Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Thermotropic longitudinal PLCs

Among the several hundreds of PLCs reported in papers and patents, thermotropic longitudinal PLCs [1] comprise a very important category. Longitudinal PLCs, formerly called main-chain PLCs, are those whose backbones consist of rod-like mesogens connected parallel to the backbone. Most thermotropic longitudinal PLCs are aromatic LC... [Pg.101]

Morphology of thermotropic longitudinal PLCs Skin layer... [Pg.106]

The morphology and properties of injection molded thermotropic longitudinal PLC products are similar to those of extrudates, i.e., macroscopic skin/core structure, microscopic hierarchically layered and... [Pg.106]

Blundell [28] first demonstrated that the main features of crystallization for thermotropic longitudinal PLCs are (1) small crystallites ( 5 nm for quenched samples and about 10 nm across for annealed ones) (2) limited crystallinity (about 20% in wide angle X-ray diffraction (WAXD)) (3) low surface energy of the crystallites (4) little change of molecular conformation before and after melting and (5) low fusion entropy and enthalpy (sometimes no detectable endotherm on DSC thermograms). A model of small crystal size for extended chain polymers was proposed by Blundell [28]. [Pg.117]

Polymorphism is also common for thermotropic longitudinal PLCs. Two types of crystal lattice exhibit in these PLCs orthorhombic and... [Pg.119]

The characteristics of the crystallization behaviors of thermotropic longitudinal PLCs can be summarized as (1) small and imperfect lamellae about lO-lOOnm in size (2) limited crystallinity (3) an increase of lamellar thickness, improvement of lateral correlation and transformation of the lattice resulting from annealing and (4) formation of high-melting crystals in the partially molten state. [Pg.121]

This chapter deals exclusively with thermotropics (pure polymer systems). This review deals with longitudinal one-comb and network PLCs and blends of longitudinal PLCs and conventional flexible chain polymers (Figure 10.2). An excellent introduction to the subject including a presentation of definitions and classifications is given by Brostow [10]. It is important to emphasize that a given PLC at a given... [Pg.307]

It was later confirmed by Ide and Chung [119] that these observations were also valid for thermotropics. Small-diameter rods of a longitudinal PLC (a copolyester based on 2,6-hydroxynaphthoic acid, terephthalic acid and p-aminophenol) were annealed above its crystal melting temperature in the nematic state for different periods of time. The dependence of the Young modulus at room temperature on the... [Pg.325]

Class a, longitudinal liquid crystal polymers, earlier called main-chain polymers. A new name is necessary to distinguish them from the following classes jS and y and the subclasses (S, (R and Al. There are numerous examples of class a. We do not discuss them here in any detail since the entire Chapter 8 by MacDonald is devoted to thermotropic ones, while Chapter 6 by Northolt and Sikkema deals with lyotropic PLCs of the same class. Orientational and conformational order in longitudinal PLCs is discussed by Frangoise Lauprete in Section 3.1.3.1 would only like to note an account of the history of first polyesters in this class and of future perspectives by Jackson. ... [Pg.15]

See other pages where Thermotropic longitudinal PLCs is mentioned: [Pg.102]    [Pg.102]    [Pg.102]    [Pg.102]    [Pg.108]    [Pg.110]    [Pg.112]    [Pg.114]    [Pg.116]    [Pg.117]    [Pg.118]    [Pg.120]    [Pg.122]    [Pg.122]    [Pg.122]    [Pg.177]    [Pg.112]    [Pg.102]    [Pg.102]    [Pg.102]    [Pg.102]    [Pg.108]    [Pg.110]    [Pg.112]    [Pg.114]    [Pg.116]    [Pg.117]    [Pg.118]    [Pg.120]    [Pg.122]    [Pg.122]    [Pg.122]    [Pg.177]    [Pg.112]    [Pg.104]    [Pg.317]    [Pg.59]    [Pg.61]    [Pg.257]   
See also in sourсe #XX -- [ Pg.102 , Pg.158 , Pg.177 ]



SEARCH



Longitudinal PLCs

Thermotropism

© 2024 chempedia.info