Thermal Degradation Of Polystyrene Research Articles

Kinetics Study on Thermal Degradation of Polystyrene and Sulfonated Polystyrene from Styrofoam Waste

This research studied kinetics of thermal degradation of polystyrene (PS), and sulfonated polustyrene (sPS) which were synthesized from styrofoam waste. The thermal study was conducted by thermogravimetric analysis (TGA) at various heating rate of 10, 15, 20 and 25 dpm. The kinetics parameters were determined by Coats Redfern (CR), Friedman (FM), Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) models. TGA result found that PS has range thermal stability of 274 – 415 oC, but sPS has range thermal stability of 175 – 582 oC. Kinetic study to PS shows that the activation energy increases by the increasing of fraction conversion for all kinetics parameters with a regression value close to 1. While in sPS, the CR method shows an increase in activation energy value with an increasing fraction convertion. On the other hand, CR-FM-KAS and OFM methods obtained an increase in activation energy, then decreased at the fraction convertion above 0.6, and received negative activation energy. The kinetics model successfully explains the degradation of PS and sPS. In addition, the high thermal stability of sPS from styrofoam waste shows that this material has good potential as polymer electrolyte materials.

Synthesis of new methacrylates based on 6-phenylquinoline and their effect on the thermal degradation of polystyrene

In this work for the creation of polymers of special purpose six new quinolin-6-yl-phenylmethacrylates were synthesized by acylation of 3- and 4-hydroxyphenylquinolines with methacrylic acid chloroanhydride. The structure of the synthesized compounds was proved by spectral methods. The effect of new monomers as dopands on the polystyrene destruction was investigated. It was found that the investigated additives at covalent introduction into polystyrene weakly inhibit the process of its destruction, and additives containing nitro group - even contribute to its accelerated destruction.

Thermal degradation and thermal kinetic of SEBS block copolymer compatibilized PS/HDPE blends

The effect of styrene-ethylene/butylene-styrene block copolymer (SEBS) on the thermal degradation of polystyrene (PS)/high density polyethylene (HDPE) blends have been investigated. Polystyrene and (HDPE) are widely used thermoplastics, which have extensive application in everyday life. The main disadvantage of PS/PE systems is their poor miscibility which can be improved by adding compatibilizer. The blends were prepared by melt mixing in a twin screw extruder Haake Record 90. The behavior of the thermal degradation of PS/HDPE and PS/HDPE/SEBS blends has been investigated in inert nitrogen atmosphere by using thermogravimetric analysis (TGA) to obtain the degradation temperature and activation energy ( E a). The Ea for the PS/HDPE blends as well as for the PS/HDPE/SEBS blends was determined by the isoconversional Kissinger–Akahira–Sunose (KAS) method. The results indicated that the HDPE enhance thermal properties of the blends. The addition of SEBS in PS/HDPE blends increased the E a in all blends.

Thermal Degradation of Polystyrene (PS) Nanocomposites Loaded with Sol Gel-Synthesized ZnO Nanorods.

Thermal degradation of polystyrene/ZnO (PS/ZnO) nanocomposites was investigated in this study. PS/ZnO polymer nanocomposites were prepared by using ZnO nanorods as nanofillers that were prepared via the sol-gel route. The as-prepared ZnO nanoparticles showed nanocrystallites in rod-like shapes with a non-uniform hexagonal cross-section and diameter varying from 40 to 75 nm. PS/ZnO nanocomposites with ZnO nanoparticles content ranging from 0–3 wt% are prepared via the common casting method. Even dispersion for ZnO nanoparticles within as-prepared PS/ZnO nanocomposites was verified through SEM/EDX measurements. Thermal degradation of the samples was checked by using the thermogravimetric (TG) analysis and differential scanning calorimetry (DSC) under non-isothermal conditions and a constant heating rate of 10 °C min. The thermal stability of the nanocomposite is elevated compared to that of pristine PS due to the addition of the ZnO nanoparticles. The homogeneity of the PS/ZnO nanocomposites is verified by systematic increases in thermal degradation with increasing ZnO content. The characterization degradation temperatures at different weight loss percentages of ZnO nanoparticles increase at high ZnO wt%. Static activation energy of decomposing is based on TGA data. Activation energies showed some enhancement after the addition of ZnO nanorods into the PS matrix. Enhancing the thermal stability of PS with ZnO addition within the investigated ZnO concentration range is verified by TG, DSC results.

Thermal degradation of polystyrene composites. Part I. The effect of brominated polyepoxy and antimony oxide

Thermal degradation of polystyrene (PS) involving brominated polyepoxy (BA) and antimony oxide (PS/BE/Sb2O3) was studied systematically via direct pyrolysis mass spectrometry. Thermal decomposition of brominated polyepoxy was started by loss of end groups. The relative yields of high mass thermal degradation products of PS and the product distribution of brominated polyepoxy and antimony oxide were changed noticeably during the pyrolysis of PS/BE/Sb2O3 composite. Its thermal decomposition was initiated by the interactions of Sb2O3 with BE, and shifted to lower temperatures. Interactions of flame retardants with PS caused degradation of PS at lower temperatures to a certain extent. Loss of HBr and H2O, in the temperature region where main PS decomposition took place, confirmed chemical interactions between the flame retardants and PS.

Impact of brominated flame retardants on the thermal degradation of high-impact polystyrene

The degradation of flame retarded high impact polystyrene (HIPS) was examined by thermogravimetry coupled with mass spectroscopy (TG-MS) and compared with that of polystyrene (PS). While the fate of the flame retardant draws a lot of attention, its impact on polymer degradation has been the focus of very little investigation. Temperature change was shown not to affect the product distribution of the thermal induced PS degradation. However, the presence of a brominated flame retardant resulted in changes in the HIPS degradation mechanism, with a larger variation of by-products formed and changes in the product distribution over the investigated temperature range. The early release of a large quantity of bromine radicals from the flame retardant caused the polymer backbone to break at various points (radical induced degradation). While the thermal degradation of PS was inhibited by the recombination of macro radicals (the cage-effect), the recombination of macro radicals induced by bromine radicals was prevented by the fast diffusion of HBr. Pure PS produced mainly styrene by the depolymerisation of the polymer chain after the formation of macro radicals and some oligomers from backbiting/β-scission. Flame retarded HIPS produced various oligomers, many of which were not produced from pure PS. It is assumed that after backbiting, the tertiary radical was terminated by recombination with other radicals, and dimers and trimers were formed from styrene during secondary reactions. One important source of hydrogen for this process was the formation of aromatic compounds, which kept the residual char small.

Formal kinetics of polystyrene pyrolysis in non-oxidizing atmosphere

Previously reported kinetic data on polystyrene thermal degradation are inconsistent, and this may be a potential source of error in modeling the ignition and burning of the polymer composite materials containing polystyrene. To derive formal kinetic model of polystyrene thermal degradation, pyrolysis combustion flow calorimetry (PCFC) has been applied in this work. The heat release rate-temperature dependencies were measured at four heating rates of 0.25, 0.5, 1.0 and 2.0°C/s under nitrogen flow, and the kinetic parameters were derived by means of the model-free isoconversional method, the peak value method, the method of Kissinger and the model fitting non-linear optimization method. The single-step global reaction model has been demonstrated to have a constant activation energy of 168kJ/mol in a wide range of conversions. The autocatalytic reaction type has been established by evaluating the dependence of the kinetic function on the conversion derived from the measurement data. Thereby developed kinetic model has been validated against a variety of data sets including PCFC measurements made in this work, published TGA measurements, and isothermal experimental data. The model reproduced the experimental data to a reasonable accuracy for different temperature programs. The nth order reaction model was demonstrated to be unable to predict reaction rates for a range of different heating rates although it could be optimized for a single temperature program. Use of the nth order reaction has been shown to be a reason of obtaining unrealistically high apparent activation energies, reported for polystyrene degradation in the literature. The importance of processing multiple heating rate data to avoid misleading results is highlighted.

A New Kind of Renewable Energy: Production of Aromatic Hydrocarbons Naphtha Chemical by Thermal Degradation of Polystyrene (PS) Waste Plastic

Polystyrene (PS) waste plastic to renewable energy or naphtha grade fuel production through fractional distillation process was applied and PS liquefaction temperature range was 250?C - 430?C and fractional column temperature was 110?C - 135?C for naphtha grade fuel separation. The thermal degradation of PS waste plastic to renewable energy or naphtha grade chemical production was without adding any kind of cracking catalyst and without vacuum system. Polystyrene waste plastic is not bio-degradable and its can remain long period of landfill and creating gas emission for that reason its major cause climate change. For experimental purpose raw sample was use 1 kg of PS waste plastic and experiment was performed under Labconco fume hood and experiment was fully closed system, whole experiment was performed into stainless steel reactor. Produced fuel was analysis by gas chromatography and mass spectrometer, FT-IR and DSC. Analysis result indicate for fuel compounds chemical structure, compound band energy and enthalpy, delta H value. Produced fuel sulfur content less then environmental protection agency (EPA) level and fuel could be use for chemical feedstock refinery for further modification. By using this technology can reduce some foreign oil dependency and boost up renewable energy sector all over the world.

Thermal degradation of polystyrene in the presence of hydrogen by catalyst in solution

For the first time, low temperature degradation (170–240 °C) of polystyrene in benzene is carried out in the presence of hydrogen using iron(III) oxide catalyst. The effect of temperature, catalyst loading and polymer loading on degradation are studied in hydrogen atmosphere. Degradation is also carried out at different initial hydrogen partial pressure. The time dependent molecular weight is calculated using viscosity average method. It is found that the degradation is enhanced considerably in the presence of hydrogen and followed random degradation chain scission. A random degradation kinetic model of Kelen [Kelen T. Polymer degradation. New York: Van Nostrand Reinhold Company; 1983.] is used to estimate the degradation rate constants. Empirical correlations are proposed to account for the effect of catalyst loading and initial hydrogen partial pressure on degradation. The true thermal degradation rate constants are calculated using these proposed correlations at given catalyst loading and initial hydrogen partial pressure with varying temperature. The frequency factor and activation energy are also determined using Arrhenius equation considering the true thermal degradation rate constants.

The influence of temperature and the kind of the atmosphere on polystyrene thermal degradation

The influences of atmosphere and sample heating rate on the degradation temperature were estimated. Thermal degradation of polystyrene (PS) was carried out in a flow tubular furnace under isothermal conditions and in a thermogravimetric analyser under dynamic conditions. The experiments were performed in both a nitrogen and an air atmosphere. The thermal behaviour of tested polymer was determined on the basis of the thermogravimetric curves. The process of polystyrene thermal degradation in the tubular furnace was studied at the temperatures of 300°C, 400°C, 500°C, and 600°C for 30 min. The volatile and less-volatile thermal degradation products were analyzed using gas chromatography - mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FT-IR) methods. 64 degradation products were identified. Main of them were styrene and its dimer and trimer. In air atmosphere, the concentration of low molecular weight degradation products increases with the temperature while in nitrogen the maximal concentrations of some of them are reached at temp. 500°C.

The thermal degradation of nanocomposites that contain an oligomeric ammonium cation on the clay

The thermal degradation of polystyrene, high-impact polystyrene, ABS terpolymer, poly(methyl methacrylate), polypropylene and polyethylene nanocomposites has been studied using thermogravimetric analysis coupled to Fourier transform infrared spectroscopy, TGA/FT-IR. The nanocomposites that have been studied include immiscible, intercalated and exfoliated systems and the evolved gases do not depend upon the type of nanocomposite and are qualitatively similar to those of the virgin polymer. In the case of the styrenics, the presence of clay promotes the production of oligomer, rather than monomer. It is suggested that this change in evolved products may offer an explanation for why some polymers give large reduction in peak heat release rates while others give much smaller reductions. According to this notion, any polymer that undergoes degradation to produce both oligomer and monomer should give a large reduction in peak heat release rate.

A kinetic model for polystyrene (PS) pyrolysis reaction

A mathematical model for the pyrolysis reaction of polystyrene (PS) in a semi-batch reactor has been presented. The thermal degradation of PS was flexibly modeled by a combination of random and specific chain-end scissions. Numerical simulation was used to investigate the effect of operating conditions on the PS products spectrum, the results of which were validated by the experimental data. It was found that as the reaction temperature increased (decreased), the monomer fraction in the products became lower (higher) while the trimer higher (lower). No significant variation in the product composition was, however, observed while constant temperature was maintained. These results indicate the reaction temperature is an effective manipulated variable for the control of products composition of PS pyrolysis. The calculation of the optimum temperature trajectories through the optimization study can thus be of interest for achieving productivity enhancement in plastics pyrolysis processes.

Thermal Degradation of Polystyrene by Lewis Acids in Solution

The degradation of polystyrene in various Lewis acids [aluminum chloride, ferric chloride, boron triflouride etherate, and tin(IV) chloride] at different temperatures (75−125 °C) has been studied i...

Thermal degradation of polystyrene wastes in various solvents

Thermal polystyrene (PS) degradation was investigated in this work harnessing a high-pressure autoclave surrounded by a furnace. n-pentane, cyclohexane (CH), and toluene were used separately as the simplest representatives of aliphatic, cyclic, and aromatic solvents. One experiment was solventless. Without solvent at 400 °C, waste samples accrued the weight percentages of 32.0, 46.8, and 21.2 for the solid residue and the liquid and gaseous products respectively. Solvent employment is strongly recommended because it almost doubled the liquid yield while substantially reducing the solid residue to less than 5% and making the total conversion exceed 95%. A solvent:PS ratio of around 2:1 appeared to suffice. From 350 to 450 °C, the operating temperature had only a vague effect on this phase distribution. GC analyses identified methane, C2, C3, and C4 in the gaseous products. GC/MS results showed that cyclohexane usage rendered liquid products of ethyl benzene, methyl ethyl benzene, 1-phenyl naphthalene 1,1-bicyclohexyl, 2-cyclohexyl ethyl benzene. Toluene employment as solvent gave ethyl benzene, methyl ethyl benzene, 1-phenyl naphthalene propyl benzene, 1,2-dimethyl benzene.

Thermal degradation of polystyrene

Thermal degradation of plastic wastes offers the possibility of recovering energy and useful chemicals. Polyethylene and polypropylene pyrolysis have been discussed already in previous works (E. Ranzi, M. Dente, T. Faravelli, G. Bozzano, S. Fabini, R. Nava, V. Cozzani, L. Tognotti, J. Anal. Appl. Pyrol., 40–41 (1997) 305–319 and T. Faravelli, G. Bozzano, C. Scassa, M. Perego, S. Fabini, E. Ranzi, M. Dente, J. Anal. Appl. Pyrol., 52 (1999) 87–103). This paper aims to develop a detailed kinetic model of polystyrene thermal degradation. The predictions of overall rates of degradation and volatile product distribution are compared with experimental results obtained by different authors at different pressure and temperature conditions. In order to reduce the computing times required by the numerical integration of the kinetic model, a flexible lumping procedure has also been introduced.

Thermal degradation of polystyrene produced by nitroxide-controlled radical polymerization

Although the controlled free radical polymerization brings great advantages, a knowledge of the thermal stability of the products is important for industrial processes. For polystyrene prepared by nitroxide-controlled free radical polymerization (macroinitiator PSN), a first step of mass loss takes place in thermogravimetric analysis (TGA) at temperatures between 180 and 280°C. The temperatures of the first step and the value of the first step mass loss are dependent on the molecular weight and the terminator concentration. Detailed stepwise pyrolysis leads to the assumption that there are two parallel reactions for terminator removal. The results of stepwise pyrolysis show the scission of the polystyrenenitroxide (PSONR) bond followed by a weak depolymerization proceed from a secondary macroradical as one of the reactions at lower temperatures. With increasing temperature the contribution of the homolysis of the PSONR bond rises.

Thermal degradation of monodisperse polystyrene in bean oil

Thermal degradation of monodisperse polystyrene (PS) in bean oil was investigated in the temperature range of 305–350°C. The degradation products were identified by means of gel permeation chromatography (GPC) and Fourier transform infrared spectrometry (FTIR). A significant feature for the investigated system was that PS in the presence of bean oil thermally degraded into larger fragments of the polymer chain instead of monomer or oligomers which are usually generated in the direct thermal degradation. The average molecular weights of degradation products of PS decreased and the polydispersity indexes ( M w/ M n) increased but did not exceed 2 as the reaction time increased. The kinetics of the degradation reaction was also examined based on the GPC measurements. The results revealed that the degradation of PS in bean oil was a first order reaction and the energy of activation for chain scission was 215 kJ mol −1. The thermal degradation of PS in bean oil is believed to be a random chain scission process involving radical intermolecular transfer between bean oil and intermediate macroradicals of PS.

Kinetics of the Thermal and Thermo-Oxidative Degradation of Polystyrene, Polyethylene and Poly(propylene)

The thermal degradations of polystyrene (PS), polyethylene (PE), and poly(propylene) (PP) have been studied in both inert nitrogen and air atmospheres by using thermogravimetry and differential scanning calorimetry. The model-free isoconversional method has been employed to calculate activation energies as a function of the extent of degradation. The obtained dependencies are interpreted in terms of degradation mechanisms. Under nitrogen, the thermal degradation of polymers follows a random scission pathway that has an activation energy ≈200 kJ·mol–1 for PS and 240 and 250 kJ·mol–1 for PE and PP, respectively. Lower values (≈150 kJ·mol–1) are observed for the initial stages of the thermal degradation of PE and PS; this suggests that degradation is initiated at weak links. In air, the thermoxidative degradation occurs via a pathway that involves decomposition of polymer peroxide and exhibits an activation energy of 125 kJ·mol–1 for PS and 80 and 90 kJ·mol–1, for PE and PP respectively.

Effect of Porous and Nonporous Carbonaceous Substrates on Polystyrene Thermal Degradation during Fast CO2 Laser Heating

To investigate the effect of porosity on elution of volatiles from a devolatilizing coal particle under pulverized coal combustion (PCC) type heating rate conditions, polystyrene was doped into porous model char (Spherocarb) particles and also coated on the surface of nonporous model char (Glassy Carbon) particles. Particles of approximately 80 μm (± 10 μm) diameter were then individually handpicked. These 80 μm diameter particles were heated to a temperature in the range of 1200−2000 K in 32 ms by means of two converging CO2 laser beams. The eluted products were analyzed by combined gas chromatography/mass spectrometry (GC/MS). The evolved product information was used to construct yield curves. These yield curves were compared to a simple first-order rate law prediction. It was observed that while the styrene yield profile was predicted satisfactorily in the case of nonporous Glassy Carbon, styrene evolution rates were approximately four times slower than predicted in the case of porous Spherocarb. Also, the ratio of secondary pyrolysis products of polystyrene (benzene, toluene, etc.) to a primary pyrolysis product (styrene) was approximately four times higher in the case of Spherocarb than in the Glassy Carbon case. Both findings strongly suggest the presence of transport limitations in porous Spherocarb under PCC-type heating rate conditions.

Thermal degradation of polystyrene, poly(1,4-butadiene) and copolymers of styrene and 1,4-butadiene irradiated under air or argon with 60Co- γ-rays

60Co- γ-irradiated samples of polystyrene (PSt), poly(1,4-butadiene), (PBD), and two poly(styrene-co-butadiene)s containing 25 and 75% BD were subjected to thermogravimetric analysis (TGA), in the presence and absence of O 2. In the case of PSt the irradiation caused a significant shift in T onset, the onset temperature for mass loss, to higher temperatures, whereas in the cases of the BD-containing polymers irradiation caused a decrease in T onset (oxic irradiation) or had little or no effect on T onset (anoxic irradiation). The amount of non-volatile residue formed in the cases of BD-containing polymers was augmented by γ-irradiation. The improved thermal stability of PSt is attributed to radiation-generated unsaturations acting as depolymerization retardants and/or agents in thermal crosslinking. Radiation-induced crosslinks do not affect the thermal behavior of PSt. In the cases of BD-containing polymers the thermal behavior is predominated by reactions of the carbon–carbon double bonds (crosslinking and cyclization). Radiation-induced chemical alterations, therefore, play a minor role during the thermal decomposition.