Papers by Agnieszka Meljon
Materials, 2020
In this article, the effect of the addition of halloysite nanotube (HNT) on the mechanical and th... more In this article, the effect of the addition of halloysite nanotube (HNT) on the mechanical and thermal stability of polypropylene (PP) and PP/kenaf fiber biocomposites has been investigated. Different volume contents of HNTs ranging from 1 to 10 vol.% were melt mixed with PP and PP/kenaf fibers. The volume content of kenaf fibers was kept constant at 30%. The morphology of HNTs within the PP matrix has been studied via scanning electron microscopy (SEM). The morphological results revealed that HNT was uniformly dispersed in the PP matrix already at a low concentration of 1 and 2 vol.%. The mechanical properties of the manufactured nanocomposites and hybrid biocomposites such as Young’s modulus, tensile strength, elongation at break, flexural modulus, flexural strength, and notched Izod strength have been measured. The results show that Young’s modulus and strengths have been improved along with the addition of low content of HNTs. Moreover, the gain of notched Izod impact strength o...
Polymer Degradation and Stability, 2014
The present work focuses on the processability and degradation control during injection moulding ... more The present work focuses on the processability and degradation control during injection moulding of two different polylactide grades after chain extension achieved using epoxidized and maleated chain extenders. In the first part of the contribution, the influence of chain extension and the resultant change in the viscosity on the processing parameters, such as injection pressure, melt temperature, or flowability, will be discussed. For this purpose, besides a normalized MFI test, a special investigation methodology, which included a flow-spiral test and the measurement of injection pressure, was employed for online observations. In regards of the flow behaviour, it was confirmed that the different functional groups of the used chain extenders play a dominant role in counteracting the degradation of polylactide. The second part deals with the mechanical performance of modified PLA. It was shown that the chain extension reaction leads to chain branching, and, thus, the crack stopping mechanism is influenced positively. As a consequence, the polymer toughness was affected and the mechanical behaviour improved.
Polymer Bulletin, 2014
The presented contribution deals with the material properties of chainextended polylactide. In th... more The presented contribution deals with the material properties of chainextended polylactide. In the course of this study, two different functional additives were used, namely an epoxidized and a maleated styrene-acrylic copolymer. Both additives were compounded together with polylactide using a conventional twinscrew extruder, and were then injection moulded to standardized testing specimens. The main focus of the investigation is on structural changes as well as the mechanical performance, e.g. crack propagation and arresting mechanisms that are affected by reactive chain extension. The first section of the experimental part consists of results regarding modifications achieved on the macromolecular level. Based on size exclusion chromatography and DSC-OIT experiments, different structural changes and their influence on the material behaviour are presented. Subsequently, a comprehensive analysis of the quasi-static tests and the impact strength of notched and unnotched specimens was performed, and correlated with the following fatigue experiments. A discussion concerning morphological aspects and finally a correlation to the fracture surface topography after fatigue test completes the experimental part.
Journal of Applied Polymer Science, 2013
The primary objective of this study was the investigation of thermo-mechanical behavior of cellul... more The primary objective of this study was the investigation of thermo-mechanical behavior of cellulosic fiber reinforced polylactid (PLA) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biopolymers. Both PLA and PHBV were processed with 30 wt % of cellulosic fibers; moreover, to improve the processability and mechanical performance, PHBV was previously blended with 30% by weight poly(butylene adipate-co-butylene terephthalate) (PBAT). Secondary target was the comparison of the obtained results to natural fiber reinforced polypropylene (PP) composites reinforced with exact the same fibers and processed by using identical techniques. For validation the thermo-mechanical properties, a dynamic mechanical thermal analysis (DMTA) was applied. Storage modulus (E 0), loss modulus (E 00), and loss factor (tan d) were determined. The DMTA results indicate decreased polymer chain motion with resulting improvement of stiffness expressed by the storage modulus. Finally, the effectiveness of fiber on the moduli was investigated. The C coefficient differs in dependence on fiber type, use of coupling agent, and the reference temperature in glassy state.
Composites Part A Applied Science and Manufacturing
This paper presents the research on hybrid thermoplastic biocomposites reinforced with a combinat... more This paper presents the research on hybrid thermoplastic biocomposites reinforced with a combination of short man-made cellulose fibres and softwood flour. The introduced short fibre composites are meant to be processed with injection moulding and may be an alternative to glass-fibre reinforced thermoplastics on account of their comparable specific strengths. The occurring positive hybrid effect enables to substitute up to half the weight of short fibre cellulose reinforcement with softwood flour without a significant reduction of material flexural strength. The flexural modulus of investigated hybrid biocomposites remained approximately at the same level, while impact strength was reduced with increasing softwood flour content. The proposed hybridisation leads to establishing biocomposites of suitable performance with competitive density, price and recycling possibilities in comparison to standard glass fibre reinforced counterparts. Moreover, the application of biobased polymers l...
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Papers by Agnieszka Meljon