bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polyamides incorporating furan moieties: 4. Synthesis, characterisation and properties of a homologous series
Authors: Gharbi Souhir , Afli Aljia , Gharbi Rachid El , Gandini Alessandro 
Published: August 2002

AbstractInterfacial polycondensation of 2,2′‐bis[2‐(5‐chloroformylfuryl)]propane with various diamines gave high yields of a novel series of furanic polyamides with high inherent viscosities. The properties of these polymers (Tg, surface energy, crystallinity, thermal stability) were assessed and examined in terms of the role of the specific structure of the bridging group borne by the diamines. Only three polyamides were partially crystalline, whereas all the others were amorphous. Thermogravimetric analysis revealed that thermal decomposition began above 300 °C in all instances.© 2001 Society of Chemical Industry
Comparative studies on the flocculation characteristics of polyacrylamide grafted guar gum and hydroxypropyl guar gum
Authors: Nayak B R , Singh R P 
Published: August 2002

AbstractThe synthesis of two polysaccharide‐based graft copolymers with acrylamide, guar gum grafted polyacrylamide (GG‐g‐PAM) and hydroxypropyl guar gum grafted polyacrylamide (HPG‐g‐PAM) is described. The graft copolymers have been characterized by viscometry, infrared spectroscopy and thermal analysis. The flocculation characteristics of the graft copolymers have been studied in kaolin, iron ore, and silica suspensions. For the base polysaccharides guar gum (GG) and hydroxypropyl guar gum (HPG), it is observed that GG exhibits better performance than HPG in all three suspensions. For the graft copolymers, HPG‐g‐PAM shows better performance than GG‐g‐PAM. The flocculation characteristics of the best performing graft copolymer (HPG‐g‐PAM) are compared with various commercially available flocculants in the three suspensions mentioned above.© 2001 Society of Chemical Industry
Influence of the polarity of ethylene–vinyl acetate copolymers on the morphology and mechanical properties of their uncompatibilised blends with polystyrene
Authors: Tang L W , Tam K C , Yue C Y , Hu X , Lam Y C , Li L 
Published: August 2002

AbstractRubber‐toughened polystyrene has been extensively studied and is a well‐established technology. However, the use of thermoplastic elastomers to toughen polystyrene (PS) is new and has the potential for further investigations. In the present study, three EVAs (ethylene–vinyl acetate copolymers) with identical melt flow indices (MFIs), of ∼2.5 dgmin−1, but different vinyl acetate (VA) contents, of 9.3 wt% (EVA760), 18.0 wt% (EVA460) and 28.0 wt% (EVA265), were melt blended with PS at 180 °C, and various ASTM test pieces were injection moulded at 200 °C. The polarity of the dispersed phase (ie EVA), has a significant effect on the mechanical properties of the blends. Both mechanical and rheological studies reveal that the uncompatibilised PS/EVA265 blends exhibit some degree of compatibility when the amount of EVA265 is lower than 30 wt%. These results indicate that EVA265 with the highest VA content is the most effective impact modifier for PS. The results clearly show that increasing the VA content in EVA increases the polarity of the dispersed phase, approaching that of the matrix (ie PS) and subsequently improving the compatibility between the two phases in terms of interfacial adhesion.© 2002 Society of Chemical Industry
GaAs solar cells grown on Si substrates for space use
Authors: Yamaguchi Masafumi , Ohmachi Yoshiro , Oh'hara Takahiko , Kadota Yoshiaki , Imaizumi Mitsuru , Matsuda Sumio 
Published: August 2002

AbstractGaAs single‐junction and InGaP/GaAs multi‐junction thin‐film solar cells fabricated on Si substrates have great potential for high‐efficiency, low‐cost, lightweight and large‐area space solar cells. Heteroepitaxy of GaAs thin films on Si substrates has been examined and high‐efficiency GaAs thin‐film solar cells with total‐area efficiencies of 18·3% at AM0 and 20·0% at AM 1·5 on Si substrates (GaAs‐on‐Si solar cells) have been fabricated. In addition, 1‐MeV electron irradiation damage to GaAs‐on‐Si cells has been studied. The GaAs‐on‐Si cells are found to show higher end‐of‐life efficiency than the conventional GaAs cells fabricated on GaAs substrates (GaAs‐ on‐GaAs cells) under high‐fluence 1‐MeV electron irradiation of more than 1 × 1015 cm−2. The first space flight to make use of them has been carried out. Forty‐eight 2 × 2 cm GaAs‐on‐Si cells with an average AM0 total‐area efficiency of 16·9% have been evaluated in the Engineering Test Satellite No.6 (ETS‐VI). The GaAs‐on‐Si cells have been demonstrated to be more radiation‐resistant in space than GaAs‐on‐GaAs cells and 50, 100 and 200‐μm‐thick Si cells. These results show that the GaAs‐on‐Si single‐junction and InGaP/GaAs‐on‐Si multi‐junction cells have great potential for space applications. Copyright © 2001 John Wiley & Sons, Ltd.
Purification of metallurgical‐grade silicon up to solar grade
Authors: Yuge N. , Abe M. , Hanazawa K. , Baba H. , Nakamura N. , Kato Y. , Sakaguchi Y. , Hiwasa S. , Aratani F. 
Published: August 2002

AbstractAn estimate has been made of the feasibility of a metallurgical purification process, the NEDO (New Energy and Industrial Technology Development Organization) melt‐purification process, for manufacturing solar‐grade silicon from metallurgical‐grade silicon. Equipment has been developed to pilot manufacturing plant scale. The system comprises an electron‐beam furnace for phosphorus removal and a plasma furnace for boron removal. Each furnace has a mold for directional solidification to remove metallic impurities. The concentration of each impurity in the silicon ingot purified through the whole process satisfied the solar‐grade level. The Solar‐grade silicon produced showed p‐type polarity and resistivity within the range 0·5–1·5 Ω cm. Copyright © 2001 John Wiley & Sons, Ltd.
Crystalline silicon manufacturing progress
Authors: Jester Theresa L. 
Published: August 2002

AbstractThe increasing demand for renewable forms of energy is making photovoltaic products an important part of the energy supply future. The costs of producing photovoltaic modules have been significantly reduced during the last 10 years as manufacturing costs per watt have dropped from over $6 per peak watt to less than half of that value now. This paper summarizes progress in several aspects of photovoltaic manufacturing which have contributed to this reduction. Crystal growth improvements, both in yield and machine design, have reduced the energy consumption by a factor of 3 and improved silicon utilization by 40%. Wafer slicing process changes have resulted in 66% more wafers being produced for a given amount of silicon. Cell production improvements in both automation and improved efficiency have reduced the labor cost contribution by 40% per watt. Larger modules and better materials have added another 10% reduction in the cost to produce photovoltaics. These improvements have contributed to a better energy payback time, reducing it from over 5 years to approximately 3. Reductions in cost and improvements in energy efficiency have made photovoltaic products a commercially viable alternate energy source. Copyright © 2002 John Wiley & Sons, Ltd.
Crystalline silicon feedstock for solar cells
Authors: Aulich Hubert A. , Schulze Friedrich‐Wilhelm 
Published: August 2002

AbstractThe generation of electricity with solar cells is considered to be one of the key technologies of the new century. Over the past ten years the photovoltaic (PV) industry has grown by more than a factor of five to approximately 200 MWp in the year 2000. This impressive growth is mainly based on solar cells made from crystalline silicon. One of the key factors for this growth has been the supply of economically priced silicon from the semiconductor industry. This paper gives an overview on the current silicon feedstock supply and outlines a supply and demand scenario for the next five years. The importance of better silicon utilization per Wp module power through thinner Si wafers and higher solar cell efficiency is stressed. The impact of a growing thin‐film technology on the silicon feedstock demand is considered as well. Copyright © 2002 John Wiley & Sons, Ltd.
Organosoluble and transparent polyimides derived from alicyclic dianhydride and aromatic diamines
Authors: Liu J. G. , He M. H. , Zhou H. W. , Qian Z. G. , Wang F. S. , Yang S. Y. 
Published: August 2002

AbstractOrganosoluble polyimides were synthesized with the alicyclic dianhydride 1,8‐dimethylbicyclo[2,2,2]oct‐7‐ene‐2,3,5,6‐tetracarboxylic dianhydride and aromatic diamines. The polyimides possessed good solubility both in strong dipolar solvents and in common solvents; the thermal decomposition temperature of the polyimides exceeded 420 °C. Strong and flexible films of the polyimides, with the cutoff of ultraviolet–visible absorption lower than 310–320 nm, exhibited good features as the alignment layers for nematic liquid crystals with pretilt angles of 1.5–2.9°. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 110–119, 2002
Organosoluble and light‐colored fluorinated polyimides from 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)biphenyl and aromatic dianhydrides
Authors: Yang Chin‐Ping , Hsiao Sheng‐Huei , Hsu Mao‐Feng 
Published: August 2002

AbstractA novel fluorinated diamine monomer based on 4,4′‐biphenol was synthesized via a straightforward, high‐yielding two‐step procedure. 4,4′‐Biphenol was reacted with 2‐chloro‐5‐nitrobenzotrifluoride in the presence of potassium carbonate to yield the intermediate dinitro compound, which was subsequently reduced to afford the fluorinated diamine, 4,4′‐bis(4‐amino‐3‐trifluoromethylphenoxy)biphenyl. A series of organosoluble fluorinated polyimides were prepared from the diamine with various aromatic dianhydrides via a conventional two‐step thermal imidization method. All polyimides were soluble in strong dipolar solvents such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide. The polyimides showed excellent thermal and thermooxidative stability and good mechanical properties. No significant weight loss was observed below a temperature of 520 °C in nitrogen or in air, and the glass‐transition temperatures ranged from 247 to 313 °C. Low dielectric constants (2.57–3.65 at 10 kHz), low moisture absorption (0.1–0.7 wt %), and low color intensity were also observed. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 524–534, 2002; DOI 10.1002/pola.10113
Effect of the organophosphate structure on the physical and flame‐retardant properties of an epoxy resin
Authors: Shieh Jeng‐Yueh , Wang Chun‐Shan 
Published: August 2002

Abstract2‐(6‐Oxido‐6H‐dibenzo〈c,e〉〈1,2〉oxa‐phosphorin‐6‐yl)1,4‐benzenediol (ODOPB) and bis(3‐dihydroxyphenyl) phenyl phosphate (BHPP) were successfully synthesized and used as reactive flame retardants in o‐cresol formaldehyde novolac epoxy resin. Because of the rigid, cyclic, side‐chain structure of ODOPB, the resultant phosphorus‐containing epoxy resin exhibited a higher glass‐transition temperature, better flame retardancy, higher modulus, and greater thermal stability than the regular bromine‐containing tetrabromobisphenol A epoxy resin and the linear, main‐chain, phosphorus‐containing BHPP epoxy resin. A UL‐94VO rating was achieved with a phosphorus content as low as 1.1% with ODOPB (comparable to a bromine content of 12% and a phosphorus content of 2.2% with BHPP) in the cured resins, and no fumes or toxic gas emissions were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 369–378, 2002
Synthesis and characterization of conducting poly(aniline‐co‐o‐aminophenethyl alcohol)s
Authors: Baek Sungsik , Ree Jason J. , Ree Moonhor 
Published: August 2002

AbstractPoly(o‐aminophenethyl alcohol) and its copolymers containing the aniline unit were synthesized in aqueous hydrochloric acid medium by chemical oxidative polymerization. The chemical composition of these novel polymers was determined spectroscopically, and their viscosities were measured. These polymers exhibit good solubility in organic solvents that is attributed mainly to the polar hydroxyethyl side groups. Their structures (chain conformation and morphological structure) and properties (conductivity, electrochemical characteristics, glass transition, and degradation behavior) were characterized and then interpreted on the basis of the chemical composition along with the electronic and steric hindrance effects associated with the hydroxyethyl side group. Overall, the side group has a significant effect on the polymerization and influences the structure, chain conformation, and properties of the resultant polymer. The poly(aniline‐co‐o‐aminophenethyl alcohol)s containing 20–40 mol % o‐aminophenethyl alcohol units are potential conducting materials for microelectronic and electromagnetic shielding applications because they are easier to process than polyaniline but retain its beneficial properties. These polymers can also be used as a functional conducting polymer intermediate owing to the reactivity of the side group. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 983–994, 2002
Preparation of poly(N‐ethyl methacrylamide) particles via an emulsion/precipitation process: The role of the crosslinker
Authors: Hazot P. , Chapel J. P. , Pichot C. , Elaissari A. , Delair T. 
Published: August 2002

AbstractMonodisperse, thermosensitive poly(N‐ethyl methacrylamide) microgel particles were prepared by the batch precipitation/emulsion polymerization of water‐soluble N‐ethyl methacrylamide and the hydrophobic crosslinker ethylene glycol dimethacrylate initiated by potassium persulfate. Particular attention was paid to the effect of the crosslinker agent on the polymerization process (kinetics, conversion, and water‐soluble oligomer content). Particles were characterized in terms of their size distribution and swelling capacity. A polymerization mechanism for the water‐soluble monomer and non‐water‐soluble crosslinker is proposed and discussed on the basis of a combination of both emulsion and precipitation polymerization processes. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1808–1817, 2002
Atom transfer radical homo‐ and block copolymerization of methyl 1‐bicyclobutanecarboxylate
Authors: Chen Xiao‐Ping , Padias Anne Buyle , Hall H. K. 
Published: August 2002

AbstractA non‐olefinic monomer, methyl 1‐bicyclobutanecarboxylate (MBC), was successfully polymerized by the controlled/“living” atom transfer radical polymerization (ATRP) technique, resulting in a well‐defined homopolymer, PMBC, with only cyclobutane ring units in the polymer chain. An AB block copolymer poly(methyl 1‐bicyclobutanecarboxylate)‐b‐polystyrene (PMBC‐b‐PS), having an all‐ring unit segment, was also synthesized with narrow polydispersity and designed number‐average molecular weight in addition to precise end groups. The 1H NMR spectra, glass‐transition temperature, and thermal stability of PMBC, PMBC‐b‐PS, and PS‐b‐PMBC were investigated. The experimental results showed that the cyclobutane rings in the two block polymers improved their thermal stability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1929–1936, 2002
Polar, functionalized diene‐based materials. V. Free‐radical polymerization of 2‐[(N‐benzyl‐n‐methylamino)methyl]‐1,3‐butadiene and copolymerization with styrene
Authors: Wu Lifen , Sheares Valerie V. 
Published: August 2002

Abstract2‐[(N‐Benzyl‐N‐methylamino)methyl]‐1,3‐butadiene (BMAMBD), the first asymmetric tertiary amino‐containing diene‐based monomer, was synthesized by sulfone chemistry and a nickel‐catalyzed Grignard coupling reaction in high purity and good yield. The bulk and solution free‐radical polymerizations of this monomer were studied. Traditional bulk free‐radical polymerization kinetics were observed, giving polymers with 〈Mn〉 values of 21 × 103 to 48 × 103 g/mol (where Mn is the number‐average molecular weight) and polydispersity indices near 1.5. In solution polymerization, polymers with higher molecular weights were obtained in cyclohexane than in tetrahydrofuran (THF) because of the higher chain transfer to the solvent. The chain‐transfer constants calculated for cyclohexane and THF were 1.97 × 10−3 and 5.77 × 10−3, respectively. To further tailor polymer properties, we also completed copolymerization studies with styrene. Kinetic studies showed that BMAMBD incorporated into the polymer chain at a faster rate than styrene. With the Mayo–Lewis equation, the monomer reactivity ratios of BMAMBD and styrene at 75 °C were determined to be 2.6 ± 0.3 and 0.28 ± 0.02, respectively. Altering the composition of BMAMBD in the copolymer from 17 to 93% caused the glass‐transition temperature of the resulting copolymer to decrease from 64 to −7 °C. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3227–3238, 2001
Role of the in‐plane orientation of polyimide films in graphitization
Authors: Takeichi Tsutomu , Zuo Min , Hasegawa Masatoshi 
Published: August 2002

AbstractPoly(amide acid) labeled with perylenetetracarboxydiimide (PEDI) was prepared from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA), p‐phenylenediamine (PDA), and diamino‐PEDI. Poly(amide acid) was then reacted with sodium hydride and various kinds of alkyl iodides for transformation into various poly(amide ester)s. The cast films were imidized while fixed on glass substrates to give BPDA/PDA polyimide films. The degree of in‐plane molecular orientation (f) of the polyimides and their precursors, poly(amide acid) and poly(amide ester)s, were determined via measurements of the visible dichroic absorption at an incidence angle for a rodlike dye (PEDI) bound to the main chain. All precursor films showed relatively low degrees of in‐plane orientation. After imidization of the precursors fixed on glasses, however, striking spontaneous in‐plane orientation behavior was observed. The f value for polyimide film from a poly(amide acid) precursor was as high as 0.7–0.8. The f value for polyimide film from a methyl ester precursor, however, was lowered to 0.4–0.5, but it increased with the increasing size of the alkyl groups. Good correlations of the in‐plane orientation of the polyimide films with the tensile modulus of the films and the in‐plane orientation of the graphitized films were observed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 3011–3019, 2001
Fatigue crack propagation mechanisms in poly(methyl methacrylate) by in situ observation with a scanning laser microscope
Authors: Ishiyama C. , Asai T. , Kobayashi M. , Shimojo M. , Higo Y. 
Published: August 2002

AbstractCrack propagation tests were performed on an amorphous polymer, poly(methyl methacrylate), to investigate fatigue crack propagation mechanisms. A scanning laser microscope with a newly developed tensile testing machine was used to observe in situ crack propagation in compact‐type specimens. A crack usually propagated within the craze located at the crack tip under both static and cyclic loading conditions. When a crack stably propagated into the craze under static loading conditions, bright bands composed of the broken craze were observed at the edges along the crack wakes. However, there were successive ridges and valleys in place of bright bands along the crack wakes under cyclic loading conditions. When stable fatigue cracks were propagated at the loading half‐cycle in each cycle, new craze fragments appeared that were similar to the bright bands under static loading. However, the thickness of these fragments decreased in the following loading cycle, and a new valley was formed. This suggested that the valleys were formed by the contact between the fracture surfaces near the crack tip during unloading. Fatigue crack propagation is thought to be due to fibrils weakened by crack closure between fracture surfaces. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 3103–3113, 2001
Structural characteristics and moisture sorption behavior of nylon‐6/clay hybrid films
Authors: Murase Shigemitsu , Inoue Atsushi , Miyashita Yoshiharu , Kimura Noritaka , Nishio Yoshiyuki 
Published: August 2002

AbstractThe structure of nylon‐6 hybrids with synthetic or natural clays was investigated for melt‐pressed films with Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, and differential scanning calorimetry in comparison with the nylon‐6 homopolymer. In contrast to the development of familiar α‐form crystals in plain nylon‐6 film, the hybrid films produced γ‐form crystals when nylon‐6 was conjugated with synthetic mica, whereas the hybridization with natural montmorillonite gave rise to both α‐ and γ‐crystalline modifications. The degree of crystallinity of the nylon‐6 hybrid with synthetic mica was the highest of the three series. Moisture sorption isotherms obtained for these nylon‐6‐based films were all typically sigmoid‐shaped, although the prevalence of a higher crystallinity in the hybrid samples lowered the degree of moisture regain. The sorption behavior was analyzed well in terms of the parameters of a Brunauer–Emmett–Teller multiplayer adsorption model and a Flory–Huggins treatment. It was also observed that the cluster formation of the water adsorbed into the nylon‐6 matrix tended to be restricted by the hybridization with clay. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 479–487, 2002; DOI 10.1002/polb.10106
Structures induced by irradiation of femto‐second laser pulse in polymeric materials
Authors: Katayama Shigeru , Horiike Mika , Hirao Kazuyuki , Tsutsumi Naoto 
Published: August 2002

AbstractWe investigated the structures induced by irradiation of near‐infrared femto‐second laser pulse in various polymer materials; olefin gel, acrylic adhesive, poly(ether sulphone) (PES), poly(methyl methacrylate) (PMMA), polycarbonate (PC), and block copolymers of methyl‐methacrylate and ethyl acrylate‐butyl acrylate. Line irradiation that was performed by scanning laser spots in polymer bulk formed volcano‐like upheaval structures on the surfaces of PES, PMMA, and PC, which have relatively high glass‐transition temperatures (Tg's); on the other hand, cave or channel structures on the surfaces of olefin gel and acrylic adhesive have low Tg's. For the block copolymers containing both low and high Tg's, aggregation of the submicron scale deposit was induced in the polymer bulk. The submicron scale deposit may be reproduced structures after photodecomposition or photocrosslinking of polymer‐chain components induced by multiphoton excitation with femto‐second laser irradiation. This deposit aggregation with a stripelike structure had different optical properties from the un‐irradiated region. These structures induced by irradiation of femto‐second laser pulse might be applicable for optical devices such as diffraction grating and optical guide. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 537–544, 2002; DOI 10.1002/polb.10111