Polyamide Pressure Vessel with Optimized CH2-Ratio
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Solution Overview
Problem
Current pressure vessels, such as type IV and type V tanks, face limitations in structural integrity, acid resistance, and permeation properties, particularly when used for hydrogen or compressed natural gas, where stringent safety measures are required.
Innovation Solution
A pressure vessel with a hollow body comprising endless fibers embedded in a thermoplastic matrix, where the matrix consists of polyamides with a CH2-ratio of at least 5.5 and less than 10, calculated by determining the number of aliphatic monomeric units and their CH2 groups, and accounting for aliphatic units weighing at least 10% of the total matrix weight, providing improved structural integrity and acid resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If type IV tanks are used (thermoplastic liner wrapped with thermoset composite), then weight is reduced, but recyclability is lost and buckling occurs
Solution Approach 1:
The invention changes the chemical composition parameters of the thermoplastic matrix by specifying polyamides with CH2-ratio between 5.5 and 10, and controlling the amount of aliphatic monomeric units (10-80 wt%). This parameter optimization provides both structural integrity to prevent buckling and recyclability while maintaining weight reduction benefits.
Solution Approach 2:
The invention uses a composite structure consisting of endless fibers (carbon, glass, or aramid) embedded in a thermoplastic matrix, creating a Type V tank that combines the light weight of thermoplastics with the structural strength of fiber reinforcement, eliminating buckling while maintaining recyclability.
2Strength
If polyamide 6 is used in the matrix, then structural integrity is improved, but resistance against acids and salts deteriorates
Solution Approach 1:
The invention optimizes the chemical structure parameters of the polyamide by controlling the CH2-ratio (5.5-10) and the content of aliphatic monomeric units (10-80 wt%). This specific parameter range provides the right balance between structural integrity from crystallinity and chemical resistance from the polymer structure.
Solution Approach 2:
The invention introduces local chemical diversity by incorporating different aliphatic monomeric units (adipic, sebacic, dodecanedioic acid) in specific proportions. This creates local variations in the polymer chain that enhance both mechanical properties and chemical resistance to acids and salts.
3Strength
If polyamide 12 and carbon fibers are used (Type V tank), then structural integrity is improved, but permeation properties deteriorate
Solution Approach 1:
The invention optimizes the polyamide matrix parameters (CH2-ratio 5.5-10, aliphatic monomeric units 10-80 wt%) to achieve the right balance between structural integrity and permeation resistance. The controlled crystallinity and molecular structure provide both mechanical strength and barrier properties.
Solution Approach 2:
The invention creates a homogeneous distribution of aliphatic monomeric units within the polyamide matrix, ensuring uniform properties throughout the material. This homogeneity provides consistent permeation resistance while maintaining structural integrity.
Data Source
AI summary
This invention relates to a pressure vessel comprising a hollow body comprising endless fibers embedded in a thermoplastic polymer, in which the thermoplastic polymer comprises one or more polyamides containing one or more aliphatic monomeric units, wherein the one or more polyamides have a CH2-ratio of at least 5.5 and less than 10, calculated by □ identifying the number of different aliphatic monomeric units in the one or more polyamides; □ determining the number of CH2 groups per aliphatic monomeric unit for each of these different aliphatic monomeric units; □ calculating the sum of the so determined numbers of CH2 groups; □ dividing said sum by the number of different aliphatic monomeric units in the one or more polyamides; taking into account only the aliphatic monomeric units present in the one or more polyamides in an amount of at least 10 wt % with respect to the total weight of the one or more polyamides.