bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heat‐resistant polymers from melt‐processable bisimido‐bisphthalonitriles
Authors: Kumar Devendra , Razdan Uday , Gupta Alka D. 
Published: April 2003

AbstractHeat‐resistant polymers which are processable into void‐free components and suitable for composite applications have been synthesized by thermal/chemical polymerization of four newly developed bisimido‐bisphthalonitriles containing silicon, ether, carbonyl, and hexafluoroisopropylidene groups. Thermal polymerization involving addition reactions was performed at 200–275°C for 2–10 h and then post‐curing at 310°C for 10 h. Polymers VI, VII, VIII, and IX were obtained. The thermal polymerization was monitored using infrared spectroscopy. Thermal polymerization was also carried out in the presence of an aromatic diamine. A polyhexasocyclane (V) was synthesized by condensation polymerization of ether containing bisimido‐bisphthalonitrile with 4,4′‐diaminodiphenyl ether in solvent phenol. The synthesized polymers were evaluated for thermal stability using dynamic thermogravimetric analysis (TGA). Polymers VII, VIII, IX, and X showed thermal decomposition temperature in the range of 475–500°C in nitrogen and air atmosphere. The char yield of the polymers was in the range of 60–69% in nitrogen at 800°C. This study indicated that synthesized thermosetting polymers from ether and keto containing bisimido‐bisphthalo‐nitrile are potential candidates for development of graphite composites. © 1993 John Wiley & Sons, Inc.
Polymer drying. VIII. Molecular interpretations of desorption from polystyrene–liquid systems
Authors: Errede L. A. , Henrich P. J. , Pearson R. , Van Bogart J. W. C. 
Published: April 2003

AbstractThe results obtained in time studies that monitored evaporation from liquid‐saturated poly(styrene‐co‐divinylbenzene) to virtual dryness at temperatures ranging from 20 to 80°C confirm those reported earlier for multireplicated time studies at 23 ± 1°C; i.e., when the residual composition (αt, in sorbed molecules per phenyl group) attains the glassy state composition, the value of αt thereafter is given by a linear combination of no more than six exponential decay functions. The logarithms of the rate constants (ki) for decay of these populations at a given temperature decreased linearly with i, the population identification number in the order of decreasing decay rate. The Arrhenius activation energy (ΔEi) for increase in ki with temperature was characteristic of the sorbed species, but it was independent of i. The logarithms of the frequency factors (Ai) decreased linearly with i, the slope of which was numerically equal to that observed for the corresponding ki relationships, signifying that the stepwise decrease of the latter at a given temperature is attributable primarily to a corresponding incremental decrease in entropy. It is suggested that this reflects discrete changes in the molecular structure of polymeric inclusion complexes formed during the transition from the rubbery to the glassy state, as discussed in the text. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of aromatic poly(ether sulfone)s containing pendant sodium sulfonate groups
Authors: Ueda Mitsuru , Toyota Hidetsugu , Ouchi Takao , Sugiyama Jun‐Ichi , Yonetake Koichiro , Masuko Toru , Teramoto Takero 
Published: April 2003

AbstractPoly(ether sulfone)s containing pendant sodium sulfonate groups were prepared by the aromatic nucleophilic substitution reaction of 4,4′‐dichlorodiphenylsulfone (1) and sodium 5,5′‐sulfonylbis (2‐chlorobenzenesulfonate) (2) with bisphenols (3) in the presence of potassium carbonate in N,N‐dimethylacetamide. A new monomer 2 containing the sodium sulfonate groups was synthesized by the sulfonation of 1 with fuming sulfuric acid. The polycondensation proceeded smoothly at 170°C and produced the desired poly(ether sulfone)s containing the sodium sulfonate with inherent viscosities up to 1.2 dL/g. The polymers were quite soluble in strong acid, dipolar aprotic solvents, m‐cresol, and dichloromethane. The thermogravimetry of the polymers showed excellent thermal stability, indicating that 10% weight losses of the polymers were observed in the range above 460°C in nitrogen atmosphere. Both the glass transition temperatures and hydrophilicity of the polymers increased with increasing their concentrations of sodium sulfonate groups. © 1993 John Wiley & Sons, Inc.
Thermally reversible polymer linkages. II. Linear addition polymers
Authors: Wagener K. B. , Engle L. P. 
Published: April 2003

AbstractThe stepwise addition polymerization reactions of bisazlactones [bis(2‐oxazolin‐5‐one)s] and a variety of 4,4′‐bisphenols have been studied for the purpose of making thermally reversible linear polymers. Thus polymerization occurs at or near room temperature, while depolymerization yielding the two monomer species occurs at elevated temperatures. The synthesis of oligomers in solution without the use of catalyst occurs for the reaction of bisazlactones with bisphenols containing an electron‐withdrawing moiety between the two phenol groups of the bisphenol. These oligomers regenerate the bisphenol and bisazlactone monomers upon heating to 165–200°C for several hours under dry box conditions. In many cases, these reactions follow the same patterns of reactivity observed in model studies. This chemistry may be useful for forming degradable or recyclable polymers, where shortchain prepolymers, or macromonomers, endcapped with azlactone and phenol moieties could be used to form high molecular weight polymers that are thermoreversible. Such a reaction system might also be used for preventing reactions of bisphenols and/or bisazlactones at low temperatures, with the desired reaction initiated by formation of the reactive species at elevated temperatures. Envisioned uses in this case might be thermally triggered crosslinking or polymerization reactions, or temperature controlled drug release. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of oligocyclosiloxanes via the hydrosilation of vinylsilanes and vinylsiloxanes with heptamethylcyclotetrasiloxane
Authors: Chang Pao‐Sun , Hughes Thomas S. , Zhang Yingchao , Webster Geoffrey R. , Poczynok Dana , Buese Mark A. 
Published: April 2003

AbstractThe preparation of oligocyclosiloxanes via hydrosilation reactions has been investigated. Hydrosilation reactions employing heptamethylcyclotetrasiloxane and vinyl‐containing silanes and siloxanes yielded a variety of oligocyclosiloxanes with various numbers of cyclosiloxane rings connected through tri‐, tetra‐, penta‐, hexa‐, hepta‐, or octafunctional junctions. The oligocyclosiloxanes were characterized by gas chromatography, IR spectroscopy, 29Si‐, 1H‐, and 13C‐NMR spectroscopy, elemental analysis, and vapor phase osmometry. The polycyclics were redistributed with hexamethyldisiloxane and the resulting fragments analyzed by gas chromatography. All results were consistent with the formation of isomeric oligocyclosiloxanes due to a lack of absolute regioselectivity of the hydrosilation reaction. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of new block copolymers based on poly(ether sulfone) and polyimides
Authors: Oishi Yoshiyuki , Nakata Shoichi , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractNew poly(ether sulfone)‐polyimide block copolymers were synthesized from α,ω‐diamineterminated poly(ether sulfone) oligomer, aromatic diamines, and aromatic tetracarboxylic dianhydrides by low‐temperature solution polymerization and subsequent thermal imidization. The block copolymers were insoluble in organic solvents. The multiblock copolymers obtained by the two‐pot method showed microphase separation, while the random block copolymers by the one‐pot method had single phase morphology. The mechanical properties of the block copolymers were greatly improved by the introduction of polyimide into the poly(ether sulfone). © 1993 John Wiley & Sons, Inc.
Poly(N‐isopropylacrylamide). I. Interactions with sodium dodecyl sulfate measured by conductivity
Authors: Wu X. Y. , Pelton R. H. , Tam K. C. , Woods D. R. , Hamielec A. E. 
Published: April 2003

AbstractConductometric titration of poly(N‐isopropylacrylamide) (polyNIPAM) with sodium dodecyl sulfate (SDS) gave two apparent transitions labeled C1 and C2. The C1 transition was independent of polyNIPAM concentration in the 0.05–0.3 wt % range, whereas C2 was proportional to the polymer concentration. C1 corresponded to the onset of binding of surfactant with polymer. Arguments based on a simple mass action model for micellization are presented to show that C2, the second transition, is not due to any simple explanation such as being the point above which only free micelles are formed with surfactant addition. The cloud point of polyNIPAM increased with the amount of bound surfactant. This was attributed to electrostatic contribution of bound sulfate groups to the increased solubility of polyNIPAM. © 1993 John Wiley & Sons, Inc.
Studies on thermotropic liquid‐crystalline polymers: Part X. Synthesis and properties of crosslinkable aromatic copoly(ester)s containing conjugated double bonds
Authors: Hsu Keh‐Ying , Chang Teh‐Chou , Li Chen‐Hui 
Published: April 2003

AbstractA series of aromatic copoly(ester)s containing conjugated double bonds was prepared from p‐phenylene bis(acrylic acid) (PPBA) with a mixture of methylhydroquinone (MHQ) and various hydroxycarboxylic acids in the presence of diphenylchlorophosphate (DPCP) and pyridine as a catalyst and solvent. The phase behavior of these polymers was studied by differential scanning calorimetry (DSC) and thermal optical polarized microscopy. Under an optical polarized microscope all copoly(ester)s show a nematic thermotropic liquidcrystalline phase. Upon heating, these polymers undergo a photocrosslinking reaction characterized by IR and solubility analysis. This crosslinking reaction also takes place in the liquid‐crystalline phase with the retention of the nematic order in the final crosslinked solid. © 1993 John Wiley & Sons, Inc.
Synthesis of nylon 6–clay hybrid by montmorillonite intercalated with ϵ‐caprolactam
Authors: Kojima Yoshitsugu , Usuki Arimitsu , Kawasumi Masaya , Okada Akane , Kurauchi Toshio , Kamigaito Osami 
Published: April 2003

AbstractIt was found that montmorillonite was intercalated with ϵ‐caprolactam. X‐ray diffraction revealed that the chain axes of the ϵ‐caprolactam were parallel to the montmorillonite plates. The intercalated montmorillonite was swollen by molten ϵ‐caprolactam at 200°C. ϵ‐Caprolactam and 6‐aminocaproic acid (accelerator) were polymerized with the intercalated montmorillonite at 260°C for 6 h, yielding a nylon 6‐clay hybrid. X‐ray diffraction and transmission electron micrography revealed that the silicate layers of the hybrid were uniformly dispersed in the nylon 6 matrix. Mechanical properties of the hybrid were improved. The strength and the modulus of the hybrid increased compared with the previously reported nylon 6 clay‐hybrid (NCH) synthesized by montmorillonite intercalated with 12‐aminolauric acid. The heat distortion temperature (HDT) of the hybrid was 164°C, which was 12°C higher than that of NCH. © 1993 John Wiley & Sons, Inc.
Photophysics of a polyether containing tetramethylanthracene units
Authors: Bruss J. M. (Tingerthal) , Sahyun M. R. V. , Schmidt E. , Sharma D. K. 
Published: April 2003

AbstractPESA is a rigid rod polymer incorporating anthrylene units in its backbone. The photophysics of PESA in solution are representative of the isolated anthracene chromophore. In the solid state, strong interchain excimer emission is observed. Solid PESA undergoes efficient photocrosslinking which we assign to interchain anthracene dimer formation. Competitive quenching of photocrosslinking by diphenyliodonium hexafluorophosphate suggests that localized singlet excitation energy can migrate among chains until trapped by excimer formation. The excimer state is intermediate in photocrosslinking. © 1993 John Wiley & Sons, Inc.
Synthesis of polyimide and poly(imide‐benzoxazole) in polyphosphoric acid
Authors: Sakaguchi Yoshimitsu , Kato Yasuo 
Published: April 2003

AbstractA polyimide made from 4,4′‐diaminodiphenyl ether (ODA) and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA) was synthesized in polyphosphoric acid. Although the polymerization proceeded heterogeneously, a polyimide with an inherent viscosity of 0.90 was obtained, and a tough and flexible film was made from this polyimide. This polymerization was a one‐step reaction including polycondensation and imidization; this was also confirmed by a model reaction between aniline and phthalic anhydride. Utilizing this polymerization method, 3,3′‐dihydroxy‐4,4′‐diaminobiphenyl and 2 mol of 4‐aminobenzoic acid were reacted in PPA, then BPDA was reacted to obtain an alternate copolymer containing imide and oxazole rings. This reaction gave a homogeneous solution of the poly(imide‐benzoxazole). © 1993 John Wiley & Sons, Inc.
Ozone‐induced graft polymerization onto polymer surface
Authors: Fujimoto Keiji , Takebayashi Yoshihiro , Inoue Hiroyuki , Ikada Yoshito 
Published: April 2003

AbstractOzone‐induced graft polymerization was carried out to improve polymer surfaces. The polymers were exposed to ozone and the surface density of peroxides formed was determined by three methods; iodide, DPPH, and peroxidase method. The peroxide production could be readily controlled by the ozone concentration and the ozone exposure time. In addition, it was dependent on the kind of polymer. Further, it seemed probable that the ozone oxidation introduced peroxides not only on the outermost surface but also into a layer deeper from the outermost surface. Such polymeric peroxides were capable of initiating graft polymerization onto PU. All the physical and biological measurements on the grafted surface indicated that ozone‐induced graft polymerization has effectively made the PU surface covered with the grafted water‐soluble chains, their location being restricted to the film surface region. The interaction of the PU surface with blood components could be greatly reduced by the surface graft polymerization. © 1993 John Wiley & Sons, Inc.
FTIR studies of polyimides. II. Factors affecting quantitative measurement
Authors: Pryde C. A. 
Published: April 2003

AbstractMeasurement of imidization by IR spectroscopy has frequently been reported to give results that are either insensitive to changes in the latter part of the cure or in conflict with observations by other methods. However, an analysis of imide formation using the 1370 cm−1 band (CN stretch) in conjunction with the 1500 cm−1 aromatic band as an internal standard appears capable of giving precise, internally consistent measurements for the most commonly used polyimide structures, for samples that are measured in transmission. Measurements of imide content in ultrathin films by grazing incidence reflection spectroscopy appear to be at least semiquantitative. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of a self‐crosslinkable polymer from cardanol: Autooxidation of poly(cardanyl acrylate) to crosslinked film
Authors: John George , Pillai C. K. S. 
Published: April 2003

AbstractCardanyl acrylate (CA), a monomer that yields crosslinkable copolymers, was synthesized by the reaction of cardanol with acryloyl chloride. A linear polymer was obtained by solution polymerization of the monomer in toluene using 0.8% azobisisobutyronitrile as initiator. Upon removal of solvent, the polymer undergoes crosslinking on exposure to air (or UV light) to give an insoluble transparent film. However, in bulk and suspension polymerization the polymer undergoes in situ crosslinking in the absence of any crosslinking agent. The polymer was characterized by IR, NMR, DSC, and GPC. The crosslinking reaction of soluble polymer on exposure to air at ambient conditions was explained by the hydroperoxide theory. © 1993 John Wiley & Sons, Inc.
Water‐soluble copolymers. XLII. Cationic polyelectrolytes of acrylamide and 2‐acrylamido‐2‐methylpropanetrimethylammonium chloride
Authors: Mccormick Charles L. , Salazar Luis C. 
Published: April 2003

AbstractThe new monomer 2‐acrylamido‐2‐methylpropanetrimethylammonium chloride (AMP‐TAC, M2) has been synthesized. Free radical copolymerization with acrylamide (AM, M1) in feed ratios varying from 10 to 50 mol % AMPTAC gave the cationic ATAM series. Copolymer compositions were determined from 13C‐NMR. The reactivity ratio product r1r2 was found to be 0.62. Molecular weights varied from 1.4 to 16.5 × 106 g/mol for the copolymers. Turbidimetric studies showed aqueous solutions of the copolymers to be phase stable in the presence of CaCl2 and Na2CO3 up to 100°C. Solution behavior was independent of pH in the range of 3 to 11, and temperature in the range of 25 to 60°C. Intrinsic viscosities of the cationic copolymers decreased with the addition of electrolytes; however, some samples showed curvature in plots of intrinsic viscosity versus the inverse square root of ionic strength. © 1993 John Wiley & Sons, Inc.
Synthesis and properties of new block copolymers based on poly(ether sulfone) and aramids
Authors: Oishi Yoshiyuki , Nakata Shoichi , Kakimoto Masa‐Aki , Imai Yoshio 
Published: April 2003

AbstractNew poly(ether sulfone)–aramid block copolymers were synthesized from an α, ω‐diamineterminated poly(ether sulfone) oligomer, aromatic diamines, and aromatic dicarboxylic acid chlorides by the low‐temperature solution polycondensation in N‐methyl‐2‐pyrrolidone. By the introduction of aramid into the poly(ether sulfone), the glass transition temperatures of the block copolymers rose and the mechanical properties were significantly improved. Microphase separation, which often takes place in many block copolymers, did not occur in the present block copolymers. © 1993 John Wiley & Sons, Inc.
Novel nonionic and cationic hydrogels prepared from N‐vinylacetamide
Authors: Akashi Mitsuru , Saihata Shinya , Yashima Eiji , Sugita Shuichi , Marumo Kuniomi 
Published: April 2003

AbstractPoly(N‐vinylacetamide) (polyNVA) hydrogels were prepared by the copolymerization of N‐vinylacetamide (NVA) with divinyl compounds such as methylene‐bis‐acrylamide, methylene‐bis‐NVA, and butylene‐bis‐NVA in a high yield. The resulting hydrogels were more stable than polyacrylamide gel and showed quite a high swelling property in a wide range of pH (1–12) and even in a 5M NaCl solution. They showed not only typical characteristics nonionic hydrogels, but also an amphiphilic property and they swelled well in some organic solvents. When the gels were partially hydrolyzed, cationic hydrogels, i.e., crosslinked poly(NVA‐co‐vinylamine), were collected. The resulting superabsorbent hydrogels absorbed 400 times of water. © 1993 John Wiley & Sons, Inc.
Effects of the polymer‐support on the synthesis of 2,4‐dibromophenyl allyl ether in a triphase catalysis
Authors: Wang Maw‐Ling , Yu Chun‐Chi 
Published: April 2003

AbstractThe synthesis of 2,4‐dibromophenyl allyl ether by reacting allyl bromide with 2,4‐dibromophenol in an organic solvent/alkali solution by triphase catalysis was studied. A macroporous polymer pellet which served as the support of the catalyst was prepared by reacting styrene monomer with chloromethyl styrene and divinylbenzene through suspension polymerization. Tri‐n‐butylamine was immobilized on the surface of the polymer pellet to form the triphase catalysts. Immobilization of the catalyst on the polymer support carried out in a mechanical agitator was suggested to obtain a high catalyst reactivity. In the three‐phase reaction, the effects of agitation speed, and the characteristics of the catalyst pellet which affect the conversion of allyl bromide in the three‐phase catalytic reaction were examined in detail. Based on the experimental data, the optimum operating parameters for preparing the triphase catalyst to get a high yield of 2,4‐dibromophenyl allyl ether were: using a low degree of polymer crosslinking (2%), and small particle size. The yield of the product obtained from the present study is higher than that which was obtained in a two‐phase reaction. © 1993 John Wiley & Sons, Inc.
Optically‐active comb‐branch liquid crystalline polymers having the chiral center in the flexible spacer unit. III. Copolymers of (S)‐2‐(4′‐cyano‐4‐biphenylyloxy)‐1‐methylethoxy ethyl methacrylate and di[6‐(4‐methoxy‐4′‐oxybiphenyl) hexyl]‐2‐methylene butane‐1,4‐dioate
Authors: Cowie J. M. G. , Hunter H. W. 
Published: April 2003

AbstractA new series of copolymers with optically‐active liquid crystalline side chain units has been synthesized from the comonomers (S)‐2‐[2‐(4′‐cyano‐4‐biphenylyloxy‐1‐methylethoxy]ethyl methacrylate (1) and di[6‐(4‐methoxy‐4′‐oxybiphenyl)hexyl]‐2‐methylene butane‐1,4‐dioate (4). Chiral nematic phases were exhibited by two members of the series, rich in monomer 1, while a smectic phase was exhibited in copolymers rich in 4. While it was thought possible that ordered chiral liquid crystalline phases may be induced by copolymerizing chiral mesogenic monomers with mesogenic derivatives of itaconic acid where the high side chain density encourages greater ordering in the system, no evidence of smectic C* phases could be found in the present systems. © 1993 John Wiley & Sons, Inc.
Synthesis and characterization of photosensitive polyimides from methylthiomethyl‐substituted 4,4′‐diaminodiphenylmethanes and 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride
Authors: Chiang Wen‐Yen , Mei Wang‐Ping 
Published: April 2003

AbstractA series of novel polyimides are synthesized by the reaction of 3,3′,4,4′‐benzophenonete‐tracarboxylic dianhydride (BTDA) with four methylthiomethyl‐substituted aromatic diamines: 3‐methylthiomethyl‐4,4′‐diaminodiphenylmethane (I), 3,3′‐dimethylthiomethyl‐4,4′‐diaminodiphenylmethane (II), 3,3′,5‐trimethylthiomethyl‐4,4′‐diaminodiphenylmethane (III), and 3,3′,5,5′‐tetramethylthiomethyl‐4,4′‐diaminodiphenylmethane (IV) in refluxing m‐cresol. The polyimide of diamine I and BTDA carrying only one pendant methylthiomethyl group in a repeating unit is readily soluble in m‐cresol, chloroform, and polar aprotic solvents. Increasing the number of the pendant group results in higher solubility. These fully imidized polyimides are also intrinsically photosensitive. The fraction of photoreactive benzophenone sites that relates to the rate and degree of completion of photocrosslinking reaction increases systematically with the increase of the pendant group content. As the average number of the pendant group in a repeating unit reaches 3, 63% of benzophenone sites are found to be photoreactive. These methylthiomethyl‐substituted polyimides possess moderate tensile strength which falls in the range of 67–81 MPa. As a result of the increase of methylthiomethyl content, this type of polyimide reveals higher glass transition temperature but lower thermal stability due to the considerable dimension of the pendant group and the ready cleavage nature of the CS bond. © 1993 John Wiley & Sons, Inc.
Polyisophthalamides with benzoyl pendent groups: Synthesis, characterization, and evaluation of properties
Authors: Lozano A. E. , De Abajo J. , De La Campa J. G. 
Published: April 2003

AbstractPolyisophthalamides containing benzoyl pendent groups were prepared from 5‐benzoylisophthaloyl chloride and seven aromatic diamines, and their properties were compared with those of unsubstituted polyisophthalamides. The incorporation of one pendent benzoyl group per repeat unit brought about a decrease in the glass transition temperature of 10–30°C, relative to the unmodified polymers, while the thermal resistance (programmed TGA) remained unchanged or went down slightly. Other properties investigated were mechanical properties, solubility, and water absorption. © 1993 John Wiley & Sons, Inc.