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Transparency

Transmission of Visible Light


TransparencyTransparency (or transmission of visible light) is characterized by light transmittance, i.e. the measured percentage of incident light transmitted through a standardized plastic specimen.

The higher the transmittance %, the higher the transparency


Transparency has no specific unit. Transmittance value is generally reported in the percentage of light transmitted.

The transparency or translucency of plastics depends on the type and structure of the polymer/crystallinity and types of additives, fillers, colors, etc. used.

  • Generally, amorphous plastics are transparent – e.g. acrylics, PC, and PS, ABS, PEI, etc.

  • Semi-crystalline or crystalline polymers are translucent or opaque as there are differences in refractive indices between the crystalline regions and amorphous regions – e.g. PE, PP, PBT, PET, nylon

Although PET and PP are crystalline, films of these materials are transparent (this because these films are bi-axially oriented – stretched in two directions – which orientates the polymer molecules in the plane of the film. Hence, when light passes through the film, there is no refraction because of this orientation)



Check out more on Transparency:

 » Light Transmittance Percentage Values of Several Plastics
 » Factors Affecting the Transparency of Polymer
 » Common Standard to Measure Transparency
 » Applications of Transparent Polymers



Factors Affecting the Transparency of Polymer


As the percentage crystallinity increases the polymer becomes progressively less clear due to the increase in density (which in turn decreases the speed of light passing through it). However, the clarity of crystalline plastics can be improved by quenching or random polymerization.

Further, the transparency of polymers (e.g. PP) can be considerably improved by using additives that act upon the growth and size of the crystal structure. These additives are known as nucleators and clarifiers.

Transmittance of light is also dependent on thickness – hence many polymers transmit light as thin films. Among thermosets such as unsaturated polyester, reinforcements interfere in transmittance.

Any chemical change in polymer-like degradation or oxidation or diffusion may impact transparency. The appearance of scratches or surface flaws as a result of exposure image light transmittance.

Apart from the factors mentioned above, steps such as coloration, heat treatment, and mechanical processing during production can affect optical properties.

A material with good transparency will have high transmittance and low haze


Haze is measured as the percentage of incident light scattered by more than 2.5° through the plastic specimen.


Common Standard to Measure Transparency


How easily light can penetrate a substance is usually determined by ASTM D1003 - Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics.

This test method covers the evaluation of specific light-transmitting and wide-angle-light-scattering properties of planar sections of materials such as essentially transparent plastic. Two procedures are provided for the measurement of luminous transmittance and haze.

  • Procedure A uses a hazemeter, and
  • Procedure B uses a spectrophotometer

Material having a haze value greater than 30% is considered diffusing and should be tested in accordance with Practice E2387.

Haze and luminous-transmittance data are especially useful for quality control and specification purposes.

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Transparency


Applications of Transparent Polymers


Some of the successful applications of transparent include automotive taillight lenses, safety glasses, window glazing, display cases, food packaging films, agriculture greenhouses, optical instruments, etc. Since plastics have superior impact resistance than glass, transparent plastics such as polycarbonate, PMMA, etc. have replaced glass in many other applications.

Applications of Transparent Polymers


Find commercial grades matching your property target using "Property Search – Transmission, Visible" filter in Omnexus Plastics Database:

Omnexus Plastics Database - Property Search


Light Transmittance Percentage Values of Several Plastics


Click to find polymer you are looking for:
A-C     |      E-M     |      PA-PC     |      PE-PL     |      PM-PP     |      PS-X

Polymer Name Min Value (%) Max Value (%)
Amorphous TPI, Moderate Heat, Transparent 58.0 58.0
Amorphous TPI, Moderate Heat, Transparent (Food Contact Approved) 58.0 58.0
Amorphous TPI, Moderate Heat, Transparent (Powder form) 58.0 58.0
ASA - Acrylonitrile Styrene Acrylate 1.050 1.070
ASA/PC Blend - Acrylonitrile Styrene Acrylate/Polycarbonate Blend 1.150 1.150
CA - Cellulose Acetate 90.00 90.00
CAB - Cellulose Acetate Butyrate 90.00 90.00
Celllulose Diacetate-Gloss Film 92.70 92.70
Celllulose Diacetate-Integuard Films 90.26 90.26
Celllulose Diacetate-Matt Film 16.80 16.80
Cellulose Diacetate-High Slip Film 92.70 92.70
Cellulose Diacetate-Semitone Films 54.00 54.00
CP - Cellulose Proprionate 90.00 90.00
COC - Cyclic Olefin Copolymer 91.00 91.00
ETFE - Ethylene Tetrafluoroethylene 95.00 95.00
EVA - Ethylene Vinyl Acetate 80.00 80.00
FEP - Fluorinated Ethylene Propylene 96.00 96.00
HDPE - High Density Polyethylene 80.00 80.00
LDPE - Low Density Polyethylene 80.00 80.00
MABS - Transparent Acrylonitrile Butadiene Styrene 88.00 88.00
PA 11 - (Polyamide 11) 30% Glass fiber reinforced 80.00 80.00
PA 11, Conductive 80.00 80.00
PA 11, Flexible 80.00 80.00
PA 11, Rigid 80.00 80.00
PA 12, Flexible 80.00 80.00
PA 12, Rigid 80.00 80.00
Polyamide semi-aromatic 80.00 80.00
PC (Polycarbonate) 20-40% Glass Fiber Flame Retardant 80.00 80.00
PC - Polycarbonate, high heat 88.00 89.00
PET - Polyethylene Terephthalate 70.00 90.00
PETG - Polyethylene Terephthalate Glycol 88.00 91.0
PFA - Perfluoroalkoxy 93.00 93.00
PMMA - Polymethylmethacrylate/Acrylic 80.00 93.00
PMMA (Acrylic) High Heat 80.00 93.00
PMMA (Acrylic) Impact Modified 80.00 92.00
PP (Polypropylene) Copolymer 85.00 90.00
PP (Polypropylene) Homopolymer 85.00 90.00
PP Homopolymer, Long Glass Fiber, 30% Filler by Weight 1.100 1.100
PP Homopolymer, Long Glass Fiber, 40% Filler by Weight 1.200 1.200
PP Homopolymer, Long Glass Fiber, 50% Filler by Weight 1.300 1.300
PP, Impact Modified 0.880 0.910
PPA - Polyphthalamide 30% Mineral 0.00 0.00
PPA, 33% Glass Fiber-reinforced 0.00 0.00
PPA, 33% Glass Fiber-reinforced High Flow 0.00 0.00
PPA, 45% Glass Fiber-reinforced 0.00 0.00
PS (Polystyrene) Crystal 88.00 88.00
PS, High Heat 80.00 90.00
PVC, Plasticized 75.00 85.00
PVC, Plasticized Filled 1.150 1.350
PVC Rigid 80.00 80.00
SAN - Styrene Acrylonitrile 86.50 91.00
SAN, 20% Glass Fiber-reinforced 1.200 1.400
SMA - Styrene Maleic Anhydride 1.050 1.080
SMMA - Styrene Methyl Methacrylate 80.00 91.40


Commercially Available Highly Transparent Polymer Grades



Disclaimer: all data and information obtained via the Polymer Selector including but not limited to material suitability, material properties, performances, characteristics and cost are given for information purpose only. Although the data and information contained in the Polymer Selector are believed to be accurate and correspond to the best of our knowledge, they are provided without implied warranty of any kind. Data and information contained in the Polymer Selector are intended for guidance in a polymer selection process and should not be considered as binding specifications. The determination of the suitability of this information for any particular use is solely the responsibility of the user. Before working with any material, users should contact material suppliers in order to receive specific, complete and detailed information about the material they are considering. Part of the data and information contained in the Polymer Selector are genericised based on commercial literature provided by polymer suppliers and other parts are coming from assessments of our experts.

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