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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 23 (1990), S. 502-509 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of polymer research 3 (1996), S. 89-95 
    ISSN: 1572-8935
    Keywords: Thermotropic ; Poly(ester-amide)s ; Direct polycondensation ; DPCP ; Nematic
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Thermotropic Poly(ester-amide)s containing triethyleneglycol bis(4-carboxyphenyl) ether (PEG3), o-Tolidine (OT) and various aromatic diols such as hydroquinone (HQ) and 4,4′-biphenol (BP) were synthesized by direct polycondensation with DPCP (diphenyl chlorophosphate) as direct condensation agent in the presence of pyridine and LiCl. The polymer structures were characterized by infrared spectroscopy and elemental analysis. The influence of structure, substituents and contents of various aromatic diols on the phase transitions were studied by Differential Scanning Calorimetry (DSC) and Polarized Optical Microscopy. These revealed that the structure and substituents of diols affected the mesophase while most of the synthesized polymers exhibit nematic mesophase. Addition of HQ decreased the melting temperature of the polymers, but, in contrast to others diols, did not affect thermal resistance.
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  • 3
    ISSN: 1572-8935
    Keywords: Block copolyetheresters ; Poly(trimethylene 2,6-naphthalenedicarboxylate) ; Segments ; Thermal transitions ; X-ray diffraction ; Thermal stimulated current
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Block copolyetheresters with hard segments of poly(trimethylene 2,6-naphthalenedicarboxylate) and soft segments of poly(tetramethylene oxide) were prepared by melt polycondensation of dimethyl 2,6-naphthalenedicarboxylate, 1,3-propanediol and poly(tetramethylene ether)glycol (PTMEG) of molecular weights of 650, 1000 and 2000. The block copolyetheresters were characterized by FTIR, 1H NMR, DSC, X-ray diffraction, TSC (thermal stimulated current), DMA and TGA. It was found that the thermal transitions were dependent on the composition. As the charge molar ratio of PTMEG to dimethyl 2,6-naphthalenedicarboxylate, x, increased, the Tm and ΔHm of the polyester segments decreased, which has been also confirmed by the X-ray diffraction data. The polyether segments of the block copolyetheresters derived from PTMEG2000 could crystallize after cooling, but those of the block copolyetheresters derived from PTMEG1000 and PTMEG650 could not crystallize. The DSC, TSC and DMA results show consistent Tg data of the polyether segments. Based on the shift in Tg of the polyether segments, the amorphous parts of the polyether segments and the amorphous parts of the polyester segments were immiscible for the block copolyetheresters derived from PTMEG2000, but became partially miscible for the block copolyetheresters derived from PTMEG1000 and PTMEG650. The TGA results indicated that composition had little effect on thermal degradation under nitrogen.
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  • 4
    ISSN: 1572-8935
    Keywords: Surface reconstruction ; Adhesion ; Silicone ; Polyurethane ; FTIR-ATR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A new class of hydroxyl-functionalized polydimethylsiloxane-block-hydroxyl graft acrylate prepolymer (PDMS-b-HGAP) copolymers was synthesized. The copolymers were characterized using Fourier transform infrared spectroscopy as well as 1H and 13C nuclear magnetic resonance spectroscopy. The hydroxyl groups of the HGAP were reacted with the chlorine terminal in the PDMS to yield a triblock copolymer consisting of two segments of PDMS linked to a HGAP segment. The induced surface reconstruction of silicone rubber (SR)by blending polysiloxane reactants with bifunctional PDMS-b-HGAP copolymers and curing using mold materials having high critical surface tension such as polyethyleneterephthalate was attempted to improve the adhesion between chemically-inert SR and polyurethane (PU). Surface characterization using Foruier transform infrared-attenuated total reflectance indicated that the surface of the SR was enriched with HGAP. The increased content of surface HGAP was suggested to account for the improved adhesion between SR and PU.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1572-8935
    Keywords: Polyarylate ; Liquid crystal polymer ; Naphthalene dicarboxylic acid ; Kinky monomer ; Anisotropy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A series of copolyarylates primarily based upon 2,6-naphthalene dicarboxylic acid, hydroxybenzoic acid and 4,4′-biphenol were prepared by slurry-melt polymerization with Santotherm 66 as a heat exchange medium. The frequently used kinky monomer, resorcinol or isophthalic acid, was introduced into these copolyarylates to modify the chemical strcture. The relationship of the thermal behavior and the crystalline structures for these copolymers was studied by means of DSC and wide angle X-rays diffraction. The amount of mcorporated kinky modifier was found to produce a significant effect on the liquid crystalline phase and the melting temperature of the copolyarylates. All of these liquid crystal polymers exhibited nematic textures; shreaded and/or Schlieren type, depending upon the incorporated kinky monomer. The liquid crystal polymers modified by isophthalic acid (up to 40 mole % of 2,6-naphthalene dicarboxylic acid replaced by isophthalic acid) possessed shreaded texture however high the temperatures of the polymer melts were. The liquid crystal polymers modified by resorcinol (60 to 100 mole % of 4, 4′-biphenol replaced by resorcinol), however, would have two types of nematic textures: the shreaded texture occurred when the temperature of the polymer melt was between the melting temperature and the anisotropic transition temperature; the Schlieren texture existed when the temperature of the polymer melt was high above the anisotropic transition temperature. The Schlieren texture formed only when a liquid crystal polymer revealed good flowability and lower rigidity. The polydomain concepts could be utilized to explain the observed textures of these copolyarylates clearly.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of polymer research 7 (2000), S. 115-123 
    ISSN: 1572-8935
    Keywords: Latex ; Polymeric surfactant ; Alkali soluble resin ; Emulsion polymerization ; Retarding effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract In this work, alkali soluble resin (ASR) was evaluated as a surfactant in the emulsion polymerization of butyl methacrylate (BMA). Kinetic analysis indicated that the ASR surfactant retarded the reaction rate and reduced the average number of radicals per latex particle. Since the particle nucleation period proceeds until the disappearance of droplets, Interval II does not exist in this system. Experimental results show that the particle number depends on the 0.31 and 0.51 powers of the ASR and KPS concentration, respectively. The particle size distribution of the latex becomes broad with the increase of the ASR concentration in the emulsion polymerization. This phenomenon explains why the period of the particle nucleation is proportional to the ASR concentration used in the reaction.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 196 (1995), S. 629-643 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Main-chain thermotropic polyesters containing naphthalene rings and flexible spacers with 2 ≤ n ≤ 10 methylene groups were prepared in this study. Their thermotropic properties were investigated by means of differential scanning calorimetry (DSC) and polarized optical microscopy (POM). The nematic mesophase dominates the anisotropy of the prepared polymers except for the polymers with n = 7 and n = 9. Moreover, the nematic domain size depends upon the number n. On the other hand, the naphthalene ring in the mesogen has a strong effect on the mesomorphic properties of the prepared polyesters. The polymers with n = 7 and n = 9 exhibit cooling rate-dependent anisotropic behavior of nematic and smectic phases. The crystallization for the investigated polymers is strongly influenced by the anisotropic behavior. The kinetics of crystallization at higher temperatures does not satisfy the Ozawa theory, while it does at lower temperatures. Nucleation begins to occur in the nematic shreads and the crystal growth proceeds toward liquid-crystalline domains from the observation by POM. Thus, the Avrami exponent a is dependent upon the polymethylene spacer with n being even or odd and high or low. In addition, the parameters of crystallization obtained from DSC and X-ray diffraction were consistent with the results of non-isothermal crystallization kinetics and the observation by POM.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 9 (1988), S. 27-35 
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A method including the effects of fiber length and orientation distribution to predict elastic moduli of short fiber reinforced thermplastics (FRTP) is presented. The fiber length distribution in FRTP has an asymmetric character with a tail at the long fiber end. Statistical distribution functions such as Weibull or log-normal can be used to represent this kind of distribution. Orientation distribution of fibers in FRTP can be characterized by a single parameter exponential function, \documentclass{article}\pagestyle{empty}\begin{document}$F(\theta) = \frac{{1 - \lambda \theta }}{{1 - e^{ - \frac{\P}{2}\lambda } }}$\end{document}. A large λ indicates a highly oriented material whereas small λ represents a quasi-isotropic material. As fiber length and orientation distribution functions have been characterized, the elastic moduli of FRTP can be predicted. First, the mean elastic moduli of unidirectional plies are predicted through the fiber length distribution. Then the stacking sequence of laminate is assumed to be as the fiber orientation distribution of FRTP, and the overall elastic moduli of FRTP are estimated based on the laminate-plate method.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 3605-3616 
    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: Random copolymers of methyl methacrylate/n-butyl acrylate with a BA content of 0-50% and M̄v = 0.16-4.04 × 106 were synthesized and evaluated as a processing aid (PA) for poly(vinyl chloride) (PVC). Their effects on the processability and properties of PVC were investigated with respect to the composition, molecular weight, and the amount of the copolymer added. It was found that the fusion rate of PVC could be improved (i) by increasing the amount of the copolymer used, (ii) by increasing the butyl acrylate content in the copolymer, and (iii) by lowering the molecular weight of the copolymer. The effect of molecular weight, composition, and amount of copolymer on the ultimate mechanical properties of PVC was investigated. The presence of copolymer did not affect the impact strength. However, the tensile strength and elongation at break were improved, particularly at high temperature (125°C). It was also found that the “plate out” phenomenon of PVC could be significantly reduced in the presence of the processing aid.
    Additional Material: 14 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 6317-6327 
    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: n-Butylacrylate/acrylic acid (nBA/AA) copolymers were synthesized and used to modify epoxy resin (DGEBA) cured with dicyandiamide (DICY). The precuring reaction between nBA/AA copolymer and DGEBA, the curing cycle of DGEBA, and the effects of DICY and aluminum powder upon the adhesive strengths of modified DGEBA were studied. It was found that the optimum DICY/DGEBA ratio was 6 g/100 g, and lap shear strength and T-peel strength increased with increasing amount of aluminum powder. The curing cycle for modified DGEBA was determined to be 1 h at 177°C.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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