The lighting industry has long used translucent glass and plastics for various aesthetic and functional purposes. As lighting shifts from traditional sources to LED-based, solid-state lighting technology, more and more applications of outdoor and indoor appears such as advertising light box and luminous word signs. Polycarbonate diffuser and acrylic diffuser are the two types of lights cover, most commonly used by us at present. these two materials have their own characteristics, customers often choose them based on their requirements. So, what is the difference between Polycarbonate and Acrylic diffuser and how to choose between them? This article will help understand that.
What is Polycarbonate diffuser?
Polycarbonate diffuser is made of optic-modified material which is made based on raw polycarbonate material and a diffused additive is added. The diffused additive can be evenly distributed in the material, when the light passes through the sheet, the effect of refraction, reflection and scattering occur when the diffused additive particles are encountered, so that the light can be evenly passed through the sheet without hot spot, as result of a homogeneity appearance. The lever of light diffusing could be controlled by raw material manufacture.
What is acrylic diffuser?
Acrylic diffuser is made of optic-modified material which is made based on raw acrylic material and a diffused additive is added. It can effectively transform point or line light sources into soft and uniform surface light sources.
besides achieving good transmittance, it also covers the hot spot of light source. It is one of the best light diffusion materials for LED lighting products.
Acrylic VS Polycarbonate diffuser
Typical Physical Properties
As Light diffuser material made base on Raw materials, so they keep the raw material properties except the light transmittance which changed according to the design requirement
| UNITS | ASTM TEST | ACRYLIC | POLYCARBONATE | |
| Specific gravity | D792 | 1.19 | 1.2 | |
| Light transmittance | % | D1003 | 60% to 90% | 40% to 80% |
| Tensile elongation | % | D638 | 4.5 | 135 |
| Heat deflection temperature | °F | D648 | 195 | 280 |
| Maximum continuous service temperature in air | °F | 160 | 240 | |
| Flexural strength | psi | D790 | 17,000 | 13,500 |
| Tensile strength | psi | D638 | 10,000 | 9,500 |
| Tensile modulus of elasticity | psi | D638 | 400,000 | 345,000 |
| Flexural modulus of elasticity | psi | D790 | 480,000 | 345,000 |
| Compressive strength | psi | D695 | 17,000 | 12,500 |
| Izod impact | ft-lbs/in | D256 | 0.4 | 12.0 - 16.0 |
| Coefficient of linear thermal expansion | in/in/°Fx10-5 | D696 | 4 | 3.8 |
| Dialectic strength | V/mil | D149 | 430 | 380 |
| Water absorption (immersion 24 hours) | % | D570 | 0.2 | 0.15 |
| shrinkage rate | % | 0.2% to 0.5% | 0.5 to 0.7% |
* Light transmittance vary according to the design requirement to achieve a homogeneous lit appearance.
Acrylic VS Polycarbonate diffuser, which is better?
The answer varies when comparing acrylic and polycarbonate for light-diffusing applications. Both can be simple to manufacture. Both have near-identical optical properties. Acrylic diffuser tends to have outstanding optical properties, is the best light transmission of any plastic, and is naturally UV-stable. Polycarbonate diffuser offer good light transmission and excellent diffusion of LED hot spots like acrylic. It also features good impact and heat resistance. In addition, polycarbonate sheet can be cold-formed into complex shapes such as curved light diffusers.
Impact Strength
Acrylic will shatter when hit with enough force. Polycarbonate is virtually unbreakable.
when safety and handling is a concern per the application, we recommend using Polycarbonate diffuser.
Optics
Acrylic diffuser tends to transmit vary from 40% to 90% of all light, whereas polycarbonate diffuser transmits vary from 40% to 80%. If the application requests a diffusing transmit around 90%, then Acrylic will be your choice. But if the Light transmittance requirement is below 80%, then both are available, then you should go to check other factors.
Temperature Resistance
Polycarbonate has high-temperature resistance, higher than Acrylic. If your application environment demands a temperature on the diffuser over Acrylic, then polycarbonate could be used such as car headlights. But usually, the temperature will not go that high in the application of our life.
Scratch Resistance
Acrylic is significantly more resistant to scratches and abrasions than polycarbonate. While the difference in resistance can be reduced by adding special coatings to polycarbonate, but this will make additional costs and be expensive. So acrylic still comes out ahead.
Cost
acrylic diffuser and polycarbonate diffuser have similar prices in the market. But vary according to different grade materials, So the cost will be depending on the final raw materials, and the process method of your application according to the design of the environment they are used in.
Flammability
Acrylic is a moderately flammable polymer, and no additives currently exist to reduce this. Polycarbonate has an inherent resistance to fire which can be increased with additives without losing transparency. when safety on fire is a concern per the application, we recommend using Polycarbonate diffuser.
Weatherability
Acrylic is exceptionally resistant to weathering and is UV-resistant, making it a popular choice for outdoor use. On the other hand, polycarbonate is more vulnerable to UV exposure and will yellow and crack over time. This difference can be mitigated with additives, but acrylic still stands up better to outdoor conditions.
In summary
Above is the difference between polycarbonate and acrylic diffuser, Normally, for recess mounting linear light used polycarbonate diffuser, for some special requirements such as very high transmittance could select transparent PMMA diffuser.
KUSLA provides a range of materials for traditional and LED light-diffusing polycarbonate and acrylic sheet. We also offer run-to-size and plastic machining services to optimize yields and fit customers’ specific needs. Contact us for more information on light-diffusing materials and how to order them.
