What is the advantage of using recycled PET fabric vs. cotton canvas?

Recycled PET fabric is essentially a form of polyester fabric.  We have tested a few cotton canvas bags in the market and realized that the shrinkage is significant after 1-2 washings. With a few more washings, the bags started to look like rags.  It is important to wash your shopping bags to get rid of dirt and food particles that might lead to unhealthy bacterial growth.   Clean Conscience reusable bags are made with a heavy duty woven fabric that washes and wears better than most cotton canvas bags, even after washing.