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Hengsberger Stefan

Ordentlicher Professor FH/Institutsleiter

Main skills

Functional Surfaces and Materials

Main contract

Ordentlicher Professor FH/Institutsleiter

Phone: +41 26 429 67 23

Desktop: BFA_1A_124

Haute école d'ingénierie et d'architecture de Fribourg
Boulevard de Pérolles 80, 1700 Fribourg, CH

Institute
iRAP - Institut de recherches appliquées en plasturgie

MSc HES-SO en Engineering - HES-SO Master

Physique des matériaux et des dispositifs électroniques

BSc HES-SO en Chimie - Haute école d'ingénierie et d'architecture de Fribourg

Nanotechniques et Applications Industrielles (NANO)

BSc HES-SO en Génie mécanique - Haute école d'ingénierie et d'architecture de Fribourg

Biomécanique et Nanomécanique

Ongoing

EUREKA Super-Moulds

Role: Main Applicant

Financement: Danish Innovation fund & Innosuisse

Description du projet :

The EUREKA Super-Moulds project is jointly financed by the Innovation Fund Denmark and the Swiss innovation funding Innosuisse. The project has started in January 2017 with a total duration of four years. This collaboration of seven Danish and three Swiss partners focuses on the optimization of the plastic injection process by optimizing the mould surface treatments. Demoulding of complex plastic parts is complicated by sticking and high friction between the polymer and the mould surface resulting in long cooling times to avoid deformation, process interruptions due to cleaning and reduced mould service life. The aim of this project is to tailor mould surface coatings and textures to achieve optimum anti-stick properties for a set of commercial plastic types. This outstanding consortium is based on a complete value chain approach within plastic processing; beginning with the supplier of polymer material (Dupont de Nemours-CH), the stakeholders in surface texturing technology (Georg Fischer Machining Solutions-CH) and coating (Tribology Center, Danish Technological Institute-DK) to the supplier of moulding tools (Winther Mould Technology-DK). The Danish National Metrology institute (DFM) contributes with their expertise in surface roughness analysis and the academic partner (iRAP-CH) centralizes the injection tests. The end users (Novo Nordisk, SP Moulding and Giboplast) contribute to the definition of the appropriate plastic part geometries to study and validate the final results under production conditions. The Danish Plastics Federation and the Swiss Plastics Cluster will foster the market penetration by publishing the results.

Research team within HES-SO: Hengsberger Stefan

Montant global du projet: 485'000 CHF

Statut: Ongoing

Completed

Caractérisation des dépôts résiduels sur les moules d'injection et test des modifications de surfaces anti-adhérentes

AGP

Role: Main Applicant

Financement: Mecaplast SA; Wago Contact SA; Saia-Burgess Controls AG; PST-FR

Description du projet : Lors du procédé d'injection, des dépôts se forment à l'intérieur des canaux d'évacuation de gaz. Leur accumulation occasionne des défauts de pièces et leur élimination nécessite des nettoyages réguliers. Une solution à problème résultera en une production de meilleure qualité, plus économique et plus écologique. Ce projet vise à effectuer une analyse chimique des polymères et des dépôts résiduels, à analyser le marché au niveau des revêtements existants et à caractériser leur efficacité en tant que couche anti-adhérente.

Research team within HES-SO: Clément Eric , Hengsberger Stefan , Corpataux Dominique , Raetzo Raphaël

Partenaires académiques: FR - EIA - ITIN - Systèmes électroniques intégrés; Adolphe Merkle Institute

Durée du projet: 01.06.2009 - 31.12.2009

Montant global du projet: 75'000 CHF

Statut: Completed

Micro et Nanostructuration des surfaces

AGP

Role: Main Applicant

Financement: HES-SO Rectorat; FR - Ecole d'ingénieurs de Fribourg; GE Haute école du paysage, d'ingénierie et d'architecture

Description du projet : Les techniques courantes de structuration de surfaces permettent essentiellement la génération de structures régulières, périodiques et uniformes possédant ainsi une certaine anisotropie. Pour de nombreuses applications industrielles ' parmi eux la structuration de surfaces d`implants - il est néanmoins indispensable de générer des surfaces avec des structures d'une taille moyenne définie mais d'une forme plus aléatoire. En collaboration avec le CSEM (Neuchâtel), l'EIA-Fribourg a récemment lancé le développement d'une technique de micro et nanostructuration qui permet une structuration de caractère isotrope, peu couteuse et rapide.poursuive le développement de cette technique. Ce projet vise à identifier les paramètres critiques du processus de nano/micro-structuration et ainsi qu'à optimiser le processus. Actuellement cette technique permet la structuration des surfaces planes. Ce projet vise également à assurer une bonne fiabilité sur la reproduction et à effectuer une nano/micro structuration des surfaces non-planes. Vue le potentiel d'application dans le secteur biomédical il est important que la HES-SO

Research team within HES-SO: Hengsberger Stefan , Schroeter Nicolas , Bourrier Hervé , Jobin Marc , Foschia Raphael

Partenaires académiques: EIG - INIS

Durée du projet: 01.09.2006 - 31.08.2007

Montant global du projet: 74'700 CHF

Statut: Completed

Imagerie des propriétés mécaniques du micro au nano

AGP

Role: Co-applicant

Financement: HES-SO Rectorat; FR - Ecole d'ingénieurs de Fribourg; GE Haute école du paysage, d'ingénierie et d'architecture; GE Haute école du paysage, d'ingénierie et d'architecture

Description du projet : Le projet vise : - à concevoir et implémenter un système d'imagerie des propriétés mécanique en haute résolution, basé sur un nanoindenteur et un scanner de microscope à force atomique. -à adapter les modèles théoriques existants concernant la modulation de force pour interpréter quantitativement les images obtenues en modulation de déplacement Toutes les informations relevantes se trouvent dans le fichier annexé

Research team within HES-SO: Hengsberger Stefan , Jobin Marc , Foschia Raphael

Durée du projet: 01.09.2005 - 30.06.2006

Montant global du projet: 55'420 CHF

Statut: Completed

2023

Tunable and biodegradable poly(ester amide)s for disposable facemasks

Scientific paper ArODES

Esteban Alvarez Seoane, Alessandro Cattaneo, Fabien Neuenschwander, Lucien Blanchard, Tatiana Nogueira Matos, Laure Jeandupeux, Gianni Fiorucci, Maryam Tizgadam, Kelly Tran, Pierre-Louis Sciboz, Luce Albergati, Jérôme Charmet, Roger Marti, Stefan Hengsberger

Macromolecular Materials and Engineering, 2300375

Link to the publication

Summary:

The widespread use of disposable facemasks during the COVID-19 pandemic has led to environmental widespread concern due to microplastic pollution. Biodegradable disposable facemasks are a first step to reducing the environmental impact of pandemics. In this paper we present high-performance facemask components based on novel poly(ester amide) (PEA) grades synthesized from bio-sourced materials and processed into non-woven facemask components. PEA based polymers present an excellent compromise between mechanical performance and biodegradability. Importantly, the properties of the PEA can easily be tuned by changing the ratio of the ester and amides, or variation of diol and diacid part. We synthesized seven polymers which we optimized for biodegradability and processability. Among them, two grades combined electrospinning process compatibility with full degradation within 35 days, using a normalized biodegradation test. The ultra-thin filters thus developed were evaluated for performance on a custom-made characterization bench. The filters achieved a microparticle capture efficiency and breathability comparable to commercial filters. Another PEA grade was optimized to reach optimal visco-thermal properties that made it compatible with solvent-free melt-spinning process as demonstrated with continuous fibres production. Overall, our environmentally friendly solution paves the way for the fabrication of high-performance fibres with excellent biodegradability for the next generation facemasks.

2022

A near-infrared mechanically switchable elastomeric film as a dynamic cell culture substrate

Scientific paper ArODES

Giovanni Spiaggia, Patricia Taladriz-Blanco, Stefan Hengsberger, Dedy Septiadi, Christoph Geers, Aaron Lee, Barbara Rothen-Rutishauser, Alke Petri-Fink

Biomedicines, 2023, vol. 1, no. 1, article no. 30

Link to the publication

Summary:

Commercial static cell culture substrates can usually not change their physical properties over time, resulting in a limited representation of the variation in biomechanical cues in vivo. To overcome this limitation, approaches incorporating gold nanoparticles to act as transducers to external stimuli have been employed. In this work, gold nanorods were embedded in an elastomeric matrix and used as photothermal transducers to fabricate biocompatible light-responsive substrates. The nanocomposite films analysed by lock-in thermography and nanoindentation show a homogeneous heat distribution and a greater stiffness when irradiated with NIR light. After irradiation, the initial stiffness values were recovered. In vitro experiments performed during NIR irradiation with NIH-3T3 fibroblasts demonstrated that these films were biocompatible and cells remained viable. Cells cultured on the light stiffened nanocomposite exhibited a greater proliferation rate and stronger focal adhesion clustering, indicating increased cell-surface binding strength.

Influence of Si3N4 nanoparticles on morphology, hardness and corrosion resistance of electrodeposited Ni-Co- Si3N4

Scientific paper ArODES

Maryam Tizgadam, Stefan Hengsberger, Ali Rasooli, Somayeh Ahmadiyeh

International Journal of Electrochemical Science, 2022, vol. 17, no. 10, article no. 221062

Link to the publication

Summary:

The main goal of this study was based on estimating the influence of Si3N4 reinforcement nanoparticles on the mechanical and electrochemical properties of Ni-Co-Si3N4 nanocomposite coatings. Ni-Co-Si3N4 nanocomposite coatings were electrodeposited on copper from a modified Watts bath containing Si3N4 particles by direct current (DC). The effect of Si3N4nano-particles on the properties of Ni-Co coatings was studied. Surface morphology, chemical composition, grain size and corrosion resistance of Ni-Co and Ni-Co-Si3N4 nanocomposite coatings were investigated by scanning electron microscope (SEM), energy dispersive X-ray detector (EDS) coupled with SEM, X-ray diffraction analysis (XRD) and electrochemical impedance measurements, respectively. It was found that surface morphologies of NiCo coatings were changed by using nano-particles. There was no difference in the microstructure of coatings, both electrodeposited Ni-Co and Ni-Co-Si3N4 nanocomposite coating's crystalline structure was face-centered cubic (FCC). Based on impedance measurements, it revealed that the corrosion resistance of nanocomposite coatings was more than that of electrodeposited Ni-Co coating. The microhardness of the nanocomposite coatings (678 HV) was higher than that of Ni-Co (580 HV) due to dispersion-strengthening and matrix grain refining. The best mechanical and corrosion resistance properties achieved at the Ni-Co-7.9 wt% Si3N4 nanocomposite coating.

2020

Laser texturing allows for reducing injection cycle time by 15%

Professional paper ArODES

Stefan Hengsberger, Sascha Louring

Muoviplast, 2020, vol. 6, pp. 16-17

Link to the publication

Summary:

A defined laser texturing of a mould insert has demonstrated positive effects on the productivity when applied in combination with the DuPont grade Zytel(R) HTN51G35HSL NC010, which is PPA polymer containing 35 % glass fibers. A validation test under production conditions has shown that a surface topography tuned with the laser texturing (provided by GF Machining Solutions) has an anti-adhesive effect and allows for a potential gain of 5 seconds cooling time, which corresponds to a cycle time reduction from 33 to 28 seconds or a 15 % productivity increase.

2019

Microparticles as additives for increasing the mechanical stiffness of polypropylene

Scientific paper ArODES

Stefan Hengsberger, Geoffroy Leignel, Eléonore Véron du Breuil, Christophe Cotting, Renaud Meuwly, Jean-Marie Dutoit, Thierry Chappuis

Chimia, 2019, vol. 73, no. 12

Link to the publication

Summary:

Composite materials of polypropylene and mineral microparticles have been generated by compounding and tested in terms of mechanical stiffness. In a first step silica, boehmite and functionalized clay microparticle powder have been mixed with the polymer in a twin-screw compounder. The elastic modulus was highest for mixtures with a microparticle concentration of 5 to 10%w/w. An increase of 25% of the elastic modulus was achieved by simple melt extrusion. In a second step, a maleic anhydride-grafted polypropylene (PP-g-MA) was used as a matrix. When measured by nanoindentation, the pure PP-g-MA matrix showed an elastic modulus twice as high as pure PP, probably because of a partial reticulation. During extrusion, amino-silane functionalized clay microparticles were added to the PP-g-MA matrix and reacted with it by building covalent amide group bonds. The resulting compound material showed an elastic modulus of more than four times the stiffness of pure PP.

2018

Micro- nanotechnology for higher productivity in plastics processing

Professional paper ArODES

Stefan Hengsberger

Micronarc micro-nano Mag, 2018, 3, pp. 74-75

Link to the publication

Summary:

The recently started EUREKA project Super-Moulds represents a perfect example where a full value chain of stakeholders in the Plasturgy sector are reunited and highlights the competencies of the institute for Applied Plastics Research (iRAP) in terms of micronano technology.

2016

Life and death of plastics

Professional paper ArODES

Yvan Mongbanziama, Sandrine Aeby, Matthieu Kaehr, Vincent Pilloud, Jean-Luc Robyr, Bernard Masserey, Stefan Hengsberger, Samuel Roth, Pierre Brodard

CHIMIA International Journal for Chemistry, 2016, vol. 70, no. 9, pp. 649-650

Link to the publication

2018

Tribological study and coatings impact on release forces during injection moulding

Conference ArODES

Lars Pleth Nielsen, Borja Zabala, Klaus Pagh Almtoft, Bjarke Holl Christensen, Mads Rytter, Stefan Hengsberger

Proceedings of the 18th Nordic Symposium on Tribology (NORDTRIB) 2018, 18-21 june, Uppsala University, Uppsala, Sweden

Link to the conference

Summary:

In the present study we compare in situ measured demoulding forces with model tests based on reciprocating pin-on-disc configuration at high temperature simulating the mould/thermoplastic interphase. The ejection force and pin-on-disc friction properties were measured for four industrially relevant polymer types (PP, POM, ABS and TPU). The impact on the ejection force was quantified when adding different surface pretreatments (as machined, grinded, blasted, polished and laser textured) to the involved pin-on-disc surfaces and the injection moulding cores. Different PVD coatings (CrN, CrN-HiPIMS and DLC) combined with post treatment involving high-current implantation of nitrogen were investigated. The results revealed that the ejection force could be lowered by up to 70% for some of the thermoplastic types when applying a combination of a wear-resistant coating and nitrogen ion implantation.

Increasing the injection moulding productivity through EDM surface modulation

Conference ArODES

Umang Maradia, E. Filisetti, Marco Boccadoro, Marc Roten, Jean-Marie Dutoit, Stefan Hengsberger

Proceedings of 19th CIRP Conference on Electro Physical and Chemical Machining, 23-27 April 2018, Bilbao, Spain

Link to the conference

Summary:

The productivity of the injection moulding process is considerably deteriorated due to the demoulding issues as a result of increasing part and polymer complexity. An effective method to overcome some of the issues is the application of coatings on mould surface to reduce adhesion and friction during the moulded part ejection. In such solutions, the mould is coated after the machining by methods such as milling and EDM. In fact, die-sinking EDM is widely used to machine moulds with high accuracy, surface quality and aspect ratios. In this research, a novel method is analysed where the texture of the EDM surface is modulated to achieve desirable surface functionality, leading to reduction of part sticking during ejection in injection moulding. The effect of primary parameters of EDM process on the resulting surface is analysed. It is seen that while the surface amplitude parameters such as Ra and Rz remain similar to the standard eroded surface, the spacing parameter RSm and slope measure RΔq can be modulated. The effect of the surface texture during injection moulding is evaluated by measuring the forces during the ejection stage to characterise part sticking. Similar or considerably reduced ejection forces are observed for the modulated EDM texture compared to the polished surfaces, depending on the polymer type and part geometry. The ejection force observations are correlated to the static and dynamic friction coefficient of surface textures against different polymers. The reduction of ejection forces comparable to the coated surfaces places surface texturing as an effective alternative or a supplement to reduce the demoulding issues and thus increasing the injection moulding productivity and part quality.

Achievements

PEOPLE@HES-SO
Directory and Skills inventory

Hengsberger Stefan

Ordentlicher Professor FH/Institutsleiter

Main skills

Nanotechnology

Tribology

Surface treatment

Functional Surfaces and Materials

Ordentlicher Professor FH/Institutsleiter

PEOPLE@HES-SO Directory and Skills inventory

Hengsberger Stefan

Ordentlicher Professor FH/Institutsleiter

Main skills

Nanotechnology

Tribology

Surface treatment

Functional Surfaces and Materials

Ordentlicher Professor FH/Institutsleiter

PEOPLE@HES-SO
Directory and Skills inventory