Use of Ricinus communis shredded material as filler in rotational molded parts to improve the bio-disintegration behavior

Abstract

This paper focuses on the use of castor oil plant (Ricinus communis) as filler in rotomolded parts using polyethylene (PE) and polylactic acid (PLA) as polymer matrixes. The vegetable shredded material was used in 5 and 10% weight following a dry blending procedure and then rotomolded to obtain cube test parts. This material was characterized to determine its chemical composition, thermal stability, and structure. The NaOH-treated material shows reduced hemicellulose content and higher thermal stability. Obtained composite materials were characterized in terms of mechanical (tensile, flexural, and impact) and thermal properties, morphology, and bio-disintegration behavior. The use of Ricinus as filler in rotomolded PE composite decreases, in general terms, mechanical properties of neat PE, while no significant changes in thermal or bio-disintegration properties are found. On the contrary, PLA composites show higher tensile strength and similar Young's modulus than the matrix, although with reduced flexural and impact properties. Alkali-treated Ricinus material produces parts with higher porosity and thus, lower mechanical properties than composites with untreated material. Finally, the incorporation of this vegetal material modifies to a great extent the thermal properties of the PLA matrix. The bio-disintegration rate increases due to the use of fibers, probably because of the higher moisture absorption of composites.