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Poly(meta-phenylene isophtalamide) (PMIA) was processed via electrospinning to provide nanofibrous membranes with randomly and aligned fibers. Mechanical performance of such membranes was evaluated, applying a normalization procedure that takes into account the peculiar morphology of such complex substrate where voids can sum up to almost 80% of the sample volume. Random and aligned fibers membranes are applied onto wood panels to test their fire resistance in cone calorimetry when coated in polyaramidic thin nanofiber mats. Tests highlighted that random fibers provide a better fire protection, increasing Time to Ignition and decreasing the Fire Performance Index. Another important parameter affecting the performance is the adhesive system used to apply the nanofibers onto wood that is able to significantly modify the fire performance of the polyaramidic-coated wood panels., INTRODUCTION Wood is an obvious green and sustainable material: it comes from renewable resources, is biodegradable and in the last years, the environmental concerns and the interesting properties possessed by [...]

Automotive interiors materials, like plasticized polyvinyl chloride (pPVC) synthetic leathers (SLs), require additives for improving their flame behavior. The preferred flame retardant (FR) used in pPVC is antimony trioxide ([Sb.sub.2][O.sub.3], ATO), though the use of antimony poses several issues, for both human health and the environment, related to its extraction, processing, and use. In order to investigate alternatives to ATO in high-performance pPVC SLs, various commercial FRs have been selected and tested in a typical, highly plasticized formulation. These additives have been used either alone or combined to evaluate synergistic effects. Samples have been tested to assess mechanical properties, thermal stability, and flame resistance. Data have been compared with those of neat pPVC and a foil with 2 phr of ATO. Several FRs are effective in improving the flame response compared with neat pPVC, without compromising the other properties, in detail calcium hypophosphite and mixtures containing zinc hydroxystannate (ZHS). Finally, aluminum hydroxide and ZHS (ATH + ZHS) yields the cheaper among the alternatives here proposed, even though higher than ATO (+193%) whose price/performance ratio is difficult to overcome., INTRODUCTION While plastic materials are presently widely employed in almost all the application fields, one of their major drawbacks is indeed their ease of burning. In order to avoid or [...]

The recycling of carbon fibers (CFs) from composites is becoming a necessity, with a gain both from economic and environmental point of views because carbon fibers are a high value‐added material and the energy requirement for their production is pretty high. The use of such recycled fibers needs to find reliable applications to fully close the circular economic loop and here it is demonstrated that their applications as short fiber reinforcement in thermoplastics are not only convenient but as reliable as prostin fibers. This work wants to evaluate the effect of the recycling and reprocessing recycled carbon fibers versus pristine fibers, when inserted in polyprolylene (PP), in the presence of different amounts of compatibilizer to promote a better fiber/matrix interaction. [ABSTRACT FROM AUTHOR]

The present paper introduces a preliminary analysis and the recent development of three‐dimensional (3D) printed thermoplastic polyurethane (TPE‐U) as a replacement of polyurethane (PU) foams that has led to a recyclable product. Among the various 3D printing techniques available, the team focuses on Fused Deposition Modeling (FDM) because of its simplicity, affordability, and versatility in printing geometries and recyclability of materials. Four thermoplastic polyurethane (TPU) elastomers with different stiffness (in the range of Shore A) are used. Therefore, through the combination of different printing geometries, modulation of the main printing parameters, and different materials, an attempt is made to simulate the mechanical behavior of PU foams, which are commonly used for the production of paddings. The mechanical evaluation, by means of dynamic mechanical analysis (DMA), of the of 3D printed specimens has highlighted a qualitatively different and potentially superior behavior with respect to that of PU foam. [ABSTRACT FROM AUTHOR]

This work compares the delamination behavior of epoxy CFRPs nano‐modified with nitrile butadiene rubber/polyethylene oxide (NBR/PEO) blend nanofibrous membranes with a rubber content of 70 wt%. While the electrospun mat is able to retain the nanofibrous structure even without crosslinking, photocrosslinking is also carried to evaluate the potential different efficacy on the delamination hindering. Double cantilever beam (DCB) and end‐notched flexure (ENF) tests show significant improvements of the energy release rates (G) both in Mode I (up to ≈4 times) and Mode II (up to ≈1.5 times). In particular, the presence of "liquid" rubber (uncrosslinked mat) leads to the best reinforcing action in Mode I, while the crosslinked membrane gives the highest delamination hindering in Mode II. [ABSTRACT FROM AUTHOR]

Carbon fiber reinforced composites (CFRC) are remarkably replacing conventional materials in application requiring high mechanical performance thanks to their light weight and outstanding mechanical properties. Due to the massive increase in their production and application, one of the main drawbacks resides in their disposal, both at the end of their life and as scraps and offcuts. Furthermore, the production of carbon fiber (CFs) requires high energy demand (183–286 MJ kg−1), hence the recovery of composites to reuse CF seems to be a promising option in terms of sustainability and circular economy. With the aim of identifying a methodology to recover and recycle these materials, through this work a case study is shown for optimization of the pyrogasification process. [ABSTRACT FROM AUTHOR]

Rubber containing nanofiber is investigated as structural modifiers of carbon fiber reinforced polymers (CFRPs) to improve their delamination resistance. The ability to obtain long lasting nanofibrous shape from liquid nitrile butadiene rubber (NBR) has been demonstrated even without requiring instant cross‐linking when a second component is used together with NBR in the process. The second component can be a thermoplastic which either melts, such as poly(e‐caprolactone) (PCL), or holds steady, as poly(m‐phenylene isophthalamide) (PMIA) or nylon 66, during CFRP curing process. Assuming that NBR is not crosslinked, during curing of low Tm thermoplastic‐based rubber nanofibers, their morphology is lost, as for NBR/PCL, and both polymers blend with the surrounding epoxy resin thus leading to an outstanding toughening effect, but at the cost of the overall composite mechanical performance. When a second component is used which is preserved in nanofibrous fashion during curing (NBR/PMIA, NBR/nylon 66), instead, a good compromise is achieved, with still outstanding delamination hindering ability, together with almost fully preserved thermo‐mechanical performances. [ABSTRACT FROM AUTHOR]

Delamination is a common failure mechanism affecting composite laminates. Thermoplastic poly(ethylene oxide) (PEO) nanofibers are recently proposed for toughening carbon fiber reinforced polymers (CFRPs), obtaining promising results. In the present work, PEO‐modified epoxy CFRPs underwent ageing in water for 1 month, and the interlaminar properties are assessed via double cantilever beam (DCB) and end‐notched flexure (ENF) tests. The Mode I delamination behavior of both PEO‐modified and unmodified commercial composite plates is compared. Water ageing slightly affects the mechanical properties of the nano‐modified laminates, though the interleaved nano‐reinforcement is water‐soluble. The achieved results are very encouraging and pave the way to the use of PEO nanofibrous mats for hindering delamination in composite laminates. [ABSTRACT FROM AUTHOR]

The present paper aims at the investigation of the nature and possible origin of solid residues found in the washing basins of Ultrasonic Mould Cleaning System (UMCS) plants. In particular, analyses have been focused on the potential PTFE provenience of the debris and the eventual effect of acid solutions used in the process. Moreover, spring vents taken apart from tyre moulds subjected to repeated use and cleaning cycles, have been analysed in order to determine signs of wear, damage extent and its possible causes. Analyses have been performed by means of FT-IR, TGA, SEM-EDX and XRF, obtaining information on both organic and inorganic fractions. Results obtained seem to indicate that the degradation of PTFE is not responsible of the presence of these debris, and the acid solutions used in the process appear not to have a significant or direct role in the degradation and oxidation patterns.

Glass fiber-reinforced polyester composite (GFRPs) scraps from manufacturing of polyester laminates were pyrolyzed at 500, 550 and 600°C in an 70 Kg innovative batch pilot plant that processes whole parts. The presence of a hydraulic guard guarantees the safety of the process. The influence of the maximum process temperature on yields and chemical-physical properties of pyrolysis products was investigated: the oil fraction was analysed by GC-MS, Viscometer and XRF, while the gas fraction was monitored online during the entire pyrolysis process by µ-GC. Substantial fractions of methane (20.7 vol %) and hydrogen (11.5 vol %) were produced. The solid residue (glass fibers covered by a thin carbonaceous layer) underwent an oxidative process at 500 and 600°C at different residence times to provide clean glass fibers free of organic residues. The effects of both pyrolysis and oxidative step on the glass fibers, obtained in different process conditions, were evaluated by SEM and Raman spectroscopy.

New flame retardant organo-modified bentonites, based on nitrogen-containing compounds were synthesized via an ion exchange process starting from pristine bentonite with acidified 6-(4-butylphenyl)-1,3,5-triazine-2,4-diamine (BFTDA) and 11-amino-N-(pyridine-2yl)undecanamide (APUA). The amount of nitrogen rich organic modifier in the obtained organoclays (Bento-BFTDA and BentoAPUA) determined by TGA is around 0.4 mmol/g for both samples. With the aim to study the effect of these additives on a commercial epoxy resin, nanocomposites containing 3 and 5 wt% of the nanofillers were prepared by solventless addition to the epoxy resin formulation. For the sake of comparison similar nanocomposites with plain unmodified bentonite were produced. The nanocomposite's thermo-mechanical properties of all the produced samples were measured and they resulted slightly improved or practically unaffected. Finally, when the flame behavior was assessed in the cone-calorimeter, an encouraging decrease of 17% in the peak heat released rate (pHRR) was obtained at 3 wt% loading level with Bento-APUA. These promising results suggest that the APUA modified organoclay, prepared with low cost reactants and mild reaction conditions, might efficiently act as a flame retardant., INTRODUCTION In the last century, polymeric materials have greatly changed the world we live in, joining or replacing traditional metallic and natural materials. Composite materials, in particular, took steel and [...]

During last decades, implantable drug delivery systems (DDS) have been developed to optimize therapeutic properties of drugs and ensure their release in a specific site. Acrylic polymers have obtained growing interest in biomedical applications for their biocompatibility and chemical properties that make them extremely versatile. In this work, we focused on the realization of polymeric systems for controlled and sustained release of betamethasone 17,21-dipropionate (BDP), a corticosteroid drug, in the treatment of the posterior eye diseases (PED). The investigated DDS were made of opportunely designed methacrylic block copolymers. Different series of methylmethacrylate/2-hydroxyethylmethacrylate (MMA/HEMA) block copolymers, with various monomeric compositions (20-60 mol% HEMA), were synthetized by Atom Transfer Radical Polymerization to find the best hydrophilic/hydrophobic ratio, able to ensure optimal kinetic release. Copolymers were characterized by nuclear magnectic resonance, size exclusion chromatography, and differential scanning calorimetry. Monitoring of drug release from films loaded with BDP was carried out by HPLC analysis. In particular, PMMA-b-PHEMA with 47 mol% of HEMA showed the best release profile to achieve the therapeutic reference dose, used in the treatment of PED (1-3 [micro]g/day), up to four months. Additionally, intraocular inserts with different shapes were prepared using silicon molds made by means of a 3D printer., INTRODUCTION Ocular diseases affect both the anterior and posterior segment of the eye. The most important posterior eye diseases (PED). that cause visual impairment, include age-related macular degeneration, macular edema [...]