The outline of a Course given in the Department of Polymer Engineering to 3rd and 4th year students at UMIST

S F Bush and J M Methven

Aim

To equip the student to analyse the properties and processes needed to design and manufacture polymer composite artefacts.

Learning Outcomes:

• Understand the meaning of Integrated Design and Manufacture for polymer composite products.
• To be able to analyse for impact, fatigue, fracture, creep, thermal conduction, gaseous permeation, in polymer products.
• To analyse the behaviour of fibre reinforced composites in their various forms.
• To be able to apply the concepts and analysis to practical examples in the engineering, construction, automotive, electrical, and packaging sectors.

Syllabus

Integrated Design and Manufacture:[1] the main choices of process and material types; design rules for relating process to product; process pathways and “order of processing steps” principle; design methodology exemplified by thermoplastic gas pipe distribution system: six design stages including screening out unsuitable materials. Failure modes: impact, fatigue, fracture and creep analysis. Stress analysis, thermal conduction, permeation of gases and application to packaging and gas containment generally.

Fibre reinforcement:[1] distinction between continuous, long, and short discrete fibres. Control of fibre orientation. Fibre touch and composite strength equations. Applications to thermoplastic injection mouldings, pipe and sheet extrusions and blow-mouldings: practical examples from automotive, textiles, drinks sectors.

Lightweight materials for design of sandwich panels:[2] classes of cellular plastics – for thermoset and thermoplastics. Manufacture of foams – materials, reaction injection moulding, thermoplastic (structural) foams. Structure and properties of foams – stiffness, thermal conductivity. Compounding for cost reduction and property enhancement: applications in automotive and electrical sectors. Manufacture of dough moulding compounds and sheet moulding compounds: mechanical properties from rule(s) of mixtures applied to 3 components (resin, filler and fibre).

Assessments

90% by written exam

Pre-requisites

Second year Engineering Materials

References

[1] Prof S F Bush

[2] Dr J M Methven

Report to Metal Industries Company Ltd.

S F Bush

Background and Objectives

Packaging films have been identified by MIC as a potential opportunity for local production in Trinidad. The major markets include rice packaging, processed meats, baked goods overwrap, pasta products and garment packaging. Within this broad range the company is particularly interested in (Ref 1):

• rice
• processed meat (bacon, sausages)
• pasta products (spaghetti, macaroni)

 
Specifically, co-extrusion of laminated film structures has been identified as a potential manufacturing process. Modern packaging film technology is nowadays quite sophisticated with (usually) several properties being required for each class of application. Thus the required barrier to oil, grease and moisture, the required optical properties such as gloss and transparency, and the required mechanical properties – tear strength and ductility for example, all will vary from application to application.

The best way to obtain the corresponding variety of film product from fundamentally one manufacturing operation is via multi layer structures of different polymers. Such structures may in principle be obtained by two methods:

1. extruding two or more films separately and then sticking them together (adhesion lamination);
2. running two or more molten extrudates together and cooling to make one film (coextrusion).

 
There are variants for both methods 1 and 2.

It has been assumed in composing this reort that MIC will wish to establish a facility which gives them flexibility to attack at least the three target markets listed above without incurring unnecessary material cost and equipment complexity. furthermore MIC will want to tailor the film structures to give the most economical product for each market.

The next section (2) tabulates the main film properties which are relevant to the market sectors which have been defined. The following section (3) tabulates the principal film materials, their properties and the costs of those properties – what is defined in (Ref 2) as the material untilities. In section (4) some of the salient fabrication factors as they may affect MIC’s choices are listed.

As will be appreciated new materials and variants of older materials are entering the market all the time. The tabulations given here contain therefore data as recent as this month (in connection with the new material EVOH) as well as fairly well-established data. Processing, particularly speeds, affects properties and this has been indicated. Some approximate estimates have had to be made (especially on costs) to present MIC with an overview of the key issues.

References

Ref 1: H Johnson to S F Bush dated 23rd September 1986
Ref 2: S F Bush, Utility and Complexity in the selection of Polymer Materials, Int Mats Eng Conf London, 5-7 November 1985