SA (Styrene-Acrylonitrile Copolymer): Applications, Advantages & Injection Molding Guide

SA, or Styrene-Acrylonitrile Copolymer (SAN), is a transparent engineering thermoplastic that offers improved chemical resistance and thermal stability over polystyrene. It is widely used in applications that require stiffness, clarity, and ease of processing.

What Is SA?
SA is a copolymer of styrene and acrylonitrile. The addition of acrylonitrile enhances the chemical resistance, heat resistance, and mechanical properties of styrene, while maintaining transparency and ease of processing. SAN is often used as a standalone material or blended with other polymers (e.g., ABS, ASA) to enhance performance.

Key Applications of SA
Consumer Products
– Kitchen appliances (juicer bowls, blender jars)
– Cosmetic containers and packaging
– Transparent food storage products

Electronics & Appliances
– Battery housings and covers
– Monitor and television bezels
– Electric fan components and switches

Medical & Laboratory
– Transparent housings and tubing
– Diagnostic and analytical equipment
– Instrumental panels and dispensers

Automotive
– Interior trim components
– Transparent covers and indicator parts
– Knobs and vents

Retail & Displays
– Display panels and trays
– Brochure holders and signage
– Cosmetic organizers

Advantages of SA
– High clarity and good light transmittance
– Improved chemical resistance vs. polystyrene
– Greater thermal resistance (~100 °C)
– Rigid and scratch-resistant surface
– Good dimensional stability and gloss
– Easily colored and processed by injection molding

Injection Molding Guidelines for SA

1. Drying Requirements
SA absorbs some moisture and should be dried before molding for optimal clarity.
– Target moisture: <0.05%
– Drying temperature: 80 °C
– Drying time: 2–4 hours

2. Melt and Mold Temperatures
– Melt temperature: 200–270 °C (use lower end for thick parts)
– Mold temperature: 40–80 °C (avoid exceeding 60 °C for reinforced grades)
– Consistent mold temperature improves surface finish and shrink control

3. Injection Pressure & Speed
– Pressure: 350–1300 bar depending on wall thickness
– Speed: Medium to high injection speed to ensure fill and gloss

4. Runner and Gate Design
– All conventional gate types suitable
– Avoid small gates on thick parts to reduce stress concentration
– Polished mold surfaces enhance clarity and finish

Common Molding Issues
– Flow lines or weld marks: Use proper gate location and speed
– Bubbles or streaks: Improve drying and reduce injection speed
– Shrinkage: Typical shrinkage ~0.3–0.7%, influenced by mold temp and geometry
– Warping: Use uniform wall thickness and adequate mold venting

Final Thoughts
SA offers a strong combination of transparency, thermal stability, and chemical resistance for aesthetically demanding components. Its processing ease and performance make it an ideal material for clear consumer products, appliances, and lab equipment.
Need help selecting the best SA grade or optimizing for clarity and toughness? Our team is here to provide expert recommendations for your tooling and processing needs.