What is modified talc powder?
Modified talc powder refers to a functional powder material whose surface has been treated physically or chemically to improve its compatibility, dispersibility, and binding properties with polymer matrices (such as plastics and rubber).
Simply put, modification is like giving talc powder a new coat. This coat allows it to better interact with other materials, thereby enhancing the performance of the final product.
Why modify talc powder? (Purpose of Modification)
Natural talc powder has a hydrophilic and oleophobic (hydrophilic and oleophobic) surface, which makes it:
Difficult to disperse evenly in organic polymers and prone to agglomeration.
Weak interfacial bonding with the polymer matrix creates stress concentration points, resulting in reduced mechanical properties.
High hygroscopicity affects the performance of products in humid environments.
The core purpose of modification is to address these issues, specifically:
Improving dispersibility: Enabling a more even distribution of talc powder in the matrix and reducing agglomeration.
Enhance interfacial compatibility: Build a strong "bridge" between talc powder and the matrix, improving bonding strength.
Improve mechanical properties: Significantly increase the tensile strength, flexural modulus, and impact strength of composite materials.
Reduce hygroscopicity: Improve the stability of products in humid environments.
Add new functions: Such as improving heat resistance and processing fluidity.
Main modification methods
1. Surface coating modification: Use substances such as resins or surfactants to coat the surface of talc powder particles through physical adsorption. This method is relatively simple, but the effects may not be as long-lasting as chemical modification.
2. Chemical coupling modification (most commonly used and most effective): Use a coupling agent to chemically react with the hydroxyl (-OH) groups on the talc powder surface, forming a strong chemical bond. The other end of the coupling agent is compatible with or reactive with the polymer matrix.
Silane coupling agents: Suitable for a variety of polymers, particularly thermosetting resins (such as epoxy resins) and some thermoplastics.
Titanate coupling agents: They are particularly effective for polyolefins (such as PP and PE), effectively reducing system viscosity and improving processing fluidity.
Aluminate coupling agents: Similar to titanates, they are commonly used in plastics such as PVC and PP and are relatively low-cost.
3. Mechanical and chemical modification: During the ultrafine grinding process, high-energy mechanical forces are applied to activate the surface of the talc powder particles, creating fresh surfaces and active sites. Simultaneously, modifiers are added to achieve simultaneous grinding and modification.