A GUIDE TO HOW PLASTICS ARE TESTED AND WHY

Since different plastics have so many different applications, it’s vital to ensure you choose the best polymer for the job. In order to do this, you need to know the basic properties of the plastics you plan to use, but how do you find this out? Through plastic testing, of course. Plastic testing can be done in many ways, and a lot of these ways can be combined, in order to ensure you’re picking the best plastic for your intended use. So, how can you test your plastics? Melt Flow Testing Melt flow testing is one of the most common and essential forms of plastic testing. A small amount of the thermoplastic sample is heated to a specific temperature, melted to a fluid and forced through a die. This sample’s weight and volume are recorded, giving the melt flow rate (MFR) and the melt volume rate (MVR). This test is designed to find the amount of mass or volume that flows through the die at specific temperatures in order to determine how the polymer will perform in a number of different processing techniques and to compare batches of material. Impact Testing There are two types of impact testing, drop tower and pendulum. The main purposes of these tests are to measure the resistance of plastic by dropping a dart of different weights onto the plastic at different heights and velocities. This method can be used both to measure the resistance of the plastic, but also how much energy the sample will absorb. In each stage of the test process, if a sample passes, the drop weight is increased by one unit, whereas if it fails, the drop weight is decreased by one unit. The end goal is to calculate the Impact Failure Weight – the point at which 50% of the test samples will fail under the impact. Mechanical Testing Mechanical testing is the process of testing elements of plastic such as the stress and tensile properties, compressional properties and the peeling properties, or how strong the bonds of polymers are. These tend to be the tests that determine the suitability of plastic in a specific form or use, rather than just of the plastic itself, for example testing the compression and bond strength of a water bottle to make sure the plastic is suitable enough to be minimized in size, but also that the bonds are not going to break and any water leak out. Rheology Rheology tests are undertaken when a polymer is in a melt phase in order to test how the stress in a material or the force applied is related to the deformation of the material. The reason for doing so is that in understanding the rheological properties of a polymer can help to optimise the product and product press with minimal product degradation, resulting in greater cost efficiency and less waste during production. Thermal Testing Thermal testing of plastics allows for measuring complications like ageing processes, the effect of additives and the influence of varying production conditions on a polymer. Differential Scanning Calorimetry (DSC) is a commonly used technique when it comes to examining chemical and thermal decomposition and melting. Why Do We Need to Test Plastics? There are a number of reasons why it is crucial to test the properties of plastics using the above methods: Testing Before Scaling up Production: Companies would waste a lot of money by producing 10,000 units of a product and it not being suitable so they might test the first 100 units produced. This is to make sure results are consistent, and the product is up to the job before they move onto mass manufacture and production. Health & Safety: Some applications for plastics, such as food packaging, absolutely have to be tested before widespread use. It is essential to ensure that the packaging doesn’t break down or contaminate food under different conditions like microwaving or freezing. Identifying Weaknesses and Failures: There’s no way in which the weaknesses of a plastic could be discovered before mass supply without testing. It will save plastics producers a lot of angry customers if they ensure their products are up to scratch before distribution rather than supplying obviously faulty goods. Identifying Timescales: Testing plastics to understand their materials and their strength and durability is crucial for some applications, for example, it would be necessary to test plastic used for underground piping to estimate how long it will last underground before it needs to be replaced. At Rayda, we can manufacture plastics to your specific requirements. For more on what we can do for you, take a look at our about page.

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