Influence of interfacial reaction on interfacial performance of carbon fiber and polyarylacetylene resin composites

The influence of interfacial reaction on interfacial performance of carbon fiber/polyarylacetylene resin composites was studied. For this purpose, vinyltrimethoxysilane containing a double bond was grafted onto the carbon fiber surface to react with the triple bond of polyarylacetylene resin. The reaction between polyarylacetylene resin and vinyltrimethoxysilane was proved by reference to the model reaction between phenylacetylene and vinyltrimethoxysilane. Surface chemical analysis by XPS, surface energy determination from the dynamic contact angle, and the interfacial adhesion in composites was evaluated by interfacial shear strength test as well. It was found that vinyltrimethoxysilane, which can react with polyarylacetylene resin, had been grafted onto the carbon fiber surface. Furthermore, because the reaction between polyarylacetylene resin and vinyltrimethoxysilane took place at the interface, the interfacial adhesion in composites was significantly increased, and the improvement of interfacial adhesion was all attributed to the interfacial reaction.     

Interfacial Properties of Phosphate Glass Fiber/Poly(caprolactone) System Measured Using the Single Fiber Fragmentation Test

Phosphate glass fiber of the composition 20Na₂O–24MgO–16CaO–40P₂O₅ was produced using an in-house fiber drawing rig. The interfacial properties of the phosphate glass fiber/poly(caprolactone) (PCL) system were measured using the single fiber fragmentation test (SFFT). The system was calibrated using E-glass fibers and polypropylene system. This gave an interfacial shear strength (IFSS) of 4.1 MPa, which agrees well with other published data. The IFSS for the unsized (as drawn) phosphate glass fiber/PCL system was found to be 1.75 MPa. Fibers treated with 3-aminopropyl-triethoxy silane (APS) showed an IFSS of 3.82 MPa. X-ray photoelectron spectroscopic (XPS) analysis of unsized and silane sized fibers established the presence of silane on the fiber surface. Degradation tests of the silane treated fiber/PCL samples were carried out in deionised water at 37°C and it was found that the IFSS values decreased over time. Four others silanes were also investigated but APS gave the highest IFSS values.     

Preparation of Encapsulated Polymer Adhesion Beads and Adhesion with Porous Fibers

Adhesion beads of 10–130 μm, prepared by suspension polymerization, were encapsulated by melamine–formaldehyde. The capsule-type adhesives prepared consist of core and shell structure where the core region is sticky and viscous and the shell region consists of a hard shell at room temperature. The air permeable pads are made by hot pressing the mixture of capsule-type adhesives and porous materials including charcoal chips and Camellia sinensis fibers, which have a porous structure. The interfacial adhesion between polymer adhesion bead and porous fibers after processing shows a good porous sheet structure, which can penetrate air.     

Reinforcement effects of multiwall carbon nanotubes in elastomeric matrices: Comparison with other types of fillers

Mechanical and electrical properties of composites based on butyl rubber and multiwall carbon nanotubes (MWNTs) are investigated. Gradual increases in elastic moduli are observed with the filler content. It was found that the degree of strain affects the electrical resistivity. Finally, the level of reinforcement imparted to a rubbery matrix by carbon nanotubes is compared with that provided by other types of fillers such as carbon black, clay fibers or layered silicates.     

Interfacial adhesion of cellulose fiber and natural fiber filled polypropylene compounds and their effects on rheological and mechanical properties

Rayon fiber (RN) and pine wood fiber (PW) filled polypropylene (PP) compounds, PP/RN (90/05 and 75/25 wt%) and PP/PW (90/05, 75/25 and 50/50 wt%), are investigated for their interfacial adhesion, rheological properties, morphology, nucleation and mechanical properties. The interfacial adhesion of the RN-filled PP compounds is better than that of the PW ones. As the concentration of the RN and the PW particles is increased, the dynamic viscosity, the crystallization temperature, and the tensile modulus are increased; however, the tensile strain is decreased. The viscosity of the RN-filled compounds is higher than that of the PW ones at the same loadings. Significant differences are found in the elongation yield test. As the concentration of the particles is increased, the elongation yield stress of the RN compounds is increased. Elongation yield stress of the PW compounds is decreased and more spherulites are locally developed on the RN surface than the PW surface. The interfacial adhesion of the RN surface with PP is better than that of the PW surface. The elimination of extractives on the PW surface improves the mechanical property of the PW/PP compounds; however, it reduces processability of the PW/PP compounds.     

Interfacial evaluation of single Ramie and Kenaf fiber/epoxy resin composites using micromechanical test and nondestructive acoustic emission

Interfacial shear strength (IFSS) of environmentally friendly natural fiber reinforced polymer composites plays a very important role in controlling their overall mechanical performance. The IFSS of various Ramie and Kenaf fiber/epoxy composites was evaluated using the combination of micromechanical test and nondestructive acoustic emission (AE) to find the optimal conditions for desirable final performance. Dynamic contact angle was measured for Ramie and Kenaf fibers and correlated the wettability properties with interfacial adhesion. Mechanical properties of Ramie and Kenaf fibers were investigated using single-fiber tensile test and analyzed statistically by both unimodal and bimodal Weibull distributions. The effect of clamping on the real elongation for both Ramie and Kenaf fibers was evaluated as well. Two different microfailure modes, axial dedonding and fibril fracture, coming from fiber bundles and single fiber composites (SFC) were observed under tension and compression. They were evaluated optically and also determined by AE and their FFT analysis nondestructively.     

Evaluation of reinforcement on the mechanical behavior of partially bonded fiber/matrix interface

This paper aims at introducing a new natural composite used as soil stabilizer with particular application in geotechnical engineering. The fibers introduced in the present study could be used as effective soil reinforcement. This research proves the feasibility of the use of modified jute/polypropylene in lime and cement composites and studies their effects on the tensile and compressive strength of the matrix. In general, the optimal mechanical performance of natural composites and durability depends on the optimization of the interfacial bond between natural fiber and matrix. Since the fibers and matrices are chemically different, strong adhesion at their interfaces is needed for an effective transfer of stress and bond distribution throughout an interface. In this paper a theoretical approach for the identification of elastic modulus in composite interfaces is proposed in detail with a reasonable error. The theoretical approach is based on the method using a sum of least squares criterion. The approach is applied through optimization techniques, using analytical sensitivities and correlating adhesion with Young's modulus. The validity and potentiality of the proposed technique is discussed and the results demonstrated the versatility, accuracy, and efficiency of the presented approach. The applied method also appears to be a simple way of predicting the modulus of elasticity in composite interfaces. This leads to a discussion of the most promising stabilization methods for soil reinforcement and the outlook for the future.     

Resin–Sisal and Wood Flour Composites Made from Unsaturated Polyester Thermosets

Short fibers and wood flour were selected as fillers in the production of two types of unsaturated polyester composites (bisphenolic and isophthalic-based thermosets). Sisal fibers were subjected to washing in order to remove the organic coating on the fibers (which were originally prepared for cord manufacture) and to maleic anhydride (MAN) esterification. The effect of these treatments on the thermomechanical properties of the composites, as well as on the mechanical properties (flexural and compression) and water absorption was investigated. All the results are coincident in showing the improved interfacial adhesion obtained by washing and mainly by esterification of the fibers. Additionally, hybrid wood flour sisal composites were prepared and their mechanical properties compared to those of the one-filler composites. The hybrid composites showed improved modulus and maximum stress.     

Novel Jute/Polycardanol Biocomposites: Effect of Fiber Surface Treatment on Their Properties

In the present study, novel biocomposites with chopped jute fibers and thermosetting polycardanol were prepared using compression molding technique for the first time. Prior to biocomposite fabrication, jute fiber bundles were surface-treated at various concentrations using 3-glycidoxypropyltrimethoxy silane (GPS) and 3-aminopropyltriethoxy silane (APS), respectively. The interfacial shear strength, flexural properties and thermal properties of jute/polycardanol biocomposites reinforced with untreated and silane-treated jute fibers were investigated by means of single fiber microbonding test, three-point flexural test, dynamic mechanical analysis, thermogravimetric analysis and thermomechanical analysis. Both GPS and APS treatments played a role in improving the interfacial adhesion, reflecting that the organofunctional groups located at the end of silane coupling agents may contribute to linking between jute fibers and a polycardanol resin. As a result, it gave rise to increased interfacial shear strength of the biocomposites. Such interfacial improvement also led to increasing the flexural strength and modulus, storage modulus, thermal stability and thermomechanical stability.     

导电聚合物的现场电导/电化学研究——聚(3-甲基噻吩)和聚噻吩

本文提出一种研究导电聚合物的现场电位、电导测量/电化学方法。该实验方法基于一种可重复使用的玻璃碳-碳纤维组双电极。用该方法研究了聚(3-甲基噻吩)和聚噻吩的现场电位、电导/电化学行为。