Thermosetting polymers are widely used in modern industry due to their specific chemical and physical properties. With a wide range of applications, from components of huge aircraft to small electronics, epoxies are one of the main products of the polymers industry. This blog will focus on how these materials are improved and made eco-friendly, by making use of a scanning electron microscope (SEM).
Big steps toward green industry
Eco-sustainability has become key in the industrial advancements of the last few decades. After global warming was assessed as a serious concern, more and more effort was put into limiting the warming process. Being obliged to reduce waste, capture carbon dioxide emissions and improve the efficiency of processes, many industries have invested huge capital in applying a green formula to their business.
In the polymers industry, thermosetting materials require a big consumption of precious and polluting products from oil refineries. Epoxy resins are a typical example of such materials. Despite most of them still being petroleum-based, bioplastics are becoming a very popular raw material for the production of these resins.
This industry conversion not only applies to the resins themselves, but also to the additives that are added to such resins, as a way of improving their resistance to impact or tension.
Industrial sub-products can increase resin performance
It has been proven, for example, that Biochar can boost the tensile strength of epoxy resins as well as their flexibility. Biochar is produced when biomasses are combusted with a controlled amount of oxygen in the atmosphere. Therefore, it is cheap and easily available.
Even more interesting results were achieved when Polypropylene carbonate (PPC), a material produced using carbon dioxide captured from exhaust gases, was used as an additive. An increase of 36% of resistance to impact and 220% higher tensile strength were measured.
Integrating such additives into polymers is not always easy and, especially when the additive particles are very small, it is necessary to verify that the dispersion of particles in the matrix is homogeneous. This inspection requires the sample to be observed with a very high magnification, and this is when scanning electron microscopes (SEMs) come into play.
How SEMs can be applied in the inspection of epoxies
By analyzing the sample with an electron microscope, it is possible to:
Measure the size of the particles;
Evaluate their distribution in the sample;
Determine how they merged with the epoxy matrix;
Perform compositional analysis to track chemical changes that the additives might have been subject to.
The images below show the use of a backscattered electrons detector; the microscope provides an image in which the different levels of contrast highlight the different phases forming the polymer. Other detectors, like a secondary electron detector, can be used to analyze the surface of the epoxy and study its roughness.
Figure 1 & 2: SEM images of epoxy resin and wax. The backscattered electrons image highlights the presence of different phases in the polymeric matrix, providing clear information on their distribution and the general quality of the product.
SEM: Eucentrically-tilting & tensile stages
Modern devices also provide eucentrically-tilting stages, which enable the quantitative measurement of the roughness of samples through stereoscopic 3D reconstructions.
But that is not all: tensile stages — normally used to measure Young’s modulus and other stress-related parameters of materials — have now become so small that they can fit into a desktop scanning electron microscope. This makes it possible to observe the material with a high magnification, while stress is applied to it. Eventually, the causes of the rupture can be observed and investigated, to improve the resistance of the material.
If you would like to know more about the power and possibilities of eucentric tilting stages, our eucentric sample holder information sheet will be of interest to you. It explains — among other things — how the tilting and rotating process works, and how it can help you to achieve higher-quality imaging as a result. Download the free eucentric sample holder information sheet here:
Luigi Raspolini is an Application Engineer at Phenom-World, the world’s leading supplier of desktop scanning electron microscopes. Luigi is constantly looking for new approaches to materials characterization, surface roughness measurements and composition analysis. He is passionate about improving user experiences and demonstrating the best way to image every kind of sample.