Is The Polymer Orientation Can Influence the Mechanical Properties of Thermoplastic Composites?

Shamsuri AA

Published on: 2019-10-22

Abstract

Polymer orientation is generally known as an alignment of polymer molecular chains in solid state. It is a unique phenomenon which takes places in each moulding process. The long-chain molecules of polymer will flow in molten state and harden in the mould in certain orientation. It is known that the orientation of polymer in the thermoplastic products is not very crucial because there is no reinforced filler in the systems that can significantly influence their mechanical properties.

Keywords

Polymer; Thermoplastic products; Moulding

Editorial

Polymer orientation is generally known as an alignment of polymer molecular chains in solid state. It is a unique phenomenon which take places in each moulding process. The long-chain molecules of polymer will flow in molten state and harden in the mould in certain orientation. It is known that the orientation of polymer in the thermoplastic products is not very crucial because there is no reinforced filler in the systems that can significantly influence their mechanical properties. The thermoplastic products are usually moulded by means of injection moulding or compression moulding technique since these processes required less time and the massive production can also be done [1,2].

However, there are differences in term of mechanical properties between these two techniques especially when the materials used for moulding products are made from thermoplastic composite materials. Thermoplastic composites are commonly prepared through melt-mixing method by using internal mixer or extruder machine [3,4]. The distribution of filler used in the thermoplastic composite materials is relatively good via this method [5]. The orientation of polymer in the prepared thermoplastic composite materials after mixed is not very significant compared to the moulded products. This is because the polymer orientation in the unmoulded products is typically random. The major difference between injection moulding and compression moulding techniques in the moulded thermoplastic composite products is the polymer orientation. The orientation of polymer for injection moulded products is unidirectional whereby the molten thermoplastic composite material was forced into a mould cavity at high pressure, thus it transferred in one path only for filling up the cavity. On contrary, the compression moulded products have multidirectional polymer orientation due to the molten thermoplastic composite material transferred randomly to the mould by compressed force.

The thermoplastic composite products with unidirectional polymer orientation frequently provided the consistent mechanical properties results that are why they have been used in Proficiency Testing Program by ASTM International [6]. On the other hand, the multidirectional polymer orientation of the thermoplastic composite products regularly possessed variable mechanical properties results with high standard deviation values [7]. Moreover, unlike sole thermoplastic, the reinforced filler within the thermoplastic composite products has induced the variation of the results between unidirectional and multidirectional polymer orientations.

So, is the polymer orientation can influence the mechanical properties of thermoplastic composites? Yes, this is because the different techniques for production of thermoplastic composite products have given the different polymer orientations due to the different types of exerted forces.

References