The effect of hybrid carbon fillers or properties of polyester composites

Altay, Lutfiye/0000-0003-4946-3615WOS: 000509386300017In this study, synthetic graphite and graphene were used as thermally conductive fillers for polyester-based composites. Orthophthalic polyester resin, methyl ethyl ketone peroxide and cobalt octoate were used as the polymer matrix, catalyst and accelerator, respectively. Hybrid carbon (C) fillers at different weight fractions (up to 45 wt.%) were added into the polymer matrix by using an ultrasonic mixer. Composite test specimens were prepared by using the doctor blade thin-film fabrication method. the in-plane and through-plane thermal conductivity values of the composites were determined by using a Xenon Flash instrument. Furthermore, the change in the morphological structure of the carbon-filled composites was studied in detail by scanning electron microscopy. Mechanical properties were studied by performing tensile tests, and the electrical conductivity of composites was measured using an LCR meter. Significant enhancement of the thermal conductivity by way of hybrid carbon filler incorporation was obtained for polyester-based composites

First and second law analyses of wastewater cooled condenser for a refrigeration system

###EgeUn###In this study, a vapour compression refrigeration (VCR) system with a wastewater (WW) cooled condenser at a temperature range of 27-29 degrees C was designed. The cooling capacity of the system using R134a as the refrigerant was 1.09 kW. The condenser consisted of a coaxial heat exchanger with a capacity of 1 kW. This paper dealt with energy and exergy analyses of the VCR system using WW, as a heat sink. Experiments were performed in order to evaluate the energetic and exergetic performances of the wastewater-cooled condenser (WWC) and the overall system. The convective heat transfer coefficient of WW and refrigerant in the condenser, overall heat transfer coefficient of the WWC, total amount of heat removed by WW, amount of cooling effect, coefficient of performance (COP), exergy destruction rate, and second law efficiencies of the WWC and VCR system were calculated under different WW temperatures and flowrates. Increasing volumetric flowrate of WW from 200 L/h to 400 L/h caused 4.4% improvement in COP, 12.0% reduction in exergy destruction, and 10.3% increase in exergy efficiency

A parametric study of a renewable energy based multigeneration system using PEM for hydrogen production with and without once-through MSF desalination

The importance of renewable energy compared to fossil fuels is increasing due to growing energy demand and environmental challenges. Multi-generation systems use one or more energy sources and produce several useful outputs. The present study aims at investigating and comparing solar energy based multi-generation systems with and without once -through MSF desalination unit from the thermodynamic point of view. Firstly, hydrogen, electricity, and hot water for space heating and domestic usage are produced using the system, which consists of a parabolic trough collector, an organic Rankine cycle (ORC) and a PEM electrolyzer and heat exchanger as sub-systems. The performance of the entire system is evaluated from the energetic and exergetic points of view. Various parameters affecting hydrogen production rate and efficiency values are also investigated with the thermodynamic model implemented in the Engineering Equation Solver (EES) package. The system can produce hydrogen at a mass flow rate of 20.39 kg/day. The results of the study show that the energy and exergy efficiency values of the ORC are calculated to be 16.80% and 40% while those for the overall system are determined to be 78% and 25.50%, respectively. Secondly, once-through MSF desalination unit is integrated to the system between ORC evaporator and heat exchanger producing domestic hot water in the solar cycle in order not to affect hydrogen production rate while thermodynamic values are compared. Fresh water production capacity of the system is calculated to be at a volumetric flow rate of 5.74 m(3)/day with 10 stages. (C) 2022 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC

Enhanced in-plane and through-plane thermal conductivity and mechanical properties of polyamide 4.6 composites loaded with hybrid carbon fiber, synthetic graphite and graphene

Polyamide 4.6 has excellent properties, such as high temperature resistance, crystallinity, fatigue resistance, melting temperature, excellent creep resistance, toughness, and good wear properties, but low thermal conductivity values. For this reason, its use in thermal applications has been limited. In this study, its use in thermal applications can be increased by increasing its thermal conductivity with carbon-based fillers and reinforcements added to the PA46 structure. The aim of this study is to examine the carbon fiber (CF), synthetic graphite (SG) and graphene nanoplatelet (G) loading on the mechanical, thermal, physical, and electrical properties of polyamide 4.6, which are produced using co- rotating twin-screw extrusion. Tensile and flexural strength of polyamide 4.6 increased with the addition of CF at all weight fractions. The highest electrical conductivity value was measured as 4.01 S/cm in PA46-20CF-20SG-3G composite material. The highest in-plane thermal conductivity achieved in this study at 20 wt% CF, 20 wt% synthetic graphite, and 5 wt% graphene loading was 20.43 W/mK. However, the highest through-plane thermal conductivity value was obtained to be 4.19 W/mK at 20 wt% CF. Graphene and synthetic graphite are more efficient to increase the in-plane thermal conductivity, while CF is more efficient to increase the through-plane thermal conductivity.scientific and technological research council of Turkey (TUBITAK) [117M088]The scientific and technological research council of Turkey (TUBITAK), Grant/Award Number: Project No: 117M08

Hybrid carbon filled thermoplastic composites: synergistic effect of synthetic graphite and graphene nanoplatelets on thermal and mechanical properties of polyamide 4.6

In comparison with conventional polyamides, polyamide 4.6 is known as one of the high-temperature polyamides due to polymer chain constituents which also enhances its dimensional stability, creep resistance, and chemical resistance. The effect of hybrid synthetic graphite and graphene nanoplatelets fillers on thermal conductivity of polyamide 4.6 based composites was investigated in this study. Synthetic graphite and graphene nanoplatelets filled polyamide 4.6 based composites were fabricated using a twin-screw extruder. The variations on electrical, mechanical, thermal, and morphological properties were also examined. The highest in-plane and through-plane thermal conductivity values were obtained for hybrid 40 wt.% synthetic graphite and 5 wt.% graphene nanoplatelets filled composites as 21.65 and 4.04 W/mK, respectively. It was reported that the usage of hybrid carbon fillers in polyamide 4.6 leads to better thermal conductivity value..Scientific and Technological Research Council of Turkey; Turkiye Bilimsel ve Teknolojik Arastirma Kurumu [117M088]The authors are grateful for the funding from the Scientific and Technological Research Council of Turkey; Turkiye Bilimsel ve Teknolojik Arastirma Kurumu [Project no: 117M088]

Carbon Nanotube-, Boron Nitride-, and Graphite-Filled Polyketone Composites for Thermal Energy Management

In order to improve the thermal conductivity of 30 wt % synthetic graphite (SG)-filled polyketones (POKs), conductive fillers such as multiwall carbon nanotubes (CNTs) and hexagonal boron nitride (BN) were used in this study. Individual and synergistic effects of CNTs and BN on 30 wt % synthetic graphite-filled POK on thermal conductivity were investigated. 1, 2, and 3 wt % CNT loading enhanced the in-plane and through-plane thermal conductivities of POK-30SG by 42, 82, and 124% and 42, 94, and 273%, respectively. 1, 2, and 3 wt % BN loadings enhanced the in-plane thermal conductivity of POK-30SG by 25, 69, and 107% and through-plane thermal conductivity of POK-30SG by 92, 135, and 325%. It was observed that while CNT shows more efficient in-plane thermal conductivity than BN, BN shows more efficient through-plane thermal conductivity. The electrical conductivity value of POK-30SG-1.5BN-1.5CNT was obtained to be 1.0 × 10-5 S/cm, the value of which is higher than that of POK-30SG-1CNT and lower than that of POK-30SG-2CNT. While BN loading led to a higher heat deflection temperature (HDT) than CNT loading, the hybrid fillers of BNT and CNT led to the highest HDT value. Moreover, BN loading led to higher flexural strength and Izod-notched impact strength values than CNT loading

The effect of hybrid thermal fillers on thermal conductivity of carbon fiber reinforced polybutylene terephthalate composites

AbstractThe use of functional polymeric composites with superior thermal properties, capable of replacing conventional polymers, has increased in recent years, particularly in the electrical‐electronics sector where thermal management is crucial. Carbon fiber (CF) polymer–matrix structural composites have relatively high in‐plane thermal conductivity but low through‐plane conductivity. In order to further enhance the through‐plane and in‐plane conductivity of CF‐reinforced polybutylene terephthalate (PBT) composite, a hybrid loading approach was employed, incorporating synthetic graphite (SG), boron nitride (hBN), aluminium nitride (AlN) and graphene (G) in composite formulations. It was found that the in‐plane conductivity of PBT‐20CF‐20SG‐3G and the through‐plane conductivity of PBT‐20CF‐20SG‐3AlN are 69% and 25% higher, respectively, than those of PBT‐40CF. However, the mechanical properties of hybrid composites exhibit lower values compared to those of CF‐reinforced PBT composites. The tensile strength value of PBT‐40CF is about 33% and 57% higher than those of PBT‐20CF‐20SG‐3G and PBT‐20CF‐20SG‐3AlN. Moreover, the flexural strength of PBT‐40CF is about 48% and 38% higher than those of PBT‐20CF‐20SG‐3G and PBT‐20CF‐20SG‐3AlN, respectively. The density value of PBT‐40CF is lower than that of the composites of PBT‐20CF‐20SG. From TGA it was observed that the thermal stability of PBT‐40CF is comparable to that of the composites PBT‐20CF‐20SG. From the conducted study, it can be proposed that the hybrid combination of SG, hBN, AlN and G can be utilized to achieve higher thermal conductivity values, instead of relying solely on CF in the composites. © 2024 The Authors. Polymer International published by John Wiley &amp; Sons Ltd on behalf of Society of Industrial Chemistry.</jats:p

Improving the flame retardancy properties of PLA/PC blends

Polylactic acid/Polycarbonate (PLA/PC) blend was prepared via twin screw extruder by taking the bio-based content as much as possible and the better mechanical, thermal, and impact properties into consideration. Flame retardant (FR) performance of the PLA/PC blend was improved by using the mixture of ammonium polyphosphate, triphenyl phosphate, and zinc borate. FR properties of PLA/PC blend was evaluated according to the UL 94 test standard. The variations in tensile and flexural strength, and Izod-notched impact strength values were determined. In order to reduce the total amount of flame retardant additive, instead of using a mixture of TPP and APP (weight ratio of 2/1) at 21 wt% weight fraction, 1 wt% Zinc borate together with 18 wt% TPP-APP mixture was used and obtained V0 rating for the thickness of 1.5 mm. It was reported that weight fraction of flame retardant additives (APP and TPP) was successfully reduced by using a mixture of APP, TPP and ZnB without degrading the mechanical properties such as tensile and flexural strengths. Using less total FR additive weight (19 wt%) led to 15 and 24% higher tensile and flexural strength values, respectively, compared to higher FR additive weight (21 wt%)

Improving thermal conductivity of polybutylene terephthalate composites with hybrid synthetic graphite and carbon fiber

Polybutylene terephthalate (PBT) is a semi-crystalline engineering thermoplastic polyester. PBT offers rapid molding cycles, high heat resistant, crystallinity, fatigue resistance, strength and rigidity, excellent electrical properties, creep resistance, reproducible mold shrinkage and chemical resistance. In this study, PBT was loaded with synthetic graphite and carbon fiber at different weight fractions (10-40 wt.%). PBT-based composites were fabricated by the melt mixing process by using a co-rotating twin screw extruder then thermal, mechanical and morphological properties of filled PBT composites was investigated. Weight fraction of carbon fiber (up to 30 wt.%) increases the tensile strength and flexural strength of PBT, but synthetic graphite loading decreases the tensile strength and flexural strength of PBT. The highest in-plane and through-plane thermal conductivity values were obtained as 9.24 for 40 wt.% synthetic graphite filled composite and 3.41 W/mK for 40 wt.% carbon fiber reinforced composite, respectively. Carbon fiber was found to be more effective in increasing the through-plane thermal conductivities than synthetic graphite.Ege University Research Projects Coordination [18-MUH-027]The author(s) received funding from Ege University Research Projects Coordination (Project no: 18-MUH-027)