Polypropylene processing properties

Very active, not too expensive, catalysts may be left in the product if they are used in such small quantities that they are not detrimental to the properties of the product. An example is the gas-phase polypropylene process. When the desired product is formed as a solid, i.e. crystallizes from the homogeneous reaction mixture, the product can be removed in relatively simple way. 

The dyeing of polypropylene fibers, being an item of research for decades, is successfully accomplished with partially stearate-modified hyperbranched polyesteramides. The long alkyl chains ensure compatibility with the polypropylene matrix. The mixing-in of hyperbranched polyesteramides via extrusion affected neither the melt spinning process nor the final polypropylene fiber properties. The modified fibers are dyeable under standard conditions as are, e.g., polyesters or cotton. They can even be used for printing for example a picture pattern on a polypropylene carpet. 

Nucleating agents not only shorten the time of crystallization but also improve the mechanical properties of materials. Polypropylene processed with a nucleating agent (2% CaCOs) had its impact strength and modulus increased by 50%. ... 

An alternative approach to uaiproving radiation stability has been through coupling the desirable processing properties of polypropylene with the radiation stability of polyethylene to form copolymers (polyallomers). Block polymers in which the chains comprise polymerized segments of each of the monomers are as amenable to processing as polypropylene while having better clarity and radiation stability. 

Albert KA et al (1993) Acrylic modified polypropylene for thin-gauge thermoforming improved processing properties and economics. J Plast Film Sheeting 9 293-305, October... 

Varga, J. (2002). Beta-modification of isotactic polypropylene Preparation, structure, processing, properties, and apvplication.. Macromol Sci, Phys. B., Vol. B41, Issue 4-6, pp.1121-1171. 

Polypropylene Structure, Properties, Manufacturing Processes, and Applications... 

In rolled (see the chapter entitled Rolltrusion processing of polypropylene for property improvement) sheet, the c- and fl -axes are mixedly oriented in the rolling direction and the h-axes are random about it. With increasing compression ratio, the molecular orientation increases and the crystallinity decreases, resulting in an increase in the tensile modulus and a decrease in the elongation. 

Alcock B (2004) Single poljoner composites based on polypropylene processing and properties, PhD Thesis, Queen Mary, University of London, London, UK. 

Polypropylene s properties are decisively determined by the applied polymerisation process and the catalysts used. As shown in Figure 3.5, the base unit of PP consists of three carbon and six hydrogen atoms. 

Processing properties of syndiotactic polypropylene have been improved by blending with isotactic polypropylene. It has allowed a syndiotactic polypropylene-based polymer to process well with conventional processing machines in conventional operating conditions. The transparent articles with moderate rigidity can be... 

---