TABLE OF CONTENTS Since each end product calls for particular properties, the selection of the most suitable resin for each application is very important. Resin selection is not an easy job. The problems must be clearly defined beforehand. Careful investigation of the end-use properties must be made. Moreover, resin requirements vary with the blow moulding procedure and the equipment available.
Quite generally, items requiring stiffness, high strength, hardness, such as containers for household detergents or chemicals, should be made of HDPE resins (these items currently represent the bulk of the blow moulding market). For squeeze bottles and flexible items such as toys, low-density polyethylene (LDPE) resins are more suitable.
The inherent physical properties of a resin may be modified by altering processing and operating conditions during the fabricating process, starting in the extrusion or injection machine and ending in the blowing mould. The main influences are those exerted by heat (or cooling) and pressure, and the time and duration of these influences are essential.
The term polymer is a combination of the prefix poly, meaning many and the suffix mer, which means unit . The combination, loosely translates to: many units.
The term plastic is derived from the description of a type of mechanical deformation under a load. More properly, it would be said plastic is a term applied to a material that will undergo plastic deformation.
Since many polymers will plastically deform, the term plastic was applied and stuck. Many polymers do not, plastically deform.
