Zagovor diplomskega dela študenta Matije Ranzingerja
Zagovor diplomskega dela študenta Matije Ranzingerja bo potekal v ponedeljek, 20. 9. 2021 ob 13. uri v sejni sobi (2. nadstropje Fakultete za tehnologijo polimerov).
Sklep o imenovanju komisije dostopen TUKAJ.
SUMMARY
Electrically conductive polymer bio-composites
Plastics are widely used as insulating materials. Electrical conductive polymer composites have wide technological applications, such as fuel cells, electrochemical catalysts, neural probes, static charge dissipating materials, various detecting sensors, etc. [1]. Compared to other conductive materials, such as metals, plastics can be shaped into complex shapes with ease using conventional shaping processing techniques, as well as additive manufacturing techniques. The inclusion of a biologically based conductive filler into biologically based polymer materials can provide a sustainable alternative to current printed circuit boards (PCBs), for example, thus helping in electronic waste management [2]. In the current bachelor’s thesis, we prepared and characterized electrically conductive polymer bio‑composites from PHBV (polyhydroxybutyrate‑valerate) and PP (polypropylene) in combination with carbonized Tencel fibres and carbonized wood particles. The main focus of the research was to determine the influence of fibre length and filler size, as well as the influence of carbonization temperatures and loading of fibres and fillers on electrical and mechanical properties of PHBV and PP bio‑composites. Electrical conductivity was measured both parallel and perpendicular to injection flow. Higher electrical conductivity was obtained when measurements were carried out parallel to injection flow. In general, electrical conductivity, impact strength, and HDT were higher in composites with fibres and fillers carbonized at higher temperatures. Increasing the load of carbonized cellulose fibres from 5 vol% to 20 vol% exponentially increases electrical conductivity. Increasing the load of carbonized wood particles from 5 vol% to 15 vol% only linearly increases electrical conductivity. Tensile modulus, flexural modulus, impact strength, and HDT increased with increasing fibre and filler load up to a certain point. Both injection moulding and compression moulding / hot pressing were used to prepare test specimens for electrical conductivity measurements. Parallel measured specimens exhibited superior electrical conductivity over perpendicular measured specimens. Compression moulded specimens were less electrically conductive due to unoriented and widely distributed fibres but their electrical conductivity was unaffected by the direction of measuring. Injection moulded specimens showed anisotropic electrical properties while compression moulded specimens showed isotropic electrical properties. Additionally, composites were recycled and measured for their electrical conductivity, tensile modulus, flexural modulus, and HDT which decreased after one recycling step due to fibre breakage and thermal degradation.
Key words:
Electrical conductivity, polymer bio‑composites, PHBV, PP, carbonized fibres.