Polypropylene clarifying/nucleating

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

Manolis Sherman L. New clarifiers nucleators they make polypropylene run clearer and faster. Plastics Technol [trade journal (www.ptonline.com)— Gardner Publications] 2005 (downloaded 27 November 2006). 

Clarifying/nucleating agents For polypropylene increase rate of crystal initiation, improved clarity, better flow, faster set-up... 

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 blown film which has excellent optical and mechanical properties was obtained using nucleating agents. The polypropylene composition contains a clarifier selected from the group of aromatic phosphoric acid ester metal salts and almniniitm-hydroxy-bis[2,2 -methylene-bis(4,6-di-t-butylphenyl)phosphate] in the qirantities from 0.01 to 5 wt%. ... 

Polypropylene nonwovens or yams are produced by extruding a mixture of polypropylene and P-nucleating agent or certain clarifiers to form the improved polypropylene filaments." The P-nucleating agent comprises at least one of N, N -dicyclohexy 1-2,6 naphthalene dicarboxamide and NJ-Star NU-lOO from Rika."... 

Fig. 5 Crystallite sizes in polypropylenes produced with an ansa-zirconocene catalyst (left) and with a solid-state Ziegler-Natta catalyst (right), both clarified with a nucleating agent (Courtesy of Basell Polyolefins GmbH and of Rendiconti Lincei Scienze Fisiche e Natural for permission to reproduce this figure from [66])...

The first three materials listed in Table 11.6 are amorphous thermoplastics. CR-39 is a cross-linked, amorphous network (see Section 17.2). Most highly crystalline polymers are hazy because the crystals and the amorphous phases do not have the same index of refraction and light is scattered at the interfaces. Poly(4-methyl-l-pentene) is unusual in that the two phases have nearly the same index of refraction. The haze in crystalline polymers can be reduced if the crystallite size is very small. A sorbitol-based clarifier for polypropylene is bis(3,4-dimethyldibenzylidene) [25]. It acts as a nucleating agent and makes it possible to produce a water bottle with PET-like clarity. 

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