Degradation Of Polystyrene Research Articles

Solid‐phase photocatalytic degradation of polystyrene with TiO2/Fe(St)3 as catalyst

AbstractA novel photodegradable TiO2‐Fe(St)3‐polystyrene (TiO2‐Fe(St)3‐PS) nanocomposite was prepared by embedding TiO2 and Fe(St)3 into the commercial polystyrene. Ferric stearate was added into polymer as cocatalyst in order to improve the dispersion in polystyrene and photocatalytic efficiency of TiO2 nanoparticles. Solid‐phase photocatalytic degradation of the TiO2‐Fe(St)3‐PS nanocomposite was carried out in an ambient air at room temperature under ultraviolet lamp. The properties of TiO2‐Fe(St)3‐PS composite film were compared with that of the pure PS film and the TiO2‐PS composite film, through weight loss monitoring, scanning electron microscope, gel permeation chromatogram, and FTIR spectroscopy. The photodegradation efficiency of TiO2‐Fe(St)3‐PS composite film was higher than that of the pure PS film and the TiO2‐PS composite film under the UV light irradiation. The average molecular weight (Mw) of TiO2‐Fe(St)3‐PS composite film decreased 63.08%, and the number of average molecular weight (Mn) decreased 79.49% after UV light irradiation for 480 h. Photo‐oxidation leads to an increase in the low molecular weight fraction by chain scission, thereby facilitating biodegradation. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

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.

Reactive melt blending of PS‐POSS hybrid nanocomposites

AbstractHybrid nanocomposites of polystyrene (PS) and methacryl phenyl polyhedral oligomeric silsesquioxane (POSS) were synthesized by reactive melt blending in the mixing chamber of a torque rheometer using dicumyl peroxide (DCP) as a free radical initiator and styrene monomer as a chain transfer agent. The effects of mixing intensity and composition on the molecular structure and morphology of the PS‐POSS hybrid nanocomposites were investigated. The degree of POSS hybridization (αPOSS) was found to increase with the POSS content, DCP/POSS ratio, and rotor speed. For the PS‐POSS materials processed in the absence of styrene monomer, an increase in the αPOSS led to a reduction in the molecular weight by PS chain scission, as a consequence of the free radical initiation. On the other hand, the use of styrene monomer as a chain transfer agent reduces the steric hindrance in the hybridization reaction between POSS and PS, enhancing the degree of POSS hybridization and avoiding PS degradation. The PS‐POSS morphology consists of nanoscale POSS clusters and particles and microscale crystalline POSS aggregates. PS‐POSS with higher αPOSS values and lower amounts of nonbound POSS showed improved POSS dispersion, characterized by smaller interfacial thickness (t) and greater Porod inhomogeneity lengths (lp). The processing‐molecular structure–morphology correlations analyzed in this study allow the POSS dispersion level in the PS‐POSS materials to be tuned by controlling the reactive melt blending through the choice of the processing conditions. These insights are very useful for the development of PS‐POSS materials with optimized performance. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Thermo-Catalytic Versus Thermo-Chemical Recycling of Polystyrene Waste

Degradation of polystyrene was carried out thermally and thermo-chemically in order to compare between the conversion of polystyrene in both cases. The catalyzed thermal degradation was achieved without solvents in an autoclave at pressure range 20–50 bar and temperature range 300–400 °C in presence of 1 % Al2O3 as a catalyst. The thermo-chemical degradation was achieved by two solvents namely, supercritical cyclohexane and supercritical ethyl cyclohexane under the same reaction conditions. It was found that conversion of polystyrene increased in the thermo-chemical process than in thermal process. Furthermore, it was found that the conversion process increases with rising temperature and pressure. It also was found that high molecular-weight compounds decreased but oligomers and monomers increased with rising temperature. Polystyrene rapidly degraded after reaching a prescribed temperature of 400 °C, the degree of degradation was nearly about 95 % after 1 h in presence of ethyl cyclohexane, 89 % in presence of cyclohexane and about 81 % only in absence of the solvent (thermal degradation).

FeCl2‐Promoted Cleavage of the Unactivated CC Bond of Alkylarenes and Polystyrene: Direct Synthesis of Arylamines

Ironing it out: an efficient and convenient nitrogenation strategy involving C-C bond cleavage for the straightforward synthesis of versatile arylamines is presented. Various alkyl azides and alkylarenes, including the common industrial by-product cumene, react using this protocol. Moreover, this method provides a potential strategy for the degradation of polystyrene.

Caracterização viscosimétrica de nanocompósitos híbridos PS/POSS

Nanocompósitos híbridos de poliestireno (PS) e poliedros oligoméricos silsesquioxanos (POSS) com diferentes composições e graus de hibridização foram obtidos por processamento reativo no estado fundido utilizando-se peróxido de dicumila (DCP) como iniciador, na presença ou não de estireno como agente de transferência de radical. Os materiais foram caracterizados viscosimetricamente por cromatografia de permeação em gel (GPC) usando detecção tripla por espalhamento de luz, viscosimetria e índice de refração. As amostras PS/POSS processadas com estireno apresentaram maiores valores de massa molar ponderal média (Mw) e menores valores de polidispersão (Mw/Mn), devido ao maior grau de conversão da reação de hibridização do PS-POSS (28-40%) e do menor grau de degradação (cisão) das cadeias do PS, quando comparadas com amostras PS/POSS processadas sem estireno nas quais o grau de conversão ficou em torno de 24-28%. Para os sistemas PS e PS/POSS em solução com THF, os parâmetros da equação de Mark-Houwink-Sakurada (MHS), α ≅ 0,7 e log K ≅ -3,5 a -3,9 e os valores dos parâmetros de interação polímero-solvente, χij ≅ 0,49, não apresentaram diferenças significativas com relação aos tamanhos moleculares. Por outro lado, essas diferenças de tamanhos moleculares foram caracterizadas por uma função cumulativa da fração mássica de cadeias em função da distância média quadrática entre pontas de cadeia (< r² >0½).

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.

Non-isothermal thermogravimetry, differential scanning calorimetry and chemiluminescence in degradation of polyethylene, polypropylene, polystyrene and poly(methyl methacrylate)

The degradation of pure polymers such as polyethylene, polypropylene, polystyrene and poly(methyl methacrylate) in nitrogen and oxygen was characterized by means of non-isothermal thermogravimetry, chemiluminescence and differential scanning calorimetry. The link between the results of the different methods based on Bolland Gee scheme of polymer oxidation is described. From the set of parameters determined from the thermogravimetry, the rate constants based upon the sum of several temperature dependent first-order processes were calculated and compared with those obtained by an iso-conversional method derived for several heating rates. Competition between propagation of oxidation and depolymerisation to monomer is proposed to explain the differences in kinetic behaviour of the examined polymers.

Catalytic Degradation of Polystyrene: Modeling of Molecular Weight Distribution

AbstractTwo of the most abundant polymers in household waste streams, PS and PE, may be recycled by compatibilization through a Friedel‐Crafts alkylation. This reaction produces a graft copolymer PE‐g‐PS that improves the properties of the blend, but simultaneously degrades PS chains. Since the copolymer efficiency as a compatibilizer depends both on the molecular weight and MWD of its two blocks, the operating conditions for the copolymer synthesis must be carefully tuned. To aid in this task, we present a preliminary mathematical model that focuses on the effect of the catalyst and cocatalyst of the Friedel‐Crafts alkylation on the MWD of the PS chains. The model's predictions are shown to agree with experimental data. magnified image

Effect of Calcination Method on the Catalytic Degradation of Polystyrene using Al2O3 Supported Sn and Cd Catalysts

Effect of Calcination Method on the Catalytic Degradation of Polystyrene using Al2O3 Supported Sn and Cd Catalysts

Detection of organic products of polymer pyrolysis by thermogravimetry-supersonic jet-skimmer time-of-flight mass spectrometry (TG-Skimmer-SPI-TOFMS) using an electron beam pumped rare gas excimer VUV-light source (EBEL) for soft photo ionisation

A commercial thermogravimetry—supersonic jet-skimmer quadrupole mass spectrometer system (TG-Skimmer-QMS, Netzsch GmbH, Germany) was successfully converted for soft single photon ionisation time-of-flight mass spectrometric (SPI-TOFMS) detection of organic compounds. VUV light for SPI was generated by an electron beam pumped argon excimer light source (EBEL; E photon = 9.8 eV). Furthermore, the versatility of the system was conserved, as high temperature TG and DSC measurements as well as electron ionisation mass spectrometry for the detection of inorganic compounds are still possible. The new system was tested with two polymers and a hydrocarbon mixture (diesel). It was demonstrated that aliphatic and aromatic organic compounds can be detected without fragmentation. Thus the system allows the recording of a readily interpretable organic signature of, e.g. thermal polymer decomposition. The thermal degradation of polystyrene shows a rich signature of the monomer, some oligomers and minor products of irregular cleavings of carbon chains. Polycarbonate exhibits a thermal decomposition fingerprint which is dominated by products of bisphenol A. The bisphenol A monomer, however, is also detectable.

NMR relaxation reveals modifications in rubber phase dynamics during long-term degradation of high-impact polystyrene (HIPS)

The microstructure of rubber-modified polystyrene after thermal ageing at 90 °C and multiple extrusion was analyzed by time-domain nuclear magnetic resonance (TD-NMR) in a non-destructive manner. The transverse magnetization decay behaviour observed in TD-NMR was related to the total rubber fraction and its cross-linking density. The data reveal different mechanisms of long-term rubber degradation in high-impact polystyrene (HIPS) during thermo-oxidation and multiple processing: Multiple processing causes a slight increase in the cross-linking density of the rubber phase, without appreciably altering the total amount of rubber fraction. Thermo-oxidation is accompanied by a significant overall decrease of the rubber fraction, an increase of the cross-linking density, and a pronounced increase of the non-crosslinked fraction (chain ends and fragmented segments). The NMR results correlate well with spectroscopic observations and moderately with macroscopic mechanical properties.

Functionalization of styrenic polymer through acylation and grafting under microwave energy

In this study, a new synthetic methodology for the functionalization of polystyrene (PS) has been developed, in which maleic anhydride was used in the presence of zinc oxide as catalyst and microwave energy was used as power source. A mechanism for the acylation reaction is proposed. The effect of reaction conditions on the degree of functionalization of PS was investigated. A subsequent reaction with diisopropyl fumarate/benzoyl peroxide was used to produce a graft copolymer. The polymers were identified and characterized by Fourier transform infrared spectroscopy, ultraviolet (UV) spectroscopy, proton nuclear magnetic resonance and size exclusion chromatography using double detection to confirm the structure of the macromolecules. In addition, the effect of acylation and grafting into PS on the corrosion resistance of steel surfaces were studied. The results show high efficiency of the acylation and grafting reactions under microwave conditions, with no PS degradation. Improvement in the corrosion resistance of both acylated and graft polymers suggest that they are suitable for use as protective coatings. A new synthetic methodology has been carried out for functionalized polystyrene through acylation and grafting under microwave energy. Improves in the corrosion resistance of both products suggest a good capacity as protective coating.

Mathematical modeling of the graft reaction between polystyrene and polyethylene

Polystyrene (PS) and polyethylene (PE) are two major components of household plastic waste whose blends are immiscible. Recycling them together is an attractive option that requires a compatibilization process to improve the blend mechanical properties. If a PE/PS copolymer is added or formed in situ, it may act as compatibilizer. The structure and molecular properties of this copolymer are key factors to assure its effectivity as a compatibilizer. In this work, we study the graft copolymerization reaction between polystyrene and polyethylene using the catalytic system composed of AlCl3 and styrene. We develop a model of this process which considers that PE/PS grafting and PS degradation occur simultaneously. We propose a kinetic mechanism for the whole process and apply the method of moments to solve the mass balance equations. The model is able to calculate average molecular weights as well as the amount of grafted PS. It accurately describes the available experimental data, constituting a valuable tool for simulation and optimization purposes.

Comparative Kinetics Study of the Thermal and Thermo-Oxidative Degradation of a Polystyrene-Clay Nanocompozite by TGA and DSC

The methods of thermogravimetry (TGA) and differential scanning calorimetry (DSC) have been used to study the thermal and thermo-oxidative degradation of polystyrene (PS) and a PS-clay nanocomposite. An advanced isoconversional method has been applied for kinertic analysis. Introduction of the clay phase increasers the activation energy and affects the total heat of degradation, which suggests a change in the reaction mechanism. The obtained kinetic data permit a comparative assessment of the fire resistance of the studied materials.

Effect of Metal Oxide Catalysts on Degradation of Waste Polystyrene in Hydrogen at Elevated Temperature and Pressure in Benzene Solution

Degradation of waste polystyrene is carried out in presence of hydrogen using several metal oxide catalysts at elevated temperature and pressure for recycling. Benzene is used as a solvent for degradation. Initial hydrogen pressure in the autoclave is kept at 7.0 kg/cm2 (g) and polystyrene degradation is carried out at 240 °C. After degradation, degraded polystyrene residue is separated and analyzed by Fourier transform infra red (FTIR) spectroscopy whereas filtrate is analyzed by gas chromatography (GC) for finding the degradation mechanism of polystyrene. Degradation rate is enhanced in presence of hydrogen and time dependent weight average molecular weight of degraded polystyrene is determined using viscosity method. Degradation rate constants for the different catalysts are calculated based on the proposed degradation mechanism. Alkali metal oxide catalyst shows higher reactivity towards polystyrene degradation as compare to the transition metal oxide catalyst i.e., degradation rate constant decreases with the increase in electro negativity of metal element of the catalyst. Though manganese (IV) oxide is a transition metal catalyst, but shows higher reactivity due to its reduction towards stable manganese (II) oxide under degradation environment. Finally, degradation rate constant of polystyrene is correlated with the catalyst activity i.e., electro negativity of metal element in the catalyst.

Surface‐enhanced Raman scattering from polystyrene on gold clusters

AbstractSurface‐enhanced Raman scattering (SERS) constitutes a spectroscopic method of rapidly growing importance, and polystyrene is a widely used compound of great industrial importance. In this work, SERS data were obtained from polystyrene samples prepared by vapor deposition of gold and plasma‐induced polymerization of styrene gas. A thorough examination of this data is presented. The relationships between sample preparation parameters, gold‐cluster morphology, and SERS intensity were elucidated. Using Wilson's notation, vibrations were assigned to all bands between 250 and 1750 cm−1 in the ordinary Raman and SERS spectra of polystyrene. The correct assignment of these bands would be a significant achievement because they have been controversial in the literature for ∼30 years. Our assignments were made by reviewing the literature and comparing the assignments found there to spectral data acquired during this study; they were confirmed using density functional theory (DFT) calculations performed on the styrene monomer. The orientation of polystyrene's phenyl ring, relative to the gold surface, was determined. It has been suggested that reactions involving silver catalyze polystyrene degradation during SERS, but we found that silver is not necessary for the degradation to occur. Copyright © 2009 John Wiley & Sons, Ltd.

Chain Degradation during Dissolution of Polymer-Fullerene Nanocomposites as a Result of Interaction of Entangled Polymer Matrix with the Filler

Chain degradation of poly(α-methylstyrene) and polystyrene during dissolution of their nanocomposites with fullerene C60 in solvents of different quality with respect to fullerene was studied in detail by size exclusion chromatography and UV spectroscopy. Chain ruptures have been shown to arise during swelling of composites but only for samples with entangled polymer matrix. The data obtained confirm that the hindered mobility of chains because of interaction of the entangled matrix with fullerene is the only cause of degradation. Chain rupture leads to radical depolymerization accompanied by covalent binding of fullerene with the chain fragments, which results in changing of the polymer matrix structure. Chain degradation indicates deterioration of the mechanical properties of the polymers in the presence of C60. The possibility of chain degradation in polymer-filler nanocomposites under deformation with the simultaneous observation of an apparent reinforcement effect because of the addition of filler in the polymer matrix is discussed.

Abiotic and biotic degradation of oxo-biodegradable foamed polystyrene

An alternative for improving the degradability of polyolefins and polystyrene is the addition of pro-oxidant substances to their formulations. The materials obtained are then called oxo-biodegradable. This work aimed to assess the biotic and abiotic degradation of atactic polystyrene (PS), utilising as test material foamed PS plates used in the manufacture of trays, formulated with Co- and Mn-based pro-oxidant additives. The plates were exposed to artificial weathering (ultraviolet radiation and heat) and were periodically analysed for changes in structural properties. The oxidised surface residues detached from the samples were incubated in a stabilised compost of urban waste (58 °C) or in an aqueous mineral medium (25 °C), the latter being inoculated with urban waste compost and also with a microbial consortium. It was found that the molar masses of the eroded materials from the pro-oxidant activated samples were significantly lower than the initial sample molar masses, with simultaneous incorporation of oxygen into the chains during the accelerated weathering. These samples underwent biodegradation and gave mineralisation values of 2–5% over 2–3 months of incubation in compost and perlite or in mineral aqueous medium. Biodegradation of the residues from the samples not containing pro-oxidant additives was also observed, but at levels which were lower than those obtained for oxo-biodegradable samples.

Design of Chemically Activated Polymer Microwells by One-Step UV-Lithography for Stem Cell Adhesion

A novel method to produce sub-microwalled chemically activated polymer microwells by one-step UV-lithography under ambient conditions which are selectively coated with gelatin is introduced. The dimensions as well as the shape of the resulting polystyrene structures are both tunable merely by the irradiation time through one and the same mask. It is shown that the UV-irradiation initiates three effects at those surface areas which are not covered by the mask: (i) oxidation, (ii) cross-linking, and (iii) degradation of polystyrene. The superposition of those effects results in the formation of microscaled, oxidized polymer wells separated by polymer walls, whereas the polymer walls are formed below the mask structures. Topographical changes induced by the UV-irradiation are investigated by atomic force microscopy after different irradiation times. It is shown by X-ray photoelectron spectroscopy and ellipsometric investigations that the chemical composition of the irradiated areas and the degradation of polystyrene reach an equilibrium state after an irradiation time of 10 min. The lateral distribution of the cross-linked and oxidized and of the nonmodified polystyrene after irradiation was determined by fluorescence microscopy and time-of-flight secondary ion mass spectrometry. After the irradiated samples were treated with gelatin solution, it was found that stem cells selectively attach to the irradiated areas. This is due to the selective immobilization of the gelatin on the irradiated polymer areas, which was proved by X-ray photoelectron spectroscopy experiments.