Panels, properties

To illustrate the correct approach, consider applications in which a material is used in sheet form, as in automotive body panels, and suppose that the service requirements are for stiffness and strength in flexure. First imagine four panels with identical dimensions that were manufactured from the four materials given in Table 3-1. Their flexural stiffnesses and strengths depend directly on the respective material s modulus and strength. All the other factors are shared in common with the other materials, there being no significantly different Poisson ratios. Thus, the relative panel properties are identical with the relative material properties illustrated in Fig. 3-3. Obviously, the metal panels will be stiffer and... 

Integral chopped fiber glass strands 1/8 In., and a hybrid of milled fiber glass and chopped strand. Six major panel properties were examined for surface... 

In general these produets are pressed to eonsolidate the mat and to cure the thermoset adhesive. Whereas in plywood pressing the main object is to achieve good contact between the veneer layers with as little inerease in density as possible, in the case of these produets the average density is one of the key variables in determining panel properties and will normally be 30-100% greater than the bulk density of the wood from which the panels are made. A major advance in all these products is the ability to control the density profile through the thiekness of the panel. 

The VDP provides a means of identifying the contribution of the press in determining panel properties, separating this effeet from other possible causes such as resin mixing and performanee, or partiele size/shape effects. It also recognises the significant effect of density on the properties of panel products. 

Among other hardwoods indigenous to the North Central United States are maple, birch and aspen. These species have little commercial value but are found in areas close to major markets. Mobay sponsored a study, conducted by the Institute of Wood Research at Michigan Technological University, to determine the effects of processing variables on isocyanate-bound flakeboard prepared from a mixture of these species and to compare resultant panel properties with those of a standard panel prepared with a commercial aqueous phenolic resin under typical processing conditions for that type of resin. 

Blends of PCTG with PC or SMA are typically formed by injection molding into business machines, appliance parts and automotive body panels. Properties are affected by injection speed, screw speed, back pressure, injection pressure, melt temperature, clamping pressure and cycle time. 

Uses Defoamer, air release agent for unsat. polyester resins (gel coats, putty, nonreinforced and reinforced applies., continuous panels) Properties YIsh. clear liq., aromatic odor insol. in water sp.gr. 0.88 dens. 7.34 Ib/gal vapor pressure 4 mm Hg (20 C) b.p. 165-185 C flash pt. (Seta CC) 43 C ref. index 1.507 38% NV Toxicology LD50 (oral, rat) 2275 mg/kg (act. ingred.) inh. of vapors may cause respiratory tract irritation, headaches, nausea, vomiting, CNS depression TSCA listed... 

Plywood has essentiahy equal stability in both panel directions and is almost as stable as the parent wood in the direction of the wood grain. Strength properties in bending are roughly proportional in each panel direction to the amount of wood in those layers closest to the surface which are parahel to the wood grain direction. Thus as the number of phes increases, these bending properties become more equalized in both panel directions. 

Then, in the early 1980s the concept of OSB was realized in the constmction and operation of large-size mills. OSB is a panel product made from wood strands and somewhat like plywood in that the strands on the two faces are oriented in the long direction of the panel and the core strands are oriented in the cross-panel direction. The use of orientation yields panels having exceUent directional properties, much like plywood, and thus an exceUent and economical stmctural sheathing material is created. 

Standard Methods of Evaluating the Properties of Wood-Base Fiber and Particle Panel Materials, ASTM D1037-93, American Society for Testing and Materials, Philadelphia, Pa.,... 

The insulating value and mechanical properties of rigid plastic foams have led to the development of several novel methods of buUding constmction. Polyurethane foam panels may be used as unit stmctural components (220) and expanded polystyrene is employed as a concrete base in thin-sheU constmction (221). 

Additives. Because of their versatility, imparted via chemical modification, the appHcations of ethyleneimine encompass the entire additive sector. The addition of PEI to PVC plastisols increases the adhesion of the coatings by selective adsorption at the substrate surface (410). PEI derivatives are also used as adhesion promoters in paper coating (411). The adducts formed from fatty alcohol epoxides and PEI are used as dispersants and emulsifiers (412). They are able to control the viscosity of dispersions, and thus faciHtate transport in pipe systems (413). Eatty acid derivatives of PEI are even able to control the viscosity of pigment dispersions (414). The high nitrogen content of PEIs has a flame-retardant effect. This property is used, in combination with phosphoms compounds, for providing wood panels (415), ceUulose (416), or polymer blends (417,418) with a flame-retardant finish. 

Automotive appHcations account for about 116,000 t of woddwide consumption aimuaHy, with appHcations for various components including headlamp assembHes, interior instmment panels, bumpers, etc. Many automotive appHcations use blends of polycarbonate with acrylonitrile—butadiene—styrene (ABS) or with poly(butylene terephthalate) (PBT) (see Acrylonitrile polymers). Both large and smaH appHances also account for large markets for polycarbonate. Consumption is about 54,000 t aimuaHy. Polycarbonate is attractive to use in light appHances, including houseware items and power tools, because of its heat resistance and good electrical properties, combined with superior impact resistance. 

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