Sulfonation of low‐density polyethylene and its impact on polymer properties

Sulfonation of polymers is of great importance for the packaging industry mainly due to its effect on the alteration of surface functionality of polymer films. In this study we customized liquid phase sulfonation of low‐density polyethylene (LDPE) swelling the polymer by using a combination of polar and nonpolar solvents. Swollen polymer was treated with sulfuric acid of varying concentrations with continuous mixing for in‐depth sulfonation of the polymer. Presence of cyclohexane and ethanol, as polar and nonpolar reagents, not only kept the batch under isothermal conditions but also homogenously influenced in‐depth functionalization of LDPE. The durability of the sulfonated polymer was determined by grinding the test samples 30 days after the reaction. Fourier transform‐infrared spectroscopy indicated presence of functional group moieties, which is also supported by increase of 5% and 1.35% in density and sulfur contents of the polymer, respectively. Contact angle measurements indicate 30° decrease in values of the sulfonated polymer which corresponds with decrease in carbon to hydrogen ratio (from 5.9 to 5.3) and increase in sulfur to carbon ratio (up to 0.0184) resulting from the sulfonation of the polymer. Differential scanning calorimetery results indicate almost linear reduction in the crystallinity of LDPE with an increase in acid concentration used for the sulfonation reaction. POLYM. ENG. SCI., 54:2522–2530, 2014. © 2013 Society of Plastics Engineers     

Molecular Weight Determination of Palm Olein Polyols by Gel Permeation Chromatography Using Polyether Polyols Calibration

Natural oil polyols have been intensively developed and successfully used for the production of various polymers, notably polyurethanes. The need to access the average molecular weight (MW) and the MW distribution (MWD) has led to the efforts to have a precise and reliable determination method. A series of commercial polyether polyols, with well‐defined MW, was used as a gel permeation chromatography (GPC) calibration standard to determine the MW of palm olein polyols. This GPC analysis was compared to the one calibrated against the commercially available polystyrene (PS) standards and to the number‐average molecular weight (M_n) obtained via vapor pressure osmometry (VPO) technique. For example, the M_n obtained for palm olein polyol E‐135 calibrated against polyether polyols was 2,537 Da, which was closer to the M_n via VPO (1,618 Da), than the M_n obtained using PS as calibration standards (3,836 Da). Hence, this GPC analysis using polyether polyols as calibration standards can offer reassured determination of MWD of palm olein polyols.     

Prospects of conducting polymer and graphene as counter electrodes in dye-sensitized solar cells

Dye-sensitized solar cells (DSSCs) garner considerable research interest because of high photo-to-electric conversion efficiencies at low production cost. Platinum has been reported as an efficient metal as a counter electrode (CE) in DSSCs for its outstanding electro catalytic performance. However, the high cost and susceptibility to corrosion of Pt are paving the way for exploring new materials to replace Pt as a counter electrode in DSSCs. Various conducting polymers, graphene and conducting polymer-graphene nanocomposites have been found as counter electrodes in DSSCs with remarkable photovoltaic performances. The urge to produce composites or hybrids with nanomaterials is derived from the improvement of photovoltaic performances. This review will focus on the unique physical and chemical properties of conducting polymers and graphene, their individual photovoltaic performances as counter electrodes in DSSCs, followed by the synergistic effect of conducting polymers and graphene in conducting polymer-graphene nanocomposites as counter electrodes in DSSCs. Finally a brief outlook is provided to improve the photovoltaic performance of DSSCs using conducting polymers and graphene-based counter electrodes.     

Vitreous phase coating on glaserite-type alkaline earth silicate blue phosphor BaCa2MgSi2O8:Eu

A simple solid-state reaction was used to apply a vitreous-phase coating onto Eu²⁺-doped BaCa₂MgSi₂O₈ blue-phosphor particles. The vitreous phase was generated by liquid phase sintering at 1200 °C. The coated phosphor exhibited resistant to an acid dispersant. When a small amount of Al and La was added in raw materials, they were incorporated in the vitreous coating phase.     

Orlistat Mitigates Oxidative Stress-Linked Myocardial Damage via NF-κβ- and Caspase-Dependent Activities in Obese Rats

Oxidative stress contributes to major complications of obesity. This study intended to identify whether orlistat could mitigate myocardial damage in obese animal models. The tested rats were divided into two groups and fed either with normal chow (n = 6 per group) or with a high-fat diet (HFD) for 6 weeks to induce obesity (n = 12 per group). Obese rats were further subjected to treatment either with distilled water (OB group) or orlistat 10 mg/kg/day (OB + OR group). Key indices of oxidative stress, inflammation, and apoptosis were assessed using an immunohistochemical-based technique and real-time PCR. The OB group showed significant increases of oxidative stress markers (TBARs and PCO), with significant decreases of anti-oxidant markers (Nrf2, SOD, CAT, and GPx). Furthermore, mRNA expression of pro-inflammatory markers (TNF-α and NF-κβ) and pro-apoptosis markers (Bax, Caspase-3, Caspase-8, and Caspase-9) were significantly upregulated in the OB group. Obese rats developed pathological changes of myocardial damages as evidenced by the presence of myocardial hypertrophy and inflammatory cells infiltration. Orlistat dampened the progression of myocardial damage in obese rats by ameliorating the oxidative stress, and by inhibiting NF-κβ pathway and caspase-dependent cell apoptosis. Our study proposed that orlistat could potentially mitigate oxidative stress-linked myocardial damage by mitigating inflammation and apoptosis, thus rationalizing its medical usage.     

Rheological Properties and Emulsifying Activity of Gum Karaya (Sterculia Urens) in Aqueous System and Oil in Water Emulsion: Heat Treatment and Microwave Modification

Gum karaya is a polysaccharide gum from Sterculia urens tree. It is used as an emulsifier and thickening agent in cosmetics and pharmaceuticals. However, it has very strong swelling properties, high viscosity, and low solubility, providing the restricted applications in the food industry. The main objective of this study was to investigate the effects of different heat treatment and microwave variables (i.e., time: 8, 10, and 12 min; power: 700 and 1000 W) on the functional properties of gum karaya in the aqueous system and oil-in-water emulsion. In this regard, the rheological properties, emulsifying activity, average droplet size, and surface morphology of the native- and microwave-treated gums were analyzed and compared. Dynamic oscillatory test indicated that the microwave-treated gum karaya had more gel-like behavior than viscous-like behavior (G′ > G″) at a relatively high concentration (20% or 20 g/100 g). When gum karaya was treated by microwave for 8–12 min, both elastic (G′) and viscous (G″) moduli were declined. The native- and microwave-treated gum karaya exhibited a shear-thinning (pseudoplastic) behavior in the aqueous system and oil-in-water emulsion. The results showed that the microwave-treated gum karaya had smaller particles than the native gum in the aqueous system. On the other hand, the emulsion containing the microwave-treated gum karaya had finer emulsion droplets than the control containing the native gum karaya. This confirmed that the application of microwave treatment led to significantly (p < 0.05) improve the emulsifying activity of gum karaya.     

The use of cooling and heating thermograms for monitoring of tallow, lard and chicken fat adulterations in canola oil

The use of cooling and heating thermograms from differential scanning calorimetry (DSC) for monitoring the presence of genuine lard (GLD), beef tallow (BT), chicken fat (CF) as adulterants in canola oil has been investigated. Mixing of animal fats especially lard and tallow in any form in food products is a cause of concern for certain religions. Canola oil samples spiked separately with BT, GLD and CF in levels ranging from 1 to 20% (w/w) were analysed by DSC to obtain their cooling and heating profiles. The heating measurements showed that detection of GLD and BT adulterations could be possible based on characteristic differences of GLD and BT adulteration peaks appearing in the higher temperature region of heating thermograms while cooling measurements showed that BT adulteration could be determined by a distinct exothermic peak appearing in the higher temperature region of the cooling thermograms. The determination of GLD by cooling measurements could not be possible since the changes due to GLD and CF adulterations were very similar.