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a b s t r a c tThe development of crystalline lamellae in ultra-thin layers of poly(ethylene terephthalate) PET confined between polycarbonate (PC) layers in an alternating assembly is investigated as a function of layer thickness by means of X-ray diffraction methods. Isothermal crystallization from the glassy state is insitu followed by means of small-angle X-ray diffraction. It is found that the reduced size of the PET layers influences the lamellar nanostructure and induces a preferential lamellar orientation. Two lamellar populations, flat-on and edge-on, are found to coexist in a wide range of crystallization temperatures (T c ¼ 117e150 C) and within layer thicknesses down to 35 nm. Flat-on lamellae appear at a reduced crystallization rate with respect to bulk PET giving rise to crystals of similar dimensions separated by larger amorphous regions. In addition, a narrower distribution of lamellar orientations develops when the layer thickness is reduced or the crystallization temperature is raised. In case of edgeon lamellae, crystallization conditions also influence the development of lamellar orientation; however, the latter is little affected by the reduced size of the layers. Results suggest that flat-on lamellae arise as a consequence of spatial confinement and edge-on lamellae could be generated due to the interactions with the PC interface.

The use of recycled plastics in applications similar to those of the original plastic is of great interest for the fulfillment of the circular economy policies objectives. In this work, the feasibility of using recycled agricultural plastics in the manufacture of tube shelters for plant seedlings, which can be used in forest restoration and other plantations, has been investigated.The recycled plastics and their blends with a virgin polyethylene were characterized using spectroscopic techniques and thermal analysis. The effects of the recycled plastics on the optical and mechanical properties of the blends, which are key properties in the selection of materials for tube shelters, were measured using UV-Vis spectroscopy and tensile testing. Thermal stability and degradation during an accelerated aging test were also investigated. The use of recycled plastics did not alter the stability of the blends, but there were decreases in elongation at break and UV and blue light transmission, with small decreases in red light transmission and without significant changes in the red-far red ratio. Blends with less than 50 wt% of recycled plastics show only small decreases in the elongation and provide an adequate light transmission for seedlings. Therefore, the results indicate that significant amounts of recycled agricultural plastics can be used in the manufacture of tube shelters, with clear environmental advantages.