Why need to do an aging test?
Climate and is the sunlight irradiation damage paint, textiles, plastics, printing ink and other high polymer materials, the main reasons for the due to the light and moisture damage to the material, causing billions of dollars in economic losses each year.
This damage includes loss of light, discoloration, yellowing, cracking, peeling, embrittlement, strength reduction and stratification. Even the light and window of the room can cause some materials to age, such as pigments, dyes and other discoloration or discoloration.
Obviously, anti-aging and light stability are important for many products.Over the years, various methods have been used.Most researchers now use natural exposure tests, and the natural exposure method tests have many advantages: practical, cheap and easy to operate.However, most manufacturers are reluctant to wait a few years to see if a new improved product design is really improving.
In recent years, low-priced and convenient laboratory testing equipment has been developed, including the QUV accelerated aging device (ASTM G154) and q-sun xenon lamp test box (ASTM G155).(QUV is the most widely used aging detection device in the world.It is based on the principle that the short-wave length of ultraviolet light causes the most important damage to ageing materials.The q-sun test box simulates all the spectrum of sunlight, including ultraviolet, visible and infrared light.
Natural causes of product aging:
The biggest aging damage is caused by three factors: illumination, heat and humidity.Any of these three factors will cause material aging.They often work simultaneously, and the damage is greater than the individual effects of any of these factors.
Different materials have different sensitivities to light.For durable materials, such as most coatings, outdoor textiles, and plastics, the short wavelengths of ultraviolet rays are the cause of most of the polymer's ageing.However, for materials that are not so durable, such as pigments and dyes, long wavelengths of ultraviolet light and even visible light can cause severe aging.
As the temperature rises, the destruction of light increases.Although the temperature does not affect the main photoinduced reaction, it affects secondary chemical reactions. Laboratory aging tests must provide precise temperature control, and are usually accelerated by heating up.
Dew, rain and high humidity are the main causes of dampness.Our research shows that items placed outdoors will be in a wet state for a long time every day (an average of 8 to 12 hours per day).Studies have also found that dew formed by moisture is a major factor in outdoor humidity.Dew causes more damage than rain because it is attached to the material for longer periods of time and causes more severe moisture absorption.
Of course, rain is also very harmful to materials.The rain will cause heat shocks, such as when a car suddenly cools off in a hot summer heat and suddenly drops off in a shower.Mechanical erosion caused by rain wash will accelerate material aging, such as wood coating, water washing to remove aging surface layer, layer will not aging further aging exposed to the sun.
For indoor materials, the main effect of moisture is mechanical stress.It is caused by material trying to maintain a moist balance around it.The greater the humidity, the greater the stress that needs to be overcome.Although indoor objects such as textiles and ink are only exposed to the moisture environment, it is still an important factor in the aging of outdoor materials.Outside, relative humidity (RH) will affect the drying rate of a wet material.