Pierre G. Lafleur

• Eng., Ph.D.
• VP Academic and International at Polytechnique Montréal

In this work, graphene oxide has been synthesized and functionalized with a silane agent to improve the interactions with nylon 6,6. The functionalization reactions for graphene oxide (GO) resulted in a different way as expected, a heteroatom was grafted into graphene hexagonal network, which led to a new route of chemical modification of graphene...

Blends of poly(L-lactic acid)/nanoparticle silver and GTA (plasticizer) are present, and the crystallization effect was studied. The effect of the crystallization was investigated by oxygen permeability, isothermal crystallization, and mechanical behavior. Observed properties varied according to the concentration of Ag-NP (0.025–0.1%) dispersed in...

A study of the improvement of the mechanical and thermal properties of nanocomposites prepared with polypropylene (PP) and different graphene samples [graphene oxide (GO), reduced GO (RGO), and commercial graphene (G)] is presented. X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy characterization were applied to the graphene samples. T...

Previous studies of Candelilla bagasse fiber (CBF) have demonstrated the improvement of fiber-polymer adhesion; in the present investigation, the CBF was used to reinforce fiber of Polypropylene composites varying the amount of fiber (0, 20 and 30 wt%), using Maleic anhydride as compatibilizer. The total wax of cuticle/intercuticular varies between...

Polyethylene–montmorillonite nanocomposites were prepared in the melt applying various ultrasonic powers (231, 347, and 462 W) and temperatures (185, 200, and 215 °C) in the presence of itaconic acid. Dispersion–exfoliation of montmorillonite and in situ low density polyethylene functionalization with itaconic acid were carried out by ultrasound as...

In this study, the combination of organomodified montmorillonite (MMT), magnesium hydroxide (MDH), graphene oxide (GO) and expandable graphite (EG) as intumescent flame retardant for Linear Low-Density Polyethylene-Cyclo-Olefin Copolymer (LLDPE/COC) blends has been investigated. An amine-alcohol modified polyethylene (PEgDMAE) was used as compatibi...

Monodispersed silver nanoparticles (Ag-NPs) were synthesized by chemical reduction in aqueous medium and transferred in chloroform to be redispersed in the plasticized matrix of poly(L-lactic acid) (PLA) by melt compounding. PLA nanocomposites were prepared using a combination of Ag-NPs in amounts of 0.01, 0.025, 0.05, 0.075 and 0.1% in weight, wit...

Plastic deformation of polylactide has been known as a self-reinforcement alternative to improve mechanical and barrier properties. In this study, the structural evolution was investigated during a hot-drawing process, at different initial strain rates and temperatures above Tg of polylactide. The drawing process at Tg +10 °C, led to the formation...

The effect of acrylic acid (AA) and amine alcohol (DMAE) functionalization via plasma of carbon nanofibers (CNF) on physical and mechanical properties of polypropylene-CNF nanocomposites prepared by melt mixing was studied. The behavior of these functionalized CNF via plasma was compared with a CNF functionalized by oxidation with a mixture of sulp...

The effect of acrylic acid (AA) and amine alcohol (DMAE) functionalization via plasma of carbon nanofibers (CNF) on physical and mechanical properties of polypropylene-CNF nanocomposites prepared by melt mixing was studied. The behavior of these functionalized CNF via plasma was compared with a CNF functionalized by oxidation with a mixture of sulp...

Processing poly(lactic acid) with low concentrations of silver using a twin-screw extruder leads to nanocomposites with enhanced crystallinity and improved mechanical properties

Poly (L-lactic acid) nanocomposites based on silver nanoparticles (PLA/AgNP) were prepared by melt blending using a twin screw extruder (TSE). Nanocomposites at low concentrations were prepared with 0.1, 0.2 and 0.3wt% of AgNP to enhance the crystallinity and improve the thermal and mechanical properties of PLA. AgNP’s smaller than 100 nm which inc...

Melt compounding of polylactide with ductile polymers is widely proposed as an efficient alternative to overcome its inherent brittleness. An ethylene alkyl acrylate is used as toughening modifier of polylactide. A two-phase morphology is detected by melt blending of Polylactide and Biomax Strong. Furthermore, the effect of the addition of organica...

Graphene oxide (GO) derived from oxidation of natural graphite contains many active groups that can interact with a great variety of polar moieties. In this work, polypropylene (PP)/graphene oxide nanocomposites using polypropylene (PP) grafted with amine-alcohol (PPgDMAE) as compatibilizer were prepared by two different methods. Maleic anhydride g...

The mechanical properties of polypropylene-bentonite nanocomposites were studied in this work. In this study, stearic acid was used as both a new surface modifier of the nano bentonite and a new interface modifier during the compounding of the nanocomposites with a twin-screw extruder. Three different weight concentrations (1.5 wt.%, 2.5 wt.%, and...

Las propiedades mecánicas de nanocompuestos de polipropileno (PP) con carbonato de calcio (CaCO3) fueron estudiados en este trabajo. Se utilizó ácido esteárico como un nuevo modificador de interfaz durante la preparación de los nanocompuestos utilizando una extrusora de doble husillo. La concentración en peso del nanorelleno (CaCO3) en los compuest...

Abstract Candelilla bagasse fiber (CBF) was prepared by a mesh sieve and ball-milling process and its reinforcing effect in a polymer matrix analyzed. Composites of polypropylene (PP) and CBF were prepared by melt blending with varying amounts (20,25, and 30 wt%) of fiber using maleic anhydride PP as coupling agent. The chemical composition of CBF wa...

A comparative study of the mechanical performance of PP and PP/PP-g-MAH blends reinforced with carbon fibre (CF) obtained by two different moulding techniques is presented. Three filler contents were used for fabricating the composites: 1, 3, and 5 pph (parts per hundred). The crystallisation behaviour of the composites was studied by differential...

Chain architecture is an influential parameter in melt processing of polymeric material. In this study effect of different chain structures on polylactide (PLA) film blowing process and on the final film properties was investigated. Blends of linear PLA with three branched poly(L-lactide)s with 4-arms star shaped, comb like and hyper branched struc...

In this research, the change in shape from spheres into triangular prisms by irradiation with sodium lamp were investigated to reinforce the PLLA matrix. Characterization of silver nanospheres (NE´s) and nanoprisms (NPr´s) were measured using UV-vis spectrometry, Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS) and Elemental analy...

This study was aimed at improving the process rheology of polylactide (PLA) melts by means of two strategies. First, PLAs of different branched structures, i.e., star shaped, comblike, and hyper branched, were synthesized and blended with a linear grade analog. Shear and extensional flow rheometry tests were performed on pure materials and their bl...

Star-shaped and comb-like poly(L-Lactide)s (PLA) are produced by employing multifunctional initiators, and hyperbranched structure is prepared using a cyclic co-monomer with hydroxyl group. FTIR, size exclusion chromatography, and H-NMR techniques are employed to characterize the synthesized polymers, validating the formation of desired structures...

The effects of the addition of organically modified nanoparticles on molecular dynamics, and subsequently, crystallization parameters were investigated using temperature modulated differential scanning calorimetry, dynamic mechanical analysis, and rheological measurements. Cold crystallization was observed to occur, at higher temperatures compared...

In this study, we present a study of polypropylene/bentonite composites where stearic acid was used as both a surface and interface modifier during the compounding of composites. The concentration of bentonite was 1.5, 2.5, 5.0, and 10 parts per hundred. The composites were characterized by impact resistance and tensile tests, rheological analysis,...

Effect of chain architecture on homocrystallization and stereocomplex formation behaviour of polylactide (PLA) in quiescent conditions was investigated by means of differential scanning calorimetry (DSC) and optical microscopy. Non-isothermal and isothermal crystallization of star shaped, comb like and hyper branched poly(L-lactides) (PLLAs) with s...

Las propiedades mecánicas de nanocompuestos de polipropileno (PP) con carbonato de calcio (CaCO3) fueron estudiados en este trabajo. Se utilizó ácido esteárico como un nuevo modificador de interfaz durante la preparación de los nanocompuestos utilizando una extrusora de doble husillo. La concentración en peso del nanorelleno (CaCO3) en los compuest...

We derive first a formula for the overall heat conductivity for dispersions of cuboid nanowires and recall similar formulas derived previously in [Behrang \textit{et al., Applied Physics Letters}, 2014, \textbf{104}, 233111 , \textbf{104}, 063106 and Behrang \textit{et al., Journal of Applied Physics},\textbf{114}, 014305 ], by using the same metho...

Polypropylene nanocomposite materials were prepared with 5 and 10 wt % cloisite C20A clay, jointly with 0.6 and 1.2 wt % of maleic anhydride (MA) for the simultaneous polymer functionalization and clay dispersion in a twin screw extruder assisted with ultrasonic irradiation, using different sonication intensities (231, 347, and 462 W, which corresp...

The synergistic effect of organo-modified montmorillonite (Nanomer I28E and Cloisite 20A) and metal hydroxides (magnesium hydroxide MH and alumina trihydrate ATH) as flame retardants in LDPE/EVA nanocomposites compatibilized with amino alcohol grafted polyethylene (PEgDMAE) was studied. Morphological characterization of nanocomposites was carried o...

Heat conductivity of dispersions can be modified by varying shapes of dispersed particles and also by making hybrid dispersions containing particles of different shapes and sizes. Spheres and their agglomerates that we have investigated previously are replaced in this paper by spheres and wires. The method used to derive the formulas for the overal...

This chapter aims to analyze, understand and model the single-screw extrusion process using semi-analytical tools, in order to improve the screw design or, quite simply, to improve the processing conditions. In general, a screw is divided into four distinct, yet interconnected, sections. These four sections, in order, are: solids conveying zone, me...

The twin-screw extrusion process is a very interesting process, which, due to its high versatility, can deal with a variety of challenges to develop increasingly complex materials. This chapter begins by providing some basic information about twin-screw extrusion. In particular, it briefly analyses the co-rotating extruders in detail, which are cur...

Flexible packaging has been used since the beginning of mankind. The main qualities to consider when developing flexible packaging are mechanical strength, adhesion, shine, transparency, impermeability, food compatibility and resistance to ageing. This chapter focuses on two main techniques, namely cast film extrusion and film blowing, to produce f...

Profile-shaped products manufactured by extrusion are grouped into the two main categories: (i) complex profiles that are intended for applications in construction and automotive industries; (ii) tubular products that include tubes and pipes. This chapter studies both types of products, by reviewing the problems encountered and the theoretical appr...

This chapter provides the basics of the methods used to calculate the polymer melt flows in extruders and extrusion dies. The main flow parameters can be calculated by solving the set of equations consisting of: conservation of mass; conservation of momentum; conservation of energy; and a constitutive equation. Although three-dimensional (3D) model...

This chapter provides the basics of continuum mechanics, rheology and heat transfer. It establishes the basic equations in continuum mechanics: the continuity equation and the equilibrium equation that will be used to solve a flow problem. In fact, in the majority of flows encountered in extrusion, it is the viscous characteristic that will predomi...

Some of the main applications of the extrusion process include metal wire coating and cable insulation. Wire coating and cable insulation are used in the production of telephone, electrical and submarine communication cables, etc. The elements of a wire coating line and those of cable insulation differ slightly: the feeding and winding coils must a...

We derive a formula for the heat conductivity coefficient of dispersions of wires in a homogeneous matrix. Such formula is particularly useful for thermoelectric applications. The method used to derive this type of formula in Behrang et al. [J. Appl. Phys. 114, 014305 (2013)] for spherical particles is adapted to generally oriented wires of a finit...

The effects of stearic acid treatment on the crystallization, morphology, thermal, and mechanical properties of polypropylene (PP)/montmorillonite (Mm) nanocomposites were investigated. Stearic acid was used as a new surface modifier for Mm, and also small amounts of this acid were used as a new interface modifier. Nanocomposites containing 1.5, 2....

The rubberlike behavior of thermoplastic vulcanizates (TPVs), based on polypropylene/ethylene propylene diene M-class rubber (PP/EPDM), and their corresponding nanocomposites was investigated. The temperature Scanning Stress Relaxation (TSSR) method was used. Polypropylene nanocomposites, with different nanoclay dispersion levels, ranging from inte...

In this work, we investigated the effect of four different configurations at the exit of a single‐screw extruder on the induction of beta phase in PP for four different rotational speeds. The configuration of a breaker plate with 120 orifices of 1‐mm diameter and 7‐mm length each, give the highest content of beta‐phase (56.92%), for a screw rotatio...

A combination of the effective medium and the phonon approaches is used to investigate heat conduction in heterogeneous media composed of a homogeneous matrix in which spherical particles of micro and nanosizes are dispersed. In particular, we explore the effect of different types of scattering on the particle-matrix interface, temperature dependen...

The β-phase in polypropylene (PP) induced by shear rate in a single-screw extruder was studied. PP samples were extruded with and without a breaker plate at the exit of the extruder at five different screw rotational speeds: 20, 40, 60, 80, and 100 rpm. Differential scanning calorimeter was used to observe the melting behavior of the samples. The β...

The study considers the effects of different dispersion levels of nanoclay on the crosslinking reaction of thermoplastic vulcanizate (TPV) nanocomposites based on polypropylene/ethylene propylene diene M-class rubber (PP/EPDM). PP nanocomposites with dispersion level ranging from intercalated structures to a mixture of intercalated tactoids and exf...

In this paper, a study on Polypropylene (PP)/bentonite composites is presented. PP/bentonite composites were prepared using 5%, 10% and 25% of concentration in weight of unmodified and modified bentonite filler. The relative leve! of the beta phase of the samples was calculated using Wide Angle X-ray Diffraction (WAXD). Differential scanning calori...

Incorporation of clay in polymers is known to improve mechanical properties such as tensile modulus and tensile strength, but to generally decrease elongation at break and toughness. However, recent studies reported an increase in elongation at break for linear low density polyethylene based nanocomposites. In this work, the tensile properties of c...

This work is aimed at determining the effect of nanoclay and polyepichlorohydrin-co-ethylene oxide (ECO) content on the microstructure and mechanical properties of PA6/ECO thermoplastic elastomers (TPEs). TPE nanocomposites were prepared in a laboratory mixer using polyamide 6 (PA6), ECO, and an organoclay by a two-step melt mixing process. First,...

Ultrafine aluminum powders have been identified as very promising fuels as part of energetic materials formulations. However, the large specific surface area that gives these powders a high reactivity also makes them particularly difficult to maintain in an unoxidized state. They also agglomerate easily during compounding processes. The coating of...

A wide range of PE materials, including LLDPE, HDPEs and LDPE were used for preparation of the blown films. By changing processing conditions, different structures for these blown films were produced and their structural parameters investigated. Establishing fundamental /structural model between structural parameters and tensile modulus of blown fi...

The effects of different polypropylene (PP)-g-maleic anhydride polymers, used as compatibilizers, on the degree of exfoliation and co-continuity of PP/ethylene-propylene-diene terpolymer (EPDM) thermoplastic elastomer (TPE)/clay nanocomposites were investigated. X-ray diffraction and transmission electron microscopic micrographs showed that nanocom...

Steady and transient nonlinear melt-state viscoelastic properties of poly[(butylene succinate)-co-adipate] (PBSA), a biodegradable polyester, are investigated. Experimental data are compared with predictions of a rheological model developed by Ait-Kadi et al. (J Rheol, 1999, 43, 51–72). The results show that the model predicts very well the steady...

Polyethylene/montmorillonite nanocomposites based on LDPE, HDPE and LLDPE of similar rheological properties were prepared and mechanically tested in tension mode. It was shown that nanocomposites based on LLDPE exhibit a very peculiar behavior, with a significant improvement in toughness (elongation at break). The microstructural features of the va...

Transient elongational rheology of two commercial-grade polypropylene (PP) and the organoclay thermoplastic nanocomposites is investigated. A specifically designed fixture consisting of two drums (SER Universal Testing Platform) mounted on a TA Instruments ARES rotational rheometer was used to measure the transient uniaxial extensional viscosity of...

The morphological and rheological properties of thermoplastic elastomer nanocomposites (TPE nanocomposites) were studied using different viscosities of polypropylene (PP) and ethylene-propylene-diene monomer (EPDM) rubber content (20, 40, 60 wt%). The components, namely EPDM, PP, Cloisite 15A, and maleic anhydride-modified PP as compatibilizer, wer...

In this work, three coupling agents presenting different grafting contents and molecular weights were used to prepare linear low density polyethylene (LLDPE)/linear low density polyethylene grafted with maleic anhydride (LLDPE-g-MAH)/montmorillonite nanocomposites with various morphologies. The clay dispersion was analyzed at the micrometric level...

This paper deals with the bubble instabilities induced by cooling airflow rate at different take-up-ratio (TUR) and blow-up-ratio (BUR) conditions in the film-blowing process. Experimental methods to monitor the on-site bubble instability included an in-line scanning camera system to record the bubble oscillation and a manometer mounted on the die...

Alkyl pyridinium, 1-vinyl alkyl imidazolium, 1,3-dialkyl imidazolium, and tetraalkyl phosphonium bromides were successfully used as intercalants for the preparation of highly thermally stable organophilic montmorillonites. Nanocomposites of linear low density polyethylene (LLDPE) and linear low density polyethylene grafted with maleic anhydride (LL...

The thermal stability of organically modified layered silicates is determinant for processing polymer nanocomposites and is believed to play a key role on their properties. In this work, alkyl phosphonium, alkyl pyridinium and dialkyl imidazolium surfactants were used as intercalating agents for the preparation of highly thermally stable organophil...

Effects of organoclay contents on the startup flow properties of layered nano-scale particles in the simple shear mode are investigated. The addition of small amounts of nanoclays to polypropylene melts was found to dramatically change the flow characteristics and creates stress overshoots at large shear rates. A rheological model, initially develo...

The air ring design directly affects the aerodynamic phenomena in the film blowing process. In this study, the effects of impinging jets on heat transfer are explored taking into account the influence of cooling on the bubble shape, by comparing the characteristics and performance of flows produced by single and dual orifice air rings. The aerodyna...

The objective in this study is to establish a model for the prediction of tensile properties using various types of polyethylene films (LLDPE, HDPE, and LDPE). A series of blown films were produced by varying three process parameters: take-up ratio, blow-up ratio, and frost line height. The tensile properties of the resulting films were investigate...

Molecular orientation and structure development during film blowing have a major effect on mechanical and physical properties of polyethylene films. In this work the structures and morphology of three different polyethylene blown films; linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), and high density polyethylene (HDPE) we...

Ultrafine metal powders have been identified as very promising fuels for future energetic material formulations. However, the large specific surface area that gives these powders a high reactivity also makes them particularly difficult to remain in a nonoxidized state. They also agglomerate easily during compounding processes due to strong particle...

This study examines the rheological and morphological properties of dynamically vulcanized nanocomposite thermoplastic elastomers (TPV nanocomposites) based on PP/EPDM. Rubber contents of 20, 40, and 60 % were used with polypropylene of different viscosities at 2 wt.% of nanoclay. We performed rheological and morphological characterizations on the...

Thermoplastic vulcanized (TPV) nanocomposites were prepared in a laboratory mixer using EPDM, polypropylene of different viscosities, maleic anhydride modified polypropylene, an organo-clay, and a sulfur-based curing system. Based on the obtained results from X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy (S...

A Computational Fluid Dynamics (CFD) technique using a renormalization group (RNG) k-ε model and Fluent software was employed to analyze numerically the effects of aerodynamics on the air ring cooling system of a film blowing process. An in-line scanning camera system developed in our lab was used to study experimentally the detailed dynamics of bu...

focus ion beam; transmission electron microscopy; polymer nanocomposites; poly(hydrogen methyl siloxane); encapsulation. T his paper deals with preparation of PE clay nanocomposite specimen for trans-mission electron microscopy (TEM) and studying the difference between disper-sion of clay in low density polyethylene using poly(hydrogen methyl silox...

A series of blown films were produced by varying three key parameters: take-up ratio (TUR), blow-up ratio (BUR), and frost line height (FLH). The tensile properties of the resulting films were investigated in relation to their microstructure characteristics. The orientation parameters of the films were measured by XRD and birefringence. They were d...

A numerical analysis using a renormalization group (RNG), k-ε model and Fluent software was performed to predict the static pressure distribution around the bubble as well as the flow field of cooling air in the film blowing process. Bubble instabilities were experimentally studied using an in-line scanning camera system developed in our laboratory...

The thermal and rheological properties of two types of metallocene-catalyzed linear low-density PEs (mLLDPEs) and two LDPEs, as well as their blends, were studied using differential scanning calorimeter (DSC) measurements and rheometry. The DSC results showed that the mLLDPE-1 based on the hexene comonomer is immiscible with both LDPEs in crystalli...

Despite the fast growth of co-extruded film production, little research work has been devoted to this process. Films of LDPE, ULDPE, LDPE/ULDPE and ULDPE/LDPE were produced at various processing conditions. A continuous experimental set up was used to evaluate the in-plane birefringence during bubble formation. The data collected were used to deriv...

We evaluated the inline birefringence of two blend systems in film blowing. The first system consisted of a metallocene catalyzed linear low density polyethylene (mLLDPE-1) and a low density polyethylene (LDPE-1); the second one was made of a metallocene catalyzed polyethylene containing sparse long chain branches (mLLDPE-2) and another low density...

This paper discusses the implementation of a self-directed learning strategy for instruction in an introductory materials science course. Student's performance metrics are directly compared to those from a more traditional lecture-oriented course. The raw data reveal that the students who have chosen the self-directed learning version of the course...

A numerical analysis using a renormalization group (RNG) k-ε model and Fluent software was performed on the air ring cooling system of the film blowing process. The calculations were in a good agreement with the experimental results to predict maximum air velocities along the bubble surface at different axial distance from the die. Outside of the a...

In order to develop correlations between the properties and microstructural characteristics of polyethylene (PE) blown films, three polymers were evaluated in this study: LDPE, LLDPE and HDPE. Series of blown films were produced at different process conditions. Morphological characteristics of the films were analyzed using SEM and AFM. Herman's ori...

Thermoplastic elastomer nanocomposites based on dynamically vulcanized PP/EPDM with three different viscosity ratio and nanoclay content have been prepared by a melt compounding process. Based on the results of X-ray diffraction measurements, dynamic mechanical testing and thermal characterization, the microstructure of the prepared nanocomposite w...

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The theological behavior of fiber suspensions in a Newtonian fluid is compared with the simulations results of two families of models. The well-known Folgar-Tucker model for fiber motion, combined with the Lipscomb constitutive equation, was used and compared to an extended Jeffery model developed by Grmela et al. (2004). The high shear-thinning be...

The evaluation of filler dispersion in compounding machines is an important part of their design. Calcium carbonate–filled polypropylene (PP) was used as a model compound to study filler dispersion. The evolution of dispersion was followed in a twin-screw extruder where several types of mixing sections were evaluated. Reverse kneading blocks were f...

In this paper, the performance of a new in-line scanning camera system for the study of various bubble instabilities in film blowing extrusion is critically evaluated. Three commercial film-grade polyethylenes, LmPE, LLDPE and LDPE, were used to generate the bubble instabilities. Reliable and objective criteria for differentiating various bubble in...

The aim of this work is to correlate the rheological properties and processability of various polyethylenes during the film-blowing process. The effect of rheology on the kinematics and dynamics of film blowing for five different polyethylene resins has been extensively studied using a fully instrumented laboratory unit. The complex viscosity, shea...

Particle size distribution strongly affects physical and mechanical properties of filled polymers. A new model has been developed to predict agglomerate size distribution in a twin-screw extruder (TSE). The model considers the break-up and erosion processes and it uses agglomerate size population balance in its mathematical formulation. The model p...

In this work, bubble instabilities of metallocene and Ziegler-Natta catalyzed polyethylenes (PEs) were studied by using an in-line scanning camera. Levels of long chain branching (LCB) and breadth of molecular weight distribution (MWD) of PEs were systematically varied to study their effects on bubble instabilities. Gel permeation Chromatograph tra...

We present results of a study on the stick-slip phenomenon observed for two linear polyethylenes (HDPE and LLDPE). Experiments were carried out in a single-screw extruder using dies of different diameters and LID ratios. The pressure and the mass flow rate have been measured simultaneously and the instant mass flow rate was determined using laser D...

Particle size distribution affects strongly physical and mechanical properties of filled polymers. The proposed model uses agglomerate size population balance in its new mathematical formulation expressing agglomeration, break-up and erosion as an evolution of one particle subjected to mean-filed type interaction with others. The erosion parameters...

This paper describes an original on-line video device developed in order to study bubble instabilities occurring in the film blowing process, taking into account their three-dimensional behavior For a linear low-density polyethylene, two forms of instabilities and combination have been observed: draw resonance and helical instability. These instabi...

Compounding of highly filled minerals in a polymeric matrix has never been an easy task. The objective of this work was to build a theoretical model to predict the evolution of dispersion of an inorganic filler in a polymer matrix along a twin-screw extruder as a function of the screw geometry and processing conditions. We developed a general kinet...

Fiber degradation of injection molded fiber reinforced polystyrene has been analyzed using a statistical approach. Results showed that fiber concentration as well as injection speed are responsible for the onset of fiber degradation. The same experimental design has been used to evaluate the effects of injection processing parameters on mechanical...

Using mass conservation and Darcy's law to describe flow through isotropic porous media leads to a Laplace equation, which may be solved numerically at each time step using the boundary element method. For anisotropic porous media in which the permeability matrix is symmetric, the problem can be solved in the same way by rotating and stretching the...

The dynamic friction coefficients of several polymers have been investigated using a specific rotating device similar to an extruder. The increase in temperature during the measurements made it necessary to develop a theoretical approach in order to interpret the experimental data correctly. The rotation speed and particle shapes were found to have...

Highly filled calcium carbonate (CaCO3)/polypropylene (PP) blends were compounded using an intermeshing corotating twin-screw extruder. The effect of screw configuration, rotation speed, flow rate, filler feed port position and barrel temperature on dispersion of calcium carbonate into polypropylene was investigated. A method based on image analysi...