Epoxy Resin

Epoxy rosin is a type of thermosetting polymer, commerci whole in ally available in different forms, has a immense range of application in aerospace, coating, electric automobile automobile insulation and marine application ascribable to its outstanding performances, easy handling and minuscule cost 1-5. Epoxy graduate(prenominal) intragroup deform, unannealed texture, inferior impact resistance, sick creep resistance and poor wet resistance, limited its application in some otherwise industrial areas 6.So, the paste glue was mixed with polymers7, clays, coat 8, carbon nanotube 9, graphene10, and graphene oxide11 to overcome its limitations. Graphene oxide (GO) is a graphite derivative that produced by dint of oxidation of graphite using various methods. Graphene oxide is a 2D sheet with type O useful at the go forth (hydroxyl, carbonyl, and epoxide) and (carboxyl) at its ring 12,13. Graphene oxide is a promising physical as polymer reinforcement, referable to its senior high school mechanistic properties14, first-class caloric stability15, and good insulation properties 16.Moreover, graphene oxide high open area, high expectation proportion, elegant sheet flexibility, reactivity sites, and good spreading in most common dissolvent favored its use a obscures material for polymeric material. The Graphene oxide tends to improve the mechanical properties, caloric stability, insulator, and insulator properties of the various commercial paste resin. However, Graphene oxide sheets tend to aggregate either by Van der Waals force or ?-? stacking fundamental interaction, which would return the improvement effects of graphene sheets in paste glue glue glue glue resin ground substance 17. Therefore, graphene oxide was special either through covalent trammel nets or by ?-? interaction to reduce these aggregation phenomena and raise paste glue resin properties.For instance, Wan et al improved paste glue glue tensile aptitude and mod ulus by 75% and 15% through mixing glue with graphene oxide limited with DGEBA (diglycidyl ether of bisphenol-A) 18.Also, Liu et al raise paste glass temperature and tensile forte by 26oC and 31% using grafted graphene oxide 5. Sharmila et al prepared Graphene oxide modified with iron oxide nanoparticles, they epoxy composites tapern improvements in the tensile, impact, and chap strength 19. Fluorinated polymer is polymer lay off carbon- atomic number 9 bonds and they has been apply in many home(prenominal) and industrial application collectible thither excellent thermal stability, anti-chemical corrosion, weathering resistance, high dielectric conduction, and low bob up energy 20-22. However, the high market price of the fluoropolymers and poor miscibility in epoxy resin restricted their applications 23. thermal stability, roughness, and corrosion resistance were improved for epoxy resin modified with a fluorinated polymer 24-27. The degree Fahrenheit atoms cut ba ck the crosslinking density of the epoxy resin and fluoropolymer, trim the mechanical properties of the epoxy 28. The join of the fluorinated polymer into carbon theme material much(prenominal) as carbon nanotube, fluorinated graphene, and fluorinated graphite whitethorn combine the excellent properties of carbon base material and atomic number 9 groups properties.The miscibility was improved with enhancement of the mechanical properties, thermal stability, surface properties, and electric properties. Yang and coworkers grafted fluorinated polymer on reduced graphene oxide coated with dopamine. The modified graphene showed excellent sprinkle in the ferroelectric polymer matrix with good high dielectric everlasting and low dielectric red ink 29.Que et al modified epoxy resin (DGEBA) with trifluoromethyl containing polyimide structures. Compared with polished epoxy, they found that the modified epoxy shown break down thermal stability with 18 to 55 % char yield at 800 0C, pissing finish up be given (94.9105.0), higher toughness, and set about water arrangement absorption (0.470.95 %). The tensile shear of modified epoxy was let down than the slap-up epoxy, the atomic number 9 groups reduced epoxy surface energy which further reduced the shackle strength compared with unmodified epoxy 7. In this work, graphene oxide was modified with Hexadecafluoro (1, 10) de sack upediol through one-step reaction. modify graphene oxide was mixed with epoxy resin in various fill.Then, the mechanical properties, thermal stability, water contact angle water inhalation, and basic corrosion resistance were examined for epoxy composites.Results and parole The surface hold upalization of GO was corroborate by FTIR, XRD, XPS,Raman spectrometry, and TGA. Fig. (1) shows the FTIR spectrum of GO and GOFO.For GO typical heights were discovered at 3390 cm-1 ( stretchability shudder of C-OH), 1041 cm-1 (stretching vib symmetryn of C-O), 1374 cm-1 (deformatio n vib symmetryn of C-OH), 1261 cm-1 and 877 cm-1 (stretching vibration of C-O-C), and 1734cm-1 (stretching vibration of C=O).The diadem at 1619 cm-1 is attributed to the skeletal vibration of the graphitic of GO 30. After reaction with FO smart rosinesss appeared.The peaks at 1178 cm-1 (stretching vibration of C-F) 31, at 2966 cm-1 (bending stretching of C-H), and at 1441 cm-1 (stretching vibration of C-H) from the perfluoro compound.The peak at 1080 cm-1 was related to stretching vibration of ester bond C-O-C. These results indicated that FO was successfully grafted onto GO surface.The XRD precedents of graphite, GO, and GOFO was shown in Fig. (2) and the interlayer distance was metrical using Bragg equation. indigenous graphite is shown a typical peak at 26.410 with an interlayer spacing of 0.337 nm 32. This peak shifted to 11.020 (corresponding to an interlayer space of 0.802 nm) afterward graphite was oxidate to GO, that was cod to the formation of atomic number 8-cont aining functional groups on a graphite oxide surface and water molecules trapped betwixt the layers 33.The functionalization of GO with FO shifted the peak from 11.020 to 10.080 (corresponding to an interlayer space of 0.676nm), suggested that GO was modified with FO. Another panoptic diffraction peak was ascertained at 22.760, which suggests the formation of few layers of reduced graphite oxide.To further study the structural differences in the midst of graphite, GO, and GOFO, the graphitic watch glass surface was mensural using Sheerer equation and the number of layers was calculated based on crystal size. Graphite had a large crystal size of 21.28nm with 63-64 graphene layers. After oxidation to GO, the crystal size lessen to 10.92nm and the number of layers decreased to 10-11 graphene layers.The crystal size of GOFO was 3.78nm with 5 -6 layers of the modified graphene sheet. In order to study the exfoliation of GOFO into the epoxy matrix, the XRD patterns of EGOFO compos ites and dandy epoxy were inquired as shown in Fig. (3). For refined epoxy, two colossals peaks c usher ined at ?70 and ?180 were spy due to the amorphous nature of swell epoxy. alone Epoxy composites show the comparable attribute diffraction peak as neat epoxy and no diffraction peaks of GOFO at 10.080 and 22.760 were observed 34. Thats affirm that GOFO was highly exfoliated into the epoxy matrix. Although, the highly exfoliated aim of GOFO sheets in the epoxy matrix tushnot check a good public exposure was obtained in the epoxy composites 35.The thermographic compend in Fig. (4) represents the thermal stability of GO and GOFO under a nitrogen atmosphere. Graphene oxide shows 8.404% encumbrance departure between 50 0C -100 0C, due to evaporation of eternal rest water trapped between the layers. A signifi fecal mattert lean loss of 29.53% was observed between 100 0C 250 0C, thats due to guff of labile atomic number 8 functional groups to H2O, CO, and carbon dio xide 22,10.Compared to GO, GOFO was more s panel with 3.48% cargo loss was observed between 50 0C -100 0C move be appoint to evaporate of proportion water trapped between the layers, which was lower than GO. Between 100 0C 250 0C, 8.18% weight loss was found due to de bit of the reaming oxygen functional groups.Then, 12.44% weight loss was observed between 250 0C 550 0C, that mint be assigned to the decomposition of the bond between GO and perfluoro compound. In accession, compared with 48.59% weight loss at 700 0C for GO, GOFO undergoes 20.83% weight loss. The above data can be due to GO, bosses high kernel of oxygenated functional groups, while GOFO possesses low oxygenated functional groups due to functionalization by FO. The above results confirmed that GOFO was more stable than GO.Raman spectroscopy was applied to explore the structural variations between GO and GOFO. Generally, the graphitic material shows two characteristic peaks, the G peak (1575 cm?1) arises from f irst-order scattering of the E2g photon of sp2 C atoms and the D peak (1350 cm?1) from a breathing mode of ?-point photons of A1g symmetry.Also, the intensity ratio ID/IG can be utilise to evaluate the graphitization tip of the graphitic material, the lower look upon represented a high degree of graphitization 30. Fig. (5) shows Raman spectrum results of GO and GOFO. The G and D bands of GO were located at 1599.9 and 1357 cm-1 receptivity, as describe in previous reports 30,36,37. After functionalization with FO, the G band was shifted to a lower wavelength at 1589 cm-1, no obvious changes were observed for the D band. In addition, the ID/IG intensity ratio of GO increases from 0.96 to 1.062 for GOFO. The changes in the intensity ratio imply that GOFO of graphene structure was restored, which can be due to the removal of oxygen functional groups.The GO and GOFO were characterized using X-ray photoelectron spectroscopy (XPS), the results are shown in Fig. (5) and the elemental an alysis is tabulated in circuit board (1). The GO broad spectrum shows two peaks at binding energies somewhat 286.1 eV and 532.4 eV, which were assigned to C1s and O1s, respectively. The atomic composition of graphene oxide was obtained from XPS broad spectrum and revealed the presence of carbon (71.88%) and oxygen (28.12%). In cable, the GOFO broad spectrum displayed three peaks at binding energies around 286.1 eV, 532.4 eV, and 686 eV, they can be assigned to C1s, O1s, and F1s respectively. The atomic composition of GOFO obtained from the broad spectrum shown the existence of carbon (71.66%), oxygen (27.34%), and fluorine (1%). The carbon-to-oxygen ratio increase from 1.6 for GO to 2.6 for GOFO, due to functionalization with FO.The C1s XPS spectrum of GO and GOFO are shown in Fig. (6). The C1s spectra can be decomposed into four characteristic peaks C=C/C-C (non-oxygenated carbon, 284.5 eV), C-OH/C-O-C (hydroxyl, epoxy, and 286eV), C=O (carbonyl, 286.8 eV), and COOH (carboxyl, 2 88.9 eV) 38. In comparison, the decomposed C1s spectrum of GOFO shows additional peaks at 287.02eV, 290 eV, and 292 eV, assigned to -C-O- (ether bond), C-F (fluorine), and C-F2 (fluorine) respectively39. As shown in Fig. (5), compared with XPS C1s spectrum of GO (Fig. (6)), the peak intestines of C-O and C-O-C were importantly decreased, new peaks appeared. The above results indicated the attachment of FO to graphene oxide surfaces via the reaction with hydroxyl groups of FO with C-O groups on the GO surfaces 40.As shown in the SEM images of EGOFO composites, the GOFO sheets were salutary dispersed in the epoxy matrix. GOFO nano-sheets were adjoin tightly by epoxy resin, which indicates a good interfacial interaction between GOFO and the epoxy matrix. Such good interfacial bonding improves the stress move out from the epoxy matrix to the GOFO nano-sheet and thus enhanced the mechanical properties of epoxy composites.However, due to the presence of incommensurable fluorine grou ps on the GOFO, micro-voids can be observed and such voids could enhance dig initiation which leads to decrease the mechanical properties of epoxy composites41.SEM analysis of epoxy composites The SEM images of epoxy and epoxy composites at breakage site after the tensile test are shown in Fig. (7). The images were used to examine the dispersion and the compatibility of GOFO in the epoxy matrix. Fig. (7a,b) shows neat epoxy exhibited relatively smooth surface with a river-like pattern in the fracture direction, confirmed the brittle nature of epoxy 42.In contrast epoxy composites displayed rougher, fluctuant surfaces with GOFO nano-sheet pulled out of the epoxy matrix Fig. (7 c,e). Also, epoxy composites SEM images shown that GOFO nano-sheets were well dispersed in the epoxy matrix, a well interfacial interaction between the nano-sheets and epoxy composites Fig. (7 d,f). The good interfacial bonds can effectively transfer the stresses from the epoxy matrix to the GOFO nano-sheets and thus enhanced the mechanical properties of epoxy composites 41.However, several micro-voids can be observed in all epoxy composites that can be due to the presence of fluorine groups. The low compatibility between the epoxy resin and fluorine groups caused the appearances of micro-voids. Cracks can initiate easily in the micro-voids, so spread through epoxy composites reducing epoxy composites strength.Mechanical properties of epoxy composites ductile testThe tensile test was conducted to investigate the effects of GOFO on the epoxy resin performance. Fig. (8) shows the stress-strain curves of neat and epoxy composites, and the results were summarized in table (2).The tensile modulus of uncontaminated epoxy was 471 MPa and its changes to 486 MPa (increase by 3.2 % with 0.1 wt. %), 507 MPa (increased by 7.6 % with 0.3wt. %), and 530 MPa (increased by 12.52 % with 0.5 wt. %). The highest tensile modulus was 12.52% compared to neat epoxy corresponding to 0.5% GOFO fill. The inc rease in the tensile modulus was due to the good dispersion and interfacial interaction between the GOFO and epoxy matrix. Thats led to the good transfer of stress from the matrix to GOFO sheets.However, the tensile strength decreased by 18.35%, 22.15%, and 20.25% with 0.1 wt. %, 0.3 wt. %, and 0.5 wt. %. GOFO loading. The formation of micro-voids between the GOFO sheets in the epoxy matrix due to repugnance between GOFO sheet and epoxy system due to the presence of fluorine groups. burst testThe effects of GOFO loading on the fracture properties are shown in Table (2) and the stress-strain curves of fracture analysis were shown in Fig. (9). EGOFO composites shown a battened in the fracture modulus and strength to those of neat epoxy upon different loading. The fracture modulus was 1510MPa for neat epoxy.With 0.1, 0.3, and 0.5 wt. % loading of FO, the fracture modulus increased to 234017.61 MPa, 232473.5 MPa, and 245045 MPa respectively, these were 54.97, 53.84, and 62.85% respecti vely. However, for fracture strength, its behaved differently with increasing GOFO concentration.The fracture strength decreased by 13.12% with the addition of 0.1 wt.% GOFO loading and then increased to 13.61% and 16.98% with 0.3 wt.% and 0.5 wt.% GOFO loading respectively.The increase in the fracture modulus and strength can be attributed to improvement in the interfacial interaction between the GOFO and epoxy matrix. Thats allowed better load transfer from the epoxy matrix to the GOFO sheets, which increased both fracture modulus and strength.thermic stability of epoxy compositesThe Thermal stability of the GOFO nanocomposites was investigated by TGA as shown in Fig. (10) and Table (3).T10% and T50% are the temperature of warning weight loss reached 10% and 50 % respectively. Tdec is the sample decomposition temperature.All the specimens showed similar thermal degradation doings with main weight loss between 3500C to 4500C. They exhibited different weight loss during the onset decomposition stages as shown in the enlarged window. The incorporation of GOFO significantly enhanced the thermal stability of epoxy composites in different trends. Epoxy composite 0.3 wt. % GOFO loading has a higher T5%, T50%, and Tdec compared with other epoxy composites. The T5% and T50% increased by ?13 and ?150C respectively based on polished epoxy. The Tdec increased by ?13 with the same loading compared to pure epoxy.According to the literate, at that place are two factors effects on the thermal stability of polymer composites the formation of networks via covalent linkages between them and the crosslinking density 43,44. The existence of the oxygen functional groups at the edge and the surface of the GOFO, can react with the epoxy resin and increased the crosslinking of the composites. The XRD data showed that GOFO doesnt have a uniform crystal shape compared to graphite, that makes the GOFO has a poor thermal conductivity. Therefore, with good dispersion of GOFO, it wil l act as a roadblock and reduce the thermal conductivity of the epoxy composites 44.Water uptake epoxy compositesThe influences of water absorbed by the polymeric material can be significantly reduced by incorporating nano-size fillers into polymers 45,46.The water uptake of neat epoxy and its composites filled with GOFO were shown in Fig. (11). The addition of GOFO nano-fillers significantly decreased the come of water absorbed by epoxy composites. The water uptake by neat epoxy was 0.432%, which decreased to 0.317% , 0.304% , and 0.308% for epoxy composites with 0.1wt.% , 0.3wt.% , and 0.5 wt.% GOFO loading respectively. this phenomenon implied that the addition of nano-size sheet with high aspect ratio provided tortuous pathways for water molecules to enter the epoxy composites and acted as a barrier water transportation through epoxy composites 47. Another reason can be due to the hydrophobic nature of fluorine groups on GOFO, which can immobilized water molecules and prevented it from dispersal in epoxy matrix47.The hydrophobic behavior of GOFO compositesFig. (12). Shown the air/water contact angle of pure epoxy and its composites. The measurement was performed at room temperature with three repetitions for each sample.From Fig. (12), the incorporation of GOFO increased the contact angle of all epoxy composites. The contact angle increased from 68.70 o 1.73 for the pure epoxy to 83.53 o 1.13 for 0.1 wt. % GOFO, 98.65 o 2.49 for 0.3 wt. % GOFO, and 89.22 o 0.70 for 0.5 wt. % GOFO.The changes in the contact angle indicate that epoxy composites show more hydrophobic effects compared to pure epoxy 48. The GOFO tends to immigrate to the surface of epoxy, due to the low surface energy of the fluorine atoms.They altered the surface energy and increased the hydrophobicity of the epoxy surface. But, with 0.5 wt. % GOFO loading, the contact angle decreased to 89.22 o 0.70, the aggregated GOFO nano-sheet at the surface can slightly reduce the mark of the surfa ce and increased the effects of the reaming oxygenated function groups of the graphene sheet.