Composite with wood

Journal of Applied Polymer Science 88, No. 12, 20th June 2003, p.2842-50 MICROCELLULAR FOAM OF POLYMER BLENDS OF HDPE/PP AND THEIR COMPOSITES WITH WOOD FIBER Rachtanapun P SeUce S E M Matuana L M Michigan,State University... 

Rachtanapun P, Selke SEM, Matuana LM (2003) Microcellular foam of polymer blends of HDPE/PP and their composites with wood fiber. J Appl Polym Sci 88 2842-2850... 

Yano and Nakahara [15] used accessory polysaccharides to form composites with wood MFC/nanocelluloses. The disintegrated wood celluloses were mixed with starch as a binder and then hot-pressed between porous metal plates. Using a starch content of 2 wt %, the bending strength reached 310 MPa, compared to 250 MPa for unmodified fibers. Concurrently, the Young s modulus decreased from 16 to 12.5 GPa. When the starch content was 20 wt %, the bending strength decreased to 270 MPa. This indicates that added starch may act not only as a binder but also as a plasticizer. 

U.S. Pat. No. 4,820,749 (April 11, 1989). A.D. Beshay. Reinforced polymer composites with wood fibers grafted with silanes. 

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]. 

Similarly, it was shown that wood-polypropylene composites with wood (20 mesh ponderosa pine particles) content 30,40, 50,60, and 70% lost weight under action of brown-rot fungus, Gloeophyllum trabeum, for 12 weeks in the following order 0.2,... 

Table 1. Composition and code of the wood/polymer composites (percentage is in weight). The star ( ) denotes a composite with Wood/PP and 5% wt MAPP.

In this work, the thermal stability, the process of crystallization and melting of PP in its composites with wood (red pine) are studied by SEM analysis and differential scanning calorimetry, respectively, as a function of the wood content and coupling agent. 

The fluidity of plastic is chosen on the basis of the molding method (molded machine and type of mold) and composition (content of wood flour). In extrusion molding, low fluidity has a bad influence on the productivity, and high fluidity induces the problem of stability of forming. Furthermore, depending on the fluidity of the plastic and the shape of wood flour, the orientation of wood flour must be also taken into account. In the case of wood/oleflnic resin composite with wood flour content of 50%, the plastic with fluidity (melt flow rate, MFR) of O.l-lOg/lOmin is general used. 

Composites with wood material and polymer can be prepared in two ways. In the first, the wood fiber/flour is a reinforcing agent or a filler in a continuous thermoplastic matrix. In the second, the thermoplastic is a binder to the majority wood component. Only the first approach is discussed hereafter since a continuous thermoplastic matrix determines the processability of the composite material and is the necessary condition for processing WPC with conventional thermoplastic processing techniques, whilst certain adaptation of the equipment and operation may be required. 

Figure 2. Polyamide 6 (upper left) and polyamide 6/TC 2500 wood fiber composites with wood fiber content increasing to the right. The top row was extrusion and compression molded and the bottom row was ground and injection molded. 

Although the use of simple diluents and adulterants almost certainly predates recorded history, the use of fillers to modify the properties of a composition can be traced as far back as eady Roman times, when artisans used ground marble in lime plaster, frescoes, and po22olanic mortar. The use of fillers in paper and paper coatings made its appearance in the mid-nineteenth century. Functional fillers, which introduce new properties into a composition rather than modify pre-existing properties, were commercially developed eady in the twentieth century when Goodrich added carbon black to mbber and Baekeland formulated phenol— formaldehyde plastics with wood dour. 

Wood (qv) is arguably the oldest building material used by humans to constmct their dweUings. It is a natural product obtained from trees, used in both stmctural and decorative appHcations. The chemical composition of wood is largely cellulose (qv) and lignin (qv). Today there are a variety of composite or reconstituted wood products, such as plywood, particle board, wood fiber boards, and laminated stmctural beams, where small pieces of wood or wood fiber are combined with adhesives to make larger sheets or boards (see Laminates). 

The mechanical properties of composites reinforced with wood fibers and PVC or PS as resin can be improved by an isocyanate treatment of those cellulose fibers [41,50] or the polymer matrix [50]. Polymethylene-polyphenyl-isocianate (PMPPIC) in pure state or solution in plasticizer can be used. PMPPIC is chemically linked to the cellulose matrix through strong covalent bonds (Fig. 8). 

This yields a value for the total OH content of approximately 14.8 x 10 moles per gram of dry wood mass. This value is relatively insensitive to the polymeric composition, with... 

Mahlberg etal. (2001) studied the effect of acetylation of wood fibres (20 % WPG) upon the mechanical properties of wood fibre PP fibre composites, with and without the addition of a novalak PF. Acetylation resulted in significant improvements in MOR, MOE and IBS in a composite containing 20 % by weight of PP fibre. With a combination of PF and PP (both 10 % by weight) and acetylated wood fibre, MOR was unchanged, MOE decreased and only IBS showed a significant improvement. Acetylation also contributed to a better dispersion of the wood fibres in the PP matrix. 

The use of enzymatic systems for surface activation of wood particles to form binderless composites has been the subject of study for over 20 years. Enzyme-catalysed bonding of wood can be achieved either by activation of lignin, which is mixed with wood particles, or by surface activation of the wood particles directly (Grdnqvist etal., 2003). 

Chtourou, H., Riedl, B. and Ait-Kadi, A. (1992). Reinforcement of recycled polyolefins with wood fibres. Journal of Reinforced Plastic and Composites, 11, 372-394. 

Saka, S., Sasaki, M. and Tanahashi, M. (1992). Wood-inorganic composites prepared by the sol-gel process I. Wood-inorganic composites with porous structure. Mokuzai Gakkaishi, 38(11), 1043-1049. 

Synthetic wood or wood-plastic composites (WPC) made from rigid PVC heavily filled with wood flour, extruded in wood-like profiles that can be sawn, nailed and screwed just like natural wood. .. 

Hybrids combine plastics or composites with other materials such as metal, wood, etc. Plastics filled with talc or other powders are not taken into account in this chapter. 

For dehydration, place the platinum (nickel) crucible with the prepared salt ( 5 g) into a test tube with a standard ground-glass joint (Fig. 63). Preliminarily weigh the crucible and the salt with an accuracy up to 0.01 g. Connect the test tube to a vacuum system. Evacuate it (10- mmHg) first at room temperature during 10-20 min, and then at 150 °C on an oil bath or a bath with Wood s alloy. Dehydrate the substance up to a constant mass. Calculate the composition of the product according to the change in its mass. 

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