Reinforcement tensile properties

Bisphenol A diglycidyl ether [1675-54-3] reacts readily with methacrylic acid [71-49-4] in the presence of benzyl dimethyl amine catalyst to produce bisphenol epoxy dimethacrylate resins known commercially as vinyl esters. The resins display beneficial tensile properties that provide enhanced stmctural performance, especially in filament-wound glass-reinforced composites. The resins can be modified extensively to alter properties by extending the diepoxide with bisphenol A, phenol novolak, or carboxyl-terrninated mbbers. 

In the pulp and paper industry, anionic and cationic acrylamide polymers are used as chemical additives or processing aids. The positive effect is achieved due to a fuller retention of the filler (basically kaoline) in the paper pulp, so that the structure of the paper sheet surface layer improves. Copolymers of acrylamide with vi-nylamine not only attach better qualities to the surface layer of.paper, they also add to the tensile properties of paper in the wet state. Paper reinforcement with anionic polymers is due to the formation of complexes between the polymer additive and ions of Cr and Cu incorporated in the paper pulp. The direct effect of acrylamide polymers on strength increases and improved surface properties of paper sheets is accompanied by a fuller extraction of metallic ions (iron and cobalt, in addition to those mentioned above), which improves effluent water quality. 

The tensile properties of the extruded blends and composites are presented in Table 2. Compared to the neat PP, a clear reinforcement was achieved after twin-screw blending. The reinforcing effect was even more pronounced with the higher take-up speed (H), evidently due to the extremely fibrillar morphology, as seen in Fig. 3. 

Table 4 also reports dependence of the mechanical tensile properties of the samples on the processing conditions. The highest tensile properties of sample 1, injection molded with a lower melt temperature and a lower volume flux, are attributed to the highest degree of fibrillation of the TLCP fibers, as shown in Fig. 12, by so-called in situ reinforcement. 

In the middle of the last century, the tensile properties of concrete were improved by the introduction of steel to reinforce the concrete. This practice has developed since then to such an extent that reinforced concrete is now one of the major structural materials used in construction. In general it has proved to be a good durable material with some of the structures erected at the turn of the century still providing satisfactory service in the late 1970s. 

ISO 527-4, Plastics - Determination of tensile properties - Part 4 Test conditions for isotropic and orthotropic fibre-reinforced plastic composites, 1997. 

Kelly, A. and Tyson, W. R., Tensile properties of fiber reinforced metals copper tungsten and copper/molybdenum,. /. Mech. Phys. Solids, 13, 329 (1965). 

Fu SY, Lauke B, Mader E, Yue CY, Hu X. Tensile properties of short-glass-fiber- and short-carbon-fiber-reinforced polypropylene composites. Composites Part A Applied Science and Manufacturing. 2000 31(10) 1117-25. 

ISO 527-4 1997 Plastics - Determination of tensile properties - Part 4 Test conditions for isotropic and orthotropic fibre-reinforced plastic composites ISO 527-5 1997 Plastics - Determination of tensile properties - Part 5 Test conditions for unidirectional fibre-reinforced plastic composites ISO 1798 1997 Flexible cellular polymeric materials - Determination of tensile strength and elongation at break... 

Figure 5.133 Comparison of tensile properties of fiber-reinforced bone cement (PMMA) and human compact bone. Reprinted, by permission, from Concise Encyclopedia of Composite Materials, A. Kelly, ed., p. 270, revised edition. Copyright 1994 by Elsevier Science Publishers, Ltd.

An important feature of filled elastomers is the stress softening whereby an elastomer exhibits lower tensile properties at extensions less than those previously applied. As a result of this effect, a hysteresis loop on the stress-strain curve is observed. This effect is irreversible it is not connected with relaxation processes but the internal structure changes during stress softening. The reinforcement results from the polymer-filler interaction which include both physical and chemical bonds. Thus, deforma-tional properties and strength of filled rubbers are closely connected with the polymer-particle interactions and the ability of these bonds to become reformed under stress. 

Figure 1 5.5 Reinforced plastics, steel, and aluminum tensile properties compared (courtesy of Plastics FALLO)...

This moldable material primarily consists of TS polyester resin, glass fiber reinforcement, and filler. Additional ingredients, such as low-profile additives, cure initiators, thickeners, and mold-release agents are used to enhance the performance or processing of the material. As with any material, such as metallics and plastics, SMC can be formulated in-house or by compounders to meet performance requirements of a particular application such as tensile properties or Class A surface finish. Varying the type and percentage of the composition will result in variations in mechanical properties and processability. 

Crucially, structure of CNTs and polymers plays a key role on mechanical properties and load-transfer of nanocomposites. Efficient load-transfer is only possible when adequate interfacial bonding strength is available. Interfacial failure may compromise the reinforcement effect and then the full potential of CNTs may not be realized (11). Therefore, it is of great importance to understand the effect of molecular structure, interfacial structure and morphology characteristics on the tensile properties of nanocomposite materials. 

---