Most electrolytic capacitors are polarized and require one of the electrodes to be positive
relative to the other; they may catastrophically fail if voltage is reversed.
This is because a reverse-bias voltage above 1 to 1.5 V will destroy the center layer of
dielectric material via electrochemical reduction (see redox reactions).
Following the loss of the dielectric material, the capacitor will short circuit,
and with sufficient short circuit current, the electrolyte will rapidly heat up and either
leak or cause the capacitor to burst, often in a spectacularly dramatic fashion.
More............
Electrolytic capacitor - Wikipedia, the free encyclopedia
After this redox reaction capacitor act more resistive ie. capacitor parallel resistance
increases and capacitance value decreases.
In this FF-circuit Rb=100k . When capacitance parallel resistance is eg. 10kohms,
transistors bias points are not correct and circuit can not oscillate.
KAK