Hybrid Biocomposites with Starch Derived Nanoparticles and Cellulose Fibers

Abstract

The use of natural polymers such as starch and cellulose in composites has gained significant popularity due to two main reasons: i) biopolymers increase the ratio of biodegradable and renewable content in most fossil-based polymer matrix composites and ii) their low density and high specific strength allows for a multitude of tailored material properties which can cater to industries such as automotive, biomedical and food packaging, construction etc. The purpose of this work was to evaluate composites the use of cellulose fibers, starch granules and novel starch-based biopolymer nanoparticles as fillers in polyolefins matrices and to investigate their mechanical and thermal properties. Several formulations were prepared and evaluated in order to further understand the effect of these fillers and matrices. Two types of cellulose fibers were used, regular ground cellulose pulp and Cellulose Fiber Type 2 pulp. Two grades of linear low-density polyethylene (LLDPE) and one grade of polypropylene (PP) were used as matrices and two types of native starch granules and two grades of amorphous starch-based biopolymer nanoparticles were used. The aim of this research was to determine individual and synergistic effect of formulation components on the mechanical properties, with special attention to flexural modulus, flexural strength and impact strength. The effect of filler on the polymer flow was evaluated by measuring melt flow index (MFI). The thermal properties were evaluated by measuring glass transition and melting temperatures. The effect of the fillers on the crystallinity was also measured. The morphology was studied using microscopy (SEM) and crystallinity of composites measured by X-ray diffraction (XRD) and calorimetry (DSC).