What makes plastic so popular?
The flexible properties of plastic are making it most preferred raw material for different applications. The industry is mushrooming at an exponential speed, overtaking industries like steel, copper, aluminium. Due to their flexible molecular structure, it is very easy to mould them into desired shapes. Polymers are made up of a long chain of identical structures called monomers. Technically, they are identified with different names like resins, polyethene, HDPE, PET, but commonly, they all are called plastic.
Plastic is, first of all, inexpensive in comparison to other products. This is why it is an easy substitute for expensive materials used in similar applications. Like plastic, fasteners are gaining popularity as they are inexpensive and rust proof as well. Moreover, they are easily used even after multiple rounds of recycling. Although, some of their properties might lose; still they are worth using in some domestic applications like garbage bags etc. Due to their flexible structure, they are fit to use in a different application that require different shapes and thickness.
Does plastic lose its properties when recycled?
If something is being treated, again and again, their molecular structure is being altered repeatedly, they will tend to lose some properties. Flexibility, melting point, appearance are some common properties that get altered after recycling. To assess the suitability of the plastic for the application after recycling, it is tested for its flow properties using Melt flow index tester. The recycled plastic is changed in granulated form. These granules are tested for their flow rate. How much-molten plastic flows in 10 minutes is called Melt flow index.
Standard Operating Procedure
It is important to understand that MFI does not determine the quality of the plastic, instead it tells about the suitability of the plastic for the application. For instance, the plastic used in moulding pipes must have low MFI to withstand the process to take the desired shape. Similarly, in applications like plastic utensils and toys, the MFI preferred is quite high than required in pipe moulding.
Melt flow index tester works on the temperature range of ambient to 400°C. This temperature is enough to melt the granules. This molten plastic comes out of the orifice which has a predefined diameter. After 10 minutes, a cutter cuts the thread like string made up of molten plastic. This molten plastic is taken and weighed. To determine the MFI, the weight in grams is divided by 10 minutes.