Adequately characterizing the elastic recovery of materials used to manufacture seals such as those required in hydraulic equipment is critical to assuring long term seal safety and function. METTLER TOLEDO's Dynamic Mechanical Analyzer, DMA/SDTA861e, successfully investigates soft sealing elastics mechanical properties to encourage product durability and performance.

In hydraulics, ensuring that seal materials can recover after deformation caused by pressure is critical. Determining how seals behave within a manufacturer's set temperature range helpsdefine how long, how safely, and how well these specialseals will work. METTLER TOLEDO mounted a series of investigations to predictif materials used in seals behave according to manufacturer expectation using the DMA storage modulus for analysis. The DMA was used to determinethe test materials' mechanical properties as a function of time, temperature and frequency, which was shown to accurately define a particular material's ability to store mechanical energy as elastic energy.

Calculating Glass Transition
Glass transition represents the low temperature use limits for seals, which is calculated using factors such as viscosity and energy dissipated in the material. Historically, several different methods have been used to perform these calculations some better suited to certain materials than others. Which method is used is a critical piece of reporting data when determining the glass transition point.For the purposes of the experiments represented in the accompanying figures, glass transition temperatures were calculated using maximum loss asthis was clearer than loss factor.

Materials and Methods
For series of measurements depicted, four materials were available: nitrile butadiene rubber (NBR); low temperature NBR; fluoroelastometer (FKM or FPM); and thermoplastic polyurethane (TPU). Cylindrical test specimens were prepared (ø = 5 mm, h = 5 mm) and tested as follows: compression for the deformation mode; -60 ̊C to +120 ̊C for the temperature range; 3 K/min for the heating range; and 20 µm for deformation amplitude. The diagram in figure 1 shows the logarithmic analysis of the materials using the DMA storage and loss modulusplus the loss factor. The individual processes of the storage modulus clearly show the different material properties in terms of elasticity.

An Effective Quality and Process-Optimization Tool
Ultimately, calculated glass transition points using DMA matched manufacturer temperature limits, proving the METTLER TOLEDO DMA can enable recreation of material process parameters for effective quality testing or to successfully optimize production throughout a manufacturer's development process to ensure critical partslike hydraulic seals will perform as expected when integrated into their real-world applications.

For more on how Dynamic Mechanical Analysis can help accurately test elastic sealing materials, visit http://us.mt.com/us/en/home/products/Laboratory_Analytics...

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Mettler-Toledo International Inc.
Im Langacher, Zip Code 8606
Greifensee, Switzerland
E-Mail : ePublicRelations@mt.com
Phone : +41-44-9443385
Website : www.mt.com

About Author:
METTLER TOLEDO specializes in the area of precision instruments for professional use. METTLER TOLEDO laboratory instruments are used in research, scientific, drug discovery, and quality control labs, amongst many others in the pharmaceutical, chemical, food and cosmetics industries. METTLER TOLEDO comprehensive industrial solutions cover the various steps in a host of manufacturing processes at many of the same customers that laboratory serves. Solutions range from receiving raw materials through various manufacturing processes, in-line process control and end-of-line packaging control, to logistics and shipping. Increasingly, these solutions are fully integrated into the customer's IT environment, helping automate their workflows. In food retail, our offering for fresh food management ranges from receiving and pre-packaging, to in-store solutions for self-service departments, deli counters, and checkout terminals.