On the thermal stability of some macromolecular compounds

Ciutacu, S.; Fãtu, D.; Segal, E.

doi:10.1016/0040-6031(88)80081-9

Cited by 11 publications

(5 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As shown in our previous review articles [29,30], the validity of relationship (5) shows that the change of an operational parameter as the heating rate or the atmosphere in which the degradation occurs determines the change of the non-isothermal kinetic parameters. The parallelism of the straight lines in Fig.…”

Section: Methodsmentioning

confidence: 87%

“…The parameters of these straight lines and corresponding the values of the non-isothermal kinetic parameters of the degradation depend on theheating rate as well as of the atmosphere in which the thermal degradation is recorded, As shown in Fig. Figure 6 shows that the kinetic parameters of the degradation in oxygen flow are also correlated through relationship (5). Figure 6 shows that the kinetic parameters of the degradation in oxygen flow are also correlated through relationship (5).…”

Section: Methodsmentioning

confidence: 88%

“…Figures 3-5 show the straight lines [ln(13(dAm/dT))+lnAm] vs.(1/T), for various heating rates in the three media in which the derivatograms have been recorded. 6 the non-isothermal kinetic parameters of the degradation in static air atmosphere and in air flow together with the corresponding isothermal kinetic parameters are correlated through the compensation effect [29,30] characterized by the relationship: lnA(Ammax) 2 = aE + b (5) where a and b are constants specific for the given series of related reactions. 6 the non-isothermal kinetic parameters of the degradation in static air atmosphere and in air flow together with the corresponding isothermal kinetic parameters are correlated through the compensation effect [29,30] characterized by the relationship: lnA(Ammax) 2 = aE + b (5) where a and b are constants specific for the given series of related reactions.…”

Section: Methodsmentioning

confidence: 99%

“…Thermal analysis methods (TG, DTG, DTA or DSC) are very useful in the solution of such problems as they permit the estimation of the temperature range of thermal stability [1][2][3][4][5][6], the values of the non-isothermal kinetic parameters of degradation [6][7][8][9][10][11][12][13][14][15][16][17][18] and the changes undergone as a consequence of the accelerated aging [2, 19, 201. In our previous papers [21][22][23] we have shown that the increase of oxygen pressure determines the acceleration of the isothermal thermomechanical degradation of ethylene+propylene rubber (elongation at break), glass-reinforced epoxy resin (flexural strength), and nitrile-butadiene rubber (elongation at break).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Thermooxidative degradation of an unsaturated polyester resin

Budrugeac¹,

Segal

1997

Journal of Thermal Analysis

Self Cite

View full text Add to dashboard Cite

The results of non-isothermal kinetic analysis of the thermooxidative degradation in air and oxygen of an unsaturated polyester resin are presented. It has been shown that the thermooxidative degradation in oxygen occurs at lower temperatures than the thermooxidative degradation in air. The kinetic parameters of the thermooxidative degradation depend on the heating rate and the oxygen pressure. Two straight lines of lnA vs. E (,4 is the preexponential factor and E is the activation energy), characteristic for the compensation effect, have been obtained for the thermooxidative degradation in air and in oxygen respectively. The difference between the intercepts of these straight lines can be explained by dependence of the pre-exponential factor on the oxygen pressure.

show abstract

Section: Methodsmentioning

confidence: 87%

Section: Methodsmentioning

confidence: 88%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Thermooxidative degradation of an unsaturated polyester resin

Budrugeac¹,

Segal

1997

Journal of Thermal Analysis

Self Cite

View full text Add to dashboard Cite

show abstract

“…For thermal degradation, the acceleration factor has to be chosen so that the mechanism of accelerated degradation of the material should be identical with that of the degradation under practical conditions. To solve such a problem, thermal analysis methods (TG, DTG and DTA) are very useful as they allow determination of the temperature range of thermal stability [2][3][4][5][6][7], the nonisothermal kinetic parameters of the degradation [8][9][10] and the changes undergone by the investigated polymeric materials as a consequence of accelerated ageing [3, 11,12]. The nonisothermal kinetic parameters are very useful for determination of the thermal lifetime of polymeric materials [13,14].…”

mentioning

confidence: 99%

Thermooxidative degradation of nitrile-butadiene rubber

Budrugeac

Segal

Ciutacu

1991

Journal of Thermal Analysis

Self Cite

View full text Add to dashboard Cite

Results are presented on: (a) the nonisothermal degradation of nitrile-butadiene rubber (NBR) from TG, DTG and DTA data; (b) the accelerated isothermal thermal degradation of NBR at 80 ~ 90 ~ and 105 ~ from the change in weight versus time data; (c) the accelerated isothermal thermal degradation of NBR at 80 ~ 90 ~ and 105 ~ from the change in relative elongation at break with time.The thermal analysis data showed that the following processes occur successively during the nonisothermal heating of NBR in air: (1) the volatilization of the plasticizer and other ingredients; (2) the exothermie absorption of oxygen to yield nonvolatile oxidation products; (3) the decomposition of these products or their further interaction with oxygen to form volatile products.The results obtained from the three kinds of measurements were correlated to give a realistic picture of the processes responsible for the changes in the mechanical properties of the material as a consequence of its heating.The practical use of polymeric materials requires a knowledge of their behaviour under given environmental conditions (heat, light, nuclear radiation, humidity, etc.). In order to acquire such knowledge, one has to investigate the aeceleretated ageing of these materials by following the changes in their mechanical properties (elongation at break, resistance to traction, resistance to compression, etc.) and their electrical properties (dielectric rigidity, dielectric losses, etc.) due to thermooxidative degradation. The results of accelerated ageing permit an evaluation of the lifetime of the material under the conditions of practical use [1]. For thermal degradation,

show abstract

Thermal decomposition of aliphatic nylons

Levchik¹,

Weil²,

Lewin³

1999

Polym. Int.

367

254

View full text Add to dashboard Cite

An overview of the literature together with selected authors' data on thermal and thermo‐oxidative decomposition of commercial aliphatic nylons (nylon 6, nylon 7, nylon 11, nylon 12, nylon 6.6, nylon 6.10, nylon 6.12) is presented. Despite the high level of research activity and the large number of publications in the field, there is no generally accepted mechanism for the thermal decomposition of aliphatic nylons. Polylactams (nylon 6, nylon 11 and nylon 12) tend to re‐equilibrate to monomeric or oligomeric cyclic products. Diacid–diamine type nylons (nylon 6.6, nylon 6.10 and nylon 6.12) produce mostly linear or cyclic oligomeric fragments and monomeric units. Because of the tendency of adipic acid to fragment with elimination of CO and H2O and to undergo cyclization, significant amounts of secondary products from nylon 6.6 are reported in some papers. Many authors have shown that the primary polyamide chain scission occurs either at the peptide C(O)NH or at adjacent bonds, most probably at the alkyl–amide NHCH2 bond which is relatively the weakest in the aliphatic chain. Hydrolysis, homolytic scission, intramolecular CH transfer and cis‐elimination (a particular case of CH transfer) are all suggested as possible primary chain‐scission mechanisms. There are no convincing results reported which tend to generally support one of these mechanisms relative to the others; rather, it seems that the contribution of each mechanism depends on experimental conditions. This conclusion is also supported by the wide spread of kinetic parameters measured under the different experimental conditions. More uniform results are observed in the literature regarding the mechanism of thermo‐oxidative decomposition of aliphatic nylons. Most authors agree that oxygen first attacks the N‐vicinal methylene group, which is followed by the scission of alkyl–amide NC or vicinal CC bond. Alternatively, it is suggested that any methylene group which is β‐positioned to the amide group methylene can be initially oxidized. There are few mechanisms in the literature which explain discoloration (yellowing) of nylons. UV/visible active chromophores are attributed either to pyrrole type structures, to conjugated acylamides or to conjugated azomethines. Some secondary reactions occurring during the thermal or thermo‐oxidative decomposition lead to crosslinking of nylons. Nylon 6.6 crosslinks relatively easily, especially in the presence of air, whereas nylon 11 and nylon 12 crosslink very little. Strong mineral acids, strong bases, and some oxides or salts of transition metals catalyse the thermal decomposition of nylons, but minimize crosslinking. In contrast, many fire retardant additives promote secondary reactions, crosslinking and charring of aliphatic nylons. © 1999 Society of Chemical Industry

show abstract

On the thermal stability of some macromolecular compounds

Cited by 11 publications

References 4 publications

Thermooxidative degradation of an unsaturated polyester resin

Thermooxidative degradation of an unsaturated polyester resin

Thermooxidative degradation of nitrile-butadiene rubber

Thermal decomposition of aliphatic nylons

Contact Info

Product

Resources

About