomain morphology in which the two major components (50% PE, 50% PET) and the compatibilizer coexist on a hierarchal order. A portion of the PET was dispersed as interconnected rodlike domains oriented along the injection direction. The rest of the PET and the PE constituted beadlike nano domains which served as the matrix. The blend at all these morphological levels responded to deformation in a cooperative fashion giving rise to a super tough material. That is, a blend whose elongation at break (600%) was superior to its two major components (90% for PET and 300% for PE). © 1993 John Wiley & Sons, Inc.
Comonomer enhancement effect of 1‐hexene in ethylene copolymerization catalyzed over MgCl2/THF/TiCl4 catalysts
Authors: Kim I. , Kim J. H. , Choi H. K. , Chung M. C. , Woo S. I.
Published: April 2003

Homo‐ and copolymerization of ethylene were performed by using a catalyst system composed of TiCl4/THF/MgCl2 complex activated with AlEt3 at 70°C and 3 atm. To investigate the effect of the compositional difference of the catalyst on the rates of homo‐ and copolymerization and on the reactivity in ethylene–hexene copolymerization, a series of six catalysts with different compositions (Mg/Ti = 0.4–16.5) were prepared by coprecipitation. The catalytic activity in ethylene polymerization increased sharply with the Mg/Ti ratio from 21 (Mg/Ti = 0.4) to 1477 kg PE/g‐Ti h (Mg/Ti = 16.5). The activity in copolymerization with 1‐hexene also increased with Mg/Ti ratio. The values of r1 were 120, regardless of Mg/Ti ratios within the experimental error range. Enhancement of the polymerization rate by the addition of 1‐hexene in the reaction medium was observed only for the catalysts of low Mg/Ti ratio. This unusual effect of 1‐hexene on the polymerization rate was explained by chemical and physical processes that occurred during polymerization. © 1993 John Wiley & Sons, Inc.
The polymerization mechanism and kinetics of DGEBA with BF3‐MEA
Authors: Tackie Michael , Martin George C.
Published: April 2003

The diglycidyl ether of bisphenol‐A (DGEBA) and boron trifluoride monoethylamine (BF3‐MEA) were used in a model system to investigate the chemical and physical changes that occur during polymerization. Experiments using 19F and 1H nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) showed that BF3‐MEA breaks down rapidly into HBF4 and an amine salt at 85°C and above. The HBF4 complexes with the epoxy groups, producing an activated monomer that reacts with epoxy in an etherification reaction. A mechanism is proposed whereby activated epoxy sites (complexes) continuously add epoxy throughout the reaction, but where unactivated epoxies (monomer molecules) are unable to react with each other. The reaction rate and mode (kinetic vs. diffusion control) therefore are strongly influenced by the BF3‐MEA concentration and the reaction temperature. © 1993 John Wiley & Sons, Inc.
Relaxations in thermosets. XXV. Calorimetric studies of the curing kinetics of pure and rubber‐containing epoxy‐based thermosets
Authors: Wasserman S. , Johari G. P.
Published: April 2003

The curing kinetics of diglycidyl ether of bisphenol‐A, with ethylene diamine, propylene diamine, and hexamethylene diamine, with 60 wt % amine‐terminated butadiene acrylonitrile (ATBN) and without, have been measured under both isothermal and ramp‐curing conditions. The phase separation of ATBN is undetectable by calorimetry, but has a significant effect on both the rate of curing and the extent of cure. In all cases, its presence decreases the extent of cure and lowers the Tg of the thermoset formed. The total heat of reaction for the curing is 445 ± 15 J/g and remains unaffected by both the presence of an elastomer and the increase in the molecular size of the curing agent. None of the formalisms available for the curing kinetics of epoxy‐based thermosets is consistent with the results for the neat thermosets. The average activation energy for the reactions increases from 107 to 150 kJ/mol when ethylene diamine is replaced by hexamethylene diamine, but curing reaches near completion in a shorter time with the latter than with the former. The Tg of the latter thermoset is lower than that of the former and follows a decreasing trend with increase in the molecular size of the curing agent—an effect that is related to the increase in the length of cross‐links in the network structure. © 1993 John Wiley & Sons, Inc.
A study on the preparation and performance of polydimethylsiloxane‐coated polyetherimide membranes in pervaporation
Authors: Bai J. , Founda A. E. , Matsuura T. , Hazlett J. D.
Published: April 2003

Separation of acetic acid/water mixtures by pervaporation was attempted by silicone rubbercoated polyetherimide membranes. In particular, the effect of the pore size of the polyetherimide membrane and the condition of silicone rubber coating on the performance of the composite membrane was investigated. It was found that the composite membrane could become either water selective or acetic acid selective, depending on the pore size of the support membrane and the condition of the silicone rubber coating. Thus, the overall performance of the composite membrane can be governed, either by the top coated layer or by the bottom support layer.
Pressure–volume–temperature relationships for polymeric liquids: A review of equations of state and their characteristic parameters for 56 polymers
Authors: Rodgers Patrick A.
Published: April 2003

A review of theoretical equations of state for polymer liquids is presented. Characteristic parameters for six equations of state, as well as parameters for the empirical Tait equation, are given for 56 polymers where pressure–volume–temperature (PVT) data over a wide range of conditions could be found in the literature. New PVT data are presented for four polymers: poly(epichlorohydrin), poly(ϵ‐caprolactone), poly(vinyl chloride), and atactic polypropylene. All six equations of state provide adequate fits of the experimental specific volume data for the 56 polymers in the low pressure range (up to 500 bar). The modified cell model of Dee and Walsh, the Simha–Somcynsky hole theory, the Prigogine cell model, and the semiempirical model of Hartmann and Haque, were all found to provide good fits of polymer liquid PVT data over the full range of experimental pressures. The Flory–Orwoll–Vrij and the Sanchez–Lacombe lattice–fluid equations of state were both significantly less accurate over the wider pressure range. © 1993 John Wiley & Sons, Inc.
Toughening epoxy resins with polyepichlorohydrin
Authors: Jackson Mervyn B. , Edmond Lex N. , Varley Russell J. , Warden Peter G.
Published: April 2003

Polyepichlorohydrin (PECH) rubbers were found to toughen epoxy resins based on the diglycidyl ether of bisphenol A (DGEBA) and cured with piperidine. The degree of toughening depends on the molecular weight of the PECH and on the curing temperature. Best toughening was achieved with PECH of the highest nominal molecular weight of 3400 (Hydrin 10 × 2). Hydrin 10 × 1 (nominal molecular weight 1700) did not toughen the epoxy resin unless bisphenol A was also added, whereas Hydrin 10 × 2 toughened it in the absence of bisphenol A. Curing resins containing bisphenol A and Hydrin 10 × 1 at 160°C resulted in a slightly more brittle resin than when cured at 120°C. The effect of PECH rubbers on the Tg, modulus, and hot/wet properties is similar to that of carboxy‐terminated butadiene‐acrylonitrile rubbers (CTBN). Dynamic mechanical thermal analysis (DMTA) and scanning electron micrographs (SEM) of fractured surfaces show that the PECH separates as a discrete phase during curing. © 1993 John Wiley & Sons, Inc.
Polymerization of 3,9‐dimethyl‐1,5,7,11‐tetraoxaspiro [5,5] undecane with dithiols
Authors: Luo Yanming , Bailey William J.
Published: April 2003

New polymers containing spiroorthocarbonate units on the main chain were synthesized and characterized. The polymers were prepared by using redox or free‐radical catalysts in solution polymerization of 3,9‐dimethylene‐1,5,7,11‐tetraoxaspiro [5,5] undecane [or simply called bimethylenespiroorthocarbonate (BMSOC)] and dithiols at lower temperatures. Their spiroorthocarbonate units could undergo hydrolysis in acidic conditions at room temperature. The structure of polymers was investigated by nuclear magnetic resonance (1H‐ and 13C‐NMR) and Fourier transform infrared (FTIR) spectroscopy. The kind of dithiols had a remarkable effect on properties of the polymers. Block polymers obtained from BMSOC and dithiols could result in a better combination of properties. © 1993 John Wiley & Sons, Inc.
Physical studies of ionically terminated polytetrahydrofuran polymers. IV. Solid‐state studies
Authors: Ali S. A. M. , Hourston D. J.
Published: April 2003

The object of this work was to investigate the effect of the introduction of pyridinium chain‐ends in polytetrahydrofuran (PTHF) polymers on certain solid‐state properties. A comparison of solid‐state properties of methoxy‐terminated (PTHF‐OMe) with pyridinium bromide‐terminated (PTHF‐Py) polytetrahydrofuran polymers of virtually identical molecular weights was made. Crystallization studies and dynamic mechanical and stress‐strain analyses have been undertaken. It was concluded that the introduction of the ionic pyridinium bromide groups to the PTHF polymers influenced the degree of crystallinity and this, in turn, affected other physical properties. © 1993 John Wiley & Sons, Inc.
Radiation degradation of fluoropolymers: Carboxylated fluoropolymers from radiation degradation in presence of air
Authors: Bürger W. , Lunkwitz K. , Pompe G. , Petr A. , Jehnichen D.
Published: April 2003

Irradiation of PTFE by accelerated electrons in the presence of air gives rise to a carboxylated structures at doses above 50 kGy. The surface of the irradiated suspension polymerizate TF 1750 is more carboxylated than is the bulk. The influence of oxygen content and radicals is much higher than it is with the emulsion polymerizate TF 2025. The melting point of irradiated PTFE increases at low doses. Electron‐beam irradiation of the fluorinated copolymers perfluoroalkoxy (PFA) and tetrafluoroethylene‐hexafluoropropylene (FEP) leads to loss of fluorine. In all cases, the oxygen uptake was higher near the surface than in the bulk. PFA was better carboxylated than was FEP. The fact that cross‐linking was not found to a measurable extent up to 800 kGy suggested that double‐bound formation was important. The main effects of electron‐beam irradiation are chain scission, oxidation, and unsaturation depending on dose rate, oxygen content, and particle size. © 1993 John Wiley & Sons, Inc.
Influence of the antimony catalyst remnants on the melt crystallization of PET
Authors: Di Fiore C. , Leone B. , De Rosa C. , Guerra G. , Petraccone V. , Di Dino G. , Bianchi R. , Vosa R.
Published: April 2003

The nucleating activity of antimony catalyst remnants on the melt crystallization of poly(ethylene terephthalate) (PET) is proved through comparisons, for samples with Sb concentrations in the range 180‐1850 ppm, of the crystallization behaviors before and after a complete extraction of the catalyst remnants. These comparisons are performed by analysis of the crystallization peaks of differential scanning calorimetry (DSC), by the study of the isothermal crystallization kinetics from X‐ray diffraction experiments, and by optical microscopy observations of the size of the spherulites. The dependence of the crystallization temperature (Tc, as evaluated by the position of the DSC peak) on the Sb concentration, reported in the literature, is shown to be largely overestimated. In particular, it is found that the Tc of commercial samples are essentially unaffected by the presence of the standard concentrations of Sb catalyst remnants. © 1993 John Wiley & Sons, Inc.
Viscous properties of polymer‐thickened water‐in‐oil emulsions
Authors: Pal Rajinder
Published: April 2003

The viscous flow properties of polymer‐thickened water‐in‐oil emulsions were measured using a coaxial cylinder viscometer. The emulsions were prepared using deionized water and polyisobutylene in oil solutions. Three different molecular weight polyisobutylenes (Vistanex MML‐140, Vistanex MML‐100, and Vistanex MML‐80) were studied. The effects of polymer concentration and water (droplet) concentration on the flow properties were determined. The polymer concentration varied from 0 to 3.96% by weight based on the oil phase whereas the water concentration varied from 0 to 80% by volume (based on total emulsion volume). The polymer solutions behaved like non‐Newtonian Ellis model fluids. At low water concentrations, the flow curves for emulsions were similar to their suspending medium (polymer solution). At high values of water concentration, emulsions clearly exhibited a yield stress. The yield stress increased with both water and polymer concentrations. The shear stress/shear rate data for the emulsions possessing a yield stress were described adequately by a modified Herschel‐Bulkley model. A comparison was also made of the relative viscosities of emulsions having different polymer concentrations. The relative vis‐cosities for polymer‐thickened emulsions were found to be significantly lower than the corresponding values for emulsions without polymer. The correlation of relative viscosity/ concentration data is discussed. © 1993 John Wiley & Sons, Inc.
Fast determination of polymer melt viscosity by optical falling needle viscometer
Authors: Chu Benjamin , Wang Jian , Tuminello William H.
Published: April 2003

An optical falling needle rheometer was employed to measure the melt viscosity of high density polyethylene (HDPE) and low molecular weight poly (tetrafluoroethylene) (PTFE). The temperature dependence of the melt viscosity of these two polymers was obtained and described by an empirical Arrhenius relation. At the present time, this method has been confirmed to be a simple and fast (within several tens of seconds for each measurement) approach to determine polymer melt viscosities of up to at least 1×105 Pa s. The sample cell containing ∼ 2.5 cm3 materials can be vacuum sealed and disposed of without the need of subsequent cleaning each time, which could be a useful feature. In comparison with HDPE, the PTEF sample melt was found to show a much higher melt viscosity with about the same degree of polymerization. © 1993 John Wiley & Sons, Inc.
Transport properties of dichloromethane in glassy polymers. II. Amorphous syndiotactic polystyrene films
Authors: Vittoria V. , Filho A. Ruvolo
Published: April 2003

Sorption and diffusion of dichloromethane vapor were measured in amorphous syndiotactic polystyrene films, obtained with different cooling conditions and after controlled aging times at different temperatures. The diffusional behavior, at the temperature of 25°C, was characterized by three stages, depending on penetrant activity. In the first stage, at low activity, the diffusion coefficient was independent of vapor concentration; the second stage was characterized by concentration‐dependent diffusion, whereas in the third stage, at high activity, the strong interaction solvent–polymer increased the mobility, allowing the polymer crystallization. The different cooling conditions neither have an effect on the diffusional behavior nor on the sorption curve. The aging, both at room temperature and at 70°C, did not change the diffusion parameters, but led to the appearance of more and more anomalous sorption behavior. The sorption curve, as a function of vapor activity, did not show any difference for the fresh and the aged‐at‐room temperature samples, whereas the samples aged at 70°C presented a lower sorption at low activity. The presence of ordered domains, impermeable to the penetrant at low activity, was suggested on the basis of sorption results. The solvent‐induced crystallization was investigated for all the samples. Crystallization was induced at an activity of 0.45 for the fresh and the aged‐at‐room temperature samples; at variance, the samples aged at 70°C crystallize at a slightly higher activity, reaching, nevertheless, a higher level of crystallinity. © 1993 John Wiley & Sons, Inc.
Rate of electropolymerization of N,N'dimethyl acrylamide in aqueous sulfuric acid solution
Authors: Iroh Jude O. , Bell J. P. , Scola D. A.
Published: April 2003

Electropolymerization of N,N‐dimethylacrylamide has been performed in aqueous sulfuric acid solution, using unsized AS‐4 graphite fibers as the working electrode. The electro‐polymerized poly (N,N‐dimethylacrylamide) deposited on the surface of the graphite fiber working electrode. The formation of poly (N,N'dimethyl acrylamide) was inhibited by hydroquinone. The addition of about 0.05 moles of hydroquinone to the reaction solution resulted in about a 90% decrease in the weight gain of fibers, in agreement with the proposed free radical mechanism of aqueous electropolymerization. The rate of electropolymerization varied with the initial monomer concentration, current density, and sulfuric acid concerntration, raised to the power of 1.3, 0.42, and 0.07, respectively, that is, Rp ∝ [M]1.3‐Cd0.42 [H2SO4]0.07. A mathematical model, based upon free radical polymerization kinetics, is discussed. © 1993 John Wiley & Sons, Inc.
Experimental measurement of internal stresses in polypropylene‐injected disks
Authors: Delbarre P. , Jasse B. , Pabiot J. , Rietsch F.
Published: April 2003

Disks in polypropylene were injected in a mold with an unbalanced cooling pattern to induce warpage. The internal stresses were determined using IR dichroism for molecular orientation measurement and an original method for thermal stress assessment, on the basis of the analysis of the dilatometrical behavior of microtomed cuts removed from the part. From both experimental results and structural observations with an optical microscope, a simple model is proposed to describe the warpage due to the effect of unbalanced cooling. A constant deformation was observed and cannot be described by our model, but calculated relative deformations of the part geometry are in good agreement with experimental results. © 1993 John Wiley & Sons, Inc.
The slip‐reducing mechanism in polypropylene‐laminated films studied by FTIR and XPS
Authors: Nishioka T. , Tanaka Y. , Kume K. , Satoh K. , Teramae N. , Gohshi Y.
Published: April 2003

FTIR spectroscopy and X‐ray photoelectron spectroscopy (XPS) were applied to examine the slip‐reducing mechanism of polypropylene‐laminated films. The relationship between the slip and the amount of lubricants was established on the basis of quantitative analysis of lubricants on the cast and laminated polypropylene film surfaces. The results suggested that erucic amide used as a lubricant for the cast film migrated from the film surface into the adhesive layer, probably due to intermolecular interactions (hydrogen bonds) with an isocyanurate‐ether‐polyol used as an adhesive for laminating the films. This enabled us to understand the slip‐reducing mechanism in the laminated films. © 1993 John Wiley & Sons, Inc.
In situ compatibilization of PET/PS blends through reactive copolymers
Authors: Maa Chyn‐Tein , Chang Feng‐Chih
Published: April 2003

Polymer blends of poly(ethylene terephthalate) (PET) and polystyrene (PS) are immiscible and incompatible, which has been well recognized. Styrene–glycidyl methacrylate (SG) copolymer has been synthesized by suspension polymerization and employed in this study as an in situ compatibilizer for the polyblends of PET and PS. This copolymer contains reactive epoxy functional groups that are able to react with PET end groups OH and COOH) under melt conditions to from SG‐graft‐PET copolymer. The presence of a small amount of phosphonium catalyst (200 ppm) accelerated the graft reaction and results in a better compatibilized blend. The compatibilized PET/PS blend has a smaller phase domain and higher viscosity than does the corresponding noncompatibilized blend. Mechanical properties of the compatibilized blends have also been improved significantly over the corresponding noncompatibilized blends. © 1993 John Wiley & Sons, Inc.
Effect of polymerization initiator on early colour of poly(vinyl chloride)
Authors: Rogestedt Mikael , Jonsson Torbjörn , Hjertberg Thomas
Published: April 2003

The development of early colour and the dehydrochlorination rate were compared for poly(vinyl chloride) samples obtained by suspension polymerization using two different initiators, dicetylperoxydicarbonate and butylperoxyneodecanoate. The degree of discolouration was measured on pressed plates and expressed as yellowness index (YI), the polyene sequence distribution was monitored by UV/Vis‐spectroscopy, and the degradation rate was determined by measuring evolved HCI conductometrically. The PVC sample initiated by dicetylperoxydicarbonate exhibited more extensive early colour and a higher dehydrochlorination rate as compared to the sample obtained with butylperoxyneodecanoate as initiator. The UV/Vis‐spectra showed that the early colour originates from polyene sequences. After extraction of the PVC resins with heptane: acetone (85 : 15) the early colour turned out to be almost the same for the two samples. From 13C‐NMR measurements it was found that the extract of the sample polymerized with dicetylperoxydicarbonate contains unreacted initiator. We suggest that the radicals formed when the remaining initiator decomposes initiate dehydrochlorination. Our results also indicate that radicals from dicetylperoxydicarbonate may cause long‐chain branches during polymerization. The radicals formed from butylperoxyneodecanoate, on the other hand, do not seem to react with the polymer molecules. © 1993 John Wiley & Sons, Inc.
Effect of mode of filler addition on the dynamic mechanical properties of epoxidized natural rubber‐cis‐1,4‐polybutadiene rubber blend
Authors: Varughese Susy , Tripathy D. K.
Published: April 2003

The effect of different modes of filler addition on dynamic mechanical properties of 50/50 blends of epoxidized natural rubber (ENR) and cis‐1,4‐polybutadiene rubber (BR) has been studied. The present study is confined to the systems that have fillers alone to reduce complexities due to the presence of other compounding ingredients and vulcanization. The effects of both carbon black and silica filler have been investigated. The mode of filler addition was found to have a profound influence on the loss tangent (tan δ) peak height, its spread, and the storage modulus, E′ value. The tendency of the filler to adhere predominantly to one of the phases depends on the mode of filler addition and the processing history rather than the individual component polarity or viscosity. © 1993 John Wiley & Sons, Inc.
Melting and recrystallization of PA‐6/PA‐66 blends
Authors: Rybnikár̆ Frantis̆ek , Geil P. H.
Published: April 2003

The morphology of a number of polyamides (PA)—namely, PA‐66, PA‐6/PA‐66 blends, and PA‐6/PA‐66 copolymers—prepared from HCOOH solution and from the melt has been examined as well as the effect of annealing. In the blends, the PA‐6 crystallizes within the PA‐66 spherulites. When prepared from HCOOH solution at 25°C, the PA‐66‐containing samples show a large exothermic peak before the sample melting peak is observed by DSC. This exothermic peak, which cannot be fully explained by previously known observations, PA recrystallization, and/or the morphology changes we describe here, is not seen for PA‐6 or for PA‐66 prepared from HCOOH solution at 100°C. © 1993 John Wiley & Sons, Inc.
Effect of graft chain length of the stabilizer on dispersion polymerization of methyl methacrylate in petrol
Authors: Kargupta Kajari , Rai Purnendu , Kumar Anil
Published: April 2003

To carry out dispersion polymerization of methyl methacrylate (MMA) in petrol, we have used a poly(MMA) grafted‐poly(12‐hydroxystearic acid) copolymer as the stabilizer. This special copolymer was prepared as a solution in a mixture of ethyl acetate and butyl acetate solvents. We investigated the effect of graft chain length of the stabilizer on the dispersion polymerization in petrol. We synthesized the stabilizer copolymer with n = 1–4 and determined the rate and the molecular weight of the PMMA formed. There is no dispersion polymerization for n = 1. However, for any other n, for a given stabilizer concentration, as the chain length of the graft is increased, the molecular weight as well as the rate of PMMA formation increases. As opposed to this for a given graft length as the concentration of the stabilizer increases, the molecular weight of PMMA first rises, but for a larger concentration, it begins to fall after undergoing a maximum. In this work, we modeled the heterogeneity of the reaction mass and proposed a mathematical model for dispersion polymerization of MMA in petrol. The computer results are found to conform to the experimentally observed molecular weight of the PMMA. © 1993 John Wiley & Sons, Inc.
Evaluation of light‐scattering detectors for size exclusion chromatography. I. Instrument precision and accuracy
Authors: Jeng L. , Balke S. T. , Mourey T. H. , Wheeler L. , Romeo P.
Published: April 2003

A systematic evaluation of two types of light‐scattering detectors for size exclusion chromatography (SEC) was completed. The two detectors were the low‐angle laser light scattering photometer (LALLS) and the multiangle laser light‐scattering photometer (MALLS). Instrument evaluations were performed at both room (30–40°C) and high (135–145°C) temperatures using the polystyrene standard, NBS 706, at room temperature and the polyethylene standard, SRM 1476, at high temperature. Results of the evaluation showed that when experimental uncertainties were taken into account LALLS and MALLS demonstrated equivalent precision and accuracy for molecular weight determination. The main source of inaccuracy found (particularly for SRM 1476) was the sensitivity difference between the light‐scattering and the concentration (DRI) detectors; i.e., the DRI detector was unable to measure very low concentrations of very high molecular weight material present in SRM 1476, whereas the light‐scattering detectors respond strongly. It was shown that for LALLS the overall weight‐average molecular weight (M̄w) for the whole polymer calculated using an equation that did not require the DRI detector output circumvented this sensitivity problem while assuming that the low angle used was sufficiently close to zero. Use of this equation for MALLS is possible by extrapolating data from all angles used to obtain a light‐scattering chromatogram at zero angle. However, this possibility was not examined here. A particular advantage of MALLS over LALLS is that MALLS can provide the z‐average root mean square radius (commonly referred to here and in other light‐scattering literature as the “radius of gyration”) values from the same data as those used to obtain molecular weight values. Although the radius of gyration values at each retention volume were not as precise as the corresponding weight‐average molecular weights, at room temperature, precision was better than 2% for a significant portion of the chromatogram. © 1993 John Wiley & Sons, Inc.
Study on the polymer latex agglomeration by another polymer latex
Authors: Zhang Liucheng , Liu Yanqiu , Liu Zhiqing
Published: April 2003

In this paper, the agglomeration of polymer latex that was caused by another latex was studied. The basic pattern and the factors affecting the agglomeration have been ascertained. Two agglomerating peaks appeared as the amount of added agglomeration latex increased. The agglomerating mechanism corresponding these two peaks has been proposed. © 1993 John Wiley & Sons, Inc.
New equation for fitting rheological data of bingham materials
Authors: Philippov G. G. , Gorbunov A. I. , Kestelman V. N.
Published: April 2003

In this article we propose a new equation that combines behaviors of Bingham and Williamson pseudoplastic materials. We compare this equation with other ones, and in the Appendix, we consider its theoretical foundation. © 1993 John Wiley & Sons, Inc.
The effect of a diazide as adhesion agent on composite materials consisting of an elastomeric matrix and short polyester fiber
Authors: Ibarra L.
Published: April 2003

This research reports on the effect of a diazide, i.e., 1.4‐carboxybenzenesulfonyl diazide, which had been incorporated onto fiber by a chemical reaction, on the formation of an interphase between the elastomeric SBR matrix and polyester fiber. The existence of the interphase becomes manifest not only in the variation of the mechanical properties, but especially through swelling measurements and dynamic properties. The effect of the new system based on diazide is similar to that obtained from a conventional adhesive system, but presents certain benefits, such as a shorter curing time due to absence of resin, enhanced tensile strength, and the formation of a more flexible interphase, which entails lesser heat generation due to mechanical energy loss. © 1993 John Wiley & Sons, Inc.
Extraction of gold from Au(III) ion containing solution by a reactive fiber
Authors: Lin Weiping , Lu Yun , Zeng Hanmin
Published: April 2003

Metallic gold was extracted directly from a solution containing Au(III) ion by a reactive fiber with the amidoxime group. It is concluded that in the solution containing Au(III), Cu(II), Zn(II), and Cr(III) the reactive fiber presents high selectivity to Au(III). During the adsorption process, the adsorbed Au(III) is partially reduced into spongy metallic gold and the amidoxime group is finally oxidized into the carboxyl group. © 1993 John Wiley & Sons, Inc.
Growth mechanism of transparent and conducting composite films of polyaniline
Authors: Wan Meixiang , Yang Jing
Published: April 2003

Composites of polyaniline (PANI) with various polymeric matrices as substrates were synthesized by means of diffusion–oxidation of aniline swollen polymeric matrices with FeCl3 as oxidizer. The conductivity at room temperature, transmittance at 400–800 nm, stability in air, and morphology of PANI composite films depend on the polymerization time, concentration of FeCl3, and substrate used. A maximum conductivity at room temperature and the highest transmittance at 500–800 nm can be achieved of 10−1 S/cm and 70–80%, respectively. The growth mechanism of PANI composite films has been discussed. © 1993 John Wiley & Sons, Inc.
Numerical simulations of draw resonance in melt spinning of polymer fluids
Authors: Cao Jinan
Published: April 2003

This article deals with numerical simulations of draw resonance of polymer fluids by employing direct difference methods to solving the governing equations in melt spinning. The stability of each difference method was studied by a comparison of the results obtained from simulations with the theoretical solutions or values. The numerical simulation confirms that the critical draw ratio of draw resonance in an isothermal and uniform tension spinning of a Newtonian fluid is between 20 and 21. The cross‐sectional area of a spinline in draw resonance was found to decrease monotonically from a spinneret toward a take‐up bobbin, although the taken‐up filament shows periodical variation. This study has also illustrated the mechanism of draw resonance previously proposed by the author. © 1993 John Wiley & Sons, Inc.
Viscosity–morphology–compatibility relationship of polymer blends
Authors: Chu Line‐Hwa , Guo Shang‐Her , Chiu Wen‐Yen , Tseng Hsieng‐Cheng
Published: April 2003

To investigate the correlation of viscosity–morphology–compatibility of polymer blends, polystyrene, polybutadiene, and styrene/butadiene triblock copolymer were selected as our materials. A capillary rheometer was used to measure the viscosity. All samples were blended by a two‐roll mill, a Brabender, or by the solution casting method. The morphologies of extruded samples from the capillary were observed by SEM. The relation between the viscosity and the composition of the blend changes with shear rate. It was found that the better the compatability between the two phases of the blend the smaller is the disperse phase domain. The viscosity of polyblends is related to the compatability and composition of the two phase in this blend. In the present study, the rheological behavior of polyblends is explained from the viewpoints of morphology and compatability. © 1993 John Wiley & Sons, Inc.
Effect of L(‐)threonine, 5‐hydroxytryptophane, and 5‐hydroxytryptamine on the ceric‐ion‐initiated grafting of methyl acrylate onto cellulose
Authors: Misra B. N. , Mehta I. K. , Rathore Mahendra Paul Singh , Lakhanpal Sunita
Published: April 2003

In order to study the effect of some radio protecting agents (RPA) such as L(‐)threonine, 5‐hydroxytryptophane (5‐HT), and 5‐hydroxytryptamine on ceric‐ion‐initiated grafting onto cellulose, attempts have been made to graft copolymerize methyl acrylate (MA) in aqueous medium in the presence and absence of RPA. Percentage of grafting has been determined as functions of concentration of (i) ceric ion, (ii) H2SO4, (iii) monomer, (iv) RPA, (v) reaction time, and (vi) reaction temperature. Maximum grafting percentage was obtained at [MA] = 5.53 × 10–2mol/L within 180 min at 45°C in the absence of RPA. Grafting reactions were found to be suppressed in the presence of different RPAs. A plausible mechanism is suggested to explain the observed behavior of RPAs in grafting reactions. The graft copolymers have been characterized by IR spectroscopic and thermogravimetric methods. © 1993 John Wiley & Sons, Inc.
High pressure and low temperature conducting properties of organic semiconducting metal‐anthraquinones
Authors: Vijayashree M. N. , Subramanyam S. V. , Samuelson A. G.
Published: April 2003

High pressure and low temperature conducting properties of 1,4‐diamino anthraquinone, with metals such as cobalt, nickel, copper, and silver, and reported. The complexes formed are oxidatively and thermally stable and are insoluble in common organic solvents. They possess interesting conducting properties. All are semiconductors, showing conductivity in the range 1.98 × 10−1 to 1.36 × 10−6 S/cm, depending upon the metal atom present in the complex. Low temperature (300 K to 30 K) and high pressure (up to 6 GPa) conductivity properties of these materials are reported. Copper complexes have been studied in detail, as they show interesting conducting properties. © 1993 John Wiley & Sons, Inc.
Rapid stabilization of acrylic fibers using ammonia: Effect on structure and morphology
Authors: Bhat Gajanan S. , Peebles L. H. , Abhiraman A. S. , Cook F. L.
Published: April 2003

Acrylic fibers were stabilized, for subsequent carbonization, in oxidizing, inert, ammonia and mixed environments and the stabilized fibers were characterized using several techniques to determine the extent of reactions as well as the morphological changes. Ammonia was shown to accelerate stabilization of acrylic precursors that did not contain other effective initiators, such as acid comonomers. Two effects of ammonia—nucleophilic attack in initiating polymerization of nitrile groups and, possibly, the rapid disruption of lateral order in precursor morphology—combine to produce a significant enhancement in the rate of this intermediate step in the formation of carbon fibers. © 1993 John Wiley & Sons, Inc.
Solubility of cellulose III in sodium hydroxide solution
Authors: Laszkiewicz B. , Cuculo J. A.
Published: April 2003

Studies on cellulose III solubility have been conducted in 8.5% NaOH solution with and without the presence of added substances, such as acrylamide, acrylic acid, acrylonitrile, and thiourea. The highest value of cellulose III solubility was obtained as a result of the introduction thiourea and acrylamide in a 5% ratio of NaOH into NaOH solution. Moreover, dissolving conditions proved to be of great importance. Cellulose III introduced into NaOH solution and repeatedly frozen and unfrozen three times dissolved 50% (dissolving with 5% thiourea). The soluble cellulose fraction showed significantly lower molecular mass in comparison with its insoluble fraction. Comparative studies on cellulose crystallinity using the CP / MAS 13C‐NMR method showed a satisfactory compatibility of results with determinations obtained from the X‐ray method. © 1993 John Wiley & Sons, Inc.
Experimental and modeling studies on styrene–butyl methacrylate copolymerization reaction
Authors: Joshi M. V. , Mukesh D.
Published: April 2003

Radical‐induced copolymerization of styrene and butyl methacrylate was studied. The effects of the initiator (benzoyl peroxide) concentration, reaction temperature, and poly(vinyl alcohol) amount on the rate of reaction and final product quality are also measured. Kinetics studies and optical microscopy of the reaction mixture indicate that the reaction exhibits autoacceleration behavior, which could be suppressed by reducing the reaction temperature. 1H‐NMR of the intermediate and final product samples reveals the monomer sequencing. The monomer reactivity ratios at various temperatures are estimated from the experimental data. The reaction is mathematically modeled by a Monte‐Carlo simulation, and the results of this analysis are compared with observed data. © 1993 John Wiley & Sons, Inc.
Separation of alcohol–water mixture by pervaporation through a reinforced polyvinylpyridine membrane
Authors: Uramoto Hiromu , Kawabata Nariyoshi
Published: April 2003

A membrane consisted of cross‐linked poly(4‐vinylpyridine) and reinforced by a nonwoven cloth made of poly(ethylene terephthalate) was prepared by copolymerization of 4‐vinylpyridine with divinylbenzene in the presence of the nonwoven cloth. Pervaporation performance of this polyvinylpyridine membrane was examined at several feed alcohol concentrations and temperatures. The membrane showed water selectivity, and the permselectivity, αW/A, for the alcohol–water mixture was in the order isopropyl > propyl > tert‐butyl > ethyl > methyl. The membrane showed a large permeability, and the pervaporation flux, ϕ, for the ethanol–water mixture was 7–13 kg/h per square meter of the membrane in pervaporation with sweeping of carbon dioxide under atmospheric pressure and at 40°C. The membrane was durable and long lasting for a prolonged‐period, and permselectivity and permeability of the membrane did not fall off even after repeated use for 1000 h. © 1993 John Wiley & Sons, Inc.
Electrokinetic properties of modified polyester fibers
Authors: Teli M. D. , Prasad N. M. , Vyas U. V.
Published: April 2003

Electrokinetic properties of normal polyester flat filament, texturized polyester and cationic dyeable polyester were studied when solutions of different pH and cationic dye concentrations were run through them. The textured polyester exhibited maximum negative zeta potential whereas cationic dyeable polyester showed minimum. The negative zeta potential was found to be maximum near neutral pH. The effect of heat‐setting at extreme conditions (220°C, 90 s) on electrokinetic properties was also studied. Such heat‐setting was found to lower negative zeta potential, attributed to a decrease in surface area. Cationic dyeable, “easy” dyeable, and normal flat filament type polyester were also investigated. Results with respect to negative zeta potential, surface charge density, and surface conductivity, are discussed. © 1993 John Wiley & Sons, Inc.