This part of IEC TS 61244, which is a technical specification, reviews experimental techniques to quantitatively monitor the effects when oxygen is present during ageing of polymers in various environments including temperature, radiation or ultraviolet.<\/p>\n
Inhomogenous ageing effects caused by diffusion-limited oxidation are often encountered and provide theoretical equations to estimate their importance. These effects make it difficult to understand the ageing process and to extrapolate accelerated exposure to long-term conditions.<\/p>\n
It is widely known that mechanical properties degrade prior to electrical properties.These changes are consequences of chemical changes such as oxidation. In this technical specification, only mechanical or chemical monitoring techniques are of interest.<\/p>\n
This technical specification does not deal with electrical monitoring techniques.<\/p>\n
| PDF Pages<\/th>\n | PDF Title<\/th>\n<\/tr>\n | ||||||
|---|---|---|---|---|---|---|---|
| 4<\/td>\n | English \n CONTENTS <\/td>\n<\/tr>\n | ||||||
| 6<\/td>\n | FOREWORD <\/td>\n<\/tr>\n | ||||||
| 8<\/td>\n | INTRODUCTION <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | 1 Scope 2 Profiling techniques to monitor diffusion-limited oxidation 2.1 General 2.2 Infra-red profiling techniques <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | Figures \n Figure 1 \u2013 Relative oxidation as determined from the carbonyl absorbance versus depth away from air-exposed surface of polyolefin material after ageing for 6 days at 100 \u00b0C (from [18]) <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | Figure 2 \u2013 Depth distribution of carbonyl groups in irradiated (0,69 Gy\/s) multilayer \nsamples composed of 4, 18, 27 and 44 films of 22 \u00b5m thickness <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 2.3 Modulus profiling Figure 3 \u2013 Micro-FTIR spectrophotometric determination of photoproduct and of residual double-bond profiles in a SBR film photooxidized for 100 h <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | Figure 4 \u2013 Schematic diagram of modulus profiling apparatus <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | Figure 5 \u2013 Modulus profiles of 1,68 mm thick commercial fluoro elastomer samples after air ageing at 5,49\u00a0kGy\/h and 70 \u00b0C to the indicated radiation doses (from [15]) Figure 6 \u2013 Modulus profiles of 1,68 mm thick commercial fluoro elastomer samples after air ageing at 0,90\u00a0kGy\/h and 70\u00a0\u00b0C to the indicated radiation doses (from [15]) <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | Figure 7 \u2013 Modulus profiles of 1,68 mm thick commercial fluoro elastomer samples after air ageing at 0,14\u00a0kGy\/h and 70 \u00b0C to the indicated radiation doses (from [15]) Figure 8 \u2013 Modulus profiles of 1,9 mm thick chloroprene rubber samples followingelevated temperature exposures in the presence of air at 150 \u00b0C,left plot, and 100 \u00b0C, right plot (from [10]) <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | 2.4 Density profiling Figure 9 \u2013 Experimental density profiles (crosses) for 0,302 cm (left) and 0,18 cm (right)thick EPDM sheets after ageing at 6,65 kGy\/h and 70 \u00b0C in airX-ray microanalysis <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | Figure 10 \u2013 Effect of total radiation dose on XMA profile for 2 mm thickEPDM sheet irradiated at 1 kGy\/h in air (from [24]) <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | 2.5 Miscellaneous profiling techniques Figure 11 \u2013 XMA profiles of 1\u00a0mm thick EPDM sheets after thermal ageing in air (from [24]) <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | Figure 12 \u2013 NMR self-diffusion coefficients versus distance away from samplesurface for low-density polyethylene samples after gamma-irradiationin air or vacuum at 0,6 Gy\/sec for the indicated total doses (from [26]) Figure 13 \u2013 Chemiluminescence profile for a polypropylene material aftergamma irradiation in air to 0,05 MGy at 2 kGy\/h (data from [30]) <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | 3 Theoretical treatments of diffusion-limited oxidation <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | Figure 14 \u2013 Theoretical oxidation profiles for various values of \u03b1 (indicated in the figure) with \u03b2 \n = 0,1 <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | Figure 15 \u2013 Identical to Figure 14, except that \u03b2 \n = 10 Figure 16 \u2013 Identical to Figure 14, except that \u03b2 \n = 1 000 <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | 4 Permeation measurements 5 Oxygen consumption measurements Figure 17 \u2013 Plot of \u03b1c\/(\u03b2 + 1) versus \u03b2 \n, where \u03b1c denotes the value ofintegrated oxidation corresponding to 90 % (from [7, 23]) <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | 6 Comparison of theory with experimental results <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | 7 Oxygen overpressure technique <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | Figure 18 \u2013 Apparatus used for irradiation under pressurized oxygen conditions <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | 8 Summary Figure 19 \u2013 Tensile elongation (left) and tensile strength (right) data for an EPRmaterial aged at the indicated high and low dose-rates in air andat high dose rate in the pressurized oxygen apparatus of Figure 18 <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | Annex A (informative) Derivation of theoretical treatment of diffusion-limited oxidation A.1 General Figure A.1 \u2013 Simplified kinetic scheme used to represent the oxidation of polymers(from [44, 45]) <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | A.2 Numerical simulation <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | A.3 Cylindrical and spherical geometries and simulation <\/td>\n<\/tr>\n | ||||||
| 33<\/td>\n | Figure A.2 \u2013 Typical example of normalized concentration of oxygen for cylindrical shape for \u03b2 \n=0,01 from [46] Figure A.3 \u2013 Typical example of relative oxygen consumption for cylindrical shape for \u03b2 \n=0,01 from [46] <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | Figure A.4 \u2013 Typical example of normalized concentration of oxygen for cylindrical shape for \u03b2 \n=100 from [46] Figure A.5 \u2013 Typical example of relative oxygen consumption for cylindrical shape for \u03b2 \n=100 [46] <\/td>\n<\/tr>\n | ||||||
| 35<\/td>\n | Figure A.6 \u2013 Typical example of normalized concentration of oxygen for spherical shape for \u03b2 \n=0,01 from [46] Figure A.7 \u2013 Typical example of relative oxygen consumption for spherical shape for \u03b2 \n=0,01 from [46] <\/td>\n<\/tr>\n | ||||||
| 36<\/td>\n | Figure A.8 \u2013 Typical example of normalized concentration of oxygen for spherical shape for \u03b2 \n=100 from [46] Figure A.9 \u2013 Typical example of relative oxygen consumption for spherical shape for \u03b2 \n=100 [46] <\/td>\n<\/tr>\n | ||||||
| 37<\/td>\n | A.4 Time dependence of the simulation Figure A.10 \u2013 Typical example of time-dependent normalized concentration of oxygen at the centre from for the case of \u03b2 \n=1 [46] <\/td>\n<\/tr>\n | ||||||
| 38<\/td>\n | Figure A.11 \u2013 Typical example of time-dependent normalized concentration of oxygen at the centre from for the case of \u03b1 \n=50 [46] <\/td>\n<\/tr>\n | ||||||
| 39<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Determination of long-term radiation ageing in polymers – Techniques for monitoring diffusion-limited oxidation<\/b><\/p>\n |