bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of ionomeric poly(vinyl butyral)
Authors: Dasgupta A. M. , David D. J. , Misra A. 
Published: April 2003

AbstractA route to synthesizing novel poly(vinyl butyral) ionomers (IPVB), via a condensation polymerization process, has been developed. In the process, ionic groups were permanently incorporated into the poly(vinyl butyral) backbone by using an ion‐containing aldehyde in addition to butyraldehyde during the acetalization of poly(vinyl alcohol). The resulting polymers demonstrated properties typical of ionomer systems, i.e., they behaved as “thermally reversible crosslinked thermoplastics” due to the presence of ionic associations present in the polymers. The ionic associations enabled the polymers to behave as crosslinked materials at ambient temperatures, whereas, at higher temperatures (processing temperatures), the ionic associations were lost, thus allowing the polymers to flow. Consequently, at ambient temperatures, the IPVBs demonstrated increased stiffness as determined from the storage modulus of the polymers, whereas, at higher temperatures, the IPVBs demonstrated moduli and stress‐relaxation properties comparable to those of conventional poly(vinyl butyral). The IPVBs were characterized by a number of techniques including, high resolution NMR spectroscopy (1H, 13C), dilute solution viscometry, dynamic mechanical analysis, and differential scanning calorimetry (DSC). Characterization was done on plasticized and unplasticized IPVBs.
Characterization of the glass transition using a microindenter
Authors: Rodriguez Ferdinand , Long Treva 
Published: April 2003

AbstractThe microindenter described here requires a very small sample (c. 10 mg), can be used with heating rates comparable to those in DSC (i.e., 10°C/min), and gives a large, clearly defined change at the glass transition. The essential features are a needle probe and a linear variable differential transformer (LVDT). By suitably controlling the force on the needle, the rate of heating, and the sample thickness, reproducible results can be obtained. The small sample size permits a relatively fast heating rate. Most mechanical tests (often using oscillating stress and strain) require large samples and a correspondingly long time for temperature equilibration to take place (ASTM D 4065). Another indentation test, the Vicat Softening Temperature (ASTM 1525) also uses a thick (3 mm) sample. Like the Vicat test, the present procedure is best suited to amorphous polymers. The application to plasticized samples of poly(methyl methacrylate) illustrates the utility of the method. The simple, rugged, and inexpensive nature of the apparatus makes it suitable for an under‐graduate experiment in a polymer laboratory course.
The effect of fumed silica upon the reaction of iron octoate and polysiloxanes
Authors: Ishida H. , Dunkers J. 
Published: April 2003

AbstractSilica is a common component in silicone elastomer formulation. Silica is known to have surface hydroxyl groups and the reactions and interactions of these surface groups with various materials have been studied extensively in the past. It is believed that the iron octoate used to combat oxidative embrittlement in silicone elastomer formulations may also react with the surface of silica, specifically fumed silica. Dynamic mechanical spectroscopy (DMS), Fourier Transform Infrared Spectroscopy (FT‐IR), Electron Scanning for Chemical Analysis (ESCA), and Gel Permeation Chromatogrphy (GPC) were used to study the influence of untreated fumed silica and silica treated with dimethylsiloxane species on the iron octoate reaction. The rate of reaction was studied as a function of loading of silica. From analyzing rates of backbone scission and salt consumption, it is found that the iron octoate reacts preferentially with the surface of untreated fumed silica. Conversely, iron octoate appears to have no preferential reaction with the surface of the treated fumed silica.
The effect of castor oil on the structure and properties of polyurethane elastomers
Authors: Saxena P. K. , Srinivasan S. R. , Hrouz J. , Ilavský M. 
Published: April 2003

AbstractSegmented polyurethane elastomers based on a mixture of castor oil and poly(propylene glycol), 4,4'‐diphenylmethane diisocyanate, and 1,4‐butanediol were prepared. The ultimate, thermal, dynamic mechanical behavior and morphology were studied. The use of castor oil shifts the main transition region of the soft phase to higher temperatures (the glass transition temperature Tg increases) improves abrasion resistance and the tensile strength. The multifunctionality of castor oil leads to the crosslinking of the soft segments and a decrease of the sol and swelling of elastomers.
Moisture sorption on the wetting behavior of poly(p‐phenylene terephthalamide) fibers in water and epoxy resin
Authors: Hsieh You‐Lo , Hartzell Mary Michelle , Barrall Geoff 
Published: April 2003

AbstractThe moisture sorption of poly(p‐phenylene terephthalamide) (PPTA) fibers and the effects of moisture on the wetting behavior of these fibers in water and in an epoxy resin were studied. The moisture regains in the Kevlar 149 fibers followed a third order polynomial dependency on increasing relative humidity at 23°C. When preconditioned at 0% relative humidity (R.H.), water wettability of Kevlar 49 fibers was superior to that of Kevlar 149 fibers. Resin wettability of the dried Kevlar 49 fibers, on the other hand, was lower than that of Kevlar 149 fibers. Wettability in water and resin of these two fiber types was affected differently by moisture. Exposure to 97% R.H. moisture level significantly lowered water wettability of Kevlar 49 fibers but did not affect the wettability of Kevlar 149 fibers in water. Resin wettability of Kevlar 49 fibers was improved upon exposure to moisture, but the opposite was observed on Kevlar 149 fibers.
Curing behavior of epoxy resin having hydroxymethyl group and different molecular weight distribution
Authors: Ohtsuka K. , Hasegawa K. , Fukuda A. , Uede K. 
Published: April 2003

Abstracto‐Cresol novolac‐type epoxy resins having hydroxymethyl group were synthesized. These epoxy resins were cured with a mixture of 4,4′‐diaminodiphenylmethane and m‐phenylenediamine (molar ratio, 6:4) as a hardener. Effects of molecular weight distribution of epoxy resins on curing behavior were studied. Curing behavior of epoxy resins with hardener were examined by differential scanning calorimetery (DSC), and cure reaction parameters were obtained. Viscoelastic properties of the cured epoxy resins were studied by dynamic mechanical analyzer. It was found that the lower the average molecular weight of the epoxy resin, that is, the higher the concentration of hydroxymethyl group, the shorter the onset time of exothermal reaction, the higher the rate constant (k), and the lower the activation energy (Ea) were. It was also found that glass transition temperature (Tg) of fully cured epoxy resins was higher than those of fully cured general novolac‐type epoxy resins.
Grafting of poly(ethylene terephthalate) fibers with methacrylic acid using benzoyl peroxide
Authors: Sacak Mehmet , Sertkaya Filiz , Talu Muzaffer 
Published: April 2003

AbstractThe graft copolymerization of methacrylic acid onto poly(ethylene terephthalate) fibers, by the aid of benzoyl peroxide, have been investigated. The graft yield increased up to 85°C, and then decreased with the further increase in temperature. The maximum graft yield was obtained at benzoyl peroxide concentration of 4.0 × 10−3 mol/L. The increase in the concentration of monomer was found to increase the graft yield. The change in the graft yield was followed by the experiments carried out using different water/solvent mixtures. Also, the change in the properties of polye (thylene terephthalate) fibers grafted with methacrylic acid such as moisture regain, density, and diameter were investigated.
Visible laser lights in photoinduced polymerization. VI. Thioxanthones and ketocoumarins as photoinitiators
Authors: Fouassier J. P. , Wu S. K. 
Published: April 2003

AbstractThe efficiency of thioxanthones and ketocoumarins as photoinitiators has been checked in visible laser light‐induced polymerization reactions and discussed in terms of excited‐state reactivity (as revealed by time‐resolved laser spectroscopy). These compounds undergo fast electron transfer reaction in the presence of amines and onium salts. Transient absorption spectra and rate constants of the processes involved have been determined. The combination photoinitiator‐amine‐onium salt appears as very promising for the design of efficient photosensitive systems.
On the synthesis of ethyl‐2‐cyanoacrylate from waste residue
Authors: Denchev Z. Z. , Kabaivanov V. S. 
Published: April 2003

AbstractThe aim of the present study is to clarify some problems concerning the synthesis of additional quantities of ethyl‐2‐cyanoacrylate monomer (ECA) utilizing the waste residue (WR) from the large‐scale depolymerization of ECA oligomers. The composition of WR was established by GPC and IR spectroscopy. WR was found to consist mostly of diethyl dicyanoglutarate (DEDCG) and low molecular weight products of its condensation with paraformaldehyde (pFA). The DEDCG&&hyphen;pFA interaction was studied as a model, and the influence of DEDCG conversion on the average degree of polymerization (xn and xw) of the oligomers formed was also followed. On this basis, it was found that oligomer formation in condensation of WR with pFA is consistent with a stepgrowth mechanism, the polymer chain length being determined by steric hindrance and destructive reactions.
Analysis of plasma polymerization of benzaldehyde
Authors: Zhao Q. , Zhu Y. , Xu Y. , Yao Y. , Liu X. 
Published: April 2003

AbstractPlasma polymerization of benzaldehyde was investigated mainly by infrared spectroscopy. The solubility, wettability, and heat stability for the formed plasma polymer are discussed. Benzaldehyde was plasma‐polymerized to yield films and/or powders. The products contained a large amount of carbonyl‐containing groups, such as aromatic ketone, aliphatic ketone, α, β‐olefinic ketone, and cyclic ketone. The chemical structures of formed polymer were strongly influenced by the plasma parameters and so were its solubility, surface wettability, and heat stability. The polymerization mechanism in plasma for benzaldehyde is discussed on the basis of the infrared analyses of the formed polymers at different plasma conditions.
Evaluation of cure conditions for polyimide thin films by pyrolysis–mass spectrometry
Authors: Johnson Eric T. 
Published: April 2003

AbstractFilms of a BTDA–mPDA–ODA polyimide copolymer (DuPont Pyralin PI‐2555) were spincoated onto silicon wafers and cured at either 300 or 350°C. Films cured at each temperature were then analyzed by various pyrolysis mass spectrometric methods. Low‐temperature pyrolysis mass spectrometry showed that polyimide films cured at the lower temperature contained more residual water and N‐methyl pyrrolidone solvent than did the films cured at the higher temperature. High‐temperature pyrolysis mass spectrometry of the two samples showed subtle differences in the mass spectrum of the polyimide pyrolysate under electron impact (EI) ionization conditions. Principal components analysis was used to differentiate between the EI mass spectra of the high‐and low‐temperature cured films. Several pyrolysis products, primarily aromatic hydrocarbon and heterocyclic fragments, were separated and identified by gas chromatography/mass spectrometry.
Hard elastic behavior in polyurethane foams
Authors: Kau C. , Huber L. , Hiltner A. , Baer E. 
Published: April 2003

AbstractHard elastic behavior is characterized by high porosity and high recoverability from large strain, and initial Hookean elasticity was discovered in polyurethane foams containing styrene–acrylonitrile (SAN) copolymer particles. The presence of SAN particles introduces a heterogeneous morphology, and when the foam was strained in the SEM, it was observed that the struts became highly porous with profuse voiding nucleated by the SAN particles. It was found that these flexible polyurethane foams had a similar morphological structure in the strained struts as did the typical hard elastic materials. The phenomenon of stress depression, when foam specimens under stress were subjected to nonswelling liquids, was utilized to probe the role of surface stress in these hard elastic foams. An analytic methodology established for other highly porous hard elastic materials based on stress depression was utilized to obtain the average distance between voids in the struts. The calculated values were in good agreement with direct scanning electron microscopy observations, confirming that voiding initiated at the boundaries of SAN particles.
Dynamic light‐scattering studies of poly(γ‐benzyl α, l‐glutamate)–benzyl alcohol system
Authors: Shukla Premal , Muthukumar M. , Langley Kenneth H. 
Published: April 2003

AbstractWe report the concentration and temperature dependencies of the diffusion coefficients obtained from dynamic light‐scattering studies for the poly(γ‐benzyl α, l‐glutamate)‐benzyl alcohol (PBLG–BA) system. These studies were made at dilute and semidilute polymer concentrations, mainly in the isotropic phase. The measured translational and rotational diffusion coefficients in dilute solutions are consistent with predictions based on wormlike chain models. The mutual diffusion coefficient in semidilute solutions shows a marked deviation from scaling predictions, demonstrating the strong coupling between the translational and rotational motions. The measured time evolution of the scattered intensity after the PBLG–BA system is suddenly quenched into the gel phase demonstrates that aggregation is a significant mechanism in the formation of the gel phase.
Chemical modification of dialysis membrane based on poly(acrylonitrile–methylmethacrylate–sodium vinylsulphonate)
Authors: Godjevargova Z. , Dimov A. , Petrov St. 
Published: April 2003

AbstractPoly(acrylonitrile–methylmethacrylate–sodium vinylsulphonate) membranes were subjected to modification with a view to improve their dialysis properties. Hydroxylamine and diethylaminoethylmethacrylate were used as modifying agents. As a result of the modification, nitrile groups depending on the modifying agent were partially converted to primary amine, oxime, and tertiary amine groups. The newly formed functional groups provide the membrane more hydrophvlic properties and the permeability of the membranes substantially increases. The appearances of the NH2 and oxime groups were identified by IR spectroscopy. The primary as well as tertiary amino groups were determined quantitatively by potentiometric titration. The pore size distribution of the initial as well as modified membranes were compared. The mentioned modifying agents appeared to be very prospective to improve the dialysis characteristics of the ter‐PAN membranes.
Invariant kinetic parameters of polymer thermolysis. IV. Influence of fire‐retardant additives on polypropylene thermolysis
Authors: Vyazovkin S. V. , Bogdanova V. V. , Klimovtsova I. A. , Lesnikovich A. I. 
Published: April 2003

AbstractAnalyzing the transformation‐degree dependence of the effective activation energy, we have studied the thermolysis gross kinetics of polypropylene (PP)‐based fire‐resisting composition and a synergetic mixture of fire‐retardant additives: antimony oxide and hexabrominecyclododecane (HBCD). The addition to PP of individual HBCD and in a mixture with antimony oxide increases the activation energy at the initial stage of thermolysis, which is attributed to the ability of fire‐retardant additives to impede destruction initiated by oxidation. The investigation of the process proceeding in PP prior to the onset of decomposition in the presence of fire‐retardant additives has shown that these additives stimulated crosslinking of polymer chains. The addition to PP synergetic mixture gives the greatest—compared to its individual components—content of the crosslinked fraction (10%), whose presence is likely to inhibit the proceeding of thermolysis by the oxidation mechanism.
Structure and physical properties of epoxide‐treated tussah silk fibers
Authors: Tsukada Masuhiro , Goto Yoko , Freddi Giuliano , Matsumura Masaaki , Shiozaki Hideki , Ishikawa Hiroshi 
Published: April 2003

AbstractThe structural characteristics and physical properties of epoxide‐treated tussah silk fibers from Antheraea pernyi silkworm are discussed in relation to the increasing weight gain values. Ethyleneglycol diglycidylether (E) and glycerin diglycidylether (G) were used as modifying agents. The noticeably high weight gain values (about 140%) obtained were attributed to the catalytic effect of SCN− anion absorbed by the fibers during the pretreatment under reduced pressure conditions. The amino acid analysis showed that epoxide G exhibited a slightly higher reactivity toward tyrosine, while arginine preferably reacted with epoxide E. The peak of loss modulus (E″) determined by dynamic viscoelastic measurements became broader and its position linearly shifted to lower temperature when the weight gain increased, and a minor peak appeared in the low‐temperature region below 50°C. Differential scanning calorimetry (DSC) thermograms showed that the position of the decomposition peak of modified silk fibers shifted to lower temperature with increasing weight gain values. The minor and broad endothermic peaks, appearing in the reference sample at about 234 and 290°C, disappeared by epoxide treatment. X‐ray diffraction patterns of tussah silk fibers suggested that the epoxide treatment does not affect directly the crystalline regions but causes a decrease of molecular orientation in the amorphous regions. Both briefringence (Δn) and isotropic refractive index (niso) of tussah silk fibers decreased by the reaction with epoxides, although with different rate and extent, confirming the decrease of average molecular orientation. The extent of decrease of strength and elongation depends on the kind of epoxide and on the weight gain value. Epoxide‐treated tussah silk fibers did not show significant changes of surface characteristics as the weight gain values attained up to 60%.
Kinetic studies on anaerobic initiated polymerization
Authors: Smith J. D. B. 
Published: April 2003

AbstractUsing a model reaction system consisting of cumene hydroperoxide, N,N‐dimethyl‐p‐to‐luidine and O‐benzoic sulfimide in toluene solvent (without reactive acrylic monomer), attempts have been made to understand the initiation mechanism operating during anaerobic polymerization. In these studies, the instrumental techniques of visible spectroccopy (VS), high performance liquid chromatography (HPLC) and infrared spectroscopy (IR) were employed.Valuable kinetic data have been obtained using these three instrumental techniques. HPLC studies have shown conclusively that the N,N‐dimethyl‐p‐toluidine (N,N‐DMpT) component is significantly depleted during the initiation step of the anaerobic process. By way of contrast, the benzoic sulfimide (BS) concentration was found to be essentially unchanged during initiation.Visible spectral changes with the model anaerobic solutions indicate that the initiation mechanism may involve radical‐ionic species derived from N,N‐DMpT rather than free radical reactive intermediates. Increasing the acidity of the reaction solution, with addition of acetic acid, appears to accelerate the initiation rate under anaerobic conditions.
Inhibition of deterioration of plastics by hydroaromatics
Authors: Kubo Junichi 
Published: April 2003

AbstractBased on our previous works concluding that the addition of hydrogen‐donating hydroaromatics is effective in inhibiting the deterioration of hydrocarbons, heavy hydroaromatics from petroleum (HHAP) that were produced by hydrogenating highly aromatic heavy oil containing partly hydrogenated condensed aromatic rings were examined by the addition to high‐density polyethylene (PE), isotactic polypropylene (PP), and poly(vinyl chloride) (PVC, MW: 1300) after confirming its prominent hydrogen‐donating ability. The following results were obtained by the deterioration tests and melt‐flow tests: (1) Clear inhibiting effects could be found on preservation of elongation and tensile strength by the addition of 0.1% and 0.5% of HHAP to PE. (2) Cross‐linking of PE was restricted by the addition of HHAP. (3) Obvious effects could be found on preservation of elongation and tensile strength by the addition of 0.5% of HHAP to PP, but 0.1% of HHAP was not so effective. (4) Melt‐flow rate of PP at 270°C supported the results of the deterioration tests at 120°C. (5) Color changes were remarkably improved by the addition of HHAP to PVC (at 160°C, 140 min). From these results, hydrogen donation from hydroaromatics can be considered effective in inhibiting the deterioration of PE, PP, and PVC.
Surface properties of polymethylenediamine‐fixed styrene/acrylic acid copolymer latex
Authors: Tamai H. , Kiyota H. , Suzawa T. 
Published: April 2003

AbstractSurface charge density, ζ‐potential, and dispersion stability of polymethylenediamine (PMD)‐fixed styrene/acrylic acid copolymer [P(St/AA)] latex were investigated. PMD‐fixed P(St/AA) latices are amphoteric and have isoelectric points at pH 4–7. Though the flocculations were observed at neutral pH, the pHs where the flocculation rates were maximum are slightly higher than were the isoelectric points. This result suggests the influence of the expansion of PMD‐fixed polymer layer surrounding the particles on the flocculation. The fixation of PMD to the surface of P(St/AA) latex lowers the dispersion stability for high electrolyte concentration.
Preparation of a plasma polymer containing phosphine complexed nickel by concurrent nickel evaporation
Authors: Morosoff N. C. , Clymer S. D. , Crumbliss A. L. 
Published: April 2003

AbstractThis article describes one of the first examples of concurrent metal evaporation and substituted hydrocarbon plasma polymerization as a general method for preparing thin films containing a metal coordinated to a plasma polymer. In this report, the evaporation of Ni into a triallylphosphine (TAP) glow discharge is described Deposition of a plasma polymer with concurrent reaction of Ni atoms with phosphine groups forms nickel containing triallylphosphine plasma polymer, NiTAPPP. The chemical nature of the product is derived on the basis of infrared spectra taken of the film as formed and after reaction with air, CO, and NO. The extent of the reaction is deduced from gravimetric data obtained during reaction with CO and with NO; each case was followed by evacuation of the gas. The CO gravimetric data also suggest that uncoordinated Ni is predominantly formed at high (Ni evaporation rate)/(plasma polymer deposition rate) ratios; coordinated Ni predominates at low values of this parameter. The ESCA spectra are also obtained for this plasma polymer (NiTAPPP) as well as for that described in the previous paper, in which TAP is plasma polymerized (yielding TAPPP) and subsequently reacted with Ni(CO)4 (TAPPP + Ni(CO)4). In both cases, it was found that Ni is oxidized on contact with air. After such air exposure, ESCA spectra reveal the presence of residual NiP moieties on the surface of TAPPP + Ni(CO)4, but not of NiTAPPP. This is attributed to the greater reactivity of the coordinatively unsaturated Ni sites postulated for NiTAPPP.