Plastic is an incredibly versatile and widely used material, integral to countless everyday items. However, its durability, longevity, and low cost have contributed to a significant plastic disposal and sustainability challenge. Addressing this issue requires innovative solutions in recycling and the development of new plastics that are easier to recycle, such as bioplastics.
For manufacturers, staying relevant in this evolving landscape means embracing advancements. Recycling bioplastics is a relatively new trend that has gained significant momentum in recent years. Advances in chemical recycling and depolymerization processes are transforming the industry, making it possible to recycle plastics more efficiently and effectively.
Material analysis plays a crucial role in these efforts by ensuring that both bioplastics and recycled plastics meet the necessary performance standards for their intended applications. Through rigorous testing and quality assurance, manufacturers can ensure their products are both sustainable and high-quality, driving the transition towards a more sustainable plastic lifecycle.
With over 35% of primary use plastic dedicated to packaging, numerous long-standing legislations focus specifically on this area. The EU's Packaging Directive 94/62/EC, for example, sets clear requirements for all packaging on the market. These include minimizing weight and volume, as well as minimizing their content in hazardous substances, and ensuring packaging is reusable or recyclable whenever possible.
As part of the EU’s Green Deal to move towards a circular economy, Regulation (EU) 2022/1616 focuses on food packaging and the safety of recycled plastics. This regulation mandates that plastic packaging recovered from household collections can only be reused for food if it has been purified using appropriate or novel technology.
To understand where material analysis can help overcome these kinds of challenges in recycling, it’s worth looking at the plastics lifecycle.
As shown in the diagram, plastics originate from crude oil or natural gas, with new sources including recycled plastic monomers and vegetal materials. They are processed to acquire specific properties for end products like food packaging, clothing, or electronics. After use, these products can be repaired, reused, recycled, or sent to landfill.
Fortunately recycling of plastics is very much on the increase. This can take two different routes. In mechanical recycling, plastics are made into new products without altering their chemical structure. The other method is chemical recycling, where the plastics are broken down into their monomer building blocks and new polymers are created for feedstock. Another use for plastics at the end-of-life stage is for energy recovery, where the plastic is incinerated and the resulting energy used to power turbines to produce electricity.
Bioplastics refer to plastic type materials that are made from renewable biomass sources, usually plants, such as sugarcane or corn. The first step in the lifecycle is sourcing these raw materials. Secondly, the starches are extracted and then formed into monomers or polymers using bacteria or through fermentation. Like standard plastic, the next stage of extrusion and adding various compounds ensure the bioplastic has the right properties for its end use.
After use, since it is usually biodegradable, the bioplastic can be added to landfill where it may break down back into the soil or be composted where the nutrients can be made available for new plant growth, thereby completing the cycle.
Thermal analysis (TA) and energy dispersive X-ray fluorescence (XRF) are used at various stages of the plastic and bioplastic lifecycle to facilitate the use of recycled plastics.
Plastic produced from oil or natural gas undergoes polymerization, relying heavily on catalysts to accelerate and complete the reaction. XRF analysis can check for the presence of these catalysts in the base polymer and determine whether all the material has reacted. This will tell you whether the product is safe to use and help optimize the process control parameters.
TA is extremely useful in raw material identification – both for virgin polymers and recycled plastics. You can determine which polymers are present in the pellets you receive from your supplier and check whether there are any impurities present. Differential Scanning Calorimetry (DSC) can determine the melting points of raw materials, identifying the polymers present and their concentrations. This is particularly useful when working with recycled plastics.
The base polymer – whether traditional plastic or bioplastic – usually requires the addition of chemicals to help with the manufacturing process and ensure the end product exhibits the correct properties. XRF is a critical technique in this stage, capable of measuring a wide range of elements down to parts per million (ppm) levels. This ensures that the product meets stringent specifications by accurately quantifying the concentration of additives and fillers. Additionally, STA is often employed for additive quantification. When combined with instruments such as FTIR, MS, and GCMS, STA can also identify additives without the need for sample preparation.
Scanning Electron Microscopy (SEM) is another vital analysis tool used during production. SEM can study particle size, shape, and the distribution of additives within the polymer matrix. This detailed analysis helps manufacturers optimize the polymer mix, ensuring uniformity and enhancing the material's performance.
XRF is also useful at all stages of the plastic lifecycle to check that raw material or finished products comply with health and safety legislation, such as the RoHS directive or the Halogen-Free IEC standard. For example, XRF can check for the presence of chlorine in finished products and the presence of bromine in polystyrene waste.
Phthalate screening can be done with thermal desorption mass spectrometers (such as the Hitachi HM1000A benchtop analyzer) to determine the total amount of phthalates within a sample.
In addition to XRF being used to detect the presence of harmful substances at the recycling stage, TA can also detect and identify potential impurities within waste polymers and rubbers. Both DSC and thermogravimetric analysis (TGA) can be used to determine base polymer type, identify impurities, and check material characteristics.
While not directly part of the lifecycle, material analysis plays a crucial role in accelerating the development of new materials. For instance, thermal analysis can be used to create innovative bioplastic formulations, discover new blends incorporating recycled polymers, or test the effects of various additives. These capabilities enable manufacturers to develop high-performance, sustainable materials more efficiently, driving innovation in the plastics industry.
Ensuring the stability and mechanical properties of the final product is essential for its performance and durability. Techniques such as Dynamic Mechanical Analysis (DMA), Thermomechanical Analysis (TMA), and Universal Testing Machines (UTM) are used to evaluate the mechanical properties of plastics, including, stiffness, modulus, tensile strength, thermal expansion, elasticity, and impact resistance. These tests help verify that the final product meets the required standards and can withstand the intended application conditions.
See the resources below for more insight into using material analysis within plastic / polymer production and recycling.
Webinar: Expert tips for using material analyzers in plastic production QA / QC.
Blog: Using XRF for rapid quality control in polymer-based manufacturing
Blog: Polymer recycling and reuse with thermal analysis
