Broccoli (Brassica oleracea L. var. Italica) florets were packaged in low‐density polyethylene (LDPE) bags with or without ethylene adsorber under passive modified atmosphere and then stored at 4°C for 20 days. LDPE films with (8% Tazetut® masterbatch, M2) or without ethylene adsorber (M1) were tested. The effects of modified atmosphere packaging treatments on gas concentrations (O2, CO2 and ethylene) in the headspace, the mass loss, colour, texture, pH, total soluble solids, chlorophyll content, total phenolic content and sensory quality of packaged broccoli were determined by comparing with unpackaged (control) florets. Results revealed that deterioration occurred quickly in control broccoli, manifested mainly by mass loss, chlorophyll degradation and stem hardening. Also, it was found unacceptable by sensory panel after 5 days. Conversely, in those florets packaged under modified atmosphere packaging, especially for LDPE with ethylene adsorber (M2), all changes related with loss of quality were significantly reduced and delayed with time. Additionally, total soluble solids and total phenolic content remained almost unchanged during the whole period. Ethylene concentration was determined as 61.8 ppm in M1 and 0.33 ppm in M2, respectively, at the end of the storage. Thus, broccoli packaged with M2 films had prolonged storability up to 20 days with high quality attributes, this period being only 5 days in unpackaged control broccoli. Oxygen concentration decreased below 1% after 5 days of storage in M1, and the shelf life of broccoli in these bags was limited to 5 days because of risk for anaerobic fermentation. Copyright © 2013 John Wiley & Sons, Ltd.
Thermal, rheological, and physical properties of amorphous poly(ethylene terephthalate) (PET)/organoclay nanocomposite films which were successfully prepared with melt processing method using a PET/organoclay masterbatch were studied in detail. Structural and physical properties of the films were characterized by the UV-Vis spectroscopy, XRD and SEM analysis, DSC, DMA, and rheological tests and gas permeability measurements. Cold-crystallization behavior of the samples was analyzed by the DSC and DMA methods. Aspect ratio of the organoclay layers were determined with the Nielsen and Halpin-Tsai models based on the gas permeability and DMA data, respectively. It was found that the organoclay reduced the nonisothermal cold-crystallization rate of PET chains by restricting the segmental motion of the polymer in the solid state. On the other hand, the organoclay enhanced the nonisothermal melt-crystallization of PET due to the nucleation effect. Aspect ratio (A f ) of the clay layers were found to be about 20 by using the gas permeability and DMA data. Aspect ratio value was also confirmed by the analysis of SEM images of the samples. A physical model for the sample microstructure was offered that the stacks with the thickness of 20-30 nm and the lateral size of 400-600 nm, probably consisting of 5-8 layers, were uniformly dispersed in the PET structure.
In this study, the aim was to examine the effects of three different compatibilizers on the recycled polyethylene/ thermoplastic starch (r-LDPE/TPS) blends which are used in producing garbage bags. Polyethylene-Grafted-Maleic Anhydride (PEgMAH), maleic-anhydride modified ethylene propylene rubber (EPMgMAH) and ethylene maleic anhydride copolymer (PEMAH) were selected as the compatibilizers. r-LDPE/TPS blends with or without compatibilizer were prepared by using a twin screw extruder and characterized by means of mechanical, thermal, structural and morphological analyses. It was found that tensile strength values increased with the addition of PEgMAH but decreased with the addition of EPMgMAH. Elongations at break values of the r-LDPE/TPS blends were significantly improved by using PEgMAH and EPMgMAH. Tm and Tc values have slightly affected by the compatibilizer usage in the DSC analysis. In addition, the better interfacial interaction was observed for the compatibilized blend with the PEgMAH and EPMgMAH during the SEM analysis. It was concluded that PEgMAH and EPMgMAH showed mainly changed results in elongation at break values and this is the important parameter in the packaging industry.
Until now, recycling studies brought to the agenda after the rapid increasing of plastic materials in every area and causing those plastics to environmental pollution after discarding them following the utilization. The purpose of recycling plastic waste is to minimize environmental pollution and to create of new resources. To perform the present study, Recycled Polypropylene Granules (RPP) belonging to Polypropylene (PP) will be used in most particularly in the automotive and in the packaging industry finding application area behind the Low Density Polyethylene (LDPE). To develop the several properties (physical and thermal) of RPP polymer and to get close to or greater value to the original PP features, different rates of micron-sized glass fibers, talc and CaCO 3 are added into the polymer. By recycling waste, demand for natural resources (such as oil, which is plastic's raw materials) will decrease and rapid consumption of energy sources will be prevented while providing the protection of natural resources. Raw materials imports would be reduced due to the usage of recycled products. In this study, Recycled Polypropylene Granules (RPP) were obtained from companies and glass fiber/talc/CaCO 3 additive RPP granules in different ratios were produced with compounding extrusion process. These produced new composite pellets were produced in injection molding machine by means of designed mold to perform tensile and impact tests. In the thermal analysis, the melting temperature and crystallization rate were determined by DSC analysis; the thermal decomposition temperature was determined by TGA analysis. Micro structural examination was done using a Scanning Electron Microscope (SEM).
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