This part of IEC TS 61244, which is a technical specification, applies to procedures for predicting ageing of polymeric materials at low dose rates.<\/p>\n
The object is to present three methods which can be used to extrapolate data obtained fromhigh dose rate experiments to the low dose rates typical of service conditions. These methods assume that homogeneous oxidation has been achieved under the test conditions. The techniques described in the following clauses are methods which have been found to be useful for a range of elastomeric, thermoplastic and thermoset materials. The procedures require a considerable number of test data to enable predictions to be made under low dose rate conditions.<\/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 | 1 Scope 2 Normative references 3 General <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | 4 Power law extrapolation method 4.1 Description 4.2 Test procedure 4.3 Determination of model parameters <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | 4.4 Limitations Figures \n Figure 1 \u2013 Interpolation of the end-point dose (schematic), showing a plot of relative elongation at break plotted vs dose with interpolation of DED values at 0,75 and 0,5 Figure 2 \u2013 Extrapolation of end-point dose to lower dose rates (schematic) showing the plot of DED values vs dose rate <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | 5 Superposition of time dependent data 5.1 Description 5.2 Test procedure Figure 3 \u2013 Limitations \u2013 Extrapolation of DED near thermal ageing limit (schematic) <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 5.3 Determination of model parameters Figure 4 \u2013 Determining shift factors a (T,0) for thermal ageing <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | Figure 5 \u2013 Superposition of data to yield master curve Figure 6 \u2013 Determination of activation energy E <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | Figure 7 \u2013 Determination of shift factors a (T, D \n) for combined thermal-radiation ageing, relative to the master curve in Figure 4 <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | 5.4 Limitations Figure 8 \u2013 Fitting experimental values of a (T, D \n) to the empirical model Equation (2) Figure 9 \u2013 Calculated DED using Equation (5) <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | 6 Superposition of DED data 6.1 Description 6.2 Test procedure 6.3 Evaluation <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | 6.4 Limitations Figure 10 \u2013 DED values under combined thermal-radiation conditions (schematic) Figure 11 \u2013 Superposition of DED data (schematic) <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | Annex A (informative) Behaviour of polymeric materials in radiation environments <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | Figure A.1 \u2013 Schematic illustrating the types of dose rate effects which can occur in radiation aged polymeric materials <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | Annex B (informative) Examples of use of the power law method B.1 General B.2 Polypropylene filaments B.3 Crosslinked polyethylene (XLPE) Figure B.1 \u2013 Elongation at break of polypropylene irradiated in air (from [10]) <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | Figure B.2 \u2013 Extrapolation of end-point dose from data in Figure B.1 Figure B.3 \u2013 Dose required to reach 100\u00a0% elongation at 20\u00a0\u00b0C for an XLPE cable insulation material [11] <\/td>\n<\/tr>\n | ||||||
| 23<\/td>\n | Annex C (informative) Use of the superposition principle Figure C.1 \u2013 Schematic \u2013 Superposition principle for thermal ageing <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | Figure C.2 \u2013 Schematic \u2013 Superposition principle for combined thermal-radiation ageing <\/td>\n<\/tr>\n | ||||||
| 25<\/td>\n | Annex D (informative) Examples of use of the superposition of time dependent data D.1 Ethylene propylene (EPDM) elastomer D.2 Nitrile elastomer D.3 Ethylene vinyl acetate (EVA) polymer <\/td>\n<\/tr>\n | ||||||
| 26<\/td>\n | Figure D.1 \u2013 Experimental data for EPDM elastomer fitted to the superposition model Figure D.2 \u2013 Calculated DED for 50 % compression set at 20\u00a0\u00b0C <\/td>\n<\/tr>\n | ||||||
| 27<\/td>\n | Figure D.3 \u2013 Calculated DED for 50 % compression set at 40\u00a0\u00b0C Figure D.4 \u2013 Calculated DED for e\/e0\u00a0= 0,5 <\/td>\n<\/tr>\n | ||||||
| 28<\/td>\n | Annex E (informative) Examples of use of the superposition of dose to equivalent damage (DED) data E.1 General E.2 Neoprene cable jacket E.3 Chlorosulphonated polyethylene (CSPE) cable jacket E.4 Crosslinked polyolefin (XLPO) cable insulation E.5 Poly vinyl chloride (PVC) cable jacket <\/td>\n<\/tr>\n | ||||||
| 29<\/td>\n | Figure E.1 \u2013 Superposition of DED data at 50\u00a0\u00b0C for a neoprene cable jacket material [7] <\/td>\n<\/tr>\n | ||||||
| 30<\/td>\n | Figure E.2 \u2013 Superposition of DED data for several different CSPE cable jacket materials <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | Figure E.3 \u2013 Superposition of DED data for a XLPO cable insulation material [7] Figure E.4 \u2013 Superposition of DED data for PVC showing complex dose rate dependence \u2013 Homogeneous oxidation data only <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | Bibliography <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Determination of long-term radiation ageing in polymers – Procedures for predicting ageing at low dose rates<\/b><\/p>\n |