What Phenomena Happen during Pyrolysis of Plastic? FTIR AND GC-MS Analysis of Pyrolyzed Low Linear Density Polyethylene (LLDPE) Polymer Particles Completed with Bibliometric Research Trend and Pyrolysis Chemical Reaction Mechanism

Abstract

This research aims to determine the compounds produced from the pyrolyzed Low Linear Density Polyethylene (LLDPE) using Fourier Transform Infrared (FTIR) and Gas Chromatography-Mass Spectroscopy (GC MS). We used pyrolysis of 985 g of 2-mm diameter LLDPE plastic ore at a temperature between 192-194°C for 135 min using a batch reactor (length x width x height = 35 cm x 24 cm x 44 cm) equipped with an outlet connected to two condensers (24°C). To ensure the chemical results, the reactor was connected in series to condensers 1 and 2. The results obtained in condenser 1 were 3 mL of 2-phase liquid with a strong odor. The upper fluid is yellow, and the lower fluid is brown. In condenser 2 (connected directly to condenser 1), 4 mL of yellow single-phase liquid was produced with a strong odor. The liquid obtained from the pyrolysis process was then analyzed by FTIR and GC-MS. FTIR results on both samples showed that the samples contained the functional groups O-H, CH₂, and C=O. The GC-MS results on condenser sample 2 showed that the pyrolysis product contained acetone compounds. This confirmed that pyrolysis caused chemical structural changes in LLDPE due to LLDPE chain bond-breaking reactions, producing many smaller chemical compounds. Additionally, some oxidation happens, which is due to the oxygen content in the reactor. This study provides new insights into the LLDPE pyrolysis mechanism and the physical and chemical properties of the liquid resulting from the pyrolysis process.