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SCHEME 2. Synthesis of polyimide.
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In this study, a new diamine N-[2-(1H-indol-3-yl)ethyl]-3,5-diaminobenzamide (IEDAB) was synthesized using tryptamine as starting material and characterized by FT-IR, ¹H-NMR, ¹³C-NMR, and mass spectroscopy. Then, it was polymerized with 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA) via thermal imidization to produce polyimide (PI). A se...
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A new chiral diamine l-methyl 2-(3,5-diaminobenzamido)-3-phenylpropanoate (MABPP) was synthesized using l-phenylalanine (essential amino acid) as the starting material. The structure of the synthesized diamine was supported by FT-IR, ¹H, and ¹³C-NMR and mass spectral techniques. The diamine was polymerized with 3,3′,4,4′-benzophenone tetracarboxyli...
Citations
... 3,4 In general, adding conductive nanofillers to a polymer matrix is a versatile approach to improve its thermal conductivity. 5,6 Researchers have attempted to improve the thermal conductivity of PI or PEI by adding various pure or hybrid nanofillers, such as carbon nanofibers, 7 aluminum nitride (AlN), 8 low-melting-point SnBi 17 Cu 0.5 , 9 hybrid carbon nanotube (CNT)/PI-grafted multiwall CNT/AlN, 10 PI-coated hexagonal boron nitride (h-BN), 11,12 iron oxide-doped h-BN, 12 expanded graphite, 13 short fiber/expanded graphite, 14 alkyl-or phenyl-aminated graphene oxide (GO), 15,16 graphite nanoplatelets, 17 and graphene nanoplatelets (GNPs) 18 to the polymer matrix. Among these, GNPs and their derivatives or hybrids are versatile nanofillers that have also been used to improve the thermal conductivity of other polymer matrices. ...
In this work, an I‐optimal response surface model was used to systematically investigate the effects of graphene (Gr) content (Factor A; 0–10 wt%), temperature (Factor B; 0–200°C), and Gr layer structure (Factor C; monolayer versus five‐layer) on the thermal conductivities of PEI/Gr nanocomposites, which were determined using reverse non‐equilibrium molecular dynamics (RNEMD) simulation with the Müller‐Plathe algorithm. Based on a reduced quadratic model that was fit to the data, the effect of Factor A on thermal conductivity was found to be more pronounced for the PEI/Gr nanocomposite with the five‐layer Gr structure. Moreover, Factor B had expectedly the largest effect on thermal conductivity, followed by Factor C. However, these two factors were involved in significant interactions with Factor A. Based on numerical optimizations, the predicted thermal conductivities of the PEI/Gr nanocomposites varied from 0.057 (minimum) to 0.174 W m ⁻¹ K ⁻¹ (maximum). Overall, the maximum thermal conductivity of the PEI/Gr nanocomposite may be obtained at any given temperature in the range of 0–200°C by the addition of multi‐layer Gr (a cheaper alternative to monolayer Gr) at a content of 10 wt%. For example, the addition of 10 wt% five‐layer Gr to PEI at room temperature (25°) results yields an increase in its thermal conductivity of about 30%. Also, going from 0 to 100°C, an increase of about 76% is predicted for the thermal conductivity of the PEI/Gr nanocomposite containing 10 wt% five‐layer Gr. The results of this study shed light on the interactions between the three investigated factors.
Highlights
Thermal conductivities of polyetherimide/graphene (PEI/Gr) nanocomposites simulated.
Graphene (Gr) content, temperature, and Gr layer structure affected the thermal behavior.
Response surface methodology (RSM) aided in the identification of factorial interactions.
Numerical optimization of the thermal conductivities enabled by a predictive model.
... 21e1272) phase respectively. The diffraction peak ( confirms the presence of GO (JCPDS file no: 41e1487) in the corresponding sample (Balaji et al., 2017;Dsilva Winfred Rufuss et al., 2017b;Sadhasivam and Rigana, 2018). The XRD showed that TiO 2 and CuO were crystalline whereas GO was amorphous. ...
... The XRD results of GO obtained here are consistent with those of other researchers (Shi et al., 2012;Sohail et al., 2017). It is therefore concluded that the amorphous nature of GO is as expected and not defective or detrimental to the thermal properties of NPCM in low temperature energy storage applications such as solar stills (Balaji et al., 2017;Dsilva Winfred Rufuss et al., 2017b;Jebasingh, 2016;Mehrali et al., 2013;Shi et al., 2012;Yu et al., 2010). ...
This paper investigates the effects of nanoparticle-enhanced phase change material (NPCM) on solar still operation and performance. Technical and economic aspects were considered, to show an advance on earlier works using virgin phase-change materials (PCM). Three types of nanoparticle (TiO2, CuO and GO) were impregnated individually at 0.3 weight% in paraffin to form NPCM-1, NPCM-2 and NPCM-3 respectively. Experiments were conducted with four solar stills (SS) each of 0.5 m² area using respectively paraffin (SSPCM), paraffin-TiO2 (SSNPCM-1), paraffin-CuO (SSNPCM-2) and paraffin-GO (SSNPCM-3). There was observed an increase in thermal conductivity and a reduction in melting and solidification temperatures, with NPCM compared to PCM. The effects of NPCM on water temperature, storage temperature, hourly and annual productivity were determined. SSPCM, SSNPCM-1, SSNPCM-2 and SSNPCM-3 yielded 3.92, 4.94, 5.28 and 3.66 l/m²/day respectively, corresponding to 26 and 35% increases in productivity of SSNPCM-1 and 2 respectively over SSPCM. Economic analysis showed cost per liter (CPL) of water of $0.035, $0.028, $0.026 and $0.13 for SSPCM, SSNPCM-1, 2 and 3 respectively. Considering the advantages in productivity and CPL, SSNPCM-2 can be recommended as the best solar still compared to SSPCM, SSNPCM-1 and 3, providing clean water at less than half the cost of bottled water in India.
Polyimide/graphene (PI/G) composite fibers containing p-phenylenediamine ( p-PDA), 3,3′,4,4′-Biphenyl tetracarboxylic diandhydride (BPDA) and graphene (G) were prepared by wet spinning and thermal imidization. The mechanical properties, thermal stability, orientation factor and morphology of PI/G composite fibers were characterized and studied. Within the scope of the study, the tensile strength and tensile modulus of the fibers increased first and then decreased with the increase of the graphene content. Moreover, the glass transition temperature and thermal decomposition temperature of the PI/G composite fibers increased with the increased of the graphene content. X-ray diffraction (XRD) showed that the degree of orientation of the of prepared fibers increase firstly and then decrease with the content of graphene increasing. SEM indicated that graphene was dispersed evenly in the PI/G composite fibers and graphene had satisfactory compatibility with PI matrix.
Antibacterial nanocomposite films of poly(butylene adipate‐co‐terephthalate) (PBAT) incorporated with different weight percentage of octakis(3‐chloropropyl)octasilsesquioxane (chloropropyl functionalized POSS [Cl‐fn‐POSS]) nanofiller were prepared. The mechanical, thermal, morphological, barrier, and antimicrobial properties were examined. The mechanical properties of the nanocomposite films were enhanced by the addition of Cl‐fn‐POSS nanofiller. An optimum filler loading of 3 wt% is identified to be best suited for maximum enhancement in tensile strength (24 MPa for 3 wt% filled PBAT vs 11 MPa for neat PBAT) while a 1 wt% filler loading was adequate to double the tensile strength. The barrier properties (WVTR and oxygen transmission rate) of PBAT was improved by the presence of Cl‐fn‐POSS. A volume of 3 wt% filler loading results in 50% reduction of water permeation and 10% reduction in oxygen transmission. The thermogravimetric analyses of the nanocomposites indicated that the filler enabled the enhancement of thermal stability of PBAT. The nanocomposite films revealed antimicrobial activity with this activity increasing with increasing filler content. PBAT is compostable under suitable conditions and with a low weight percentage of filler that is largely made of silicon dioxide these nanocomposite films can find application as biodegradable food packaging material given their flexibility.
The modified graphene oxide (GO) with different specific functional groups were prepared and introduced into rigid polyurethane foam (PUF). It was proved that NCO groups were bonded on the surface of GO, which could participate into the polyurethane foaming reaction and dramatically improve the interactions between the filler and matrix. It was found that the cell morphology and the mechanical properties of the PUFs could be effectively improved by adding an appropriate amount of modified GO. The isocyanate‐modified GO could form a stable chemical bond with the matrix, which was more beneficial to improve the mechanical properties. The thermal conductivity slightly increased with the increase of modified GO, however the values were still low enough for thermal insulation applications. Thus, these nanocomposite foams with improved structure and properties would find wide applications in the thermal insulation areas.
The polyimide/kaolinite nanocomposite films based on the functionalized kaolinite were prepared and studied systematically. The natural kaolinite was modified by the indirect coupling to obtain the reactive kaolinite, which could be dispersed uniformly in the polymer matrix. It was found that the reactive kaolinite had effect on the crystal structure and increased the molecular weight of the polyimide. The significant improvement in the water resistance, thermal stability and mechanical property of polyimide/kaolinite nanocomposite was achieved with the addition of the reactive kaolinite. The tensile strength of polyimide/kaolinite nanocomposite increased by 40.6% compared to pure polyimide, Young's modulus of polyimide/kaolinite nanocomposite was increased to 1.95 GPa from 1.56 GPa. Finally, the mechanism to prepare the polyimide/kaolinite nanocomposite was proposed. POLYM. ENG. SCI., 2019. © 2019 Society of Plastics Engineers POLYM. ENG. SCI., 2019.
