N. R. Demarquette

• École de Technologie Supérieure

Material extrusion (MEX) 3D printing of highly filled polymer has demonstrated great capabilities for prototyping or rapid manufacturing of metallic parts exhibiting complex shapes. However, only a few studies have quantitatively examined the dimensional properties of simple shape printed parts and virtually none has investigated the correlation be...

The effectiveness of layered particles as processing aid agents in molten polystyrene was studied. Three graphene grades and two clays of different lateral size were selected for this purpose. The morphologies of the composites were observed using scanning electron microscopy. Steady shear measurements were carried out and the Carreau–Yasuda model...

Dielectric performance of post‐consumer recycled HDPE blended with virgin HDPE was investigated to evaluate the possibility of using these materials for the insulation of electrical wires and cables. The presence of organic and inorganic impurities was investigated using thermal and chemical methods (TGA, DSC, and EDX). The characterization of impu...

Conductive polymeric materials are commonly obtained by adding conductive nanoparticles to blends of immiscible polymers that form a cocontinuous morphology. However, during processing, morphology changes, affecting material properties. This study investigates the impact of steady shear deformation on the morphological and electrical properties of...

The surface energy of various mold materials for low-pressure powder injection molding was evaluated using values of contact angles (Owens–Wendt method), and correlated with the feedstock moldability and mold adhesion. The surface tension of the binder used to formulate a metallic-based feedstock was also measured in the molten state at a typical i...

This work demonstrates how the addition of few-layer graphene (FLG) influences the processability and mechanical properties of the mixed polyolefin waste stream (R-(PE/PP)). Three different types of compounds were investigated: (1) R-(PE/PP) with FLG; (2) blends of R-(PE/PP) with prime polyethylene (PE) or polypropylene (PP) or PP copolymer; and (3...

2D materials are a very up‐and‐coming class of additives in the field of polymer composites due to their versatility and exceptional intrinsic properties. This enables researchers to create a variety of nanocomposites that can be employed in a myriad of emerging multifunctional applications. The performance of such nanocomposites depends heavily on...

The surface energy of various mold materials for low-pressure powder injection molding was evaluated using values of contact angles (Owens-Wendt method), and correlated with the feedstock moldability and mold adhesion. The surface tension of the binder used to formulate a metallic-based feedstock was also measured in the molten state at a typical i...

In this work, a study of the linear viscoelastic properties of co-continuous polypropylene/polystyrene (PP/PS) blends filled with multi-wall carbon nanotubes (MWCNT) is presented. The YZZ rheological model [1] is employed to correlate the rheological behavior of the blends with their microstructure and electrical properties. A test design involving...

Graphene-based composites are promising candidates to improve properties in flexible packaging to protect electronic devices. However, the literature hardly addresses the industrial scale requirements. In this context, high-density polyethylene (HDPE), a common packaging material, and an industrial grade graphene (G) were used to prepare multilayer...

Electrospun fibers of the thermo-and pH sensitive poly(N-vinylcaprolactam-co-acrylic acid) (Poly(NVCL-co-AA) loaded with 10% and 30 wt% caffeine (Caf) were obtained by electrospinning and evaluated as potential drug delivery systems. Caffeine was used as a hydrophilic drug model, and poly(NVCL-co-AA) containing either 20 or 30 mol% AA was used as a...

In this study, poly(N-vinylcaprolactam-co-acrylic acid) (poly(NVCL-co-AA)) containing 20 and 30 mol% AA, were used to prepare thermo-and-pH-sensitive fibers containing a hydrophobic drug, ketoprofen, via electrospinning. Ketoprofen entrapment efficiency was assessed via UV–visible spectroscopy and revealed high values. The interaction drug/copolyme...

In this work, the effect of cellulose filaments (CFs) dispersion on the relaxation behavior of thermoplastics matrices was studied. The dispersion state of polystyrene/CF composites produced by two different processing methods, leading to two different dispersion qualities, was assessed using scanning electron microscopy (SEM), transmission electro...

The effect of the crystallization of polypropylene (PP) forming an immiscible polymer blend with polystyrene (PS) containing conductive multi-wall carbon nanotubes (MWCNTs) on its electrical conductivity and electrical percolation threshold (PT) was investigated in this work. PP/PS/MWCNTs composites with a co-continuous morphology and a concentrati...

There is great interest in the use of graphene and derivatives in the production of polymer nanocomposites as it provides improvements in the properties of the materials to which they are associated. Such improvements depend heavily on filler dispersion and the interaction between the nanomaterials and the matrix. This work aimed to study the compa...

In this work, the effect of different solvents and solvent binary mixtures on the morphology of electrospun pullulan (Pull) nanofibers was evaluated. The solution viscosities, interactions between solvent and polymer, as well as, solvent vapor pressure, were correlated to the morphology and diameters of the nanofibers. Water, dimethylformamide (DMF...

In this work, 32 different feedstocks formulated from four different stainless steel powders and two wax-based binder systems (paraffin wax and beeswax), for which the proportion of two different surfactant agents was varied from 0 to 5 vol.% (stearic acid and oleic acid), were obtained. The viscosity of the feedstocks according to the shear rate w...

Series of clay‐containing nanocomposites have been prepared and investigated using frequency‐domain dielectric spectroscopy at different temperatures. Different matrix materials have been used: neat low‐density polyethylene (LDPE) with and without compatibilizer and co‐continuous blends of LDPE with two grades of polystyrene‐b‐poly(ethylene‐co‐buty...

In this study, the dynamic viscoelastic moduli and electrical conductivity of blends of linear low density polyethylene (LLDPE) and ethyl vinyl acetate (EVA) presenting a co-continuous morphology, filled with commercial graphene (GN) nanoplatelets, have been assessed as function of thermal annealing time and correlated with changes in the morpholog...

The addition of six different clays (laponite, montmorillonite, halloysite, and their organomodified counterparts) to poly(methyl methacrylate), polystyrene, and their blends was studied. The morphologies of the obtained composites were studied using transmission electron microscopy and scanning electron microscopy. Small angle oscillatory shear ex...

In this work, cocontinuous blends of linear low density polyethylene/ethyl vinyl acetate containing graphene (GN) have been studied. Although mass-produced GN grade prepared by mechanochemical exfoliation of graphite and a facile melt compounding technique were adopted, it was possible to lower the electrical percolation threshold significantly by...

This paper investigates the effects of organomodified montmorillonite (clay) and styrene-(ethylene-co-butylene)-styrene triblock copolymer (SEBS) on the morphological and electrical properties of polypropylene (PP). A series of binary PP-clay nanocomposites along with nanocomposites having a blend matrix were prepared. The nanofillers were found to...

In this work, nanofiber scaffolds for surface drug delivery applications were obtained by electrospinning poly(N‐vinylcaprolactam) (PNVCL) and its blends with poly(ε‐caprolactone) and poly(N‐vinylcaprolactam)‐b‐poly(ε‐caprolactone). The process parameters to obtain smooth and beadless PNVCL fibers were optimized. The average fibers diameter was les...

Electrospinning of nonsolvent‐induced phase‐separated ternary (NIPST) systems has gained a lot of interest due to its potential to produce (nano)fibers, which are superficially and internally porous with nanoscale surface roughness. Membranes produced from such systems are expected to have a high specific surface area (SSA; e.g., more than 50 m2 g−...

This paper discusses the charge transport and accumulation in clay-containing LDPE (low density polyethylene) nanocomposites. LDPE is shown to host charges of both polarities in the form of homo and heterocharge when subjected to high electric fields. The addition of nanoclays has been shown to always increase the high field DC conductivity of the...

Economically viable high‐density polyethylene (HDPE)/graphene nanocomposites were produced using mass produced graphene powder and an industrial twin‐screw melt‐compounding machine. Rheological and electrical properties were investigated and scanning electron microscopy was carried out to investigate graphene dispersion and its network formation in...

Electrospun mats have many possible applications in which it is important to control their interaction with water: when used as separation membranes, superhydrophobic mats can remove oil from water, whereas when used as scaffolds for tissue engineering, hydrophilic mats present better cell affinity. Frequently, however, the surface properties of th...

Electrospinning of ternary systems containing a nonsolvent is of interest because it can produce fibers that are highly porous on the surface and in the core. Despite the growing interest and applications, electrospinning of such ternary systems is challenging due to their evolving viscoelastic properties prior to electrospinning. In this study, we...

Polymers can be reinforced by layered silicate fillers leading to polymeric nanocomposites with altered dielectric properties, often superior breakdown and endurance strength than those of neat polymers can be observed. In addition, mitigation of space charge accumulation can potentially be reached with such nanocomposites, for several reasons such...

Nanocomposites based on poly(styrene‐b‐ethylene‐ran‐butylene‐b‐styrene) (SEBS) and carbon nanotubes (CNT) (SEBS/CNT), as well as SEBS grafted with maleic anhydride (SEBS‐MA)/CNT were successfully prepared for electromagnetic shielding applications. Both SEBS/CNT and SEBS‐MA/CNT nanocomposites were prepared by melt compounding and post‐processed usi...

The compatibilization mechanism of poly(methylmethacrylate) (PMMA)/polystyrene (PS) blends induced by PMMA-b-PS block copolymers of different molar masses (30 and 104 kg/mol) was studied. The blend morphologies with and without copolymers were observed by scanning electron microscopy. The rheological behavior was studied performing small amplitude...

Accepted In this study, the mechanical strength and the AC short term breakdown strength of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) thermoplastic elastomer clay-containing nanocomposites have been investigated as function of their morphologies. The SEBS/clay nanocomposites with tailored morphologies were prepared previously b...

Blends of polyethylene (PE) with nanocomposites of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene grafted maleic anhydride (SEBS-MA) thermoplastic elastomer filled with Zinc Oxide (ZnO) nanoparticles have been studied as potential candidates for applications in HV insulation systems including HVDC cables. In particular, the dielectric and m...

Microstructure and electrical breakdown properties of blends and nanocomposites based on low-density polyethylene (LDPE) have been discussed. A series of LDPE nanocomposites containing different amount of organomodified montmorillonite (clay) with and without compatibilizer have been prepared by means of melt compounding. Two sets of blends of LDPE...

Moldability and segregation of feedstock are linked to the rheological behavior of the powder-binder mixture. In this study, the impact of binders on viscosity and segregation of feedstocks was investigated. The experiments were conducted on several feedstocks obtained by mixing Inconel 718 powder with paraffin wax-based binder systems. The viscosi...

The rheological behavior of wax-based feedstocks has a direct impact on successful mold filling for parts produced by low-pressure powder injection molding. During a rheological test, segregation may occur within low-viscosity feedstocks, leading to errors in results, and to an improper evaluation of the flowability of powder-binder mixtures. The s...

Thermoplastic elastomer nanocomposites based on respectively polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) and polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene grafted maleic anhydride (SEBS-MA) block copolymers and containing functionalized zinc oxide (ZnO) nanoparticles have been investigated as candidate materials for high...

Composites of low-density polyethylene (LDPE) containing 1 wt% and 5 wt% polyhedral oligomeric silsesquioxanes (POSS) of different substituents (methyl, isobutyl, isooctyl) were obtained by extrusion. The composites' potential application in high-voltage (HV) power cable insulation was investigated by broadband dielectric spectroscopy, progressive-...

In this study, porous micron-sized fibers of polylactic acid (PLA) are fabricated via electrospinning of PLA-dichloromethane (DCM)-hexane systems with no post treatment involved. Several compositions from the liquid-liquid phase separated region of the phase diagram of this ternary system are selected and their electrospinnability are investigated...

The dielectric properties of nanocomposites of polystyrene-b-poly (ethylene-co-butylene)-b-polystyrene (SEBS) triblock copolymers containing organically modified clay nanoparticles featuring controlled spatial orientation at the nanoscale: isotropic, totally oriented and partially oriented, have been investigated and correlated with the nanocomposi...

Polymer blending can be used as a one-step surface modification technique to alter the wettability of electrospun mats. In this work, blends of hydrophobic thermoplastic elastomer SEBS with hydrophilic PEO or amphiphilic PEO-PPO-PEO were prepared and the resulting surface properties investigated. The low surface energy PPO block drove the segregati...

Hybrid nanocomposites of poly (styrene-b-ethylene-ran-butylene-b-styrene) (SEBS), graphene nanoplatelets (GnP), and carbon nanotubes (CNT) were successfully prepared by melt compounding for electromagnetic shielding applications. The morphologies of the carbon nanoadditives and nanocomposites were investigated by Raman spectroscopy, field emission...

Colloque annuel sur les polymères avancés et la rhéologie

Although electrospinning is an established technique, it was not until the 1980s that it attracted the attention of the scientific community with the advent of nanotechnology. This technique has been shown to be useful for preparing porous membranes formed of PVDF fibers. PVDF is of particular interest, because its crystalline β-phase has good piez...

Low density polyethylene/polyhedral oligomeric silsesquioxanes (LDPE/POSS) composites were fabricated by melt blending with a twin-screw extruder under a rotation speed of 200 rpm and barrel zone temperatures of 115–130 °C. Two types of POSS were investigated: octamethyl POSS (OmPOSS) and isooctyl POSS (IoPOSS).Microscopic features of the samples w...

to be attached

The impact of binders and temperature on the rheological properties of feedstocks used in low-pressure powder injection molding was investigated. Experiments were conducted on different feedstock formulations obtained by mixing Inconel 718 powder with wax-based binder systems. The shear rate sensitivity index and the activation energy were used to...

The dielectric performance of nanocomposites made of Polyethylene (PE) and a master batch of Styrene- Ethylene/Butylene-Styrene grafted maleic anhydride (SEBS-MA) triblock copolymer containing individually dispersed zinc oxide (ZnO) nanoparticles, was investigated in comparison with conventional PE/ZnO nanocomposites and correlated to the differenc...

Various methods were attempted to fabricate polyethylene/octaisobutyl polyhedral oligomeric silsesquioxanes (PE/OibPOSS) composites. Microscopic features of the samples were observed to evaluate the effectiveness of these methods in producing nanodielectrics. Furthermore, the samples were subjected to progressive-stress breakdown tests and erosion...

In this work, poly (styrene-b-ethylene-ran-butylene-b-styrene) and carbon nanotube (SEBS/CNT) nanocomposites were prepared by melt compounding for electromagnetic shielding applications. The structural characteristics and the morphology of carbon nanotubes (CNT) and nanocomposites were investigated using Raman spectroscopy and Field Emission Gun Sc...

The interaction of electrospun mats with water is critical for many possible applications, and the water contact angle on the surface is the parameter usually measured to characterize wetting. Although useful for hydrophobic surfaces, this approach is limited for hydrophilic mats, where wicking has also to be considered. In this case, it is still u...

In this work, the effect of extensional flow on the morphology of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) triblock copolymers and their clay-containing nanocomposites was evaluated. Four types of SEBS copolymers with different block compositions and cylindrical morphology were chosen to understand the effects of cylinder orien...

officially accepted for publication Xylene solution blending was tested as a method for producing low-density polyethylene (LDPE)-based nanodielectrics containing 1 wt% and 5 wt% polyhedral oligomeric silsesquioxanes (POS) of different types—octamethyl POS, octaisobutyl POS, and isooctyl POS. The chemical composition, the morphology, the thermal p...

Melt blending with a twin-screw extruder was tested as a method for producing polyethylene (PE)-based nanodielectrics containing octaisobutyl polyhedral oligomeric silsesquioxanes (OibPOSS). An extrusion temperature profile with comparatively low barrel zone temperatures (110 oC–130 oC) was employed and two rotation speeds (50 and 200 rpm) were inv...

In this study, the rheological and dielectric properties of two sets of nanocomposites prepared respectively from Styrene-Ethylene-Butylene-Styrene (SEBS) and SEBS grafted maleic anhydride (SEBS-g-MA) block copolymer matrices and surface functionalized zinc oxide nanoparticles have been investigated. The interaction at the polymer-nanoparticle inte...

Poly(3-hydroxybutyrate)(PHB), a natural polymer produced by bacteria via crop-based manufacturing, presents interesting characteristics like thermoplastic behaviour and biodegradability. However, its peculiar fine lamellar structure is highly susceptible to an intrinsic ageing phenomenon that contributes to a remarkable brittleness and low toughnes...

In this work, the effect of controlling the morphology on the dielectric properties of triblock copolymers and their clay-containing nanocomposites was evaluated. Two different copolymers: polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) and SEBS grafted with maleic anhydride were used for that purpose. Morphologies with different degr...

High-energy ball milling was tested as a method for producing Ultra High Molecular Weight Polyethylene (UHMWPE)- based nanodielectrics containing 1 wt% and 5 wt% OctaIsoButylPOSS (OibPOSS). Qualitative and quantitative evaluations were used to explore the compatibility between OibPOSS and PE. Several ball milling variables were optimized in a bid t...

Thermoplastic elastomer SEBS, a triblock copolymer composed of styrene (S) and ethylene-co-butylene (EB) blocks, can be dissolved and processed by electrospinning to produce flexible non-woven mats that can be interesting for applications like filtration or separation membranes. Controlling surface properties such as hydrophobicity/hydrophilicity i...

In this work, a polymer blend of High Density Polyethylene HDPE and Styrene-Ethylene-Butylene-Styrene SEBS triblock copolymer has been prepared. The composition of the blend was tailored to control the morphology from a state of dispersed droplets of SEBS in a PE matrix to a fiber-like morphology. The microstructure of the blends has been assessed...

Nanodielectrics have attracted the attention of many scientists and industrials as they may present superior dielectric properties compared to conventional dielectrics. Polyhedral Oligomeric SilSesquioxanes (POSS) is a type of filler of great interest in the field of nanodielectrics. In this work, xylene solution blending was used to produce Low De...

In this work, the effect of the incorporation of a sodium smectite clay (Brasgel) in Nylon-6 toughened with Poly (vinyl butyral) film (PVB film) was evaluated. The composites contain 60 wt.% of Nylon-6, 40 wt.% of PVB film and 5 wt.% of clay, relative to the total weight of the mixture. The clay was previously purified by sedimentation, and dried i...

Poly(3-hydroxybutyrate) (PHB) undergoes an ageing process that contributes to its remarkable fragility. Blending it with an elastomer is a possibility to increase toughness. In this work, the mechanical properties of a 70/30 wt% blend of PHB and poly(ethylene-co-methyl-acrylate-co-glycidyl-methacrylate) were studied over time. The phenomenon of age...

Nanodielectrics have attracted the attention of many scientists and industrials as they may present superior dielectric properties compared to conventional dielectric composites. However, the success of these materials relies on a proper dispersion of the nanofiller within the matrix. In this work, the efficacy of hexane slurry blending in obtainin...

In this paper, intercalated vs. exfoliated structures of clay-containing nanocomposites of polystyrene-b-poly (ethylene-co-butylene)-b-polystyrene are studied. The morphology of the nanocomposites, characterized earlier by microscopy and Small Angle X-Ray Scattering, is confirmed through the study of the thermal, mechanical, rheological and dielect...

Clay-containing nanocomposites of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) copolymers having cylindrical domains were obtained by melt extrusion using a tape die. One type of sample (SEBS-MA) had maleic anhydride attached to the middle block. Two types of organoclays were added, namely Cloisite 20A and Cloisite 30B. Small angle...

Block copolymer nanocomposites are materials with interesting structures and properties. The control of their morphology can be obtained during processing, and anisotropic structures may be oriented in one or two directions, affecting both the copolymer domains and nanoparticle alignments. In this work mono- and bioriented films of SEBS copolymer a...

This work presents a systematic study about thermoplastic starches. Corn starch was mixed with 2 and 4 wt.% of carboxylic acid and 20 to 30 wt.% of water. The samples were prepared in an internal mixer coupled to a torque rheometer, and the torque values were monitored during mixing. The specimens for mechanical tests were calendered and cut with a...

In this work, the effect of blend composition and previous photodegradation on the biodegradation of polypropylene/poly(3-hydroxybutyrate) (PP/PHB) blends was studied. The individual polymers and blends with or without the addition of poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) [P(E-MA-GMA)] as a compatibilizer (in the case of 80/20...

For the last decade, there has been lots of interest in the development of nanodielectrics as these materials may present superior dielectric properties when compared to traditional composites. However, the success of these materials relies on a proper dispersion of nanofillers within the matrix. In this work, UHMWPE/POSS composite of Ultra-High-Mo...

In this work, the morphology and linear viscoelastic behavior of PMMA/PP blends to which a graft copolymer PP-g-PMMA has been added was studied. The copolymer concentration varied from 1 to 10 wt % relative to the dispersed phase concentration. The rheological data were used to infer the interfacial tension between the blended components. It was ob...

The incorporation of polyhedral oligomeric silsesquioxane (POSS) into polymeric materials may result in great improvements of polymer properties including electrical dielectric properties. However, the success of achieving such a material with improved properties relies on a proper dispersion and distribution of POSS within the polymer. In this pap...

Due to their structural and morphological characteristics block copolymers can present interesting mechanical properties, which can be improved by the addition of clay. Furthermore, their morphology can be aligned during processing allowing the achievement of highly anisotropic materials. In this work, the mechanical properties of SEBS block copoly...

A new method to characterize the long-time linear relaxation mechanisms of immiscible blends based on creep experiment was developed. Small-amplitude oscillatory shear and incomplete creep/recovery experiments were combined to characterize immiscible blends of polypropylene with dispersed droplets of polystyrene. An experimental protocol was define...

In this work, a commercial Brazilian clay (BUN Bentonit União Nordeste), was purified by three different processes. Impurities and iron oxides limit the use of the Brazilian clays in applications such as filler for nanocomposites. The first purification method refers to the separation of the colloidal fraction of the clay, to remove the remaining l...

Blending polypropylene (PP) with biode-gradable poly(3-hydroxybutyrate) (PHB) can be a nice alternative to minimize the disposal problem of PP and the intrinsic brittleness that restricts PHB applications. However, to achieve acceptable engineering properties, the blend needs to be compatibilized because of the immiscibility between PP and PHB. In...

In this work poly(hydroxybutyrate/poly(vinyl butyral)- co-(vinyl alcohol)-co(vinyl acetate) (or ethylene propylene diene monomer rubber) blends were prepared by conventional processing techniques (extrusion and injection moulding). A droplet type morphology was obtained for P(3HB)/PVB blends whereas P(3HB)/EPDM blends presented some extent of co-co...

The influence from the type of polypropylene on the photodegradation resistance of blends of polypropylene/high impact polystyrene(PP/HIPS) was studied. A virgin polypropylene(PPv) and another sample that suffered prior thermo-mechanical degradation(PPrep) were used. All materials, components of the blends and blends were exposed to UVradiation for...

Composites of polystyrene/montmorillonite (PS/MMT) containing 2.5wt. (%) clay were prepared with two types of clays modified with quaternary ammonium salts.Were also prepared samples of PS+quaternary ammonium salt, using the same amount employed in modifying the clay.All samples were exposed to UV radiation for up to 12 weeks, and then tests were c...

Block copolymers are materials with many applications in the field of thermoplastic elastomers. Their properties can be further improved by the addition of nanoclays. However, the morphological and rheological properties of these hybrid materials are not very well known. In this work, the effects of clay concentration on the evolution of morphology...

The influence of the addition of high-impact polystyrene (HIPS) on polypropylene (PP) photodegradation was studied with blends obtained by extrusion with and without styrene–butadiene–styrene (SBS) copolymer (10 wt % with respect to the dispersed phase). The concentrations of HIPS ranged from 10 to 30 wt %. The blends and pure materials were expose...

Hybrid latices of poly(styrene-co-butyl acrylate) were synthesized via in situ miniemulsion polymerization in the presence of 3 and 6 wt % organically modified montmorillonite (OMMT). Three different ammonium salts: cetyl trimethyl ammonium chloride (CTAC), alkyl dimethyl benzyl ammonium chloride (Dodigen), and distearyl dimethyl ammonium chloride...

The effect of ultraviolet radiation on the properties of poly(3-hydroxybutyrate) (PHB) was studied. The PHB investigated is produced from microbial fermentation using saccharose from sugarcane as the carbon source to the bacteria. The material was exposed to artificial UV-A radiation for 3, 6, 9 and 12 weeks. The photodegradation effect was followe...