Mochamad Chalid

Study of Synthesis of Novel ɤ-Valerolactone-Based Polyurethanes

The ring opening of -valerolactone (GVL) with amine compounds was reported as a promising molecular engineering tool to synthesize precursors for new bio-based polymers such as polyurethanes (PUs). Experimental work on the synthesis of polymers based on GVL/1,2-ethanolamine and GVL/1,2-diaminoethane adducts, and di-isocyanates (1,4-phenylene-di-isocyanate (PDI) 2,4-toluene-di-isocyanate (TDI) and hexamethylene-di-isocyanate (HDI)) is described. The polymers were characterized by FTIR, 1H-NMR, 13C-NMR, elemental analysis and GPC. The best polymerization results were obtained using TEA as the catalyst, DMA as the solvent and a temperature of 140°C for the reaction of the GVL/1,2-aminoethanol adduct with TDI. A polymer with a molecular weight (Mw) of 156 KDalton was produced in 97% yield.

Preparation of micro-fibrillated cellulose from sorghum fibre through alkalization and acetylation treatments

Recently, the pollution due to non-degradable materials including plastics, has led to needs on the development of environmental-friendly material. Owing to its biodegradability nature, sorghum fibres are interesting to be modified with petro-polymer as a composite. These materials are also expected to reduce the impact of environmental pollution. Surface modification of sorghum through chemical treatment was aimed to enhanced crystalline part of micro-fibrillated cellulose, thus increased compatibility to petro-polymer, as mean to improve composite properties. The experiments were conducted by alkalization process (10% NaOH) followed by acetylation with acetic acid glacial and acetic anhydride (CH3CO2)2 with additions of 1 and 2 drops of 25% H2SO4. Fourier transform infra-red (FTIR) spectroscopy, field-emission scanning electron microscope (FE-SEM) and x-ray diffraction (XRD) were used to characterize the treated and untreated fibres. The results of investigation showed that the chemical treatments have effectively produced MFC with the smallest fibre size around 5.5 – 6.5 microns and reduced lignin and hemicellulose where the highest crystalline part up to 80.64% was obtained through acetate acid treatment of 17.4 M, followed acetic anhydride with 1 drop of H2SO4 addition. Based on the current results, it is promising that the synthesized composites can be improved for their compatibilities.

Structure - Mechanical and Thermal Properties Relationship of Novel gamma-Valerolactone-Based Polyurethanes

Polymerization of biomass-based diol precursors such as N,N’-1,2-ethanediylbis-(4-hydroxy-pentanamide) and 4-hydroxy-N-(2-hydroxyethyl)-pentanamide with aliphatic (hexamethylene diisocyanate, HDI) and aromatic di-isocyanates (1,4-phenylene-di-isocyanate, PDI and 2,4-toluene-di-isocyanate,TDI) resulted in some novel polyurethanes. The diol precursors were obtained from the ring opening of γ-valerolactone, GVL, with amine compounds reported as a promising molecular engineering tool to synthesize precursors for new biobased polymers. An interesting investigation about the relationship between structures of the diols and properties such as thermal and mechanical behavior of the obtained polyurethanes was reported in this article. Observation of thermal properties of the polymers showed that the polyurethanes are amorphous and thermally stable until 250°C, with a maximum glass transition temperature of 128°C. The polymer with the highest molecular weight, i.e., 147 kD for the polyurethane made from TDI and 4-hydroxy-N-(2-hydroxyethyl)-pentanamide, showed a high elastic modulus (2,210 MPa), which brings this bio-based system within the window of commercial polyurethane applications. GRAPHICAL ABSTRACT

Study of crystallization kinetics of peek thermoplastics using Nakamura equation

We have simulated the time evolution of relative crystallization of PEEK at various cooling rates (10, 15, 20 °C/min) and made comparison with the experiments. The simulation was conducted using Nakamura model which is a modified Avrami model. The model is a 1 cm radius of circle with the cooling plate which was placed in the upper part of the circle. The cooling plate temperature was varied in order to obtain particular cooling rates. The measurement point is located near upper boundary in order to minimize the heat transfer effect. The general trend of time evolution of crystallization was well captured although some discrepancies occured. These discrepancies may be attributed to the heat transfer effect and secondary crystallization.We have simulated the time evolution of relative crystallization of PEEK at various cooling rates (10, 15, 20 °C/min) and made comparison with the experiments. The simulation was conducted using Nakamura model which is a modified Avrami model. The model is a 1 cm radius of circle with the cooling plate which was placed in the upper part of the circle. The cooling plate temperature was varied in order to obtain particular cooling rates. The measurement point is located near upper boundary in order to minimize the heat transfer effect. The general trend of time evolution of crystallization was well captured although some discrepancies occured. These discrepancies may be attributed to the heat transfer effect and secondary crystallization.

Effect of Arenga Pinnata “Ijuk” Fiber as Nucleating Agent on Crystallization Kinetics of Impact Polypropylene Copolymer

Impact Polypropylene Copolymer (IPC) is one of the PP type which is widely used. IPC was made with addition of ethylene in PP which decreases PP crystallinity. Many efforts have been made to improve the properties of PP crystallinity by addition of nucleating agents. In this study, we use Arenga Pinnata “Ijuk” fiber as PP nucleating agent. In order to determine the effect of “Ijuk” fiber as nucleating agents in kinetics aspect, we used DSC measurement based on Avrami equation. The results showed that the addition of ijuk decreases crystallizationhalf timeand dimension of crystal growth which indicate the effects of “Ijuk” fiber as a nucleating agent.

Screening of proteins based on macro-algae from West Java coast in Indonesian marine as a potential anti-aging agent

Algae has been known as one of the potential marine bio-resources that have been used in many fields such as bio-energy, food, pharmaceutical and medical applications. Study of macro-algae or seaweed for medicine application, in particular, highlights to empower their ingredients as a promising antioxidant like anti-aging agent due to their diversity in biological activity. The tropical climate of Indonesia with the highest marine biodiversity puts this country an auspicious source of numerous alga species as a novel antioxidant source. A Sample of 29 species of macroalgae has been collected from Coast of Pari Island as a part of Seribu Islands, Indonesia. Screening and extracting of aqueous tropical marine alga protein as a potential source for an antioxidant agent has been done by using 2,2-diphenyl-1-picrylhydrazyl scavenging method, and protein contents have been determined by Lowry method. Sample number 26 of the phylum Rhodophyta have 9.00±0.03 % protein content, which is potential for nutritional f...

Study of Nano-Fe3O4 Addition on Magnetic and Mechanical Properties of HMDI-Based Polyurethane

Polyurethane has a wide range of chemical structures available led to the design of materials that easily can meet requirements to shape memory polyurethane (SMPU) due to its ability to retain its shape after deformation through giving a certain disturbance like magnetic field. Based on the previous study, polyurethanes synthesized by reacting 4,4’-methylenebis (cyclohexyl isocyanate) to poly(ethylene glycol) Mw: 6000 as polyurethane chain with 1,1,1-trimethylol propane as chain extender, is a potential candidate for shape memory polyurethane (SMPU). Furthermore this study was performed by adding Fe3O4 nanoparticles as a filler to provide magnetic behavior. In this study, The magnetic and mechanical properties of the SMPU after adding Fe3O4 nanoparticles were evaluated by observing compatibility between the filler and matrix, morphology, ability in retaining shape, and mechanical properties through measuring FTIR, FESEM, Vibrating Magnetometer and UTM, respectively. This study reported a good compatibility between Fe3O4 and the polyurethane, and lack agglomeration of Fe3O4 nanoparticles indicated FTIR and FESEM-EDAX, the fastest ability on retaining its shape obtained from materials with lowest Fe3O4 (3 wt%). Meanwhile the best mechanical and magnetic was resulted from adding 11 wt% of Fe3O4

Effect of urea deproteinization on catalytic hydrogenation of natural rubber latex

Natural rubber is unsaturated biopolymer which has low resistance to heat, oxygen, and ozone. Chemical modification of natural rubber by catalytic hydrogenation can improve its oxidative property. In this study, the catalytic hydrogenation of natural rubber was investigated in latex phase after reduction of protein content with urea. Hydrogenation of deproteinized natural rubber latex was performed by using diimide which generated insitu from hydrazine hydrate/hydrogen peroxide and catalyst (boric acid, cupric sulfate and cupric acetate) at 70°C for 5 h. The hydrogenation system was stabilized with sodium dodecyl sulphate. The hydrogenation of deproteinized natural rubber (HDPNR) was confirmed by FTIR analysis. The result indicated that cupric sulphate was extremely active catalyst which was showed by the elimination of C=C transmittance bands at 1660 cm-1 on HDPNR spectra and highest degree of hydrogenation. Furthermore, urea deproteinization increased possibility of side reactions during catalytic hydrogenation as seen on the reduction of gel content compared to undeproteinized natural rubber.