Recycled jute fabric cloths as skin layers and jute mat as a thick core were used as natural fiber reinforcements for unsaturated polyester matrix composites via modifying the hand lay-up technique with resin pre-impregnation into the jute in vacuum. The effect of skin jute fabric and the fiber weight content on the impact properties and fracture behavior of above-mentioned composites were investigated. The results showed that Izod impact strength increases by increasing the fiber weight content. The total impact energy was increased to about five times for different fiber weight content compared to the value of neat resin and the jute cloth has a slightly effect on the total impact energy compared to the jute mat composites.

The main objective of this research is to study the effect of notch on the tensile strength and characteristic distance of Jute fiber mat reinforced unsaturated polyester matrix composites. These composites were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in the vacuum with 32 wt% fiber weight content. For this purpose, circular notch with diameter 10.2 mm was drilled at the specimen center with different widths. Therefore, the effect of the different ratios of the notch size to the specimen width (D/w) with three different values (0.34, 0.44, 0.59) on the characteristic distance (d0) and on the ratio of notched to unnotched strength (σN/σo) based on the net and the gross area was investigated. The characteristic distance d0 is a material property independent of laminate geometry and stress distribution and represents the distance over which the material must be critically stressed in order to find a sufficient flaw size to initiate failure. The results show that as D/w increases, d0 decreases and it is much lower for which based on the net-section than those based on the gross-section. As a result of that, the tensile strength of the jute composites based on the net-section is insensitive to the notch, while it is very sensitive to the notch based on the gross-section compared to the tensile strength of unnotched composites. As expected, σN/σo based on the net-section was higher than that based on the gross area and σN/σo based on the gross area decreases significantly with increasing D/w due to the stress-concentration ahead of the notch.

The main objective of this research is to study the effect of notch on the tensile strength and characteristic distance of Jute fiber mat reinforced unsaturated polyester matrix composites. These composites were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in the vacuum with 32 wt% fiber weight content. For this purpose, circular notch with diameter 10.2 mm was drilled at the specimen center with different widths. Therefore, the effect of the different ratios of the notch size to the specimen width (D/w) with three different values (0.34, 0.44, 0.59) on the characteristic distance (d0) and on the ratio of notched to unnotched strength (σN/σo) based on the net and the gross area was investigated. The characteristic distance d0 is a material property independent of laminate geometry and stress distribution and represents the distance over which the material must be critically stressed in order to find a sufficient flaw size to initiate failure. The results show that as D/w increases, d0 decreases and it is much lower for which based on the net-section than those based on the gross-section. As a result of that, the tensile strength of the jute composites based on the net-section is insensitive to the notch, while it is very sensitive to the notch based on the gross-section compared to the tensile strength of unnotched composites. As expected, σN/σo based on the net-section was higher than that based on the gross area and σN/σo based on the gross area decreases significantly with increasing D/w due to the stress-concentration ahead of the notch.

Jute fiber mats-reinforced unsaturated polyester matrix composites having different fiber weight contents (11, 22, 32 wt%) were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in vacuum. This modification showed a better impregnation of resin throughout the jute mats and lower voids contents in the composites. Two types of impact tests, swing pendulum (Izod) and drop weight (impulse) were carried out to evaluate the effect of fiber contents on the impact properties of these composites. The Izod impact strength and impulse impact energy increase as the fiber content increases and the improvement had occurred at 11 wt% fiber content compared to that of the neat resin. Moreover, the fracture surface has demonstrated that fiber pull out mechanism is the predominant failure mode for different fiber weight contents. The total energy increases with fiber contents of 11 and 22 wt% to about three times, whereas the total energy increases at 32 wt% to about four times compared to total energy of neat resin. Multiple matrix cracking with fiber pull-out mechanism was revealed from the impulse impact test of the composites

Jute fiber mats-reinforced unsaturated polyester matrix composites having different fiber weight contents (11, 22, 32 wt%) were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in vacuum. This modification showed a better impregnation of resin throughout the jute mats and lower voids contents in the composites. Two types of impact tests, swing pendulum (Izod) and drop weight (impulse) were carried out to evaluate the effect of fiber contents on the impact properties of these composites. The Izod impact strength and impulse impact energy increase as the fiber content increases and the improvement had occurred at 11 wt% fiber content compared to that of the neat resin. Moreover, the fracture surface has demonstrated that fiber pull out mechanism is the predominant failure mode for different fiber weight contents. The total energy increases with fiber contents of 11 and 22 wt% to about three times, whereas the total energy increases at 32 wt% to about four times compared to total energy of neat resin. Multiple matrix cracking with fiber pull-out mechanism was revealed from the impulse impact test of the composites

This research investigates the processing of sandwich composite structures with overall low density made up of glass fibre-reinforced polymer skins bonded to a jute fiber mat core. Jute fibers are totally biodegradable and recyclable materials, i.e. environmentally-friendly materials. Jute fibers have good insulating properties for both of thermal and acoustic energies with moderate moisture regain and no skin irritations. The current annual worldwide production of jute fibre is about 3.2 million tones used for various applications. Bag cloth industry is the biggest consumer of jute fibers available in the markets. Jute bags have gained an advantage as being an eco-friendly option instead of both of non-biodegradable poly bags that are made from petroleum and paper bags that require large quantities of wood. A huge amount of these jute fibers is wasted and goes to landfill every year, either scraped from manufacturing of jute cloth in form of slivers or end-of-life of jute bags. Therefore, an attempt was carried out in this research to use the above-mentioned valuable properties of jute fibers, to reuse the wasted jute slivers, to recycle the end-of-life jute bags for fabricating highly valuable sandwich structured composites. The sandwich composite structures are usually fabricated by attaching two thin but stiff skins to a lightweight but thick core. The jute fibre slivers were blended with chopped jute fibers that obtained from hashing the used coffee grain bags to produce a lightweight thick jute fiber mat. This jute fiber mat was padded as core material between two stiff thin skin layers. Each skin layer is constructed from a single plain woven glass fiber fabric impregnated with unsaturated polyester resin by hand lay-up technique. Finally, a lightweight sandwich composite structure with reduction of cost and CO2 emission was successfully fabricated. Appropriate applications can be introduced for these sandwich composite structures as barrier walls against the thermal and acoustic energies for interior construction, lightweight panels for furniture construction, housings for electronic equipments, etc.

This research investigates the processing of sandwich composite structures with overall low density made up of glass fibre-reinforced polymer skins bonded to a jute fiber mat core. Jute fibers are totally biodegradable and recyclable materials, i.e. environmentally-friendly materials. Jute fibers have good insulating properties for both of thermal and acoustic energies with moderate moisture regain and no skin irritations. The current annual worldwide production of jute fibre is about 3.2 million tones used for various applications. Bag cloth industry is the biggest consumer of jute fibers available in the markets. Jute bags have gained an advantage as being an eco-friendly option instead of both of non-biodegradable poly bags that are made from petroleum and paper bags that require large quantities of wood. A huge amount of these jute fibers is wasted and goes to landfill every year, either scraped from manufacturing of jute cloth in form of slivers or end-of-life of jute bags. Therefore, an attempt was carried out in this research to use the above-mentioned valuable properties of jute fibers, to reuse the wasted jute slivers, to recycle the end-of-life jute bags for fabricating highly valuable sandwich structured composites. The sandwich composite structures are usually fabricated by attaching two thin but stiff skins to a lightweight but thick core. The jute fibre slivers were blended with chopped jute fibers that obtained from hashing the used coffee grain bags to produce a lightweight thick jute fiber mat. This jute fiber mat was padded as core material between two stiff thin skin layers. Each skin layer is constructed from a single plain woven glass fiber fabric impregnated with unsaturated polyester resin by hand lay-up technique. Finally, a lightweight sandwich composite structure with reduction of cost and CO2 emission was successfully fabricated. Appropriate applications can be introduced for these sandwich composite structures as barrier walls against the thermal and acoustic energies for interior construction, lightweight panels for furniture construction, housings for electronic equipments, etc.

Jute fiber mat reinforced unsaturated polyester matrix composites having different fiber weight contents (11, 22, 32 wt%) were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in the vacuum. Tension and three-point bending tests were carried out to evaluate the effect of fiber contents on these mechanical properties of above-mentioned composites. The results show that as the fiber weight content increases, Tensile and flexural properties (strength and modulus) increase. Fiber pull out mechanism is the predominant failure mode revealed at the fracture surfaces under tensile load as well as at tension side of composites under bending load.

Jute fiber mats-reinforced unsaturated polyester matrix composites having different fiber weight contents (11, 22, 2 wt%) were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in a vacuum. This modification showed a better impregnation of resin throughout the jute mats and lower voids contents in the composites. Two types of impact tests, swing pendulum (Izod) and drop weight (impulse), were carried out to evaluate the effect of fiber contents on the impact properties of above-mentioned composites. The impact properties of these composites were compared with those of neat unsaturated polyester resin material. The fracture behavior of the composites that yielded from the impact tests was characterized by observation of the composites microstructure using scanning electron microscopy (SEM). The Izod impact strength increases as the fiber content increases and the improvement in the impact strength of the composites compared to that of the neat resin occurs at 32 wt%. Moreover, the fracture surface has demonstrated single matrix crack with complete fiber pull-out at a fiber content of 11 wt%, while single matrix crack with partially fiber pull-out mechanism was confirmed at fiber contents of 22 wt% and 32 wt%. The fiber contents has a positively large effect on the impulse total impact energy of the composites, e.g. the total energy increases with fiber contents of 11 and 22 wt% to about three times, whereas the total energy increases at 32 wt% to about four times compared to total energy of neat resin. Multiple matrix cracking and fiber pull-out mechanisms were revealed from the impulse impact test of the composites. Finally, this study showed that both izod and impulse impact properties can be improved by adding 32 wt% of jute fiber mats as reinforcements to unsaturated polyester matrix composites.

Jute fiber mat reinforced unsaturated polyester matrix composites having different fiber weight contents (11, 22, 32 wt%) were fabricated by modifying the hand lay-up technique with resin pre-impregnation into the jute mats in the vacuum. Tension and three-point bending tests were carried out to evaluate the effect of fiber contents on these mechanical properties of above-mentioned composites. The results show that as the fiber weight content increases, Tensile and flexural properties (strength and modulus) increase. Fiber pull out mechanism is the predominant failure mode revealed at the fracture surfaces under tensile load as well as at tension side of composites under bending load.