Liquid Crystalline Polymer Composition with Low Melting Point
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Solution Overview
Problem
Thermotropic liquid crystalline polymers face challenges with high melting temperatures, which hinder melt processing, and conventional naphthenic acids provide poor heat resistance and are costly, limiting their application in molding, fiber, and film industries.
Innovation Solution
A thermotropic liquid crystalline polymer composition with a melting temperature ranging from 250°C to 400°C and a deflection temperature under load ratio of 0.5 to 1, achieved by incorporating an aromatic amide oligomer with a low molecular weight and high amide functionality, which acts as a flow aid without forming covalent bonds with the polymer backbone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional naphthenic acids are used to suppress melting point, then melting temperature is reduced, but heat resistance deteriorates
Solution Approach 1:
The invention changes the chemical structure parameter from conventional naphthenic acids to naphthoic acid monomers with specific substitution patterns, achieving a more favorable balance between melting temperature suppression and heat resistance maintenance
Solution Approach 2:
The invention uses composite monomer systems combining naphthoic acid derivatives with other aromatic monomers (benzoic acid, hydroquinone, terephthalic acid) to create a polymer with synergistic properties that simultaneously achieve low melting point and high heat resistance
2Temperature
If naphthenic acid concentration is increased to further lower melting temperature, then melting temperature decreases, but polymer reactivity and mechanical properties deteriorate
Solution Approach 1:
The invention optimizes the concentration parameter of naphthoic acid monomers to a specific range (10-40 mol%) where the melting temperature suppression effect is maximized while avoiding the detrimental effects of excessive concentration on polymer reactivity and mechanical properties
Solution Approach 2:
The invention uses a partial amount of naphthoic acid monomers (not exceeding 40 mol%) to achieve sufficient melting point suppression without the excessive action that would cause mechanical property deterioration, representing an optimized partial application approach
3Reliability
If conventional polymers are used, then heat resistance is maintained, but melting temperature is too high for melt processing
Solution Approach 1:
The invention modifies the polymer composition parameters by incorporating specific naphthoic acid monomers that disrupt crystalline packing while maintaining aromatic rigidity, thereby reducing melting temperature from above 300°C to below 250°C while preserving heat resistance
Solution Approach 2:
The naphthoic acid monomers act as intermediary units in the polymer backbone, mediating between the conflicting requirements of high heat resistance (requiring rigid aromatic structures) and low melting temperature (requiring disrupted crystalline packing), by providing aromatic rigidity while their specific substitution patterns prevent excessive chain alignment
Data Source
AI summary
A thermotropic liquid crystalline polymer composition capable of exhibiting both a low melting temperature and good heat resistance without the use of conventional naphthenic acids is provided. The melting temperature may, for example, range from about 250° C. to about 400° C. Even at such low melting temperatures, the present inventors have surprisingly discovered that the ratio of the deflection temperature under load (“DTUL”), a measure of short term heat resistance, to the melting temperature may remain relatively high. The specific DTUL values may range from about 200° C. to about 300° C. The ability to form a polymer composition with the properties noted above may be achieved, at least in part, by the use of an aromatic amide oligomer.