Flour composition mechanism

Hongsprabhas, P. and Dit-udom-po, S. 2006. Influence of flour type on mechanical properties of calcium-induced egg albumen-flour composite gel. International Journal of Food Engineering 2(1), article 2. 

The above data show that fly ash was not beneficial for mechanical properties of the HDPE-wood flour-based composite. However, the flowability (MFI) of the molten composite was getting higher (viscosity was lower) when fly ash was replacing wood flour. Last but not the least, it was found that fly ash stabilized the HDPE-wood flour composition against heating. The onset of thermal decomposition for the 40% wood-flour-filled HDPE started at about 280°C, while that of 40% fly ash-filled HDPE started at approximately 490°C. The triple (HDPE-wood flour-fly ash) composite was between the two in this regard, showing a thermally more stable behavior than composites with wood flour alone [23]. 

V. Hristov, M. Krumova, and G. Michler. Influence of the excess coupling agent on the microdeformation processes and mechanical properties of polypropylene/wood flour composites. Macromol. Mater. Eng., 2006, 291, 677-683. 

H. Nitz, P. Reichert, H. Romling, R. Mulhaupt, Influence of compatibilizers on the surface hardness, water uptake and the mechanical properties of poly (propylene) wood flour composites prepared by reactive extrusion. Macromol. Mater. Eng. 276, 51-58 (2000)... 

Hristov V. N. Krumova M. Vasileva St. Michler G.H. Modified polypropylene wood flour composites. Fracture deformation and mechanical properties. Journal of Applied Polymer Science, vol.92, No.2, (2004), pp. 1286-1292... 

Yang HS, Kim HJ, Son J, Park FU, Lee BJ, Hwang TS (2004) Rice-husk flour filled polypropylene composites mechanical and morphological study. Compos Stmct 63 305-312... 

A. Hassan, A.A. Salema, EN. Ani, and A.A. Bakar, A review on oil palm empty fruit bunch fiber-reinforced polymer composite materials. Polym. Compos. 31(12), 2079-2101 (2010). M. Zaini, M.A. Fuad, Z. Ismail, M.S. Mansor, J. Mustafah, The effect of filler content and size on the mechanical properties of polypropylene/oil palm wood flour composites. Polym. Int. 40(1), 51-55 (1996). 

The problem of reinforcing PVC with fibres differs from that of polyolefins. This is because PVC needs another additive such as plasticiser, which should be added. The improvement in dispersion and adhesion between the wood particles and the polymer matrix showed that the mechanical strengths can be greatly enhanced, while the rheology or processing of thermoplastics/wood flour composites is seldom studied [34,35]. Recently, the effect of low levels of plasticiser on the rheology and mechanical properties of PVC/newsprint fibre composites has been reported [36]. 

Kevlar fibers can be used as reinforcement for wood-flour/high-density-polyethylene matrices to improve their mechanical properties. The study of Ou et al. [112] demonstrates that the addition of a small amount (23%) of Kevlar short fibers can cause an improvement in the tensile, flexural and impact properties of HDPE/wood composites. As expected, additional surface modification of the Kevlar fiber with organosilanes and halides resulted in a further improvement on the composites mechanical properties. This effect was ascribed to the increased interfacial compatibility between the aramid fibers and HDPE, evidenced by SEM, XPS and FTIR methods. 

Liu, H., Wu, Q., Han, G., Yao, E., Kojima, Y, and Suzuki, S. (2008). Compatibilization and toughening bamboo flour-filled HDPE composites mechanical properties and morphologies. Composites Part A Applied Science andManufactur-i g 39(12), 1891-1900. 

Liu R, Cao J, Luo S, Wang X (2013) Effects of two t) pes of clay on physical and mechanical properties of poly(lactic acid)/wood flour composites at various wood flour contents. J Appl Polym Sci 127 2566-2573... 

Kord B (2011) Nanofiller reinforcement effects on the thermal, d5mamic mechanical and morphological behavior of HDPE/rice husk flour composites. BioResources 6 1351-1358 Kumar AP, Singh RP (2008) Biocomposites of cellulose reinforced starch Improvement of properties by photo-induced crosslinking. Bioresour Technol 99 8803-8809... 

Nunez, A.J., Sturm, PC., Kenny, J.M., Aranguren, M.I., Marcovich, N.E., Reboredo, M.M. Mechanical characterization of polypropylene-wood flour composites. Appl Polym Sci 2003 88(6) 1420-8. 

Stark, N.M., Matuana, D.P. Surface chemistry changes of weathered HDPE/wood-flour composites studied by XPS and ETIR spectroscopy. Polym. Degrad. Stab. 86, 1-9 (2004) Stark, N.M., Matuana, L.M. Surface chemistry and mechanical property changes of wood-flour/high-density-polyethylene composites after accelerated weathering. J. Appl. Polym. Sci. 94, 2263-2273 (2004)... 

Another possibility, which is widely used for the production of bio-nanocomposites, also with resin directty obtained from biomass, is extracting cellulose nanociystals (CNC) from other biomass source or from aspecilic cellulose. This led also to original solutions, such as the fabrication of materials including a kind of hierarchical structure, hence introducing both a macrosized reinforcement and a nanosized one. In particular, in a jute and soy flour composite, with glutaraldehyde providing suitable interface adhesion, cellulose nanowhiskers have been introduced in addition or not to nanoclay (Fig. 13.5), a procedure which provided improved thermal, mechanical and dimensional stability (Iman et al., 2013). 

Y. Hamzeh, A. Ashori, and B. Mirzaei, Effects of Waste Paper Sludge on the Physico-Mechanical Properties of High Density PolyethyleneA/Vood Flour Composites. J. of Polym and the Environ. 19 (1), 120-4 (2011). 

Another commonly employed low-cost organic filler is coconut shell flour. This can be incorporated into the moulding composition in large quantities and this results in cheaper mixes than when woodflour is used. The mouldings also have a good finish. However, coconut shell flour-filled mouldings have poor mechanical properties and hence the filler is generally used in conjunction with woodflour. 

Extrusion is a cost effective manufacturing process. Extrusion is popularly used in large scale production of food, plastics and composite materials. Most widely used thermoplastics are processed by extrusion method. Many biopolymers and their composite materials with petroleum-based polymers can also be extruded. These include pectin/starch/poly(vinyl alcohol) (Fishman et al. 2004), poly(lactic acid)/sugar beet pulp (Liu et al. 2005c), and starch/poly(hydroxyl ester ether) (Otey et al. 1980), etc. In this study, composite films of pectin, soybean flour protein and an edible synthetic hydrocolloid, poly(ethylene oxide), were extruded using a twin-screw extruder, palletized and then processed into films by compression molding process or blown film extrusion. The films were analyzed for mechanical and structural properties, as well as antimicrobial activity. 

The solid phase of bread crumb can be viewed as a composite material where amylose, amylopectin and protein form separated phases due to poor thermodynamic miscibility of the different polymers. Composites are characterized by exhibiting mechanical properties that cannot be achieved with the individual constituents alone, but are dependent on the interface between the components. A sharp interface as found between starch and protein provides strong evidence of little polymer interdiffusion and weak interfacial adhesion.14 The present results suggest that starch forms a continuous phase in bread which has also been confirmed with confocal scanning laser microscopy.15 The presence of a protein phase reduces the continuity of the starch phase and, thus, reduces the cohesion of the material as revealed by a comparison of the breaking stresses of aged flour and starch gels (data not shown).16... 

U.S. Pat. No. 4,165,302 [32] describes filled thermoplastic resin compositions comprising LDPE, polypropylene and other resins (in amonnts ranging from 95 to 50% by weight), organic fillers (snch as wood flour), and inorganic fillers (snch as fly ash or calcinm carbonate). This patent is concerned primarily with increasing the melt flow index of filled thermoplastic resin compositions rather than their mechanical properties. 

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