Monthly Archives: January 2014

Useful AFM Resources

I have spent a lot of time installing AFMs and training customers to work with them.  There were a lot of everyday questions which came up, one of the most popular questions was where to buy supplies.  If you are part of an established lab then you probably are aware of these resources, but if you are setting up a lab or new to the field, then this list is for you.  Of course, you can always purchase supplies from your AFM manufacturer, but there are also third party companies which offer high quality supplies for your needs.    It is helpful to have some useful resources for a quick and easy place to find things.  Otherwise, you can spend countless hours surfing the web.  Some of places I like to purchase supplies are from:

AFM Manufacturers (not a complete list but some of the more prominent companies which have been around)
– AFM Workshop – http://www.afmworkshop.com
Supplies (carbon tape, samples, sample disks, tweezers, cantilevers)
– SPI Instruments http://www.2spi.com
Cantilevers Manufacturers
– Applied Nanostructures – http://www.appnano.com
– Budget Sensors – http://www.budgetsensors.com
– MikroMasch – http://www.spmtips.com
– Nanosensors – http://www.nanosensors.com
– Nanoworld – http://www.nanoworld.com
– VistaProbe – http://www.vistaprobes.com
Cantilever Distributors
Specialty Probes
– CNT Probes – Carbon Design Innovations – http://www.carbondesigninnovations.com
– Diamond Probes – ADProbe – http://www.thindiamond.com/products/nadiaprobes/
– High Aspect Ratio Probes – Team Nanotec – http://www.team-nanotec.de

 

My favorite illustration of thermal analysis

Here is how I like to explain thermal analysis in simple language and graph.

PML_thermalgraph

How about you? How do you explain thermal analysis to others?

*Graph is re-drawn from lecture notes of a short course, “Thermal Analysis for Polymers and Composites: From the Fundamentals to Recent Developments”, July 25-27, 1994, PCL, Seattle, Washington.

Why am I interested in glass transition temperature, Tg?

You are going to hear about glass transition temperature when you work with polymers, be it a thermoplastic or a thermoset or a composite.  Even with non-polymer materials, glass transition can be of importance.  For example, an uncured epoxy mixture (mind you – it is still in the monomer stage, not yet a polymer) typically shows a glass transition below room temperature, aka “sub-Tg”.  Another example, an active pharmaceutical ingredient (API) that exhibits polymorphism, may also show glass transition.

The reason I care about glass transition and glass transition temperature is because Tg can dictate material selection for a specific application.  Above Tg, the material can be described as rubbery or soft or molecularly flexible.  Below Tg, the material is glassy or rigid or molecularly inflexible. For example, elastomers are commonly used above its Tg.  And carbon fiber reinforced plastics (CFRP) in structural applications are commonly used below its Tg.

Another reason I care about Tg is because it gives me insight into molecular structure of the molecule, which also affects material properties.  For example, the glass transition of a phenolic material (a thermoset) can vary due to the extent of cure and crosslinking density.  Another example is the glass transition of a semi-crystalline thermoplastic.  The glass transition can vary due to the degree of crystallinity of the polymer.

These are the main reasons I am interested in Tg.  How about you?  What makes you study and measure Tg of your materials?