ABSTRACT
The premise of this work is the modification of the properties of chitosan-based film for possible use in food packaging applications. The biofilm was prepared via thermal and mechanical treatment through blending polymers with chitosan using Polyvinyl Alcohol (PVA) and loading different types of chemical agents, i.e., citric acid (CA), succinic acid (SA), and tetraethoxysilane (TEOS). The modification was carried out under high-speed homogenization at elevated temperature to induce physical cross-linkage of chitosan polymer chains without a catalyst. The findings showed that PVA improved the chitosan films' Tensile strength (TS) and elongation at break (Eb). The presence of chemicals caused an increase in the film strength for all samples prepared, in which a 5% w/w of chemical in the optimum composition CS/PVA (75/25) provided the maximum strength, namely, 33.9 MPa, 44.0 MPa, and 41.9 MPa, for CA-5, SA-5, and TEOS-5, respectively. The chemical agents also increased the water contact angles for all tested films, indicating that they promoted hydrophobicity. The chemical structure analysis showed that, by incorporating three types of chemical agents into the CS/PVA blend films, no additional spectral bands were found, indicating that no covalent bonds were formed. The thermal properties showed enhancement in melting peak and degradation temperature of the blend films, compared to those without chemical agents at the optimum composition. The X-ray diffraction patterns exhibited that PVA led to an increasing crystallization tendency in the blend films. The morphological observation proved that no irregularities were detected in CS/PVA blend films, representing high compatibility with both polymers.
ABSTRACT
Community forest development requires a constant supply of high-quality seeds. In addition, sound management of Toona sinensis (surian) seed sources requires a deep understanding of factors affecting seed production. This present study investigated the reproduction characteristics of surian, including flower, fruit and seed productions, variations in the productions of fruits and seeds among trees and among branches, and dendrometric factors that influence the productions of fruits and seeds. Flower production characteristics were observed in 99 panicles, fruit production characteristics were observed in 128 panicles, and seed characteristics were evaluated based on 890 fruits. The number of fruits per panicle ranged from 38 to 646. The number of seeds in fruits ranged from 1 to 35. Fruit size was correlated to the number of filled seeds following a quadratic regression equation. The optimal number of filled seeds was 20 per fruit. Stem diameter, crown width, crown base height, and the number of sub-branches positively influenced the production of panicles per tree, while the crown base height (of the tree) negatively affected the fruit set.
