Microalgal biomass as renewable biofiller in natural rubber compounds

• Published in: Polymer bulletin (Berlin, Germany) Germany), 2022-10, Vol.79 (10), p.8927-8946
• Main Authors: Bellinetto, Emanuela, Ciapponi, Riccardo, Contino, Marco, Marano, Claudia, Turri, Stefano
• Format: Article
• Language: English
• Subjects: Algae; Biomass; Carbon black; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Crystallization; Cyanobacteria; Dynamic mechanical analysis; Fracture testing; Fracture toughness; Mechanical tests; Morphology; Natural rubber; Organic Chemistry; Original Paper; Physical Chemistry; Polymer Sciences; Pressure molding; Proteins; Rubber; Soft and Granular Matter; Strain; Tensile strength; Tensile tests; Thermal analysis; Thermal stability; Thermogravimetric analysis; Vulcanization; Zinc oxides
• ISSN: 0170-0839; 1436-2449
• DOI: 10.1007/s00289-021-03935-z

Microalgal biomasses, consisting of micronized Spirulina Platensis and its low protein fraction, were investigated in this work as possible renewable biofillers in natural rubber compounds, with the aim of replacing the commonly used carbon black. Natural rubber, in some cases blended with 10% of epoxidized natural rubber to improve the matrix-filler affinity, was compounded with 25, 35, 50 and 75 phr of each biomass. Compounds with 25, 35 and 50 phr of carbon black N990 were also prepared as benchmarks. After compounding, vulcanization times were determined by dynamic mechanical analysis. Rubbers were vulcanized by compression moulding and characterized by means of morphological analysis (scanning electron microscopy), thermal analysis (thermogravimetric analysis, dynamic mechanical thermal analysis) and mechanical tests (tensile tests, strain induced crystallization detection by X-ray diffraction, pure shear fracture tests). Microalgal biomass turned out to be homogeneously dispersed in natural rubber matrix and the materials obtained required lower curing times compared to carbon black compounds. It was found that, up to 50 phr, Spirulina has the ability to increase rubber tensile strength and modulus, acting similarly to N990, while decreasing rubber thermal stability and fracture toughness.