Pyrolysis Mass Spectrometric Analysis of styrene butadiene block and random copolymers

Cataloged from PDF version of article.Direct pyrolysis mass spectrometric analysis of a styrene-butadiene-styrene block copolymer indicated that thermal decomposition of each block shows a resemblance to the related homopolymer, giving a possibility of differentiation of blocks. However, the random analog, the styrene butadiene rubber, degraded in a manner that is somewhat in between in nature of the thermal characteristics of both homopolymers. This technique shows promise to differentiate thermal behaviors of each sequence in block polymers if any exist. Indirect pyrolysis mass spectrometric analysis gave no clear evidence for differentiation of the nature and the composition of the copolymers. © 1997 Elsevier Science Ltd. All rights reserved

Utilization of temperature kinetics as a method to predict treatment intensity and corresponding treated wood quality : durability and mechanical properties of thermally modified wood

Wood heat treatment is an attractive alternative to improve decay resistance of wood species with low natural durability. However, this improvement of durability is realized at the expense of the mechanical resistance. Decay resistance and mechanical properties are strongly correlated to thermal degradation of wood cells wall components. Mass loss resulting from this degradation is a good indicator of treatment intensity and final treated wood properties. However, the introduction of a fast and accurate system for measuring this mass loss on an industrial scale is very difficult. Nowadays, many studies are conducted on the determination of control parameters which could be correlated with the treatment conditions and final heat treated wood quality such as decay resistance. The aim of this study is to investigate the relations between kinetics of temperature used during thermal treatment process representing heat treatment intensity, mass losses due to thermal degradation and conferred properties to heat treated wood. It might appear that relative area of treatment temperature curves is a good indicator of treatment intensity. Heat treatment with different treatment conditions (temperature-time) have been performed under vacuum, on four wood species (one hardwood and three softwoods) in order to obtain thermal degradation mass loses of 8, 10 and 12%. For each experiment, relative areas corresponding to temperature kinetics, mass loss, decay resistance and mechanical properties have been determined. Results highlight the statement that the temperature curves’ area constitutes a good indicator in the prediction of needed treatment intensity, to obtain required wood durability and mechanical properties such as bending resistance and Brinell hardness.LERMaB is supported by the French National Research Agency through the Laboratory of Excellence ARBRE (ANR-12- LABXARBRE-01), the authors gratefully acknowledge this ai

Thermogravimetric and kinetic analyses of oil palm empty fruit bunch (OPEFB) pellets using the distributed activation energy model

The thermal degradation behaviour and decomposition kinetics of oil palm empty fruit bunch (OPEFB) pellets were investigated using a thermogravimetric analyser and the distributed activation energy model (DAEM). The OPEFB pellets were heated from 30°C to 1000°C at three different heating rates (5, 10, 20°C min-1) under a nitrogen atmosphere. The thermogravimetric-derivative thermogravimetric (TG-DTG) curves revealed that the non-isothermal decomposition of OPEFB pellets occurred in the following three stages: drying (35°C-175°C), active pyrolysis (200°C-370°C) and passive pyrolysis (370°C-1000°C), which resulted in the loss of moisture, volatile matter and char, respectively. The distributed activation energy model was subsequently used to determine the apparent activation energies (E) and pre-exponential factors (A), which ranged from 37.89 kJ mol-1 to 234.05 kJ mol-1 and from 2.05 × 102 min-1 to 3.54 × 1018 min-1, respectively, for conversions of α = 0.05-0.70 during the thermal degradation. The wide E and A distributions obtained from the kinetic analysis are attributed to the complex chemical reactions of pyrolysis. The kinetic analysis revealed the kinetic compensation effect (KCE), with the highest E and A values occurring in the range of α = 0.2-0.4. This result indicates that the active pyrolysis stage is the rate-determining step during the thermal decomposition of OPEFB pellets

Effect of composition and density on the ablative performance of phenolic-nylon

Composition and density effects on ablative performance of phenolic-nylo

Tyre profiling : development and evolution of forensic methodology

University of Technology, Sydney. Faculty of Science.The chemical analysis of tyres is not a routine part of forensic investigation. The use of tyres as evidence has been limited to comparison of the tread pattern. However, the tread pattern is not the only evidence that may be left behind by a tyre. When a tyre skids across a hard road surface such as bitumen or concrete, residue from the tyre may be left behind. It was the aim of this research to develop a method for the analysis of tyres and their residues, understand the amount of chemical variation in tyres, identify suitable methods for the collection of tyre residues from different road surfaces, and to classify tyre samples and identify the source of tyre residues. A suitable method for analysis was successfully developed using pyrolysis-gas chromatography/mass spectrometry. It was found that pyrolysis was best completed at 450 °C using a furnace type pyrolyser. Chemical variation was investigated in a single tyre, in tyres over time, in production batches, and between different models and sizes of tyres from the same manufacturer. Small variations were found within a single tyre and in tyres over time. Greater variation was observed in both the same and different production batches, and between different model tyres and different size tyres. Three different collection techniques were investigated - picking, adhesive tape, and swabbing. Picking was found to be the most suitable technique to use on a concrete road with gravel aggregate, while a fingerprint lift was found to be the most suitable technique on a bitumen road surface. Swabbing was found to be an unsuitable technique. Six replicate analyses were used to catalogue changes in the chemical composition between the tyre and the residue. Numerous changes were observed such that only a limited number of signals from the chromatogram could be used for identification purposes. Three different techniques were used for classification and identification - relative polymer content (RPC), target compound identification (TCI), and linear discriminant analysis (LDA). LDA was found to be the most successful technique, correctly classifying 31 of 36 tyre residues. PyGCMS allows for simple analysis of tyre samples and residues without pre-treatment. A tyre sample was found to have 5-10% variation in the relative polymer content, regardless of when during the life of the tyre the sample was taken. Variation was found between tyres from the same manufacturer. Both similarities and differences were found between tyres from the same production batch and different production batches, suggesting that homogeneity in a single production batch not guaranteed and that manufacturers will also change the composition of a tyre between different production batches. The collection of tyre residues (like the collection of any forensic evidence) may or may not be successful depending specifically on the type of road surface. Collection of tyre residues from a concrete road with gravel aggregate was successfully achieved through picking. Collection of tyre residues from a bitumen road was successfully achieved; however adhesive contamination from both the fingerprint lift and clear adhesive tape interfered with the PyGCMS analysis. Tyre residues were successfully correlated to the source tyre, but the process of collecting sample information from numerous replicate analyses of both the tyre sample and residue for data analysis was a time-consuming one

Thermally stable laminating resins Final report

Polyimide resin and resin reinforced composite

Effect of fuel nitrogen and hydrogen content on emissions in hydrocarbon combustion

How the emissions of nitrogen oxides and carbon monoxide are affected by: (1) the decreased hydrogen content and (2) the increased organic nitrogen content of coal derived fuels is investigated. Previous CRT experimental work in a two stage flame tube has shown the effectiveness of rich lean two stage combustion in reducing fuel nitrogen conversion to nitrogen oxides. Previous theoretical work gave preliminary indications that emissions trends from the flame tube experiment could be predicted by a two stage, well stirred reactor combustor model using a detailed chemical mechanism for propane oxidation and nitrogen oxide formation. Additional computations are reported and comparisons with experimental results for two additional fuels and a wide range of operating conditions are given. Fuels used in the modeling are pure propane, a propane toluene mixture and pure toluene. These give hydrogen contents 18, 11 and 9 percent by weight, respectively. Fuel bound nitrogen contents of 0.5 and 1.0 percent were used. Results are presented for oxides of nitrogen and also carbon monoxide concentrations as a function of primary equivalence ratio, hydrogen content and fuel bound nitrogen content