The Melt Flow Rate of Different Polymeric Materials

E3: Melt flow rate target for different polymer materials: 1) Understand the operating procedure of TWELVindex 2) Determining the melt flow rate of different polymer materials Introduction: Melt flow index is given in weight of extrudate (g / 10) With reference to FIG. 1, the melt flow index measured according to the condition-E (190 ° C., 2160 g) is called "melt index (MI)", which is the usual condition of polyethylene . Polypropylene requires the condition L (230 ° C., 2160 g) due to its high melting point and the melt flow index under the condition L is called "melt flow (MF)".

ISO 1133-1: 2011 Procedure for managing melt flow rate measurements. Melt flow index (MFI) is a measure of the ease with which a thermoplastic polymer melts. It is defined as the mass in grams of polymer flowing through a pipe of a particular diameter and length by the pressure applied by a particular weight. (A. V. Shenoy D, R. Saini 1986). It is an indirect way of measuring molecular weight with respect to melt flow. Since the viscosity depends on the specific gravity applied, MFI is inversely proportional to the viscosity of the molten polymer. In this test, sample pellets were placed in a cylinder with a die with a diameter of 0955 mm and a length of 8 mm at the bottom of the cylinder. Heat the polymer for a specific time and then measure the amount of flow through the die with a specific mass over a specific period of time. The melt flow rates of PLA and CNT are measured at 190 ° C and 195 ° C.

Polystyrene is a thermoplastic polymer synthesized by polymerization of styrene monomer. The starting materials for styrene synthesis include ethylbenzene and benzene. Polystyrene melts when heated above the melting temperature, and hardens when cooled. This property has been proven to be useful for the manufacture of various parts in the construction and electronics industries. Polystyrene can be produced using extrusion, molding and vacuum forming techniques. Expandable polystyrene (EPS) is polystyrene that fuses with the help of air and fuses to form blocks.

Oxidative degradation occurs when the polymeric material is subjected to elevated temperatures in the presence of air over an extended period of time, the rate and extent of which depends on the type and formulation of the polymeric material, temperature and exposure time. . This degradation reduces the tensile strength properties and toughness and ultimately leads to surface cracking and brittleness. The tensile strength and elastic modulus properties of the polymeric material decrease in proportion to the rate of rise in temperature while the elongation increases with increasing temperature.