聚合物共混物的相容性原则

Principle of compatibility of polymer blends

聚合物组分之间的共混改性，为达到改善性能的相应效果，往往需要加入相容体系。一般来说，不同聚合物组分之间的共混需要的是相适应的相容性，从而制得相相之间结合力较强的多相结构的共混物。了解与应用共混物体系之间的更好相容性，应考虑如下几个原则。

In order to improve the performance, the blending modification between the polymer components often needs to be added to the compatibility system. Generally speaking, the compatibility between different polymer components needs compatible compatibility, so that the multiphase structure with strong adhesion between phases is obtained. The following principles should be taken into account to understand the better compatibility and application of blends.

（1）溶解度参数相近原则

(1) the principle of solubility parameter close

聚合物之间的共混过程，实际上是分子链间相互扩散的过程，并受分子链之间作用的制约。分子链间相互作用的大小，可以用溶解度参数来表示。溶解度参数的符号为δ，其数值为单位体积内聚能密度的平方根。不同组分之间的相容性好坏，也可以用溶解度参数δ之差来衡量，即δ越接近，其相容性越好。

The blending process between polymers is actually a process of mutual diffusion between molecular chains, and is restricted by the interaction between the molecular chains. The size of intermolecular interactions can be represented by solubility parameters. The symbol of the solubility parameter is delta, and its value is the square root of the density of energy in the unit volume. The compatibility between different components can also be measured by the difference of the solubility parameter [delta]. That is, the closer the delta is, the better its compatibility.

如两种聚合物溶解度参数相近，其差值通常要＜0.2，而两种聚合物溶解度参数之差＞0.5时，不能以任意比例相容。例如：PVC/NBR共混体系，PVC的溶解度参数δA为9.4～9.7，而NBR的溶解度参数δB为9.3～9.5，所以PVC与NBR相容性良好；又如PS/PB共混体系，他们的溶解度参数之差＞0.7，所以两者的相容性差。PVC与PS的溶解度参数之差＞1，所以两者基本不相容。

If the solubility parameters of the two polymers are similar, the difference is usually less than 0.2, and when the difference of the solubility parameters of the two polymers is 0.5, it can not be compatible with any proportion. For example, PVC/NBR blend system, PVC solubility parameter A is 9.4 ~ 9.7, and NBR solubility parameter B 9.3 ~ 9.5, so PVC has good compatibility with NBR, and PS/PB blend system, their solubility parameter difference is more than 0.7, so their compatibility is poor. The difference between the solubility parameters of PVC and PS is more than 1, so they are basically incompatible.

（2）极性相近原则

(2) the principle of polarity close

聚合物之间共混体系的极性越相近，其相容性越好，即极性组分与极性组分、非极性组分与非极性组分都具有良好的相容性。例如：PVC/EVA、PVC/NBR、PVC/ABS之间极性相近，所以其相容性好。在考虑共混改性配方设计时，要了解聚合物之间相容性的基本原则：极性/极性≥非极性/非极性≥极性/非极性。极性组分与非极性组分之间一般不相容，例如：PVC/PC、PVC/PS、PC/PS等。

The closer the polarity of polymer blends, the better their compatibility. That is, polar components have good compatibility with polar components, non-polar components and non-polar components. For example, the polarity of PVC/EVA, PVC/NBR and PVC/ABS is similar, so its compatibility is good. In considering the blending formula design, to understand the basic principles of polymer compatibility: polar / nonpolar / polar or nonpolar or polar / nonpolar. Polar components and non polar components are generally incompatible, such as PVC/PC, PVC/PS, PC/PS and so on.

极性相近原则也有些例外，例如：PVC/CR共混体系，其极性相近，但不相容；而PPO/PS两种极性不同的组分，相容性反而很好。

There are some exceptions to the principle of polarity similarity. For example, PVC/CR blend system has similar polarity but is incompatible, while PPO/PS two components with different polarity have good compatibility.