Development of pcl/date palm fiber biocomposites for sustainable packaging applications: effects of dry blending process on bio-composites’ mechanical and thermal performances

Polycaprolactone (PCL)/date palm fiber (DPF) reinforced fully bio-degradable composites were developed for sustainable packaging applications. A comprehensive literature review was conducted in order to understand and present the current research scenario of the use of date palm fiber-based bio-composites in sustainable packaging applications. Dry blending process was applied to mix polymer and fibers for producing their bio-composites, using the compression moulding technique and investigated the effects of dry blending process on composites’ mechanical and thermal properties. These properties were compared with the melt-blended PCL/DPF composites’ properties found in the available published literature. In a melt blending process, polymer matrix is melted, and fiber contents are blended in the polymer matrix, employing a high shear pressure and heating temperature using an extrusion machine, whereas,
in a dry blending process, polymer and fiber contents are mixed manually or in a shear mixer without application of heating or melting. In this work, the dry blended PCL/DPF bio-composites were produced by mixing fibers at various concentrations (2.5-10%, w/w) in the main PCL polymer matrix. The distribution of fibers in the polymer matrix was evaluated using SEM images. Mechanical properties were characterized with tensile tests, while thermal and thermomechanical properties were tested with DSC, TGA and DMA processes respectively. In addition to these, water contact angle measurement was also done to understand the surface properties of developed bio-composites in response to water absorption affinity. Despite melt blending process being popular and considered to have better mixing capability compared to the dry blending process, polymer and fibers can be degraded during the application of high temperature and pressure in the extrusion process. In addition to this, the melt blending process requires time, high process energy consumption and initial equipment investment. In this work, the dry-blending was able to produce PCL-DPF bio-composites successfully where the dry-blended bio-composites
showed similar mechanical properties to melt-blended PCL-DPF bio-composites found in the existing literature. Therefore, this dry-blending technique can be further explored as a suitable potential alternative to produce bio-composites and use this technique more frequently in the industrial sector.