Typically, when using polymeric rheology modifiers, the viscosity of a formulation decreases with increasing temperature and the polymers can even degrade at higher temperatures. This can cause problems for the manufacturer or user, like instability of the formulation or difficulties in application. Cellulose fibrils and cellulose in general are stable against temperatures up to 200-300 °C, which makes them a good choice when a temperature stable viscosity modifier is needed. Earlier, we have described how you can achieve a stable viscosity in your formulation with cellulose fibrils in the temperature range of 20-90 °C. This time I would like to discuss what happens when we go over 100 °C, either in wet or dry state.
Cellulose fibrils has shown great potential as an oxygen barrier in packaging. This has led to numerous research projects trying to utilize the potential in practice. But how does the fibrils actually create the barrier towards oxygen?
Water holding capacity, or high water retention value, is often mentioned as a key property of cellulose fibrils. When it is dispersed into water, the fibrils trap water between them and do not release it easily. As a consequence, even rather low concentration of MFC in water has gel-like appearance since the water is not able to flow freely. What is behind this? Let’s try to find out.
Plastic microparticles found in the environment have gotten a lot of attention lately. Many of the plastics are very durable and do not degrade in a reasonable time in the nature, although today there are also biodegradable plastics available. Small pieces of plastic can be found almost everywhere on the Earth and it is not fully understood what kind of consequences that could have for the human beings and environment. Therefore, replacing non-biodegradable plastics with biodegradable materials in packaging, clothes and cosmetics has high focus right now. Cellulose fibrils come from wood or other natural resources; are they biodegradable? Can they replace non-biodegradable plastic and reduce the amount of microplastics in the environment?
Governments around the world are pushing industries to reduce their volatile organic compound (VOC) emissions. VOCs include very different type of chemicals but they may be dangerous to human health and therefore there is a common desire to reduce the use of them. Health effects vary from eye, nose and throat irritation to causing cancer.
Microfibrillated cellulose (MFC) differs from many rheology modifiers in that aspect that it can be used in high salinity formulations. The rheology effect comes from entangled fibers and salts do not influence this network as it does when the rheology effect is based on ionic interactions. However, the viscosity and other rheological properties vary slightly as a function of salt concentration. Let’s take a closer look at the reasons behind this.
Three dimensional (3D) printing and tissue engineering are two fields that are currently developing rapidly and are both exciting technologies on their own. What if you combine them? That creates a new manufacturing process, bioprinting. It is a promising technology that might be the key to the on-demand tissue engineering. Microfibrillated cellulose (MFC) or nanocellulosic materials generally have an important role in the development.
Oil recovery with all different operations is a fascinating field for a rheologist since so versatile rheological properties are required in the processes. Microfibrillated cellulose has been recognized as potential green, safe rheology modifier for the oil recovery industry. Why is that?
Making foams, in other words introducing gas in a solid or liquid, is needed in industries like construction, composites, home care and personal care. Solid foam is a clever way to produce lightweight structures and insulation materials, whereas many personal care and detergent formulations are required to form a liquid foam. To produce solid foams, you need a blowing agent which introduces gas bubbles in the solid and a solid (often a polymer) that hardens around them. Liquid foams are mainly created by using surfactants and mixing air in. Earlier on this blog, we have explained how microfibrillated cellulose can be used for creating bubble-free gel coats. Could it also help forming intentional foam structures?
From time to time I get comments from people interested in microfibrillated cellulose (MFC) that they cannot dissolve the product, and the formulation remains hazy no matter how much they mix. Alternatively, they ask how low the concentration needs to be to get a transparent formulation. The answer to these questions is that microfibrillated cellulose does not dissolve in water (or in common solvents) which means that it does not make a transparent solution, no matter how much it is mixed or how low concentration is used. There is no need to worry, however; the non-dissolved fibers are the key factor to the interesting behavior of MFC. Let’s look at the translucency of MFC in more detail.