Polypropylene self-reinforced

Recycling more effective solutions are sought. The development of the mono-material concept is favourable to thermoplastics and self-reinforcing thermoplastic composites such as self-reinforced polypropylene (Curv from BP). 

Underbody parts in self-reinforced polypropylene (Curv) for the Audi A4. 

Table 6.27 compares some self-reinforced polypropylene properties with those of other general-purpose solutions. 

The (property/density) ratios show that the self-reinforced polypropylene is comparable to the general-purpose GMTs with a much higher impact resistance ratio. 

Other self-reinforced polymers are being developed. For example, PURE is based on highly oriented co-extruded tapes of polypropylene and a consolidation binder. Properties vary according to the form (see Table 6.27) - sheets, tapes or fabrics. 

Table 6.27 Examples of self-reinforced polypropylene properties compared to other general-pnrpose solutions...

Examples of properties of self-reinforced polypropylene tapes and sheets ... 

Aurrekoetxea J. Sarrionandia M. Mateos M Aretxabaleta L. (2011) Repeated low energy impact behaviour of self-reinforced polypropylene composites. Polymer testing. Vol.30, Issue. 2, pp. 216-221. 

Ward and his coworkers investigated the interlayer adhesion in self-reinforced PP composites modified with different nano- and micron-sized particles [27-29]. They found that the introduction of a small amount of carbon nanofibers (CNFs) led to improved performance of polypropylene single-polymer composites obtained by hot compaction of oriented CNF/ PP tapes. The peel strength of a CNF/PP woven fabric composite was significantly increased. In addition, the authors pointed out that the drawn CNF/PP tapes showed substantial voiding around the fibers which were closed and sealed by the hot compaction process. As a result, the composite density increased to its initial value [27]. 

In a previous work, the same authors also observed that the composite peel strength was significantly increased by introducing interleaved films of the same polymer between the layers of woven oriented tapes [30]. They continued working on PP self-reinforced composites enhanced with the addition of CNT, trying to improve properties by the use of interleaved films [28]. Samples of single-polymer polypropylene composites were produced with and without interleaved films, and with and without carbon nanofibers, located either in the oriented polypropylene tapes, in the interleaved film or in both. Maximum peel strength was observed... 

It is an important component of polypropylene, alone or with talc, for rigidity and whiteness that resists weathering. Metallocene-produced polypropylenes, with greater self-reinforcement, can tolerate higher loadings, for better whiteness. 

Armordon is also a polypropylene based self-reinforced plastic manufactured by Don Low Ltd. The production process is similar to the production of PURE and combines two different types of PP ensuring a strong affinity between the two components of the tape. Further processing steps may use the tapes directly for winding or tape placement processes or they can be woven into fabrics. Typical applications can be found in the security industry as armor, since Armordon shows an excellent ballistic performance. Additionally, applications in the automotive sector and consumer products such as luggage are imaginable. 

Barany T, Izer A and Czigany T (2006) On consolidation of self-reinforced polypropylene composites, Plast Rubber Compos 35 375-379. 

Kim K J, Yu W-R and Harrison P (2008) Optimum consolidation of self-reinforced polypropylene composite and its time-dependent deformation behavior. Compos Part A 39 1597-1605. 

Izer A, Stocchi A, Barany T, Pettarin V, Bernal C and Czigany T (2010) Effect of the consolidation degree on the fracture and failure behavior of self-reinforced polypropylene composites as assessed by acoustic emission, Polym Eng Sci 50 2106-2113. 

Self-reinforced all-polypropylene (SR-PP) composites are impressive with their excellent basic mechanical characteristics, which are combined with an extremely low weight. From a processing-technological point of view, a high standard of precision is mandatory for manufacturing in order to ensure that the essential self-reinforcement of the polymer is successfully transferred to the later composite. 

Table 22.1 compares properties of conventional reinforcing fibers, self-reinforced polypropylene fibers and compact polypropylene semifinished products, which are described in literature. 

Compared to glass fiber and other foreign fiber reinforced polypropylenes, prominent characteristics are an exceptionally high impact strength and resistance to perforation [26,76]. These are caused by an efficient absorption of energy by self-reinforced fiber composite systems. 

In addition, self-reinforced fiber composites are far superior to glass and carbon fiber materials with regard to their energy consumption during production and recycling because of the low melting point of polypropylenes. Table 22.2 shows the comparison. 

On the whole, self-reinforced polypropylene fiber composites incorporate both features of unreinforced and of reinforced plastics in their property sprectrum. A high macromole-... 

Self-reinforced polypropylene fiber composites that are real organic sheets are conquering application fields common for both unreinforced and reinforced plastics due to their excellent property spectrum. Their high macromolecular orientation, which is induced by means of stretching, can be transferred via a composite structure into light and stiff plain structural components. 

Bdrdny T, Izer A and Czigdny T (2007) High performance self-reinforced polypropylene composites, Mater Set Forum 537-538 121-128. 

Bhrhny T, Karger-Kocsis J and Czigdny T (2005) Development and characterization of self-reinforced polypropylene composites, in Proc 8 Polym Adv Technol Int Symp, Sept 13-16, Budapest, Hungary, pp. 1-3. 

Izer A, Bdrdny T, Varga J (2009) Development of woven fabric reinforced aU-poljqaropylene composites with beta nucleated homo- and copolymer matrices, Compos Sci Technol 69 2185-2192. Bdrdny T, Izer A and Czigdny T (2006) On consolidation of self-reinforced polypropylene composites, Plast, Rubber Compos 35 375-379. 

McKown S and Cantwell W J (2007) Investigation of strain-rate effects in self-reinforced polypropylene composites, J Mater Sci 41 2457-2470. 

Bledzki A K, Ries A, Passmann D and Heim H-P (2010) Impact Behaviour of Property Graded Self-reinforced Polypropylene Composites, Proc of SAMPE Europe SEICO10 Techn Conf, Apr 12-14, Paris, France, pp 354-359. 

Bledzki A K, Passmann D and Ries A (2011) Functional graded self-reinforced polypropylene... 

Guan Q, Zhu X, Chiu D, Shen K, Lai F S and McCarthy S P (1996) Self-reinforcement of polypropylene by oscillating packing injection molding under low pressure, J Appl Polym Sci 62 755-762. 

Chen L and Shen K (2000) Biaxial self-reinforcement of isotactic polypropylene prepared in uniaxial oscillating stress field by injection molding. II. Morphology, J Appl Polym Sci 78 1911-1917. 

Table 3 Mechanical properties of polypropylene-based self-reinforced polymer composites, as described in the literature... 

Fig. 16 Effect of processing condititms rat the deformation of self-reinforced polypropylene tape-based composites following penetrative impact, (a) Specimen was consolidated at lower temperature and pressure and shows large amounts of ont-of-plane deformation and tape pull-through, (b) Specimen was consolidated at a higher temperature and pressure and shows very localised damage and limited out-of-plane deformatimi. Reproduced with kind permission from Elsevier from [160]...

Jones RS, Riley DE (2002) A new self-reinforced polypropylene composite. In Proceedings 2nd annual conference of Society of Plastics Engineers, Automotive and Composites Division Composites, global technologies for better vehicles, Michigan, USA... 

Hayes H (2008) Self-reinforced polypropylene composites - a new class of material for the motorsports industry. In Motoisports Engineering Conference, Concord, North Carolina, USA... 

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