Contact angle of modified fibrovascular bundle of salacca (Salacca sumatrana Becc.) frond by NaOH+Na2SO3 combination

The fibrovascular bundle (FVB) of the salacca frond is one of the potential raw materials in the development of bio-composite technology. The purpose of this study was to investigate the wettability of FVB using the contact angle method after the alkali modification treatment. The method of this research was to use FVB frond of Salacca sumatrana Becc. which was treated with alkaline modification of the combination of NaOH+Na2SO3 at various concentrations. The results showed that the combination of NaOH 1M+Na2SO3 0.4 M had the smallest contact angle, which means that the FVB has a good wettability value compared to the control treatment. Based on the results, it can be concluded that the modification of NaOH+Na2SO3 can increase the wettability of FVB.

Effect of Modification Methods of Wheat Straw Fibers on Water Absorbency and Mechanical Properties of Wheat Straw Fiber Cement-Based Composites

Five modification methods are adopted for wheat straw fibers (WSFs). The effects of modification methods on the water absorbency of wheat straw fiber/wheat straw fiber cement-based composite (WSFCC) and the mechanical properties of WSFCC are analyzed. The crystallinity, chemical structure, and micromorphology of WSFs and WSFCC 28-day specimens are characterized by XRD, FTIR, and SEM methods. The results show that the water absorption of WSFs modified with sodium silicate solution, pure acrylic acid emulsion, and silicone waterproof emulsion surface spraying is 10.67%, 5.18%, and 1.05% lower than that of unmodified WSFs, respectively. Alkali modification is the ideal method for improving the strength of WSFCC. Establishing a fitting formula of the relationship between water absorption of WSFs and strength of WSFCC specimens has important theoretical and practical guiding significance for development and application of WSFCC.

Effect of Straw Fiber Modification Methods on Compatibility between Straw Fibers and Cement-Based Materials

To improve the utilization of crop straws as a resource and the compatibility between straw fibers and cement-based materials, the hydration of modified straw fiber cement-based composite (SFCC) was studied. The structural characteristic of SFCC was investigated by FTIR, SEM, and XRD. The results show that the setting time of several modified straw fiber SFCC pastes was shorter than that of the unmodified straw fiber SFCC paste, and the best method of fiber modification to improve the setting time of the SFCC paste is Na2O·nSiO2 treatment. The recommended fiber modification method for improving the compatibility between straw fibers and cement-based materials is alkali modification, followed by pure acrylic emulsion modification and Na2O·nSiO2 modification. To improve the strength of SFCC, the straw fiber should be modified by alkali, followed by pure acrylic emulsion and Na2O·nSiO2 modification and the method of water modification is also recommended. The phase types and relative contents of crystalline hydration products mixed with the modified straw fiber SFCC are significantly higher than those of the unmodified fiber SFCC. The fiber treatment method that was most helpful to increase the structural density of hydrates of SFCC was alkali treatment and pure acrylic emulsion treatment, followed by Na2O·nSiO2 treatment.

Preparation and Performance of Different Modified Ramie Fabrics Reinforced Anionic Polyamide-6 Composites

Anionic polyamide-6 (APA-6) composites are prepared by the VARIM process using different modified ramie fabrics to study the structure and properties of different composites. This study can not only evaluate the optimal modification method for the ramie fabrics, but also further explore the interface interaction mechanism between ramie fabrics and APA-6. In this article, the ramie fabrics are modified by a pretreatment, coupling agent and alkali modification. Different modification methods have different effects on the structure, surface properties and mechanical properties of ramie fabrics, which will further affect the impregnation process, interfacial and mechanical properties of the composites. Through the performance analysis of different modified ramie fabrics reinforced APA-6 composites, the conversion, crystallinity and molecular weight of these composites are at a high level, which indicate that the polymerization of these composites is well controlled. The coupling agent modified ramie fabrics composites and the pretreated ramie fabrics composites have higher flexural modulus, tensile strength and dynamic mechanical properties. Alkali-modified ramie fabrics composites have slightly lower mechanical properties, which however have the highest interlaminar shear strength and outperformed interface properties of the composites.