Thermal behaviour of rigid polyurethane foams

Gjurova, K.; Troev, K.; Bechev, Chr; Borisov, G.

doi:10.1007/bf01914552

Cited by 6 publications

(3 citation statements)

References 6 publications

(7 reference statements)

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“…The variation of activation energy demonstrated the complexity of the process—at the early stage urethane bond dissociation dominates, then the polyol component may contribute to a weight loss at higher conversions, causing an increase of E a by 15 kJ/mol. The effects of different phosphonates and phosphates on the mechanism and kinetics of the decomposition reactions of rigid PUR foams, based on a polyol component obtained from by‐products of the synthesis of dimethyl terephthalate and polymeric MDI, have been studied by Gjurova et al11 It was found that at the initial stage of decomposition the presence of additive in low concentrations does not affect E a substantially, while for the second stage it increases by ca. 30 kJ/mol.…”

Section: Resultsmentioning

confidence: 99%

Thermal degradation studies on rigid polyurethane foams blown with pentane

Pielichowski¹,

Kulesza²,

Pearce

2003

J of Applied Polymer Sci

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ABSTRACT:The effect of sodium dihydrogenphosphate, trisodium pyrophosphate, and sodium aluminocarbonate on the thermal decomposition of rigid polyurethane (PUR) foams, based on diphenylmethane-4,4-diisocyanate, diphenyl-2,2-propane-4,4-dioxyoligo(ethylene oxide), and oxyalkylenated toluene-2,6-diamine, blown with pentane, was studied. Thermogravimetric (TG) data have shown that there is a stabilization effect of additives in the initial stage of degradation, both in nitrogen and air atmosphere, and the decomposition proceeded in two steps up to 600°C. Results of the kinetic analysis by the isoconversional methods of Ozawa-Flynn-Wall and Friedman yielded values of (apparent) activation energy (E a ) and preexponential factor (A). For phosphate-stabilized PUR samples, E a remained stable over a broad area of the degree of conversion, while for carbonate-containing sample two regions of E a were observed. Further advanced kinetic analysis by a nonlinear regression method revealed the form of kinetic function that was the best approximation for experimental data-for a two-stage consecutive reaction the first step was the Avrami-Erofeev nucleation-dependent model, and the second step was a chemical reaction (1st or nth order) model. The integrated thermogravimetric (TG)/Fourier transform infrared (FTIR) technique probed the thermal degradation of modified PURs by analyzing the evolved gases. The solid residue remaining at different temperatures was identified by diffuse reflection FTIR (Kubelka-Munk format). The complex thermal behavior was discussed on the basis of the obtained results-it can be shown that the global stabilization effect is a multistage process whose initial conditions are of critical importance in governing the nature of the entire process.

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Section: Resultsmentioning

confidence: 99%

Thermal degradation studies on rigid polyurethane foams blown with pentane

Pielichowski¹,

Kulesza²,

Pearce

2003

J of Applied Polymer Sci

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“…In the thermal degradation studies of rigid PUR foams by many investigators,28–30 Pielichowski et al29, 30 have shown that there is a stabilization effect of additives such as sodium dihydrogenphosphate, trisodium pyrophosphate and sodium aluminocarbonate in the initial stage of degradation, and the decomposition proceeded in two steps up to 600°C. Figure 8 shows thermogravimetric analysis of the PIR‐PUR foams which contains tris(chloro 2‐propyl) phosphate.…”

Section: Resultsmentioning

confidence: 99%

Effects of liquid‐type silane additives and organoclay on the morphology and thermal conductivity of rigid polyisocyanurate‐polyurethane foams

Kim

Kang

Park

et al. 2011

J of Applied Polymer Sci

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This article investigates the effects of liquid-type silane additives and organoclay as a solid-type additive on the morphological, mechanical and thermal insulating properties of polyisocyanurate-polyurethane (PIR-PUR) foams. The organoclay likely acted as nucleating agents during the formation of PIR-PUR foams. When the liquid silane additives and organoclay were added, the cell size and thermal conductivity of the PIR-PUR foams appeared to be decreased. However, organoclay did not contribute to reduce the cell size distribution of the foam. PIR-PUR foams synthesized with tetramethylsilane as a liquid-type additive showed a smaller average cell size and lower thermal conductivity than that of PIR-PUR foams synthesized with the other silane additives or with organoclay as a solid-type additive. For the PIR-PUR foam with organoclay/TEMS (1.5/1.5 php) mixture, cell size and thermal conductivity of the foam showed similar to the foam with TEMS. These results suggest that smaller cell size appears to be one of the major factors in the improvement of thermal insulation properties of the PIR-PUR foams. Silane additives did not seem to have a strong effect on the flammability of the PIR-PUR foams. However, heat resistance was more dominant for the foam with the organoclay at the higher temperature.

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“…In most of the compositions CR'700 has a larger percentage than that of the IC, this tendency being expressed at its best for compositions 1. (Table 1) influences more considerably the temperature of the first exothermic effect (T1), which is in connection with the flammability tendency of polymers [9][10][11][12][13][14][15]. For most of the studied PChC, T1 shifts towards higher temperatures, especially for compositions 1 and 2 which have a higher AS content, while for compositions 3 7"1 does not change its position on the temperature scale.…”

Section: Thermal Characteristicsmentioning

confidence: 87%

Investigations of thermal behaviour and flammability of antipyrene-containing polychloroprene compositions

Gjurova

Karaivanova

1991

Journal of Thermal Analysis

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The effects of ammonium salt of sulphaminic acid (AS), introduced as antipyrene in polyehloroprene compositions based on 'Byprene-210' in combination with antimony trioxide (AO) and chloroparaffin (ClaP) are studied by means of a combined dynamic thermal analysis. After successive examination of the obtained thermal and flammability characteristics, it is assumed that AS and AO exhibit additive influence. The optimal range of coneentrations of AS for which it is possible to substitute AO in the investigated polyehloroprene compositions is established.It is known that filled vulcanizates of chloroprene rubber belong to the group of the self-extinguishing compositions. Nevertheless, they should meet a number of additional requirements concerning smoke release, etc.For reducing the flammability of chlorine-containing polymers releasing hydrogen chloride on heating, antimony trioxide (AO) is used as an antipyrene, because the hydrogen chloride/AO system exhibits a synergetic fire-retardation effect [1,2].The use of AO, however, has some disadvantages, such as raising the cost of the compositions, making worse the operational and ecological characteristics. These reasons necessitate the creation of fire-protected polychloroprene compositions (PChC) containing organic antipyrenes, which do not aggravate the operational characteristics and are easy to process and ecologically safe. Such a combination of properties can be found in some nitrogen-sulphur-containing organic compounds [3], having low toxicity both in the process of formation and in the process of exploitation of the polymer compositions. In one of our previous papers [4] we offered investigations on the influence of ammonium salt of sulphaminic acid (AS), obtained by us [5] in combination with AO and chloroparaffin, on the physicomechanical characteristics of PChC on the base of 'Byprene-2IO' produced for conveying belts. It was shown that in concentrations from 3 to 12 wt.% AS does not change the basic strength characteristics of PChC beyond the practical standard, it is easy to dose and ensures good processability. AS was found to possess antipyrene qualities for the investigated compositions. The results obtained did not, however, make clear the mechanism of influence of AS on the processes taking place in the system on heating, i.e. what is the cause for its fire-retarding effect.Valuable information on the total mechanisms of operation of antipyrenes can be obtained by studying the thermal behaviour of the polymer systems in a broad temperature interval. Such investigations are based on the correlations found between some characteristics of flammability, on one hand, and of thermal destruction of polymers, on the other, and they are of great help for marking the effect of the antipyrenes [6,7].The aim of the present work is to study the influence of organic ammonium salt of sulphaminic acid (AS) in combination with AO and chloroparaffin (ChP) on the thermal behaviour and flammability of PChC, produced for conveying belts. ExperimentalThe organic antipyr...

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Thermal behaviour of rigid polyurethane foams

Cited by 6 publications

References 6 publications

Thermal degradation studies on rigid polyurethane foams blown with pentane

Thermal degradation studies on rigid polyurethane foams blown with pentane

Effects of liquid‐type silane additives and organoclay on the morphology and thermal conductivity of rigid polyisocyanurate‐polyurethane foams

Investigations of thermal behaviour and flammability of antipyrene-containing polychloroprene compositions

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