Laminates flexural modulus

Resistance to moisture Flexural strength Flexural modulus Tensile strength Postforming laminate only Postformability Blister resistance Melamine-faced chipboard only Resistance to wet heat Surface soundness Composite boards only ... 

For the three-point bending test of the sixth plys laminate panels, the flexural strength of the PTFE / FP composite was about 2.9 times higher than that of the PTFE composite. Moreover, the flexural modulus of the PTFE / FP... 

Table III shows the flexural properties of RX-PTFE composite with an EB dose of 500 kGy and SX-PTFE composite (fluorinated-pitch 1.8 wt% additive) with an EB dose of 500 kGy. For the three-point bending test of the sixth plys laminate panels, the flexural strength of SX-PTFE composite was about 1.1 times higher than that of the RX-PTFE composite. The flexural modulus of SX-PTFE composite was about 1.3 times higher than that of RX-PTFE composite. It was found that the flexural properties of SX-PTFE were improved, compared with RX-PTFE composite.

Table 111. The flexural strength and flexural modulus of the carbon fiber-reinforced RX-PTFE (RX-PTFE composite) and the carbon fiber-reinforced SX-PTFE (SX-PTFE composite). Volume of carbon fiber was 54.3 %, Sixth plys laminated panel.

Answer by Author Polymers of chlorotrifluoroethylene have been evaluated. They result in laminates with considerably higher values for flexural modulus at room temperature, and with slightly higher values for compressive modulus at — 320 F. 

Boron fibers have also been used in the form of epoxy prepreg tapes in which the filaments are carefully aligned and tensioned to provide a one-fllament-thick tape. Generally, these tapes are composed of 65-70 percent filaments in the epoxy resin matrix. The longitudinal flexural modulus of boron-epoxy laminates made in this way is about 27 X 10 psi, and the flexural strength is 280,000 psi. Boron fibers have also been applied to reinforce epoxy novolacs, phenolics, and polyimides in laminate construction. 

Janick and Kroliskowski [40] investigated the effect of Charpy notched impact strength on the flexural modulus of polyethylene and polyethylene terephthalate. Polymers with good flexural modulus include polydiallylisophthalate (11.3 GPa), phenol-formaldehyde (6.5 GPa), alkyd resins (8.6 GPa), and polyphenylene sulfide (13.8 GPa), as well as glass-filled polyester laminate (16 GPa) epoxy resins (3-3.5 GPa), sUica-fiUed epoxies (15 GPa), and acetals containing 30% carbon fiber (17.2 GPa). 

A preaccelerated, summer grade, laminating resin with excellent wettability, suitable for the fabrication of large structures, tanks and boats. Can also be used for the reinforced backing to acrylic baths. More economical than the general purpose PGL 322 PLT 232, but in comparison to those systems, also able to provide laminates of greater tensile flexural strength, as well as flexural modulus. 

Figure 4.6 Effect of glass content on tensile modulus and flexural modulus for a variety of glass-reinforced laminates (Arvesen).

Figure 4.15 (a) Flexural modulus, and (b) flexural strength of CSM laminates with various resins (Creux). 

It has been shown that recycled FR-4 epoxy laminates are advantageous fillers for UPRs [58]. Moreover, caldiun carbonate and copper were used as additional fillers. The fillers affected the curing rate, decreased the flexural strength and increased the flexural modulus. The shredded laminates were used in the amount of 100 phr. 

Carbon-Fiber Composites. Cured laminates of phenoHc resins and carbon-fiber reinforcement provide superior flammabiHty resistance and thermal resistance compared to unsaturated polyester and epoxy. Table 15 shows the dependence of flexural strength and modulus on phenoHc—carbon-fiber composites at 30—40% phenoHc resin (91). These composites also exhibit long-term elevated temperature stabiHty up to 230°C. 

Flexure testing (ASTM D790-76) was performed on 12 ply unidirectional laminates with the fibers oriented at 0° and 90° to the support span. Specimens were 25 mm wide, nominally 100 mm long and tested at a span-to-thickness ratio of 32 1. The specimens were three point loaded and the rate of strain in the outer fibers was kept constant at 0.01 (mm/min) per min. Load vs. deflection curves were recorded for determination of the modulus and yield properties. 

Schulte [46,47] has demonstrated how different organic solvents, such as hydraulic fluid encountered in the aerospace stmctures, lead to a reduction in the secant modulus of 45° glass fibre laminate under flexural fatigue and the number of cycles to failure. The matrix in this case was a polyether imide (PEI) which is plasticised by ingress of the fluid. A reduction in the matrix modulus means that the shear strength of the matrix will also be reduced with the consequence that the failure mechanism in flexure will change from matrix-fracture to delamination. 

Thermophvsical Profile. Typical 181 B-glass (A-llOO finish) PABM laminate mechanicals are shovm in T le I. Room temperature flexural strength and modulus are 70,000 psi and 4,000,000 psi, respectively. These laminates retain 709 and 80 i, respectively of their room temperature flexural strength and modulus at 480°F. 

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