PP-rayon

In the present chapter, rayon and other man-made cellulose fibers wUl be introduced in terms of properties and stracture. The compounding method to obtain the composites will be described briefly. PP-rayon composites will be considered in more detail as the practically most relevant class of this type of material at present arousing interest from the automotive industry. In another section rayon composites with poly(lactic acid) (PLA) and polyhydroxyalkanoates (PHA) will be studied as a promising bio-based and biodegradable alternative to conventional materials in durable applications, transport, and automotive industry. Finally, some concluding remarks will be given concerning future prospects of rayon reinforced thermoplastics and the problems to be tackled in future work. 

Fig. 18.14 Tensile strength and modulus, Charpy unnotched and notched impact strength for PP, and PP-rayon composites without and with 3% CA...

A more systematic study on jute admixtures to PP-rayon composites has been performed by Khan et al. [24]. Coupled PP composites with an overall fiber content of 25 wt% and varying proportions of native and NaOH-treated (mercerized) jute fibers mixed to rayon were produced and tested. Generally, mercerized jute fibers showed better performance and a jute fraction of 20 wt% produced the most favorable properties. 

Fig. 18.15 Coirelalion between single fiber elongation left) and coupled PP-rayon composite elongation at break (right) from Ganster et al. [25]...

C. R. Woodings, "The Development of Viscose Rayon foi Nonwoven Appheations," TAPPI Nonwovens Fibres Seminar 1979, pp. 15—28. 

The structure of PP-g-polystyrene was studied by wide and narrow angle x-ray diffractometry. The polystyrene component formed discrete amorphous structures, which were identified after chloromethylation [143]. Structure of Rayon-Styrene graft copolymer was characterized by IR, wide angle x-ray, and SEM, grafting occurred mainly in the amorphous regions of rayon [1441. 

Debrenne PP, Laugier J, Chaudet M (1970) Diffractometre de rayons X a haute temperature (2500 C) sous vide pousse (10-8 Torr). J Appl Crystallogr 3 493 96... 

Refs. [i] Timashev SF (1993) Zh Fiz Khim 67 1755 [ii] Timashev SF (2001) Russ J Phys Chem 75 1742 [Hi] Timashev SF (2001) Flicker-noise spectroscopy as a tool for analysis of fluctuations in physical systems. In Bosman G (ed) Noise in physical systems and 1/f fluctuations. ICNF, World Scientific, New Jersey, pp 775-778 [iv] Timashev SF, Vstovskii GV (2003) Russ JElectrochem 39 141 [v] Parkhutik V, Patil R, Harima Y, Matveyeva E (2006) Electrochim Acta 51 2656 [vi]Parkhutik V, RayonE, FerrerC, TimashevS, Vstovsky G (2003) Phys Status Solidi A Applied Research 197 471... 

American Viscose Corp., Rayon Technology, pp. 236-51, New York, McGraw-Hill Book... 

J. Bergonie Les rayons X et leurs applications medicales. Revue philomatique de Bordeaux et du Sud-Ouest (1900), pp. 49-68. 

E Bjorkman, O Samuelson, E Ringstrdm, T Bergek, E Malm. Decay injuries in spruce forests and their importance for the production of chemical paper pulp and rayon pulp. Kgl Skogshogskolan Skr No. 4, Stockholm, 1949, 73 pp. 

Morrison s text in All the Comforts of Home was primarily didactic, consisting of a long list of consumer goods such as rayon ( better than silk ) or aniline dyes ( better than natural dyestuffs ) that were the product of chemical industry. Morrison tells the reader that Americans use the most soap in the world, at 27 pounds per person annually. This beats out other clean countries such as Holland, Germany, and England. The Chinese were the least clean people, using only six ounces of soap each per year (ibid., pp. 165-6). This brief passage establishes a clear hierarchy of nationalism, with the United States at the top (clean and industrial) and China at the bottom (dirty and unindustrialized). 

Carbon disulfide is a volatile organic solvent, used mainly as a starting material in rayon manufacture in the viscose process. It was important historically in the cold vulcanization of rubber. Although no longer used in this form, carbon disulfide is still a major industrial precursor in rubber industry chemical synthesis and has a number of other industrial applications. Carbon disulfide is also widely used as a solvent in a variety of laboratory settings. Carbon disulfide is a metabolite of the drug disulfiram (see pp 186) and is a spontaneous breakdown by-product of the pesticide metam sodium. 

In principle, all the fiber ty pes described above can be used advantageously for reinforcing thermoplastic matrix materials to improve their mechanical and thermomechanical properties. This has been demonstrated for PP as matrix material [7]. In what follows, however, the focus is put on rayon tire cord yam, as it has favorable properties (cf. Table 18.1) and is commercially available as a technical (endless) filament yam with suitable yam titre. 

Fig. 18.4 Homogeneity of fiber distribution in rayon reinforced PP SEM (left) and optical right) micrographs (from Ganster et al. [12] with permission from Elsevier)...

The quality of fiber distribution obtained by this method is demonstrated in Fig. 18.4, where an SEM micrograph (left) and an optical micrograph of a 10 pm thick slice cut through an injection molded rayon reinforced PP sample perpendicular to the molding direction are shown. 

Fig. 18.5 Fiber length distribution in rayon-PP composite injection molded test bar with 25% fiber content, 3 mm cut length during processing...

Fig. 18.9 SEM cryo fracture micrographs for uncoupled left) and coupled right) rayon-PP composites [3 wt% PP-g-MAH coupling agent, from Ganster and Fink [7]]...

Fig. 18.10 Tensile and bending strengths and moduli of rayon-PP composites coupled with...

Fig. 18.11 Tensile strength and modulus for rayon-PP composites with 20% rayon as a function of coupling agent PP-g-MAH concentration...

Unnotched and notched Charpy impact strengths at room temperature and at — 18°C for rayon-PP composites coupled with 3 wt% PP-g-MAH are shown in Figs. 18.12 and 18.13, respectively, as a function of fiber volume fraction. 

The use of CAs has important consequences for the impact properties of the composites as demonstrated for the PP matrix in comparison to a PP composite with 30 wt% rayon without and with 3% CA in Fig. 18.14. Strength and modulus are changed as in Fig. 18.11, but unnotched impact strength is improved by the CA while notched impact strength is reduced. 

With 25% pure rayon, a moderate increase to 80°C can be obtained, as shown in Table 18.3. In this table, the HDT-A values for pure PP and cellulose man-made fiber-based composites are given together with other important mechanical characteristics. In order to increase the HDT to more than 100°C, three routes were pursued (1) change the cellulose fiber type from rayrai to Lyocell, (2) use fiber mixtures with natural fibers or LyoceU, and (3) add organic fillers (like talcum) to the matrix. 

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