SINTESIS DAN KARAKTERISASI HIDROGEL CRF (CONTROLLED RELEASE FERTILIZER) BERBASIS KOMPOSIT PVA-ALGA MERAH-CARBON NANOTUBE

Telah dilakukan penelitian tentang sintesis dan karakterisasi hidrogel CRF (controlled release fertilizer) berbasis komposit PVA-alga merah-carbon nanotube. Penelitian ini bertujuan untuk mengetahui komposisi optimum filler carbon nanotube (CNT) pada sintesis hidrogel komposit, mengetahui karakteristik hidrogel komposit, serta mengetahui kinerja hidrogel komposit sebagai material CRF. Penelitian yang dilakukan terdiri dari tiga tahap: (1) tahap optimasi komposisi CNT dalam hidrogel komposit, (2) tahap sintesis hidrogel komposit, dan (3) tahap karakterisasi hidrogel komposit. Komposisi optimum filler CNT dalam komposit PVA-alga merah adalah 5 mL CNT (dispersi) pada rasio komposisi PVA:Alga merah:CNT = 10:10:5, dimana kemampuan swelling (%SR) dan waktu retensi air optimum hidrogel komposit mencapai 840% dan 21 hari, secara berturut-turut. Hasil karakterisasi menunjukkan hidrogel komposit merupakan material berpori, serta penyisipan CNT dan nutrien dapat meningkatkan kristalinitas dari hidrogel komposit dimana interaksi prekursor hidrogel komposit (PVA-Alga merah-CNT-nutrien) berlangsung dengan melibatkan gugus fungsi C-O, C-N, C=O, C-H sp3 dan O-H, yang dikonfimasi dengan perubahan intensitas dan pergeseran puncak untuk serapan gugus fungsi tersebut. Penyisipan nutrien dapat meningkatkan kinerja dari hidrogel komposit yang dindikasikan oleh %SR dan waktu retensi mencapai 1419% dan 21 hari, secara berturut-turut. Selain itu, hidrogel komposit dapat digunakan sebagai material hidrogel CRF dengan kategori slow released dan hidrogel komposit berpotensi biodegradable. A research on the synthesis and characterization of CRF hydrogel composite (controlled release fertilizer) based on PVA-Red Algae-Carbon Nanotubes has been done. This study aims to determine the optimum composition of the carbon nanotube (CNT) filler on the synthesis of hydrogel composite, to determine the characteristics of hydrogel composite, and to determine the performances of hydrogel composite as a CRF material. The study was conducted in three stages: (1) the optimization of CNT composition in hydrogel composite, (2) synthesis of hydrogel composite, and (3) the characterization of hydrogel composites. The optimum composition of CNT filler in hydrogel composite is 5 mL of CNT (dispersion) with the composition ratio of PVA: red algae: CNT = 10: 10: 5, where the ability of swelling (% SR) and optimum water retention time of hydrogel composite reached 840% and 21 days, respectively. The results showed that hydrogel composite is a porous material, and the insertion of CNT and nutrients could improved the crystallinity of the hydrogel composite, wherein the hydrogel precursor interaction (PVA-red algae-CNT-nutrient) took place with the involvement of functional groups C-O, C-N, C = O, C-H sp3 and O-H, which is confirmed by the changes in absorption peak’s intensity and the shifts of the functional group. Insertion of nutrients could improve the performances of hydrogel composite which is indicated by %SR and the retention time of 1419% and 21 days, respectively. In addition, the hydrogel composite can be used as CRF material with slow released category and the hydrogel composite is potentially biodegradabl

EFFECTS OF STARCH-GLYCEROL CONCENTRATION RATIO ON MECHANICAL AND THERMAL PROPERTIES OF CASSAVA STARCH-BASED BIOPLASTICS

This study aimed to investigate the effects of different starch-glycerol concentration ratio on mechanical and thermal properties of cassava starch bioplastics. Bioplastics were prepared by mixing starch with glycerol at different starch-glycerol w/w ratio (2.5:1, 2.75:1, 3:1 and 3.5:1). Mechanical properties was evaluated by measuring tensile strength and elongation at break where thermal properties was assessed by thermogravimetric analysis to determine the glass transition temperature (Tg), melting temperature (Tm) and melting enthalpy (ΔHm) of bioplastics. Microstructure and chemical interactions in bioplastics were evaluated by SEM and FTIR. The surface hydrophobicity was determined by measuring the water contact angle. The increase of starch-glycerol concentration in bioplastics formed rough surface where the interaction of glycerol and starch molecules mainly occurred through hydrogen bonds. It also formed stronger and more rigid structure with the increase in tensile strength from 1.90 MPa to 2.47 MPa and the decrease in elongation at break from 8.55% to 5.92%. Furthermore, the increase of starch-glycerol concentration increased Tg from 37.5 ºC to 38.6 ºC, Tm from 96.3 ºC to 120.7 ºC and ΔHm from 100.4 J/g to 155 J/g. Moreover, surface contact angle of bioplastics was increased from 40.6º to 60.2º with the increase of starch-glycerol concentration ratio

Preparation of Eumelanin-Encapsulated Stereocomplex Polylactide Nano/Microparticles for Degradable Biocompatible UV-Shielding Products

The role of eumelanin as a natural pigment in protecting human skin from ultraviolet (UV) light has drawn vast interest in the research and industrial community. Encapsulation of the compound by various shell materials has been extensively studied to optimize and prolong its shielding efficiency from UV penetration through the skin. Polylactide (PLA)-based copolymers have been widely used in the encapsulation of various active compounds due to their biocompatibility and biodegradability that facilitate sustained release of the active compounds. In this work, stereocomplex PLA (sc-PLA) derived from mixtures of poly(D-lactide-caprolactone-D-lactide), P(DLA-b-CL-b-DLA), a triblock copolymer with linear poly(L-lactide), and PLLA are employed to encapsulate eumelanin by an oil-in-water emulsion (O/W) technique. The effect of eumelanin distribution in PLA’s enantiomers and ultrasonication on the physicochemical properties, encapsulation efficiency, and release behavior of the nano/microparticles were evaluated. The potential application of the resulting particles for sunscreen products was assessed in terms of UV absorbance and in vitro sun protection factor (SPF). The nano/microparticles show a hollow spherical structure, whose size can be controlled by ultrasonication. The distribution of eumelanin and the ultrasonication process play a key role in the growth of sc-PLA and the crystalline structure of the particles. The highest encapsulation efficiency of 46.6% was achieved for sc-PLA2U particles. The high content of eumelanin and the hollow structure with a large surface area lead to improvement in the UV absorbance and sunscreen performance of the particles, as revealed by the increase in the SPF value from 9.7 to 16.5. The materials show high potential for various applications, especially in cosmetic and pharmaceutical fields, as UV-shielding products