Carbon Blacks
Carbon blacks are widely used as fillers and pigments and are almost exclusively derived from nonsustainable sources, mainly fuel oils, today. Technically there is no reason that they could not be produced from more sustainable raw materials, such as vegetable oils, and there has already been some work along these lines for the tire industry; this may develop as a commercial option in the future. Another option for improving sustainability would be to produce carbon blacks from the oils obtained by end of life tire pyrolysis. It is also perfectly possible to produce carbon blacks from natural gas, and this process can coproduce hydrogen for use as a clean fuel. This approach is starting to be exploited commercially by companies such as Monolith Technologies (http://monolithmaterials.com).
Use of Particulate Fillers to Improve Sustainability
In a breakout development, Imerys has shown that mineral fillers can be used as compatibalizing agents for mixed polymer recyclate. Based on this, they recently commercialized ImerPlast™, a compatibalized, mixed polymer compound consisting of recycled polyethylene and polypropylene resin and a mineral-based compatibalizing agent. (http://www.imerplast.com/)
According to the company, ImerPlast™ extends the number of useful applications for recycled plastic feedstock, allowing a higher recycling rate and increasing the number of uses for recycled polymers. They say that just 6 out of the 25 million tons of plastic waste generated in Europe are currently recycled. Material recycling facilities collect plastic waste and resell the easily sorted major fractions, such as bottles, to recyclers. The remainder, usually only sorted by density, is mixed polymer and often mixed color, which until now has had little value and few applications. While mixed polyolefins have been used for some time in certain injection molding applications, phase separation, especially in slow cooling applications, has been a barrier for their use in extrusion. This is because polypropylene and polyethylene are not miscible. If fed together into an extruder manufacturing products such as pipes, phase separation happens and breaks or holes can occur. ImerPlast™-engineered mineral overcomes phase separation and ensures stable production.
