Polypropylene flexural modulus

Effects of Strand Solid and Filament Diameter. Polypropylene Flexural Modulus, psi x 10 ... 

Table 2-4 Examples of flexural modulus of elasticity for polypropylene compounds...

Thomason JL, Vlug MA. Influence of fiber length and concentration on the properties of glass fiber-reinforced polypropylene 1. Tensile and flexural modulus. Composites Part A Applied Science and Manufacturing. 1996 27(6) 477-84. 

Figure 5.75 Effect of gas cell size on the specific flexural modulus of 6-mm-thick polypropylene structural foam. Samples were tested at 23°C with and without their outer skins. Reprinted, by permission, from P. R. Hornsby, in Two-Phase Polymer Systems, L. A. Utracki, ed., p. 115. Copyright 1991 by Carl Hanser Verlag.

Figure 5.99 Relationship of glass fiber content with (a) tensile strength and (b) flexural modulus for styrene acrylonitrile (SAN) and polypropylene (PP). Reprinted, by permission, from G. Lubin, Handbook of Fiberglass and Advanced Plastics Composites, p. 130. Copyright 1969 by Van Nostrand Reinhold.

Polypropylenes are subdivided to homopolymers and copolymers. Homopolymers are more crystalline, have a rather well-defined melting temperature at 161-165°C (322-329°F), softens at about 155°C (311°F), and have a rather narrow molecular weight distribution. Copolymers typically contain some amount of ethylene comonomer and in turn are subdivided to random and block copolymers. Their melting points are in the range of 140-155°C (284-311°F). Polypropylenes have a specific gravity (density) of 0.90-0.91 g/cm which is approximately equal to that of very low-density polyethylene and lower than that of majority of polyethylenes, particularly HDPE (0.941-0.965 g/cm ). PP homopolymers are stiffer than copolymers, with their flexural modulus of 165,000-290,000 psi and 130,000-175,000 psi, respectively. PP homopolymers, in turn, are generally stiffer compared to HDPE, which has flex modulus in the range of 125,000-... 

Flexural modulus of Nylon 6 is 100,000-464,000 psi, which is in the same range with that of PVC and ABS, and generally higher than that of HDPE and polypropylene. 

Another set of data, obtained in a wider range of wood flour content as polypropylene filler (Table 3.6), shows that flexural strength of the composite reached maximum at 40% tiller, and then decreases. Apparently, there is not enough plastic to provide good adhesion for all tiller particles. Flexural modulus, however, is increased... 

COMPOSITION OF WOOD-PLASTIC COMPOSITES MINERAL FILLERS TABLE 4.3 Effect of inorganic fillers and wood flour on flexural strength and flexural modulus of polypropylene (homopolymer) [2] ... 

On the contrary, finer talc particles increased flexural modulus of wood-flour (27.5% w/w) - filled nonoriented polypropylene (27.5% w/w) from 430,000-... 

One can see that nanoclay consistently decreases tensile and flexural strength and modulus of the polypropylene-based composite material, and only slightly (less than 10%) increases tensile and flexural modulus of the composite. 

However, adding of inorganic materials into a WPC formulation with a coupling agent can complicate an outcome. For example, addition of nanoclay to WPC (50% wood flour and 50% polypropylene) in the presence of Polybond 3200 has systematically decreased both tensile and flexural strength of the final material, for amounts of the nanoclay of 0, 2,4, and 10%. Effect of tensile and flexural modulus was more complex. The authors concluded that the nanoparticles disrupt adhesion between wood flour and the polymer matrix [24]. 

TABLE 5.11 Effect of Polybonds 3009 (HDPE-based) and Polybond 3200 (polypropylene based) on flexural strength and flexural modulus of HDPE-based composites... 

Flexural modulus of neat polypropylene is similar with that of HDPE and is in the range of 170,000-250,000 psi. Flex modulus for high-impact polypropylene is of 100,000-... 

Talc - Talc is a filler made by dry or wet grinding of mineral magnesium silicate. Talc improves stiffness, dimensional stability, flexural modulus, creep resistance, flow, surface smoothness, moisture resistance, tensile strength, and wear resistance of plastics. It also increases heat deflection temperature and decreases vapor permeability. Can be used as a film antiblock agent. Used mainly in polypropylene but also in thermoplastic and unsaturated polyesters and epoxy resins at low levels. Surface-modified grades are available. 

Table 3.1 Polypropylene NEAT and filled flexural modulus of...

Thomason, J.L. Vlug, MA. (1996). Influence of Fibre Length and Concentration on the Properties of Glass Fibre-reinforced Polypropylene 1. Tensile and Flexural Modulus. Composites Part A Applied Science and Manufacturing, Vol.27, No.6, pp. 477-484 ISSN 1359-835X... 

Figure 11.37. Flexural modulus of polypropylene plasticized with variable quantities of different plasticizers. A — dioctyl sebacate, B — isooctyl tallate, C — paraffinic oil. [Data from Ellul M D, Rubber Chem. TechnoL, 71, No.2, May/June 1998, p.244-76.[...

Improvements of some of the end-use properties are generally obtained with the simultaneous worsening of other end-use properties. For instance, rubber particles (ethylene/propylene copolymers) are usually introduced into homopropylene matrixes in order to increase the impact resistance of polypropylene resins. However, this normally causes the decrease of the flexural modulus of the polymer blend, which is often undesirable [ 1 ]. Therefore, optimum operation conditions can only be defined in terms of a tradeoff among the many end-use properties that are required for a specific final apphcation. 

Figure 3.91 Flexural modulus vs. temperature for Mitsubishi Engineering-Plastics Iupiace polypropylene ether and PS blend resins.

The specific composition of the TPO blend produced depends on the balance of flexural modulus (stiffness) and impact toughness (drop impact and notched Izod) properties needed to meet the target performance specifications. In the formulation of TPO blends, the polypropylene is used normally as the major component, i.e., as the matrix phase, to provide the needed rigidity and thermal stability, while the elastomer dispersion provides the low-temperature impact toughness. A minor amount of a mineral filler such as talc provides additional stiffness and dimensional stability to the TPO. Hence, the levels of elastomer and mineral filler modifiers are carefully adjusted to achieve the desired balance of properties in the TPO. 

Studies carried by Leao et al. [28] showed that 70% sisal fiber content in sisal polypropylene composites gave maximum tensile strength and Young s modulus, but flexural strength and flexural modulus property were found to be optimum in 60% sisal fiber, as given in Table 22.10 [28],... 

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