Technical data sheets for plastic materials offer a snapshot of selected information and can provide a useful means of comparing test data. They can also be useful in quality testing. However, there are other considerations which a material specifier should take into account.
A material technical data sheet typically provides physical, mechanical, electrical and thermal test data. It can also show fire, environmental, chemical and regulatory compliance information. Technical data sheets do not tend to consider the long term performance characteristics of the plastic or the complex loading modes.
Product failure and data comparison
Permanent loading (creep) and cyclic loading (dynamic fatigue) have a greater potential to cause product failure in comparison to a single loading event. Long term properties ultimately influence product design and the performance of the final product in service. This is particularly relevant to companies investing in R&D and considering material selection for new products as incorrect material selection can prove very costly.
Care must be given when directly comparing the data found in technical data sheets. Producers in different territorial regions may publish data which appears the same but has been created using subtly different test methods (for example ISO, BS, ASTM, UL etc.) or using different test conditions (load and test temperature in the Melt Flow Rate test or the flexural stress in the Heat Deflection Temperature test).
Beyond the basic test data found within a technical data sheet are factors which can influence not only the final performance of a product manufactured from the modified plastic, but also its processibility and approval status. Simply adding a colourant to some plastics can have considerable affect, subject to the pigment used. This can result in changes to the crystallisation rate when processing which may affect dimensions due to shrinkage. Any fire rating (for example UL 94 yellow card) or expensive regulatory approval achieved with the base plastic may not carry the approval once modified.
Intended product application
Another consideration when reading material technical data sheets is the likely environment in which the final plastic product will be required to operate in. For instance some hygroscopic plastics, such as polyamides, exhibit performance variations in some tests dependent on the degree of water content. In these cases the technical data sheet will often carry two distinct columns of data; one showing dry as moulded (DAM) data and the other after moisture conditioning.
Consequently, when reviewing material technical data sheet information, it is vital to understand the context of the published data in terms of the specific material and the intended application.
Training course topics covered:
- What the properties mean and how to use them
- How to compare one material with another
- The relevance of data to the products
- An appreciation of the need to consider data values in context
- The limitations of datasheets
The course will enable attendees to consider how the information found on datasheets relates to the requirements of specific industry sectors, such as consumer products, automotive, medical, construction and others.
Dr Soroosh Bagheriasl is one of four Smithers Rapra experts presenting this two day training course.
Find out more:
Plastic Materials Technical Datasheets Training Course>
23-24 November 2016
Training Course Schedule>
Dates for 2016
Contact Training Business Lead Kerry Haralambou for more course information>