Cassava Starch Biocomposites Research Articles

Comparative analyses of rice husk cellulose fiber and kaolin particulate reinforced thermoplastic cassava starch biocomposites using the solution casting technique

AbstractThe potential of biodegradable packaging materials from thermoplastic cassava starch (TPS) reinforced with rice husk cellulose fibers (RHCF) and kaolin particulates (KP) using the solution casting method has been presented. This involved the blending of TPS and RHCF/KP in a plasticizer of ~4 ml of glycerol and ~45 ml of distilled water at 125°C and stirred at 60 rpm until a gel was formed. The gel was cast into sheets and bone‐shaped tensile specimens and allowed to dry for 5 days and characterized. The results show a semicrystalline structure for TPS with an ~36% increase in crystallinity after reinforcement. The O‐H bond stretching and the C‐H bending bonds due to starch–glycerol reactions were the common functional groups in TPS–RHCF biocomposites, and Si‐O‐C bonds were characteristics of the silica phase in the kaolin. The water vapor transmission rate (WVTR) reduced to ~34% with KP reinforcements from ~238 g/m.day to 177 g/m.day and to ~74 g/m.day and ~164% for TPS–RHCF. The strength increased with up to 50 wt% kaolin content; ~0.96 MPa yield strength and ~2.60 MPa ultimate tensile strength (UTS) were recorded. For the RHCF reinforced composites, TPS‐50 wt% also showed high strengths of ~0.96 MPa yield strength and ~3.50 MPa UTS. The WVTR reduced as content of kaolin was increased. Typically, from 0 to 30 wt% volume fraction of kaolin, the WVTR was reduced by ~34% to 177 g/m.day for TPS–kaolin and by ~164% to ~74 g/m.day in TPS–RHCF. The as‐prepared biocomposites have potential as good packaging materials.

Effect of filler and sonication time on the performance of brown alga (Sargassum plagiophyllum) filled cassava starch biocomposites

A biocomposite was prepared from a mixture of pre-gelatinized cassava starch and a brown alga (Sargassum plagiophyllum) as a potential alternative material to synthetic plastic. The brown alga was ground using a planetary ball mill and its morphology was characterized and particle size determined. Mixtures of starch and milled brown algae were sonicated to improve dispersion of the algae in the starch matrix. Biocomposites of starch and milled brown algae were prepared using compression molding. The effects of milled brown algae content and sonication time on the properties of the obtained starch-based biocomposites were investigated. The biocomposite with the highest tensile strength (2.22 MPa) and the lowest weight loss after accelerated weathering for 24 h (20.65%) was from a mixture of starch and 10 wt% milled brown algae sonicated for 120 s. These results were consistent with the good dispersion and adhesion of the milled brown algae in the starch matrix as revealed by scanning electron microscopy (SEM) images. Stress transfer in this biocomposite was more effective and photo-degradation and hydrolytic degradation were inhibited. Thermogravimetric analysis (TGA) results showed that the addition of 10 wt% of milled brown algae and sonication for 120 s also improved the thermal stability of the obtained biocomposite.

Physicochemical Analysis of Graphene Oxide-Reinforced Cassava Starch Biocomposites

Despite the proven application of cassava starch as biocomposites, the starch still has several drawbacks in physical and mechanical properties that need to improve to ensure its commercialization in the future. Thus, in this study, the modification of cassava starch-based (CP) properties was made by adding graphene oxide (GO) filler into cassava starch solution via starch intercalation method. Several physicochemical analyses were performed using Fourier-Transform Infrared (FTIR) Spectrometer and Scanning Electron Microscopy (SEM). The effects of GO content in different concentrations to the mechanical, water uptake, biodegradation, and fungi observation under the microscope were also determined. FTIR spectra of GO-reinforced cassava exhibited all significant peaks from CP and GO present. SEM images show an irregular texture and layered structure of GO. The biocomposites produced from 10% GO (C10) has superior properties with a tensile strength of 1.60 MPa, Young Modulus of 189 MPa, and elongation at a break of 2.88 mm. The decrease of residual weight and water uptake percentages at higher concentrations of GO elucidate the biocomposites' enhanced properties. The improved resistance against fungus also resulted from the incorporation of GO into the cassava starch matrix.

Influence of grape and acerola residues on the antioxidant, physicochemical and mechanical properties of cassava starch biocomposites

The aim of this work was to develop cassava starch biocomposites with varius concentrations of grape skin (Gr) and acerola (Ac) residues (0.1, 1.0, 5.0 and 10.0 wt%) using extrusion and injection molding processes. Grape residue had the highest concentration of total monomeric anthocyanin (ANC) and Ac had the highest concentration of total phenolic content (TPC) and total sugars. The starch and fruit residues had thermal degradation onset temperatures above the processing temperature profile of polymer biocomposites. The results showed that the antioxidant, physicochemical, mechanical, and morphological properties of these biocomposites were influenced by the type and concentration of the fruit residues. The addition of grape skins and acerola residues to the cassava thermoplastic starch resulted in better antioxidant characteristics, indicating the potential of these formulations for the development of new bioactive packaging obtained by large-scale processes.

Structure-properties relationships in alkaline treated rice husk reinforced thermoplastic cassava starch biocomposites

The study focuses on structure-properties relationships in thermoplastic cassava starch (TPS) based biocomposites comprising 5–20 wt% of untreated and treated rice husk (RH). Alkaline treatment with 11% w/v NaOH removed the hemicellulose layer of RH as confirmed by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), and resulted in a larger population of –OH groups exposing on the fibril surface. Consequently, the filler-matrix interactions between treated RH and TPS were enhanced, although Brunauer-Emmett-Teller (BET) surface area analysis indicated that the surface area of treated RH was not increased. Interestingly, the biocomposites contained 20 wt% treated RH showed substantially improved tensile strength by a factor of 220% compared to the neat TPS. The biocomposite at 15 wt% treated RH showed high water absorption. TPS with all treated RH contents showed high biodegradation rate, while the thermal stability of the TPS/treated RH biocomposites was slightly decreased. These novel composites showed promising properties for applications as absorbents.

Characterization of PVA/cassava starch biocomposites fabricated with and without sonication using bacterial cellulose fiber loadings

This paper reports the characterization of polyvinyl alcohol (PVA)/cassava starch biocomposites. The cassava starch gel with or without ultrasonic probe treatment was mixed with PVA gel then short bacterial cellulose fibers were added. The presence of the sonicated starch gel in the PVA resulted in low thermal and moisture resistance, and low transparency of the blend film. After adding the fibers thermal and moisture resistance of the sonicated biocomposite increased due to stronger hydrogen bonding between the fibers and the matrix. Tensile strength of sonicated biocomposite with 10 g fibers increased 215% compared to the sonicated blend. However, addition of the fibers to the non-sonicated blend did not significantly increase mechanical and thermal properties or moisture resistance of the biocomposite. Opacity of the non-sonicated biocomposite was lower than that of the sonicated one.

Cassava starch biocomposites reinforced with cellulose nanocrystals from kenaf fibers

This study highlights the potential of cellulose nanocrystals (CNCs) from kenaf fibers as reinforcing fillers in starch-based biocomposites. By hydrolyzing kenaf fibers with 65 wt.% sulfuric acid, CNCs with diameters of 12 ± 3.4 nm were obtained. Cassava starch biocomposites were prepared using a solution casting method which includes 0–10 wt.% kenaf CNCs as fillers and glycerol/sorbitol (ratio of 50:50) as plasticizer. The composites were characterized by different techniques, including tensile tests, thermal stability tests, transmission electron microscopy, field emission scanning electron microscopy (FE-SEM), water uptake tests, and observation of the physical properties of the film cast. The CNCs appeared as white, shiny dots under FE-SEM with a good dispersion of the nanofillers within the starchy matrix. The tensile strength and modulus of the biocomposite films were significantly enhanced when compared to unfilled starch films. Transparent, thin, and flexible films were obtained from both the plain matrix and 6 wt.% CNC biocomposites, confirming that CNCs may be used as fillers without affecting the composite’s transparency. Furthermore, incorporation of CNCs in the plasticized matrix led to a decrease in water sensitivity.

Preparation and Characterizations of Cassava Starch Nanocomposite Reinforced Kenaf

The aim of this research is to prepare biodegradable plastics which are made from the natural materials. In this study, solution casting technique is used to prepare the cassava starch nanocomposite reinforced kenaf. Prior to that, kenaf fibers undergo alkali and bleaching treatments in order to prepare the cellulose. Nanocellulose which used as reinforcing nanoparticle in the composites was then prepared by acid hydrolysis of obtained cellulose with 65% sulphuric acid. The preparation of cassava starch biocomposites was done using the mixture of sorbitol/glycerol (1:1) with various cellulose loading (0%, 2%, 4%, 6%, 8% and 10%). Finer size of cellulose is examined from the transmissions electron microscopy (TEM) analysis with diameter of 12±3.04 nm and length of 70-190 nm recorded. As for field emission scanning electron microscope (FESEM) analysis, good dispersion and strong interaction between starch and cellulose had been observed for the nanocomposite films. These contribute for enhancement in the mechanical performance which demonstrated improvement of all nanocomposite films compared to the neat matrix with 6 % cellulose composition showed the highest tensile stress value of 6.3 MPa.