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In this work, the effect of the non‐isothermal elongational flow on the morphology and mechanical properties of polypropylene (PP)‐based nanocomposites containing Mg‐Al layered double hydroxides (LDHs) modified with stearate or oleate functional groups has been investigated. In particular, nanocomposites containing 5 and 10 wt% of LDHs prepared through melt compounding were subjected to uniaxial elongational flow at the exit of the extruder, leading to the formation of fibers characterized by different draw ratios (DRs). The mechanical characterization of the fibers demonstrated a progressive enhancement of the tensile strength as a function of the DR with increasing the content of nanofillers. Notably, for the fibers stretched at a DR of 200 and containing 10 wt% of LDHs modified with oleate groups, the tensile strength increased fourfold as compared to that of the unfilled matrix. These results have been attributed to a progressive enhancement of the extent of the dispersions of the embedded LDHs induced by the application of the elongational flow, as also confirmed by morphological analyses. In all, the obtained results demonstrated the beneficial effect of the elongational flow in promoting the achievement of superior mechanical properties in LDHs‐containing nanocomposites, hence widening the application field of these nanostructured materials. Highlights: PP/organomodified LDH nanocomposites were obtained through melt compounding.Nonisothermal elongational flow was applied to the extrudates at the die exit.Anisotropic fibers showed progressively enhanced tensile strength values.Elongational flow promoted a gradual evolution of the material microstructure.A gradual improvement of the nanofiller dispersion was observed upon elongation. [ABSTRACT FROM AUTHOR]

In this paper, the possibility of detecting polymers in plastic mixtures and extruded blends has been investigated. Pyrolysis–gas chromatography/mass spectrometry (py-GC/MS) allows researchers to identify multicomponent mixtures and low amounts of polymers without high spatial resolution, background noise and constituents mix interfering, as with molecular spectrometry techniques normally used for this purpose, such as Fourier transform infrared spectroscopy (FTIR) and Raman spectroscopy and differential scanning calorimetry (DSC). In total, 15 solid mixtures of low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), polyamide (PA) and polycarbonate (PC) in various combinations have been qualitatively analyzed after choosing their characteristic pyrolysis products and each polymer has been detected in every mix; thus, in extruded blends of high-density polyethylene (HDPE), PP and PS had varying weight percentages of the individual constituents ranging from 10 up to 90. Moreover, quantitative analysis of these polymers has been achieved in every blend with a trend that can be considered linear with coefficients of determination higher than 0.9, even though the limits of quantification are lower with respect to the ones reported in the literature, probably due to the extrusion process. [ABSTRACT FROM AUTHOR]

Highlights Biocomposites are an emerging field in plastic industry. The incorporation of agri‐food waste in conventional or biobased polymer matrices allows the industry to lessen its carbon footprint, while producing recyclable plastic products. In this work, hemp hurd, a byproduct of hemp fiber production process, was used as a filler to prepare novel compostable composites in two different loadings (22% and 32% w/w respectively). Waste hemp hurds were selected due to their abundance and the lack of derived high‐value products. Three different polymers were used, namely poly[(tetramethyleneadipate)‐co‐(tetramethyleneterephthalate)] (PBAT) and poly(tetramethylene succinate) (PBS) as compostable polymers and a polyethylene elastomer for comparison. The bare polymers and prepared blends were then characterized for their structure and morphology by XRD and FESEM, as well as for their wettability, thermal and mechanical properties (namely energy absorbed on impact and flexural modulus). Structural and morphological characterization unveiled the different interactions occurring between hemp and the polymer matrices, suggesting the major impact of the type of used polymer when compared with biomass loading percentages. Mechanical tests showed that both PBAT and PBS blends properties are comparable to those of the pure polymers (i.e., in the case of PBAT the flexural modulus of the pure polymer was 82.2 MPa while the hemp‐loaded blends stood at around 50 MPa, whereas all PBS polymers and blends were 220 MPa, with no statistical difference between samples). These biomaterials have also similar thermal properties with respect to the bare polymers, underlining the promising potential as sustainable alternative to pure polymers. Waste hemp hurds were used to load biodegradable polymers at different percentages. Hemp hurd‐based biomaterials with excellent properties were prepared. Polymer flexural behavior was maintained even after hemp addition. Polymer‐hemp interactions for each polymeric matrix were elucidated. Hemp substitutes up to 32% w/w of polymer without affecting its properties. [ABSTRACT FROM AUTHOR]