Effect of vinyl silane modification on thermal and mechanical properties of starch-polyvinyl alcohol blend

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.

Optical Properties and Conductivity of PVA-H3PO4 (Polyvinyl Alcohol-Phosphoric Acid) Film Blend Irradiated by γ-Rays

This study assesses the optical properties and conductivity of PVA–H₃PO₄ (polyvinyl alcohol–phosphoric acid) polymer film blend irradiated by gamma (γ) rays. The PVA–H₃PO₄ polymer film blend was prepared by the solvent-casting method at H₃PO₄ concentrations of 75 v% and 85 v%, and then irradiated up to 25 kGy using γ-rays from the Cobalt-60 isotope source. The optical absorption spectrum was measured using an ultraviolet–visible spectrophotometer over a wavelength range of 200 to 700 nm. It was found that the absorption peaks are in three regions, namely two peaks in the ultraviolet region (310 and 350 nm) and one peak in the visible region (550 nm). The presence of an absorption peak after being exposed to hυ energy indicates a transition of electrons from HOMO to LUMO within the polymer chain. The study of optical absorption shows that the energy band gap (energy gap) depends on the radiation dose and the concentration of H₃PO₄ in the polymer film blend. The optical absorption, absorption edge, and energy gap decrease with increasing H₃PO₄ concentration and radiation dose. The interaction between PVA and H₃PO₄ blend led to an increase in the conductivity of the resulting polymer blend film.

Synthesis of ZnO/SiO2-modified starch-graft-polyacrylate superabsorbent polymer for agricultural application

A bio-based superabsorbent polymer (SAP) for agricultural application was synthesized from modified starch (MS) to enhance its antibacterial property and biodegradability. The starch was modified by zinc oxide and tetraethyl orthosilicate via a sol-gel reaction under an acidic condition. Structural and morphological examinations were used to confirm the modification. The MS showed a good antibacterial activity against Staphylococcus aureus and Escherichia coli with 61.9 % and 99.9 % reduction in viable cells, respectively, after a 1 h exposure. The MS was then graft copolymerized with potassium acrylate monomer to synthesize a new MS-g-polyacrylate (PA) SAP. The grafting reaction was confirmed and the main factors for agricultural applications along with its biodegradation and antibacterial properties were achieved. The MS-g-PA SAP exhibited an excellent reusability and biodegradation. Importantly, the MS-g-PA SAP did not impose growth inhibition of mung bean (Vigna radiata), but provided some transient drought relief.