METHODS FOR CONTROLLING POLYMER PROPERTIES IN POLYMERIZATION PROCESSES

Disclosed herein are methods of controlling polymer properties in polymerization processes that use a chromium-based catalyst. An embodiment discloses a method of producing a polyolefin comprising: contacting a reaction mixture and a reduced chromium oxide catalyst in a gas-phase reactor to produce the polyolefin, wherein the reaction mixture comprises a monomer and a co-monomer; and changing a reaction temperature in the gas-phase reactor by about 1 DEG C. or more whereby a gas molar ratio of the co-monomer to the monomer is changed by about 2% or more and a co-monomer content of the polyolefin at substantially constant density is changed by about 2% or more. Additional methods and compositions are also provided. 本文公开了控制在使用铬类催化剂的聚合过程中聚合物特性的方法。个实施例公开了种生产聚烯烃的方法，其包含：使反应混合物与还原型氧化铬催化剂在气相反应器中接触以生产聚烯烃，其中所述反应混合物包含单体和共聚单体；以及改变在所述气相反应器中的反应温度约1℃或更多，从而改变所述共聚单体与所述单体的气体摩尔比约2％或更多且改变基本上恒定密度的所述聚烯烃的共聚单体含量约2％或更多。还提供了另外的方法和组合物。