Low-density Polyethylene Terephthalate Research Articles

Effect of Fluid-Structure Interaction on Noise Generation in MAV with Fixed and Flapping Membrane Wing

An experimental study on the effect of fluid-structure interaction on noise generation in Micro Air Vehicle (MAV) with fixed and flapping membrane Tipula sp. wing is investigated. The acoustic performance of the fixed and flapping wing which made up of certain characteristic thin materials such as Low-density Polyethylene Terephthalate (PET), Thin Aluminium sheets (Al), and Non-woven fabrics (NWF) is analysed. An acoustic study is conducted to estimate the acoustic characteristic parameters of the insect mimic- membrane wing for various flapping conditions with various flapping frequency. In this research, the membrane wing with15cm of the total span is tested on both fixed and flapping MAV at different flexibility conditions and velocity conditions. The study of flapping MAV enables the study of the characteristic effects of sound emitted during the flapping motion of a wing. With the analysed results, the performance of wings is identified and compared with the sound pressure level. After analysing different materials, it is found that NWF produces 20% less noise than the other two more materials. Since the stiffness to strength ratio of metal is high, the formation of vortices is less compared to other membranes. For all fixed membrane wings at low Strouhal numbers, the formation of vortices is very low, and when the Strouhal number increases, the vortices became dense and results in the reduction of Sound pressure level.

Effect of Storage Conditions and Packaging Materials on Quality Parameters of Curcuminoids Impregnated Coconut and Raw Banana Slices

Effect of storage conditions and packaging materials on quality parameters of curcuminoids infused coconut and raw banana slices were studied. Moisture sorption study was conducted for the developed products in selected packaging materials namely polypropylene (PP), polyethylene terephthalate (PET)/low density polyethylene terephthalate (LDPE) and metallized PET/LDPE, under ambient and accelerated storage conditions for 90 days. The changes in physical, chemical and sensory parameters of the products were studied during the storage period. The results indicated that 40% relative humidity was critical for storage of products, above which the products required a good moisture barrier to achieve the enhanced shelf-life of the products. In accelerated storage conditions, the moisture content exceeded the critical moisture content for coconut and raw banana slices within 30 days and 15 days, respectively leading to product deterioration. At the end of the storage period the coconut samples packed in PP and PET/LDPE crossed the critical moisture content (3.05%) at ambient storage conditions, whereas, the moisture content of raw banana samples was within the moisture tolerance limit (11.5%). The curcuminoids retention, chroma and total color difference (DE) were significantly higher with better sensory attributes for products packed in metallized PET/LDPE compared to PET/LDPE and PP. Among all the packaging materials studied metallized PET/LDPE was found to be a suitable packaging material for both products. PRACTICAL APPLICATIONS The present work deals with the effect of packaging material on physical, chemical and sensory parameters on the products (curcuminoids impregnated coconut and raw banana slices) infused with bioactive compounds. The study reveals the criteria for the selection of packaging materials as well as storage conditions for curcuminoids impregnated coconut and raw banana slices for the higher retention of bioactive compounds, besides fulfilling consumer desire, satisfying industry requirement and maintaining food safety.

FTIR spectroscopy supported by statistical techniques for the structural characterization of plastic debris in the marine environment: Application to monitoring studies

We inserted 190 FTIR spectra of plastic samples in a digital database and submitted it to Independent Component Analysis (ICA) to extract the “pure” plastic polymers present. These identified plastics were polypropylene (PP), high density polyethylene (HDPE), low density polyethylene (LDPE), high density polyethylene terephthalate (HDPET), low density polyethylene terephthalate (LDPET), polystyrene (PS), Nylon (NL), polyethylene oxide (OPE), and Teflon (TEF) and they were used to establish the similarity with unknown plastics using the correlation coefficient (r), and the crosscorrelation function (CC). For samples with r<0.8 we determined the Mahalanobis Distance (MD) as additional tool of identification. For instance, for the four plastic fragments found in the Carretta carretta, one plastic sample was assigned to OPE due to its r=0.87; for all the other three plastic samples, due to the r values ranging between 0.83 and0.70, the support of MD suggested LDPET and OPE as co-polymer constituents.

Mass Transport of Cell Gases in Carbon Dioxide Blown PET (Polyethylene Terephthalate) Foam Insulation

Polyethylene terephthalate (PET) foam is a possible replacement option for polyurethane (PUR) foam as insulation material in district heating pipes. In this study, the diffusion coefficients and activation energies of cell gases in carbon dioxide blown PET foam (densities 148–157 kg·m−3) were determined at temperatures between 23 °C and 90 °C. The foam thermal ageing due to the mass transport of air into and carbon dioxide out of the foam was about ten times slower in PET foam than in PUR foam. The thermal conductivities of the PET foam boards were determined in a heat flow meter apparatus. The contribution to the foam thermal conductivity due to conduction in the solid polymer and radiation within the cell voids was determined to 17 mW·m−1·K−1 at 20 °C. This is higher than the value estimated for PUR foam in district heating pipes, 12 mW·m−1·K−1. This contribution can probably be reduced by developing low density PET foam and reducing the cell size.