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Item type:Publication, Access status: without files , Poly(trimethylene terephthalate-b-poly(trimethylene ether) glycol) copolymers: From bio-based thermoplastic elastomers to elastic fibers for apparelIntroducing the renewable poly(trimethylene ether glycol) (PO3G) as soft segments into bio-based poly(propylene terephthalate) (PTT), which is synthesized from the bio-based propylene glycol (PDO) monomer, results in thermoplastic polyester elastomers (PTT-PO3G) with superior thermomechanical properties. As the PO3G content in PTT-PO3G copolymers increased from 20 wt% to 60 wt%, the melting temperatures of these copolymers decreased from 220 to 174°C, and the tensile strength decreased from 31.7 to 4.2 MPa with the Shore hardness falling from 60 to 26 D, whereas the elongation at break showed an increase tendency from 697 % to 1074 %. Characterizations utilizing dynamic thermomechanical analysis (DMA), small angle X-ray scattering (SAXS), and atomic force microscopy (AFM) revealed the presence of microphase separations in PTT-PO3G copolymers. The strength and moisture regain of PTT-PO3G-20 elastic fibers fabricated via an eco-friendly melt spinning technique reach 1.42 cN/dtex and 1.52 %, which are 58 % and 407 % higher than those of traditional wet-spun Spandex® fibers, respectively. Surprisedly, the resilience of PTT-PO3G-20 fibers exceeded 96 % at an elongation of 20 %, demonstrating its promising potential as a sustainable alternative to Spandex® fibers in textile applications. The excellent thermodynamic properties indicate that the bio-based PTT-PO3G copolymers have great potential to replace traditional petroleum-based elastomers for promoting the sustainable and low-carbon global development.Publicationtype: Journal Article73 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Stretchable semiconducting triblock copolymer blends : exploring the impact of block size(2024-03-06); ; 27 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Morphological influence of carbon nanofillers on the piezoresistive response of carbon nanoparticle/epoxy composites under mechanical load(Elsevier, 2016-10-18); ; ; ; In this study, we investigate the piezoresistive response of carbon black and multi walled carbon nanotube/epoxy composites films and bulk specimens. The morphology of the nanocomposites has been influenced by variation of particle geometry, aspect ratio, filler content and AC-field induced alignment of the particles. This allows to understand the influencing parameters so the electrical resistance change (ERC) of the material becomes adjustable. All nanocomposites show a reproducible characteristic ERC vs. strain under quasi-static unidirectional tension, with a resistance increase, a maximum and a subsequent resistance decrease at high strains. Due to the occurring maximum in ERC two resistance values correlate to one strain level. This ambiguity of ERC is unfavourable for sensing purposes. Higher aspect ratios and filler contents shift the maximum to a lower strain level, while the sensitivity is reduced. Alignment of particles leads to a shift of the maximum to a higher strain level, a linear ERC and a gauge factor of about six, but reduces the conductivity. In the composites films the alignment of particles in load direction enhances the strain sensing capabilities.Publicationtype: Journal Article69 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Preparation and characterization of graphite nano-platelet (GNP)/epoxy nano-composite : mechanical, electrical and thermal propertiesEpoxy based polymer nano-composite was prepared by dispersing graphite nano-platelets (GNPs) using two different techniques: three-roll mill (3RM) and sonication combined with high speed shear mixing (Soni-hsm). The influence of addition of GNPs on the electrical and thermal conductivity, fracture toughness and storage modulus of the nano-composite was investigated. The GNP/epoxy prepared by 3RM technique showed a maximum electrical conductivity of 1.8 × 10-03 S/m for 1.0 wt% which is 3 orders of magnitude higher than those prepared by Soni-hsm. The percentage of increase in thermal conductivity was only 11% for 1.0 wt% and 14% for 2.0 wt% filler loading. Dynamic mechanical analysis results showed 16% increase in storage modulus for 0.5 wt%, although the Tg did not show any significant increase. Single edge notch bending (SENB) fracture toughens (KIC) measurements were carried out for different weight percentage of the filler content. The toughening effect of GNP was most significant at 1.0 wt% loading, where a 43% increase in KIC was observed. Among the two different dispersion techniques, 3RM process gives the optimum dispersion where both electrical and mechanical properties are better.Publicationtype: Journal Article58 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Water transport in epoxy/MWCNT composites(Elsevier, 2013-05-29); ; ; ; Moisture and water uptake of epoxy/multi-wall carbon nanotube (MWCNT) composites was studied in a wide range of atmosphere relative humidity and temperatures. Addition of up to 1 wt.% of MWCNTs into the neat epoxy resulted to the twofold decrease of the diffusivity, while the levels of moisture/water uptake remained unchanged. The positive effect on the reduction of the diffusion coefficient diminishes with the increase of temperature. Differences in the water transport properties and plasticization ability of the neat polymer and its nanocomposites are explained by the free volume considerations and the polymer-water interactions, which are verified by the results of thermomechanical analysis. Water uptake by the nanocomposites resulted to a lower decrease of the storage modulus than that of the neat epoxy.Publicationtype: Journal Article74 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Combined electrical and rheological properties of shear induced multiwall carbon nanotube agglomerates in epoxy suspensions(Elsevier, 2011-08-12); ; ; ; In this work the rheological and electrical properties of semi-dilute carbon nanotube (CNT)-epoxy suspensions have been discussed. The suspensions are produced using two types of industrially available CNTs (Nanocyl 3150 and 7000) and using two different dispersion techniques, namely 3-roll milling and sonication. In-situ optical microscopic analysis and electrical conductivity measurements have been conducted. It is shown that despite using CNTs with similar aspect ratios, the dispersability of the raw material and the time stability of the suspensions are quite different. Additionally, viscosity measurements are used to evaluate the initial dispersion quality and time stability.Publicationtype: Journal Article25