Composite Material Manufacturing via Steam Explosion Devolatilization
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Solution Overview
Problem
Existing methods for manufacturing composite materials, such as wood-based plastics, face issues like poor compatibility between natural fibers and plastics, leading to weak mechanical properties and operational inefficiencies, particularly when using wet web formation methods which can result in plastic loss, quality problems, and environmental concerns due to solvent use.
Innovation Solution
A method involving a devolatilization process that uses a steam explosion to remove water and volatile matter from a wet mixture of natural fibers and plastics, enhancing compatibility through the use of silanes which form covalent bonds with cellulose fibers, allowing for higher temperatures and mechanical mixing to create a highly homogeneous precompound, thus improving mechanical properties and reducing environmental impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If wet web formation method is used to manufacture composite material, then homogeneous distribution of plastic particles and compatibility improving agents is achieved, but plastic powder gets loose from the web and scatters causing operational stoppages and quality problems
Solution Approach 1:
The invention applies preliminary action by using steam explosion to pre-treat the natural fibers before composite formation. The steam explosion opens the hydrogen bonds and hornified structures of dry wood and natural fibers, creating a fibrillized state that allows for better subsequent bonding with plastic particles. This preliminary fibrillization prevents plastic powder from loosening during later processing stages.
Solution Approach 2:
The invention changes the physical-chemical parameters of the natural fibers through steam explosion treatment. The high temperature and pressure conditions of steam explosion fundamentally alter the fiber structure, opening hydrogen bonds and creating a more reactive surface area. This parameter change enables the fibers to maintain strong bonding with plastic particles throughout the manufacturing process.
2Strength
If dry wood and natural fiber materials are mixed at high temperature in molten plastic state, then mixing is achieved, but the strongly hydrogen bonded and hornified fibers cannot be opened and fibrillized resulting in low reactive surface area
Solution Approach 1:
The steam explosion treatment is applied as a preliminary action before the high-temperature mixing with molten plastic. This preliminary treatment opens the hydrogen bonds and hornified structures at lower temperatures, creating a fibrillized state with high reactive surface area. This allows subsequent bonding at lower temperatures while maintaining strong bonding strength.
Solution Approach 2:
The invention utilizes phase transitions of water during steam explosion (liquid to vapor) to achieve fiber modification. The rapid heating and phase change of water within the fiber structure creates internal pressure that opens hydrogen bonds and hornified structures, enabling fibrillization without requiring extremely high temperatures during the subsequent plastic mixing stage.
3Loss of substance
If traditional drying methods are used to remove water from wet mixture, then water removal is achieved, but the cellulose web is too weak to carry its own weight and cannot be dried
Solution Approach 1:
The steam explosion process changes the physical parameters of the fiber network through high temperature and pressure treatment. This creates a fibrillized structure with increased inter-fiber bonding capacity, enabling the web to support its own weight during the drying process. The parameter changes occur before drying, allowing subsequent efficient water removal.
Solution Approach 2:
The steam explosion treatment is applied as a preliminary strengthening action before the drying stage. The high energy input from steam explosion creates a robust fiber network structure that can withstand the mechanical stresses of drying. This preliminary strengthening enables subsequent efficient water removal without web failure.
4Strength
If compatibility improving agents are used to enhance bonding between natural fibers and plastic, then adhesion is improved, but excessive formation of hydrogen bonds between natural fibers occurs
Solution Approach 1:
The steam explosion process extracts or removes the excessive hydrogen bonding between natural fibers by breaking them apart through high energy treatment. This creates a fibrillized state where the fibers are separated and have reduced inter-fiber hydrogen bonding, allowing compatibility improving agents to work more effectively without competing hydrogen bond interference.
Solution Approach 2:
The steam explosion fundamentally changes the bonding parameters of the natural fiber system. The high temperature and pressure conditions break existing hydrogen bonds and create a new fiber surface state with reduced hydrogen bonding tendency. This parameter change allows for better control of hydrogen bond formation during subsequent processing stages.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the production of composite materials with enhanced mechanical properties and reduced environmental impact by ensuring better bonding between fibers and plastics, avoiding issues like plastic sticking during drying and improving manufacturing efficiency, even with compositions unsuitable for traditional wet web formation.
Implementation Method 1
A method involving a devolatilization process that uses a steam explosion to remove water and volatile matter from a wet mixture of natural fibers and plastics
Implementation Method 2
enhancing compatibility through the use of silanes which form covalent bonds with cellulose fibers
Data Source
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AI summary
The invention relates to a method for manufacturing a composite material comprising natural fibres such as lignocellulosic fibres, a thermoplastic material and a compatibilizing compound. The composite material is being manufactured by mixing (M) the substances with each other, and thereafter by mechanically pressing and/or by drying with heat the formed mixture in order to remove water. A wet mixture with 41 -99,8 % water is being formed, whereafter in order to manufacture a composite material having an internal network structure that keeps material together by chemical bonds between the thermoplastic substance and the natural fibre substance, the wet mixture is being fed to a devolatilization process (D), in which water and other volatile substances are being removed by pressure change, heat and mechanical mixing, whereby the structure of the lignocellulosic fibres is optionally modified.