Yes and no!
PVC is a mixture of ingredients and there are infinite recipes. One of the main and most expensive ingredients is titanium, and some extruders who want a cost-effective PVC will reduce its amount. Unfortunately, this type of PVC will tend to yellow over time (sunburn).
At P.H. Tech, we constantly strive to improve our PVC recipe in an effort to ensure optimal quality over the product's entire lifespan… which is more than 20 years! For this reason, we regularly perform accelerated-aging tests, in specially-designed machines as well as in Florida and Arizona. This is why we know that our PVC, if it yellows, will be unnoticeable.
Note that at the time of purchase, there will be no visible difference between inexpensive PVC (that will yellow from sunburn over time) and high-quality PVC. To avoid falling into this trap, be sure to ask you retailer for a PVC product from P.H. Tech!