Polypropylene (PP) is trading lower while PVC and polystyrene prices have increased in North America.  PP dropped about 6 cents in March after dropping about the same in February, essentially wiping out the gains made in January.  This swing tends to show a great volatility in the pricing of PP. Winter weather affected the production up to January causing the price increase and we hope to see a stabilization of the PP market for the rest of the year, but with the PP demand lower, this could see prices drop even lower. 
Polystyrene prices rose a total of 6 cents over the last two month as a result of production problems. PS sales are down overall, but exports have helped reduce the deficit.
PVC prices have increased over the last two month after being almost flat for the previous two months. Stronger prices are the result of increased exports and lower production outputs while domestic (US/CAN) sales have increased.