Ivica Duretek

Montanuniversität Leoben · Polymer Engineering and Science

Metal material extrusion (MMEX) involves the systematic deposition of material layer by layer, followed by debinding and sintering to produce fully dense metallic parts. The feedstocks, initially comprising metal powder and a binder system, are pivotal in determining processability and final properties. This study utilized polylactic acid (PLA) as...

Biobased plastics have the potential to be sustainable, but to explore their circularity further, current end-of-life options need to be broadened. Mechanical recycling is one of the most accepted methods to bring back plastics into the loop. Polyhydroxybutyrates (PHBs) are biobased and biodegradable in nature with promising properties and varied a...

Measuring the shear viscosity of polymeric melts is an extensive effort frequently performed in high-pressure capillary rheometers, where the pressures required to push the melt through a capillary at various temperatures and volumetric flow rates are recorded. Then, the viscosity values are obtained through Bagley and Weissenberg–Rabinowitsch corr...

The current study presents the effect of the backbone as an important binder component on the mechanical, rheological, and thermal properties of Aluminium (Al) alloy feedstocks. A thermoplastic elastomer (TPE) main binder component was blended with either polypropylene (PP), grafted-maleic anhydride-PP (PPMA), or grafted-maleic anhydride-PPwax (PPM...

Übersichtsartikel zu filamentbasierten 3D-Druckverfahren.

The combination of recycled fiber reinforcement with recycled polymer as a feedstock material for extrusion-based additive manufacturing creates an opportunity for a more sustainable material use. In this study, recycled short carbon fibers were combined with recycled poly(ethylene terephthalate) (PET) to obtain carbon fiber-reinforced PET filament...

The good interaction between the ceramic powder and the binder system is vital for ceramic injection molding and prevents the phase separation during processing. Due to the non-polar structure of polyolefins such as high-density polyethylene (HDPE) and the polar surface of ceramics such as zirconia, there is not appropriate adhesion between them. I...

Poly(ethylene terephthalate) (PET) has wide usage in packaging and fiber industries thanks to its superior mechanical, thermal, and barrier properties. It is also one of the "big five" recyclable plastics with well-established procedures. In many textile and film products, flame retardants (FRs) are added to PET for fire-safe applications. However,...

Fused filament fabrication (FFF) is currently one of the most popular additive manufacturing processes due to its simplicity and low running and material costs. Support structures, which are necessary for overhanging surfaces during production, in most cases need to be manually removed and as such, they become waste material. In this paper, experim...

The production of plastic has grown exponentially over the past few decades and with it the amount of plastic waste leaking in the environment, where it fragments into micro- and nanoplastics. This problematic situation stresses the need for increased plastic collection, recycling and reuse rates. Extrusion-based additive manufacturing (AM) and esp...

The perception of a surface and its haptic properties are significantly influenced by roughness and microstructure, respectively, whereby non-negligible parameters include friction, contact area, temperature, and humidity between the human finger and the examined surface. In particular, for a scientific investigation on haptic influences, the produ...

To achieve future recycling targets and CO2 and waste reduction, the transfer of plastic contained in mixed waste from thermal recovery to mechanical recycling is a promising option. This requires extensive knowledge of the necessary processing depth of mixed wastes to enrich plastics and their processability in polymer processing machines. Also, t...

Epoxy-anhydride vitrimers are covalent adaptable networks, which undergo associative bond exchange reactions at elevated temperature. Their service temperature is influenced by the glass transition temperature (Tg) as well as the topology freezing transition temperature (Tv), at which the covalent bond exchange reactions become significantly fast....

Employment of ready-to-press (RTP) powders are common in the field of hardmetal manufacture. Various grades of such powder products are available on the market for companies without an own production line for the granulation of powders. In our study we employed such RTP powders for compounding with polymers to prepare feedstock and prepared flexibl...

Hardmetal and cermet bodies were printed by fused-filament fabrication (FFF) and composite-extrusion modelling (CEM) in an SDS (shaping – debinding – sintering) process. For FFF the filaments were prepared from hardmetal (WC-10Co) and cermet powder (Ti(C,N)-Co/Ni-based) and organic binder. The CEM feedstock consisted of WC-Co MIM powder. A 3D filam...

Additive manufacturing is fast-growing and a most interesting fabrication technology also for parts prepared out of composite materials. We recently reported on the first ever conducted extrusion-printing techniques on WC-Co-based hardmetals and Ti(C,N)-based cermets. While both materials were prepared with multiphase starting mixtures blended in a...

Hardmetal and cermet bodies were printed by fused-filament fabrication (FFF) and composite-extrusion modelling (CEM) in an SDS (shaping-debinding-sintering) process. For FFF the filaments were prepared from hardmetal (WC-10Co) and cermet powder (Ti(C,N)-Co/Ni-based) and organic binder. The CEM feedstock consisted of WC-Co MIM powder. A 3D filament...

Hardmetal and cermet bodies were printed by fused-filament fabrication (FFF) and composite-extrusion modelling (CEM) in an SDS (shaping-debinding-sintering) process. For FFF the filaments were prepared from hardmetal (WC-10Co) and cermet powder (Ti(C,N)-Co/Ni-based) and organic binder. The CEM feedstock consisted of WC-Co MIM powder. A 3D filament...

Fused filament fabrication (FFF) is a very popular additive manufacturing technique for the production of geometrically complex polymeric parts. FFF can also be used for the production of sintered magnetic parts, as part of the shaping, debinding and sintering (SDS) process. In order for sintering to be possible, it is recommended to prepare feedst...

The powder injection molding (PIM) process is a cost efficient and important net-shape manufacturing process that is not completely understood. For the application of simulation programs for the powder injection molding process, apart from suitable physical models, exact material data and in particular knowledge of the flow behavior are essential i...

Wood plastic composites (WPC) are a young generation of composites with rapidly growing usage within the plastics industry. The advantages are the availability and low price of the wood particles, the possibility of partially substituting the polymer in the mixture and sustainable use of the earth's resources. The current WPC products on the market...

The powder injection molding (PIM) process is a cost efficient and important net-shape manufacturing process that is not completely understood. For the application of simulation programs for the powder injection molding process, apart from suitable physical models, exact material data and in particular knowledge of the flow behavior are essential i...

WPC (wood plastic composites) are a young generation of composites with rapidly growing usage within the plastics industry. The advantages are the availability and low price of the wood particles, the possibility of partially substituting the polymer in the mixture and sustainable use of the earth's resources. The current WPC products on the market...

Powder injection moulding (PIM) is a multi-stage process to manufacture metallic or ceramic complex, functional parts in large quantities and with high material requirements. The flow in PIM filling process is a complicated non-isothermal problem with viscoelasticity effects and instabilities. The exact description of the whole process of the flow...

Fused filament fabrication (FFF) is one of the most commonly used polymer-based additive manufacturing techniques. FFF could be used to shape parts with PIM feedstocks instead of injection moulding and after debinding and sintering obtain solid parts with complex geometry. Currently used PIM feedstocks do not necessarily meet the requirements of th...

The technology of slit-die rheometry came into practice in the early 1960s. This technique enables engineers to measure the pressure drop very precisely along the slit die. Furthermore, slit-die rheometry widens up the measurable shear rate range and it is possible to characterize rheological properties of complicated materials such as wall slippin...

Fused Filament Fabrication (FFF) could replace injection molding as the shaping step in a process similar to powder injection molding (PIM). Herein after shaping by using a highly-filled polymer the part is debound and sintered to obtain a solid part of metal or ceramic. New feedstock materials have been developed that can be printed using conventi...

The viscosity of feedstock materials is directly related to its processability during injection molding; therefore, being able to predict the viscosity of feedstock materials based on the individual properties of their components can greatly facilitate the formulation of these materials to tailor properties to improve their processability. Many emp...

Thermoplastic Fused Filament Fabrication (FFF) is one widely used additive manufacturing processes in the world. The main reasons of its popularity and use have been its reliability, safe and simple fabrication process, low cost, and the availability of a variety of building materials. It is possible to produce metallic parts shaped by FFF through...

Powder injection moulding (PIM) process is well established for production of small precision components with both metal and ceramic powders. In comparison to unfilled polymers, the PIMfeedstocks are highly filled multiphase systems, whose flow behaviour is very sensitive to composition of binder and powder loading. Furthermore, the rheology of hig...

Rheology is a key factor for the production of high quality PIM parts, characterization of feedstocks themselves and reliable results of numerical simulation of the PIM process. Rotational rheometry is among the common techniques for characterising the flow properties of thermoplastic materials. In comparison to thermoplastics the PIM feedstocks ha...

This paper demonstrates the importance of the careful selection of the input material data for the calculation of the flow behavior of wood polypropylene composites. To this goal, the rheological data of un-dried samples were measured, utilizing a commercial high pressure capillary rheometer equipped with slit dies of different gap heights. The dat...

The influence of the rheological behaviour of PP based wood plastic composites (WPC) has been investigated in this research by means of a high pressure capillary rheometer incorporating dies having different geometries. The rheological experiments were performed using slit and round dies. The influence of moisture content on the flow properties of...

The evaluation of the effectiveness of reinforcement of polymers and polymer nanocomposites(PNCs), in particular the improvement of Young's modulus, is made by performing standardized tensile tests. Structural and morphological characterizations typically are investigated using expensive techniques like transmission electron microscopy (TEM), X- ra...

The rheological behaviour of feedstocks for powder injection moulding (PIM) strongly influences the final properties of the products and is the most critical parameter in the injection moulding process. PIM-feedstocks are highly filled multiphase systems, whose flow behaviour is very sensitive to composition of binder and powder loading. Therefore...

Incorporation of different fillers in a polymer matrix can improve various physical and mechanical properties of polymers. Layered silicates, used as nanofillers, are one of the most emphasized research topics in polymer engineering and science in the last decades. The influence of different layered silicates on the tribological properties of Polya...

The accurate knowledge of flow behavior of feedstocks is of great importance for computer simulation and optimization of the powder injection process. The feedstocks for powder injection molding are highly filled polymer compounds. The particles are in close proximity with one another. A yield point was often observed at low shear rates as an indi...

Optimal performance of feedstocks for powder injection moulding (PIM) and in further consequence the PIM part’s quality in all production stages are highly dependent on the use of an adequate binder formulation. The PIM binder systems are multiple-component systems that contain different phases due to the different requirements for the feedstock. V...

The use of polypropylene (PP)-layered silicate nanocomposite has attracted great interest in the polymer industry over the last years. On one hand, PP is widely used in many fields of applications because of good performance and cost. On the other hand, the major advantage of layered silicate nanofiller in the polymer matrix is the small amount of...

The accurate knowledge of the flow behavior of feedstocks is of great importance for computer simulation and optimization of the powder injection process. The feedstocks for powder injection molding are highly filled polymer compounds. The particles are in close proximity with one another. A yield point was often observed at low shear rates as an i...

Layered silicates, used as nanofillers, are one of the most emphasized research topics in polymer engineering and science in the last decades. Nevertheless to achieve their great potential of enhancement a homogenous dispersion of the nanofiller in the polymer matrix is essential. The achievable material improvement is in great extend depending on...

The aim of this study was to determine the influence of exfoliated silicate layers on the thermal conductivity of polypropylene nanocomposites. The correlation of thermal conductivity with the degree of exfoliation is examined and compared to common mineral fillers like talcum. The results clearly show that not only the filler content but also the...

Wood Plastic Composites (WPC) are one of the rapidly growing markets within the plastic industry. These composites find a wide range of applications, especially for flooring and in other decorative and technical fields. Initially the WPC were processed using extrusion technique. Advances in the WPC compounds paved the way for injection molding of W...

A special injection molding machine rheometer which allows processors and developers to establish this data themselves under realistic conditions is discussed. Besides a standard injection molding machine with a clamping force of 1,300 kN, the new rheometer has a special rheological injection mold, a data acquisition system and easy-to-use rheologi...

To shorten the development time for injection moulded parts, process simulations in different developing steps aswell as quick and accurate measurements of rheological data even for the increasing variety of special compounds are necessary. For simulation of thin wall injection moulding accurate viscosity data measured at shear rates up to 800.000...

Nowadays PIM is an advanced technology for the production of complex shaped metal or ceramic parts. There is a high pressure on PIM to optimise the process. Two prerequisites for this optimisation are a better understanding of the feedstock, especially for quality control, and an improved simulation of the injection moulding process for PIM. For go...

The extrusion of wood composites based on thermosetting resins is a new application in the field of wood plastic composites. To enable the extrusion of wood thermosetting compounds, it is necessary to know their reactivity and rheology well beforehand, to prevent the system curing inside the extruder. This study shows the different techniques that...

Microsystems engineering is a rapidly-growing sector in which plastics, in particular, are being used to an ever-increasing extent. It is, however, a sector which places special requirements on the production and calculation processes employed. This paper presents possible optimizations of fill simulation software to consider the special boundary c...

Rheology is a key factor for the production of high quality parts and the characterization of feedstocks themselves. Many different measuring procedures are available for measuring the rheology characteristics of polymers and feedstocks. A lot of knowledge from the characterization of plastics can be found in the literature. Feedstocks have their o...

In this work the influence of three different stabiliser systems on the stress rupture behaviour of high density polyethylene (PE-HD) pipes under constant internal pressure was examined at 60 and 80°C with special consideration of the quasi-brittle failure by growth of a single crack in the failure regime preceding the global chemical degradation o...

The shortening of the product development time, through the rapid preparation of prototypes, models and pre-serial parts becomes even more important today, to resist the market competition. By means of Rapid Prototyping procedure, prototypes are produced directly from CAD data, without models and tools, in a very short time, by the use of automatic...

Normally the developing costs are decisive for the price of a new product. New products have to be developed faster, at lower costs and better adjusted to the specific demands of the client. Nowadays it is crucial for the success of a company to be as fast as possible in developing new products and in supplying different sorts of prototypes and sam...