Indian polymers except for polystyrene (PS) have surged by as much as 12% in the past month largely due to production cuts that limited supply to the market, but the gains may not be sustained in the second quarter, industry sources said on Tuesday. Low inventories coupled with restricted availability allowed polyethylene (PE) and polypropylene (PP) to gain about $90/ton last Friday to $800-950/ton CFR (cost and freight) India from a month earlier. Over the same period, polyvinyl chloride (PVC) also inched up $40/ton to $670-690/ton CFR India, while PS fell by up to $80/ton to $720-880/ton CFR India.