Water resistance, weight loss and enzymatic degradation of blends starch/polyvinyl alcohol containing SiO2 nanoparticle

Influence of starch silylation on the structures and properties of starch/epoxidized soybean oil-based bioplastics

The present work systematically investigated the influence of starch silylation on the structures and properties of starch/epoxidized soybean oil-based bioplastics. Silylated starch was synthesized using starch particles (SP-ST) or gelatinized starch (SG-ST) under different silane hydrolysis pHs. Due to the appearance of -NH2 groups and lower OH wavenumbers, SP-ST obtained at pH 5 showed higher silylation degree and stronger hydrogen bond interaction with epoxidized soybean oils (ESO) than that at pH 11. The morphology analysis revealed better interfacial compatibility of ESO and SP-ST. The tensile strength of the samples containing SP-ST increased by 51.91 % than the control, emphasizing the enhanced interaction within the bioplastics. However, tensile strength of the bioplastics with SG-ST decreased by 59.56 % due to their high moisture contents from unreacted silanes. Additionally, the bioplastics with SG-ST exhibited an obvious reduction of thermal stability and an increase in water solubility because of the presence of unreacted APMS. The bioplastic degradation was not prevented by starch silylation except high pH. The bioplastics showed the most desirable tensile properties, thermal stability, and water solubility when starch was surface-modified with silanes hydrolyzed at pH 5. These outcomes made the fabricated bioplastics strong candidates for petroleum-based plastics for packaging applications.

Recent trends in polysaccharide-based biodegradable polymers for smart food packaging industry

Artificial packaging materials, such as plastic, can cause significant environmental problems. Thus, the use of polysaccharide-based biodegradable polymers (cellulose, starch, and alginate) has the potential in the field of environmental sustainability, reprocessing, or protection of the environment. Morphological and structural alterations caused by material degradation have a substantial impact on polymer material characteristics. To avoid degradation during storage, it is critical to evaluate and comprehend the structure, characteristics, and behavior of modern bio-based materials for potential food packaging applications. Hence, this review focused on the various types of polysaccharide-based biodegradable polymers (cellulose, starch, and alginate), their properties, and their commercial potential for food packaging applications. In addition, we overviewed the recent development of polysaccharide-based biodegradable polymer (cellulose, starch, and alginate) packaging for food products. The review concluded that the membrane and chromatographics are widely used in production of cellulose, starch, and alginate-based biodegradable polymers. Also, nanotechnology-based food packaging is widely used to improve the properties of cellulose, starch, and alginate biodegradable polymers and the incorporation of active agents to enhance the shelf life of food products. Overall, the review highlighted the potential of cellulose, starch, and alginate biodegradable polymers in the food packaging industry and the need for potential research and development to improve their properties and commercial viability.

Eco-friendly polymer composite films based on waste polyvinyl chloride/sunflower seed cake for antimicrobial and antistatic applications

Purpose

This study aims to get rid of non-degradable polyvinyl chloride (PVC) waste as well as sunflower seed cake (SSC) waste by preparing eco-friendly composites from both in different proportions to reach good mechanical and insulating properties for antimicrobial and antistatic applications.

Design/methodology/approach

Eco-friendly composite films based on waste polyvinylchloride (WPVC) and SSC of concentrations (0, 10, 20, 30 and 40 Wt.%) were prepared using solution casting method. Further, the effect of sunflower seed oil (SSO) on the biophysical properties of the prepared composites is also investigated. Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscope, mechanical, thermal, dielectric properties were assessed. Besides, the antimicrobial and biodegradation tests were also studied.

Findings

The crystallinity increases by rising SSC concentration as revealed by XRD results. Additionally, the permittivity (ε′) increases by increasing SSC filler and SSO as well. A remarkable increase in dc conductivity was attained after the addition of SSO. While raw WPVC has very low bacterial activity. The composite films are found to be very effective against staphylococcus epidermidis, staphylococcus aureus bacteria and against candida albicans as well. On the other hand, the weight loss of WPVC increases by adding of SSC and SSO, as disclosed by biodegradation studies.

Originality/value

The study aims to reach the optimum method for safe and beneficial disposal of PVC waste as well as SSC for antistatic and antimicrobial application.

Synthesis and Characterization of Konjac Glucomannan/Carrageenan/Nano-silica Films for the Preservation of Postharvest White Mushrooms

In this study, the konjac glucomannan (KGM)/carrageenan (KC)/nano-silica film was prepared and characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The preservation quality of white mushrooms (Agaricus bisporus) packed using the films was also determined. The nano-silica dosage was found to affect the properties of the nanocomposite KGM/KC films. The results indicated that the properties of the films were significantly improved with the addition of nano-silica. The water vapor permeability, water solubility, moisture absorption, and light transmittance of KGM/KC/nano-silica films were significantly affected by the nano-silica dosage. In this study, the optimal nano-silica dosage to incorporate into the film in order to achieve excellent performance was 0.3%. Strong intermolecular hydrogen bonds were also observed between KGM/KC and nano-silica in the KGM/KC/nano-silica film by FTIR. In addition, the KGM/KC/nano-silica film markedly reduced the browning index, delayed the weight loss and softening, and extended the shelf life of mushrooms during storage at 4 °C. The KGM/KC film modified using nano-silica can provide a potential method for improving the preservation quality of white mushrooms during storage.

Biodegradation behaviors and water adsorption of poly(vinyl alcohol)/starch/carboxymethyl cellulose/clay nanocomposites

The focus of this work is to study the effect of sodium montmorillonite (MMT-Na) clay content on the rate and extent of enzymatic hydrolysis polyvinyl alcohol (PVA)/starch (S)/carboxymethyl cellulose (CMC) blends using enzyme cellulase. The rate of glucose production from each nanocomposite substrates was most rapid for the substrate without MMT-Na and decreased with the addition of MMT-Na for PVA/S/CMC blend (51.5 μg/ml h), PVA/S/CMC/1% MMT (45.4 μg/ml h), PVA/S/CMC/3% MMT (42.8 μg/ml h), and PVA/S/CMC/5% MMT (39.2 μg/ml h). The results of this study have revealed that films with MMT-Na content at 5 wt.% exhibited a significantly reduced rate and extent of hydrolysis. Enzymatic degradation behavior of MMT-Na containing nanocomposites of PVA/S/CMC was based on the determinations of weight loss and the reducing sugars. The degraded residues have been characterized by various analytical techniques, such as Fourier transform infrared spectroscopy, scanning electronic microscopy, and UV-vis spectroscopy.

Polyvinyl alcohol:starch:carboxymethyl cellulose containing sodium montmorillonite clay blends; mechanical properties and biodegradation behavior

The focuses of this study were to investigate the effect of sodium montmorillonite clay (MMT-Na) content on the physical properties and extent of enzymatic hydrolysis Polyvinyl Alcohol (PVA): Starch (S): Carboxymethyl Cellulose (CMC) nanocomposites using enzyme <alpha>−amylase. The results of this work have revealed that films with MMT-Na content at 5 wt% exhibited a significantly reduced rate and extent of starch hydrolysis. The results suggest that this may have been attributed to interactions between PVA:S:CMC and MMT-Na that further prevented enzymatic attack on the remaining starch phases within the blend. The total solids that remained after 4320 min were 65.46 wt% (PVA:S:CMC); 67.91 wt% (PVA:S:CMC:1% MMT-Na); 78.43 wt% (PVA:S:CMC:3% MMT-Na); 80.24 wt% (PVA:S:CMC:5% MMT-Na). The rate of glucose production from each nanocomposite substrates were decresed significantly as the MMT-Na percentage increased from 0 to 5% (W/W). At the level of 5% (W/W) MMT-Na, the films showed the lowest rate of glucose production values (18.95 μg/ml h). With the increase of the MMT concentration from 0 to 5%, the UTS increased 5 from 18.36 to 20.38 MPa, however, the strain to break (SB) decreased noticeably from 35.56 to 5.22%.

Study of enzymatic degradation and water absorption of composites carboxymethyl cellulose and poly (ϵ-caprolactone) containing SiO2nanoparticle by cellulase

This study investigates the effect of Poly (ϵ-Caprolactone (PCL) and Nano-SiO2content within the Carboxymethyl Cellulose (CMC) blends on the rate and extent of carboxymethyl cellulose enzymatic hydrolysis using the enzyme cellulase. The results reveal that blends with Nano-SiO2content at 5 wt% exhibit a significantly reduced rate and extent of CMC hydrolysis. This may be attributed to interactions between CMC and SiO2that prevent further enzymatic attack on the remaining CMC phases within the blend. The total solids that remained after 2880 min were 44.8 wt.% (CMC: PCL); 62.7 wt.% (CMC: PCL: 1% Nano-SiO2); 69.8 wt.% (CMC: PCL: 3% Nano-SiO2); 73.1 wt.% (CMC: PCL: 5% Nano-SiO2). Enzymatic degradation behaviour of CMC: PCL: Nano-SiO2was based on the determinations of water resistance, weight loss and the reducing sugars. The degraded residues have been examined by scanning electronic microscopy (SEM) and UV-Vis spectroscopy.