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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 production of samples with a defined surface roughness is indispensable. The aim of this study is to analyze the impact of various mold insert roughnesses combined with the influences of particle size, filler-, and compatibilizer content on impression quality. An unfilled high density polyethylene was chosen as a reference for the impression quality investigations, while fillers with significantly different particle sizes and a compatibilizer were used to produce proprietary compounds. Injection molded parts were manufactured utilizing mold inserts with three different line roughness values. To support the obtained results, a multivariate analysis of variance, a simulation of the filling phase as well as a rheological material characterization were conducted. The results revealed that (i) the impression quality can be independent of the applied insert roughness based on the filler particle size that was studied, (ii) an increasing on both filler particle size and compatibilizer content raise the sample roughness as a function of the penetration ability of the filler into the insert valleys, and (iii) with a higher insert roughness, the thermoplastic moldings generally exhibit a significantly smoother topography. An assumed correlation between part roughness and melt viscosity could not be confirmed.
Roman Christopher Kerschbaumer; Silvester Bolka; Teja Pesl; Ivica Duretek; Thomas Lucyshyn. The Relationship between a Defined Microstructure within the Mold Surface and the Corresponding Roughness on the Part: A Systematic Study on Particle Size, Filler-, and Compatibilizer Content. Polymers 2021, 13, 2757 .
AMA StyleRoman Christopher Kerschbaumer, Silvester Bolka, Teja Pesl, Ivica Duretek, Thomas Lucyshyn. The Relationship between a Defined Microstructure within the Mold Surface and the Corresponding Roughness on the Part: A Systematic Study on Particle Size, Filler-, and Compatibilizer Content. Polymers. 2021; 13 (16):2757.
Chicago/Turabian StyleRoman Christopher Kerschbaumer; Silvester Bolka; Teja Pesl; Ivica Duretek; Thomas Lucyshyn. 2021. "The Relationship between a Defined Microstructure within the Mold Surface and the Corresponding Roughness on the Part: A Systematic Study on Particle Size, Filler-, and Compatibilizer Content." Polymers 13, no. 16: 2757.
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, the selection of a suitable processing method and product application area requires appropriate material behaviour. This paper investigates these aspects for a commercial processed, mixed waste, and two different mixed polyolefin fractions. The wastes are processed at different depths (e.g., washed/not washed, sorted into polyethylene, polypropylene, polyethylene terephthalate, polystyrene/unsorted) and then either homogenised in the extruder in advance or processed heterogeneously in the compression moulding process into plates. The produced recyclates in plate form are then subjected to mechanical, thermal, and rheological characterisation. Most investigated materials could be processed with simple compression moulding. The results show that an upstream washing process improves the achievable material properties, but homogenisation does not necessarily lead to an improvement. It was also found that a higher treatment depth (recovery of plastic types) is not necessary. The investigations show that plastic waste recovery with simple treatment from mixed, contaminated wastes into at least downcycling products is possible.
Selina Möllnitz; Michael Feuchter; Ivica Duretek; Gerald Schmidt; Roland Pomberger; Renato Sarc. Processability of Different Polymer Fractions Recovered from Mixed Wastes and Determination of Material Properties for Recycling. Polymers 2021, 13, 457 .
AMA StyleSelina Möllnitz, Michael Feuchter, Ivica Duretek, Gerald Schmidt, Roland Pomberger, Renato Sarc. Processability of Different Polymer Fractions Recovered from Mixed Wastes and Determination of Material Properties for Recycling. Polymers. 2021; 13 (3):457.
Chicago/Turabian StyleSelina Möllnitz; Michael Feuchter; Ivica Duretek; Gerald Schmidt; Roland Pomberger; Renato Sarc. 2021. "Processability of Different Polymer Fractions Recovered from Mixed Wastes and Determination of Material Properties for Recycling." Polymers 13, no. 3: 457.
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. The present work highlights the design of high-Tg epoxy-anhydride vitrimers that comprise an efficient stress relaxation at elevated temperature. Networks are prepared by thermally curing aminoglycidyl monomers with glutaric anhydride in different stoichiometric ratios. The tertiary amine groups present in the structure of the aminoglycidyl derivatives not only accelerate the curing reaction but also catalyse the transesterification reaction above Tv, as shown in stress relaxation measurements. The topology rearrangements render the networks recyclable, which is demonstrated by reprocessing a grinded powder of the cured materials in a hot press. The epoxy-anhydride vitrimers are characterised by a high Tg (up to 140 °C) and an adequate storage modulus at 25 °C (~2.5 GPa), which makes them interesting candidates for structural applications operating at high service temperature.
Michael Giebler; Clemens Sperling; Simon Kaiser; Ivica Duretek; Sandra Schlögl. Epoxy-Anhydride Vitrimers from Aminoglycidyl Resins with High Glass Transition Temperature and Efficient Stress Relaxation. Polymers 2020, 12, 1148 .
AMA StyleMichael Giebler, Clemens Sperling, Simon Kaiser, Ivica Duretek, Sandra Schlögl. Epoxy-Anhydride Vitrimers from Aminoglycidyl Resins with High Glass Transition Temperature and Efficient Stress Relaxation. Polymers. 2020; 12 (5):1148.
Chicago/Turabian StyleMichael Giebler; Clemens Sperling; Simon Kaiser; Ivica Duretek; Sandra Schlögl. 2020. "Epoxy-Anhydride Vitrimers from Aminoglycidyl Resins with High Glass Transition Temperature and Efficient Stress Relaxation." Polymers 12, no. 5: 1148.
Christian Kukla; Ivica Duretek; Joamin Gonzalez-Gutierrez; Clemens Holzer. Rheology of Highly Filled Polymers. Polymer Rheology 2018, 1 .
AMA StyleChristian Kukla, Ivica Duretek, Joamin Gonzalez-Gutierrez, Clemens Holzer. Rheology of Highly Filled Polymers. Polymer Rheology. 2018; ():1.
Chicago/Turabian StyleChristian Kukla; Ivica Duretek; Joamin Gonzalez-Gutierrez; Clemens Holzer. 2018. "Rheology of Highly Filled Polymers." Polymer Rheology , no. : 1.
I Duretek; C Holzer. Material flow data for numerical simulation of powder injection molding. Journal of Physics: Conference Series 2017, 790, 12007 .
AMA StyleI Duretek, C Holzer. Material flow data for numerical simulation of powder injection molding. Journal of Physics: Conference Series. 2017; 790 ():12007.
Chicago/Turabian StyleI Duretek; C Holzer. 2017. "Material flow data for numerical simulation of powder injection molding." Journal of Physics: Conference Series 790, no. : 12007.
I Duretek; T Lucyshyn; C Holzer. Filling behaviour of wood plastic composites. Journal of Physics: Conference Series 2017, 790, 12006 .
AMA StyleI Duretek, T Lucyshyn, C Holzer. Filling behaviour of wood plastic composites. Journal of Physics: Conference Series. 2017; 790 ():12006.
Chicago/Turabian StyleI Duretek; T Lucyshyn; C Holzer. 2017. "Filling behaviour of wood plastic composites." Journal of Physics: Conference Series 790, no. : 12006.
Christian Kukla; Ivica Duretek; Joamin Gonzalez-Gutierrez; Clemens Holzer. Rheology of PIM feedstocks. Metal Powder Report 2017, 72, 39 -44.
AMA StyleChristian Kukla, Ivica Duretek, Joamin Gonzalez-Gutierrez, Clemens Holzer. Rheology of PIM feedstocks. Metal Powder Report. 2017; 72 (1):39-44.
Chicago/Turabian StyleChristian Kukla; Ivica Duretek; Joamin Gonzalez-Gutierrez; Clemens Holzer. 2017. "Rheology of PIM feedstocks." Metal Powder Report 72, no. 1: 39-44.
Ivica Duretek; Thomas Lucyshyn; Clemens Holzer. Filling Behavior of Wood Plastic Composites. Journal of Civil Engineering and Architecture 2016, 10, 1 .
AMA StyleIvica Duretek, Thomas Lucyshyn, Clemens Holzer. Filling Behavior of Wood Plastic Composites. Journal of Civil Engineering and Architecture. 2016; 10 (11):1.
Chicago/Turabian StyleIvica Duretek; Thomas Lucyshyn; Clemens Holzer. 2016. "Filling Behavior of Wood Plastic Composites." Journal of Civil Engineering and Architecture 10, no. 11: 1.
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 empirical and semi-empirical models are available in the literature that can be used to predict the viscosity of polymeric blends and concentrated suspensions as a function of their formulation; these models can partly be used also for metal injection molding binders and feedstock materials. Among all available models, we made a narrow selection and used only simple models that do not require knowledge of molecular weight or density and have parameters with physical background. In this paper, we investigated the applicability of several of these models for two types of feedstock materials each one with different binder composition and powder loading. For each material, an optimal model was found, but each model was different; therefore, there is not a universal model that fits both materials investigated, which puts under question the underlying physical meaning of these models.
Joamin Gonzalez-Gutierrez; Ivica Duretek; Christian Kukla; Andreja Poljšak; Marko Bek; Igor Emri; Clemens Holzer. Models to Predict the Viscosity of Metal Injection Molding Feedstock Materials as Function of Their Formulation. Metals 2016, 6, 129 .
AMA StyleJoamin Gonzalez-Gutierrez, Ivica Duretek, Christian Kukla, Andreja Poljšak, Marko Bek, Igor Emri, Clemens Holzer. Models to Predict the Viscosity of Metal Injection Molding Feedstock Materials as Function of Their Formulation. Metals. 2016; 6 (6):129.
Chicago/Turabian StyleJoamin Gonzalez-Gutierrez; Ivica Duretek; Christian Kukla; Andreja Poljšak; Marko Bek; Igor Emri; Clemens Holzer. 2016. "Models to Predict the Viscosity of Metal Injection Molding Feedstock Materials as Function of Their Formulation." Metals 6, no. 6: 129.
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 is very difficult. The existence of a yield stress on PIM-feedstock depends on particle interactions within the polymer matrix. Further factors, like powder loading and dispersion during the measurements, are influencing the rheological characterisation of PIM-feedstocks. Additionally, inertial and gravitational effects can have an influence for systems with a very low viscous matrix. Quantifying yield stress, however, must be done carefully because the value obtained depends on the analytical technique used. Knowing the flow behaviour of PIM-feedstock is necessary for successful filling simulation of PIM. In this context, the yield behaviour of a stainless steel feedstock was studied using a plate-plate controlled stress rheometer (CSS). The rheological data obtained from CSS were compared to the measurement made on a slit-die rheometer in controlled shear rate mode (CSR). Controlled stress rheology is more sensitive and provides more accurate results of yield stress than CSR.
Christian Kukla; Ivica Duretek; Clemens Holzer. Controlled shear stress method to measure yield stress of highly filled polymer melts. PROCEEDINGS OF THE REGIONAL CONFERENCE GRAZ 2015 – POLYMER PROCESSING SOCIETY PPS: Conference Papers 2016, 1779, 070006 .
AMA StyleChristian Kukla, Ivica Duretek, Clemens Holzer. Controlled shear stress method to measure yield stress of highly filled polymer melts. PROCEEDINGS OF THE REGIONAL CONFERENCE GRAZ 2015 – POLYMER PROCESSING SOCIETY PPS: Conference Papers. 2016; 1779 (1):070006.
Chicago/Turabian StyleChristian Kukla; Ivica Duretek; Clemens Holzer. 2016. "Controlled shear stress method to measure yield stress of highly filled polymer melts." PROCEEDINGS OF THE REGIONAL CONFERENCE GRAZ 2015 – POLYMER PROCESSING SOCIETY PPS: Conference Papers 1779, no. 1: 070006.
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 size and number of the main particles (specific surface) influence thermal conductivity significantly. With respect to this, the smaller the particles and the more particles are in the matrix, the higher the increase in thermal conductivity. Compared to common fillers, the increase in thermal conductivity is considerably higher with exfoliated layered silicates and directly depends on the degree of exfoliation. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers
Stephan Laske; Ivica Duretek; Andreas Witschnigg; Hannelore Mattausch; Daniel Tscharnuter; Clemens Holzer. Influence of the degree of exfoliation on the thermal conductivity of polypropylene nanocomposites. Polymer Engineering & Science 2012, 52, 1749 -1753.
AMA StyleStephan Laske, Ivica Duretek, Andreas Witschnigg, Hannelore Mattausch, Daniel Tscharnuter, Clemens Holzer. Influence of the degree of exfoliation on the thermal conductivity of polypropylene nanocomposites. Polymer Engineering & Science. 2012; 52 (8):1749-1753.
Chicago/Turabian StyleStephan Laske; Ivica Duretek; Andreas Witschnigg; Hannelore Mattausch; Daniel Tscharnuter; Clemens Holzer. 2012. "Influence of the degree of exfoliation on the thermal conductivity of polypropylene nanocomposites." Polymer Engineering & Science 52, no. 8: 1749-1753.