bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biodegradable blends of poly(ε‐caprolactone) with α‐chitin and chitosan: specific interactions, thermal properties and crystallization behavior
Authors: Senda Toshihiko , He Yong , Inoue Yoshio 
Published: August 2002

AbstractFilms of poly(ε‐caprolactone) (PCL) blends with α‐chitin and chitosan were prepared as completely biodegradable polyester/polysaccharide composites. DSC thermal analysis revealed that the crystallization of PCL was suppressed by blending with α‐chitin and chitosan. The specific interaction between PCL and polysaccharides was investigated by FTIR spectroscopy. The PCL carbonyl vibration bands could be resolved into three components: crystalline, amorphous and interacting. The FTIR spectra indicated that there were hydrogen bonding interactions between PCL and polysaccharides, and that polysaccharides suppressed the crystallization of PCL, consistent with the results obtained by DSC.© 2001 Society of Chemical Industry
The effect of benzenesulfonamide plasticizers on the glass transition temperature of an amorphous aliphatic polyamide
Authors: Groote Ph De , Devaux J , Godard P 
Published: August 2002

AbstractThe plasticizing effect of benzenesulfonamides (BSAs) on an amorphous aliphatic polyamide (AAPA) has been studied using dynamic mechanical analysis of copper‐supported spin‐coated mixtures. It follows that N‐(n‐butyl)BSA (BBSA), an amorphous liquid hydrogen bonding BSA, is fully miscible with AAPA because their mixtures are characterized by a single glass transition (Tg) throughout the compositional range. The Tg–composition dependence, however, is not linear because experimental results suggest a 20 K fall in Tg occurring around 0.65 BBSA units per amide unit, which coincides with the system shifting from a polymer‐like to a liquid‐like glass‐forming material. When considering a crystallizable hydrogen‐bonding plasticizer such as ethylBSA (EBSA), AAPA/EBSA mixtures become fully crystalline at a 1.3 EBSA unit per amide group. Nevertheless, melting point depression together with the single Tg observed throughout the compositional range on quenched (and therefore amorphous) samples confirms the miscibility of AAPA chains with the plasticizer. N,N‐DialkylBSAs, which lack the sulfonamide proton and therefore the possibility of hydrogen bonding with amide groups, quickly phase separate from AAPA, the glass transition of the latter staying mainly unaffected apart from a small (9 K) decrease at 10–15 mol% plasticizer.© 2001 Society of Chemical Industry
Thermal and mechanical properties of diglycidylether of bisphenol A/ trimethylolpropane triglycidylether epoxy blends cured with benzylpyrazinium salts
Authors: Park Soo‐Jin , Kim Taek‐Jin , Kim Hak‐Yong 
Published: August 2002

AbstractThe effect of blend composition on thermal stability and mechanical properties of diglycidylether of bisphenol A (DGEBA)/trimethylolpropane triglycidylether (TMP) epoxy blends cured with benzylpyrazinium salts (N‐benzylpyrazinium hexafluoroantimonate, BPH) as a thermal latent catalyst was investigated. The thermal stability, characterized by the initial decomposition temperature, temperature of maximum rate of weight loss, integral procedural decomposition temperature, and activation energy for decomposition, increase in DGEBA‐rich compositions. This could be due to the long repeat unit and stable aromatic ring in the DGEBA. The mechanical properties are also discussed in terms of the fracture toughness (KIC), flexural and impact tests for the blend composition studied. The addition of TMP into DGEBA gives systematic improvements in fracture toughness, which results from the increase in aliphatic and flexible chain segments of TMP.© 2002 Society of Chemical Industry
Psychometric data for teacher judgments regarding the learning behaviors of primary grade children
Authors: Crosby Edward G. , French Joseph L. 
Published: August 2002

AbstractThe psychometric properties of the Classroom Performance Profile (CPP), a teacher rating scale, were investigated using primary grade children from economically at‐risk families. Students were rated as they progressed from kindergarten through third grade. The CPP demonstrated high internal consistency yielding Cronbach alpha coefficients for the total score of at least .96. CPP ratings were correlated with scores from the Woodcock‐Johnson Psycho‐Educational Battery–Revised: Tests of Achievement and the Social Skills Rating System–Teacher Form, Elementary Level. Results suggest that the CPP ratings were positively correlated with measures of academic achievement, academic competence, and social skills, and negatively correlated with problem behaviors. © 2002 Wiley Periodicals, Inc.
Best practices in the identification of gifted students with learning disabilities
Authors: McCoach D. Betsy , Kehle Thomas J. , Bray Melissa A. , Siegle Del 
Published: August 2002

AbstractIn recent years, researchers and practitioners have become increasingly interested in students who have both learning disabilities and intellectual gifts. Intellectually gifted students are defined as those who demonstrate outstanding ability to grapple with complexity, or superior academic potential. The definition of learning disability states that the level of performance in a particular academic area is substantially below what would be expected based on one's general intellectual ability and that this incongruity cannot be explained by lack of educational opportunity in that academic area. This article explores several controversial issues surrounding the identification of students as both gifted and learning disabled. How does a discrepancy manifest itself in a student who is intellectually gifted? Do gifted students with learning disabilities experience masking effects? How can we effectively identify intellectually gifted students with learning disabilities? In addition, we argue against the use of profile analysis to identify gifted students with learning disabilities. Finally, we propose guidelines for school psychologists to identify students with intellectual gifts and learning disabilities, and we provide suggestions for how to best serve this unique population of students within the school environment. © 2001 John Wiley & Sons, Inc.
Effects of pure non‐ionic and mixed non‐ionic–cationic surfactants on the rates of hydrolysis of phenyl salicylate and phenyl benzoate in alkaline medium
Authors: Khan M. Niyaz , Ismail Emran , Yusoff M. Rapandy 
Published: August 2002

AbstractThe pseudo‐first‐order rate constants (kobs) for the alkaline hydrolysis of phenyl benzoate (PB) decrease monotonically from 72.0 × 10−4 to 7.4 × 10−4 s−1 with increase in the concentration of polyoxyethylene 23 lauryl ether ([C12E23]T) from 0.0 to 0.01 M at 0.01 M NaOH and 35 °C. The results fit satisfactorily to a pseudophase model of micelles. The values of kobs for the hydrolysis of ionized phenyl salicylate (PS−) are almost independent of [C12E23]T within the range 0.0–0.02 M at 0.01 and 0.03 M NaOH and 35 °C. The rate of alkaline hydrolysis of PB appears to be negligible in the micellar pseudophase than in the aqueous pseudophase, which is ascribed to the extremely low concentration of HO− in the micellar region of micellized PB molecules. The values of kobs for hydrolysis of PB and PS− at 0.01 M NaOH become almost zero at ≥0.02 and ≥0.03 M C12E23, respectively. The effects of mixed C12E23–CTABr on kobs for the alkaline hydrolysis of PB reveal that mixed micelles behave like pure CTABr micelles within the [C12E23]T range 0.0–5 × 10−4 M whereas an increase in [C12E23]T from ≥7 × 10−4 to 0.02 M decreases kobs at 0.006, 0.01, 0.02 and 0.03 M CTABr. However, the values of kobs are significantly higher at [CTABr]T = 0.006, 0.01, 0.02 and 0.03 M than at [CTABr]T = 0 in the presence of [C12E23]T in the range >5 × 10−4 –0.02 M. An increase in [C12E23]T from 0.0 to 0.015 M causes nearly a twofold increase in kobs at 0.01, 0.02 and 0.03 M CTABr and 0.01 M NaOH. Copyright © 2001 John Wiley & Sons, Ltd.
Mechanistic studies of the oxidation of substituted phenethyl alcohols by N‐metallo‐N‐haloarylsulphonamides: kinetic isotope studies
Authors: Rangappa Kanchugarakoppal S. 
Published: August 2002

AbstractThe oxidation of para‐substituted phenethyl alcohols (PEA, 2) by N‐metallo‐N‐haloarylsulphonamides (1) in the presence of dilute HCl to the corresponding phenacetaldehydes (4) is first order with respect to oxidant (1) and [H+] and a fractional order each in [PEA] and [Cl−]. Addition of the reaction product (3), ionic strength variations and variation of dielectric constant of the medium had no effect on the rate. The oxidation of PhCH2CD2OH (2) exhibited a substantial primary kinetic isotope effect (kH/kD = 5.83). The rates correlate satisfactorily with the Hammett free energy relationship. The activation parameters ΔH≠, ΔS≠, ΔG≠ and logA were calculated for the reaction. The proposed mechanism is consistent with the observed results. Copyright © 2001 John Wiley & Sons, Ltd.
In situ atom transfer radical polymerization of styrene with a tetraethylthiuram disulfide/copper bromide/2,2′‐bipyridine initiating system
Authors: Li Peng , Qiu Kun‐Yuan 
Published: August 2002

AbstractThe living radical polymerization of styrene in bulk was successfully performed with a tetraethylthiuram disulfide/copper bromide/2,2′‐bipyridine (bpy) initiating system. The initiator Et2NCS2Br and the catalyst cuprous bromide (CuBr) were produced from the reactants in the system through in situ atom transfer radical polymerization (ATRP). A plot of natural logarithm of the ratio of original monomer concentration to monomer concentration at present, ln([M]0/[M]) versus time gave a straight line, indicating that the kinetics was first‐order. The number‐average molecular weight from gel permeation chromatography (GPC) of obtained polystyrenes did not agree well with the calculated number‐average molecular weight but did correspond to a 0.5 initiator efficiency. The polydispersity index (i.e., the weight‐average molecular weight divided by the number‐average molecular weight) of obtained polymers was as low as 1.30. The resulting polystyrene with α‐diethyldithiocarbamate and ω‐Br end groups could initiate methyl methacrylate polymerization in the presence of CuBr/bpy or cuprous chloride/bpy complex catalyst through a conventional ATRP process. The block polymer was characterized with GPC, 1H NMR, and differential scanning calorimetry. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4001–4008, 2001
Microstructure of glycidylmethacrylate/vinyl acetate copolymers by two‐dimensional nuclear magnetic resonance spectroscopy
Authors: Brar A. S. , Yadav Anil 
Published: August 2002

AbstractGlycidylmethacrylate/vinyl acetate copolymers were prepared by solution polymerization with benzene as a solvent and benzoyl peroxide as an initiator. Copolymer compositions were determined from 1H NMR spectra, and comonomer reactivity ratios were determined by the Kelen–Tudos (KT) method and the nonlinear least‐squares error‐in‐variable method (EVM). The reactivity ratios obtained from KT and EVM were rG = 37.4 ± 12.0 and rV = 0.036 ± 0.019 and rG = 35.2 and rV = 0.03, respectively. Complete spectral assignments of 13C and 1H NMR spectra were done with the help of distortionless enhancement by polarization transfer and two‐dimensional 13C–1H heteronuclear single quantum coherence and total correlation spectroscopy. The methyl, methine, and methylene carbon resonance showed both stereochemical and compositional sensitivity. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4051–4060, 2001
Photoswitchable architectural polymer: Toward azo‐based polyamidoamine side‐chain dendritic polyester
Authors: Ghosh Samaresh , Banthia Ajit K. 
Published: August 2002

AbstractA versatile approach to the synthesis of novel polyamidoamine (PAMAM) side‐chain dendritic polyester (SCDPE) possessing azobenzene motifs in the polymeric core is described and displayed reversible cis–trans (E/Z) isomerization upon exposure to UV light. A polymerization reaction was conducted in solution using ester‐terminated PAMAM dendritic diol (1a, G 3.5) and azobenzene dicarboxylic acid chloride in the presence of triethylamine. PAMAM dendritic diol 1a as well as SCDPE (1) were thoroughly characterized by means of IR and NMR (1H and 13C) spectroscopies. The intrinsic viscosity of 1 at 36 °C in CHCl3 was found to be 0.38 dl/g. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4182–4188, 2001
Polyimides based on 2,5‐bis(4‐aminophenoxy)biphenyl
Authors: Yang Chin‐Ping , Chen Ruei‐Shin 
Published: August 2002

AbstractA diamine monomer II, 2,5‐bis(4‐aminophenoxy)biphenyl, was prepared through a nucleophilic substitution reaction of phenylhydroquinone and p‐chloronitrobenzene in the presence of potassium carbonate in N,N‐dimethylformamide, followed by catalytic reduction with hydrazine and Pd/C. A series of all‐aromatic, organosoluble polyimides bearing pendent phenyl groups were synthesized from the diamine with six kinds of commercial dianhydrides via a conventional two‐stage process. For improving solubility of polypyromellitimide, copolypyromellitimides with arbitrary solubilities were prepared from II and a pair of dianhydrides, which were mixed at certain molar ratios. These polymers showed good solubilities in N‐methyl‐2‐pyrrolidone and m‐cresol. The softening temperatures of these polyimides were recorded between 206 and 269 °C. Polymers had glass‐transition temperatures at 230–286 °C and 10% weight‐loss temperatures above 521 °C in air or nitrogen atmospheres. Their films had high tensile moduli and strengths. Excellent properties of these polyimides are attributed to the incorporation of the pendent phenyl group in diamine II. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 429–438, 2002; DOI 10.1002/pola.10116
Benzoyl peroxide‐initiated copolymerization of citronellol and vinyl acetate
Authors: Pandey Prachi , Srivastava A. K. 
Published: August 2002

AbstractThe radical copolymerization of citronellol with vinyl acetate (VA) in xylene at 60 ± 0.1 °C for 90 min in the presence of benzoyl peroxide follows ideal kinetics and results in the formation of an alternating copolymer as demonstrated by the values of the reactivity ratios [r1 (VA) = 0.02 and r2 (citronellol) = 0.0002], which have been calculated with the Kelen–Tüdos method. The overall activation energy is computed to be 75 kJ/mol. The IR spectrum of the copolymer shows the presence of bands at 3400 cm−1 due to an alcoholic group and 1750 cm−1 due to a 〉CO group. The values of the Mark–Houwink constants for this copolymer system have been determined with gel permeation chromatography to be α = 0.375 and K = 2.4 × 10−4. The glass‐transition temperature, determined with differential scanning calorimetry, is 68.32 °C. The mechanism has been elucidated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1243–1252, 2002
Formation of polymeric micelles with amino surfaces from amphiphilic AB‐type diblock copolymers composed of poly(glycolic acid lysine) segments and polylactide segments
Authors: Ouchi Tatsuro , Miyazaki Hidetake , Arimura Hidetoshi , Tasaka Fumitaka , Hamada Atsushi , Ohya Yuichi 
Published: August 2002

AbstractAmphiphilic AB‐type diblock copolymers composed of hydrophobic poly(L‐lactide) (PLA) segments and hydrophilic poly(glycolic acid lysine) [poly(Glc‐Lys)] segments with amino side‐chain groups self‐associated to form PLA‐based polymeric micelles with amino surfaces in an aqueous solution. The average diameter of the loose core–shell polymeric micelles for poly(Glc‐Lys) [number‐average molecular weight (Mn) = 1240]‐b‐PLA (Mn = 7000) obtained by a dimethyl sulfoxide/water dialysis method was estimated to be about 50 nm in water by dynamic light scattering measurements. The size and shape of the obtained polymeric micelles were further observed with transmission electron microscopy and atomic force microscopy. To investigate the possibility of applying the obtained PLA‐based polymeric micelles as bioabsorbable vehicles for hydrophobic drugs, we tested the entrapment of drugs in poly(Glc‐Lys) (Mn = 1240)‐b‐PLA (Mn = 7000) micelles and their release with doxorubicin as a hydrophobic drug. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1426–1432, 2002
Highly isotactic polymethacrylates through radical polymerization of methacrylate esters of some ortho‐bridged triaryl carbinols
Authors: Hatziyiannakou Athina , Froussios Cleanthis 
Published: August 2002

AbstractThe polymerization of 9‐phenyl‐10,10‐dioxo‐thioxanthen‐9‐yl and 9‐phenyl‐10‐oxo‐9,10‐dihydroanthracen‐9‐yl methacrylates obtained under radical initiation (α,α‐azobisisobutyronitrile) in benzene solution proceeds with high isotactic specificity to afford homopolymers with a triad mm content higher than 95%, having presumably a helical main‐chain structure and showing significant resistance to solvolytic degradation in methanol. 9‐Phenyl‐10,10‐dipropyl‐9,10‐dihydroanthracen‐9‐yl methacrylate similarly affords isotactic polymers with an mm of 98% but is much less durable in contact with methanol. The high isotacticity observed for the aforementioned polymethacrylates as well as for poly(1‐phenyl‐dibenzosuberyl methacrylate), previously reported in the literature, reveal a tendency of ortho‐bridged triarylcarbinols to enforce isotacticity on their methacrylate polymers obtained under radical initiation. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1180–1186, 2001
Melt‐processable poly(oxyphenylalkanoate): Synthesis, properties, and in vitro degradation of poly(4‐oxyphenylacetate)
Authors: Prasad V. S. , Pillai C. K. S. , Kricheldorf H. R. 
Published: August 2002

AbstractThe homopolyester of 4‐hydroxyphenylacetic acid (HPAA) was synthesized by one‐pot, slurry‐melt, and acidolysis melt polymerization techniques and was characterized by its inherent viscosity and IR and NMR spectra. Differential scanning calorimetry (DSC), polarizing light microscopy (PLM), and wide‐angle X‐ray diffraction (WAXD) studies of the homopolymer were carried out for its thermal and phase behavior. The results indicated that the yield and molecular weight of the polymer depended on the method of preparation; moreover, the acidolysis melt polymerization of the pure acetoxy derivative of HPAA was the best method for the preparation of high molecular weight poly(4‐oxyphenylacetate) (polyHPAA) without side reactions. DSC and PLM studies also showed that the thermal and optical properties depended largely on the polymerization conditions and inherent viscosity values. PolyHPAA did not show a clear texture typical of liquid‐crystalline polymers, whereas after cooling from the melt, structures similar to spherulitic crystals were observed. WAXD patterns showed a crystalline nature. The in vitro degradability of the polymer was also studied via the water absorption in buffer solutions of pH 7 and 10 at 30 and 60 °C; this was followed by Fourier transform infrared, inherent viscosity, DSC, thermogravimetric analysis, WAXD, and scanning electron microscopy techniques. Unlike Vectra®, which showed no degradation, polyHPAA showed an increase in hydrolytic degradation from 5.0 and 6.0% at 30 °C to 12.5 and 15.0% at 60 °C after 350 h in buffer solutions of pH 7 and 10, respectively. The results indicated a possible biomedical prosthetic application of poly(oxyphenylalkanoate)s such as polyHPAA with better crystallinity coupled with degradability as a substitute for poly(hydroxyalkanoates). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2430–2443, 2001
Synthesis and properties of a novel, liquid, trifunctional, cycloaliphatic epoxide
Authors: Xie Meiran , Wang Zhonggang , Zhao Yunfeng 
Published: August 2002

AbstractA novel cycloaliphatic triepoxide, 1,1‐bis(2′,3′‐epoxycyclohexyloxymethyl)‐3,4‐epoxycyclohexane (II), and its precursor, 1,1‐bis(2′‐cyclohexenyloxymethyl)‐3‐cyclohexene, were synthesized. Their chemical structures were confirmed with IR spectroscopy, elemental analysis, and 1H NMR spectroscopy. II was easily cured with hexahydro‐4‐methylphthalic anhydride with 1,3,5‐triethylhexahydro‐s‐triazine as a curing accelerator. The physical properties of the cured product were examined with thermomechanical analysis, thermogravimetric analysis, and dynamic mechanical analysis. Compared with the commercial diepoxide ERL‐4221 under the same curing conditions, the cured product based on II showed a much higher glass‐transition temperature (198 °C), a higher crosslinking density (2.08 × 10−3 mol/cm3), and a lower coefficient of thermal expansion [6.2 × 105(/°C)]. II may become a promising candidate material for modern microelectronic packaging. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2799–2804, 2001
Synthesis and characterization of novel polyimide from bis‐(3‐aminophenyl)‐4‐(trifluoromethyl)phenyl phosphine oxide
Authors: Jeong Kwang Un , Jo Young‐Jun , Yoon Tae‐Ho 
Published: August 2002

AbstractA novel diamine, bis‐(3‐aminophenyl)‐4‐(trifluoromethyl)phenyl phosphine oxide (mDA3FPPO), containing phosphine oxide and fluorine moieties was prepared via the Grignard reaction from an intermediate, 4‐(trifluoromethyl)phenyl diphenyl phosphine oxide, that was synthesized from diphenylphosphinic chloride and 4‐(trifluoromethyl)bromobenzene, followed by nitration and reduction. The monomer was characterized by Fourier transform infrared (FTIR), 1H NMR, 31P NMR, 19F NMR spectroscopies; elemental analysis; melting point measurements; and titration and was used to prepare polyimides with a number of dianhydrides such as pyromellitic dianhydride (PMDA), 5,5′‐[2,2,2‐trifluoro‐1‐(trifluoromethyl)ethyliden]‐bis‐1,3‐isobenzofuranedione (6FDA), 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), and 4,4′‐oxydiphthalic dianhydride (ODPA). Polyimides were synthesized via a conventional two‐step route; preparation of polyamic acids, followed by solution imidization, and the molecular weight were controlled to 20,000 g/mol. Resulting polyimides were characterized by FTIR, NMR, DSC, and intrinsic viscosity measurements. Refractive‐index, dielectric constant, and adhesive properties were also determined. The properties of polyimides were compared with those of polyimides prepared from 1,1‐bis‐(4‐aminophenyl)‐1‐phenyl‐2,2,2‐trifluoroethane (3FDAm) and bis‐(3‐aminophenyl) phenyl phosphine oxide (mDAPPO). The polyimides prepared from mDA3FPPO provided high glass‐transition temperatures (248–311 °C), good thermal stability, excellent solubility, low birefringence (0.0030–0.0036), low dielectric constants (2.9–3.1), and excellent adhesive properties with Cu foils (107 g/mm). © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3335–3347, 2001
Reverse atom transfer radical polymerization of vinyl monomers with Fe[SC(S)NEt2]3 alone as the catalyst
Authors: Qin Dong‐Qi , Qin Shu‐Hui , Qiu Kun‐Yuan 
Published: August 2002

AbstractThe living radical polymerization of methyl methacrylate and styrene was successfully carried out with diethyl 2,3‐dicyano‐2,3‐diphenylsuccinate (DCDPS)/ferric tri(diethyldithiocarbamate) as a novel reverse atom transfer radical polymerization initiation system in which DCDPS was a hexa‐substituted ethane‐type thermal iniferter, DC was a diethyldithiocarbamate group, and no additional ligands such as nitrogen‐ or phosphine‐based compounds were required. The bulk polymerization of methyl methacrylate was carried out at 95 °C, and that of styrene was carried out at 120 °C. Poly(methyl methacrylate) and polystyrene (PSt) with high molecular weights and quite narrow molecular weight distributions (as low as 1.09 for PSt) were obtained. 1H NMR spectroscopy revealed the presence of an α‐(carbethoxycyanophenyl)methyl group from the initiator and an ω‐DC group from the catalyst in the obtained polymers. Various chain‐extension reactions under UV light or thermal treatments were successfully conducted to prove the presence and efficient reinitiating of the ω‐DC group. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3464–3473, 2001