engleski

Different treatments of radiation-cured polymers and their influence on the long-time behaviour

The mechanical and photoelastic properties of polymers are influenced by the storage temperature and storage time before using them as model materials in photoelastic experiments. As an example, Fig. 1 shows for a material D (internal notation of ARCS), produced with a relatively low radiation dose of 20 kGy, the stressoptical coefficients as a function of time, fs(t), deu to the optical creep for test specimens after a storage time of 1, 3 and 7 days, stored at 10 °C (group A) and of 3 and 7 days, stored at 23 °C (group B). A comparison of these two groups shows in this case a big influence of the storage temperature. For T=10 °C (or even below) the influence of the storage time is very small, however there is already a remarkable influence of the storage time if the specimens are stored at 23 °C (or even above). Fig. 2 demonstrates these results showing the value fs(~ 3 h) at the practical end of the creep phase. The calibration measurements were carried out using diametrically loaded circular discs. The creep behaviour shown in Fig. 1 can be improved using a higher initial radiation dose Di. However Di influences also the ability to fix the fringe pattern by the radiation treatment of a deformed photoelastic model. That means from the viewpoint of the goal of these investigations that we have to deal with an optimization procedure which is of course different for different problems.

polymer; radiation; photoelasticity; optical creep; storage temperature; storage time

nije evidentirano