Page 64 - Template Tesis UTM v2.0

2.8.2 Thermoplastic

Thermoplastic can be described as a plastic material that is processed by

applying heat above its melting point (Tm). In this light, when adequate heat is applied,

plastic will be liquefied and softened enough to be processed. When the heat source is
removed, the temperature drops below its melting point (Tm) and solidify back to the

glass-like solid state. Moreover, in order to retain the thermoplastic properties, the

service temperature must be well below the melting point (Tm).

Thermoplastic materials are divided into categories based on the fundamental

morphological difference. These morphologies are described as crystalline, semi
crystalline and amorphous. Among of the thermoplastic materials are poly ether-ether

ketone (PEEK), polyetherimide (PEI), polyethylene (PE), polypropylene (PP),
Polyvinyl chloride (PVC), polycarbonate (PC), polylactic acid (polylactide), nylon

and teflon. PC has advantages such as high impact and heat resistance, dimension
stability, less corrosive and toxicidy, and apparently used in the aircraft field in the

fabrication of aircraft windshileds and canopies, pressure windows which able to resist

at high temperature, automotive components and industrial equipments [70].

2.9 Composite Processing Method

The processing technique of a composite is very crucial to achieve the desired
mechanical and physical properties of the products being produced at a reasonable

cost. In the composite field, the main concern is to identify materials that are cheap to

produce but capable to optimise the composite properties, as they are highly desirable,
especially when dealing with natural resources. There are many processes that can be

linked to the composite system, which can be categorised into conventional or

advanced methods. Wet lay-up is the simplest method to fabricate general purpose
products such as boats, benches, cable tray and table top. This process provides a high-

grade surface on the mould side. After an application of mould release to the mould
surface, a pigmented gel coat is applied to the mould and allowed to partially cure

before continuing with the lamination process. The hand lay-up process gives moulded

35