Electrical and Thermal Conductivity of Polylactic Acid (PLA)-Based Biocomposites by Incorporation of Nano-Graphite Fabricated with Fused Deposition Modeling (original) (raw)
Related papers
Effect of graphene content on the properties of poly(lactic acid) nanocomposites
In the current work, the influence of temperature on the exfoliation of expandable graphite (EG) and its structural properties were investigated in detail. The EG exfoliated at 750 C was subjected to sonication and further used as reinforcement material in the poly(lactic acid) (PLA) matrix to investigate the influence of “graphene” (GR) on the structural, morphological, thermal, optical, mechanical and oxygen barrier properties of PLA composites. X-ray diffraction results disclose the effect of sonication time on the dispersion ability of GR in the PLA matrix. A high resolution transmission electron microscopy image of GR demonstrates a monolayer structure of GR. Thermo-gravimetric analysis reveals that the Tonset value for the PLA composite with 0.5 wt% GR content increases by 6 C over neat PLA, when 10% weight loss is taken as a point of comparison. The increase in the thermal stability of PLA composites is also verified by an increase of activation energy (Ea) value evaluated by the Coats–Redfern method. Differential scanning calorimetry analysis confirms that GR acts as a nucleating agent that enhances the melting point of PLA composites over neat PLA. The enhancement of tensile strength (17%) and elongation at break (51%) is obtained for PLA composites over neat PLA.
Polymers
In the present study, polylactic acid (PLA) enriched with carbonaceous particles like multi-walled carbon nanotubes (MWCNTs), graphene nanoplates (GNPs) or a combination of both up 12 wt % of loading are used for producing 3D-printed specimens with fused deposition modeling (FDM) technology which are then experimentally and theoretically investigated. The goal is to propose a non-conventional filaments indicated for additive manufacturing process with improved dielectric and thermal properties, compared to the performances exhibited by the unfilled polymer. In the light of the above, a wide dielectric spectroscopy and a thermal analysis, supported by a morphological investigation, are performed. The results highlight that the introduction of 1-dimensional filler (MWCNTs) are more suitable for improving the dielectric properties of the resulting materials, due to the enhancement of the interfacial polarization and the presence of functionalized groups, whereas 2-dimensional nanoparti...
Materials, 2022
Overheating effect is a crucial issue in different fields. Thermally conductive polymer-based heat sinks, with lightweight and moldability features as well as high-performance and reliability, are promising candidates in solving such inconvenience. The present work deals with the experimental evaluation of the temperature effect on the thermophysical properties of nanocomposites made with polylactic acid (PLA) reinforced with two different weight percentages (3 and 6 wt%) of graphene nanoplatelets (GNPs). Thermal conductivity and diffusivity, as well as specific heat capacity, are measured in the temperature range between 298.15 and 373.15 K. At the lowest temperature (298.15 K), an improvement of 171% is observed for the thermal conductivity compared to the unfilled matrix due to the addition of 6 wt% of GNPs, whereas at the highest temperature (372.15 K) such enhancement is about of 155%. Some of the most important mechanical properties, mainly hardness and Young’s modulus, maximu...
Polymers
Natural fibre biopolymer composites with both fibres and matrix being derived from biomaterials are increasingly used in demanding applications, such as sensing, packaging, building, and transport, and require good electrical, thermal, and flame retardant properties. Herein, an investigation of the effectiveness of functionalising nonwoven cotton/poly(lactic acid) (PLA) fibre mats with graphene oxide nanosheets has been reported by using a facile dip-coating method followed by thermal reduction for enhancing the electric, thermal, and abrasion-resistance properties. The manufacturing processes for preparing biocomposites and introducing functionality are readily scalable. Experimental results reveal that with the addition of less than 0.5 wt% graphene nanoplatelets, the biocomposites showed significant improvements in abrasion resistance, electrical conductivity, thermal conductivity, and diffusivity. Furthermore, the composite shows excellent piezo-resistivity to act as strain sens...
Polymers and Polymer Composites
Biocomposites of poly(lactic acid) (PLA) and micrometre-sized graphite (GP) flake powder with 0–30 wt% GP contents have been prepared using extrusion moulding followed by compression moulding. The pure PLA and PLA-GP composites (PGC) have been examined by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy (RS), X-ray diffraction (XRD) technique, scanning electron microscopy (SEM), transmission electron microscopy (TEM), mechanical and micromechanical testing, differential thermal analysis (DTA) and thermogravimetric analysis (TGA). FTIR spectra confirm the physical bond formation between GP and PLA. RS distinguishes the D-band spectra of pure PLA and PGC. XRD shows a partially crystalline structure in the PLA. SEM and TEM exhibit a clear dispersion of GP particles in PLA matrix at lower loading and aggregates at higher loading. With an increase of filler content, the tensile and flexural strengths decrease, but the Young’s and tangent moduli are observed to increase ...
2021
Many research efforts have been directed towards enhancing the thermal properties of polymers, since they are classically regarded as thermal insulators. To this end, the present study focuses on the thermal investigation of poly(lactic acid) (PLA) filled with two types of carbon nanotubes (trade names: TNIMH4 and N7000), two type of graphene nanoplatelets (trade names: TNIGNP and TNGNP), or their appropriate combination. A significant increase in the thermal conductivity by 254% with respect to that of unfilled polymer was achieved in the best case by using 9 wt% TNIGNP, resulting from its favorable arrangement and the lower thermal boundary resistance between the two phases, matrix and filler. To theoretically assist the design of such advanced nanocomposites, Design of Experiments (DoE) and Response Surface Method (RSM) were employed, respectively, to obtain information on the conditioning effect of each filler loading on the thermal conductivity and to find an analytical relatio...
Impact of the Graphite Fillers on the Thermal Processing of Graphite/Poly(lactic acid) Composites
Materials
To assess the impact of graphite fillers on the thermal processing of graphite/poly(lactic acid) (PLA) composites, a series of the composite samples with different graphite of industrial grade as fillers was prepared by melt mixing. The average size of the graphite grains ranged between 100 µm and 6 µm. For comparative purposes, one of the carbon fillers was expandable graphite. Composites were examined by SEM, FTIR, and Raman spectroscopy. As revealed by thermogravimetric (TG) analyses, graphite filler slightly lowered the temperature of thermal decomposition of the PLA matrix. Differential scanning calorimetry (DSC) tests showed that the room temperature crystallinity of the polymer matrix is strongly affected by the graphite filler. The crystallinity of the composites determined from the second heating cycle reached values close to 50%, while these values are close to zero for the neat polymer. The addition of graphite to PLA caused a slight reduction in the oxidation induction t...
Thermal Conductivity of Graphite-Based Polymer Composites
Impact of Thermal Conductivity on Energy Technologies
It is well known that polymers are insulators, which limit their usage in other applications where thermal conductivity is essential for heat to be efficiently dissipated or stored. In the past, the improvement in the thermal conductivity of polym.rs with conductive fillers has been investigated by researchers. Carbon-based materials such as graphite, graphene and carbon nanotube, which feature excellent properties such as a high mechanical strength, a high thermal conductivity and a tailorable electronic configuration, have been added to different polymer matrices to enhance their thermal conductivity. Amongst others, graphite more especially expanded graphite merits special interest because of its abundant availability at a relatively low cost and lightweight when compared to other carbon allotropes. Herein, we describe the thermal conductivity of polymer/graphite composites and their applications.
Properties enhancement of polylactic acid biocomposite
Chemical engineering transactions, 2018
Natural rubber toughened by polylactic acid/graphene (PLA/NR/GR) biocomposite was prepared by two different processes known as the in-situ melt mixing process (conventional) and the integration of latex compounding masterbatch and melt mixing process. These two processes were employed to compare the state of graphene dispersion and distribution in the biocomposite. Good dispersion and distribution of nanographene is a key factor that can enhance or change the properties of the nanocomposite. The objectives of this work are to evaluate the effect of different processes and graphene content on the mechanical, and morphological of PLA/NR/GR biocomposites. The composition of PLA/NR blend was fixed at 80/20 wt% and the graphene content was varied from 0.1 - 0.4 parts per hundred (phr). The integration process produced the PLA/NR/GR nanocomposite with better mechanical properties compared with the conventional process due to a better state of GR dispersion in the nanocomposite. The tensil...
Macromolecular Symposia, 2020
Poly(lactic acid) or PLA bio-composite is prepared by filling with micro-graphite via solution blending. The micro-graphite loading is varied from 0-15 wt%. The objectives of this research are to investigate the influence of micro-graphite loading on PLA bio-composite, on the viscoelasticity and thermal stability. The viscoelasticity behavior exhibits a considerable dependence on the melt properties of the PLA/micro-graphite bio-composites on the percentage micro-graphite. The complex viscosity | *|, storage modulus (G'), and loss modulus (G″) tend to improve with increasing micro-graphite loading. Thermogravimetric analyses indicate that the micro-graphite slightly stabilizes the PLA. The decomposition reaction is shifted to a higher temperature in the range 7-9°C. This reaction leads to the loss of volatile byproducts, which occur at temperatures higher than 310°C. It means far from the melt processing conditions. The differential scanning calorimetry thermogram shows that the glass transition temperature (T g) and the melting temperature are close to that of neat PLA with changes only around 2-4°C.