Masterbatch process

Fig. 1.9 (A) Exfoliation of clay platelets (white Cloisite25A and Cloisite30B after (B) two and a arrows) in a commercial polylactide matrix using half months hydrolysis and (C) after five and a a masterbatch process. (B, C) Visual aspect half months hydrolysis. (A) adapted from [144] of unfilled PLA, microcomposite based on reproduced by permission ofWiley-VCH, and CloisiteNa+, and nanocomposites based on (B, C) from [147] with permission from Elsevier.

Masterbatch process involves plasticizers and it is an example of help which can be expected from plasticizers in the compoimding process. Masteibatching helps to solve several important problems in compoimding good wetting, reduced viscosity, inert dispersing medium, improved distribution of additives added in small quantities, increased... 

R. K. Shah and D. R. Paul, Nylon 6 nanocomposites prepared by a melt mixing masterbatch process. Polymer, 45 (2004), 2991-3000. 

Carbon blacks are incorporated into polymeric media by one of two methods. The proper amount of carbon black may be dispersed directly into the polymer using a suitable mixing device. Far more common, however, is the masterbatch process in which carbon black is first dispersed into a carrier resin in concentrations of 30-50%. This concentrate is then let down (diluted) via the salt and pepper procedure attained by introducing a mixture of concentrate and polymer pellets into the mixing unit. The ratio of compound to pellets is adjusted to provide for the final carbon black loading. 

Wichmann MHG, Sumflesh J, Fiedler B, Gojny FH, Schulte K. Multiwall carbon nanotube/epoxy composites produced by a masterbatch process. Mech Compos Mater 2006 42 395-406. 

Accordingly, a two-step method, named masterbatch process, has been approached for the preparation of PCL layered silicate nanocomposites by combining the in-situ intercalative polymerization and the melt blend intercalation process d. In such a process, a highly clay-filled (organo-modified) PCL is first prepared by in-situ intercalation pol)mierization of e-CL, followed by its addition as masterbatch, that is blended with the molten polyester matrix (commercial PCL CAPA 650). As it will be shown, this method permits to prepare PCL-based nanocomposites with a high degree of exfoliation, which cannot be achieved by directly mixing PCL and clay. 

The elastic modulus is improved from 217 MPa for unfilled PCL up to 365 MPa for the nanocomposites (filled with 10 wt% Cloisite Na" prepared by the masterbatch process. In contrast, the microcomposites prepared by direct melt blending with Cloisite Na showed only very limited increase in stiffriess. 

The thermal stability of PCL-based nanocomposites prepared by masterbatch process has been studied by TGA (at 20 °C/min.). All these nanocomposites have a degradation temperature higher than neat PCL and this improvement in thermal stability is slightly greater than for the composites obtained by direct melt blending. 

Thus, the temperature at which 50% weight is lost shifts by about 50 °C to higher temperature when 3 wt% of inorganic filler is added. The thermal degradation has been studied also as function of the clay content in the final nanocomposites prepared via the masterbatch process. As far as Cloisite 30B is concerned, the temperature at which 50% weight loss is recorded shifts by about 65 °C to higher temperature at a clay content as low as 1 wt%. However and even if some enhanced thermal stability is still observed, this beneficial effect continuously decreases upon increasing the clay content. This thermal behaviour is very similar to that already observed for PCL-based nanocomposites prepared by direct melt intercalation. 

The masterbatch process allows to obtain PCL intercalated silicate nanocomposites, even with natural Cloisite Na , and it even leads to partially intercalated/partially exfoliated structure when using a masterbatch filled with Cloisite 30B. Stiffness of PCL nanocomposites is significantly improved as compared to microcomposites directly prepared by melt intercalation. As expected, the thermal stability of these nanocomposites is... 

Finally, by its easiness of processing (simple addition of the filler during the extrusion process), the masterbatch process presents a good potential for fiuther industrial applications. 

Interestingly enough, both synthetic pathways have been successively combined to each other, via the so-called masterbatch process. It consists of... 

Ecolyte later developed a masterbatch process for polyethylene in which MIPK was grafted to a low-density polyethylene substrate. This was produced for agricultural applications and the film was produced by Atlantic Packaging Limited of Toronto. The plastic film was sold mainly for farms in Florida growing melons and tomatoes. Atlantic found it difficult to compete with local producers who used recycled material. The masterbatch was later also marketed by Eco Atlantic in Baltimore, Maryland. 

Lepoittevin B, Pantoustier N, Devalckenaere M, Alexandre M, Calberg C, Jerome R, Henrist C, Rulmont A, Dubois Ph (2003), Polymer/layered silicate nano-coomposites by combined intercalative polymerisation and melt intercalation a masterbatch process . Polymer, 44, 2033-2040. 

---