Cornelia Vasile

Vacuum pyrolysis of PVC I. Kinetic study

Abstract Vacuum pyrolysis of PVC has been studied emphasizing two aspects: the kinetics of PVC pyrolysis reactions and the yields of pyrolysis products. The purpose of the kinetic study is to identify each apparent reaction involved in PVC pyrolysis. Three stages of weight loss have been evidenced by TG analysis during PVC decomposition both under vacuum and in nitrogen atmosphere, while in most previous studies carried out under similar conditions only two stages were detected. The corresponding temperature intervals of these three stages are: 200–320°C; 250–375°C and 375–520°C. Based on the TG results, a three-apparent-reactions model is proposed. Kinetic parameters and conversion factors have been calculated for each apparent reaction with this model including all three stages of decomposition. Some results are in good accordance with literature data. Bench scale PVC pyrolysis tests were carried out to collect the pyrolysis products from each single apparent reaction. These products were analyzed and a correlation with TG results was made in order to assign these results to a certain change of the PVC structure. These findings provide new insights into the PVC thermal decomposition and useful data for controlling the release of HCl during PVC pyrolysis have been made available.

Spectral Characterization of Eucalyptus Wood

The main difficulties in wood and pulp analyses arise principally from their numerous components with different chemical structures. Therefore, the basic problem in a specific analytical procedure may be the selective separation of the main carbohydrate-derived components from lignin due to their chemical association and structural coexistence. The processing of the wood determines some structural modification in its components depending on the type of wood and the applied procedure. Fourier transform infrared (FT-IR) spectrometry and X-ray diffraction have been applied to analyze Eucalyptus g. wood chips and unbleached and chloritebleached pulp. The differences between samples have been established by examination of the spectra of the fractions obtained by successive extraction (acetone extractives, acetone free extractive samples, hemicelluloses, and lignins) by evaluating the derivative spectra, band deconvolution, etc. The energy and the hydrogen bonding distance have been evaluated. The relationship between spectral characteristics and sample composition has been established, as well as the variation of the degree of crystallinity after pulping and bleaching. The integral absorption and lignin/carbohydrate ratios calculated from FT-IR spectra of the IR bands assigned to different bending or stretching in lignin groups are stronger in the spectrum of eucalyptus chips than those from brown stock (BS) pulp spectra because of the smaller total amount of lignin in the latter. FT-IR spectra clearly show that after chlorite bleaching the structure of the wood components is partially modified or removed. Along with FT-IR data, the X-ray results confirmed the low content of lignin in the pulp samples by increasing the calculated values of the crystalline parameters. It was concluded that FT-IR spectroscopy can be used as a quick method to differentiate Eucalyptus globulus samples.

Vacuum pyrolysis of commingled plastics containing PVC II. Product analysis

Vacuum pyrolysis of individual plastics including high density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP) and polystyrene (PS) has been performed at a final temperature of 500°C and under a total pressure of 2 kPa. A PVC sample and a commingled plastic sample composed of HDPE/LDPE/PP/PS/PVC have been pyrolyzed in two consecutive steps at 360 and 520°C in order to separately trap HCl. A pyrolysis set-up consisting of a bench scale batch reactor with a condensation train was used to collect the pyrolysis products. The main gaseous and liquid products, including the chlorinated hydrocarbons, were identified by chromatography. Global and chlorine mass balances were performed. The yields and pyrolysis product composition from each single polymer were compared with those from the commingled plastics. At 520°C, 99.55 wt.% of the total chlorine was trapped as HCl corresponding to 4.6 wt.% in yield, on an original feedstock basis, followed by 62.0 wt.% wax, 31.1 wt.% oil, 1.0 wt.% gas and 1.2 wt.% solid char residue (loss was 0.1 wt.%). The pyrolysis oil contained 12 ppm Cl on a pyrolysis oil basis. This value was less than what was expected (153 ppm) from the theoretical values which were calculated when the individual polymers were pyrolysed. The chlorinated hydrocarbons formed during the pyrolysis of commingled plastics were different from those obtained during the thermal decomposition of pure PVC. However, the hydrocarbons produced in the oil fraction were similar to those identified during the pyrolysis of the single plastics.

Vacuum pyrolysis of commingled plastics containing PVC I. Kinetic study

Abstract Thermal decomposition of commingled plastics comprising high and low density polyethylene, polystyrene, polypropylene and poly(vinyl chloride) was investigated under vacuum conditions by dynamic thermogravimetric analysis in the temperature range of 25–600°C. The mixtures were representative of the major polymeric materials found in a municipal plastic waste (MPW) stream. The study focused on the role of each polymer in the stabilization or destabilization of other interacting plastics, as well as the fate of chlorine produced from PVC. First, the decomposition of each single plastic was investigated. Then the binary combination of all above polymers and finally the multicomponent mixture similar to a MPW sample were studied. Two approaches have been applied to study the interaction between components in the commingled plastics. The first approach involved a comparison of the experimental curve of the decomposition of the mixture with a calculated non-interacting component decomposition curve based on the behavior of the individual polymers. The second approach involved a comparison of the kinetic parameters of each plastic in the mixture as determined by two different methods: (1) fitting the single polymer decomposition curve and (2) fitting the peak corresponding to the pyrolysis of one particular polymer on the mixture pyrolysis curve. The results obtained indicate that some interactions occurred during MPW pyrolysis, mainly at high temperatures (>375°C). PS and PVC appear to be the plastics responsible for the interactions through their intermediate pyrolysis products. The chlorine from PVC in the mixture is released almost completely before 375°C, when the conversion of the MPW to pyrolysis products has reached ca. 13%.

Thermal and catalytic decomposition of mixed plastics

Abstract The decomposition of a polymer mixture containing 24 wt.% HDPE, 39 wt.% LDPE, 21.5 wt.% IPP, 10 wt.% PS, 4 wt.% ABS and 1.5 wt.% PET (composition close to that frequently met in municipal plastic waste without PVC), over HZSM-5 and orthophosphoric acid modified (PZSM-5) zeolite catalysts has been comparatively studied. The reaction products were analyzed by chromatographic, IR and 1 H-NMR spectroscopic methods as well as by standard methods, which are frequently used in the petrochemical laboratories. Catalytic decomposition increased the amount of gaseous products, lowered the condensate, and changed their composition with respect to the non-catalytic at the same pyrolysis temperature. The gaseous products contained a large C 3 fraction, while the liquid products contained mainly aromatic hydrocarbons. PZSM-5 catalyst promoted the formation of α-alkyl substituted and condensed ring aromatics hydrocarbons while HZSM-5 produced more isomeric compounds. The global yields of the reaction products from the catalytic decomposition at 400–450°C over both catalysts were close to that obtained by non-catalytic decomposition at 600–700°C temperature range. The composition of all products was dependent on the catalyst activity and acidity.

Lignin/epoxy composites

Abstract This paper presents some possibilities for the use of lignin/epoxy resins in blends and composites with epoxy resins. A compatibility study was carried out by optical and electron microscopy, viscosimetric determinations and thermo-optical analysis in order to establish optimum synthesis conditions of molding mass (cast resins). Lignin/epoxy composites including various fillers (lead soap, alum earth, talc, chalk, sand, trihydrate aluminium oxide, glass fibers), plasticizer (dibutylphthalate and polyester C6) and pigments (iron-oxide and titanium dioxide) have been obtained. Lignin/epoxy composites are characterized by good dielectric, mechanical and adhesive properties. These composite materials can be used in the electronics industry.

Pyrolysis of the tetra pak

This study deals with pyrolysis of tetra pak which is widely used as an aseptic beverage packaging material. Pyrolysis experiments were carried out under inert atmosphere in a batch reactor at different temperatures and by different pyrolysis modes (one- and two-step). The yields of char, liquid and gas were quantified. Pyrolysis liquids produced were collected as three separate phases; aqueous phase, tar and polyethylene wax. Characterization of wax and the determination of the total amount of phenols in aqueous phase were performed. Chemical compositions of gas and char products relevant to fuel applications were determined. Pure aluminum can be also recovered by pyrolysis.

Structural analysis of photodegraded lime wood by means of FT-IR and 2D IR correlation spectroscopy

In this study the weathering behavior of lime wood (Tillia cordata Mill.) has been examined using FT-IR and 2D IR correlation spectroscopy, which evidenced chemical changes induced by exposure to weathering conditions. It was showed that lignin is most sensitive component to the photodegradation processes as indicated by considerable decreases in the intensities of the characteristic aromatic lignin band at 1505cm(-1) and other associated bands. By 2D correlation spectroscopy has been demonstrated that the moment of CO from carboxyl and acetyl groups in hemicelluloses is changing first, followed by the CC of aromatic skeletal, CO in non-conjugated ketones, carboxyl groups and lactones, absorbed O-H and conjugated C-O groups in quinones. The carbonyl formation corresponded well with lignin degradation, indicating a close relationship between them. Comparing the rate of carbonyl formation and lignin decay clearly showed that the former is remarkably higher than the latter, indicating the formation of carbonyl bands at 1738cm(-1) probably resulted from not only lignin oxidation but also from reactions occurring in other components of the wood. Quinine formation is combined with the decay of aromatic structures and the formation of conjugated carbonyl groups.

On the compatibility of the IPP/PA6/EPDM blends with and without functionalized IPP I. Thermo-oxidative behaviour

Abstract Binary isotactic polypropylene (IPP)/polyamide 6 (PA6) and ternary IPP/PA6/ethylene–propylene diene terpolymer (EPDM) blends in various ratios were obtained in a Haake Rheocord mixer. Processing behaviour was changed in the presence of IPP functionalized with bismaleimide (BMI), maleic anhydride (MA) and acrylic acid (AA) as reactive compatibilizing agents. The thermal and thermo-oxidative behaviour of blends was studied by differential scanning calorimetry and thermogravimetry. The functionalized IPPs modify the crystallinity degree and the decomposition behaviour of both IPP and PA6 as a result of chemical reactions of functional groups with those of the PA6. The changes depend on the IPP/PA6 or IPP/PA6/EPDM ratio, the chemical nature and amount of the functionalized IPP. On the basis of the processing and thermal data one can conclude that the compatibilizing agent effect increases in the following order: IPP-AA

Polymers with pendent functional groups. V. Thermooxidative and thermal behavior of chloromethylated polysulfones

Abstract The first step of the thermooxidative and thermal decomposition of some chloromethylated polysulfones (CMPSF) with various degrees of substitution has been studied by thermogravimetry (TG) and thermal volatilization analysis (TVA). A step occurring at lower temperatures 260–370°C is particular for halomethylated polysulfones because the polysulfone (PSF) is thermally stable in this temperature range (its first decomposition step occurs from 400 to 550°C). The higher the degree of substitution, the lower the degradation temperature and a better separation of the processes was found. The thermal decomposition products collected were analyzed by IR spectroscopy and elemental analysis. According to our TG and TVA results and literature data , it can be proposed that –CH2Cl groups react at low temperatures giving cross-linked polymer and gas or liquid products. The thermal characteristics of this process depend on the chlorine content of the sample and explain undesirable cross-linking that could take place during the synthesis of the chloromethylated polysulfones.