bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthetic resins: II: Preparation and characterization of resins prepared from aminoacetophenone
Authors: Patra Santosini , Lenka Subasini , Nayak Padma L. 
Published: April 2003

AbstractA number of resins were prepared by condensing m‐aminoacetophenone with substituted aromatic compounds and formaldehyde in the presence of acids and bases as catalyst. The resins were characterized by infrared spectra. The solubility parameters were calculated from Small's group contribution which agreed well with the experimental value. The bacteriocidal properties of the resins have been studied.
Beta dielectric dispersion in natural rubber latex
Authors: Laogun Abimbola A. 
Published: April 2003

AbstractThe dielectric dispersion of natural rubber latex has been investigated over a frequency range of 0.1–100 MHz and at six temperatures from 20° to 70°C. A computer analysis of the dispersion data showed that the Cole–Cole structural equation gave a better fit than the Debye. The large values of the Cole‐Cole α spread parameter suggest heterogeneity of structure in rubber latex. The latex viscosity and the relaxation time were both found to be influenced by changes in temperature. Application of the Arrhenius temperature equation to the data yielded a mean activation enthalpy of 32.6 ± 2.8 kJ/mol for the relaxation process.
Reactivity of epoxy resin in dispersed dicyandiamide system and dynamic viscoelasticity of the resulting product
Authors: Muroi Souichi , Ishimura Hidekazu , Outsuka Masahiko 
Published: April 2003

AbstractA study was made on the curing reaction, leading to a cross‐linked network, of bisphenol A diglycidyl either in a dispersed dicyandiamide (DICY) system containing benzyl dimethylamine accelerator and on the dynamic viscoelasticity of the resulting product as related to the DICY particle size (Ds), and compared with a dissolved DICY system. The curing reaction rate varied inversely with logarithmic Ds and directly with the total surface area of the DICY particles, and the finally attainable extent of reaction of the epoxide group decreased with increasing Ds. Activation energy ranged from 14 to 17 kcal/mole depending slightly on Ds. The dynamic viscoelasticity of the cured product was also affected greatly by Ds. Cured product from the system with a 3 μm DICY displayed only a primary transition peak around 180°C in plots of viscoelastic decrement as a function of temperature. With DICY of larger than 10 μm Ds, the number of transition peaks increased to two or three, with a primary peak, a secondary peak around 140μC, and a tertiary peak around 90μC. The relative height of the secondary or tertiary peak increased with increasing Ds. The reaction of the dissolved DICY system proceeded at much the same rate as the 25 μm Ds system, but yielded a cured product with viscoelasticity similar to that of the 3 μm Ds system.
Thermosensitive dielectric properties in polyamide–phenol hybrid compounds and their application to the temperature‐sensing wire
Authors: Kishimoto Yoshio , Hosaka Tomiharu , Shimotsuma Wataru 
Published: April 2003

AbstractThermosensitive dielectric properteis in polyamide–phenol hybrid compounds have been studied. The polyamide–phenol hybrid compounds are constituted of p‐hydroxybenzoate–formaldehyde condensation oligomer dispersed molecularly in nylon 12 and polyamide copolymer. These materials are less hygroscopic than nylon 12 which is the least hygroscopic among polyamide homopolymers. It will be because the phenol group coordinates to amide group as the less hygroscopic “pseudo‐water” instead of water. One of these materials has also shown an intrinsic hydrophobic effect of hydrogen bond segment due to the “hybrid effect” between polyamide and phenol. The thermosensitive dielectric properties are based on the temperature dependence of intermolecular hydrogen bond behaviors by amide and phenol groups, which have been discussed in relation with the molecular behaviors. The relationship with polarizations constituting dielectric constant and hydrogen bonding molecular segments, and ac hopping conduction behaviors by proton carriers have also been discussed. These materials are applied as a temperature‐sensing material in a flexible thermosensing heater wire, which has three functions, that is, thermosensing, heating, and fusing for safe in the case of an abnormal overheat. As the features for a sensing material, these materials show the humidity low‐dependence and highly thermal stability, and will be situated as one of the high‐performance sensing material useful for the electric warmer such as an electric blanket.
Chain extenders for polyester. II. Reactivities of carboxyl‐addition‐type chain extenders; bis cyclic‐imino‐ethers
Authors: Inata Hiroo , Matsumura Shunichi 
Published: April 2003

AbstractThe reaction behavior of such bis cyclic‐imino‐ethers as 2, 2′‐bis(2‐oxazoline), which had been proved in the previous paper to be an effective chain extender to couple carboxyl terminals of linear polyesters through addition reaction, has been studied to evaluate their practical applicability as the chain extenders for poly(ethylene terephthalate) and poly(butylene terephthalate). It has been observed that a wide range of excess use of 2,2′‐bis(2‐oxazoline) resulted in polyesters of almost similar molecular weight. In addition, when excess amounts of the chain extender were added and the reaction conditions were fixed, the ratio of the coupled carboxyl terminals to the initial carboxyl terminals became constant regardless of the initial molecular weight and carboxyl content (CV). The results indicate that the chain‐extended polyesters possess predetermined molecular weight and CV, both of which depend only on the molecular weight and CV of the initial polymers, and not on the amount of the chain extender added.
Effect of temperature of motionless air on the cure of vulcanizates after removal from the mold
Authors: Khouider A. , Vergnaud J. M. 
Published: April 2003

AbstractThis paper determines the increase in the state of cure through the rubber mass during the cooling period after the vulcanizate is removed from the mold. The problem is complicated because of the great number of parameters. Some of them, such as the dimension of sample, the state of cure through the rubber at the time of its removal from the mold, the nature of the fluid, its agitation and temperature, are of interest. This work is concerned with the study of the effect of the temperature of motionless air in which the vulcanizate is cooled. This parameter is important in increasing the state of cure. Although the problem is complicated, it has been resolved by using a model based on a numerical method of calculation with finite differences. This model takes into account not only heat transfer by conduction through the rubber and by convection through rubber‐air interface, but also the kinetics for heat evolved in the cure reaction.
Polymerization of olefins through heterogeneous catalysis—V. Gas‐liquid mass transfer limitations in liquid slurry reactors
Authors: Floyd S. , Hutchinson R. A. , Ray W. H. 
Published: April 2003

AbstractMany processes for polymerization of olefins employ laboratory, pilot plant, or full‐scale liquid‐phase polymerization reactors with monomer introduced as a gas. Criteria for the presence of gas‐liquid mass transfer resistance in these systems are determined in terms of observed reaction rate or loading of a heterogeneous catalyst of given intrinsic activity. The effects of variables such as reactor size and configuration, temperature, and soluble polymer are also examined. The equilibrium monomer concentrations of ethylene in hexane and propylene in heptane are calculated through a modified Benedict‐Webb‐Rubin equation, and some calculations for ethylene‐propylene mixtures are tabulated. The general methodology for predicting gas‐liquid mass transfer resistance is readily extendible to copolymerization systems.
Blends containing polymers of epichlorohydrin and ethylene oxide. Part I: Polymethacrylates
Authors: Fernandes A. C. , Barlow J. W. , Paul D. R. 
Published: April 2003

AbstractThe phase behavior of blends of various polymethacrylates with poly(epichlorohydrin) (PECH); poly(ethylene oxide) (PEO); and a copolymer of epichlorohydrin and ethylene oxide [P(ECH/EO)], was examined using differential scanning calorimetery (DSC), dynamic mechanical properties, and optical indications of phase separation on heating, namely lower critical solution temperature (LCST) behavior. Poly(methyl methacrylate) (PMMA), was shown to be miscible with PECH, PEO, and P(ECH/EO), while only PECH was found miscible with the higher polymethacrylates: poly(ethyl methacrylate), poly(n‐propyl methacrylate), poly(n‐butyl methacrylate), and poly(cyclohexyl methacrylate). However, even PECH was found to be only partially miscible with poly(isopropyl methacrylate). In many cases, unusually broad glass transitions were observed by DSC for blends which are believed to be the result of equilibrium composition fluctuations. All mixtures showed LCST behavior and based on this and excess volume measurements, to the extent possible, qualitative conclusions were made concerning the relative strength of the interactions among the various blend pairs. For PECH, it appears that the interaction with polymethacrylates decreases with increasing size of the alkyl pendant group, with poly(cyclohexyl methacrylate) being a possible exception. The interaction with PMMA is apparently about the same for PECH and PEO, but somewhat less for P(ECH/EO). The latter is consistent with an intrachain attraction of ECH and EO believed to exist. The reasons for similar interactions of PEO and PECH with PMMA are not understood; however, it is clear that the chlorine moiety of PECH is needed for miscibility with higher polymethacrylates.
Estimation on thermal conductivities of filled polymers
Authors: Agari Y. , Uno T. 
Published: April 2003

AbstractA new thermal conduction model is proposed for filled polymer with particles, and predicted values by the new model are compared with experimental data. The model is fundamentally based on a generalization of parallel and series conduction models of composite, and further modified in taking into account that a random dispersion system is isotropic in thermal conduction. The following equation is derived from the new model; log λ = V · C2 · log λ2 + (1 − V) · log(C1 · λ1). Therefore, when thermal conductivities of polymer and particles (λ1, λ2) are known, thermal conductivity of the filled polymer (λ) can be estimated by the equation, with any volume content of particles (V). The new model was proved by experimental data for filled polyethylene, polystyrene and polyamide with graphite, copper, or Al2O3.
Drop sizes in turbulent liquid–liquid dispersions containing polymeric suspension stabilizers. I. The breakage mechanism
Authors: Borwankar R. P. , Chung S. I. , Wasan D. T. 
Published: April 2003

AbstractPolymeric suspension stabilizers, when used in sufficient quantities, can stabilize liquid–liquid dispersions against coalescence. Experiments were performed using an in situ photomicrographic technique to determine the critical surface coverage of a hydroxypropyl methylcellulose product. The critical surface coverage was between 2.35 × 10−7 and 1.2 × 10−6 g/cm2. Noncoalescing dispersions can be prepared by using high concentrations of suspending agents so that the surface coverage is above the critical value. Such noncoalescing dispersions can be used to study the breakage mechanism even at high dispersed phase volume fractions. The study of the breakage mechanism reveals that the volume swept by the turbine impeller is applicable in calculating the power input per unit mass. The new correlation between the Sauter mean diameter and the extent of agitation under turbulent conditions that is found here is in fair agreement with those available in literature.
Role of polyacrylate starch copolymer in water sorption
Authors: Ziderman I. Irving , Belayche Janine 
Published: April 2003

AbstractWater sorbence by saponified polyacrylonitrile‐grafted polysaccharides was studied in relation to practical end uses. Graft copolymers prepared from wheat flour, corn flour, cotton wool, and rayon fibers swelled to a gel, exhibiting a 10‐ to 20‐fold increase in sorbency over the starting materials. A further enhanced water capacity was obtained when homopolymer was not removed. Soaking the wheat flour copolymer in salts or dilute mineral acid nullified the enhanced water sorbence, which could be reversible restored by neutralization of acrylic acid functions with alkali. Swelling the copolymer in aqueous D‐glucose did not impair its water capacity. The mechanism of swelling to a gel appears to involve electrolyte osmotic pressure generated by a Donnan equilibrium. Grafting starch elevated its heat of water vaporization above that of pure water, and increased its capacity to absorb water from ethanol‐water vapor at 40° above that of native starch. At higher temperatures, however, the dehydrating capacity decreased to that of native flour.
Shear rheology of diluted solutions of high molecular weight cellulose
Authors: Navard P. , Haudin J. M. , Quenin I. , Peguy A. 
Published: April 2003

AbstractA steady‐state and dynamical rheological study was performed with dilute solutions (1–4%) of high molecular weight cellulose (Mw = 350,000). The solutions are strongly viscoelastic. The steady‐state viscosity and the first normal stress difference have a power law dependence on the shear rate. The power law indices have the same dependence on temperature and concentration. These results as well as the correlation between the steady‐state viscosity and the real part of the complex viscosity are in good agreement with the Spriggs model. The 4% concentrated solution shows the beginning of a rubber‐like storage modulus plateau, suggesting the existence of an entanglement network.
The effect of electrolytes on direct dyes for cotton
Authors: Noah A. O. , Martins C. M. O. A. , Braimah J. A. 
Published: April 2003

AbstractElectrolytes generally promote dyebath exhaustion when direct dyes are used for cellulosic fibers, but the extent with which they do so usually varies from one electrolyte to another. Two direct dyes with varying numbers of sulfonic acid groups were investigated. Cotton cellulose was dyed with these dyes using different electrolytes and a phosphate buffer system. The relationship between strength loss with increase in number of sulfonic acid groups was an obvious observation. Wash fastness results had indicated that the most important consideration is the molecular weight and the overall molecular architecture of the dye.
Studies on the reactions between thiocarbamyl sulfenamide and 2‐(iminodithio)benzothiazole accelerator system in the early stage of vulcanization of NR
Authors: Datta Rabindra Nath , Das Prasanta Kumar , Basu Dipak Kumar 
Published: April 2003

AbstractInvestigations on the interactions of the synergistic pair of accelerators comprising of thiocarbamyl sulfenamide and 2‐(iminodithio)benzothiazole have been carried out through hplc. N‐cyclopentamethylene thiocarbamyl‐N'‐oxydiethylene sulfenamide, N‐oxydiethylenethiocarbamyl‐N'‐cyclopentamethylene sulfenamide (OTCS), 2‐morpholinodithiobenzothiazole, and 2‐piperidinodithiobenzothiazole (PDB) have been selected as the reactants which, when suitably combined, provide most effective accelerator systems capable of generating heat and age resistant vulcanizates. The OTCS–PDB system has been found to yield vulcanizates which exhibit the greatest crosslink density, scorch safety, and highest modulus and tensile strength. An attempt has been made to explain the higher activity of the binary systems studied as compared to that obtained from comparable thiocarbamyl sulfenamide plus dibenzothiazyl disulfide system. Zin–dithiocarbamates have been found to influence the curing reactions depending upon the composition of the mixed accelerators. Cyclohexyl thiophthalimide, a versatile cure retarder, reacts with the accelerators to yield cyclohexyl thiomorpholine and cyclohexyl thiopiperidine, as the case may, which also have a profound effect upon cure retardation as noticed in the present investigation.
Copolymer analysis by UV spectroscopy
Authors: Ramelow Ulku , Baysal Bahattin M. 
Published: April 2003

AbstractAn extensive and detailed analysis of copolymers was made by developing a rapid spectrophotometric method. Successful analysis of composition in styrene‐p‐methoxystyrene, styrene‐p‐chlorostyrene, and styrene‐p‐fluorostyrene copolymers were performed by UV spectrometry. Their absorption bands were investigated either with respect to pure polystyrene or with respect to the homopolymer of the other constituent at the same wavelength. Attempts to analyze copolymers of styrene‐4‐vinylpyridine and styrene‐N‐vinylcarbazole by similar methods were unsuccessful.
Polyphenylquinoxalines containing alkylenedioxy groups
Authors: Havens S. J. , Harris F. W. , Hergenrother P. M. 
Published: April 2003

AbstractA series of new polyphenylquinoxalines (PPQ) containing alkylenedioxy units within the backbone were prepared in high molecular weight forms (ηinh = 0.82–1.5 dL/g). The glass transition temperatures ranged between 203 and 241°C, decreasing with increasing length of the alkylenedioxy groups. Solution‐cast films gave tensile strength, tensile modulus, and elongation at room temperature as high as 14,400 psi, 378,000 psi, and 8.1%, respectively. The PPQ were readily compression molded to provide compact tension specimens that gave fracture energy (GIc) as high as 10.5 in. lb/in.2 Titanium to titanium tensile shear specimens provided average strengths of 4400 psi at 26°C, 3100 psi at 177°C, and 2010 psi at 203°C. The PPQ were resistant to normal aircraft fluids but were soluble in chlorinated solvents.
The evaluation of the surface characteristic of the PET film and fabric treated with PEG–diamine
Authors: Kim Kap Jin , Ko Sohk Won 
Published: April 2003

AbstractPET film treated with PEG–diamine at 130°C was investigated for the aminolysis reaction and the pseudografted PEG content was measured with FTNMR. The hydrophilic properties of the PET film and fabric treated with PEG–diamine were estimated by their surface free energies, water‐wicking time, oily soil releasing, and static electricity. Results obtained indicated that the PEG unit was pseudografted to the PET chain end as a result of the aminolysis reaction of the ester bond of PET by the primary amine radical of PEG–diamine. The pseudografted PET content increased with the aminolysis time [PEG wt % = 2.1147 × t (h)0.4593]. γSP increased very much, γSd decreased a little, and consequently γS, ISWn, and the work of adhesion of water Wa increased with the increasing PEG content. γFW decreased very much, γFO increased a little, and consequently the difference between adhesion tensions of oily soil and water to the specimen (AFO–AFW) increased as the PEG content increased. The contact angle of oily soil to the specimen θO immersed in water increased and consequently θW and WFO/W decreased. Therefore, the PET fabric treated with PEG–diamine had very good water‐wicking, oily soil releasing, and antistatic properties.
Blends containing polymers of epichlorohydrin and ethylene oxide. II. Polyacrylates
Authors: Fernandes A. C. , Barlow J. W. , Paul D. R. 
Published: April 2003

AbstractThe phase behavior of blends of various polyacrylate homopolymers and two commercial ethyl acrylate (EA) and n‐butyl acrylate (nBA) copolymers with polyepichlorohydrin (PECH), poly(ethylene oxide) (PEO), and a copolymer of epichlorohydrin and ethylene oxide [P(ECH/EO)] was examined using differential scanning calorimetry and optical indications of phase separation on heating, i.e., lower critical solution temperature (LCST) behavior. Poly(methylacrylate) (PMA) was shown to be miscible with PECH, PEO, and P(ECH/EO) while only PECH was found to be miscible with the higher polyacrylates: poly(ethyl acrylate), EA copolymer, poly(n‐propyl acrylate), and nBA copolymer. However, even PECH was found to be only partially miscible with poly(n‐butyl acrylate). In general, glass transitions observed by DSC for blends were not as broad as those found in corresponding polymethacrylate blends. All mixtures showed LCST behavior, and, based on this and excess volume measurements, to the extent possible, qualitative conclusions were made concerning the relative strength of the interactions among the various blend pairs. For PECH it appears that the interaction with polyacrylates decreases with increasing size of the alkyl group. The commercial copolymers seem to interact more exothermically with PECH than the corresponding homopolymers. The interaction with PMA is apparently larger for PECH than for PEO or for P(ECH/EO). Interactions for the latter two are about the same. The apparently exothermic interactions between ECH and EO units are not sufficiently strong to preclude miscibility of P(ECH/EO) with PMA. As for the polymethacrylates, it is clear that the chlorine moeity of PECH is needed for miscibility with higher polyacrylates.
Single phase polymer systems: CPVC/styrene copolymer alloys
Authors: Bourland Larry G. , Braunstein David M. 
Published: April 2003

AbstractRandom copolymers of styrene and maleic anhydride are miscible with chlorinated poly(vinyl chloride) [CPVC] in all blended proportions. Miscibility was evident in a single glass transition temperature investigated by thermal and mechanical studies. This degree of miscibility differs from the partial miscibility obtained with PVC/styrene copolymers reported previously, where single phase morphology was present only at low blend proportions. Tailoring of physical properties such as heat resistance, flamability resistance, and processability are achieved by varying the relative proportions of CPVC and styrenic copolymer in this miscible alloy system.
Adhesion quality and extent of mesophase in particulates along the whole viscoelastic spectrum
Authors: Theocaris P. S. , Ponirides P. H. 
Published: April 2003

AbstractThe extent of mesophase, which constitutes the boundary layer between the filler and the matrix of a composite, was defined in this paper along the whole viscoelastic spectrum of the polymeric substance constituting the matrix. The already established two‐term unfolding model1–3 was based on thermodynamic measurements of the heat capacity jumps at the glass transition regions of the filled and unfilled substances in order to define the extent of mesophase. In this paper we dispense ourselves with these delicate measurements, based on Lipatov's theory, and we use values taken from the storage and loss compliances of the composite and its constituents, along the whole viscoelastic spectrum of the composite. It was shown that the extent of the mesophase, necessary to sustain the shearing loading between phases, appearing at the glass transition zone, where the loss‐compliances presented their characteristic peaks of resonance, remained constant and almost independent of the respective values of mechanical properties at this critical region. It was shown that any set of values of the mechanical characteristic quantities, defining the composite and its constituents along the whole viscoelastic spectrum, is sufficient to evaluate the extent of the mesophase, and this boundary layer undergoes only negligible variations. Experimental evidence with typical E‐glass polystyrene and other particulates, at various volume fractions of the filler, yielded a satisfactory coincidence with the results derived by using Lipatov's theory and a constancy of the mesophase thickness along the whole temperature range.