Search

Ramie composites have been widely used in automobiles, daily necessities, aerospace, ships, cruise lines, etc., but their flame retardant properties are relatively poor, which is difficult to meet the flame retardant performance requirements of composites for rail transit. In order to improve the properties of ramie reinforced composites, flame retardant treatment is necessary. In this paper, phosphorus flame retardant phytic acid (PA) was used to modify ramie fabric, and then the composites were prepared. The flame retardancy and mechanical properties of ramie reinforced composites were investigated. It was found that the flame retardancy of ramie composites was improved after flame retardant modification with phytic acid, but the mechanical properties were decreased. In order to improve the mechanical properties of PA ramie composites, two kinds of layered PA ramie/glass fiber hybrid composites were prepared by replacing part of ramie with glass fiber. The results show that the addition of glass fiber can improve the mechanical properties and flame retardancy of composites. [ABSTRACT FROM AUTHOR]

The silanized graphene oxide (KH-GO) with different mass fractions was dispersed in epoxy resin by a solution blending method and resin transfer molding process. The nano indentation method was used to test the micromechanical properties of GO/epoxy composites with different mass fractions, and the effect of GO on the hardness of epoxy matrix composites was quantitatively determined, and the influence of adding KH-GO on the thermal mechanical and bending properties of epoxy resin was discussed by dynamic thermal mechanical and universal strength machine tests. The experimental results show that the thermal and mechanical properties of composites are improved with the increase of the amount of KH-GO. Especially, when the content of KH-GO was 0.3%, the bending strength (125.4 MPa), hardness (281.0 MPa), and glass transition temperature (99.6°C) of composites reached the highest. It was proved that the composites showed its excellent performance and the silane coupling agent was successfully grafted to the graphene oxide by covalent bond, which effectively improved the interface compatibility of the reinforcing body and the matrix and was related to good dispersibility in the epoxy resin. This method is simple and effective, providing a certain reference value for the enhancement of the mechanical properties of the next generation of nanocomposites. [ABSTRACT FROM AUTHOR]

Textile technology offers a plethora of design and production alternatives for composite reinforcements. In this study, highly aligned continuous hemp tape was produced based on hemp sliver and used to prepare unidirectional composites with optimized mechanical properties. The fiber content, preform areal density, and fiber orientation were considered to investigate the mechanical properties of the composite. The areal density of the hemp tape felt was contingent on the hemp sliver drafting multiple. Both composite tensile and flexural strength reached the maximum of 166.85 MPa and 207.68 MPa at drafting multiple i=2 and 30% fiber content, which were comparable with those reported for hemp fiber composites. The hemp tape was favorable for more complex shapes for applications. The superior mechanical properties and discrimination between the composites enhanced with two typical orthogonal reinforcement diversified the application potential in the field of automotive, furniture and architectural panels. • Hemp tape with highly aligned fibers was produced by self-designed equipment. • Low tape areal density aids fiber alignment accompanied with delamination risk. • Hemp tape-based composite properties are not proportional to fiber orientation. [ABSTRACT FROM AUTHOR]

The limitation of plant fiber length can be overcome by using staple spinning to achieve continuity on short fibers. Ramie fiber staple yarn reinforced unsaturated polyester composites (RSYCs) were fabricated with ramie fiber and unsaturated polyester matrix. The unique fiber packing density of staple yarn must be tackled first to reflect the structure of RSYCs. The relationship between fiber packing density of staple yarn and fiber volume fraction of composite was evaluated to investigate the effect of fiber packing density on properties and predict the tensile strength of RSYCs using the rule of mixture. A scanning electron microscope illustrated fiber packing density of staple yarn. When the twist factor was 380 with the optimal yarn count of 80 tex, the fiber packing density was 19.9% higher than that at 260. Compared with the minimum tensile strength of RSYCs at 120 tex, the maximum of RSYCs at 380 was 399.2 MPa, improved by 238.6%. Measured by dynamic mechanical analysis, the viscoelastic rigidity and damping property of RSYCs was the best at 380, with the storage modulus of 31.9 GPa at 40 °C and the tan delta of 0.1226 at 80.59 °C. Compared with the neat resin and ramie fiber, the onset temperature of weight loss of RSYCs tested by thermogravimetric was reduced. The increasing fiber packing density significantly reduced the resin permeability of RSYCs, according to the contact angle and ultrasonic nondestructive testing results. There is no doubt that the obtained fiber packing density possessed great potential for promoting the development of RSYCs. [Display omitted] • Fiber packing density adjusted by yarn count and twist factor. • Fiber packing density influenced the tensile properties of ramie fiber staple yarn reinforced composites. • Fiber packing density overruled fiber volume fraction to improve the rule of mixture. [ABSTRACT FROM AUTHOR]