bluuebunny/crossref_metadata_2025 huggingface dataset:
Equilibrium disperse‐dye sorption by isotactic polypropylene films of varied thermal histories
Authors: Yonetake Koichiro , Masuko Toru , Shimanuki Tomoyuki , Karasawa Mikio
Published: April 2003

Spherulitic polypropylene (PP) films prepared by a melt‐quenched process and then exposed to isothermal annealing treatments at various temperatures ranging from 120°C to 155°C have been dyed at 80°C with C.I. Disperse Yellow 7(Y‐7) or p‐aminoazobenzene. Different PP films as crystallized isothermally in the range of 60°C to 155°C have also been dyed with the same dyes. The equilibrium dye sorption (Mo) obtained for these films increased slightly with an increase in polymer volume crystallinity (Cu). Using fine structural data of these films, the change in Mo were analyzed in terms of the mosaic‐block structural model; e.g., the values of Mo were divided into sorption by the amorphous end region (Me) located between lamella surfaces and sorption by the amorphous side region (Ms) located between crystalline cores parallel to the molecular chain axis. The value of Ms increased with increasing Cv in both cases of the dyeing systems, while the value of Me decreased monotonically in an opposite manner. The amorphous chains in the side region seem to have a strong affinity to a long rodlike dye molecule of Y‐7; this feature is considered to be associated with the extended chain conformation of the side region which originates from distorted lattice chains.
Ionically crosslinked poly(acrylic acid) membranes. IV. Composite reverse osmosis membranes
Authors: Huang R. Y. M. , Gao C. J. , Kim J. J.
Published: April 2003

Composite reverse osmosis membranes of ionically crosslinked poly(acrylic acid) (PAA) have been prepared. The process consists of coating a porous polysulfone membrane with a thin layer of dilute solution of PAA, drying the thin liquid layer, and ionically crosslinking the PAA in solutions of different salts. The influence of some important preparation parameters on the properties of these membranes was investigated. It was found that all these membranes possessed ion exchange properties and could be ion exchanged; some of them have been found to be suitable for the desalination of low concentration salt solutions. By comparison to cellulose acetate (CA) membranes, higher rejection of phenols may be an interesting property of these membranes.
Dynamic mechanical properties of photopolymerizable poly(vinyl alcohol)–acrylate monomer blends
Authors: Koshiba Mitsunobu , Yamaoka Tsuguo , Tsunoda Takahiro
Published: April 2003

Dynamic mechanical properties of photopolymerizable poly(vinyl alcohol) (PVA)–monoacrylate blends were investigated by measuring dynamic shear modulus G′ and loss tangent, tan δ. The dynamic mechanical properties of the blends before being exposed to UV irradiation were governed by the weight percent of the monomers which act as plasticizers. On the other hand, the UV‐irradiated blends seemed to be typical two‐phase materials since they revealed two tan δ maxima whose positions were independent of the monomer content. Those two maxima were assigned to PVA and photopolymerized acrylates with reference to the dynamic mechanical data of PVA and a PVA‐polyacrylamide polyblend. Those dynamic mechanical data suggested that insolubilization of the blend type photopolymers should be caused by a decrease in solubility due to graft polymerization of acrylate monomers onto PVA.
Rigid polar composite supports for use in solid phase synthesis
Authors: Akelah A. , Heffernan J. G. , Kingston S. B. , Sherrington D. C.
Published: April 2003

A number of particulate polyethylene and polypropylene based matrices have been γ ‐radiation grafted with poly(acryloylsarcosine methyl ester). The resulting composite materials have physicochemical properties attractive for use in continuous solid phase synthesis. Three macroporous polystyrene resins have also been impregnated with a secondary polyamide network using thermal initiation. All of these retain their rigid spherical structure and the composite properties again make them good candidates for use under pressure. One of these has been used in a preliminary solid phase experiment and two successive amino acid residues coupled with ∼100% yield.
Chemorheology of thermosetting resins. III. Effect of low‐profile additive on the chemorheology and curing kinetics of unsaturated polyester resin
Authors: Lem Kwok‐Wai , Han Chang Dae
Published: April 2003

An experimental study was conducted to investigate the effect of low‐profile thermoplastic additives on the rheological behavior during cure and the curing kinetics of unsaturated polyester resin. For the study, a general‐purpose polyester resin was used and two different types of thermoplastic additive, poly(vinyl acetate) (PVAc) and poly(methyl methacrylate) (PMMA), were used as low‐profile additives. It has been found that, during cure, the resin/PMMA system exhibits shearthinning behavior even before the cure time reaches the critical value tη∞ whereas the resin/PVAc system does not. Also, both PVAc and PMMA help reduce the shrinkage of the resin during cure. However, our study shows that shrinkage control becomes effective only when the shear rate is greater than a certain critical value. The curing behavior determined with the aid of differential scanning calorimetry (DSC) shows that the rate of cure and the final degree of cure are decreased when the amount of low‐profile additive is increased.
Ionic heterogeneities in sulfonated polysulfone films
Authors: Sivashinsky N. , Tanny G. B.
Published: April 2003

Measurements of glass transition temperature, small‐angle x‐ray scattering (SAXS), and transmission electron microscopy (TEM) have been applied to the study of ionic heterogeneities in sulfonated polysulfone (SPS) films. The SAXS study confirms the existence of heterogeneities in the electron density distribution, whose appearence for the Cs+1, Ca+2, and Fe+3 forms of SPS but not for H+ suggests that the scattering centers are ion‐containing regions. However, a TEM study could not detect the existence of microseparated regions down to a level of 50 Å and the Tg behavior as a function of IEC was more typical of that for random copolymers. A Mössbauer study, performed earlier by Heitner‐Wirguin et al. on samples of our material, indicated the existence of clusters ∼35–40 Å in diameter.
Effect of stabilizer type on the mechanical properties of rigid poly(vinyl chloride). I
Authors: Younan M. Y. A. , El‐Rifai M. A. , Mohsen R. , El‐Hennawi I. M.
Published: April 2003

The effect of stabilizers on the mechanical properties of UPVC and how these are affected by different formulations has been studied. Three stabilizers, tin mercaptide MT, lead system Pb, and Ba/Cd/Zn complex BCZ, were used. A high ‐intensity blender was used for dry blend compounding, and the blend was injection ‐molded on a Kuasy single Screw injection molding machine. A two ‐cavity mold was made for forming the specimens. The specimens were tested for their impact strength, fracture toughness, tensile strength, and flexural strength. Increasing MT stabilizer was shown to increase the tensile strength and to decrease fracture toughness, impact strength, and ductility; this was attributed to antiplasticization. Increasing the Pb stabilizer conferred ductility and improved fracture toughness and impact strength. It is concluded that stabilizers have a marked effect on the mechanical behavior of rigid PVC.
Time‐dependent characteristics of sulfonated EPDM containing zinc stearate. I. Thermal behavior
Authors: Weiss R. A.
Published: April 2003

The crystallization and melting of zinc stearate (ZnSt) in ZnSt‐plasticized compositions of ethylene–propylene–diene terpolymer (EPDM) and sulfonated EPDM (S‐EPDM) have been studied by differential scanning calorimetry. While immiscible in both EPDM and S‐EPDM, ZnSt is compatible with the latter. This compatibility presumably arises from either electrostatic or dipole–dipole interactions between the carboxylate functionality of ZnSt and the sulfonate groups of the polymer. The crystallization behavior of ZnSt is significantly perturbed when the material is added to S‐EPDM, and the crystalline ZnSt phase that results is strongly time dependent. ZnSt first crystallizes as small imperfect crystals when the compositions are cooled from the melt, but it eventually anneals at room temperature into larger, more perfect crystals. Time dependent changes in the mechanical properties of these compositions are also demonstrated and it is suggested that this may be due in part to changes in the ZnSt morphology.
Comparison between a linear and a branched low‐density polyethylene
Authors: Attalla G. , Bertinotti F.
Published: April 2003

Two low‐density polyethylenes, a linear low‐pressure (LLDPE) and a branched high‐pressure (LDPE), have been compared. Their shear and extensional behavior and melt fracture phenomena have been investigated, and some mechanical and optical properties of their blown films have been measured. The rheological analysis showed major differences between the samples, both in shear viscosity and in elongational viscosity. The LLDPE exhibited two types of melt fracture, the first of which—a fine scale extrudate roughness—was not shown by the LDPE and appeared at a very low shear rate. The concomitance in LLDPE of a high shear viscosity and a low elongational viscosity and the presence of melt fracture at low shear rate resulted in its more difficult processing into film. The mechanical properties of the LLDPE film approached those of high‐density polyethylene while the optical characteristics were in the range of LDPE. Such a coexistence of properties makes LLDPE an interesting material for film production.
Radiation crosslinking of poly(vinyl chloride) with trimethylolpropanetrimethacrylate. IV. Effect of diundecyl phthalate: Dependence of physical properties on composition
Authors: Bowmer T. N. , Vroom W. I.
Published: April 2003

Blends of poly(vinyl chloride) (PVC) with polyfunctional monomers may be crosslinked by ionizing radiation. The physical properties of PVC blended with trimethylolpropanetrimethacrylate (TMPTMA) and diundecyl phthalate (DUP) were studied. The TMPTMA monomer crosslinked the blend by homopolymerization and/or grafting to PVC. The plasticizer, DUP, was chemically inert under irradiation but, by plasticizing the macromolecules and diluting the monomer, changed the kinetics extensively. Characteristics of the glass transitions and the tensile mechanical properties have been correlated with blend composition and radiation dose. Before irradiation, poly(vinyl chloride) was plasticized by both DUP and TMPTMA monomer. The increase in glass transition temperature and mechanical strength following irradiation to 5 Mrad was correlated with the TMPTMA content of the blend. Both the molecular structure of the network and the DUP content of the blend were factors in determining the physical properties of the final crosslinked blend. The molecular structure was determined by the kinetics of the crosslinking reactions, which in turn were determined by the blend composition. A molecular interpretation consistent with the physical properties, chemical kinetics, and mechanism of the crosslinking system has been presented.
Effects of low molecular weight aliphatic diols on the polyurethane elastomers prepared from hydroxyl‐terminated polybutadienes
Authors: Idage B. B. , Vernekar S. P. , Ghatge N. D.
Published: April 2003

Hydroxyl‐terminated polybutadienes were prepared by using azo initiators such as di(4‐hydroxybutyl)‐2,2′‐azobisisobutyrate and di(3‐hydroxybutyl)‐2,2′‐azobisisobutyrate, one of which contains primary and the other secondary hydroxyl groups. The effects of aliphatic diols and 2,4‐toluene diisocyanate (TDI) in the presence of dibutyltindilaurate (DBTDL) as catalyst, on crosslinking of primary and secondary hydroxyl groups, were studied. Polyurethane elastomers from these polymers are prepared by using different ratios of diols, 2,4‐toluene diisocyanate and catalyst. Physical properties such as hardness, tensile strength, 100% modulus, and elongation at break of these polymers were studied with a view to compare them with the physical properties of elastomers prepared from ARCO R‐45M.
Properties of filaments spun from poly(ethylene terephthalate) chips containing PET–dust
Authors: Datye Keshav V. , Duraiswamy R.
Published: April 2003

It is observed that the thick portions in a poly(ethylene terephthalate) (PET) filament differ from the rest in their solution viscosity and birefringence, indicating that they are caused by the inhomogeneity of the polymer melt. To identify the cause of the latter, the PET chips are critically examined. It is found that the waferlike tails on the edge of the PET chips and PET–dust have slightly higher viscosity than the chips. The behavior of the chips and the dust during drying and melt spinning are examined to find whether the dust becomes postpolymerized during drying. Such dried PET–dust exhibits substantially different melting behavior than the chips. The filaments spun from the mixture of chips and PET–dust exhibit significantly higher nonuniformity in properties than the filaments spun from the chips only. It is concluded that the PET–dust entering the extruder with the chips can cause thick portions in the filaments.
A combustibility study of the gaseous pyrolysates produced from some high‐performance fabrics
Authors: Day M. , Suprunchuk T. , Wiles D. M.
Published: April 2003

The flammability limits of the gaseous pyrolysates obtained from a series of conventional, flame‐retarded, and high‐performance textile fabrics have been measured, and the results compared. These data have been utilized to develop a fire hazard index associated with the ignitability and combustibility of the gaseous products of thermal degradation as a result of exposure to a high radiative thermal fire load. Generally, it was found that the high‐performance fabrics behaved better than the flame‐retarded fabrics, which themselves were superior to untreated materials.
The viscosity of an unsaturated polyester
Authors: Kaštánek Alois , Zelenka Jiří , Hájek Karel
Published: April 2003

The zero‐shear viscosities of the fractions of an unsaturated polyester were determined by using a rotation viscosimeter with cone‐and‐plate measuring system. The polyester was prepared by the generally known melt condensation of maleic anhydride, phthalic anhydride, ethylene glycol, and cyclohexanol. The viscosity–temperature relationship and the viscosity‐molecular weight relationship are given. The low value of the critical molecular weight as well as rather high value of the inherent friction factor are probably caused by high forces between polar groups of the chains of an unsaturated polyester.
Protective effect of the phenyl group in γ‐irradiated compatible blends of poly(methyl methacrylate) and poly(styrene‐co‐acrylonitrile)
Authors: Nguyen T. Q. , Kausch H. H.
Published: April 2003

The sensitivity to radiation of mixtures of poly(methyl methacrylate) (PMMA) and polystyrene‐co‐acrylonitile) (SAN) was studied over the entire range of composition. Polystyrene‐co‐acrylonitrile, like polystyrene, is highly resistant to ionizing radiation, having a small Gx value for crosslinking (0.077) and an even smaller Gs value for main chain scission (0.055). In contrast, PMMA degrades readily under irradiation (with Gs = 1.2). In γ‐irradiated blends, the behavior of each polymer is largely influenced by the presence of the other component. Gel formation in SAN is impeded by PMMA, as a result of a decrease in Gx, and a concomitant increase in the ratio Gs/Gx. Flexural strength measurements, along with molecular weight determinations by gel permeation chromatography, demonstrated that SAN had a marked protective effect on PMMA by decreasing Gs (chain scission). This protective effect was not observed in earlier experiments with PMMA–PS blends, in spite of its chemical similarity to the system PMMA–SAN. The difference in behavior between PMMA–PS and PMMA–SAN may be explained on the basis of polymer compatibility. PMMA and SAN form a compatible pair, whereas PMMA and PS are incompatible; thus the short range protective effect of the phenyl groups in PS is inhibited.
The effect of phase separation on the structure and permeability of gelatin–dextran films
Authors: Petrak K. L.
Published: April 2003

The effect of polymer–polymer phase separation on the transport properties of gelatin–dextran films has been studied. In the gelatin–dextran–water system, the phase separation and gel formation do not occur due to the presence of a nonsolvent, but depend entirely on the temperature and the total polymer concentration. It has been found that the permeability of polymer blend films to aqueous solutes can be varied not only by changing the volume ratio of the phases, but also by varying the size of the individual domains of the two phases in the films. Under the conditions of restricted demixing (e.g., after gel formation), the course of the phase separation process can be changed by varying the length of time allowed for unrestricted separation. The two most important parameters affecting the result are the total polymer concentration in the casting solution, and the temperature regime. An exponential dependence of the permeation coefficient on the volume fraction of the solvent in the film is shown.
Thiol modification of difunctional castor oil and its utility as room temperature setting elastomeric material
Authors: Mahajan S. S. , Ghatge N. D. , Khisti R. S.
Published: April 2003

Difunctional castor oil has been reacted with thioglycolic acid for the synthesis of castor oil dithioglycolate (CODT). Elastomeric products have been obtained from CODT alone and in combination with liquid polysulfide polymer LP‐33 by oxidative cure with manganese dioxide. Semireinforced (SRF) carbon black has been used as a filler. CODT has also been evaluated as a flexibilizer for liquid epoxy resin (Synpol 200).
Thermoplastic polyurethane elastomers—thermostability in relation to composition
Authors: Masiulanis Bogumila
Published: April 2003

The dependence of thermal stability of poly(ester‐urethane) elastomers on their composition was investigated. For polyurethanes of hard segment content above 3070, hydroquinone di(β‐hy‐droxyethyl) ether (HQEE) is the choice for good thermomechanical stability while the stability of bisphenol‐A‐based polymers is rather poor. The temperature sensitivity of modulus was essential in the range of ‐30‐24OC, while in the range of 24–70°C i t is moderate. The modulus in the low temperature region depends on the nature of polyesterdiol. Its drop with temperature is lower for poly(hexamethy1ene carbonate) glycol (PHC)‐based polyurethanes than poly(ethy1ene‐adipate) glycol (PEAd)‐based ones. In the high temperature region it also depends on the nature and amount of hard segments. The thermal stability of 4,4′‐dicyclohexylmethane diisocyanate (SMD1)‐based polyurethanes is inferior to the one for 4,4′‐diphenylmethanediisocyanate (MD1)‐derived polymers.
Properties of asymmetric polyimide ultrafiltration membranes. I. Pore size and morphology characterization
Authors: Sarbolouki Mohammad N.
Published: April 2003

Properties of asymmetric UF membranes made by solution casting of aromatic polyimides as a function of fabrication conditions are reported. The characteristic properties investigated include: the overall porosity, hydraulic permeability, the equivalent pore size of the skin layer (via a newly developed general diagram), and morphological features shown by the scanning electron microscope. It was found that as casting solution concentration and/or evaporation period was increased, the average pore size decreased while the skin thickness increased. At low casting solution concentrations the membranes were highly porous and the precipitated polymer phase had a granular structure consisting of aggregates of precipitated polymer micelles. While at high concentrations marcrovoid porosity was reduced but the precipitated polymer phase had a spongy structure. The interstitial openings of the granular skin structure of a membrane made from 15% polymer solution with no evaporation as revealed by SEM showed pore size values that were close to those calculated through pore models.
Novel method of preparing Ag–Hg alloy on polyacrylamide films and their structure
Authors: Lee Jiunn Yih , Tanaka Hisashi , Takezoe Hideo , Fukuda Atsuo , Kuze Eiichi , Iwanaga Hiroshi
Published: April 2003

A novel method is proposed of preparing thin Ag–Hg alloy on PAAm film surface at room temperature: The film of interest is formed by holding PAAm aqueous solution with AgNO3 in Hg‐saturated atmosphere. Two kinds of films, one of which is a conductor and the other an insulator, can be selectively formed with pH‐controlled PAAm solution by ammonia. The conducting surface is assigned to the α phase of Ag–Hg alloy by means of X‐ray analysis. Potentiometric titration and IR spectral studies suggest the existence of PAAm–Ag+ complexes. On the basis of their structure and the oxidation and reduction potential of Ag+ and Hg2+, the mechanism of film formation is also discussed.
Very slow crack growth during osmosis in epoxy and in polyester resins
Authors: Sargent J. P. , Ashbee K. H. G.
Published: April 2003

It has been demonstrated that osmotic pressure filled cracks in both epoxy and polyester resins are elastic cracks. Use of classical formulas for elastic cracks has enabled estimates to be made of the time dependence of Young's modulus for both resins. Use of linear elastic fracture mechanics formulas has enabled stress intensity factors to be determined from measurements of crack profiles. Radical crack growth rates are small, in the range 10−12–10−9 ms−1 for hot water tests, and remain constant over a wider range of stress intensity factor, from 0.3 to 0.8 MPa.m1/2. To a first approximation, constant radial growth rate is compatible with a diffusion controlled mechanism. However, analysis of the data indicates an activation energy of ∼50 kcal. Some evidence is presented for concluding that, in polyesters at least, the true nature of crack propagation can be by way of slip/stick.
Synthesis and characterization of phosphorus‐containing polyamides and copolyamides based on 1‐[(dialkoxyphosphinyl) methyl]‐2,4‐and ‐2,6‐diaminobenzenes
Authors: Mikroyannidis John A. , Kourtides Demetrius A.
Published: April 2003

Phosphorus‐containing polyamides and copolyamides were prepared from 1‐[(dialkoxyphosphinyl)methyl]‐2,4 ‐ and ‐2,4‐diaminobenzenes. The polymers were characterized by infrared and proton nuclear magnetic resonance spectroscopy. differential scanning calorimetry, and thermogravimetric analysis. Their thermal properties were compared with those of the corresponding common polyamides. In addition, the fire resistance of some polyamides was evaluated by determining their limiting oxygen index value.
Radiation grafting of methyl methacrylate monomer on natural rubber latex
Authors: Sundardi F. , Kadariah S.
Published: April 2003

A method of radiation grafting of methyl methacrylate (MMA) monomer on natural rubber (NR) latex has been studied. The irradiation dose in radiation emulsion polymerization of MMA monomer was lower compared to the irradiation dose for grafting of MMA monomer on NR latex, in order to obtain the same degree of conversion. This is due to the size of the rubber particles which are quite large and, hence, not sufficient to ensure an ideal emulsion polymerization. The irradiation dose for radiation grafting of MMA monomer on latex was around 300 krad to obtain a 75% degree of conversion. However, this irradiation dose was lower compared to the irradation dose for bulk polymerization of MMA monomer, in order to obtain the same degree of conversion. This is due to the gel effect in the viscous media. Radiation grafting of MMA monomer on NR latex does not influence the pH of the latex, but influences the viscosity significantly. The viscosity of the NR latex increased with an increase in irradiation dose, due to the increase of the total solid content in the latex. The MMA monomer converted to P‐MMA in NR latex was largely grafted on the NR, or at least insoluble in a solvent for P‐MMA, such as acetone or toluene. The hardness of the pure gum vulcanizate with an increase in the degree of grafting or P‐MMA content, but the other physical properties, such as tensile strength, modulus, elongation at break, and thermal stability, were not greatly influenced by the degree of grafting.
Thermodynamics of creep rupture
Authors: Papazian Harold A.
Published: April 2003

An earlier discussion of the entropy contributions to the well‐known Zhurkov relationship for creep rupture is developed from a more rigorous basis. It is demonstrated that well‐behaved Zhurkov materials (which follow his relationship closely) undergo quasistatic rupture (thermodynamically reversible). Other materials show modified Zhurkov behavior and can be described as undergoing nonquasistatic rupture, with an extra entropy term. By considering studies previously carried out in vacuum, this extra entropy has been attributed to surface phenomena.
Curing studies on modified epoxy and unsaturated polyester resins
Authors: Shukla Arvind , Rao R. M. V. G. K.
Published: April 2003

Experimental studies were carried out on the curing behavior of unsaturated polyester and epoxy resins. The latter were modified with three different fillers (CaCO3, CaSiO3, and glass powder) and their curing behaviors studied. Polyesters exhibited faster cure rates than the epoxy resins. The gel time of the epoxy resins decreased with the addition of fillers. Data indicated that the peak exotherm of these thermosetting resins increased when filled with glass powder. The hardness of the curing mass increased with curing time. The use of gel‐hardness number as a quality control parameter has been suggested.
Radiation‐induced graft copolymerization of mixtures of styrene and acrylamide onto cellulose acetate. IV. Studies on some physical properties and structural characterization by means of scanning electron microscopy
Authors: Bhattacharyya S. N. , Maldas D.
Published: April 2003

Binary mixtures of monomers, e.g., styrene and acrylamide in 1:1 methanol:water solution, were grafted onto cellulose acetate film by taking recourse to preirradiation grafting procedure. The surface modification of the films due to grafting was examined by means of scanning electron microscopy. The mechanical properties, e.g., tensile strength elongation at break, and elasticity as well as water vapor permeability of the grafted films, were investigated. In the case of ungrafted films or when acrylamide was grafted to a low extent, the film surfaces were smooth and hence were not modified to any significant extent. But when acrylamide was grafted appreciably, or when styrene was grafted singly or in binary mixture with acrylamide, the surfaces were found to be covered with fibrils. The pattern of the surface modification also changes with the increase of the extent of grafting. The observed properties of the grafted films were explained on the basis of the electron microscopic results.
Synthesis, characterization, and applications of condensate porous polymeric sorbents based on m‐phenylenediamine
Authors: Dave P. J. , Dasare B. D.
Published: April 2003

A few condensate porous polymeric sorbents were synthesized based on m‐phenylenediamine–melamine–formaldehyde polycondensation using suitable porosogenic agents. They were characterized for ion‐exchange capacity, bulk density, solvent uptake, pH–titration curve, and rate of exchange. Their surface characteristics were studied using mercury porosimetry, scanning electron microscopy, and the uptake of fast green FCF dye. A selected sorbent was studied for the uptake of phenol in static and dynamic conditions, and the uptake performance was compared with commercially available porous anion exchanger Amberlite‐IRA 93. Results obtained clearly indicated that modified products have higher pore volume, higher surface area, and good ion‐exchange kinetics as compared to the conventional gel type product.
Blends of poly(ethylene terephthalate) and a polyarylate before and after transesterification
Authors: Kimura Masao , Salee Gideon , Porter Rogers S.
Published: April 2003

Blends of poly(ethylene terephthalate) (PET) and a copolyester of bisphenol A–terephthaloylisophthaloyl (PAr) (2:1:1) have been studied both before and after transesterification. The physical blends exhibit phase separation in their amorphous states: a pure PET phase and a mixed PAr‐rich phase. In spite of this phase separation, PET crystallinity in blends, normalized to PET fraction, surprisingly goes through a maximum at 25% PAr content. The transesterfied copolymers are noncrystallizable and exhibit a single Tg between those of starting polymers, PET and PAr.
Dielectric relaxation in poly(1,4‐phenylene terephthalamide)
Authors: Murthy U. M. S. , Srinivasan Sriraman , Sobhanadri J.
Published: April 2003

The dielectric behavior of poly(1,4‐phenylene terephthalamide) is reported in this paper as a function of frequency (400 Hz–100 kHz), temperature (30–290°C), and the degree of polymerization (134–228). The general behavior of all the samples of different degrees of polymerization is the same except for the occurrence of the peaks at different positions on the frequency and temperature scales. This difference in behavior could be because of the combined effect of the difference in molecular weights and packing of molecules. The data are completely analyzed for the sample with degree of polymerization n = 210. Two distinct processes are observed, one being observed in the entire temperature range, another orginating in the vicinity of glass transition temperature. The former is analyzed in terms of Cole–Cole distribution and the latter is conformed with a nonexponential decay function. Activation energies are calculated from plots of I/T vs. In τ.
Properties of poly(4‐vinylpyridine‐co‐methyl vinyl ketone) membranes for reverse osmosis
Authors: Oikawa Eizo , Igarashi Yusuke
Published: April 2003

The copolymer prepared from 4‐vinylpyridine and methyl vinyl ketone could form a dense and tough membrane which is stronger than cellulose acetate when crosslinked with malonyl dihydrazide (MD) or 2‐phenyl‐4,6‐dihydrazino‐s‐triazine (PDT), showing a fair performance in reverse osmosis for NaCl and CoCl2 feed. The relationship between the content of MD or PDT and the membrane performance was investigated. An increase in MD or PDT led to an increase in membrane thickness and water content as well as the performance. A maximum rejection was obtained at ca. 30 mol % MD and ca. 13 mol % PDT based on MVK, and a maximum membrane strength at 20–30 mol % crosslinking agent. A membrane of a lower NaCl rejection tended to be permselective due to the complexation of the CoCl2 with membrane. About 1:1 copolymer gave membranes of a higher rejection, which may be related to monomer arrangement in the copolymer chain. There methods for the flux improvement were presented and discussed: preparation of a copolymer blend membrane containing a hydrophilic monomer, crosslinking quaternization of membranes with diiodobutane, and oximation of the membrane material in order to introduce hydrophilic groups.
Enhancement of adhesion between filler and polymer in alumina‐filled rigid polyurethane foams
Authors: Borsus J. M. , Merckaert P. , Jérôme R. , Teyssié Ph.
Published: April 2003

The balance of the reinforcement and flame retardancy of rigid polyurethane foams (PUR) may be envisaged by controlling the dispersion and adhesion of the filler. Encouraging results are reported by grafting onto the filler surface a polymer miscible and reactive with the foam‐forming ingredients. It appears that polyethers may do for PUR foams what the silanes do for glass fiber reinforced plastics.
Flocculation of metal‐bearing waste waters using cellulose and its graft copolymers
Authors: Graczyk T. , Hornof V.
Published: April 2003

Several types of cellulose (wood pulp) and their graft copolymers with water‐soluble monomers were tested for their activity as flocculation aids. They were employed as additives to lime in flocculation experiments involving a simulated mine water containing iron, zinc, and copper salts. The results show that all the cellulosic products had a beneficial effect on the removal of iron, and to a lesser extent on the removal of zinc. The final concentration of ferric ions after 30 min was comparable with that produced by commercial flocculants (Magnifloc, Aquafloc). No improvement of flocculation activity was obtained upon grafting various polar monomers and their mixtures onto dissolving pulp.
Physical and chemical interaction mechanisms in silicone rubbers
Authors: Štefcová P. , Schätz M.
Published: April 2003

Silicone rubbers were prepared with graded concentrations of two different fillers—conventional silica capable of both physical and chemical interactions with the methyl vinyl siloxane polymer and magnetic ferrite powder capable of physical interaction only. The mechanical properties of the experimental rubbers (containing both these fillers at the same time) gave characteristic plots of property isolines in the two filler concentration coordinates. To obtain theoretical counterparts of these plots, physical considerations were used to define the polymer–filler contact surface area in real polymer–filler systems and to derive probable variants of its filler concentration dependence. A mathematical model of the polymer–filler interaction was developed and was explored by computing a series of model diagrams. Comparison of the experimental and computed plots indicated that, even with a chemically active filler present, physical interaction mechanisms are dominant; their contribution in determining the mechanical properties of filled silicone rubbers appears to exceed 93%.
Optimization of nylon 6 reactors with end‐point constraints
Authors: Gupta Santosh K. , Damania B. S. , Kumar Anil
Published: April 2003

Optimal temperature profiles for nylon 6 polymerization in plug–flow reactors have been obtained with end‐point constraints involving the degree of polymerization and the cyclic dimer concentration, using the most recent kinetic information. Computations suggest that the temperature at the feed end of the reactor must be maintained close to the highest permissible level (determined by the boiling point of the ϵ‐caprolactam). The temperatures in this region control the degree of polymerization more than other variables. Thereafter, the temperature should be reduced. This second zone controls the undesirable cyclic dimer concentration. The effect of a systematic change of values of the various design variables is studied. The profiles obtained herein are qualitatively similar to those obtained by earlier workers using similar formulations. However, they differ significantly from the profiles obtained by us earlier, using different objective functions which are more relevant to the design of new reactors. Attempts have also been made to obtain a global optimal scheme to produce polymer of a desired degree of polymerization and cyclic dimer content, using as short a reactor as possible, and using the water content and the modifier concentration in the feed as the independent variables.
Properties of cast urethane elastomers prepared from poly(ϵ‐caprolactone)s
Authors: Balas Adolf , Pałka Grzegorz , Foks Janina , Janik Helena
Published: April 2003

General information on the methods of lactone polymerization has been given. The method applied in this study for obtaining poly(ϵ‐caprolactone) with the use of sodium derivatives of ethanediol, diethylene glycol, 1,5‐pentanediol, and 1,10‐decanediol has been discussed, and the results of the experiments have been given. The properties of cast urethane elastomers prepared from the obtained poly(ϵ‐caprolactone) have also been presented.
Studies of selective adsorption resins. XVIII. The influence of porosity of macroreticular chelating resin on adsorption of heavy metal ions in an aqueous solution
Authors: Maeda Hironori , Egawa Hiroaki
Published: April 2003

In order to choose the most practical macroreticular chelating resins for the removal and recovery of heavy metal ion from industrial waste solution, the influence of the porosity of macroreticular chelating resins on the adsorption for metal ion was studied. The four macroreticular chelating resins (RST) containing triethylenetetramine side chain with different porosity were used. It was found that the adsorption of zinc ion at its low concentration solution was affected by the porosity of the RST. Among the four resins with average pore radius of 21.0, 24.5, 28.0, and 66.5 nm, a resin with that of 66.5 nm gave the highest initial adsorption rate and the largest breakthrough capacity for zinc ion at a space velocity of 15 h−1.
Swelling of cotton fibers in ethylenediamine–morpholine mixtures
Authors: Lokhande H. T. , Sirmour S. G. , Shukla S. R. , Sinha S. B. , Patil N. B. , Chidambareswaran P. K.
Published: April 2003

Cotton fibers were treated with anhydrous mixtures of ethylenediamine and morpholine of varying proportions to study the changes in accessibility (X‐ray crystallinity index, swelling by propanol‐2 retention, formylaiton, and dyeability) as well as lattice conversions from cellulose I to cellulose II and cellulose III. Positive synergistic influence of the highest order was noticed at 70:30 (molar proportion 3:1) ethylenediamine–morpholine mixture as judged from accessibility and lattice conversion from cellulose I to cellulose II. The same critical proportion was found to give the highest order of negative synergistic effect in the lattice conversion of cellulose I into cellulose III. These opposing trends have been explained on the basis of the different mechanisms associated with the lattice conversions of cellulose I into cellulose II and cellulose III.
Reprocessing and shear modification of polyethylene
Authors: Ram Arie , Getz Shimon
Published: April 2003

Reprocessing of used polyethylene serves as a promising solution to a severe ecological and economical problem. This material, however, has frequently been exposed outdoors and demonstrates poor workability and inferior mechanical properties. In this study, we attempt to explore ways for the improvement of flow and product performance by intensive shear processing. When shearing reclaimed polyethylene (LDPE) containing some degree of crosslinking and oxidation, either by repetitive injection molding, extrusion or roll milling, the fluidity of the recycled polymer is gradually increased, frequently with rising ductility of the product and a decrease in melt elasticity. As a result, a practical way of reclaiming poor‐flowing, partially gelled polymer has been found. Additionally, the recycled material can be blended with virgin polyethylene, preferably of the linear low density type. Virgin polyethylene by itself, however, demonstrated an opposite response to intensive shear. There was a drop in fluidity, a rise in melt elasticity, and usually a decrease in ductility. All this is believed to result from the degradation processes that may consist of initiation of microgels and recombination of polymer chains by free radicals, as shown by an actual increase in intrinsic viscosity and in the higher modes of molecular weight averages. It was noted that the controlling mechanism of shear modification of virgin polymer differs from that occurring with a partially crosslinked structure. Results of the shear modification of both virgin and reclaimed polyethylene, by continuous kneading in a Brabender Plastograph, indicate mainly a chain scission mechanism. In all cases the melt viscosity dropped together with the ductility of the final product.
Graft polymerization of propylene sulfide on crosslinked polystyrene
Authors: Domb Abraham , Avny Yair
Published: April 2003

Sulfur containing graft polymers that may be of interest as polymeric transfer agents were synthesized. Graft polymerization of propylene sulfide on crosslinked polystyrene beads was investigated; both crosslinked polystyrene and its chloromethylated derivative were grafted. Crosslinked polystyrene was metallated by BuLi–TMEDA and was used to initiate anionic graft polymerization of propylene sulfide. Graft polymers of high polypropylene sulfide content corresponding to 10 mmol s/g were obtained. The grafted polypropylene sulfide was evenly distributed across the bead cross section. No change in bead surface characteristics was observed. Grafting on chloromethylated polystyrene beads was achieved by reaction between the chloromethylene groups with sulfide groups of performed polypropylene sulfide, and with terminal sodium thiolate groups of living polypropylene sulfide.
Kinetics of phase separation in segmented polyurethanes
Authors: Chee K. K. , Farris R. J.
Published: April 2003

The phase‐separation process in segmented copolymers is treated by first‐order kinetics which couples with the Fox equation to derive an expression for describing the change of soft segment Tg with the annealing time. Kinetic data of five commercial polyurethanes have been analyzed. The studies conclude that the phase‐segregation mechanisms involve two elementary steps which can be characterized by two discrete relaxation times. It has been shown quantitatively that a polyether‐based polyurethane (ET) recovers its original domain structure faster than a polyester soft‐segment material. The average activation energy of the demixing process of an ET polyurethane is found to be about 23 kJ.mol−1 and is not influenced by hydrogen bonding.
Effect of hollow core on the rigidity of fine fibers
Authors: Gupta Dinesh K. , Broughton Roy M.
Published: April 2003

The principles of torsional and transverse vibrations have been utilized to measure the torsional and bending rigidities of fibers, respectively. A simple device, based on the principle of the torsional pendulum, has been designed to test regular and hollow staple fibers of fine denier. A vibroscope (interfaced with an oscilloscope) was used to measure the linear density of the fibers, and the results were used to calculate their torsional and bending rigidity properties. The effect of hollow core on the torsional and bending rigidities of the fibers is reported.
Polymerization of hexamethyldisiloxane by plasma on activated charcoal: Investigation of parameters
Authors: Akovali G. , Hasirci N.
Published: April 2003

The polymerization of hexamethyldisiloxane by plasma (glow discharge) on activated charcoal was investigated. The effects of discharge power, discharge duration, and monomer flow rate on polymer deposition were examined. Maximum deposition was observed when the applied power, monomer flow rate, and discharge duration were 20 W, 50 cm3/min, and 1 h, respectively. The deposited film was investigated by IR, SEM, and ESCA. The same tests were also carried out for plasma‐induced polymer deposits.
Radiation‐grafted polymers for biomaterial applications. I. 2‐hydroxyethyl methacrylate: Ethyl methacrylate grafting onto low density polyethylene films
Authors: Cohn Daniel , Hoffman Allan S. , Ratner Buddy D.
Published: April 2003

Studies were conducted on the radiation grafting of 2‐hydroxyethyl methacrylate (HEMA) and ethyl methacrylate (EMA) by the mutual irradiation technique onto low density polyethylene. Four different solution concentrations were used, and radiation doses ranged from 0.03 to 0.05 Mrad. Four copolymer compositions having different HEMA:EMA ratios were also studied using two total monomer concentrations. The kinetics of the grafting process demonstrated by the two monomers were basically different. While EMA showed a typical diffusion‐controlled kinetic pattern, HEMA exhibited a more complex behavior, the main features of which were an induction period, a slight autoacceleration and a significant drop in graft level after a maximum is reached. The difference in behavior was interpreted in terms of partitioning of monomers into the polyethylene substrate. The surface topography of the grafted films was studied by means of scanning electron microscopy. A mechanism based on osmotic cell formation was suggested for the HEMA graft system. The copolymer systems investigated showed that the graft reaction is faster in the initial stages for higher percentages of EMA in the monomer mixtures; as grafting proceeds the trend is reversed.
Control of ionic interactions in sulfonated polystyrene ionomers by the use of alkyl‐substituted ammonium counterions
Authors: Weiss R. A. , Agarwal P. K. , Lundberg R. D.
Published: April 2003

Polystyrenes containing up to about 20 mol % sulfonic acid are reproducibly and readily prepared by the sulfonation of polystyrene at 50°C with acetyl sulfate in 1,2‐dichloroethane solution. The metal salts of sulfonated polystyrene possess extremely high melt viscosities and are soluble in single solvents such as toluene and THF only at very low sulfonate levels. Such properties are the result of the very strong ion‐dipole interactions among the metal sulfonate groups. Such strong interactions can be substantially reduced through the neutralization of the sulfonic acid with ammonia and, most especially, relatively simple low molecular weight amines. Sulfonated polystyrenes varying in sulfonic acid content from about 1 mol % to about 20 mol % were neutralized with various mono‐, di‐, and tri‐substituted alkyl amines ranging in alkyl chain length from H (ammonia) to C20, and their rheological and thermal properties were measured. As the number of substituents on the nitrogen increased, the glass transition temperature and the melt viscosity decreased. The tributylamine sulfonates possessed viscosities almost as low as unsulfonated polystyrene and the longer chain amines behaved as if internally plasticized. The properties of amine neutralized sulfonated polystyrenes are concluded to be primarily a function of amine size. Increasing the size of the amine reduces the strength of the ion‐dipole interaction by preventing close approach of the amine sulfonate groups.
Raman spectroscopy of urea–formaldehyde resins and model compounds
Authors: Hill Charles G. , Hedren Alicia M. , Myers George E. , Koutsky James A
Published: April 2003

Laser Raman spectroscopy was used to analyze the structures of urea–formaldehyde resins. Band assignments were made on the basis of Raman studies of model compounds. Methylol and certain methylene functionalities could be differentiated in both the model compounds and the resins. Spectra of the resins at various stages of cure were also examined. Trends noted agreed with earlier studies on the kinetics and the proposed mechanism of the cure process. Laser Raman spectroscopy offers promise for elucidating the structures of urea–formaldehyde resins and for providing insight into the molecular phenomena of the cure and degradation of these resins.
Factors affecting the durability of Ca‐complexed methylmethacrylate copolymer films containing CaO–SiO2–H2O macromolecules
Authors: Sugama T. , Kukacka L. E. , Carciello N. , Warren J. B.
Published: April 2003

A CaO–SiO2–H2O macromolecular–ionomer complex was found to be formed in the superficial layers of MMA–TMPTMA copolymer composite films made with filler containing hydraulic cement during exposure in an autoclave at temperatures up to 200°C. This complex acted to prevent the hydrothermal deterioration of the original composite films, which is important if the films are used as protective layers on metals. This complex also contributed significantly to hydrophobicity, a low energy surface, and less surface roughness, thereby lowering the intrinsic water permeability of the films. The glass transition temperature Tg and the tensile strength of the complexed films increased with increasing concentration of the cement additive used as a source of Ca2+ metallic ions, but they decreased when the cement concentration became excessive because of the chain enlargement caused by the growth of a large quantity of hydrated macromolecules. Ca2− ions were found to migrate from the cement grains in an aqueous medium and to have a crosslinking function connecting the oxidized metal surfaces and the functional carboxylate groups located in the pendent parts of the polymer molecules. The resultant shear bond strength of metal‐to‐metal lap joint specimens after exposure for 3 days to water at 150°C was twice as high as that for the samples made without cement.