Modification of organic engineering materials for technological applications

It is reported about experiments for synthesis of novel reactive, thermotropic, liquid-crystalline polymers (LCPs) as well as about investigations concerning the use of these LCPs as a blend component for the production of modified polyamide and polyester fibres and their properties. These reactive LCPs are synthetically easy accessible polyester-imidanhydrides (PEIA) bearing lateral as well as terminal anhydride groups. The average number of anhydride groups is variable between 4 and 18. Molecular weights of 30 kg/mol up to 80 kg/mol could be obtained. During mixing of the reactive LC-PEIAs with polyamide 6 [PA 6] or poly(ethylene terephthalate) [PET] in an extruder under melting conditions both components evidently react within some few minutes to form graft-block-copolymers containing on their backbone chains lateral and terminal polyamide respectively polyester blocks. These quickly occurring modification reactions are the base for the industrial application in form of a continuously arrangeable "reactive blending-spinning-drawing"-process. Graft-block-copolymers synthesised by this way in the sense of "reactive blending" can be processed together with the corresponding adequate matrix material polyamide 6 or polyester into drawable filaments. After spinning and drawing under suitable conditions 1c-PEIA-fibrils modified by molecules of the basic polymer with diameters of less than 500 nm are detectable in the resulting filaments. The desired "microphase distribution" of the PA-modified respectively PET-modified 1c-PEIA-macromolecules as the reinforcing system components could be achieved. Moreover these graft-block-copolymers built by "reactive blending" in-situ have a high thermodynamic compatibility because of their chemical similarity to the primary structure of the respective matrix materials resulting in a relatively high reinforcing effect. These both aspects as well as the proceeding orientation of the 1c-PEIA-microphases by the filament, drawing cause, though optimising processes are still remaining, a remarkable increase of the tensile strengths as well as clearly improved initial moduli at a simultaneously raised stretchability of the 1c-PEIA-modified polyamide and polyester filaments. These effects could be achieved with PEIA-amounts of lower than 5 percentages by weight.