Every material has a relationship with heat. Yet, thermal behavior can rarely be something you can guess from a chemical formula, maybe possible for a top-notch theorist. But what is the point of guessing if we can heat the material up before our eyes? It turns out that hands-on is just the beginning.
Under heat, some materials fall apart at the first sign of rising temperature, others hold steady until something deep inside gives out. It needs to be measured and understood in the context of a story. A story of why a product failed, why a process stalls, or why a brilliant formulation falls short when scaled.
In this newsletter edition, I will decode the jargon in thermal analysis techniques. Future editions will delve deeper into the essence of each one.
Let's begin.
From Theory to Reality
In school, we learn thermal theory like it’s gospel. Question and answer are one-on-one. We talk about glass transition as a model zig-zag, melting point as a perfect peak, and decomposition as a single step. The curves are clean. The answers, exact. But in practice? Materials don't behave like test questions. The data is messy. The peaks are broad and irregular. Sometimes what looks like noise is the actual clue you’ve been missing.
The first roadblock we face when entering the world of thermal analysis is the jargon. Like many disciplines, jargon seems more formal and professional. But deep down, it is merely a symbol for a technique or a tool that helps us to add context to our story.
I will start in this introductory newsletter by introducing six of the most common thermal analysis techniques. I am also using an imaginary story for each technique to help you get acquainted.
DSC: Differential Scanning Calorimetry
Let's begin by heating a material and monitoring the energy input and output against temperature. Any physical or chemical change—like glass transition, melting, crystallization, and oxidation—in the material will bring about certain changes in the detected signal. This is DSC.
A packaging company noticed that their food wrap film turns brittle during shipment in summer. The supplier claimed the polymer’s glass transition was 75 °C, well above shipping temperatures. DSC reveals an energy output peak well below 75 °C. It turns out that some batch of polymer was not fully cured. A simple DSC test avoided further loss and led to updated processing specs.
TGA: Thermogravimetric Analysis
From the name, we know it has something to do with heat and gravity. It is right. TGA measures weight changes of a material when we heat it up. Plain and simple. When things burn, decompose, or evaporate, TGA captures all of it. Sounds theoretical enough until the story follows.
A product line of flame-retardant panels shows inconsistent performance in fire testing. TGA tells that weight loss profiles vary between units, some with weight loss at lower temperature. Tracing back to the raw material source, the vendor admits that a cheaper additive was used instead, which is the cause of early degradation. TGA analysis in this case forges hard requirements in raw material procurement.
DMA: Dynamic Mechanical Analysis
Dynamic means changing temperature. Mechanical, well, means mechanical. DMA takes a leap and measures how a material wiggles under a controlled force when heated. This behavior it monitors can tell how much and how well a material can store mechanical energy, or instead, dissipate it. Let me elaborate.
Clients complain about excessive noise from the interior panels of an EV. Separate mechanical and thermal tests are all compliant. However, when you run a DMA test—which combines thermal and mechanical—it reveals that the polymer lacks sufficient damping at cabin temperatures which turns vibration into noise.
TMA: Thermomechanical Analysis
Want to know how and if a material expands or shrinks when heated? This is TMA. Even minute changes in dimensions are well captured, critical for delicate material parts that require durability and stability.
Let's run a failure analysis—why something fails—on a delamination issue of a flexible circuit board with TMA layer by layer. The results confirm a mismatch of thermal expansion between the adhesive layer and the substrate. No doubt when temperature increases, the building internal stress is enough to cause layer separation.
LFA: Laser Flash Analysis
The name tells nothing about what it does. Let me rephrase. LFA measures how efficient heat moves through a material. We normally refer to as thermal conductivity and thermal diffusivity. LFA is just the most popular way of measuring it.
All EV batteries need thermal release during operation. We know that. Someone proposes to use a new lightweight composite for the enclosure. Using Laser Flash Analysis, we find that the new material has low thermal diffusivity, too low for rapid heat dissipation from the battery. A follow up formulation idea by adding 10% graphite filler doubled thermal conductivity and the new lightweight battery is in production.
ARC: Accelerating Rate Calorimetry
ARC monitors material self-heating at any temperature. An instrument is made so delicate that it gently heats up a material and then wait under the most extreme heat-isolated condition (an adiabatic process) to see if the temperature even increase one hundredth of a degree over time. This sounds like a tedious process. But in the field of ever more popular lithium ion battery, it often means life or death. Here is an example.
A lithium ion battery supplier wanted to market their new electrolyte with a higher decomposition temperature. A just-in-case ARC test shows a self-heating onset at a temperature even lower than its predecessor. This might be bad news for the R&D team. But it surely saved lives by not having it hit the market.
They work Hand in Hand
Each technique tells a different aspect of the story. Much like a movie scene viewed from different angles and lenses. DSC reveals transitions. TGA shows stability. DMA tells you how a material feels under load. TMA monitors thermal distortion. LFA explains heat flow. ARC predicts danger. But used collectively, they do much more than test. They anticipate performance, explain failures, and guide the path to innovation.
Some of these techniques—DMA and TMA in particular—overlap with mechanical and rheological analysis. Another topic we will be focusing on in the next newsletter edition. When we zoom out and take a God view of all the techniques, it is evident that all of them are interconnected. Our job is to use them to tell a compelling story.
Looking Ahead with TEMPR Learning
Instead of advocating for what the school should do, we will take the lead and just put down what we think is important. I am leveraging the TEMPR Learning platform to teach not just the theory for the sake of it, but the story of reasoning, purpose, and results. If you are in R&D, failure analysis, process engineering, or quality control, my mission is to give you both the technical and storytelling tools to succeed. For the new grads and soon-to-be, I am creating a helping bridge to replace your career dilemma.
Thermal techniques are rarely taught as a whole in school. But they should be, and maybe even blending in the connections beyond the thermal scope. These techniques are seldom used alone in the field. They often work together to guide materials selection, qualify suppliers, solve customer complaints, and keep products safe.
