Polyamide Blend Composition for Low-Viscosity Composite Impregnation
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Solution Overview
Problem
The preparation of thermoplastic-based composites is limited by high viscosity issues during processes like consolidation in closed molds at low pressure and continuous injection-pultrusion, which hinders efficient impregnation of fibrous reinforcements with polyamides in the molten state.
Innovation Solution
A thermoplastic composition comprising a high molecular weight polyamide (a) combined with a non-evolutive low molecular weight polyamide (b), where polyamide (b) has a melt viscosity below that of polyamide (a) and a number-average molecular weight lower than polyamide (a), stabilizing the melt viscosity at a reduced level, allowing for improved fluidity without altering mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high molecular weight polyamide is used to maintain mechanical properties, then strength and toughness are improved, but melt viscosity increases and fluidity deteriorates
Solution Approach 1:
The patent combines high molecular weight polyamide (providing mechanical strength) with low molecular weight polyamide (providing fluidity) to create a blended composition that achieves both high strength and good processability. The low molecular weight component acts as a viscosity modifier that does not significantly compromise the mechanical properties provided by the high molecular weight component.
Solution Approach 2:
The patent changes the molecular weight parameter of the polyamide blend by incorporating low molecular weight polyamide (Mn < 10,000) alongside high molecular weight polyamide. This parameter change reduces the overall melt viscosity while maintaining adequate mechanical properties, enabling better fluidity for manufacturing processes.
2Ease of manufacture
If low molecular weight polyamide is used to improve fluidity, then melt viscosity decreases and impregnation improves, but mechanical properties deteriorate
Solution Approach 1:
The patent merges low molecular weight polyamide (improving fluidity) with high molecular weight polyamide (maintaining mechanical strength) in a blended composition. The low molecular weight component enhances impregnation and fluidity without significantly compromising the mechanical properties provided by the high molecular weight component.
Solution Approach 2:
The patent creates a composite polyamide system by blending polyamides with different molecular weights. The low molecular weight polyamide (5-20 wt%) serves as a viscosity modifier in the composite, improving processability while the high molecular weight polyamide maintains the structural integrity and mechanical properties.
3Productivity
If low molecular weight polyamide is used to reduce viscosity, then production time is reduced, but molecular weight and mechanical strength decrease
Solution Approach 1:
The patent combines low molecular weight polyamide (reducing viscosity and production time) with high molecular weight polyamide (maintaining mechanical strength). The blended composition enables faster processing while preserving adequate mechanical properties through the synergistic effect of the two components.
Data Source
AI summary
The invention relates to a thermoplastic composition having improved fluidity in the molten state, comprising at least:(a) a polyamide that has a melt viscosity greater than or equal to 50 Pa·s, and(b) a non-evolutive polyamide having a melt viscosity lower than the melt viscosity of said polyamide (a), above 0.8 Pa·s, and having a number-average molecular weight Mn lower than that of said polyamide (a),said composition having a melt viscosity that is stabilized at a value below the melt viscosity of said polyamide (a),said polyamide (b) having:a concentration of amine end groups (AEG) and/or of carboxyl end groups (CEG) less than or equal to 20 meq/kg, ora concentration of amine end groups (AEG) greater than or equal to 25 meq/kg; a concentration of acid end groups (CEG) greater than or equal to 25 meq/kg; and a concentration of blocked end groups (BEG) greater than or equal to 25 meq/kg.