Now showing 1 - 2 of 2
  • Publication
    Processing, tensile and morphological characteristics of polylactic acid/ Chitosan biocomposites prepared by melt compounding technique
    Biodegradable polymers of polylactic acid (PLA) and chitosan (Cs) has a great potential as alternative candidates to replace conventional synthetic plastic apart to reduce the plastic waste pollution due to the unique properties of superior mechanical strength, feasible processability and rapid degradation. In this work, PLA/Cs biocomposites were prepared via melt compounding and compression moulding techniques in the absence of any plasticizer and additive. The effect of chitosan loading (2.5, 5, 7.5, 10 php) on processing, tensile and morphological characteristics of PLA/Cs were evaluated using internal mixer, universal testing machine and field emission scanning electron microscopy (FESEM), respectively. Processing characteristic indicates PLA/Cs biocomposites demonstrated higher processing torque in comparison to neat PLA due to the increase in melt viscosity and decrease in chain mobility of the polymeric materials. Tensile test results revealed that the maximum strength (54.60 ± 0.51 MPa) and tensile elastic modulus (2.67 ± 0.01 GPa) was attained by PLA/2.5Cs biocomposite. In fact, the addition of chitosan content up to 10 php results in significant decreased in tensile strength and elongation at break of 23.38 ± 0.37 MPa and 0.96 ± 0.04 %, respectively. This is supported by the electron micrograph observation of the PLA/2.5Cs tensile fractured surfaces that exhibits uniform dispersion and good interfacial adhesion between chitosan and PLA matrix which signifies higher tensile properties. However, more agglomeration and poor filler-matrix interaction was observed with further addition of chitosan content of above 7.5 php which implies deterioration in tensile properties. The results suggest that the incorporation of low chitosan loading improve the processing, tensile and polymer compatibility in PLA/Cs biocomposites.
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  • Publication
    Cellulose nanocrystals from bleached rice straw pulp: acidic deep eutectic solvent versus sulphuric acid hydrolyses
    The present work aims to investigate the feasibility of oxalic acid-choline chloride deep eutectic solvent (OA-ChCl DES), which serves as a promising green solvent that utilized in the acidic deep eutectic solvent (DES) hydrolysis. Oxalic acid-choline chloride DES cellulose nanocrystal (OA-ChCl DES CNC) was isolated from the bleached DES treated pulp (BP) through the acidic DES hydrolysis using 1:1 molar ratio of OA-ChCl DES. The functional groups, crystallinity index, morphological structure, particle size, zeta potential, thermal stability and surface chemistry of the OA-ChCl DES CNC were compared with the sulphuric acid cellulose nanocrystal (SA-CNC) that prepared via sulphuric acid hydrolysis. The findings revealed the presence of negatively charged carboxyl groups on OA-ChCl DES CNC surface after the acidic DES hydrolysis. The physicochemical analyses verified that the OA-ChCl DES CNC was in nano-sized range with polydispersity index (PdI) of 0.56, indicating slightly monodispersed nanoparticles. A stable OA-ChCl DES CNC colloidal suspension with zeta potential value of −52.1 ± 5.2 mV was obtained. The OA-ChCl DES CNC outweighed the SA-CNC in term of thermal stability (288 °C) despite having a slightly lower crystallinity index (76.7%). In fact, the OA-ChCl DES CNC with a yield of 55.1% was achieved through the acidic DES hydrolysis, suggesting that the OA-ChCl DES was capable of promoting efficient cleavage of strong hydrogen bonds in BP. Graphic abstract: [Figure not available: see fulltext.]
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