Recycling dyed cotton textile byproduct fibers as polypropylene reinforcement

The textile industry generates a large amount of byproducts that must be treated before being recycled or disposed of. The treatments to extract the dyeing agents are mandatory, and involve costs and interaction with toxic reagents. A relevant amount of such byproducts are short cotton dyed fibers. Cotton fibers are high-quality cellulosic fibers and can be used as composite reinforcement. In this paper, dyed cotton fibers were used to formulate, obtain and tensile test composite materials. The impact of the presence of dyes was studied and such dyes enhanced the interphase between the matrix and the reinforcement. On the other hand, when a coupling agent was incorporated to the formulation of the composites, the dyes hindered the chemical interactions between the maleic acid and the OH groups of the cellulosic fibers. Nonetheless, the composite materials showed competitive mechanical properties that were better than other natural fiber-reinforced composites and comparable to some glass fiber-based ones. Dyed cotton fibers can be used as reinforcement without further treatment, increasing the value chain of the textile industry and decreasing the chemical treatments necessary to recycle or dispose of dyed textile fibers.