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  • Polymer and Materials Science  (6)
  • Semiconductors II: surfaces, interfaces, microstructures, and related topics  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 1939-1947 
    ISSN: 0887-624X
    Keywords: polytetrahydrofuran ; acetylhexachloro-antimonate ; chain transfer ; THF ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the presence of acetic anhydride, the catalyst containing protons makes the polymerization complex.1,2 Thus, whether the living center, during the polymerization process of THF, transfers to the acetic anhydride is a difficult problem to answer. In this article, CH3COSbCl6 is used as the catalyst to avoid the interference of the protons. It is found that acetic anhydride is an effective chain transfer agent, by the experiment at different temperatures for two systems in the presence or absence of acetic anhydride, and by the comparison of kinetic behavior. In the system without acetic anhydride at the temperature of 7, 15, and 22°C, the propagation rate constants of THF, kp are 7.90, 14.23, and 23.35 10-3L/Mol.S, respectively. In the presence of acetic anhydride, kp are 1.51, 2.85, and 4.98 10-3L/Mol.S; and ktr are 2.04, 3.59, and 6.49 10-4L/Mol.S, respectively. © 1994 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 1301-1307 
    ISSN: 0887-624X
    Keywords: 1,4-dioxan-2-one ; trimethylene carbonate ; stannous octoate ; drug delivery system ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(1,4-dioxan-2-one-co-trimethylene carbonate), P(DON-co-TMC), copolymers with different compositions were synthesized by copolymerizations of 1,4-dioxan-2-one (DON) and trimethylene carbonate (TMC) at 120°C in the presence of Sn(Oct)2. Their structures and compositions were determined with FT-IR and 1H-NMR spectroscopies. The intrinsic viscosities of copolymers increased with the increase of the TMC fraction in feed. The DSC results of copolymers showed that the glass transition temperatures (Tgs) of copolymers are lower than those of homopolymers. Most copolymers are amorphous except for one with a high DON composition. The hydrophilicity of the copolymers is in proportion with the DON molar fraction in the copolymers. It was found that the Levonorgestrel (LNG) release rate is dependent of the composition and flexibility of polymer chains. The fastest one is the copolymer with nearly a equivalent fraction of DON to TMC. Among copolymers with other compositions, a higher DON fraction would be favorable to the release of LNG. All measurements demonstrate an almost constant release rate in the period of 1 month. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1301-1307, 1998
    Additional Material: 8 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 695-702 
    ISSN: 0887-624X
    Keywords: ABA-type block copolymers ; ring-opening polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ABA-type block copolymers of poly(trimethylene carbonate) with poly(ethylene glycol) (Mn 6820), PTMC-b-PEG-b-PTMC, were synthesized by the ring-opening polymerization of 1,3-dioxan-2-one (trimethylene carbonate) in the presence of poly-(ethylene glycol) with stannous octoate catalyst, and the copolymers with various compositions were obtained. The PTMC-b-PEG-b-PTMC copolymers were characterized with Fourier transform infrared and nuclear magnetic resonance spectroscopies. The intrinsic viscosities of resulting copolymers increased with the increase of 1,3-dioxan-2-one content in feed while the molar ratio of monomer over catalyst kept constant. It has been observed that the glass transition temperature (Tg) of the PTMC segments in copolymers, recorded from differential scanning calorimetry, was dependent on the composition of copolymers. The melting temperature (Tm) of PEG blocks in copolymer was lower than that of PEG polymer, and then disappeared as the length of PTMC blocks increased. The results of dynamic contact angle measurement clearly revealed that the hydrophilicity of resulting copolymers increased greatly with the increase of PEG content in copolymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 695-702, 1998
    Additional Material: 6 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 789-797 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Medium molecular weight, novel polyfunctional elastomers, namely epoxy groups on poly(n-butylacrylate) (ETPnBA) and carboxyl groups on poly(n-butylacrylate) (CTPnBA) were photosynthesized for evaluation as the toughening agents in epoxy resins. The effect of the functionality and kind of functional group of the elastomers upon the toughening of epoxy resins modified with these rubbery copolymers as a second phase was investigated by tensile tests, impact test, and electron microscopy. It was found that there exists an optimum functionality of elastomers for maximum impact resistance in epoxy groups (ETPnBA) and carboxyl groups (CTPnBA) copolymer-modified systems. Studies on morphology of the modified epoxy resin system indicated that the better toughening effects of multiple distribution of particle sizes. The aggregation of rubber particles occurring in carboxyl group CTPnBA modified epoxy resin caused a loss of toughness.
    Additional Material: 9 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 2587-2593 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Tribochemical reactions of PTFE with aluminum, silicon, and iron during rubbing were detected by ESCA. No apparent relationship between this chemical reaction of the fillers with the PTFE in the composite and the wear-reducing action of those fillers on the composite material was found.
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 60 (1996), S. 2339-2346 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Porous polydimethylsiloxane (PDMS) membranes with α-amylase or glucose oxidase activity were prepared by catalytic hydrosilylation cure of PDMS in the presence of the enzymewater solution. The pores in the membrane are the result of hydrogen foams, which are generated during the curing reaction. The enzyme reactions were examined in batch and permeation experiments by using glucose and starch solutions as substrates. For the permeation set-up, the reaction yields of the immobilized α -amylase increased as the permeation rate of the starch solution decreased. The Michaelis-Menten type of reaction kinetics for the immobilized enzyme indicated that the permeation system is effective for the diffusion through the solute of the matrix, as compared with the batch system. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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  • 7
    Publication Date: 2012-05-23
    Description: Author(s): Zhongrui Wang, HongYu Yu, Xuan Anh Tran, Zheng Fang, Jinghao Wang, and Haibin Su Transport measurements of both the dc and the low-frequency ac are performed on Pt/HfO 2− x /TiN resistive-switching memory cells at various temperatures. The conductance of the pristine cells has a power law ω S T N relationship with temperature and frequency. To account for the much larger conductance o... [Phys. Rev. B 85, 195322] Published Tue May 22, 2012
    Keywords: Semiconductors II: surfaces, interfaces, microstructures, and related topics
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
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  • 8
    Publication Date: 2018-10-10
    Description: Author(s): Feng Wei, Chieh-Wen Liu, Da Li, Chun-Yang Wang, Hong-Rui Zhang, Ji-Rong Sun, Xuan P. A. Gao, Song Ma, and Zhidong Zhang The tunability of topological surface states and the controllable opening of the Dirac gap are two keys for the study of topological crystalline insulators (TCIs). By constructing PbTe/SnTe heterostructures, we discover giant linear magnetoresistance (GLMR) ( 2150 % under a magnetic field of 14 T at 2... [Phys. Rev. B 98, 161301(R)] Published Tue Oct 09, 2018
    Keywords: Semiconductors II: surfaces, interfaces, microstructures, and related topics
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
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