Preparation of polypropylene

The application of metallocene catalysis to the preparation of polypropylenes reached a commercial stage with the production by Exxon of their Achieve range in 1996 and in 1997 by Targor, the BASF-Hoechst joint venture with the introduction of Metocene. Such metallocene polypropylenes are, however, only a small proportion of the total polypropylene market, predicted at only about 3% of the total in 2005. 

With a rapidly growing market many grades of polypropylene are available but five main classes may be distinguished  

Two interesting developments should also be noted syndiotactic polypropylene produced by a novel metallocene system and polypropylene grafted with styrene and/or maleic anhydride marketed by Montell as Hivalloy. 

Mention should be made of the nomenclature for the polymer. Industrially the materially is invariably known in the English-speaking world as polypropylene. However, the lUPAC name for the monomer is propene and until 1975 the recommended lUPAC name was polypropene, a term very rarely used. The latest lUPAC rules base the name of a polymer on the constitutional repeating unit, which in this case is a propylene unit (c.f. a methylene unit for polyethylene) and this leads to the name poly(propylene) (i.e. with brackets). In this volume the more common, unbracketed but still unambiguous name will be used. 

In the suspension process, which was the first method to be commercially developed, propylene is charged into the polymerisation vessel under pressure whilst the catalyst solution and the reaction diluent (usually naphtha) are metered in separately. In batch processes reaction is carried out at temperatures of about 60°C for approximately 1-4 hours. In a typical process an 80-85% conversion to polymer is obtained. Since the reaction is carried out well below the polymer melting point the process involves a form of suspension rather than solution polymerisation. The polymer molecular weight can be controlled in a variety of 

---

CH2CHCH3, propene, the second member of the olefine series of hydrocarbons. It is the monomer used in the preparation of polypropylene and ethylene-propylene rubbers. 

Figure 7. Time-conversion plot for 1,5-pentanediol initiated preparation of polypropylene ether) diol in pentane (propylene oxide/pentane wt ratio = 3) with Zns[Co(CN)6]2 glyme ...

The preparation of polypropylene and the method of evaluation have been given (18). Relative activities (Ar) were determined from values of to. 3 and are referred either to hydroquinone as a standard (A,.,) or to pyrocatechol (Arz). 

Preparation of Polypropylene-g-Perfluoroacrylate Nonwoven Fabric with a Hydrophobic/Oleophobic Repellent Surface... 

FIGURE 6.17 Process steps in preparation of polypropylene regrind. 

There are several process requirements for the preparation of polypropylene staple with permanent three-dimensional helical curvature. Specifically, a rectangular spinneret-pack assembly is used to produce flow perturbation and to impart high internal stress. A specially designed cooling device cools the fiber quickly to form a paracrystalline structure in the fiber. The process principle is that the flow perturbed in the polypropylene melt creates internal stress on one side of the fiber section. Because of the stress memory of polypropylene, the internal stress difference at the interface of streamlined and perturbed flows can sustain in the fiber after it has been cooled and solidified. This leads to different crystal structures and shrink properties, and thus a fiber in the shape of a three-dimensional helix. 

Preparation of Polypropylene Nanocomposites Using Supercritical Technology... 

Mulhaupt and coworkers have reported the details of several studies related to the preparation of block copolymers from thiol, maleic acid and hydroxy-functional polypropylene prepared by a metallocene catalyst [157, 158]. The same group also reported the transformation of metallocene-mediated olefin polymerization to anionic polymerization by a novel consecutive chain-transfer reaction for the preparation of polypropylene-based block copolymers [159]. The latter were also... 

Rzayev, Z. M. O., Yilmazbayhan, A., and Alper, E. 2007. Aone step preparation of polypropylene-compatibilizer-clay nanocomposites by reactive extrusion. Advance Polymer Technology 26 41-55. Ho, R. M., Su, A. C., Wu, C. H., and Chen, S. 1993. Functionalization of polypropylene via melt mixing. Polymer 34 3264—3269. 

Yang, K., Huang, Y., and Dong, J.-Y. 2007. Preparation of polypropylene/montmorillonite nanocomposites by intercalative polymerization Effect of iw situ polymer matrix functionalization on the stability of the nanocomposite structure. Chinese Science Bulletin 52 181-187. 

Xia, H., Wang, Q., Li, K., and Hu, G. H. 2004. Preparation of polypropylene/carbon nanotube composite powder with a solid-state mechanochemical pulverization process. Journal of Applied Polymer Science 93 378-386. 

Ma, J., Bilotti, E., Peijs, T., and Darr, J. A. 2007. Preparation of polypropylene/sepiolite nanocomposites using supercritical C02 assisted mixing. European Polymer Journal 43 4931-4939. 

U.N. Ratnayake, B. Haworth, D.J. Hourston, Preparation of polypropylene-clay nanocomposites by the co-intercalation of modified polypropylene and short-chain amide molecules. Journal of Applied Polymer Science 112 (1) (2009) 320-334. 

Ihe literature " describes a number of dendrimers and the closely related star-like 120-123 polysiloxanes. Ihe hyperbranched polysiloxanes are the primary example of more random structures. Although the emphasis has been on synthesis and characterization,i i modeling on hyperbranched polymers has also been carried out. Some of the most interesting species involve polysiloxane chains. Star polymers, some with nanosized silica cores, have also been synthesized.i °-i i Hyperbranched polysiloxanes have been prepared with controllable molecular weights and polydispersities,i -1 - with epoxy terminal groups some are UV-curable ° and some serve as a source of molecular silica. Hyperbranched polysiloxanes have also been used in the sol-gel preparation of polypropylene/silica nanocomposites. ... 

For polyolefins and their composites, is the preferred method for large-scale industrial production with metallocene catalysts. Successful in-situ preparation of polypropylene nanocomposites by GASP technique has been mentioned in earlier reports [64]. 

Polypropylene glycol ethers can be synthesized by adopting epoxy alkyls and related alcohol as raw materials. For example, the preparation of polypropylene glycol from etherepoxy ethane can be given as follows ... 

---