PSA D47 5531 Rubbers - Bleaching of Parts

The purpose of the procedure described in the standard “PSA D47 5531 Rubbers - Bleaching of parts” developed by the French automobile company Renault is to characterize the resistance of rubber parts (insulating tape, slides, window encapsulation, trim and the like) to swelling and bleaching. This test method is performed only on finished parts. The material and production process of the tested sample must be fully compatible with the parts installed on the vehicle.

For the purposes of these standards, bleaching refers to the whitish surface appearance of a rubber part due to the migration of products (accelerators, application additives, etc.) contained in the rubber formulation.

In principle, this test consists of subjecting a rubber part to various accelerated ageing processes that can highlight the change in surface appearance characterized by bleaching. Three independent test methods are used to validate the part. The samples tested for each method are at least three in number and are taken from various locations.

Major test equipment used in these tests includes:

• The weather meter must comply with the test method mentioned in the PSA D27 1389 standard.
• The sunlight device (light booth) must comply with the test method of the PSA D15 1343 standard.
• The grey scale is used to assess the deterioration in accordance with the NF EN 20105 A02 standard. This scale is used in nine degrees with a black border.
• The ventilated oven is set at 70 degrees plus/minus 2 degrees.
• The cold chamber can be adjusted from minus 40 degrees to plus/minus 3 degrees.
• Distilled or deionized water should have a resistivity greater than or equal to 100.000 Ω cm.
• The conditioned room should have a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50 percent plus/minus 5 percent.
• White glass jars with sealed lids should have a capacity of 1 liter.
• Polyethylene bags should be heat-sealable or have an airtight closure system.
• Cotton wool should have a surface density greater than or equal to 450 g/m2.
• The wiping paper should be made of white, absorbent, lint-free cotton.
• A solution of 50/50 volume demineralized water/ethanol is required for cleaning and sparging the samples.

The samples shall be conditioned for at least 24 hours at 23 degrees plus/minus 2 degrees and 50 percent plus/minus 5 percent relative humidity in the climatic chamber before testing. The manufacturing date of the tested parts shall not exceed 3 weeks. For each test method, 4 samples shall be prepared, three of which shall be taken from different parts intended for testing. The last shall be stored as a reference in an aluminum foil in a cool room at 4 degrees plus/minus 2 degrees, away from light and moisture. Before testing, the parts shall be cleaned with a 50/50 volume solution of demineralized water/ethanol applied with a white lint-free cotton cloth. When cleaning, the cloth shall be thoroughly but not excessively wetted and the samples shall not be subjected to any particular strain (friction). This cleaning is to harmonize the appearance of the parts and to eliminate any traces of contamination. Clean without rubbing with a white lint-free cotton cloth.

In the first test method, artificial ageing is performed using the weather-o-meter (WOM) according to the test method of the PSA D27 1389 standard. This test consists of subjecting three samples to 1 exposure cycle (i.e. 168 hours) in artificial light representing sunlight (filtered Xenon lamp) and intermittent rainfall simulating rain.

In the second test method, poultry is matured according to the PSA D47 1165 standard test method. This test consists of placing three samples in a warm and wet atmosphere. The test conditions correspond to:

In the third test method, aging is done according to the table given in the standard.

The test is performed in complete darkness, alternating the exposure times of the samples in distilled water at 70 degrees and in air at 23 degrees and 50 percent relative humidity. The duration of the test protocol is two weeks.

Three samples taken from three different parts are placed in jars approximately two-thirds filled with deionized water at 70 degrees. The jars are then sealed and stored in a ventilated oven set at 70 degrees for 24 hours. The samples are completely immersed in water.

The samples are then removed from the jars and stored in the dark for 24 hours in a conditioned room. The storage location can be a drawer or a cardboard box. Contact between the support and the parts should be minimal to prevent any surface deposits of the part on the support.

The samples are placed back into their jars in a ventilated oven set at 70 degrees for 24 hours without water change, and then left in the conditioned room in the dark for 24 hours.

Finally, they are placed back into their jars in the oven set at 70 degrees for 10 hours without changing the water, and then left in the dark in the conditioned room for 10 hours.

Among the numerous tests, measurements, analyses and evaluation studies carried out for businesses in various sectors, our organization also provides testing services defined in the “PSA D47 5531 Rubbers - Bleaching of parts” standard with its trained and expert staff and advanced technological equipment.