The method used for sampling was called non-probabilistic sampling, sometimes referred to as the empirical or rational choice method. It involves a non-random selection process based on subjective criteria that vary depending on the interviewers’ choice, feasibility criteria, and similarity to the target. The large amounts of plastics found in landfills serves as justification for the technique’s selection. Three sampling points are part of the sampling plan. The following equipment is required for this operation:

The raw materials used in this work was organics totally such as PS waste that are a plastic polymer, organic solvent and Spider silk, which is a polymer-based fibre.

When the material to be processed requires polystyrene that is not contaminated by food remnants (soup, food residues) and is free of coloring and labels, this landfill garbage must be prepared as follows:

Figure 2 shows a flowsheet preparation of the raw material (polystyrene).

The d-limonene-based solvent was made up of 2/4 limonene, 1/4 copper II sulphate, and 1/4 alkaline compound. This combination was created with the goal of increasing the solubilising power of the reagent used to dissolve all polystyrene and other types of plastic. Limonene is a semi-polar organic solvent with the qualities listed in Table 1 below.

The choice of d-limonene was driven by the fact that it is more than 30% natural, non-toxic (when used as directed and with proper safeguards), and biodegradable, as opposed to toluene, acetone, or sulfuric acid. Furthermore, it is not combustible at room temperature and emits no harmful fumes; it is also more stable and soluble than other solvents. Table 2 shows the characteristics of the copper II sulphate used to prepare the solvent.

Following processing, the resulting solvent has a dark blue hue, as seen in Figure 3 bellow.

The basis of solvolysis (dissolution) is that the solute forms low-energy bonds with the solvent, has double bonds in its structure, and protons in positions 2, 3, 8, and 9, as shown in Figure 4 below.

The resulting d-limonene-based solvent was poured into a reaction vessel, as seen in Figure 5 .

In contact with the polystyrene at room temperature with a modest agitation of 1 rpm, the dissolving rate of the polystyrene is satisfactory in a quick and spontaneous reaction as illustrated in Figure 6 , 20 seconds after the polystyrene encounters the solution. It is worth noting that the solvent dissolves different types of thermoplastic polymers, as shown in Figure 6 .

Following the dissolution of polystyrene and other thermoplastic polymers, filtering was used to separate the solute (recycled PS) from the solvent. Polystyrene was then dissolved and reduced to one-twentieth of its original volume. The recycled polystyrene was found in the form of thick granules.

Because d-limonene acts as an antioxidant, the recovered solvent retains its properties throughout the process and can be reused. It stops electrons from leaving the atoms as the PS dissolves. As a result, the molecular weights remain constant, and the material retains its properties. Most EPS recycling processes known to date are carried out at high temperatures, which causes degradation of the molecules, resulting in a recycled material with weaker mechanical properties due to oxidation.

It should be observed that the content of the solvent had virtually no impact on the composition of the solute, i.e. polystyrene. The operating settings are provider in Table 3 .

Figure 7 illustrates the polystyrene dissolution process.

At this point, it is crucial to note that the recycled polymer contains the same proportion of solutes by weight after the solvent has been completely evaporated as it did before treatment. This enables us to classify the approach as lossless. It should be mentioned that the re-polymerization mechanism has not been fully understood due to challenges in witnessing the reactions in progress. As a result, the material obtained is suitable for usage as a matrix in our composite material. The procedure will be followed in accordance with a predetermined standard, taking into consideration the availability of laboratory equipment and the resources at our disposal.

It should also be emphasized that the recycled PS was moulded into sheets, and the reinforcement, spider silk woven using the SIC-SIC process, was layered on top to create a sandwich structure.

The penetration test is a laboratory procedure designed for manipulation. The goal is to determine the bullet-proof waistcoat’s capacity to withstand penetration by a sharp object, or in this case, a high-velocity projectile, as it moves helical. In this method, we can assess the level of protection it can provide against stabbing weapons and bullets, ensuring the wearer’s safety.

Testing fibre elongation upon impact or breakage: Micro-fractures are the primary means by which composite materials absorb impact energy. This means that energy absorption is heavily influenced by the breaking tension of the fibres. When the fibres break, no additional energy is absorbed. One could expect the energy to be absorbed by plastic deformation or fibre geometry. A piercing machine was used to assess fibre elongation on impact, and the results are shown in Table 4 .

The obtained results were compared to existing values to draw conclusions based on the objectives pursued by our work, namely the feasibility study and evaluation of the performance provided by a composite material for ballistic use who’s ceramic and/or metal inserts will be replaced by a recycled polystyrene insert and whose reinforcing material is hand-woven spider silk fibre. Table 5 illustrates the physical properties of polystyrene-based materials.

The modulus of elasticity values is provided in Table 6 .

When we compare polystyrene supplied on the market to other materials such as carbon or glass fibre composites or steel, we see an obvious difference: its Young’s modulus is lower than that of its neighbours. Despite these major variances, polystyrene remains the most popular bumper material.

Laboratory study on materials based on recycled polystyrene produces the following results in Figure 8 below.

The colour of the polymer changed when it was mixed with the dye, and this occurred when our materials set. The setting mechanism involves trapping a lower amount of solvent, air, and other ambient vapours, as evidenced by the visual presence of air bubbles in the test tubes.

Table 7 below shows the characteristics of molded polystyrene plates.

Composite materials rarely contain the reinforcement utilized. Materials experts refer to it as the material of the future. Simply put, it’s silk (spider) fibre. Table 8 below describes the format used in our composite material.

Figure 9 illustrates the layers of hand—woven silk.

Bullet-proof waistcoats do not immediately stop bullets; instead, they absorb their kinetic energy and distribute it throughout the waistcoat’s full surface. To accomplish this, the material must have closely intertwined fibres. Individual fibres are typically twisted to increase density and thickness at each location. To increase rigidity, the material is covered with resin and clamped between two layers of plastic film. A person wearing a bullet-proof waistcoat will always feel the energy of a bullet’s impact across their entire body rather than just one place. If everything works perfectly, the sufferer will not sustain major injuries.

The waistcoat’s components are meticulously picked. For example, the material that will be struck initially must have unique properties that allow it to function as a bumper.

The different Rockwell hardness values for the materials compared with polystyrene are presented in Table 9 below.

As a result, we will display the results of our testing using a graph (diagram), as illustrated in Figure 10 .

We observe a significant difference in the hardness of polystyrene supplied on the market as bumper material for home appliances and that of the polystyrene we have recycled, with values lower than those of carbon/silica-based ceramics or, even more so, steel. This allows us to confirm our material’s progressive mechanical qualities following recycling. Composite materials have been used in a variety of military applications, replacing metals, ceramics, and other ballistic materials. A material’s ability to give protection (stopping a projectile in its tracks) on contact is determined by its hardness, which is critical when ‘blunting’ a projectile.

The mechanical tests produced for our application are the simple compressive strength and tensile tests, which were performed just on polystyrene specimens and not on the composite.

Table 10 below shows the results of the tensile tests carried out on the material.

We will therefore represent the results of our tests in graphical form as shown in Figure 11 below.

Figure 11 indicates that polystyrene recycled by solvolysis has 20 times greater tensile characteristics than expanded polystyrene. The rise in tensile and other properties can be attributed to the materials’ structure prior to, during, and after dissolution and setting. Considering the contribution of the improved qualities of the recycled polystyrene to the composite material created a few tests on the composite materials were enough to make a preliminary conclusion on the efficiency of the technique used.

Table 11 displays the fibre elongation at break values (in MPa) for some of the materials utilized in body armour design.

The penetration of a drill with the above-mentioned parameters is measured in millimetres per second. This demonstrates the efficiency of the composite material produced in maintaining the projectile while it moves at high speeds, rotates, and pierces (helical movement). Body armour is intended to protect the torso from shards of exploding shells, grenades, shattered mines, and bullets fired from small guns. This armour protects against bullets of calibre.22 to.30, with a notional mass of 2.6 to 10 g and a velocity of 436 to 869 m/s when shot at 5 m (NIJ Standard 01.01.04).

Considering this, it becomes reasonable to conclude that the composite material has a high resistance and retention capacity, which is enhanced by the inversion of the woven silk threads. The maximum penetration of the bullet is 45˚ for 1 cm, therefore the composite has a value of 0.9 cm for 45˚ after 5 seconds.

Tests on genuine projectiles (ballistic kind) revealed that the waistcoat had a high retention capacity for handgun rounds, as indicated in Figure 12 below.