EN ISO 13468 Plastics - Determination of Total Light Transmittance of Transparent Materials

The standard “EN ISO 13468 Plastics - Determination of total light transmittance of transparent materials”, which is based on a European standard and later published by the International Standards Organization (ISO), consists of subsections published under the same title. Namely,

EN ISO 13468-1 Part 1: Single-beam instrument” describes a procedure for determining the total light transmittance of planar transparent and substantially colourless plastics in the visible region of the spectrum using a single-beam photometer with a specified CIE standard light source and photodetector. This standard cannot be used for plastics containing fluorescent materials. This standard is valid for transparent moulding materials, films and sheets with a thickness not exceeding 10 mm.

Total light transmittance can also be determined with a double-beam spectrophotometer as in the ISO 13468-2 standard. However, this standard provides a simple but precise, practical and rapid determination. This method is suitable not only for analytical purposes but also for quality control. Essentially colourless plastics include those that are slightly coloured. Samples thicker than 10 mm can be measured as long as the instrument can accommodate them, but the results may not be comparable to those obtained using samples thinner than 10 mm.

For the purposes of this standard, the terms and definitions given in “CIE publication No 17 CIE International lighting dictionary” as well as the following definition apply:

Transparent plastics are plastics whose light transmission is essentially uniform and which have high transmittance in the visible region of the spectrum. Objects are clearly visible through plastics which are transparent in the visible region, provided their geometrical shape is suitable.
Total luminous transmittance is the ratio of the transmitted luminous flux to the incident luminous flux when a parallel light beam passes through a sample.

Test specimens shall be cut from film, sheet, or injection-molded or compression-molded moldings. Specimens shall be free from defects, dust, grease, protective materials, adhesives, scratches, and stains, and shall be free from visibly visible internal voids and particles.

The samples should be large enough to cover the inlet port and the compensation port of the integrating sphere. For a 150 mm diameter sphere, a 50 mm or 60 mm diameter disc or a square with a side of the same length is recommended. Three samples should be taken from each sample of a given material unless otherwise specified.

Before testing, the samples are conditioned in accordance with the ISO 23 standard at 2 degrees plus/minus 50 degrees and 5 percent plus/minus 291 percent relative humidity for a certain period of time depending on the sample thickness and material. In this way, the samples reach thermal equilibrium. 16 hours is usually sufficient for samples thinner than 0,025 mm. More than 40 hours can be used for thicker materials.

The tester is installed in an atmosphere maintained at a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50 percent plus/minus 5 percent.

EN ISO 13468-2 Part 2: Double-beam instrumentation” describes a procedure for determining the total light transmittance of planar transparent plastics and substantially colourless plastics in the visible region of the spectrum using a double-beam scanning spectrophotometer. This standard cannot be used for plastics containing fluorescent materials. This standard is valid for transparent moulding materials, films and sheets with a thickness not exceeding 10 mm.

Total light transmittance can also be determined with a single-beam instrument as in ISO 13468-1. Essentially colourless plastics include those that are slightly coloured. Samples thicker than 10 mm can be measured as long as the instrument can accommodate them, but the results cannot be compared with those obtained using samples thinner than 10 mm.

For the purposes of this standard, the terms and definitions given in “CIE publication No 17 CIE International lighting dictionary” as well as the following definition apply:

Transparent plastics are plastics whose light transmission is essentially uniform and have high transmittance in the visible region of the spectrum. As long as their geometric shapes are suitable, objects are clearly seen through plastics that are transparent in the visible region.
Total spectral transmittance is the ratio of the transmitted radiant flux (both regular and scattered) to the incident radiant flux when a parallel beam of monochromatic radiation of a given wavelength passes through a sample.
Total luminous transmittance is the ratio of the transmitted luminous flux to the incident luminous flux when a parallel beam of light passes through a sample.

Samples shall be cut from film, sheet, or injection-molded or compression-molded molds. Samples shall be free from defects, dust, grease, protective materials, adhesives, scratches and stains, and shall be free from visibly visible internal voids and particles. Samples shall be large enough to cover the inlet port of the integrating sphere. For a 150 mm diameter sphere, a 50 mm or 60 mm diameter disc or a square with the same length as the side is recommended. Three samples shall be taken from each sample of a given material unless otherwise specified.

Before testing, the samples are conditioned in accordance with the ISO 291 standard at 23 degrees plus/minus 2 degrees and 50 percent plus/minus 10 percent relative humidity for a period of time depending on the sample thickness and material until thermal equilibrium is reached. For samples thinner than 0,025 mm, 16 hours is usually sufficient. For thicker materials, more than 40 hours is usually sufficient.

The tester is installed in an atmosphere maintained at a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50 percent plus/minus 10 percent.

Our organization, which has been trying to support businesses from every sector with its testing, measurement, analysis and evaluation studies carried out in a wide range for years, has a strong staff that closely follows the developments in the world in the field of science and technology and constantly improves itself. In this context, testing services in accordance with the "EN ISO 13468 Plastics - Determination of total light transmittance of transparent materials" standard are also provided to businesses.