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Papers by Pierre-etienne Bourban

Research paper thumbnail of An integrated processing technique for manufacturing of complex shaped composites

Research paper thumbnail of Andreas Schmocker,a,b, * Azadeh Khoushabi,b,c Constantin Schizas,d Pierre-Etienne Bourban,c

Photopolymerization is commonly used in a broad range of bioapplications, such as drug delivery, ... more Photopolymerization is commonly used in a broad range of bioapplications, such as drug delivery, tissue engineering, and surgical implants, where liquid materials are injected and then hardened by means of illumination to create a solid polymer network. However, photopolymerization using a probe, e.g., needle guiding both the liquid and the curing illumination, has not been thoroughly investigated. We present a Monte Carlo model that takes into account the dynamic absorption and scattering parameters as well as solid-liquid boundaries of the photopolymer to yield the shape and volume of minimally invasively injected, photopolymerized hydrogels. In the first part of the article, our model is validated using a set of well-known poly(ethylene glycol) dimethacrylate hydrogels showing an excellent agreement between simulated and experimental volume-growthrates. In the second part, in situ experimental results and simulations for photopolymerization in tissue cavities are presented. It was found that a cavity with a volume of 152 mm 3 can be photopolymerized from the output of a 0.28-mm 2 fiber by adding scattering lipid particles while only a volume of 38 mm 3 (25%) was achieved without particles. The proposed model provides a simple and robust method to solve complex photopolymerization problems, where the dimension of the light source is much smaller than the volume of the photopolymerizable hydrogel.

Research paper thumbnail of Integration of thermoplastic polymers and composites

Research paper thumbnail of Mise en oeuvre intégrée des polymères et composites

Research paper thumbnail of High rate bladder moulding of thermoplastic composites

Research paper thumbnail of Interfacial Characte Rization of Non-Isothermally Fusion Bonded Hard a ND Soft Thermoplasti CS : Implications for Fus Ed Deposition

Although fused deposition modeling (FDM) is of great interest for the cost-effective manufacture ... more Although fused deposition modeling (FDM) is of great interest for the cost-effective manufacture of polymer parts with complex customized geometries, it currently provides insufficient mechanical integrity for the production of high performance functional structures, and is restricted to too limited a range of materials. The present work is aimed at investigating the suitability of new combinations of hard and soft thermoplastics for FDM. To this end, nonisothermal fusion bonding of polypropylene (iPP) and a thermoplastic elastomer (TPE) with a continuous plasticized iPP matrix was investigated by overinjecting the TPE onto a solid iPP insert. The influence of temperature and pressure was evaluated by tensile testing of butt joint specimens, and optical and electron microscopy. Interface temperatures approaching the iPP melting point gave high bond strengths for hold pressures above 200 bars, resulting in cohesive failure in the TPE as well as adhesive failure at the interface. The ...

Research paper thumbnail of Mise en oeuvre intégrée de composites thermoplastiques

Research paper thumbnail of Complex hollow shapes from thermoplastic composites

To apply continuous fibre reinforced thermoplastic composites to complex hollow geometries, a bla... more To apply continuous fibre reinforced thermoplastic composites to complex hollow geometries, a bladder inflation moulding technique (BIM) has been developed. Braided textile preforms based on stretch-broken commingled or hybrid yarns were used to minimise inplane shear deformation and wrinkling during the moulding process. Hollow parts with varying cross-section and concave and convex sharp angles were successfully produced. The technique has shown to offer short cycle times (3 minutes) at low pressures (10 bar) for composites based on commingled carbon and polyamide 12 preforms. The effect of processing conditions on void content in the final part has been investigated. The braiding angle, fibre volume fraction and yarn thickness were varied and their relative importance on the mechanical properties of braided tubes observed. The BIM technique has been demonstrated as a cost-effective route for producing thin-walled composite parts with evolving cross-sections.

Research paper thumbnail of Integrated processing: high performance composites by injection moulding

Research paper thumbnail of In-situ polymerisation of polyamide 12 for thermoplastic composites

Keywords: polyamide 12 (PA12) ; thermoplastic ; polymerisation ; viscosity ; TTT diagram Referenc... more Keywords: polyamide 12 (PA12) ; thermoplastic ; polymerisation ; viscosity ; TTT diagram Reference EPFL-CONF-179018 Record created on 2012-06-29, modified on 2016-08-09

Research paper thumbnail of Fiber/matrix wetting and adhesion within thermoplastic commingled yarns

Research paper thumbnail of Cellular biodegradable polymer nanocomposite scaffolds

Research paper thumbnail of Novel thermoplastic sandwich preforms for three-dimensional forming

Journées Transalpines des Polymères, 2000

These Ecole polytechnique federale de Lausanne EPFL, n° 2109 (1999)Faculte des sciences et techni... more These Ecole polytechnique federale de Lausanne EPFL, n° 2109 (1999)Faculte des sciences et techniques de l'ingenieurJury: Pierre-Etienne Bourban, Jacques Giovanola, Heinrich Hofmann, Jorg Spichtig, Ignaas Verpoest Public defense: 2000-1-20 Reference doi:10.5075/epfl-thesis-2109Print copy in library catalog Record created on 2005-03-16, modified on 2016-08-08

Research paper thumbnail of Bioresorbable polymer composites for bone tissue engineering applications

Research paper thumbnail of In vivo evaluation of human fetal bone cells for bone tissue engineering applications

Research paper thumbnail of Osteoinductive effect of in vivo mechanical stimulation for bone tissue engineering

Research paper thumbnail of Mechanical stimulus as potent agent for bone formation inside scaffold for bone tissue engineering application

Research paper thumbnail of Shear thickening fluids as a tunable damping element: experimental results and modeling - art. no. 652513

Active and Passive Smart Structures and Integrated Systems 2007, 2007

Highly concentrated silica suspensions are well-known for their pronounced shear-thickening behav... more Highly concentrated silica suspensions are well-known for their pronounced shear-thickening behavior beyond a certain shear rate or stress, at which a significant and simultaneous increase of the stiffness and damping properties are observed. In the present work, the integration of shear-thickening fluids (STFs) into composite structures has been investigated with the aim of tuning part stiffness and damping capacity under

Research paper thumbnail of Synthesis and Photopolymerization of Tween 20 Methacrylate/N-vinyl-2-Pyrrolidone Blends

Materials Science and Engineering: C, 2012

Poly(oxyethylene 20 sorbitan) monolaurate (Tween® 20) methacrylates were synthesized by coupling ... more Poly(oxyethylene 20 sorbitan) monolaurate (Tween® 20) methacrylates were synthesized by coupling methacryloyl chloride (MeOCl) to Tween 20 in the presence of 4-(N,N-dimethylamino) pyridine, using THF as a solvent, in order to investigate their suitability as precursors for photopolymerizable hydrogels in tissue engineering applications. The degree of substitution could be controlled by adjusting the molar ratio of MeOCl and Tween 20, giving three different monomers: Tween 20 monomethacrylate, Tween 20 dimethacrylate and Tween 20 trimethacrylate. Combined 1 H NMR and MALDI-TOF MS confirmed these monomers to be of high purity and to have polydispersities less than 1.3. It was shown that aqueous solutions of the monomers were photoactive, all the methacrylate groups reacting within 30 minutes exposure to a UV light intensity of 145 mW/cm 2. Aqueous Tween 20 trimethacrylate was then combined with N-vinyl-2-pyrrolidone (NVP), giving tough copolymer hydrogels on photopolymerization, whose swelling ratios and swelling rates could be tuned by varying the Tween 20 trimethacrylate content. The use of a flexible spacer with a multifunctional monomer gives a permanent three-dimensional network, whilst maintaining degrees of swelling of between 60 and 85%, with potential for a wide range of biological and non-biological applications.

Research paper thumbnail of Cellular composites based on continuous fibres and bioresorbable polymers

Composites Part A: Applied Science and Manufacturing, 2008

Biocompatible composites, whose porosity and fibre fraction can be tailored over a large range an... more Biocompatible composites, whose porosity and fibre fraction can be tailored over a large range and whose mechanical resistance is comparable to that of natural bone, were processed with poly(lactic acid) (PLA) and continuous glass fibres. The processing steps included the winding of unidirectional preforms made of mingled fibres, and a subsequent supercritical gas foaming. Results showed that the fibres were mainly distributed within the cell walls without crossing the pores. Therefore, a model combining the buckling of composite columns into a polymer foam structure was proposed in order to predict the final mechanical properties. Experimental results revealed the high reinforcing effect of continuous glass fibres in PLA foams and validated the model. Cellular composites are of interest for biomedical and lightweight applications.

Research paper thumbnail of An integrated processing technique for manufacturing of complex shaped composites

Research paper thumbnail of Andreas Schmocker,a,b, * Azadeh Khoushabi,b,c Constantin Schizas,d Pierre-Etienne Bourban,c

Photopolymerization is commonly used in a broad range of bioapplications, such as drug delivery, ... more Photopolymerization is commonly used in a broad range of bioapplications, such as drug delivery, tissue engineering, and surgical implants, where liquid materials are injected and then hardened by means of illumination to create a solid polymer network. However, photopolymerization using a probe, e.g., needle guiding both the liquid and the curing illumination, has not been thoroughly investigated. We present a Monte Carlo model that takes into account the dynamic absorption and scattering parameters as well as solid-liquid boundaries of the photopolymer to yield the shape and volume of minimally invasively injected, photopolymerized hydrogels. In the first part of the article, our model is validated using a set of well-known poly(ethylene glycol) dimethacrylate hydrogels showing an excellent agreement between simulated and experimental volume-growthrates. In the second part, in situ experimental results and simulations for photopolymerization in tissue cavities are presented. It was found that a cavity with a volume of 152 mm 3 can be photopolymerized from the output of a 0.28-mm 2 fiber by adding scattering lipid particles while only a volume of 38 mm 3 (25%) was achieved without particles. The proposed model provides a simple and robust method to solve complex photopolymerization problems, where the dimension of the light source is much smaller than the volume of the photopolymerizable hydrogel.

Research paper thumbnail of Integration of thermoplastic polymers and composites

Research paper thumbnail of Mise en oeuvre intégrée des polymères et composites

Research paper thumbnail of High rate bladder moulding of thermoplastic composites

Research paper thumbnail of Interfacial Characte Rization of Non-Isothermally Fusion Bonded Hard a ND Soft Thermoplasti CS : Implications for Fus Ed Deposition

Although fused deposition modeling (FDM) is of great interest for the cost-effective manufacture ... more Although fused deposition modeling (FDM) is of great interest for the cost-effective manufacture of polymer parts with complex customized geometries, it currently provides insufficient mechanical integrity for the production of high performance functional structures, and is restricted to too limited a range of materials. The present work is aimed at investigating the suitability of new combinations of hard and soft thermoplastics for FDM. To this end, nonisothermal fusion bonding of polypropylene (iPP) and a thermoplastic elastomer (TPE) with a continuous plasticized iPP matrix was investigated by overinjecting the TPE onto a solid iPP insert. The influence of temperature and pressure was evaluated by tensile testing of butt joint specimens, and optical and electron microscopy. Interface temperatures approaching the iPP melting point gave high bond strengths for hold pressures above 200 bars, resulting in cohesive failure in the TPE as well as adhesive failure at the interface. The ...

Research paper thumbnail of Mise en oeuvre intégrée de composites thermoplastiques

Research paper thumbnail of Complex hollow shapes from thermoplastic composites

To apply continuous fibre reinforced thermoplastic composites to complex hollow geometries, a bla... more To apply continuous fibre reinforced thermoplastic composites to complex hollow geometries, a bladder inflation moulding technique (BIM) has been developed. Braided textile preforms based on stretch-broken commingled or hybrid yarns were used to minimise inplane shear deformation and wrinkling during the moulding process. Hollow parts with varying cross-section and concave and convex sharp angles were successfully produced. The technique has shown to offer short cycle times (3 minutes) at low pressures (10 bar) for composites based on commingled carbon and polyamide 12 preforms. The effect of processing conditions on void content in the final part has been investigated. The braiding angle, fibre volume fraction and yarn thickness were varied and their relative importance on the mechanical properties of braided tubes observed. The BIM technique has been demonstrated as a cost-effective route for producing thin-walled composite parts with evolving cross-sections.

Research paper thumbnail of Integrated processing: high performance composites by injection moulding

Research paper thumbnail of In-situ polymerisation of polyamide 12 for thermoplastic composites

Keywords: polyamide 12 (PA12) ; thermoplastic ; polymerisation ; viscosity ; TTT diagram Referenc... more Keywords: polyamide 12 (PA12) ; thermoplastic ; polymerisation ; viscosity ; TTT diagram Reference EPFL-CONF-179018 Record created on 2012-06-29, modified on 2016-08-09

Research paper thumbnail of Fiber/matrix wetting and adhesion within thermoplastic commingled yarns

Research paper thumbnail of Cellular biodegradable polymer nanocomposite scaffolds

Research paper thumbnail of Novel thermoplastic sandwich preforms for three-dimensional forming

Journées Transalpines des Polymères, 2000

These Ecole polytechnique federale de Lausanne EPFL, n° 2109 (1999)Faculte des sciences et techni... more These Ecole polytechnique federale de Lausanne EPFL, n° 2109 (1999)Faculte des sciences et techniques de l'ingenieurJury: Pierre-Etienne Bourban, Jacques Giovanola, Heinrich Hofmann, Jorg Spichtig, Ignaas Verpoest Public defense: 2000-1-20 Reference doi:10.5075/epfl-thesis-2109Print copy in library catalog Record created on 2005-03-16, modified on 2016-08-08

Research paper thumbnail of Bioresorbable polymer composites for bone tissue engineering applications

Research paper thumbnail of In vivo evaluation of human fetal bone cells for bone tissue engineering applications

Research paper thumbnail of Osteoinductive effect of in vivo mechanical stimulation for bone tissue engineering

Research paper thumbnail of Mechanical stimulus as potent agent for bone formation inside scaffold for bone tissue engineering application

Research paper thumbnail of Shear thickening fluids as a tunable damping element: experimental results and modeling - art. no. 652513

Active and Passive Smart Structures and Integrated Systems 2007, 2007

Highly concentrated silica suspensions are well-known for their pronounced shear-thickening behav... more Highly concentrated silica suspensions are well-known for their pronounced shear-thickening behavior beyond a certain shear rate or stress, at which a significant and simultaneous increase of the stiffness and damping properties are observed. In the present work, the integration of shear-thickening fluids (STFs) into composite structures has been investigated with the aim of tuning part stiffness and damping capacity under

Research paper thumbnail of Synthesis and Photopolymerization of Tween 20 Methacrylate/N-vinyl-2-Pyrrolidone Blends

Materials Science and Engineering: C, 2012

Poly(oxyethylene 20 sorbitan) monolaurate (Tween® 20) methacrylates were synthesized by coupling ... more Poly(oxyethylene 20 sorbitan) monolaurate (Tween® 20) methacrylates were synthesized by coupling methacryloyl chloride (MeOCl) to Tween 20 in the presence of 4-(N,N-dimethylamino) pyridine, using THF as a solvent, in order to investigate their suitability as precursors for photopolymerizable hydrogels in tissue engineering applications. The degree of substitution could be controlled by adjusting the molar ratio of MeOCl and Tween 20, giving three different monomers: Tween 20 monomethacrylate, Tween 20 dimethacrylate and Tween 20 trimethacrylate. Combined 1 H NMR and MALDI-TOF MS confirmed these monomers to be of high purity and to have polydispersities less than 1.3. It was shown that aqueous solutions of the monomers were photoactive, all the methacrylate groups reacting within 30 minutes exposure to a UV light intensity of 145 mW/cm 2. Aqueous Tween 20 trimethacrylate was then combined with N-vinyl-2-pyrrolidone (NVP), giving tough copolymer hydrogels on photopolymerization, whose swelling ratios and swelling rates could be tuned by varying the Tween 20 trimethacrylate content. The use of a flexible spacer with a multifunctional monomer gives a permanent three-dimensional network, whilst maintaining degrees of swelling of between 60 and 85%, with potential for a wide range of biological and non-biological applications.

Research paper thumbnail of Cellular composites based on continuous fibres and bioresorbable polymers

Composites Part A: Applied Science and Manufacturing, 2008

Biocompatible composites, whose porosity and fibre fraction can be tailored over a large range an... more Biocompatible composites, whose porosity and fibre fraction can be tailored over a large range and whose mechanical resistance is comparable to that of natural bone, were processed with poly(lactic acid) (PLA) and continuous glass fibres. The processing steps included the winding of unidirectional preforms made of mingled fibres, and a subsequent supercritical gas foaming. Results showed that the fibres were mainly distributed within the cell walls without crossing the pores. Therefore, a model combining the buckling of composite columns into a polymer foam structure was proposed in order to predict the final mechanical properties. Experimental results revealed the high reinforcing effect of continuous glass fibres in PLA foams and validated the model. Cellular composites are of interest for biomedical and lightweight applications.