MODUK DEF STAN 93-7 PDF

This Standard relates to several types of nylon in the form of granules (NSC Approved Item Name - PLASTICS MOULDING MATERIAL) which are suitable for the production of moulded or extruded articles for electrical purposes. Such articles will be resistant to many organic liquids such as lubricants and hydrocarbon fuels. For nylon material for mechanical purposes only, reference should be made to DEF STAN 93-8.

Mouldings and extrusions produced from the specified materials are not suitable for electrical applications where the freouencv exceeds 400 Hs.

The types of materials to which this Standard applies are as follows (see notes 1 and 2):

General purpose electrical (GPE) types.

Type 66 GPE. For use when highest rigidity and/Or heat distortion temperature is of primary importance under conditions of low humidity. The maximum water absorption of'this type is relatively high (s).

Type 6 GPE. For similar uses to type 66 GPE where slightly lower rigidity and heat distortion temperature are acceptable. As for type 66 GPE the maximum water absorption is relatively high (10%).

Type 11 GPE. Por use when flexibility is of primary importance. It has the least resistance to creep at elevated temperature Under load but the lowest maximum water absorption (2%), with correspondingly superior dimensional stability under humid conditions.

Type 610 GPE. For use when properties intermediate between type 6 OPE and 11 GPI are required. Tho maximum water absorption (3.9%) is loss than half that of type 66 GPE with correspondingly superior dimensional stability under humid conditions.

Weather resistant electrical (WE) types. Types 66 WE, 6 WE, 11 WE, and 610 WE - as for corresponding GPE type but for use when weather resistance is of primary importance. The electrical properties may be inferior to those of GPE types.

Heat stabilised electrical (HLE) types. Types 66 HLE, 6 HLE, 11 HLE, and 610 HLE - as for corresponding GPE type but for use in hot dry air or warm air of high humidity. These types may be found to have higher resistance to light than the GPE types, but may have inferior electrical properties.

Nucleated (N) material. Some types of material may contain additives nucleating agents) designed to promote fine crystal structure and quick setting in the mould. These materials generally, however, show low elongation at break in the as moulded' state. Materials containing nuoleating agents are given the additional designator 'N', eg, type 66 GPNE.

Grades of material. Eaoh type of material may be supplied as an injection moulding grade (a medium melt-nriscosity version) or as an extrusion or high impact grade (a high melt-viscosity version).

Colour. The general purpose (GPE) types may also be supplied in a range of colours in addition to natural colour. The weather-resistant (WE) types are black and the heat stabilized (HLE) types are normally supplied in natural colour modified by the additives which are necessarily present.

Notes: 1. Under certain conditions of use and in the presence of atmospheric oxygen, all nylon materials undergo gradual degradation resulting in permanent embrittlement. The rate of degradation is increased by rise in temperature, the presence of water or water vapour, or exposure to direct sunlight. The general purpose (GPE) types are not recommended for outdoor use es peclally when exposed to direct sunlight. The resistance to degradation is substantially inereased by the incorporation of small quantities of certain additives (stabilizers) as in the WE and HLE types but the useful life of articles fabrioated from these materials will still be determined by the ambient conditions. In general, the higher the ambient temperature and humidity, the shorter will be the life. The GPE types, for example, will have a relatively short useful life, months, rather than years at temperatures above 80°C in dry conditions or above 50°C in wet conditions if there is free access of air to the surfaces of the article.

The figures for the limits given in Tables A and B apply to material tested in the 'as moulded' condition which is the condition specified for quality control testing. Nylon is not necessarily used in this condition and the figures quoted should not be used as data for nylon other than 'as moulded'. The undermentioned properties of all types of nylon are changed with water content. It should be noted that the water-absorption properties of the WE, HLE, and MS types are similar to those of the corresponding GPE types. An increase in water content will:

decrease tensile strength

increase elongation at break

increase flexibility

increase impact strength

decrease hardness

decrease eleotrioal resistance

increase dimensions.