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20192
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Subject: Natural Resources Management × Author: KAU × End date: 2019 × Start date: 2010 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Development and Characterization of natural gum base Nanocomposite
    (Department of Natural Resource Management, College of Forestry, Vellanikkara, 2019) Meghana Rose, Joseph; KAU; Gopakumar, S
    Natural gum based bionanocomposite film using babul gum obtained from Vachellia nilotica .L and cellulose nanofibrils (CNF) extracted from bamboo culms via steam explosion cum acid treatment was developed for biomedical and packaging applications. Alkali treatment (using NaOH) followed by bleaching (using sodium hypochlorite) of chopped bamboo culms resulted in removal of impurities like pectin, lignin, hemicellulose and other organic compounds. Steam coupled acid treatment of the bleached cellulose pulp resulted in the depolymerization and defibrillation of the fibres to produce cellulose nanofibrils. The structural, morphological, chemical, and thermal properties of CNF were analysed using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD) and Thermogravimetric Analysis (TGA). TEM and SEM images showed that the CNF was composed of network like structure of long fibrils of nanocellulose having the size of few micrometres in length and 50-60 nm in width. The CNF had a crystallinity of 54.46% which was greater than that of the raw bamboo fibre (41%). The chemical composition of the raw fibre and the CNF was analysed by FT-IR micrographs. TGA showed that the CNF was thermally more stable than the raw fibre and the results of peak temperature of 10 and 20% weight loss of raw fibre and CNF substantiated the same. The effect of CNF content (1, 3, 5, and 10 wt% based on gum) on the thermal, mechanical, water solubility, contact angle, and moisture content of nanocomposites was studied. Properties of babul gum film such as mechanical properties were improved significantly (p<0.05) by combining with CNF. The TGA analysis revealed that the composites had more thermal stability than the pristine gum film. The tensile and elastic modulus of composites increased significantly (p<0.05) when the concentration of the CNF increased in the gum matrix, while the elastic property decreased with the addition of CNF. The contact angle was found to be increasing with increasing the concentration of CNF added to the gum 64 matrix resulting in less hydrophilic composite with high CNF content. The moisture content tested for the composite films showed no significant difference with the addition of CNF. Water solubility tested showed around 90-95% of the film was dissolved completely in water. The CNF obtained from bamboo fibre can be used as reinforcing agent for the preparation of bio-nanocomposites and they can have a high potential for the development of completely biodegradable edible films which can be used for biomedical applications and packaging.
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    ThesisItemOpen Access
    Impact of invasive alien Plants on understorey vegetation in Tholpetty range of Wayanad Wildlife Sanctuary
    (Department of Natural Resource Management, College of Forestry, Vellanikkara, 2019) Harilal, K; KAU; Gopakumar, S
    A study titled “Impact of invasive alien plants (IAP) on understorey vegetation in Tholpetty Range of Wayanad Wildlife Sanctuary” was undertaken to understand the distribution characteristics of selected invasive alien plant species (IAPS) viz., Lantana camara L., Senna spectabilis (DC.) H.S. Irwin and R.C. Barneby and Chromolaena odorata (L.) R.M. King & H. Robin in the three vegetation types (Plantation, NF, and Vayal) of WS I part of the WWLS. The additional objective was to assess the impact of these IAPS on the native plant communities in these vegetation types. In the WS I area, L. camara invasion was rampant, except in the southern regions. Higher invasion was seen in the Kaimaram and Thirulkunnu forest sections. C. odorata invaded all the four sections viz. Kaimaram, Dasanghatta, Thirulkunnu and Bavali. S. spectabilis invasion was heavy in the Kaimaram section near the boundary of Thirunelli RF, and in the boundaries between Nagarhole TR and Kaimaram section. In all the three vegetation types, the density of Chromolaena was high, while it was lowest for Senna. The density of Chromolaena in NF, Plantation and Vayal was respectively 3734.11 ± 5.65, 8457.64 ± 27.52 and 7761.17 ± 9.74 stems/ha. The density of Lantana in NF, plantation and Vayal was respectively 1061.17 ± 2.75,334.11 ± 1.02and 215.29 ± 0.50stems/ha. The density of Senna in NF, plantation and Vayal was 414.11 ± 1.55, 589 ± 2.67 and 34.11 ± 0.21stems/ha respectively. In the Vayals, Senna invasion, though minimal, could be noticed. Chromolaena had the highest percentage cover in both plantation (24.58 ± 3.06) and Vayal (46.19 ± 4.03). In NF, Lantana (19.46± 3.43) had the highest percentage cover. In all the three vegetation types, Chromolaena had the highest frequency and abundance. Out of the total 140 plant species identified from the WS I region, number of species recorded in each weed category types like L, C, S, LC, CS, LS, LCS and Control were 67, 96, 20, 64, 9, 7, 14 and 113 respectively. Vis-a-vis the impacts of IAPS in NF, highest MSR (Mean Species Richness) was seen in Control (weed-free area), followed by L (Lantana invaded) and C (Chromolaena invaded) regions. The lowest MSR was in LCS (Lantana, Chromolaena, and Senna invaded) and LS (Lantana and Senna invaded) regions. In plantation, highest MSR was seen in Control (weed-free area) and the lowest in L (Lantana invaded) area. In Vayal too, highest MSR was observed in control, followed by C (Chromolaena invaded) and lowest in LC (Lantana and Chromolaena invaded) areas. All three IAPS negatively influenced the native species richness, although no specific declining trend in species richness could be observed. Among the three IAPS, C. odorata had the biggest impact on the species richness of native species in both NF and Vayal. In the plantations, L.camara had the biggest impact on species richness. Canopy openness and percentage cover of IAPS were found to be positively correlated. In NF and Vayal, Lantana showed highest correlation with canopy openness, while in plantation, Chromolaena showed highest correlation with canopy openness. In plots where Senna and Lantana occurred together, plant species richness decreased from 67 to 7. Similarly, when Senna and Chromolaena came together, species richness dropped from 96 to 9. This probably indicates a dominating interference of Senna on the recruitment of native species which needs research attention. Left unmanaged, Senna will soon become a major “biological pollutant” of Wayanad WLS.