The 12th Global Conference on Polymer and Composite Materials (PCM 2025)

Abstract: Since the patents expired a few years ago, the application of 3D printing has been developing at a highly dynamic pace. By using thermoplastics as the printing material, functional parts can be produced with various properties such as strength, flexibility and heat resistance. However, it is important to note that FFF has its limitations, such as limited accuracy and surface quality. An additional challenge is the limited strength and stiffness of printed parts compared to traditional manufacturing methods. This applies in particular to the mechanical properties perpendicular to the direction of printing, which are often not at the level of injection-molded components. In addition, the quality of the components depends on the component geometry, i.e. the properties vary greatly over the component volume. As plastics are inferior to metallic materials in terms of their mechanical properties, 3D-printed components are often only suitable as demonstration objects. They cannot even be used in semi-structural applications.
Reinforcement with fibers, known from composite material technology, can provide a remedy. Nowadays, glass, carbon, aramid, or even natural fibers are combined with polymer matrix materials for this purpose. In combination with 3D printing, new possibilities open up here, as the fiber orientation and thus the mechanical properties can be specifically influenced by the choice of deposition paths, i.e. the fiber orientation can be specifically adapted to the load path.
The talk will describe the opportunities and challenges in the manufacturing of thermoplastic materials, in particular fiber-reinforced composites, using fused filament fabrication. In this process, components are manufactured by depositing a continuously extruded molten strand along pre-planned paths. The component is therefore not subjected to the same process conditions throughout its volume, particularly during cooling, crystallization, or solidification. Rather, the local deformation and solidification processes during strand deposition, comparable to welding, lead to local gradients in morphology and ultimately to anisotropy of properties. Consequently, the properties of the component
transverse to the strand deposition direction are ultimately determined by the quality of the weld between the strands (and layers), which is usually a flaw. Overall, the aim is to exploit the material
properties of fiber-reinforced thermoplastics in the fiber direction fully, but on the other hand, this must not be at the expense of transverse strength, i.e. perpendicular to the fiber direction; a challenge that can be overcome with suitable process control. In addition to classic fiber-reinforced plastics, materialadequate process control is applied to fully recyclable plastic fiber-reinforced plastics. This allows direction-dependent (orthotropic) properties to be specifically adjusted in the component, thus enabling the material- and energy-efficient use of materials modelled on nature.

Biography: Professor Alois K. Schlarb currently serves as Senior Research Professor at the RheinlandPfälzische Technische Universität (RPTU), is a member of the State Research Center OPTIMAS at RPTU, and a visiting professor at Qingdao University of Science and Technology (QUST), PR China.
Alois K. Schlarb studied mechanical engineering at the University of Kaiserslautern, specializing in production engineering and company organization. After his graduation in 1984 he relocated to the University of Kassel, working as a scientific assistant to Prof. Dr.-Ing. Dr. e.h. Ehrenstein. He was awarded a doctorate in 1989 for his thesis on polymer processing. From 1988 until 1989 he was also head engineer at the university’s Institut fuer Werkstofftechnik (Institute of Materials Technology). In the following 13 years Professor Schlarb held different positions in the industry, e.g. the polymer laboratory of BASF SE as material scientist and project manager researching composites, last as Vice President and head of marketing, research and development with B. Braun Medical AG, Switzerland. In November 2002 Alois Schlarb was appointed to a full professorship for "Composite Materials" at the Technische Universität Kaiserslautern (now RPTU Kaiserslautern-Landau) and held this position until March 31, 2022. From 2002 to 2008 he served in parallel as Chief Executive Officer of the Institut für Verbundwerkstoffe GmbH (Institute of Composite Materials). Since 2018 Alois Schlarb also holds a visiting professorship at Qingdao University of Science and Technology, Qingdao, PR China.
Professor Schlarb served as Spokesman of the Scientific Alliance of Polymer Technology (WAK) from 2009 - 2015 and as President of the Society for the Advancement of Materials and Processing Engineering SAMPE Deutschland e.V. from 2003 - 2015. He is on the editorial board or scientific advisory board of several journals and has more than 150 publications in peer-reviewed journals. He is also the editor/author/co-author of several books and book chapters. The focus of his research activities is on process-structure-property-relations and tribology of polymer-based hybrid materials.