Design Data for Plastics Engineers

Frontmatter

1. Mechanical Properties of Solid Polymers

Abstract

The properties of polymers are required firstly to select a material which enables desired performance of the plastics component under conditions of its application. Furthermore they are also essential in design work to dimension a part from a stress analysis or to predict the performance of a part under different stress situations involved. Knowledge of polymer properties is, as already mentioned in the preface, a prerequisite for designing and optimizing polymer processing machinery.

Natti S. Rao, Keith T. O'Brien

2. Thermal Properties of Solid and Molten Polymers

Abstract

In addition to the mechanical and melt flow properties thermodynamic data of polymers are necessary for optimizing various heating and cooling processes which occur in plastics processing operations.

Natti S. Rao, Keith T. O'Brien

3. Transport Properties of Molten Polymers

Abstract

The basic principle of making parts out of polymeric materials lies in creating a melt from the solid material and forcing the melt into a die, the shape of which corresponds to that of the part. Thus, as Fig. 3.1 indicates, melt flow and thermal properties of polymers play an important role in the operations of polymer processing.

Natti S. Rao, Keith T. O'Brien

4. Electrical Properties

Abstract

The use of plastics in the electrical industry as insulators for wire and cable insulation is well known. The application of engineering resins to make miniature electric components, printed circuit boards, conductive housings of computer equipment and the like, although not so well known, is increasing. Some of the electrical properties which are of importance in selecting a resin for these applications are treated in this section.

Natti S. Rao, Keith T. O'Brien

5. Optical Properties of Solid Polymers

Abstract

The intensity of light incident on the surface of a plastic is reduced as the light enters the plastic because some light is always reflected away from the surface. The intensity of light entering the plastic is further reduced as the light passes through the plastic since some light is absorbed, or scattered, by the plastic. The luminous transmittance is defined as the percentage of incident light which is transmitted through the plastic. For comparison purposes the exact test parameters are documented in ASTM D 1003. Some typical light transmission values are presented in Table 5.1 for most common optical plastics. Light transmission is a measurement of the transparency of a plastic.

Natti S. Rao, Keith T. O'Brien

6. External Influences

Abstract

Plastics parts are often used in an environment, in which an interaction between the polymer and a fluid like water, gas or organic liquids can take place. This may lead to deterioration or even failure of the part. Furthermore, plastics used in certain applications as in packaging foodstuffs should be resistant to the entry of oxygen or moisture, so that the contents do not deteriorate during the prescribed time span.

Natti S. Rao, Keith T. O'Brien

7. Extrusion

Abstract

Extrasion is one of the most widely used unit operations of polymer processing. Basically it consists of transporting the solid polymer in an extruder by means of a rotating screw, melting the solid, homogenizing the melt, and forcing the melt through a die (Fig. 7.1).

Natti S. Rao, Keith T. O'Brien

8. Blow Molding

Abstract

The different processes of blow molding, namely extrusion blow molding, injection blow molding and stretch blow molding are illustrated in the Fig. 8.1 to 8.4 [1], [2]. In Fig. 8.5 [2], in addition to the aforementioned processes the principle of dip molding is briefly explained.

Natti S. Rao, Keith T. O'Brien

9. Injection Molding

Abstract

Among the polymer processing operations injection molding (Fig. 9.1) has found the widest application for making articles which can be put to direct use.

Natti S. Rao, Keith T. O'Brien

Backmatter