HDT/Vicat Testing Systems
As thermoplastics do not have a definite melting point that precisely marks the transition from solid to fluid, analysis of the slow softening they undergo with increasing temperature is an important element in determining quality and performance. Two key tests that measure this are Vicat softening temperature and heat deflection temperature (HDT).
The Vicat softening temperature describes the point at which a 1mm² circular indenter or cylindrical punch, is able to penetrate 1mm into the sample at applied loads of 10N and 50N. HDT is the temperature at which a standard test bar deflects a specified distance under a load. It is most often utilized to determine short-term heat resistance and distinguishes between materials that may sustain light loads at high temperature versus those that lose their rigidity over a narrow temperature range.
Zwick offers HDT and Vicat softening temperature testing systems that operate on the same measurement and control platform as all other testing systems. This provides a tremendous advantage to customers running a variety of different tests within a single lab. Lab managers are able to best align staff resources in support of testing goals, as operators are not required to learn and engage with multiple software interfaces.
Melt Index Testing
Zwick has developed two extrusion plastometers with automated features that streamline the test process and improve laboratory efficiency. The Aflow extrusion plastometer for determining the melt mass flow rate (MFR) and melt volume flow rate (MVR) has been designed for high throughput environments. Automated features that improve speed and reliability include automatic parameter control and force control, which automatically adjusts test loads up to 50kg. Automatic parameter control is particularly useful for polymers with an unknown MFR, where operator influence in the determination of parameters could lead to reductions in measurement accuracy. Another automated feature is push-button pre-compacting and cleaning, which saves additional operator time and allows staff resources to concentrate on other tasks within the test lab.
Zwick’s Mflow extrusion plastometer has been designed for typical quality applications in areas such as QA and goods inward checks, which are performed to validate lot quality prior to acceptance of a material shipment. It incorporates program-controlled weight positioning and removal, which streamlines the testing process by eliminating the need for an operator to manually position the weights required for each test. The modular design of the Mflow enables easy upgrading and retrofitting. For example, it may be fitted with extrudate cutters, a displacement transducer for MVR measurement and a weight-lifting unit.
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Additional information on melt index testing systems and HDT/Vicat softening temperature systems may be found here.
