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Foam injection molding is a processing technology to produce foamed plastic parts in serials production, attaining an increasing interest and use in industry. However, the applications are limited due to insufficient knowledge of processing and mechanical properties, limited use of light-weight potential as well restricted surface qualities. All these drawbacks are associated with the cellular structure. The structure characteristics like skin layer thickness, cell size, density and uniformity are developed during procedure. Thus, controlling the cell formation process is the key to work against the restrictions and optimize mechanical properties.

Schaumspritzgießen

Schaumstoffe

Spritzgießsimulation

Schäumen / Reaktive Verarbeitung

Industrie 4.0 für die Kunststoffverarbeitung

Controlling cellular structure in thermoplastic foam injection molding – influence of processing and mold technologies

Due to the low thermal conductivity of the polymer matrix, fiber reinforced polymers exhibit a low thermal conductivity compared to metals. By increasing the thermal conductivity and thereby decreasing thermal stresses in the part, an enhancement of its lifetime can be expected.

Beschichten von Kunststoffen

Kohlenstofffasern / -matten

Faserverbundwerkstoffe

Wärmeleitfähigkeitsmessung

Epoxy Based Carbon Fiber Reinforced Polymers with Enhanced Thermal Conductivity – Structure and Properties

Additive manufacturing, such as the selective laser sintering (SLS), provides the possibility to manufacture structures as 3D-MIDs tool free. The first three-dimensional circuit carriers are already manufactured by selective laser sintering. An established method is the LPKF-LDSprototyping process. Different from conventional 3D-MIDs this process requires an ensuing coating of the additive manufactured circuit carrier with a metal compound containing substance to enable the direct structuring by laser. Commercially available materials for injection molded 3D-MIDs already contain certain additives for laser direct structuring, that can be activated by laser. Thus, the demand for functional powder compounds for the selective laser sintering process to design three-dimensional circuit carriers is mandatory.

Structures and properties of selective laser sintered polyamide- and polyamide-copper-systems for applications in three-dimensional circuit carriers

Expandable polystyrene (EPS, coll. “Styropor”, “Unicell”, “Styrofoam”) is one of the most used foams. It accounts for one quarter of the current foam production in terms of volume. EPS has a multi-scale morphology since EPS parts consist of many fused foamed beads. The foamed beads themselves contain cells, which are formed of walls and struts as well as the cell gas. In this frame, a variation in bead size causes a significant change of surface area, which needs to be moulded, whereas the variation in cell size leads to an altered micro-morphology (cell walls and struts). However, the effect of the multi-scale morphology on the properties has never been studied in a comprehensive manner to the knowledge of the author. Hence, the aim of the work is the establishment of structure-property relationships as well as the clarification of their fundamental mechanisms for the purpose to be able to tailor the structure for a specific application. Thus, further material and cost savings could be possible. EPS and a bead foam made from a blend of polystyrene and polyethylene were studied regarding the effects of cell size, bead size and density on the mechanical and thermal behaviour. Furthermore, the distribution of polymer within a single bead was controlled by the introduction of a solid skin around the beads.

Structure-property relationships of polystyrene-based bead foams

Epoxy-carbon fiber prepregs have been used increasingly by civil aerospace industry to manufacture the structural composite parts due to their excellent mechanical, thermo-mechanical and thermal properties at the cured state. Although carbon fibers are electrically conductive, due to the insulating nature of the epoxy matrix, epoxy-carbon fiber prepreg laminates mostly act as a semiconductor in the through-thickness direction. Nowadays, an enhanced through-thickness electrical conductivity is as well desired for modern composite applications, where a certain level of electrostatic dissipation, electromagnetic shielding or an enhanced lightning strike resistance is necessary.

Towards electrically conductive and interleaf-toughened carbon black-epoxy-carbon fiber laminates with enhanced lightning strike resistance

In cooperation with the Wissenschaftlicher Arbeitskreis Kunststofftechnik (WAK), we provide free access to current dissertations in the field of plastics technology.

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FACHARTIKEL_2021, FACHARTIKEL_2020, FACHARTIKEL_2019, FACHARTIKEL_2018, FACHARTIKEL_2017, INTERVIEWARTIKEL_2021, INTERVIEWARTIKEL_2020, INTERVIEWARTIKEL_2019

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