Autocatalysis in thermal decomposition of polymers

Bianchi

Polymer Engineering & Sci

et al. 2019

Fluoroelastomer (FE) reinforced with carbon nanofiber (CNF) (1 and 2 phr) was prepared using an instrumented batch mixer. A property–structure relationship was compared with the compounds containing carbon black (30 phr), neat FE, and hybrid sample (nanofiber + carbon black, 2 phr + 30 phr, respectively). Nanofiber did not improve the mechanical behavior while swelling characteristic was improved as well the initial weight loss by thermogravimetry. The compounds achieve conductive characteristic using only 1 phr. The thermal decomposition of the compounds was carried out using different kinetic approaches in order to establish consistent parameters. It has been shown that the approaches using consistent kinetic parameters can be combined in such a way as to enhance the reliability and quality of each other and consequently the overall kinetic analysis. The limited dispersion with agglomerations seems to be the crucial factor for all analyses evaluated. Finally, the synergism between nanofiber and carbon black for hybrid compound make CNFs very attractive to be used as an additive in the elastomeric composition. POLYM. ENG. SCI., 59:1223–1232 2019. © 2019 Society of Plastics Engineers

Section: Resultsmentioning

confidence: 72%

Fluoroelastomers reinforced with carbon nanofibers: A survey on rheological, swelling, mechanical, morphological, and prediction of the thermal degradation kinetic behavior

Bianchi

Polymer Engineering & Sci

et al. 2019

“…It can be noticed that calculations using pyrolysis kinetics derived from the counterflow flame conditions provide a reasonable agreement with the experimental data on the mass burning rate. As for the kinetic parameters obtained by microscale combustion calorimetry, the mass burning rate was found to be substantially underestimated, because such a content is hardly applicable to the polymer's sample mass of approximately 3 mg. Moreover, the heating rate of around 1 K/s carried out here stands rather far from that realized in counterflow combustion.…”

Section: Resultsmentioning

confidence: 99%

“…Table presents two sets of kinetic parameters of pyrolysis reaction considered here, which were derived from the measurements in counterflow flame and by microscale combustion calorimetry …”

Section: Input Datamentioning

confidence: 99%

“…20,21 3 | INPUT DATA Table 1 presents two sets of kinetic parameters of pyrolysis reaction considered here, which were derived from the measurements in counterflow flame 22 and by microscale combustion calorimetry. 23 Another point is to be taken into account to finalize the physical content of the presented mathematical model. As found in the experimental study, 10 the process of thermal degradation of ultrahigh molecular-weight polyethylene results in formation of a melted layer on the burning surface.…”

Section: Formulationmentioning

confidence: 99%

See 1 more Smart Citation

Numerical study of polyethylene burning in counterflow: Effect of pyrolysis kinetics and composition of pyrolysis products

et al. 2018

Summary The burning behavior of polyethylene in the counterflow of oxidizing air has been studied numerically with a coupled model describing feedback heat and mass transfer between gas‐phase flame and polymeric solid fuel. A 2‐dimensional elliptic equation in axisymmetric formulation (revealing the cylindrical shape of the polymer sample used in the experiment) has been employed to simulate heat transfer in solid fuel, and a set of 1‐dimensional hyperbolic equations has been used to determine the solid‐to‐gas conversion degree of the pyrolysis reaction. Four sets of products compositions and two modifications for the kinetic parameters of solid fuel pyrolysis reaction have been taken into account. Gas‐phase formulation is presented by set of 1‐dimensional conservation equations for multi‐component flow with detailed kinetic mechanism of combustion. The profiles of temperature and species concentrations in the flame zone have been calculated and compared with the results of experimental study of combustion of ultrahigh molecular weight polyethylene. Higher hydrocarbon composition (dodecane) has been found to show the best agreement between the temperature and species concentration profiles with the measurements, especially for the low‐level mass fractions of the by‐product components—propylene, butadiene, and benzene.

“…According to the identified decomposition products of phenol and iso-propylphenol, the decomposition mechanism of the BERs is investigated. Some previous works [26][27][28][29] have proved that the decomposition of polymer belongs to a free radical reaction at high temperatures. On the basis of bond-energy theory, it needs much more energy to break down the bonds of polymer so as to produce free radicals.…”

Section: Mechanism Of Decomposition Reaction Of Bersmentioning

confidence: 99%

Separation and Recovery of Copper Foil and Fabric from Waste Printed Circuit Boards by Decomposing Brominated Epoxy Resin Using Near Critical Water

Kang¹,

Shao²,

Guo³

et al. 2018

Eng. Sci.

Waste printed circuit board (WPCB), a heterogeneous mixture of brominated epoxy resins (BERs), glass fibers and metals, has the challenge to separate and recover valuable materials. In this paper, an effective and benign near critical water (NCW) method was applied to decompose BERs to recover the glass fabric and metals. The effects of parameters including temperature, reaction time, feed ratio, acid-base catalyst, and size of WPCBs on the decomposition ratio of BERs were investigated. The results showed that the decomposition ratio of BERs reached a maximum value of 98.7% under the optimum conditions at 320°C, reaction time of 150 min, feed ratio of 5 mL/g, HCl catalyst, and the size of 5×5 mm 2. The gas chromatography-mass spectrometry (GC/MS) result showed that the main components of liquid decomposition product were phenol (69.8%) and its derivatives (17.8%). A probable mechanism of the decomposition reaction of BERs was proposed. After NCW treatment, the glass fabric and copper foils in the residue were easily recovered by a simple artificial screening separation. The surface of recovered fabric was very clean and no damages were observed. Meanwhile, the purity of copper foil reached 97.86%. This study provides a green technology to recover valuable materials from WPCBs.