Displaying publications 81 - 100 of 160 in total

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  1. Fulltext Hydroxypropyl Cellulose Based Non-Volatile Gel Polymer Electrolytes for Dye-Sensitized Solar Cell Applications using 1-methyl-3-propylimidazolium iodide ionic liquid
    Khanmirzaei MH, Ramesh S, Ramesh K
    Sci Rep, 2015;5:18056.
    PMID: 26659087 DOI: 10.1038/srep18056
    Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10(-3) S cm(-1) is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm(-2), 610 mV and 69.1%, respectively.
    Matched MeSH terms: Calorimetry, Differential Scanning
  2. Immobilization of β-glucosidase from Aspergillus niger on κ-carrageenan hybrid matrix and its application on the production of reducing sugar from macroalgae cellulosic residue
    Tan IS, Lee KT
    Bioresour Technol, 2015 May;184:386-94.
    PMID: 25465785 DOI: 10.1016/j.biortech.2014.10.146
    A novel concept for the synthesis of a stable polymer hybrid matrix bead was developed in this study. The beads were further applied for enzyme immobilization to produce stable and active biocatalysts with low enzyme leakage, and high immobilization efficiency, enzyme activity, and recyclability. The immobilization conditions, including PEI concentration, activation time and pH of the PEI solution were investigated and optimized. All formulated beads were characterized for its functionalized groups, composition, surface morphology and thermal stability. Compared with the free β-glucosidase, the immobilized β-glucosidase on the hybrid matrix bead was able to tolerate broader range of pH values and higher reaction temperature up to 60 °C. The immobilized β-glucosidase was then used to hydrolyse pretreated macroalgae cellulosic residue (MCR) for the production of reducing sugar and a hydrolysis yield of 73.4% was obtained. After repeated twelve runs, immobilized β-glucosidase retained about 75% of its initial activity.
    Matched MeSH terms: Calorimetry, Differential Scanning
  3. In Vitro Investigation of Influences of Chitosan Nanoparticles on Fluorescein Permeation into Alveolar Macrophages
    Chachuli SH, Nawaz A, Shah K, Naharudin I, Wong TW
    Pharm Res, 2016 06;33(6):1497-508.
    PMID: 26951565 DOI: 10.1007/s11095-016-1893-5
    PURPOSE: Pulmonary infection namely tuberculosis is characterized by alveolar macrophages harboring a large microbe population. The chitosan nanoparticles exhibit fast extracellular drug release in aqueous biological milieu. This study investigated the matrix effects of chitosan nanoparticles on extracellular drug diffusion into macrophages.

    METHODS: Oligo, low, medium and high molecular weight chitosan nanoparticles were prepared by nanospray drying technique. These nanoparticles were incubated with alveolar macrophages in vitro and had model drug sodium fluorescein added into the same cell culture. The diffusion characteristics of sodium fluorescein and nanoparticle behavior were investigated using fluorescence microscopy, scanning electron microscopy, differential scanning calorimetry and Fourier transform infrared spectroscopy techniques.

    RESULTS: The oligochitosan nanoparticles enabled macrophage membrane fluidization with the extent of sodium fluorescein entry into macrophages being directly governed by the nanoparticle loading. Using nanoparticles made of higher molecular weight chitosan, sodium fluorescein permeation into macrophages was delayed due to viscous chitosan diffusion barrier at membrane boundary.

    CONCLUSION: Macrophage-chitosan nanoparticle interaction at membrane interface dictates drug migration into cellular domains.

    Matched MeSH terms: Calorimetry, Differential Scanning
  4. Fulltext Influence of Ispaghula and Zein Coating on Ibuprofen-Loaded Alginate Beads Prepared by Vibration Technology: Physicochemical Characterization and Release Studies
    Lyn Heng JJ, Teng JH, Saravanan M, Pushpamalar J
    Sci Pharm, 2018 Jun 05;86(2).
    PMID: 29874858 DOI: 10.3390/scipharm86020024
    The purpose behind the work was to fabricate alginate beads with better drug loading and extended drug release. Ispaghula was used to enhance the drug loading while zein was employed to extend the drug release. Ibuprofen was employed as a model drug in this study. Ibuprofen-loaded alginate beads with and without ispaghula were prepared using vibration technology and coated with zein. The beads prepared with alginate alone were shown to have loading and entrapment efficiencies of 35% and 70% w/w, respectively. Addition of ispaghula in alginate showed a significant increase (p < 0.05) in the drug loading (42% w/w) and entrapment efficiency (84% w/w). Fourier-transform infrared spectroscopy confirmed the presence of ispaghula and zein coating in the alginate beads as well as the ibuprofen loading. Scanning electron microscopy revealed better spherical geometry in the beads with ispaghula. The surface morphology of the uncoated beads was rough due to crystalline and surface drug. The zein coating has produced a smoother surface and particle adhesion. Differential scanning calorimetry has shown a reduction in drug crystallinity. Alginate beads extended the drug release for 4 h and the presence of zein extended the release for 6 h.
    Matched MeSH terms: Calorimetry, Differential Scanning
  5. Fulltext Influence of electron irradiation factor on haruan traditional extract (HTE) for oral drug delivery
    Ibrahim, I., Abdul Manan, M.J., Kamaruddin, H.
    Jurnal Sains Nuklear Malaysia, 2014;26(1):1-8.
    MyJurnal
    Haruan or Channa striatus is source of protein that is widely consumed in the region and its extract
    is well known for having medical values. It is of great advantage if this product could be taken
    orally rather than by injection because the oral route of drug delivery is still preferred by the vast
    majority of patients. However protein and peptides can be denatured or degraded by the acidic pH
    of the stomach and the presence of endogenous enzymes. In order to protect or prevent digestion
    and degradation of the protein in the stomach and to ensure the protein reaches the gastro
    intestinal (GI) tract, Carboxymethyl Starch (CMS) nanogel system was developed using electron
    irradiation method. However stability of HTE during the irradiation process needed to be studied
    before being developed further. In this study, the HTE was irradiated using electron beams. Its
    stability was analysed in terms of physical and chemical changes by looking at colour difference,
    melting point by using Differential Scanning Calorimetry (DSC) and molecular bonds by using
    Fourier Transform Infrared (FTIR) respectively. The results of this study were that no apparent
    colour difference was observed with HTE before and after irradiation. These observations were
    supported by the FTIR and DSC results that showed that there were no changes in molecular bonds
    and melting point, compared between no irradiation and irradiation HTE during electron
    irradiation up to 10 kGy. Statistically the test showed no significant difference at p < 0.005 between
    melting temperatures.
    Matched MeSH terms: Calorimetry, Differential Scanning
  6. Investigation of physical properties and stability of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems prepared by quench cooling, coprecipitation and ball milling
    Lim AW, Löbmann K, Grohganz H, Rades T, Chieng N
    J Pharm Pharmacol, 2016 Jan;68(1):36-45.
    PMID: 26663364 DOI: 10.1111/jphp.12494
    The objective was to characterize the structural behaviour of indomethacin-cimetidine and naproxen-cimetidine co-amorphous systems (1 : 1 molar ratio) prepared by quench cooling, co-evaporation and ball milling.
    Matched MeSH terms: Calorimetry, Differential Scanning
  7. Keratin based bioplastic film from chicken feathers and its characterization
    Ramakrishnan N, Sharma S, Gupta A, Alashwal BY
    Int J Biol Macromol, 2018 May;111:352-358.
    PMID: 29320725 DOI: 10.1016/j.ijbiomac.2018.01.037
    Plastics have been one of the highly valued materials and it plays an significant role in human's life such as in food packaging and biomedical applications. Bioplastic materials can gradually work as a substitute for various materials based on fossil oil. The issue like sustainability and environmental challenges which occur due to manufacturing and disposal of synthetic plastics can be conquering by bio-based plastics. Feathers are among the most inexpensive abundant, and renewable protein sources. Feathers disposal to the landfills leads to environmental pollutions and it results into wastage of 90% of protein raw material. Keratin is non-burning hydrophilic, and biodegradable due to which it can be applicable in various ways via chemical processing. Main objective of this research is to synthesis bioplastic using keratin from chicken feathers. Extracted keratin solution mixed with different concentration of glycerol (2 to 10%) to produce plastic films. The mixture was stirred under constant magnetic stirring at 60 °C for 5 h. The mixtures are then poured into aluminum weighing boat and dried in an oven at 60 °C for 24 h. The mechanical properties of the samples were tested and the physic-chemical properties of the bioplastic were studied. According to the results, Scanning Electron Microscopy test showed good compatible morphologies without holes, cavity and edge. The difference in chemical composition was analyzed using Fourier transform infrared spectroscopy (FTIR). The samples were also characterized by thermo gravimetric analysis (TGA), differential scanning calorimetry (DSC), X-Ray diffraction (XRD) to check the thermal and crystallinity properties. Other than that, bioplastic made up from keratin with 2% of glycerol has the best mechanical and thermal properties. According to biodegradability test, all bioplastic produced are proven biodegradable. Therefore, the results showed possible application of the film as an alternative to fossil oil based materials which are harmful to the environment.
    Matched MeSH terms: Calorimetry, Differential Scanning
  8. Fulltext Kinetics and Optimization of Lipophilic Kojic Acid Derivative Synthesis in Polar Aprotic Solvent Using Lipozyme RMIM and Its Rheological Study
    Ishak N, Lajis AFB, Mohamad R, Ariff AB, Mohamed MS, Halim M, et al.
    Molecules, 2018 Feb 24;23(2).
    PMID: 29495254 DOI: 10.3390/molecules23020501
    The synthesis of kojic acid derivative (KAD) from kojic and palmitic acid (C16:0) in the presence of immobilized lipase from Rhizomucor miehei (commercially known as Lipozyme RMIM), was studied using a shake flask system. Kojic acid is a polyfunctional heterocycles that acts as a source of nucleophile in this reaction allowing the formation of a lipophilic KAD. In this study, the source of biocatalyst, Lipozyme RMIM, was derived from the lipase of Rhizomucor miehei immobilized on weak anion exchange macro-porous Duolite ES 562 by the adsorption technique. The effects of solvents, enzyme loading, reaction temperature, and substrate molar ratio on the reaction rate were investigated. In one-factor-at-a-time (OFAT) experiments, a high reaction rate (30.6 × 10-3 M·min-1) of KAD synthesis was recorded using acetone, enzyme loading of 1.25% (w/v), reaction time of 12 h, temperature of 50 °C and substrate molar ratio of 5:1. Thereafter, a yield of KAD synthesis was optimized via the response surface methodology (RSM) whereby the optimized molar ratio (fatty acid: kojic acid), enzyme loading, reaction temperature and reaction time were 6.74, 1.97% (w/v), 45.9 °C, and 20 h respectively, giving a high yield of KAD (64.47%). This condition was reevaluated in a 0.5 L stirred tank reactor (STR) where the agitation effects of two impellers; Rushton turbine (RT) and pitch-blade turbine (PBT), were investigated. In the STR, a very high yield of KAD synthesis (84.12%) was achieved using RT at 250 rpm, which was higher than the shake flask, thus indicating better mixing quality in STR. In a rheological study, a pseudoplastic behavior of KAD mixture was proposed for potential application in lotion formulation.
    Matched MeSH terms: Calorimetry, Differential Scanning
  9. Fulltext Lightweight and Durable PVDF-SSPF Composites for Photovoltaics Backsheet Applications: Thermal, Optical and Technical Properties
    Alaaeddin MH, Sapuan SM, Zuhri MYM, Zainudin ES, M Al-Oqla F
    Materials (Basel), 2019 Jun 29;12(13).
    PMID: 31261926 DOI: 10.3390/ma12132104
    Photovoltaic module backsheets are characterized according to their thermal, optical, mechanical, and technical properties. This work introduces new fabricated backsheets for PV modules using polyvinylidene fluoride (PVDF) reinforced with short sugar palm fiber (SSPF) composites. The preparation of composites undergoes multiple phases of fabrication. Thermal, optical, and technical investigations of their properties were conducted. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, in-situ scanning probe microscopy (SPM), dynamic mechanical analysis (DMA), thermal mechanical analysis (TMA), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and prolonged technical testing were accomplished to expansively understand the complex behavior of composites under various conditions. The optical properties of PV backsheets are critical components in determining the reflectance, absorbance, and transmittance of light. The PVDF-SSPF composites exhibited exceptional compatibility and thermal stability, further revealing a homogenous composite structure with enhanced interfacial bonding between the short fiber and polymer matrix.
    Matched MeSH terms: Calorimetry, Differential Scanning
  10. Linear low density polyethylene/poly (vinyl alcohol)/kenaf composites: effect of natural weathering on functional group, weight loss characteristics, tensile, morphological and thermal properties
    Pang AL, Azhar Abu Bakar, Hanafi Ismail
    Sains Malaysiana, 2018;47:571-580.
    The development of natural fiber polymer composites is increasing worldwide and in some applications, these composites
    are used at outdoor rendering them exposed to ultra-violet (UV) radiation. The paper investigates the degradation behavior
    of linear low density polyethylene/poly (vinyl alcohol)/kenaf (LLDPE/PVOH/KNF) composites after exposure to different
    natural weathering durations. The composites with KNF loadings of 10, 20 and 40 parts per hundred resin (phr) were
    exposed to natural weathering for 3 months and 6 months, respectively. The weathered composites were characterized by
    Fourier transform infrared (FTIR) spectroscopy, universal testing machine, field emission scanning electron microscopy
    (FESEM) and differential scanning calorimetry (DSC). The FTIR analysis showed an obvious carbonyl peak in composites
    after weathering as an evidence of oxidation. The weight loss percentage of composites increased with respect to exposure
    duration due to higher absorption of UV irradiation. The tensile properties of weathered composites were lower than
    that of control composites and these properties also decreased with increasing exposure duration. FESEM micrographs
    illustrated that composites with longer exposure duration suffered more surface damaged. The crystallinity percentage
    was found to increase with increasing exposure duration.
    Matched MeSH terms: Calorimetry, Differential Scanning
  11. Lipase catalyzed ultrasonic synthesis of poly-4-hydroxybutyrate-co-6-hydroxyhexanoate
    Gumel AM, Annuar MS, Chisti Y
    Ultrason Sonochem, 2013 May;20(3):937-47.
    PMID: 23231942 DOI: 10.1016/j.ultsonch.2012.09.015
    Four different lipases were compared for ultrasound-mediated synthesis of the biodegradable copolymer poly-4-hydroxybutyrate-co-6-hydroxyhexanoate. The copolymerization was carried out in chloroform. Of the enzymes tested, Novozym 435 exhibited the highest copolymerization rate, in fact the reaction rate was observed to increase with about 26-fold from 30 to 50°C (7.9×10(-3)Ms(-1)), sonic power intensity of 2.6×10(3)Wm(-2) and dissipated energy of 130.4Jml(-1). Copolymerization rates with the Candida antarctica lipase A, Candida rugosa lipase, and Lecitase Ultra™ were lower at 2.4×10(-4), 1.3×10(-4) and 3.5×10(-4)Ms(-1), respectively. The catalytic efficiency depended on the enzyme. The efficiency ranged from 4.15×10(-3)s(-1)M(-1) for Novozym 435-1.48×10(-3)s(-1)M(-1) for C. rugosa lipase. Depending on the enzyme and sonication intensity, the monomer conversion ranged from 8.2% to 48.5%. The sonication power, time and temperature were found to affect the rate of copolymerization. Increasing sonication power intensity from 1.9×10(3) to 4.5×10(3)Wm(-2) resulted in an increased in acoustic pressure (P(a)) from 3.7×10(8) to 5.7×10(8)Nm(-2) almost 2.4-3.7 times greater than the acoustic pressure (1.5×10(8)Nm(-2)) that is required to cause cavitation in water. A corresponding acoustic particle acceleration (a) of 9.6×10(3)-1.5×10(4)ms(-2) was calculated i.e. approximately 984-1500 times greater than under the action of gravity.
    Matched MeSH terms: Calorimetry, Differential Scanning
  12. Fulltext Lipid effects on expulsion rate of amphotericin B from solid lipid nanoparticles
    Tan SW, Billa N
    AAPS PharmSciTech, 2014 Apr;15(2):287-95.
    PMID: 24318197 DOI: 10.1208/s12249-013-0056-9
    We aimed to investigate the effects that natural lipids, theobroma oil (TO) and beeswax (BW), might have on the physical properties of formulated nanoparticles and also the degree of expulsion of encapsulated amphotericin B (AmB) from the nanoparticles during storage. Lecithin and sodium cholate were used as emulsifiers whilst oleic acid (OA) was used to study the influence of the state of orderliness/disorderliness within the matrices of the nanoparticles on the degree of AmB expulsion during storage. BW was found to effect larger z-average diameter compared with TO. Lecithin was found to augment the stability of the nanoparticles imparted by BW and TO during storage. An encapsulation efficiency (%EE) of 59% was recorded when TO was the sole lipid as against 42% from BW. In combination however, the %EE dropped to 39%. When used as sole lipid, TO or BW formed nanoparticles with comparatively higher enthalpies, 21.1 and 23.3 J/g respectively, which subsequently caused significantly higher degree of AmB expulsion, 81 and 83% respectively, whilst only 11.8% was expelled from a binary TO/BW mixture. A tertiary TO/BW/OA mixture registered the lowest enthalpy at 8.07 J/g and expelled 12.6% of AmB but encapsulated only 22% of AmB. In conclusion, nanoparticles made from equal concentrations of TO and BW produced the most desirable properties and worthy of further investigations.
    Matched MeSH terms: Calorimetry, Differential Scanning
  13. Fulltext Liquid-Crystal and Fire-Retardant Properties of New Hexasubstituted Cyclotriphosphazene Compounds with Two Schiff Base Linking Units
    Jamain Z, Khairuddean M, Guan-Seng T
    Molecules, 2020 May 01;25(9).
    PMID: 32370000 DOI: 10.3390/molecules25092122
    A series of new hexasubstituted cyclotriphosphazene compounds (4a-j) consisting of two Schiff base linking units and different terminal substituents was successfully synthesized and characterized. The structures of these compounds were confirmed using Fourier Transform Infra-Red (FTIR), Nuclear Magnetic Resonance (NMR), and CHN elemental analysis. Polarized optical microscopy (POM) was used to determine their liquid-crystal behavior, which was then further confirmed using differential scanning calorimetry (DSC). Compounds 4a-i with heptyl, nonyl, decyl, dodecyl, tetradecyl, hydroxy, 4-carboxyphenyl, chloro, and nitro terminal ends, respectively, showed the liquid-crystal properties, whereas compound 4j with the amino group was found to be non-mesogenic. The attachment of an electron-donating group in 4j eventually give a non-mesogenic product. The study of the fire-retardant properties of these compounds was done using the limiting oxygen index (LOI). In this study, polyester resin (PE) was used as a matrix for moulding, and the LOI value of pure PE was 22.53%. The LOI value increased to 24.71% when PE was incorporated with 1 wt.% of hexachlorocyclotriphosphazene (HCCP), thus indicating that HCCP has a good fire-retardant properties. The result showed that all the compounds have good agreement in their LOI values. Compound 4i with a nitro terminal group gave the highest LOI value of 28.37%.
    Matched MeSH terms: Calorimetry, Differential Scanning
  14. Fulltext Lyophilized Amorphous Dispersion of Telmisartan in a Combined Carrier-Alkalizer System: Formulation Development and In Vivo Study
    Al-Japairai KAS, Alkhalidi HM, Mahmood S, Almurisi SH, Doolaanea AA, Al-Sindi TA, et al.
    ACS Omega, 2020 Dec 22;5(50):32466-32480.
    PMID: 33376884 DOI: 10.1021/acsomega.0c04588
    Telmisartan suffers from low oral bioavailability due to its poor water solubility. The research work presents a formulation of solid dispersed (SD) telmisartan formulation as a ternary mixture of a drug, a polymeric carrier (poly(vinylpyrrolidone) (PVP) K30), and an alkalizer (Na2CO3). The preparation method, which was lyophilization of an aqueous solution containing the ingredients, was free from any organic solvent. The developed SD formulations resulted in a significant improvement in in vitro dissolution (>90% drug dissolution in 15 min) compared to pure telmisartan. Solid-state characterization by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) studies indicated the conversion of crystalline telmisartan into an amorphous form. Fourier transform infrared (FTIR) spectroscopy revealed the drug-polymer interaction that was responsible for reducing the chances of recrystallization. A short-term stability study showed that selected SD formulations were stable in terms of in vitro dissolution and retained their amorphous structure in ambient and accelerated conditions over 2 months. Selected formulations (drug/PVP K30/Na2CO3 as 1:1:2 or 1:2:2 weight ratio) resulted in >2.48 times relative oral bioavailability compared to marketed formulations. It was considered that the incorporation of an alkalizer and a hydrophilic polymer, and amorphization of telmisartan by lyophilization, could enhance in vitro dissolution and improve oral bioavailability.
    Matched MeSH terms: Calorimetry, Differential Scanning
  15. Mechanical and thermal properties of hydroxyaptite filled poly (methyl methacrylate) heat processed denture base material
    Mohamed SH, Arifin A, Mohd Ishak ZA, Nizam A, Samsudin AR
    Med J Malaysia, 2004 May;59 Suppl B:25-6.
    PMID: 15468801
    The aim of this study was to evaluate the effect of powder-to-liquid ratio on the glass transition temperature (Tg) and the tensile properties of denture base material prepared from poly (methyl methacrylate) (PMMA) and hydroxyapatite (HA) previously treated with 3-trimethoxysilylpropyl methacrylate (gamma-MPS). Specimens for mechanical testing were prepared by adding composites powder (PMMA, BPO and HA) to the monomer (MMA and EGDMA) followed by hand mixing as in dental laboratory description usage. The glass transition temperature was studied by using differential scanning calorimetry (DSC). It was observed that the tensile properties and the Tg were affected by the powder-to-liquid ratio. The mechanical characterization of the materials were performed by using single edge notch-tension (SEN-T) specimens; the fracture toughness was slightly higher in formulation which contained HA filler compared to commercial denture base material.
    Matched MeSH terms: Calorimetry, Differential Scanning
  16. Mechanical, thermal and chemical resistance of epoxidized natural rubber toughened polylactic acid blends
    Mat Uzir Wahi, Azman Hassan, Akos Noel Ibrahim, Nurhayati Ahmad Zawawi, Kunasegeran K
    Sains Malaysiana, 2015;44:1615-1623.
    Polylactic acid (PLA)/Epoxidized natural rubber (ENR-50) blends were prepared by melt extrusion followed by injection
    molding to fabricate the test samples. The effect of ENR-50 loadings on the morphological, mechanical, chemical
    resistance and water absorption properties of the blends were studied using standard methods. The toughness of the
    blend improved with ENR loading up to 20 wt. % but flexural and tensile strength decreased. The balanced mechanical
    properties were obtained at 20 wt. % ENR-50 loading. SEM showed good distribution and increased ENR particle size
    as ENR content increased from 10 to 30 wt. %. The differential scanning calorimeter (DSC) showed a steady drop in
    crystallization temperature (Tc
    ) as ENR content increases while the glass transition temperature (Tg
    ) remained unchanged.
    Water absorption was observed to increase with ENR loadings. Increase in ENR content was also observed to reduce the
    chemical resistance of the blends.
    Matched MeSH terms: Calorimetry, Differential Scanning
  17. Fulltext Mechanical, thermal and morphological properties of poly(lactic acid)/epoxidized palm olein blend
    Silverajah VS, Ibrahim NA, Zainuddin N, Yunus WM, Hassan HA
    Molecules, 2012 Oct 08;17(10):11729-47.
    PMID: 23044711 DOI: 10.3390/molecules171011729
    Poly(lactic acid) (PLA) is known to be a useful material in substituting the conventional petroleum-based polymer used in packaging, due to its biodegradability and high mechanical strength. Despite the excellent properties of PLA, low flexibility has limited the application of this material. Thus, epoxidized palm olein (EPO) was incorporated into PLA at different loadings (1, 2, 3, 4 and 5 wt%) through the melt blending technique and the product was characterized. The addition of EPO resulted in a decrease in glass transition temperature and an increase of elongation-at-break, which indicates an increase in the PLA chain mobility. PLA/EPO blends also exhibited higher thermal stability than neat PLA. Further, the PLA/1 wt% EPO blend showed enhancement in the tensile, flexural and impact properties. This is due to improved interaction in the blend producing good compatible morphologies, which can be revealed by Scanning Electron Microscopy (SEM) analysis. Therefore, PLA can be efficiently plasticized by EPO and the feasibility of its use as flexible film for food packaging should be considered.
    Matched MeSH terms: Calorimetry, Differential Scanning
  18. Fulltext Mechanism-based selection of stabilization strategy for amorphous formulations: Insights into crystallization pathways
    Edueng K, Mahlin D, Larsson P, Bergström CAS
    J Control Release, 2017 06 28;256:193-202.
    PMID: 28412224 DOI: 10.1016/j.jconrel.2017.04.015
    We developed a step-by-step experimental protocol using differential scanning calorimetry (DSC), dynamic vapour sorption (DVS), polarized light microscopy (PLM) and a small-scale dissolution apparatus (μDISS Profiler) to investigate the mechanism (solid-to-solid or solution-mediated) by which crystallization of amorphous drugs occurs upon dissolution. This protocol then guided how to stabilize the amorphous formulation. Indapamide, metolazone, glibenclamide and glipizide were selected as model drugs and HPMC (Pharmacoat 606) and PVP (K30) as stabilizing polymers. Spray-dried amorphous indapamide, metolazone and glibenclamide crystallized via solution-mediated nucleation while glipizide suffered from solid-to-solid crystallization. The addition of 0.001%-0.01% (w/v) HPMC into the dissolution medium successfully prevented the crystallization of supersaturated solutions of indapamide and metolazone whereas it only reduced the crystallization rate for glibenclamide. Amorphous solid dispersion (ASD) formulation of glipizide and PVP K30, at a ratio of 50:50% (w/w) reduced but did not completely eliminate the solid-to-solid crystallization of glipizide even though the overall dissolution rate was enhanced both in the absence and presence of HPMC. Raman spectroscopy indicated the formation of a glipizide polymorph in the dissolution medium with higher solubility than the stable polymorph. As a complementary technique, molecular dynamics (MD) simulations of indapamide and glibenclamide with HPMC was performed. It was revealed that hydrogen bonding patterns of the two drugs with HPMC differed significantly, suggesting that hydrogen bonding may play a role in the greater stabilizing effect on supersaturation of indapamide, compared to glibenclamide.
    Matched MeSH terms: Calorimetry, Differential Scanning
  19. Fulltext Microcapsules Filled with a Palm Oil-Based Alkyd as Healing Agent for Epoxy Matrix
    Shahabudin N, Yahya R, Gan SN
    Polymers (Basel), 2016 Apr 06;8(4).
    PMID: 30979216 DOI: 10.3390/polym8040125
    One of the approaches to prolong the service lifespan of polymeric material is the development of self-healing ability by means of embedded microcapsules containing a healing agent. In this work, poly(melamine-urea-formaldehyde) (PMUF) microcapsules containing a palm oil-based alkyd were produced by polymerization of melamine resin, urea and formaldehyde that encapsulated droplets of the suspended alkyd particles. A series of spherical and free-flowing microcapsules were obtained. The chemical properties of core and shell materials were characterized by Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and proton nuclear magnetic resonance spectroscopy (¹H-NMR). Differential scanning calorimetry (DSC) analysis showed a glass transition around -15 °C due to the alkyd, and a melting temperature at around 200 °C due to the shell. Thermogravimetric analysis (TGA) results showed that the core and shell thermally degraded within the temperature range of 200⁻600 °C. Field emission scanning electron microscope (FESEM) examination of the ruptured microcapsule showed smooth inner and rough outer surfaces of the shell. Flexural strength and microhardness (Vickers) of the cured epoxy compound were not affected with the incorporation of 1%⁻3% of the microcapsules. The viability of the healing reactions was demonstrated by blending small amounts of alkyd with epoxy and hardener at different ratios. The blends could readily cure to non-sticky hard solids at room temperature and the reactions could be verified by ATR-FTIR.
    Matched MeSH terms: Calorimetry, Differential Scanning
  20. Microwave modified non-crosslinked pectin films with modulated drug release
    Anuar NK, Wong TW, Taib MN
    Pharm Dev Technol, 2012 Jan-Feb;17(1):110-7.
    PMID: 20958167 DOI: 10.3109/10837450.2010.522584
    The effects of microwave on drug release properties of pectin films carrying sulfanilamide (SN-P), sulfathiazole (ST-P) and sulfamerazine (SM-P) of high to low aqueous solubilities were investigated. These films were prepared by solvent evaporation technique and treated by microwave at 80 W for 5-40 min. Their profiles of drug dissolution, drug content, matrix interaction and matrix crystallinity were determined by drug dissolution testing, drug content assay, differential scanning calorimetry, X-ray diffractometry and scanning electron microscopy techniques. Microwave induced an increase in matrix amorphousness but lower drug release propensity with a greater retardation extent in SN-P films, following a rise in strength of matrix interaction. A gain in amorphous structure does not necessarily increase the drug release of film. Microwave can possibly retard drug release of pectin film carrying water-soluble drug through modulating its state of matrix interaction.
    Matched MeSH terms: Calorimetry, Differential Scanning
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