Common protective screen material analysis

Polycarbonate

Polycarbonate (PC) is a high-molecular-weight polymer that contains carbonate groups in its molecular structure. It can be categorized into different types based on the ester group, such as aliphatic, aromatic, and aliphatic-aromatic polycarbonates. Among these, aliphatic and aliphatic-aromatic polycarbonates generally have lower mechanical properties, which limits their use in engineering plastics. Currently, only aromatic polycarbonates are produced on an industrial scale. Due to its unique structure, polycarbonate has become one of the fastest-growing general-purpose engineering plastics among the five main categories.

Physical Properties

Polycarbonate has a density ranging from 1.20 to 1.22 g/cm³, a linear expansion coefficient of approximately 3.8×10⁻⁵ cm/cm°C, and a thermal deformation temperature of around 135°C. It is a colorless, transparent material with excellent heat resistance, impact resistance, and flame retardancy (UL94 V-0 rating without additives). Compared to polymethyl methacrylate (PMMA), it offers better impact resistance, higher refractive index, and improved processing performance. However, PMMA is typically more cost-effective and suitable for large-scale production via bulk polymerization. As polycarbonate production scales up, the price gap between the two materials is gradually narrowing.

Resistance and Limitations

Polycarbonate is not resistant to strong acids or alkalis, but it can be modified to improve its chemical resistance. It also exhibits poor abrasion resistance, so surface treatments are often required for applications involving wear and tear.

Applications of Polycarbonate

Polycarbonate is widely used across various industries, including construction, automotive, medical devices, aerospace, packaging, and electronics. Its versatility and performance make it ideal for a range of applications:

• Construction: Polycarbonate sheets offer excellent light transmission, impact resistance, UV stability, and dimensional accuracy. They are increasingly replacing traditional inorganic glass in building materials. China alone uses over 70,000 tons annually, with projections reaching 140,000 tons by 2005.
• Automotive: With good impact resistance, thermal stability, and weather resistance, polycarbonate is used in car parts like lighting systems, dashboards, and bumpers. In developed countries, about 40–50% of polycarbonate is used in electronics, electrical, and automotive sectors. In China, this proportion is currently around 10%, but demand is expected to grow rapidly.
• Medical: Polycarbonate is suitable for medical equipment due to its ability to withstand sterilization processes without degrading. It is used in hemodialysis machines, syringes, and surgical masks.
• Aerospace: Polycarbonate is used in aircraft and spacecraft components due to its strength, durability, and resistance to extreme conditions. A single Boeing aircraft may contain over 2,500 polycarbonate parts, and a single aircraft may use around 2 tons of the material.
• Packaging: PC bottles are popular for water and beverage storage due to their lightweight, transparency, and resistance to deformation under hot or corrosive conditions. Demand is expected to grow at over 10% annually, reaching 60,000 tons by 2005.
• Electronics: Polycarbonate’s excellent insulation, flame resistance, and dimensional stability make it ideal for electronic housings, power tools, and other components requiring precision and durability.
• Optical Lenses: Polycarbonate’s high light transmittance, refractive index, and impact resistance make it ideal for lenses in cameras, microscopes, projectors, and eyewear. The global optical industry consumes over 20% of polycarbonate, growing at over 10% per year.
• Optical Discs: Polycarbonate is the primary material for CDs and DVDs. The global optical disc industry consumes over 20% of polycarbonate, with significant growth in China.

Acetate Fiber

Acetate, also known as cellulose acetate, is a man-made fiber derived from cellulose through esterification with acetic acid. Its chemical formula is (C₆H₇O₂)(OOCCH₃)₃n. It is commonly used in textiles, cigarette filters, film bases, and plastic products.

Performance of Cellulose Acetate

Cellulose acetate has low density, moderate strength, and good elasticity. It has low boiling water shrinkage and is sensitive to high temperatures. It absorbs moisture well, has good thermal properties, and is resistant to chlorine bleach and dry cleaning. However, it is not easily dyed with conventional dyes and requires special disperse dyes for effective coloring.

Use in Apparel and Linings

Acetate fibers are used in clothing for their luxurious feel, softness, breathability, and comfort. Over 40% of global cellulose acetate consumption goes into linings, improving garment appearance, comfort, and durability. It is also used in blends with natural and synthetic fibers to create versatile fabrics like crepe, georgette, and satin.

PETG Material

PETG is a transparent, amorphous copolyester composed of terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol (CHDM). It offers excellent thermoforming, toughness, weather resistance, and chemical resistance. PETG is easier to process than acrylic or PC and is used in sheeting, bottles, films, and cosmetic packaging.

Main Features of PETG

• Excellent thermoforming performance
• High impact resistance
• Good weather resistance and UV protection
• Easy to process and modify
• Chemically resistant
• Environmentally friendly and food-safe
• Cost-effective compared to PC

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