AGEING STRENGTH OF HARD PVC

ALTERUNGSBESTAENDIGKEIT VON HART-PVC

THE WORK IS A CONTINUATION OF EARLIER STUDIES OF CHEMICAL METHODS FOR DETERMINING THE RESISTANCE TO AGEING OF RIGID PVC. IN THIS WORK THE MECHANICAL BEHAVIOUR OF THE MATERIAL IS STUDIED. IT WAS FOUND THAT THE TENSILE TEST IS UNSUITABLE FOR DETERMINING THE RESISTANCE TO AGEING. THE IMPACT BEND TEST RELATES MORE TO THE STRESSES NORMALLY ENCOUNTERED IN PRACTICE. IT MUST BE CARRIED OUT AT LOW SAMPLE TEMPERATURES. SAMPLES ABOUT 3 MM THICK OR MORE HAVE A PUNCHED HOLE OF 3 MM DIAMETER. THE WEATHERED SIDE OF THE SAMPLE MUST LIE IN THE TENSION ZONE OF THE SAMPLE. AN ACCELERATED WEATHERING OF 1000 HOURS IN THE "XENOTEST APPARATUS" CORRESPONDS TO AN OUTDOOR WEATHERING IN CENTRAL EUROPE OF LESS THAN 12 MONTHS. INITIAL DAMAGE CAN BE RECOGNIZED AFTER 18-24 MONTHS OF OUTDOOR WEATHERING.