The investigation of thermal decomposition pathway and products of poly(vinyl alcohol) by TG‐FTIR

Abstract

A generalized form of a semiquantitative method has been developed based on the multilinear least-squares regression technique applied on the entire FTIR absorbance spectrum of a gaseous mixture to determine components concentration. Thermal degradation of poly(vinyl alcohol) samples with high, PVA(98), and low degree of hydrolysis, PVA(80), has been investigated by TG-FTIR simultaneous analysis performed in an inert atmosphere. Analysis of gaseous products was carried out using a routine developed in Matlab and this routine returns the product concentration with a reasonable RMS error. The correlation coefficients of the original mixture spectrum with the mixed output were obtained at some specific peak temperatures using irAnalysis software. The first process is the loss of physically adsorbed water which followed by two main processes of thermal degradation. In spite of the similarity of evolved gaseous products, two samples showed some differences in components concentrations identified in the volatile mixture. Acetaldehyde has been identified as the main volatile product in the first thermal degradation step of PVA(98) and PVA(80). The second major degradation product of PVA(80) is acetic acid due to presence of more residual acetate group while 2-butenal have been identified for PVA(98). Water was mainly produced in the first stage of thermal degradation of PVA(98) while it was identified in the first and second stages for PVA(80). This might be attributed to existence of a competition between water and residual acetate group for elimination that postpones the complete elimination of OH group to the second degradation stage.

Identification of gas-phase pyrolysis products in a prescribed fire: first detections using infrared spectroscopy for naphthalene, methyl nitrite, allene, acrolein and acetaldehyde

“…The major gas-phase compounds emitted from wildland fires are H 2 O, CO 2 , CO and CH 4 (Ward and Hardy, 1991), all of which are easily identified and quantified via FTIR spectroscopy. Lightweight hydrocarbons, oxygenated hydrocarbons, nitrogen and sulfur species are all minor products generated during burns (Yokelson et al, 1996;Lobert et al, 1991;Talbot et al, 1988). A host of more complex gases that can condense to form tar are also produced by pyrolysis of wildland fuels (Amini et al, 2019;Safdari et al, 2018).…”

Role of caged bicyclic pentaerythritol phosphate alcohol in flame retardancy of PA6 and mechanism study

“…With the increase of temperature, the intensity of the peak of CO 2 appearing at about 30 min (640 °C), later than PA6, was obviously lower than that of PA6. CO 2 , CO, CH 4 , and other gas products resulted from the second degradation of the large molecules that decomposed first . The decrease of these peak intensities indicated that the flame retardant of the condensed phase began to play a flame‐retardant role at this temperature, which made the flame‐retardant carbon layer appear.…”

“…CO 2 , CO, CH 4 , and other gas products resulted from the second degradation of the large molecules that decomposed first. [32][33][34][35] The decrease of these peak intensities indicated that the flame retardant of the condensed phase began to play a flame-retardant role at this temperature, which made the flame-retardant carbon layer appear. The carbon layer prevented the further decomposition of the system, resulting in more stable aromatic carbon and esterification.…”

Kinetic Modeling of Photodegradation of Water-Soluble Polymers in Batch Photochemical Reactor

“…where s ¼ 1 f0r chain-end scission and 2 ≤ s ≤ r: Reactions (20)-(26) represent the complete mineralization of polymer compounds. It has been experimentally proven that the acidity of the treated solution varies during the degradation reaction by the UV/H 2 O 2 process [17,39]. The pH decreases at the beginning of the reaction, and the solution becomes more acidic due to the formation of intermediate oxidation products such as carboxylic acids [42].…”