1,721,099 research outputs found
Bio-based PA5.10 for Industrial Applications: Improvement of Barrier and Thermo-mechanical Properties with Rice Husk Ash and Nanoclay
Full text linkComposites consisting of renewable PA5.10 were obtained from melt compounding with a modified clay (CL) and/or a
by-product obtained from the combustion of rice husk (RHA). Two different industrialized lab-scale machines were used
to obtain the final shape: a film extrusion machine and an injection moulding apparatus. The industrial application requirements
for polyamides generally need good barrier properties and high thermo-mechanical strength. Considering the barrier
properties, the CL was able to decrease the oxygen permeability to less than half with respect to neat PA5.10. DMTA
demonstrated that the addition of RHA caused a consistent enhancement (+ 46 °C) in the heat deflection temperature (HDT)
compared to the neat PA5.10 matrix, increasing the possible areas of interest. Furthermore, the simultaneous presence of
RHA and CL provided the best result reaching an extraordinary HDT of 131 °C. A complete discussion taking into account
the morphology, crystallinity and filler-matrix adhesion evaluation was reported as well as comparison of performances with
other bio-PAs composites. These two fillers can therefore be used separated or together combined in PA5.10 for functional
purposes in a sustainable scenario
Improving fire performances of PEAL: More second-life options for recycled Tetra Pak®
Full text linkThe purpose of this work was to evaluate and improve the flammability and combustion behavior of the polyethylene-based material obtained from the recycling of Tetra Pak® (PEAL) to widen its use to applications where these properties are required. Firstly, its thermal stability was investigated with thermogravimetric analysis, resulting in an enhancement in the main degradation step temperature (from 385◦C to 421◦C) due to the presence of the aluminum-flakes. Then, to improve the poor flammability (HB in UL-94 test) and combustion behavior (Fire Performance Index of 0.07) of the raw material, two flame retardant approaches were tested: an intumescent system made of ammonium polyphosphate and pentaerythritol, and magnesium hydroxide. In addition, the effectiveness of polyethylene as a charring agent was evaluated. Characterization was made with UL-94, cone calorimeter, and morphologic analysis. For all the materials tested, the temperature of the main weight loss step increased and the flammability rating improved (V2 for intumescent and V0 for magnesium hydroxide reached). Moreover, fire hazard decreased (Fire Performance Index of 0.15 and 0.55; Flame Retardancy Index of 2.6 and 10.0). Referring to the morphology, full compatibility was found in the PEAL–magnesium hydroxide compound, while PEAL-intumescent appeared as a heterogeneous system
Effects of sterically hindered N-alkoxyamines on photo-oxidative stability of reinforced polypropylene
No full textThe influence of sterically hindered N-alkoxyamine (such as Flamestab®NOR116) on the photo-oxidative stability of calcium carbonate reinforced polypropylene (CCPP) used for production of plastic collars has been investigated. The samples, prepared by melt compounding, were exposed to artificial accelerated photo-ageing carried out at »>300 nm and 45 oC in air. The aged samples were investigated by FT-IR and UV-visible spectroscopies. The results showed that the presence of Flamestab®NOR116 into CCPP induced a remarkable change of the kinetic of photo-oxidation such as a significant increase of oxidation induction time and reduction of oxidation rat
Fully bio-based ternary polymer blends: structural characterization and mechanical behavior
No full textIn this work, ternary immiscible blends based on poly (lactic acid) (PLA) as major phase and polybutylene succinate (PBS) and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHH) as minor phases were prepared through melt blending, aiming at obtaining fully biobased materials with enhanced ductility and toughness as compared to the inherently brittle matrix. Thermodynamic considerations based on the calculation of the interfacial tensions predicted the achievement of a partial encapsulation between the domains of the two minor components embedded in the PLA matrix. The rheological characterization revealed higher melt viscosity and elasticity for all the ternary blends as compared to the PLA matrix and a growing level of interfacial interactions between the different phases when increasing amounts of PBS are incorporated. This last was confirmed through morphological observations, which allowed demonstrating the achievement of an improved homogeneous microstructure for the blends containing 30 and 40 wt% of PBS, notwithstanding the relatively good interfacial adhesion obtained in all the explored materials. The combined effect of the strong established interfacial interactions and of the uniform morphology resulted in the obtainment of dramatic increments of ductility, tensile toughness and impact strength for all formulated ternary blends as compared to the PLA matrix, and especially for those containing 30 or 40 wt% of PBS, while maintaining satisfactory levels of stiffness and tensile strength
Layer-by-Layer nanostructured interphase produces mechanically strong and flame retardant bio-composites
No full textIn this manuscript, the Layer-by-Layer technique is used to modify the surface of flax fabrics using a quad-layer architecture (QL) prior to their assembly in polylactic acid biocomposites. The aim is to produce nanostructured interphases capable of conferring flame retardancy while maintaining mechanical properties. Only 2.5 QL significantly improve the flame retardancy and fire safety of the prepared composites as demonstrated by LOI values of 25.3%, considerably reduced flame spread rates and the substantial reduction in peak of heat release rate (−33%) and maximum average rate of heat emission (−30%) during cone calorimetry. Mechanical testing showed improved modulus and limited reductions in flexural strength. These results make the approach developed in this manuscript very attractive in the design of advanced biocomposites with optimized fire retardancy and mechanical properties
Rheology, Morphology and Thermal Properties of a PLA/PHB/Clay Blend Nanocomposite: The Influence of Process Parameters
Full text linkThe effect of process parameters on the final properties of a poly-lactic acid (PLA) and polyhydroxybutyrate (PHB) polymer blend filled with nanoclays was evaluated. To this aim, the nanofilled blend was processed in a co-rotating twin screw extruder, considering three different screw profiles and different values of the screw rotation speed, and the thermal and thermo-mechanical properties of the so-obtained materials were investigated. Furthermore, XRD analyses, SEM observations and rheological characterization were exploited to infer the coupled effect of the process parameters and nanoclay presence on the microstructure of the filled blend. Preliminary thermodynamic calculations allowed predicting the preferential localization of the nanoclay in the interfacial region between the polymeric phases. The relaxation mechanism of the particles of the dispersed phase in nanofilled blend processed, by rheological measurements, is not fully completed due to an interaction between polymer ad filler in the interfacial region with a consequent modification of the blend morphology and, specifically, a development of an enhanced microstructure. Therefore, by varying the screw configuration, particularly the presence of backflow and distribution elements in the screw profile, high shear stresses are induced during the processing able to allow a better interaction between polymers and clay. This finding also occurs in the thermo-mechanical properties of material, as an improvement of storage modulus up to 20% in filled blend processed with a specific screw profile. Otherwise, the microstructure of filled blend processed with different screw speed is similar, according to the other characterizations where no remarkable alterations of materials were detected
Is it possible to mechanical recycle the materials of the disposable filtering masks?
Full text linkIn a singular period, such as during a pandemic, the use of personal protective masks can become mandatory for all citizens in many places worldwide. The most used device is the disposable mask that, inevitably, generates a substantial waste flow to send to incineration or landfill. The article examines the most diffused type of disposable face mask and identifies the characteristic of the constituent materials through morphological, chemical, physical, and thermal analyses. Based on these investigations, a mechanical recycling protocol with different approaches is proposed. Advantages and disadvantages of the different recycling solutions are discussed with considerations on necessary separation processes and other treatments. The four solutions investigated lead to a recycling index from 78 to 91% of the starting disposable mask weight. The rheological, mechanical, and thermo-mechanical properties of the final materials obtained from the different recycling approaches are compared with each other and with solutions present on the market resulting in materials potentially industrially exploitable
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