Natural fiber-based composites are applied in many structural engineered products from civil constructions to automobile manufacturing due to the properties such as low density, high aspect ratio, biodegradability and ease to work. During the past decades such composites have been thoroughly studied for their mechanical properties and failure behavior and their properties compared with those of synthetic fiber-based composites. Other properties, such as the thermal behavior of Natural fibers and composites, have also been studied because they determine the performance of their products possible. It deals with the effect of temperature on adhesive curing, effect of high temperature and fire damage during fabrication. Further, the thermal properties have equal importance in structural applications such as temperature transfer from end to end, load capacity at specific temperature, material behavior and dimensional stability at high temperature. In this respect the isothermal and non-isothermal thermogravimatric analyses are discussed and the improtance of glass transition temperature is studied during prepapration of composites to ensure their ultimate properties. Although there are several works that have been done on thermal behavior, especially thermogravimetric analysis of Natural fibers and their composites, there is no review article available specially focused on Natural fiber-based composites, hybrid composites, and nanocomposites. The aim of this review was to focus on the advances in the comprehension of thermogravimetric behavior of Natural fibers and compare the effect of Natural fibers as reinforced materials in polymer composites.

Nowadays, the use of photocatalysts in the removal of water pollutants is very much considered. Meanwhile, titanium dioxide with unique properties has a special place. The functional drawbacks of photocatalytic nanoparticles have led to the production and application of their various geometric structures. Synthesis of fibers is performed as a single-dimensional structure in a variety of methods. In this study, TiO2 fibers were synthesized using Natural silk. Silk fibers, with good surface properties, uniformity of size and easy removal, are the perfect choice for producing nano-fibers. The synthesized structure was evaluated by analyzing XRD, SEM, FTIR, and BET. The results showed that after calcination at 450° C, there are only two anatase and rutile phases in the fibers. In fact, the sample was removed entirely from silk by heating and other analyzes also confirmed this. The photocatalytic performance of the synthesized fiber was analyzed by removing methyl orange. After 210 minutes, 94% of the dye was degraded by TiO2 fibers.

The main objective of this experimental study is to valorize local materials in order to use them as composite Materials (CM) for construction. In this study case, the CM is composed of fibers of Luffa sponge embedded in plaster. Although material resources are abundant in Tunisian territories, their use is very limited. Plaster, the by-product of heat treatment of gypsum, is used in building as coatings and decorative elements. Despite its satisfactory isolation, it has a weakness in its mechanical strength. In this research study, we focus on the enhancement of the thermo-mechanical properties of plaster by adding Luffa sponge fibers into its Matrix. The experimental studies rely on varying the mass fractions of Luffa sponge fibers chemically treated by an alkaline solution (NaOH) in the plaster matrix and then testing thermo-mechanical and physical properties. The results showed that an adequate optimum compromise linking all properties (mechanical, thermal, and chemical) is reached by CM made up of 1% Luffa sponge fibers for the following condition of chemical treatment of 1% NaOH at a temperature of 50°C for 90 min.

Silkworm cocoon is a Natural biological and composite structure that has evolved over time and has high physical and mechanical properties against stress and acts as insulation against ambient temperature conditions. Understanding the relationships between the two-component structure of silkworm cocoons (sericin and fibroin) inspires the creation of composite structures, including lightweight, high-strength nonwoven biocomposites. In the present study, by analytical-descriptive method, we have tried to use cocoon sericin and introduce some famous and widely used Natural fibers in materials science and study their characteristics - because for various reasons such as lightness, lack of pollution and low cost, etc. can be suitable alternative for a replacement of synthetic fibers - suggest the production of non-woven bio-composite materials. Natural fibers such as jute, hemp, flax, etc. with different volume percentages in combination with sericin as a binder, were proposed for this biocomposite and the thermal performance of each of them was compared using Maxwell's theoretical model. All compounds show low thermal conductivity and jute-sericin biocomposite with 70% by volume and 0.061 W/m2-K performance has better performance.

In this study, dyeing of two regenerated polyester fibers, poly-trimethylene terephthalate (PTT) and poly-lactic acid (PLA), with Natural dyes were compared with that of poly-ethylene terephthalate (PET) fiber. Lac was used as the primary Natural colorant while Catechu was chosen as a Natural color that can also act as a biomordant. The effects of temperature, initial pH of dye bath and dyeing time on color strength of the fibers were examined with Lac and Lac-Catechu combination. The results indicated the regenerated polyester fibers to have more number of functional groups and less compact structure than PET, favoring dyeing under milder conditions. PTT exhibited higher color uptake than the other fibers. Also, with Lac and Catechu in the same dye bath, the color strength was found to increase for all fibers, indicating that Catechu acted as a biomordant. Response Surface Methodology (RSM) based on 23-Central Composite Design (CCD) was used for optimization of dyeing of PTT with Lac-Catechu combination. The optimal values for temperature, initial pH and dyeing time were found to be 127OC, 6 and 26 min, respectively. The quadratic regression model developed was found to be statistically significant using ANOVA, with R2-value and adjusted R2-value of 0. 9708 and 0. 9271 respectively.

By increasing the level of public awareness, more recyclable and Natural materials are used. The aim of this research was to fabricate Natural fiber reinforced composites and to investigate the effects of fiber length (5mm and 9mm), fiber mass percent (5%, 10%, 12. 5%, and 15%), and fiber surface treatment on tensile, flexural, and water absorption properties of the fabricated composite. The experiments were designed, by the Taguchi method. In this research, epoxy resin and kenaf fiber have been used. Tensile, flexural and water absorption tests were performed on the samples. The highest values were 37. 67 MPa for tensile strength, 4. 94 GPa for tensile modulus, 31. 78 MPa for flexural strength, and 6. 05 GPa for flexural modulus. The lowest percentage of water absorption was 0. 3%. Alkali treatment improved tensile, flexural, and water absorption properties. The optimum of fiber mass percent was 12. 5% to maximize tensile strength, tensile modulus, and flexural strength, 10%to maximize flexural modulus, and 5% to minimize water absorption. Except for the tensile modulus, the effect of fiber length on the mechanical properties of the composite is observed to be less pronounced than the other two factors. To maximize the tensile modulus, the fiber length is better to be 9 mm. In this study, the values obtained for the tensile strength and tensile modulus of the fabricated composite are more than the ones in the previous works. Finally, the strength and tensile modulus obtained experimentally were compared with the ones obtained via two micro-mechanical models, modified rule of mixture, and modified Halpin-Tsia model.

One of the mechanical methods of soil stabilization is the use of reinforcing elements such as geotextiles, geogrids and Natural or artificial fibers. In recent years, the use of disconnected artificial or Natural fibers has become commonplace with random distribution to improve the mechanical properties of soil. A new type of fiber that has a Natural origin and its production and application has the least environmental impact is basalt fiber. The prominent advantages of this type of fiber are the high resistance in acidic, alkaline and saline environments, and mechanical properties that are competitive with other fibers. In this study, in addition to identification tests, a series of modified compression test, uniaxial compressive strength test and indirect tensile strength test and SEM electron microscopy was tested on clay stabilized with basalt fiber with random distribution. The focus of this research was mainly on the effect of fiber length and weight percentage on soil resistance parameters. For this purpose, basalt fibers were mixed with soil in weight percentages of 0. 25, 0. 5, 0. 75, 1, 1. 5, 2 and with three different lengths of 6, 12, 25 mm, then compressed with optimum moisture content. The results show that by increasing the weight percent and length of the fibers, compressive strength and tensile strength, initially increases and then decreases. But in general, the compressive strength and tensile strength of the reinforced soil is more than unreinforced and in all cases, reinforced samples are more ductile than unreinforced specimens.

The objective of this study was to investigate the production of Natural-cement composite fiber using poplar, wheat straw and three types of additives. In this study, variables in making the boards were: usage percent of wheat straw (0, 15 and 30%) and fibers of poplar (70, 85 and 100%), and levels and types of additives (three levels and three types of additives, i. e. calcium chloride, magnesium chloride and calcium hydroxide, respectively). After producing test specimens, compressive strength (1, 3, 7 and 28 days), thickness swelling (TS), the modulus of rupture (MOR), and internal bond (IB), were evaluated. The highest and the lowest compressive strength (32. 5 and 7. 1 MPa) after 28 days were respectively for samples containing 7% calcium hydroxide and 3% magnesium chloride. Also, the boards with 30 percent wheat straw and 70 percent poplar wood fiber with the amount of 3% calcium chloride had a higher MOR compared to other boards. In general, the results suggest that calcium chloride additives with amount of 5% and the average value of 15% straw to 85% poplar is the appropriate amount for achieving acceptable values of IB and MOR. Due to its significance in the statistical analysis, the model presented by Response Surface Methodology provided a suitable and significant estimate to determine the application of the variables.

One of the enormous challenges of bio-composites is the improvement of the flexural and impact strength. Therefore, the optimization and parametric investigation of nanocomposites reinforced with Natural hybrid fibers is the main focus of this study. Kenaf/basalt/nanographene fibers in polypropylene were used to reinforce bio-composite specimens. Response Surface Method (RSM) was applied to study and present a mathematical model for the performance of bio-composite according to a number of parameters including the basalt fiber weight percentage, kenaf fiber as well as nanographene. The performance of the specimens was discussed under the bending and impact tests and the outcomes were explained by the use of FESEM images. The optimal value of the parameters was set as a multi-objective according to the increase of the flexural strength and energy absorption, the reduction of the specimens’ weight, and also a Pareto diagram was illustrated considering the design goals. The findings revealed that the composite specimen with the best flexural behavior had the flexural strength of 51.2558 MPa, which consisted of 0.8723 wt% of basalt fibers, 15% of kenaf fibers, and 0.76881% of graphene nanoparticles. In addition, the best specimen in terms of impact had 116,809 J / m energy absorption, which included 8.23% basalt fibers, 0.808% graphene nanoparticles, and 15% kenaf fibers.