Long time thermal aging test of stretch film
2017-06-15 10:09:08

 Long time thermal aging test of stretch film

Many stretch film manufacturers are most often heard and most afraid to hear is the "maximum operating temperature" or "relative temperature index", because these values ​​almost determine whether a stretch film is suitable for a finished product. For the customer, if the operating temperature recorded during the finished product safety test is higher than the maximum allowable temperature of the stretched film used, there are only two viable options:
1, switch to other high temperature can withstand the tensile film;
2, change the finished product design to reduce the operating temperature requirements.
But these two options, it is possible to greatly increase the cost of research and development, and even delay the development cycle, because the complex product design, often a small change will be led by a move. So, choosing a suitable or higher RTI stretch film is a better cost-effective way. For stretch film suppliers, it is one of the factors that can improve the competitiveness of their products by providing stretch films that are higher than the original category RTI. How can we effectively confirm the stretch film's RTI? The answer is through the LTTA test.
Definition and Related Standards of Tensile Film LTTA Test
LTTA is a fairly professional and widely used test project. The so-called LTTA, is Long Term Thermal Aging, that is, long-term thermal aging test abbreviation. As the UL's basic test project, LTTA is most commonly used to evaluate the properties of polymer materials, such as engineering plastics. The maximum temperature, i.e., the relative temperature index (RTI), can be deducted from the specified characteristic of the stretched film at 100,000 hours (i.e., half-life) with an "accelerated" thermal aging result of about 5,000 to 10,000 hours. In other words, the relative temperature index shows the heat resistance of a stretched film characteristic, that is, the ability of the stretched film to remain in the highest permissible temperature for a long time. Because of the many uses of polymer materials, such as electricity, heat, external forces, etc., each characteristic of the polymer material has a different RTI value when the application is not set. In addition, the LTTA test is used to evaluate the overall characteristics of the system and finished product, and the maximum permissible temperature for the entire system and finished product is called the maximum operating temperature (MOT). MOT is a combination of systems and finished products that are used to assemble stretch film components in known cases; in other words, overall assessment and limitation for the entire system and finished product. UL will be marked on each relevant standard "MOT can not be higher than any component within the system and any of the relevant characteristics of the rated temperature value."
Differences between LTTA and general safety testing
The stretched film, which is not subjected to a thermal aging test, is assumed to have the same relative temperature index as the original type (Generic) stretched film. The actual relative temperature index of the stretched film can be determined by the LTTA test when the stretched film is used for a product design and the operating temperature of the product is higher than the original temperature relative to the original category of the stretched film. Prolonged use of the ultimate safe temperature and the use of the environment to determine whether the stretch film is suitable for the product. The relative temperature index of the original type of stretched film is estimated by reference to past test data and chemical structures, with a relative temperature index list of ordinary grade stretched films attached to UL 746B (Polymer Material Standard - Long Term Characteristics Assessment).
LTTA is almost completely different from the concept and method of general safety or functional testing, and the exception is that LTTA does not have a pre-test deadline like a security test, nor does it have a functional test Compare the default test conditions. LTTA to observe the three variables "time, temperature, characteristics," the relationship between, because the control of change in the design, making the LTTA is not like a "test", but rather like "experiment", so LTTA is According to these three variables to design and observation, resulting in the relationship between the physical and chemical variables.