Mechanical and thermal properties of crab chitin reinforced carboxylated SBR composites

The addition of small amounts (up to 9 wt%) of chitin microsized particles, originating from shellfish waste, to carboxylated styrene-butadiene rubber (XSBR) matrix (as received and annealed to 100°C) has been studied. In particular, this study concentrated on their mechanical (creep investigation by nanoindentation and dynamical-mechanical analysis), thermal (differential scanning calorimetry and thermogravimetry) and swelling behaviour (toluene absorption) and was completed by morphological characterisation by scanning electron microscopy and atomic force microscopy. The results show that annealing has a limited effect on materials properties, effects which are further reduced by the addition of growing amounts of crab chitin. It should be noted that the limited filler content used in the study does not substantially modify the linear creep behaviour of XSBR for sufficiently long loading times. The thermal stability of the system does also appear to be preserved even with the maximum chitin content added, while it serves sufficiently as an effective barrier against aromatic solvent absorption

A comparative study on the reactive compatibilization of melt-processed polyamide 1010/polylactide blends by multi-functionalized additives derived from linseed oil and petroleum

[EN] This research work describes the manufacturing and characterization of novel engineering materials consisted of fully bio-based blends of polyamide 1010 (PA1010) with 20 wt% of polylactide (PLA). Four different compatibilizers were used to enhance the miscibility and the performance of the biopolymer blends. Two multi-functionalized vegetable oils (maleinized linseed oil (MLO) and epoxidized linseed oil (ELO)) and two petroleum-derived glycidyl-based additives (epoxy styrene-acrylic oligomer (ESAO) and styrene-glycidyl methacrylate copolymer (PS-GMA)) were tested during melt compounding. The resultant biopolymer blends were processed by either cast film extrusion or injection molding to obtain films and pieces, respectively. Thin films with an average thickness of 50¿60 µm and thick pieces of 4 mm were obtained, and their mechanical, morphological, thermal, thermomechanical, barrier and, optical properties were characterized. Although all four compatibilizers successfully provided compatibilization to the blends, the chemically modified vegetable oils, that is, MLO and ELO yielded the injection-molded pieces with the most balanced mechanical properties in terms of strength and toughness. Besides, the resultant films showed very low oxygen transmission rate values, thus broadening the potential of these biopolymer blends for the food packaging industryThis research work was funded by the Spanish Ministry of Science, Innovation, and Universities (MICIU) project numbers MAT2017-84909-C2-2-R and AGL2015-63855-C2-1-R. Quiles-Carrillo and Torres-Giner are recipients of a FPU grant (FPU15/03812) from the Spanish Ministry of Education, Culture, and Sports (MECD) and a Juan de la Cierva contract (IJCI-2016-29675) from MICIU, respectively. Microscopy services at UPV are acknowledged for their help in collecting and analyzing FESEM images. Authors thank Polyscope for kindly supplying XibondTM 920 for this study.Quiles-Carrillo, L.; Fenollar, O.; Balart, R.; Torres-Giner, S.; Rallini, M.; Dominici, F.; Torre, L. (2020). A comparative study on the reactive compatibilization of melt-processed polyamide 1010/polylactide blends by multi-functionalized additives derived from linseed oil and petroleum. eXPRESS Polymer Letters. 14(6):583-604. https://doi.org/10.3144/expresspolymlett.2020.48S58360414

Interrupted quenching in high carbon steels for forgings

The present study is focused on analyzing the effect of the interrupted quenching followed by a partitioning process in a high carbon steel 0,50 % C, 1,50 % Mn, 0,40 % Si, 2,00 % Cr without significant contribution of Al. Thermal treatments were performed at laboratory scale in a quenching dilatometer Linseis R.I.T.A RL78. The fractions of retained austenite were evaluated by scanning electron microscope. The temperature for the interrupted quenching phase was evaluated based on the Koistenen and Marburger equation (adapted to the 0,50 % C steel) and the result highlights a correlation between the chosen different temperature of quenching and the fraction of retained austenite formed during the quenching step of the process

Thermal treatment of magnesium particles in polylactic acid polymer films elicits the expression of osteogenic differentiation markers and lipidome profile remodeling in human adipose stem cells

The efficacy of polylactic acid (PLA)/Magnesium (Mg)-based materials for driving stem cells toward bone tissue engineering applications requires specific Mg surface properties to modulate the interface of stem cells with the film. Here, we have developed novel PLA/Mg-based composites and explored their osteogenic differentiation potential on human adipose stem cells (hASCs). Mg-particles/polymer interface was improved by two treatments: heating in oxidative atmosphere (TT) and surface modification with a compatibilizer (PEI). Different contents of Mg particles were dispersed in PLA and composite surface and bulk properties, protein adsorption, stem cell-PLA/Mg interactions, osteogenic markers expressions, and lipids composition profile were evaluated. Mg particles were uniformly distributed on the surface and in the bulk PLA polymer. Improved and modulated particle-polymer adhesion was observed in Mg particle-treated composites. After 21 days in canonical growth culture conditions, hASCs on PLA/MgTT displayed the highest expression of the general osteogenic markers, RUNX2, SSP1, and BGLAP genes, Alkaline Phosphatase, type I Collagen, Osteopontin, and Calcium deposits. Moreover, by LC/MS QTOF mass-spectrophotometry lipidomic analysis, we found in PLA/MgTT-cells, for the first time, a remodeling of the lipid classes composition associated with the osteogenic differentiation. We ascribed these results to MgTT characteristics, which improve Mg availability and composite osteoinductive performance.This work has been carried out within the M-ERANET Programme: Project POLYMAGIC. A. Ferrandez-Montero thanks Project ADITIMAT-CM: Fabricación aditiva: del material a la aplicación. S2018/NMT-4411. M. Lieblich thanks Project PID2019-104351GB-C21 financed by MCIN/AEI/10.13039/501100011033

Tensile and fatigue characterisation of textile cotton waste/polypropylene laminates

Abstract Short fibre based cotton flocks from end-of-life jeans fabric (denim twill weave) were introduced in an amount of 16 wt.% in a polypropylene (PP) matrix using a specifically designed manufacturing process to preserve as much as possible the properties of the cotton waste during injection moulding. This involved a first phase of binding the cotton flocks on polyvinyl acetate (PVAc) support, then pelletizing them with PP and finally extruding the final composite. The resulting composites were subjected to morphological, tensile and fatigue characterisation with stress levels from 50 to 90% of ultimate tensile strength. Results indicated that injection moulding offered a sufficient uniformity of properties to the composite, albeit with some occurrence of pull-out during loading. In particular, the tensile performance exceeded that of the pure matrix in a measure compatible with the amount of fibres introduced. In addition, tensile fatigue loading up to 5000 cycles evidenced a limited amount of degradation for maximum applied stresses up to 70% of composite tensile strength

Analysis and simulation of the electrical properties of CNTs/epoxy nanocomposites for high performance composite matrices

Carbon fiber composite laminates have good electrical properties due to the performance of the fibers, but the composite anisotropy induces a quite lower conductivity through the thickness. In fact, in this direction the fiber bundles are separated by insulating epoxy matrix. In this work, CNTs (carbon nanotubes) with different geometries and functionalization have been added to an epoxy resin to improve the electrical performance. The nanofilled matrix has been used to produce carbon fiber (CF) composites for aerospace applications. Multiscale modeling was used to predict some important parameters such as percolation threshold and the model has been successfully verified with experimental results. The results reported show a good improvement of the electrical and mechanical properties both in the matrix and in the composites. In particular, in composites with the nanocomposite matrix, an improvement of one order of magnitude in the electrical conductivity through the laminate thickness has been achieved.Contract grant sponsor: The European FP7 Project COMPNANOCOMP; contract grant number: 295355; contract grant sponsor: The Ministry of Science and Education of Russian Federation within the frame of the Megagrant; contract grant number: 14.Z50.31.0002; contract grant sponsor: The State Work Quata; contract grant number: 1001140.Peer Reviewe