The first is the monopoly of upstream industry. For plastic (LLPDE and PP) and its source of raw materials mainly ethylene and propylene, its domestic raw materials 90% comes from sinopec and petrochina, there are a large part of the imports. In addition, LLDPE and PP existing capacity is about more than 70% and 60% respectively of petrochemical pair, or affiliated enterprise. Because the industry concentration is too high, rebound in crude oil, LLDPE and PP rebounding and time are relative to magnify. , of course, with the development of coal to olefin, the privatization of PP production capacity speed, to determine the, PP rally in the long run than LLDPE. In contrast, PTA and PVC as the proportion of private capacity relative to plastic, the spot market, PTA and PVC prices are relatively flexible, therefore, will not rise amplification, down type resistance characteristics.

The second is the raw material cost difference. From the point of cost, the sharp rebound in crude oil, in late February than in early February, ethylene and propylene prices rose 9% and 9% respectively. This makes the LLDPE and PP rallying on a substantial decline in the cost price. By comparison, PVC has two by calcium carbide method and ethylene process, under the condition of the domestic coal prices did not rebound, in process of domestic PVC production by calcium carbide method cost and no obvious increase, so this makes both belong to the general resin (plastic) PVC trend obvious weak in LLDPE and PP.

Finally the downstream application of different alternative. As a general purpose resins, LLDPE and PP on polluting plastics, injection molding and woven bags and no other alternative products, but the PVC and PTA downstream applications with TPE and cotton alternative respectively, so if do not have advantage in cost, it is relatively easy to be replaced. Methanol, due to the technology of methanol to olefins, at present are not possessed in the alternative.