Calcium sulfate whisker

Buyers should focus on the aspect ratio (length-to-diameter ratio), which typically should be above 20:1 to ensure effective reinforcement. Key parameters include a purity level of ≥98%, whiteness ≥90%, and a moisture content of <0.5%. For high-performance applications, verify the tensile strength (approx. 20 GPa) and modulus of elasticity to ensure the whiskers can effectively enhance the mechanical properties of plastics, rubber, or friction materials.

It is primarily used as a high-strength reinforcing filler in thermoplastics (PP, PA, PVC) to improve heat resistance and dimensional stability. It is also widely utilized in friction materials (like brake pads) to replace asbestos, in papermaking to improve opacity and smoothness, and in environmental coatings due to its non-toxic and flame-retardant properties.

Ensure the supplier provides a Material Safety Data Sheet (MSDS) and complies with REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) for European markets. For use in food-contact plastics or medical devices, the product must meet FDA or relevant ISO standards. Since it is often used as an eco-friendly alternative to asbestos, verify its non-fibrous hazardous classification.

Raw whiskers are hydrophilic, which can lead to poor dispersion in organic polymers. You should inquire if the supplier offers surface-modified whiskers using silane or titanate coupling agents. Proper surface treatment enhances interfacial adhesion, reduces viscosity during processing, and significantly improves the impact strength of the final composite material.

The main risks include moisture absorption during sea transit, which can cause clumping and render the product unusable. Always insist on moisture-proof packaging (e.g., multi-layer paper bags with PE inner liners). Additionally, ensure the HS Code (typically 283329) is correctly declared to avoid customs delays or incorrect tariff applications.

Prioritize Audited Suppliers who have undergone third-party verification by SGS or TÜV Rheinland. Request a Certificate of Analysis (COA) for the specific batch and ask for Scanning Electron Microscope (SEM) images to confirm the actual morphology and dimensions of the whiskers before placing a bulk order.

For bulk chemical orders, prices are sensitive to raw material costs (gypsum) and energy prices. Negotiate based on annual volume commitments rather than one-off spot buys to secure a 10-15% discount. Regarding logistics, FOB (Free On Board) is recommended if you have a reliable freight forwarder, as it allows better control over the shipping timeline and costs compared to CIF.

Use Secured Trading services provided by Made-in-China.com to ensure payment is only released upon confirmation of shipment. For first-time large orders, consider a Pre-shipment Inspection (PSI) to verify that the chemical composition and packaging meet your contract specifications.