ISO 6721-11-2019 pdf free.Plastics – Determination of dynamicmechanical properties.
This document specifies methods for determining a value of the glass transition temperature (Tg)from the dynamic mechanical properties measured during a linear temperature scan under heatingconditions. The glass transition temperature is an indicator of the transition from a hard and relativelybrittle glassy state to a rubbery or viscous liquid state in an amorphous polymer or in amorphousregions of a partially crystalline polymer.
Usually referred to as dynamic mechanical analysis (DMA), the methods and their associatedprocedures can be applied to unreinforced and filled polymers, foams,rubbers, adhesives and fibre-reinforced plastics/composites. The methods are limited to materials that are inherently stable aboveTg, i.e. amorphous materials that transform into a rubbery state or partially crystalline materials thatkeep their shape due to crystallinity.
Different modes (e.g. flexure, torsion, shear, compression, tension) of dynamic mechanical analysis canbe applied, as appropriate, to the form of the source material.Measured Tg values using instrumentation can vary as a result of material characteristics and/orthe test set-up. The temperature sensor in a DMA instrument is not in contact with the test specimenand therefore measures temperature of the environment surrounding the specimen under test. Theresulting data can vary with the heating rate applied.A procedure is included to take into account thethermal lag influencing the measured data.
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document. For dated references,only the edition cited applies. Forundated references, the latest edition of the referenced document (including any amendments) applies.
The instrument shall continuously monitor and record the sinusoidal load applied to the specimen, thecorresponding sinusoidal displacement, and the phase angle as a function of the measured temperature,in order to determine the storage modulus, loss modulus and loss factor. The load and displacementcapabilities of the equipment shall be sufficient for the specimens tested.
The temperature sensor should be positioned in the instrument as closely as possible to the sampleunder test, but ensuring it is not touching it.
The equipment shall be calibrated regularly, or when the testing mode or atmosphere is changed orwhen the temperature sensor is moved or changed.ISO 6721 pdf download.