White Light Diffuser Panel

Light transmittance is one of the core properties of a diffuser panel and is directly dependent on the light transmittance of the base material.

PMMA (polymethyl methacrylate, acrylic): It is one of the most transparent plastic materials (with a transmittance of up to 90%-92%). Its high purity and low absorption of visible light mean that PMMA-based diffusers typically maintain high transmittance, making them suitable for applications requiring both high transmittance and uniform scattering (such as high-end display screens and precision lighting).
PC (polycarbonate): Its transmittance is slightly lower than that of PMMA (approximately 85%-89%), but the material itself has more stable transmittance for certain wavelengths of light (such as blue light). It is suitable for applications that require high uniformity but are not sensitive to extreme transmittance (such as outdoor lighting).
PS (polystyrene): Its transmittance is approximately 80%-85%. However, due to its low purity, impurities can easily be introduced, leading to reduced transmittance. Therefore, it is more suitable for cost-sensitive, low-end applications (such as standard indoor lighting covers) where light transmittance is less critical. Glass: It can achieve a light transmittance exceeding 90% and has virtually no risk of yellowing. However, it is heavy and fragile, and is therefore only used in specialized high-end applications (such as high-precision optical instruments).

The scattering effect depends on the refractive index difference between the substrate and the internal scattering particles, as well as the optical uniformity of the substrate itself:

The refractive index of the substrate is fundamental: different materials have different refractive indices (e.g., PMMA has a refractive index of approximately 1.49, PC has a refractive index of approximately 1.58, and PS has a refractive index of approximately 1.59). The greater the difference in refractive index between the added scattering particles (such as titanium dioxide or organic microspheres) and the substrate, the more intense the refraction/reflection of light at the interface, and the wider the scattering angle (e.g., a PS substrate with low-refractive-index particles exhibits a stronger scattering effect than PMMA).
Material Uniformity: PMMA and PC have more stable molecular structures, resulting in fewer impurities and more uniform light scattering. However, PS is prone to localized refractive index fluctuations due to internal stress generated during processing, which can cause "haze unevenness" and affect scattering consistency.

Weatherability (UV resistance, aging resistance, and yellowing resistance) determines the performance stability of a diffuser panel during outdoor or long-term use:

PMMA: It inherently has a certain degree of UV resistance, which can be further enhanced by adding UV-resistant additives. It resists yellowing after long-term exposure to sunlight and is suitable for applications such as outdoor advertising screens and streetlights.
PC: It offers superior UV resistance to PMMA (especially after UV-resistant modification) and is more weather-stable. It resists aging in high-temperature and humid environments, making it a common material for outdoor lighting and automotive lamps.
PS: Its molecular structure is easily damaged by UV rays, causing rapid yellowing and embrittlement with long-term use. It is only suitable for short-term indoor use (such as disposable lighting covers).

Mechanical properties (impact resistance, hardness, and toughness) determine the durability and installation suitability of a diffuser panel:

PC: It has extremely strong impact resistance (2-3 times that of PMMA) and excellent toughness, making it resistant to breakage. It is suitable for applications requiring impact resistance (such as children's lamps and car displays). PMMA: High hardness (surface wear resistance), but also brittle and prone to cracking under impact. Suitable for applications requiring a high surface finish but without severe impact (e.g., indoor display panels).
PS: Low mechanical strength and prone to brittleness, suitable only for low-impact applications (e.g., lighting covers for temporary exhibitions).

Heat resistance determines the stability of the diffuser in high-temperature environments (e.g., lamps near light sources, high-temperature equipment):

PC: High heat resistance (long-term operating temperature approximately 120°C, short-term operating temperature up to 130°C), resists deformation at high temperatures, suitable for applications such as high-power lamps and industrial equipment lighting.
PMMA: Moderate heat resistance (long-term operating temperature approximately 80-90°C), softens easily above 100°C, suitable for lower temperature environments (e.g., home lighting, general display screens).
PS: Poor heat resistance (long-term operating temperature only 60-70°C), prone to deformation and cracking at high temperatures, suitable only for ambient temperature applications.

The processing difficulty and cost of the material will indirectly affect the structural design and application scenarios of the diffuser:

PMMA: Easy to process (complex surface textures such as microprisms and frosted surfaces can be formed through injection molding and extrusion) and has high molding precision. It is suitable for diffusers requiring fine surface structures (such as high-uniformity diffusers for display screens), but its cost is relatively high.
PC: Slightly more difficult to process than PMMA (requiring higher temperatures and pressures), but it can be formed into thicker sheets or complex structures. Its high mechanical strength makes it suitable for integrated designs (such as a lamp housing + diffuser integration), and its cost is moderate.
PS: Simple to process and low in cost, but prone to internal stress after molding, making it difficult to create high-precision structures. It is suitable for low-cost, standardized, general-purpose diffusers.