The shrinkage rate control/preparation of PP polypropylene modified material is an important aspect of polypropylene modification. The good shrinkage rate control/manufacturing is of great significance to the promotion and use of polypropylene modified materials, and it is also an important factor to ensure product quality. In particular, the application of modified polypropylene to replace traditional engineering plastics, shrinkage rate is very important. The following Jia Lixin modified PP will be described in terms of minerals, glass fiber, polyethylene, molten fat, etc. The effect of shrinkage.
Effect of Mineral Filling on Molding Shrinkage of Polypropylene PP Modified Plastics
The mineral additives used in polypropylene PP are mainly calcium carbonate, talc powder, mica powder, etc. The effect of various mineral fillers on the shrinkage of polypropylene molding can be seen from the molding shrinkage of mineral fillers for PP modified materials. The influence is obvious. The influence of mineral filler on the shrinkage of polypropylene modified material has three main aspects: First, the mineral filler itself does not shrink, and its addition reduces the shrinkage of polypropylene modified material from the overall proportion. The second is that the addition of the mineral filler will inevitably affect the crystallinity of the polypropylene, thereby affecting the shrinkage rate; the third is the addition of a fine mineral agent, which acts as a nucleating agent and changes the structural state of the polypropylene. The formation of anti-large spherulites also affects the molding shrinkage of polypropylene.
Effect of Glass Fiber on Molding Shrinkage of Polypropylene PP Modified Plastics
Glass fiber has the greatest influence on the molding shrinkage of polypropylene PP modified material. When the content of glass fiber reaches 30% or more, the molding shrinkage of polypropylene modified material decreases from 1.8 to 0.5, and the surface treated glass The influence of fiber on the molding shrinkage is greater than that of untreated glass fiber. The addition of glass fiber breaks the crystallinity of polypropylene, affects the shrinkage rate, and more importantly, the fiberglass limit/crystal shrinkage of polypropylene.
Effect of polyethylene addition on shrinkage of polypropylene molding
The addition of polyethylene also affects the molding shrinkage of polypropylene modified materials. Although polyethylene is also a high crystallinity plastic, the molding shrinkage is also large, but it is broken or broken to varying degrees after being added to polypropylene. Their respective crystallinity reduces the overall molding shrinkage.
Effect of changes in polypropylene's own MI (molten fat) on molding shrinkage
The molding shrinkage of polypropylene is affected by its crystallinity, and the crystallinity is affected by its own molecular weight. When MI increases, the molecular weight decreases, its crystallization rate increases, and the molding shrinkage increases. When changing, it also has a certain influence on the molding shrinkage rate.
Personal experience 1: Glass fiber, minerals, elastomers, polyethylene, MI The order of influence on the shrinkage of PP modified plastics is: Fiberglass > Minerals > Elastomers > Polyethylene > MI. 2: Change of polypropylene 2. Crystallinity is the key to the shrinkage of the controlled / polypropylene modified material.