Improving the performance of composite materials? Modifying inorganic powders is the key!-2
III. Main methods and functions of inorganic powder modification
1. Surface chemical coating (most commonly used)
Method: Use coupling agents (such as titanate, aluminate, silane coupling agent), surfactants, organic acids, etc. as modifiers. One end of these molecules is an inorganic-philic group that can bind to the powder surface; the other end is a long chain that is organic-philic and can entangle or react with the polymer matrix.
Function: Build a "molecular bridge" between powder and polymer, greatly improving compatibility and binding force.
Metaphor: "put on" a lipophilic coat for the hydrophilic powder particles so that they can better integrate into the "oily family" of organic polymers.
2. Precipitation reaction modification
Method: Through chemical reaction, a dense and functional precipitation layer is formed on the surface of the powder (such as using stearate to react on the surface of calcium carbonate to form a calcium stearate layer).
Function: Modification also plays the role of reducing surface energy and changing from hydrophilic to hydrophobic. The process is relatively simple.
3. Mechanochemical modification
Method: During the process of ultra-fine grinding or high-intensity mechanical stirring, the modifier is added at the same time. Mechanical force creates a fresh surface, activates and increases the temperature of the particles, promoting the reaction of the modifier with the particle surface.
Function: To realize the integration of crushing and modification with high efficiency.
4. High energy surface modification
Method: Use plasma, ultraviolet, microwave and other energy to act on the particle surface to generate active points or directly graft polymers.
Function: Usually used to prepare high-end functional composite materials.
IV. Specific benefits brought by modification (value reflection)
The value and performance of modified inorganic powders have undergone a qualitative leap:
1.From "cheap padding" to "performance enhancement":
Unmodified: Although the cost is reduced after adding it, it often causes the material to become brittle and the strength to decrease.
After modification: It is firmly combined with the matrix and can play a role in reinforcing and toughening (such as modified nano-calcium carbonate used in automobile plastic parts), achieving "increase and quality improvement".
2.Significantly improved processing performance:
Evenly dispersed, no lumps, reduced equipment wear, improved production efficiency, and made the surface of the product smoother.
3.Give new functionality:
Flame retardancy: Modified aluminum/magnesium hydroxide becomes a highly efficient flame retardant.
Antibacterial properties: modified powder loaded with silver ions.
Electrical/thermal conductivity: Conductive coating of powder.
Weather resistance/UV resistance: Improve aging resistance through surface treatment.
4.Reduce overall costs:
On the premise of ensuring or even improving performance, more cheap inorganic powders are allowed to be added to replace expensive resins, thereby reducing formulation costs.
Summary
In the field of inorganic powder materials, "modification" is a key step in deep processing and value improvement. It represents:
The transformation from "raw materials" to "functional products".
The leap from “cost reduction” to “value creation”.
The core technology to solve the "compatibility" problem between powder and application system.
