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Carbon Fibers and Their Composite Materials

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Nguyễn Gia Hào

Academic year: 2023

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The statistical analysis identified the correlation between the process settings, fiber surface characteristics and the performance of the fibers during single fiber pull-out testing. An important parameter faced in all research in this domain is the role of the interface between the fiber and the resin.

Materials and Methods

For the detection of the fiber (a sudden change in force), a detection speed of 6 mm/min was used and the detection sensitivity was set to g. The force-displacement curves and the maximum force, Fmax, required to pull the fiber out of the matrix were measured.

Results

In this technique, gaseous probes are injected into a column filled with carbon fibers, which interact with various functional groups on the surface of the fibers. Wide-scan XPS spectra (Figure 3, left column) showed – with the exception of hydrogen – all elements in the surface region of the carbon fibers.

Figure 1. SEM images of all treated fibres from this study; sample 1 is the untreated sample, samples 2–7 show the same surface features and no surface defects have been detected.
Figure 1. SEM images of all treated fibres from this study; sample 1 is the untreated sample, samples 2–7 show the same surface features and no surface defects have been detected.

Discussion

Conclusions

Patents

Effects of plasma oxidation on surface and interfacial properties of carbon fiber/polycarbonate composites. Carbon. Interfacial adhesion properties of carbon fiber/polycarbonate composites using a single filament fragmentation test.

Curing Effects on Interfacial Adhesion between Recycled Carbon Fiber and Epoxy Resin Heated by

Introduction

The IFSS between the carbon fiber and epoxy resin was calculated using the following equation. When the epoxy resin reached the gelation point, the rheometer was controlled according to segment II.

Table 1. Materials for composites.
Table 1. Materials for composites.

Results and Discussion

The pre-curing of epoxy resin before gelation had no effect on the shrinkage behavior of the epoxy resin. With MW heating, the temperature of the epoxy resin on the CF interface rises rapidly.

Figure 2. Thermogravimetric (TG) curves of carbon fiber (CF) and carbon fiber-reinforced plastic (CFRP) as a function of temperature (a) and CFRP as a function of time under isothermal conditions of 500 and 600 ◦ C (b).
Figure 2. Thermogravimetric (TG) curves of carbon fiber (CF) and carbon fiber-reinforced plastic (CFRP) as a function of temperature (a) and CFRP as a function of time under isothermal conditions of 500 and 600 ◦ C (b).

Conclusions

Interfacial adhesion properties of carbon fiber/polycarbonate composites using a single filament fragmentation test. Compos. Effect of carbon nanotubes on the interfacial shear strength of t650 carbon fiber in an epoxy matrix. Compos.

A New Way of Toughening of Thermoset by Dual-Cured Thermoplastic/Thermosetting Blend

Introduction General Remarks

These are the absorbed dose (D); energy absorbed per unit mass measured in Gray (Gy), dose rate (absorbed energy per unit mass and unit time measured in Gy/s) [26], gas atmosphere and structure of the polymer to be irradiated. The KIC critical intensity factors are listed, i.e. fracture toughness for both diglycidyl ether bisphenol F (DGEBF) neat resins and DGEBF/PES blends [28, 29].

Experimental Details

EB-cured epoxy resin (80-90 kGy) containing 10% by weight polyethersulfone (PES) has a value of the elastic modulus of approx. 3.6 GPa. The epoxidation of the styrene/butadiene-based triblock copolymer was achieved by using m-chloroperoxybenzoic acid (m-CPBA) [35].

Figure 1. The chemicals used and their structures. (a) Diglycidyl ether of bisphenol A (DGEBA);
Figure 1. The chemicals used and their structures. (a) Diglycidyl ether of bisphenol A (DGEBA);

Results and discussion

The decrease in intensity of peaks corresponding to olefinic protons is related to DOE. In the case of mixtures with eKraton, the impact strength increases with the dose amount of eKraton.

Figure 3. Spectra of eKraton (top) compared with Kraton D1101 (bottom); solvent: CDCl 3
Figure 3. Spectra of eKraton (top) compared with Kraton D1101 (bottom); solvent: CDCl 3

Lignin as a Functional Green Coating on Carbon Fiber Surface to Improve Interfacial Adhesion in

Materials and Methods 1. Materials

To prepare drops from the epoxy matrix, epoxy resin and hardener were mixed in a ratio of 1:5 (v/v) according to the manufacturer's recommendations. Lignin was covalently attached to the graphitic carbon fiber surface according to Figures 1, 2 and 4. The high-resolution C1s spectrum of the non-functionalized carbon fiber surface (inset of Figure 5a) shows a broad, featureless peak attributed to localized (amorphous) and also delocalized alternative hydrocarbons [40, 41].

Compared to the O1s spectrum of the non-functionalized sample (Figure 5b Inset), the spectrum of the functionalized sample can be resolved into further components indicating surface C–O and C=O bonds [41], which have a similar contribution to that shown in the C1s spectrum (Figure 5a).

Figure 2. Reaction scheme for grafting 4-(aminomethyl)benzene functions onto the carbon fiber surface.
Figure 2. Reaction scheme for grafting 4-(aminomethyl)benzene functions onto the carbon fiber surface.

O COOH C=O

Mainly because of the heterogeneity of carbon fiber surface, it is difficult to detect functional groups on the surface [17,46]. Improvement of the interfacial strength of carbon fiber reinforced epoxy composites by green grafting of poly(oxypropylene)diamines. Effects of Bond Types of Carbon Fibers with Branched Polyethylenimine on the Interfacial Microstructure and Mechanical Properties of Carbon Fiber/Epoxy Resin Composites.Compos.

A systematic study of carbon fiber surface grafting via in situ generation of diazonium for improving interfacial shear strength in epoxy matrix composites.

Figure 6. Interfacial shear strength determined indirectly using fragmentation test. The test was performed on composites prepared using cellulose propionate as matrix and unfunctionalized carbon fiber, (a) 4-(aminomethyl)benzene functionalized carbon fiber,
Figure 6. Interfacial shear strength determined indirectly using fragmentation test. The test was performed on composites prepared using cellulose propionate as matrix and unfunctionalized carbon fiber, (a) 4-(aminomethyl)benzene functionalized carbon fiber,

Seebeck Coefficient of Thermocouples from

Nickel-Coated Carbon Fibers: Theory and Experiment

Materials and Methods 1. Material

It is clear that the result of Equation (11) is also proportional to the difference of the two Seebeck coefficients, εNi−εC. In the case of the highest utilized concentration of H2O2 in this experiment, only some small dust, sparsely distributed, is present on the surface of CF (Figure 4d). In Figure 5, the graph of the experimental data (with markers) was also presented as a comparison with the theoretical one.

Influence of the textile substrate on the heat transfer of a textile heat flow sensor.Sens.

Table 1. Characteristics of nickel-coated carbon yarn (NiCCY) [14].
Table 1. Characteristics of nickel-coated carbon yarn (NiCCY) [14].

Experimental

The optimal processing temperature and curing time for the prepreg was determined by measuring the rheological and thermal properties of the resin [16]. The shear modulus can be calculated by measuring the slope of the shear stress-strain curve. It was thought that the formability and unformability of the prepreg would be affected by the drawing depth and angle.

The blank holder and punch were positioned 2 mm from the top of the surface of the prepreg layer.

Table 1. Physical properties of the different types of prepreg.
Table 1. Physical properties of the different types of prepreg.

Results and Discussion 1. Material Properties of the Resin

Flat and smooth surfaces were obtained on the inclined wall of the square bowl after demoulding. Only shrinkage of the fiber orientation at 0◦ (left and right sides of the laminate in Figure 8b) occurred after thermoforming. This may be caused by the asymmetric shear deformations of the fabric during the thermoforming process.

The gradual increase in shear angle for the first 20 mm path of the simulation in Figure 11 described the experimental behaviors well.

Figure 3. (a) Viscosity dynamic scan; (b) Degree of cure versus time at different temperatures for the fast-cure epoxy resin.
Figure 3. (a) Viscosity dynamic scan; (b) Degree of cure versus time at different temperatures for the fast-cure epoxy resin.

A Comparison of Ethylene-Tar-Derived Isotropic Pitches Prepared by Air Blowing and Nitrogen

Results and Discussion 1. Characterization of NDP and ABP

This can be easily explained by the higher oxygen content of the ABP, as shown in Table 1. To further study the molecular structure of the NDP and the ABP, 13C-NMR was performed. Most of the aromatic carbon in NDP was Car1,3, indicating an abundant pericondensation structure in the NDP [25].

The higher tensile strength can be attributed to the uniform composition of ABP and less gas released in the carbonization process.

Table 1. Softening point (SP), pitch yield, and elemental analysis results of the air-blown pitch (ABP) and the nitrogen-distilled pitch (NDP).
Table 1. Softening point (SP), pitch yield, and elemental analysis results of the air-blown pitch (ABP) and the nitrogen-distilled pitch (NDP).

Evaluation of an FE Model for the Design of a Complex Thin-Wall CFRP Structure for

  • The CALIFA-FAIR Calorimeter: A Case Reference
  • Mechanical Tests Setup and Measurements to Obtain the Reference Data
  • Definition and Analysis of the FE Models
  • Results and Discussion for Mechanical Test Setups and FE Models
  • FE Model for the Instrument Structure
  • Conclusions

In Figure 3, there is a view of the grid pattern used for the two-part CF configuration. In the real structure, the current sensors fill the CF parts and cause the entire structure to load. Looking only at the load point on side B, the results of the two- and eight-section CF configurations can be compared (Table 3 and Table 5).

For the validation of the FE model, two mechanical rigs were mounted, one with two CF parts and the other with eight CF parts.

Figure 1. (a,b) picture and drawing of one CF-part (in mm); (c) drawing of the honeycomb CF-structure.
Figure 1. (a,b) picture and drawing of one CF-part (in mm); (c) drawing of the honeycomb CF-structure.

Optimal Design of Sandwich Composite Cradle for Computed Tomography Instrument by Analyzing the

  • Fundamental Properties of Materials
  • X-ray Transmission of Materials 1. Configuration of Test Device
  • Design of CT Cradle
  • Manufacturing Process and Performance Evaluation of CT Cradle 1. Manufacturing Process of Cradle
  • Conclusions

Finally, the sandwich cradle was assembled and hardened to ensure uniform X-ray transmission to the X-ray measurement area of ​​the sandwich cradle. The configuration of the X-ray transfer performance evaluation device is shown in Figure 1. The relationship between the measured value of the actual sandwich structure and the transfer rate calculated using Equation (1) for the total face thickness and Equation (2) for the core thickness was analyzed in Table 5.

Measurements of the X-ray transmission rate of individual materials show that the X-ray transmission performance is significantly affected by the density and thickness of the materials.

Table 1. Specifications of applied fiber.
Table 1. Specifications of applied fiber.

Fatigue Behavior of Concrete Beam with Prestressed Near-Surface Mounted CFRP Reinforcement

According to the Strength and Developed Length

Experimental Program 1. Test Variables

For this purpose, the specimens are designated as shown in Figure 1 with respect to the concrete strength and the developed length of the CFRP tendon selected as test variables. For the prestressed NSMR, grooves must be cut for anchoring the FRP tendon, which can be embedded in concrete. Consequently, the pulling force of 100 kN was equivalent to approx. 42% of the tendon strength applied in the manufacture of the specimens.

The tension force was measured by means of the load cell attached to the hydraulic cylinder and verified using the sensors placed on the FRP tendon.

Table 1. Test variables and designation of specimens.
Table 1. Test variables and designation of specimens.

Test Rsults

Figure 9 depicts the variation of the mid-span stress of the beam at the top load according to the accumulation of the fatigue load. Figure 17 shows the ductility of the specimens in relation to the developed length of the CFRP tendon. This study examined the strengthening performance of prestressed NSMR under fatigue load accumulation.

The measured stress at the center of the CFRP tendon also showed similar trend according to the accumulation of fatigue cycles.

Figure 5. Variation of mid-span deflection during fatigue loading at upper load limit.
Figure 5. Variation of mid-span deflection during fatigue loading at upper load limit.

Influence of Abrasive Waterjet Parameters on the Cutting and Drilling of CFRP/UNS A97075 and UNS

Results and Discussion 1. Straight Cuts Evaluation

On the other hand, Figure 9c,d shows the examined spot on striations observed by SOM microscopy and EDS analysis results, respectively. This difference is due to the lower energy of the water beam when it collides with aluminum. The data shows that the AMFR parameter has a greater impact on aluminum, especially when it is at the exit of the material.

On the other hand, the bottom material has lower roughness values ​​in region 4 due to the protection of the top material.

Figure 6. SOM image of CFRP profile. Test 2. Water pressure (WP) = 2500 bar, traverse feed rating (TFR) = 15 mm/min and abrasive mass flow rate (AMFR) = 340 gr/min for: (a) UNS A97075/CFRP;
Figure 6. SOM image of CFRP profile. Test 2. Water pressure (WP) = 2500 bar, traverse feed rating (TFR) = 15 mm/min and abrasive mass flow rate (AMFR) = 340 gr/min for: (a) UNS A97075/CFRP;

From Design to Manufacture of a Carbon Fiber Monocoque for a Three-Wheeler Vehicle Prototype

Materials and Methods 1. Geometry Design

This solution provides not only a significantly stiffer rear assembly and a shorter wheelbase, but also greater design freedom for the external shape of the vehicle's tail. The position of the driver was adjusted so that the handlebar passed under the knees, while the wheels were level with the hip. Reduced wheelbase of the vehicle helps to reduce the front of the car and also the volume of the wheel arches, which improves aerodynamic drag (a lower wheelbase means a lower steering angle is needed to run the same curve).

The temperature gap between the two solutions justified the presence of the NACA duct to improve the propulsion's efficiency.

Results 1. FEM Results

The same approach was used to design the front end and tail of the vehicle with lower loads. For example, interlaminar cohesion was strictly dependent on the absence of air bubbles absorbed during the manufacture of the laminate. The authors tried to reduce the weight of the vehicle as much as possible and highlighted the main steps.

The carbon fiber monocoque design delivered excellent results in terms of mass and stiffness.

Hình ảnh

Table 3. Complete overview of process settings and associated test results.
Table 7. Adhesion energy and interfacial tension for LEXAN™ HF1110 polycarbonate.
Figure 5. Optical photographs showing the morphology of EP/eKraton (90/10 wt.%): (a) Before and (b) after curing.
Figure 6. TEM images of EP/eKraton blends (90/10 wt.%) with different irradiation doses
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