Upvote:-1
The voucher typically comes with terms and conditions. These will spell out the specific rules: how long, what for, how to use it, etc. Without reading the rules it's hard to tell but most likely the answer is "no".
Air Canada flight to Dominican Republic from Newark airport was cancel and was offered a Travel voucher.
You should NOT have accepted the voucher but insisted on a full refund. In most cases airlines are required to give you full refund. In most cases the airlines will offer travel credit or a voucher instead. That's bad for you but good for the airline, so you should NOT accept it.
Once you accept the voucher, it's difficult to get your money back.