Mustafa Baysal

Halloysite Nanotubes/Polyethylene Nanocomposites for Active Food Packaging Materials with Ethylene Scavenging and Gas Barrier Properties

Novel polymeric active food packaging films comprising halloysite nanotubes (HNTs) as active agents were developed. HNTs which are hollow tubular clay nanoparticles were utilized as nanofillers absorbing the naturally produced ethylene gas that causes softening and aging of fruits and vegetables; at the same time, limiting the migration of spoilage-inducing gas molecules within the polymer matrix. HNT/polyethylene (HNT/PE) nanocomposite films demonstrated larger ethylene scavenging capacity and lower oxygen and water vapor transmission rates than neat PE films. Nanocomposite films were shown to slow down the ripening process of bananas and retain the firmness of tomatoes due to their ethylene scavenging properties. Furthermore, nanocomposite films also slowed down the weight loss of strawberries and aerobic bacterial growth on chicken surfaces due to their water vapor and oxygen barrier properties. HNT/PE nanocomposite films demonstrated here can greatly contribute to food safety as active food packaging materials that can improve the quality and shelf life of fresh food products.

SYNTHESIS OF MESOPOROUS MCM-41 MATERIALS WITH LOW-POWER MICROWAVE HEATING

Crystalline, high-surface-area, hexagonal mesoporous MCM-41 having uniform pore sizes and good thermal stability was successfully synthesized at 90°–120°C in 30 min using low-power microwave irradiation. This appears to be the first comprehensive and quantitative investigation of the comparatively rapid synthesis of mesoporous MCM-41 using low-power microwave heating of 80 W (90°C) and 120 W (120°C). The influence of reaction temperature and the duration of heating were carefully investigated, and the calcined MCM-41 materials were characterized by XRD, SEM, TEM, nitrogen adsorption, TGA, and FT-IR. The mesoporous MCM-41 product synthesized in 30 min at 120 W and calcined at 550°C had a very high surface area of 1438 m2/g and was highly ordered, containing uniform pores with diameters in the range of 3.5–4.5 nm. The wall thickness of the materials highly depended on the power of the microwave energy used during synthesis. Synthesis of the mesoporous MCM-41 products at 120°C resulted in a structure with thinner walls. The mesoporous MCM-41 materials synthesized in the present work had good thermal stability.

Characterization of bio-oils and bio-char obtained from the pyrolysis of a mixture of Lolium perenne, Festuca ovina, Festuca rubra and Poa pratensis grasses.

ABSTRACT In this work, the yield and chemical characterization of products obtained from the pyrolysis of a mixture of Lolium perenne, Festuca ovina, Festuca rubra and Poa pratensis grasses under an inert atmosphere at 600°C with a heating rate of 50°C/min was studied. Distribution of the products of pyrolysis grass sample was: moisture: 8 ± 2%, total volatiles: 78 ± 7%, char: 14 ± 5%. Bio-oils were acidic and dark brown liquids and they were separated into oils, asphaltenes and asphaltols by solvent extraction procedures prior to gas chromatography-mass spectrometry (GC-MS) analyses. GC-MS results showed that the bio-oils contained complex mixtures of organic compounds, including acetic acid and a large variety of oxygenated and nitrogenated compounds such as phenols, pyridines, pyrazoles, imidazoles, amines, and ketones. SEM micrographs of the bio-chars indicated amorphous, porous and heterogeneous structure of the bio-char obtained from the grass sample. EDX analysis of the bio-char revealed that bio-char contained K, Ca, P and Mg elements.