Nucleating agents / clarifiers

There appears to be no physical (e.g., crystal habit or morphology) or chemical (e.g., surface groups) correlation to identify which nucleating agent works best with which polymer matrix. However, it is known that dibenzylidene sorbitol works best with PP (it is sometimes called a clarifier because it enhances transparency), and inorganic benzoate salts are successful with PET. 

Many industrial semi-crystalline polymer materials like polypropylene, polyamides, or polyesters contain nucleating agents or clarifiers which form needle-shaped aggregates already in the polymer melt. "For this purpose the pattern is desmeared using the measured primary beam. For a less involved treatment it may be sufficient to know the integral width of the primary beam profile in fiber direction. 

Polypropylene can have its clarity and transparency improved by orientation, or by use of clarifying/nucleating agents. 

Nucleation and clarity 10 High crystallization and processing rates, high haze in cloudy PE and PP Nucleating agents for higher properties, clarifying nucleators for clearer PP containers... 

Table 10.1 Summary of Nucleating and Clarifying Agents Discussed in this chapter...

Strength and modulus Fundamental tests for strength and stiffness, along with HOT testing, reveal to what extent a clarifier also serves as a useful nucleating agent. 

Early clarifying and nucleating agents sometimes resulted in difficult ejection from the mould, or gave rise to organoleptic problems. The suppliers have addressed these issues in recent years. 

Figure 6.5. Effect of nucleating agent content on the peak temperature of crystallization of iPP. (O) poly(vinyl cyclohexane), ( ) clarifier (sorbitol derivative) Millad 3988, (A) NA 21 E. [Adapted, by permission, from Menyhard, A Gahleitner, M Varga, J Bemreitner, K Jaaskelainen, P Oysaed, H Pukan-szky, B, Eur. Polym. J., 45, 3138-48,2009.]...

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