Intrinsic viscosity has been a parameter commonly used in the waste and recycle process. Based on a recently published article on Engineer Live, about 46% of waste in the oceans have been directed to fishing nets. On top of recycle programs and efforts to reduce the amount of waste, a company called Plastix A/S uses methods to reduce viscosity of the fishing nets which are mainly polyethylene (HDPE). Using compatible polymers, industry developers have been reviewing the potential to use various polymer dynamics to deter a continuous use of material into a method of cycled reuse.
Polymer blends can be either miscible or immiscible. The properties are affected depending on the nature of the blend. The hypothesis is that by blending, the final product will show additive properties regarding viscosity, an improvement over the initial recycled polymer.
If the blend is not miscible, this does not mean it is not compatible. Miscibility is a measure of mixing at the molecular level. An immiscible blend can still be compatible if it still shows good macroscopic physical properties, which arise from strong interactions between the component polymers. These concepts are far easier to consider when the correct classification is given for the materials in question.
The results of compounding recycled fishing nets with virgin HDPE showed that another important variable is the blend ratio, as this further determines the properties of the material. The best overall results are 50/50.
The strength of the recycled material is maintained and the processability conditions are improved. Nevertheless, these results were obtained at selective compounding conditions and without any additives. The next steps are to carry out the same process under different conditions, in order to create a robust database of blends and their properties.
It is important to consider that when designing a product, it must exhibit a desired performance at a specific cost. The material and the manufacturing technique, as well as sustainability issues and the post-consumer life, must be considered. Fishing nets make an attractive possibility as a resource of HDPE for industry.
To achieve that, the development of responsible material handling will simplify this complex question for material engineers. When the material is well understood, from manufacture, throughout its life, and its disposal, the option of predicting its behaviour when recycled becomes easier.
Nevertheless, the continuous research of polymer molecular dynamics opens the door for the understanding of the performance limits of polymers, and ways to recover them to become part of a cycle instead of a linear chain of consumption."