d. Whiteness
Importance: High whiteness is a key indicator for products requiring color, such as light-colored plastics, rubber, and coatings.
Concerns: Impurity content (such as iron and calcium) can affect product whiteness, so special attention should be paid when selecting.
e. Surface Treatment (Core Technology for Flame Retardant Applications)
Reason for Treatment: Magnesium hydroxide is hydrophilic, while polymer materials (such as plastics) are hydrophobic. Direct addition results in poor compatibility and uneven dispersion, severely impacting the material's mechanical properties and processing flowability.
Treatment Method: Surface-coating (also known as "activation") the magnesium hydroxide particles with a silane coupling agent, stearic acid, or titanate coupling agent.
How to Determine:
Ask the supplier for surface-treated activated magnesium hydroxide and inquire about the type of coupling agent used.
Simple hydrophobicity test: Sprinkle a small amount of sample on the surface of water. The treated product will float (hydrophobic), while the untreated product will quickly sink to the bottom (hydrophilic).
f. Thermal Decomposition Temperature
Importance: Magnesium hydroxide begins to decompose and absorb heat at approximately 340°C. This temperature must be higher than the processing temperature of your material (e.g., injection molding or extrusion).
Reason: Otherwise, premature decomposition will occur during processing, resulting in blistering and reduced performance.
Suitability: Typical plastic processing temperatures are between 200-300°C, and magnesium hydroxide fully meets this requirement.
3. Select a reliable supplier and communicate effectively
Clarify your needs: Directly inform the supplier of your specific application (e.g., "for flame-retardant PP plastic") and key performance requirements.
Request samples and test reports: Request samples and corresponding technical data sheets (COA) from the supplier, and conduct testing and verification yourself or outsource it to a third party.
Understand production capacity and stability: Ensure the supplier can provide stable supply with minimal batch-to-batch quality fluctuations.
Weigh price and value: Don't just focus on unit price. Highly active products with surface treatments may cost more, but they can save processing time and improve final product quality, offering greater overall value.
4. Simple Identification and Verification Methods (Upon Receipt of Goods or Samples)
If specialized instruments are unavailable, the following methods can be used for preliminary evaluation:
Appearance Observation: The powder should be white, fine, and uniform, without lumps or discoloration.
Touch and Feel: Rub a small amount of the product between your fingers. High-purity, well-processed products should feel smooth and fine. If they feel rough or grainy, this indicates coarse particles or poor processing.
Hydrophobicity Test (Critical): Gently sprinkle a small amount of sample onto the surface of a still cup of water.
High-quality product (well-processed): The powder will float on the water for a while.
Low-quality product (unprocessed or poorly processed): The powder will quickly absorb water and sink to the bottom of the cup.
Acid Neutralization Test: Add a small amount of sample to dilute hydrochloric acid or white vinegar. The magnesium hydroxide should foam vigorously and dissolve quickly. After dissolution, the solution should be clear, with no significant insoluble residue.