ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 11
    Electronic Resource
    Electronic Resource
    The curing of dicyanate ester liquid crystalline thermosetsLecture presented at the “International Symposium on Advanced Network-Polymers, Kansai University” (ISANKU), at Kansai University, Suita, Osaka, Japan, on December 5-6, 1995. (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 59-66 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The attractive physical properties of cyanate ester resins make these materials an important class of high-performance polymer thermosets for applications such as electro-optic coatings and thin film dielectrics. Triazine networks have been used as insulating materials for over 25 years; however, in order to meet future requirements such materials must exhibit appropriate glass transition temperatures, high thermal stability, high moduli, good adhesion at elevated temperatures, low dielectric losses, and a low coefficient of thermal expansion (CTE). With our approach to thermoset design and processing we are able to directly control their mechanical and physical properties by curing new liquid crystalline cyanate ester resins in electric fields. Combining new LC materials with non-LC cyanate monomers leads to a variety of novel ordered network structures and is a convenient method for modifying and controlling their chemical and physical properties. Studies of the new LC thermosets and their mixtures with non-LC materials will be described.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052400105
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 12
    Electronic Resource
    Electronic Resource
    Smectic networks obtained from twin LC epoxy monomers - mechanical deformation of the smectic networks (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 31-38 
    Details
    ISSN: 0887-6266
    Keywords: liquid crystals ; thermosets ; smectic epoxy ; nematic ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Deformation experiments were carried out for densely crosslinked smectic-like networks obtained from diepoxy monomers with twin mesogen architecture. For the initially unoriented smectic networks, the network could be aligned up to an orientation parameter of 0.35 by applying 8 MPa of external stress in the rubbery regime. X-ray diffraction measurements revealed that the deformed smectic network possesses both smectic-A like and smectic-C like structure. It is thought that after extension domains initially oriented parallel to the external stress displayed a smectic-A-like structure, whereas domains initially tilted with respect to the tensile direction showed a stress-induced smectic-C like structure. A smectic network oriented under a.c. electric fields with an orientation parameter of 0.4 had a smectic-A like structure and possessed linear elasticity in the rubbery regime. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 31-38, 1998
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 13
    Electronic Resource
    Electronic Resource
    Flow-induced structure in a thermotropic liquid crystalline polymer as studied by SANS (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 3017-3023 
    Details
    ISSN: 0887-6266
    Keywords: liquid crystalline polymer ; shear alignment ; thermotropic polymer ; small-angle neutron scattering ; flow-induced structure ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Small-angle neutron scattering is utilized to determine the flow induced alignment of a model thermotropic liquid crystalline polymer (LCP) as a function of shear rate and temperature. The results demonstrate that the flow-induced structures in thermotropic liquid crystalline polymers have similarities and differences to those in lyotropic liquid crystalline polymer solutions. The shear rate dependence of the alignment shows that the flow-induced alignment correlates very well to the viscosity behavior of the LCP in the shear thinning regime, while temperature variation results in a change in the extent of alignment within the nematic phase. Relaxation results also demonstrate that the flow-induced alignment remains essentially unchanged for up to an hour after the shear field has been removed. Last, there exists a regime at low shear rate and low temperature where alignment of the LCP molecule perpendicular to the applied shear flow is stable. These results provide important experimental evidence of the molecular level changes that occur in a thermotropic liquid crystalline polymer during flow, which can be utilized to develop theoretical models and more efficiently process thermotropic polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 3017-3023, 1998
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 14
    Electronic Resource
    Electronic Resource
    Liquid crystalline networks from 1,4-benzenedicarboxylic acid bis(4-cyanatomethylphenyl) ester (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 2957-2970 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The phase behaviour and curing reaction of 1,4-benzenedicarboxylic acid bis(4-cyanatomethylphenyl) ester (LC dicyanate) as well as the mechanical properties of the LC network were examined. The overall reaction kinetics were found to be first order with an activation energy of 67.5 kJ/mol similar to many conventional dicyanate monomers. Gelation was detected by viscoelastic measurements and occurred at a conversion of ≈0.5. These results suggest that the topology of the network formed in the LC dicyanate system was the same as non-LC dicyanates such as 2,2-bis(cyanatophenyl)propane. The onset of the mesophase was found to start at a conversion of ≈0.06 and end at a conversion of ≈0.20, independent of the curing temperature (180-280°C). This observation indicates that small clusters comprising a small oligomer (mainly trimer) surrounded by 6-7 monomers dominate formation of the mesophase which possesses a clearing temperature above at least 280°C. Competition between liquid crystalline order and high crosslink density resulted in a large free volume in the glassy state. This large free volume strongly affects mechanical behavior as well as the glass transition temperature of the LC network.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1997.021980924
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 15
    Electronic Resource
    Electronic Resource
    Preparation and properties of mesomorphic oligo(oxalate)s (1982)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 3 (1982), S. 543-548 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1982.030030804
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 16
    Electronic Resource
    Electronic Resource
    Liquid crystal polymers, 13Part 12: cf. C. Ober, R. W. Lenz, G. Galli, E. Chiellini, Macromolecules, submitted. A smectic aromatic polyester with triad mesogenic groups and a polymethylene spacer in the main chain (1983)
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 4 (1983), S. 49-55 
    Details
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1983.030040201
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 17
    Electronic Resource
    Electronic Resource
    Liquid crystalline polymers, 8Part 7: B. W. Jo, R. W. Lenz, and J.-I. Jin, Makromol. Chem., Rapid Commun 3, 23 (1982).. Structurally ordered thermotropic polyesters of glycol ethers (1982)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 183 (1982), S. 2693-2708 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A series of polysters based on a triad aromatic ester mesogenic unit but containing different poly(alkylene oxide) flexible spacers in the main chain was prepared and its properties examined. The flexible spacers consisted of poly(alkylene oxide)s of varying lengths based on either oligomers of ethylene oxide or propylene oxide. The spacer types, lengths and distributions were found to strongly affect the mesophase and melting behaviors of the polymers. Polymers with spacers having more than 10 units were not liquid crystalline, whereas those of shorter length exhibited mesophase properties. The polymers containing spacers with two, three, or four oxyethylene units showed two mesophases, and the textures of their mesophases suggested that both smectic and nematic phases were formed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1982.021831108
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 18
    Electronic Resource
    Electronic Resource
    Synthesis and curing of novel LC twin epoxy monomers for liquid crystal thermosets (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 1291-1303 
    Details
    ISSN: 0887-624X
    Keywords: liquid crystalline epoxides ; ordered network ; thermosets ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This article describes the synthesis and characterization of new liquid crystalline thermosets having a twin structure. Nematic epoxy-terminated monomers based on a phenyl benzoate twin mesogen connected by an alkylene spacer were synthesized for these studies. In addition, an epoxy-terminated monomer based on a 1,4-bis(benzoyloxy)phenylene mesogen was synthesized to determine the effect of the position of the mesogen on the final network structure. The diepoxy monomer made with phenyl benzoate twin mesogens connected with an alkylene spacer formed a smectic-like network when cured with diamines. This smectic organization appeared even though the diepoxy monomer itself showed only a nematic mesophase over a narrow temperature range. The presence of crosslinks at both ends of the mesogens helped to retain a uniform spacing between crosslinking sites during the curing reaction, and aided formation of the smectic layer arrangement. The epoxy monomer possessing a 1,4-bis(benzoyloxy)phenylene mesogen and two epoxidized alkylene end groups on both sides of the mesogen formed a stable nematic mesophase. However, in contrast to the twin epoxies, the latter epoxy when reacted with diamines tended to produce a nematic-like network which was retained as the crosslinking reaction proceeded. © 1996 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 19
    Electronic Resource
    Electronic Resource
    The effect of temperature and initiator levels on the dispersion polymerization of polystyrene (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1395-1407 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Considerable interest has been generated recently by the preparation of large monodisperse polymer latices by a multistage swelling process. Dispersion polymerization in organic media has been shown to be an alternative route to the preparation of large monodisperse polymer colloids. The size of the resulting particles is known to be dependent on the polarity of the reaction medium. Several other factors are also extremely important in determining both the size and size distribution of the resulting particles. These include the temperature of the reaction and the level of initiator. The temperature affects both the rate of free radical formation and the thermodynamic properties of the polymerization system. It is shown that monodispersity can be achieved over a considerable range of temperatures provided that a particular level of initiator is used at a given temperature. It is also shown that higher levels of initiator at a particular temperature actually produced larger particles. Interestingly, the level of initiator was not found to significantly change the overall rate of polymerization.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250516
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 20
    Electronic Resource
    Electronic Resource
    Novel ceramic particle synthesis for optical applications: Dispersion polymerized preceramic polymers as size templates for fine ceramic powdersMany thanks to Duane Barber and Prof. Clifford Pollock for the fluorescence measurements. LLB is grateful to the National Science Foundation and Department of Education for fellowship support, as well as the Cornell Materials Science Center for use of facilities. (1995)
    Weinheim : Wiley-Blackwell
    Advanced Materials 7 (1995), S. 1009-1012 
    Details
    ISSN: 0935-9648
    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
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19950071207
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...