Soft Materials Characterization Core Facility Operating Procedures
- What are the Instruments: The Soft Materials Characterization Core Facility is comprised of a Thermogravimetric Analyzer (TGA), Dynamic Scanning Calorimeter (DSC), and Dynamic Mechanical Analyzer (DMA).
How do I use the instruments:
Contact the point-of-contact (POC) by email for the particular instrument you wish to use. Specifically, the POC wants to know:
- what you want to do
- what information you are seeking
- at what temperature, force, etc is the phenomena you are looking for
- what is the material, and what does it react with (specifically Aluminum, steel and Platinum)
- will the material off-gas at temperature and what is the gas (is it reactive or condensable?)
- how many samples.
- Once the POC says that you can use the instrument and what limits are necessary, you will be directed to the superusers to schedule training and/or sample submission. YOU WILL NEED A VALID CORAL ACCOUNT TO DO THIS! We will log you in to verify.
- Once training is complete, schedule time and use the instrument!
- Contact the point-of-contact (POC) by email for the particular instrument you wish to use. Specifically, the POC wants to know:
- Can I submit specimens for analysis rather than get trained: Yes, the POC will decide whether this is allowable (based on how many specimens/ how much time/how difficult). Contact the POC.
- Scheduling: This is done through Coral. However, ½ day a week is reserved for maintenance/calibration by the superusers. Training is usually done at this time.
- How much does it cost: Once trained, each instrument is $7/hr (internal rate) with a maximum charge of 6 hrs in a month (once you hit this level, the instrument is free. This 6 hrs is among all instruments combined). However, each user MUST USE AN INTRUMENT AT LEAST ONCE PER SEMESTER (FALL, SPRING, SUMMER) to maintain certification, or be retrained at the proscribed cost. Training costs are below and are based on the approximate time of training during assisted use – 1 hr for goniometer and 3 hrs for other. For submitted samples the instrument is $55/hr, with a minimum 1 hr of use.
External Submitted Sample
$7/hr ($42/mo max)
- Relevant Personnel:
- Operational limits: This instrument has a range of Room Temp to 1000 C. It only measures mass change and cannot measure heat flow or differential temperature (ie it is not a DTA/SDSC). Only use a reasonable mass of materials – 10-20mg.
- Temperature: Know about what temperature your material loses mass - Only go about ~100 C above the lowest plateau (If there is no reason to go to 1000C then don’t). If you don’t know, then do a reasonable guess and run the material a bit high in temperature to see then adjust subsequent runs. Organic polymers typically are all done below 500 C or so.
- Materials: Know your material – never go close to the boiling temperature. If your material evaporates, then stay WAY below the temperature that it does so. Know what your material reacts with, specifically platinum (There are a variety of platinum eutectics). If you ruin a pan or thermocouple, you will be charged for a new one.
- Evolved gases: Know what your material off-gases – if it degrades to small molecule organics or CO2 (run in air) then it is fine. However, if off-gasses are consensible at room temperature or reactive then it is not allowed. This means that materials such as zinc, mercury, etc cannot be run.
- Provide your own pan: You will be expected to provide your own pan for samples, although we will train you with ours. See below for proper pan size/material, but we can provide with the vendor. They cost ~$400, but are reusable. They must be the proper type for this instrument and undeformed or you will damage the hook and you will pay for that as well.
- Proper Pan: Your material should not be anywhere near the top of the pan – do not overflow. If it is close, use a different pan that holds more. Know if your material shows a eutectic with Pt (P,B, Si, As), in which case use alumina pans and do it in air.
- Proper heating rate: Generally, 20C/minute is ok (for loose powder with space between grains). However, some materials need extra time to heat or evolve gasses – foams, packed powders, and solid materials with residual solvent/liquid may need slower ramp rates. Do not expand, foam, or explode samples in the instrument.
- Cleaning your pan: Only use a blow torch, low pressure air and possibly acid wash to clean the Pt Pan. Never scrape, wire brush, abrade or mechanically clean it. Also, treat the pan gingerly as it is mechanically weak. Deforming the pan can ruin it and damage the instrument!
NOTE: We have an autoloader for a reason –
- Never ever manually load or unload the pan on the hook!
Do not put any material containing the following elements in a platinum pan
- arsenic – even if oxides (use alumina pans instead)
- Only run phosphorous, boron, silicon, or arsenic in air (no other gases allowed).
- Treat the pan with care – do not deform it: If you deform it you will be charged for a new one.
- Never run a deformed pan in the TGA – it could damage the instrument and you will be charged.
- Experiment types: thermal measurement of melting, freezing, and glass transitions, curing point.
- Operational limits: Operational range is determined by the cooling accessory. With LN2 cooling -160°C to 500°C; with Air-Fin cooling room temperature to 700°C. Isothermal experiments above 300°C are not allowed on the LN2 unit.
- Changes to heaters: Only superusers are allowed to switch heating units.
- Required materials: Disposable aluminum pans are provided for users. The Air-Fin cooling system cannot use aluminum pans and users must provide their own sample pans (copper, platinum, graphite, etc. are available from TA Instruments).
- Sample requirements: User samples of mass between 1mg to 30 mg are needed. Best measurement conditions have sample mass of 10 mg to 20 mg. Do not over fill the DSC pans which can ruin the pan press and the DSC sample chamber. Do not allow material to decompose during the DSC run; no off-gassing should occur in DSC chamber. (If your material expands to form a bubble on top of the crimped pan, then it is offgassing too much!) Test your material in the TGA first if these transitions are unknown. If your material reacts with aluminum, then use a more appropriate pan. If a material damages the instrument, you will be charged for repairs
- Machine Settings: Always replace hard cap over sample chamber when experiment is complete. N2 and helium gas should be turned off at end of the experiment.
- Operational limits: The DMA should operate within the limits established below. Data and even the instrument itself can be affected by working out of the operational limits. a. Force Range: 0.0001 – 18 N. Do not use specimen sizes that approach limits (i.e. stay below 5N). b. Temperature Range: -150 to 600 ˚C. Do not use cryogenic or go to 600C if unnecessary. c. Frequency Range: 0.01 to 200 Hz, Data at fringes is difficult to obtain, 0.1-100Hz is recommended. d. Heating/ Cooling Rate: 0.1 to 20 /0.1 to 10 ˚C/min
- Clamp installation: All clamps are composed of two parts: one fixed to be attached to the four mounting DMA posts and a moveable one to be attached to the central drive shaft. When installing clamps (tensile, dual Cantilever, 3-point bend, penetration, submersion, shear) always use the torque wrench below 5-in-lb. when tightening screws. Do not over-tighten screws. Also, always put wrench in straight, never at an angle. Do not forget to remove clamp after use.
- Thermocouples: Avoid touching thermocouples during clamp installation except for submersion clamps, in which thermocouples should be carefully moved to avoid any contact. Contact with the thermocouple tip should be avoided in all cases.
- Clamp Calibration: All clamps (i.e., tensile, dual cantilever, 3-point bend, penetration, submersion) require mass, compliance and zero calibrations after installation.
- Sample Mounting: Initially hand-tighten clamp mounting screws. Always use the torque wrench below 10 in-lb to mount specimens. Do not over-tighten screws. Avoid touching thermocouples during clamp installation.
- Cryogenic Testing: A gas cooling accessory (GCA) introduces cold nitrogen gas in the chamber to test specimens below room temperature. Personal protective equipment should be used when handling cold lines. After GCA installation, specimens can be tested from -150˚C up to 600˚C. DMA can work without GCA installed for testing temperatures ranging from room temperature to 600 ˚C Contact superuser for accessory installment.
- Relative Humidity Control: A chamber is mounted in DMA to control relative humidity (RH) during testing. The accessory is compatible with standard DMA clamps. Avoid touching humidity sensor or thermocouples during sample mounting or clamp installation-calibration. Contact superuser for accessory installment, understanding the following operational limits: a. Relative Humidity Range: 5 to 90% (±3%) b. Temperature Range: 5 to 120 ˚C (±5 ˚C) c. Max Heating/Cooling Rate: 1 ˚C/min
NOTE: Most problems are torque wrench/tightening or thermocouple related – always use the torque wrench, do it properly and never touch the thermocouples!