Polystyrene Waste Recycling Process as an Alternative Antistatic Packaging Raw Material

. Composite synthesis from styrofoam (polystyrene-based) was carried out by solvent blending method in which the solvent used was gasoline. The carbon black (CB) was used as filler comes from coconut shells. The samples were given a variation of filler composition: 0, 1, 3, and 5% of the total weight of the composite to be formed. In this method, stirring was carried out for at least 120 minutes (200 rpm in atmospheric conditions). The stirring process is carried out until the mixture becomes homogeneous, as indicated by the slurry formation. After that, the process continues to the printing stage using glass mold and drying in a windy room that is sufficiently exposed to sunlight for 3 days. The sample obtained is a composite measuring 8 cm x 8 cm. The tests carried out were the ATR-FTIR, SEM, conductivity, and mechanical tests. From the results of the ATR-FTIR test, there was no visible difference between the styrofoam before being treated with the composites, thus proving that the solvent had evaporated. The results of the SEM test show that there are lumps in the sample with higher filler concentrations, so it is possible to need additional time or stirring speed to distributed the filler evenly. Meanwhile, the conductivity test proved that the addition of carbon-based filler could increase the conductivity of the composites.


Introduction
Plastics have become a part of life.Even the use of plastic in Asia reaches 20 kg per person per year and is predicted to continue to increase [1].However, the increase in the use of plastic is not matched by an increase in waste management.The disposal of plastic waste, both in the ocean and on land (landfill), causes a global problem and is the concern for many parties.In Indonesia, the ban on the use of plastic already exists in several areas.However, this regulation is not evenly distributed and has not been supported by binding regulations, so many people still ignoring plastic waste.
Polystyrene (PS) based plastic is a dominant plastic derivative product.PS is a type of plastic that is easy to form at high temperatures and is very stiff at room temperature.PS we find a lot of food packaging and electronic devices that we usually know as Styrofoam.Its use is still a favorite because it is very profitable in terms of economy, not easy to leak, practical, and lightweight [2,3].
PS waste management must be handled seriously because it can cause environmental pollution.Due to its non-degradable nature, when discharged into the environment, PS waste will decompose into macro, micro, or nanoparticles through various processes [4].Several attempts to reduce PS waste are by making it as fuel through the pyrolysis process [5,6].In addition, PS also has the potential to be recycled mechanically, chemically, and thermally [7].The results of PS waste recycling can be used as a basic material for antistatic packaging.
Antistatic packaging is mostly used in the electronics industry to avoid damage to electronic components caused by electrostatic discharge (ESD).This packaging protects electronic devices that are sensitive to electrostatic charges resulting from friction during storage or distribution.Antistatic packaging is made of a polymer matrix with the addition of antistatic agents or fillers which can be carbon-based materials such as carbon black, graphite, carbon nanotubes, graphene, and carbon glass [8,9].
In this first research stage, PS was mixed from Styrofoam-based food packaging waste with carbonbased filler in the form of carbon black (CB).The focus of the research is to investigate the characteristics of the formed conductive polymer composites to facilitate further research to develop the results of this research, especially for its use and fabrication.

Materials and Methods
The research methodology can be seen in Figure 1.Polystyrene (PS) is obtained from commercial Styrofoam-based food packaging which is cut into small pieces.Gasoline with the composition 92% iso-octane and 8% n-heptane, supplied by PT Pertamina, was used as the solvent.The SuperP conductive Carbon Black (CB) from CHEMTEL MTI Co., USA was used as the filler in micro-size (less than 20 µm in diameter).All materials were directly mixed in 25 mL solvent using a beaker glass at room temperature by stirring at 200 rpm for two hours.The composition of the material and nomenclature of the samples are shown in Table 1.Then, the homogeneous solvent was poured into an 8 cm x 8 cm glass mold and dried at atmospheric conditions for 3 days.Several characterizations were carried out to determine the properties of the samples formed.The Attenuated Total Reflectance Fourier transform infrared (ATR-FTIR) test was done using the Shimadzu IR Spirit tool to analyze the functional groups at wavelength 400-4000/cm.The morphological structure of the sample was analyzed using the JEOL Benchtop Scanning Electron Microscopy (SEM) JCM 7000 with magnifications of 5,000x.The sample impedance was measured using ZC -90G Insulation Resistance Tester Shanghai Taiou Electronic to determine the conductivity.

Result and Discussion
Gasoline was used as an organic solvent in the solutionblending process to make polystyrene-based composites.The polystyrene used comes from food packaging waste, Styrofoam.Carbon black (CB) was added as filler to improve its conductivity.Styrofoam that had been dissolved in the solvent was given various CB concentrations and the mixture was stirred at 200 rpm for two hours.Then, the mixture was poured into a glass mold and dried in atmospheric conditions.The glass mold was placed in a windy room and exposed to sufficient sunlight to speed up the drying process.So that the composite did not tear and change shape easily, the drying process was carried out for 3 days to ensure the composite was completely dry and stiff.The composite formed in the form of a sheet measuring 8 x 8 cm2 with a thickness of around 0.5 mm was then characterized.
The first characterization carried out was Attenuated total reflectance Fourier transform Infrared (ATR-FTIR) using Shimadzu IR Spirit.This test was conducted to see if solvent was successfully drained from the samples.Styrofoam that has not been treated was used as a control.The results can be seen in Figure 2. From the test, there was no significant difference between untreated Styrofoam and the composite samples, Styrofoam which had been solvent blended.This indicates that the solvent has completely evaporated.Then, the test using JEOL Benchtop Scanning Electron Microscopy (SEM) JCM 7000 was performed to determine the surface morphology of the samples.The composite morphology was observed to determine the filler distribution in the composite.This observation of the samples was viewed from one side, namely on the surface of the sample observed at 5000x magnification.Based on the results of the SEM test (Figure 3), it can be seen that the morphology and particle size obtained varied.
In Figure 3(a), it can be seen that lumps occur in several parts of the morphology of the composite.The clumping is caused by the lack of a long mixing process between polystyrene with solvent and CB.However, in Figure 3(b) it can be seen that fewer lumps are formed even though there are visible air cavities on the composite surface.The air voids are caused by trapped air during the pouring process, causing poor bonding between the filler and the matrix [10].The air is pushed out during the drying process of the composite in an open space and causes cavities to form in the composite.Meanwhile, in Figure 3(c), it can be seen that the lumps are denser and more numerous than in Figure 3(a).This is due to the addition of the percentage of CB in the composite so that it requires a longer stirring time than the previous sample.Figure 3(d) shows that the sample contains the most undissolved polystyrene compared to the other samples.Based on the results obtained, additional time or speed of stirring may be needed so that the filler is distributed evenly.The electrical conductivity was measured using the ZC-90G Insulation Resistance Tester from Shanghai Taiou Electronic.This test was carried out based on the composition of CB in different sample compositions.The sample size was 8 cm x 8 cm with a thickness of approximately 0.5 mm.The results are shown in Figure 3.The conductivity value is indicated by the impedance or electrical resistivity value and then calculated with the following formula: where D1 is the diameter of the measuring electrode (50 mm), g is the gap between the measuring electrode and the guard electrode (2 mm), and h is the thickness of the tested sample.
Figure 4 shows the sample's specific electrical resistivity, confirming that the decrease in resistivity is influenced by the amount of filler added.The addition of filler succeeded in reducing the resistivity of the composite from 5.590 x 10 19 for pure Styrofoam to 1.070 x 10 8 for the sample with CB addition.This decrease is inversely proportional to the amount of filler added.Composite resistivity is respectively 3.299 x 10 11 , 2.942 x 10 8 , and 1.070 x 10 8 for composites with %, 3%, and 5% CB filler.The increase in conductivity occurred significantly from pure Styrofoam to the 1%CB and 1%CB to 3%CB.But from 3%CB to 5%CB the sample conductivity did not increase significantly.

Conclusion
The CB/Styrofoam composite preparation has been successfully carried out by mixing the solution with gasoline as a solvent.Sample drying was done by placing the sample in an open space.However, ATR-FTIR spectra demonstrated that the material did not contain any solvent residue.Because of Styrofoam is an electrical insulator, filler needs to be added to increase its conductivity.One of the carbon-based fillers used in this research, CB has been proven to increase conductivity when used as a filler.The filler's addition allowed it to be used as a semiconductor material as well.The addition of CB is proportional to the conductivity, as evidenced by the reduced impedance.The sample with 95% Styrofoam and 5% CB has the lowest impedance value of 1.070 x 10 8 Ωm.