Flexural loading properties

Table 8.1 Flexural (three-pt loading) properties of BMAS matrix/SiC/BN/Nicalon fiber composites24...

The PPO-PA blends shown a mold shrinkage of 0.001 in./in. The molding pressure in 15 X10 Ibf/in. (103 MPa) and the processing temperature 260°C. The heat-deflection temperature of the molded specimen under flexural load of264 Ibf/in. is typically 190°C and the maximum resistance to continuous heat is 175°C. The coefficient of linear expansion is 10 cm/cm °C. The mechanical properties of the PPO-PA blends are shown in Table 4.29. 

Due to creep experiments particularly at tensile loading are much easier to handle than stress relaxation measurements long-term relaxation data of polymers are rarely available in Uterature and databases, therefore. Compared to tensile loading three- or four-point flexural loading to determine the long-term creep and relaxation properties is often applied especially in case of thermosets, brittle thermoplastic and... 

ASTM D638-95, Standard Test Method for Tensile Properties of Plastics (Philadelphia, 1996) ASTM D648-82, Deflection Temperature of Plastics Under Flexural Load (Philadelphia, 1988) ASTM D671-93, Flexural Fatigue of Plastics by Constant Amplitude of Force (Philadelphia, 1993)... 

Flammability of interior materials for road vehicles, tractors, machinery for agriculture tmd forestiy Tknsile properties-, Poisson s ratio Deflection temperature under flexural load Compressive properties of rigid plastics Determination of coefficient of linear thermtJ exptmsion (CLTE)... 

In an attempt to maximize flexural properties, PP/VB composites were fabricated with the reinforcing preform layers selectively placed near the composite surfaces where the greatest tension / compression occurs during flexural loading. During the composite fabrication process, PP sheets of varied thickness were used in order to situate two preform layers just inside both composite surfaces. The tensile and flexural mechanical properties for a -<10 VB wt.% composite with such uneven fabric distribution are provided in Table II along with the properties for its... 

While tensile and torsion bars are the usual methods to determine engineering properties, other methods can be used to determine material properties such as prismatic beams under bending or flexure loads similar to... 

Service life for a particular plastic can be defined differently according to its area of application and the particular property that is critical for its serviceability, as well as for additional requirements (e.g., continuous mechanical load, cyclic flexural load). Important is that the property investigated by the aging test corresponds directly with the property required by the application, or is clearly related to it. Moreover, the property value that indicates the end of serviceability has to be clearly defined instead of a numerical value, this can also be an external condition provided by a reference sample. There are several ways to deduce service life in applications from the test results ... 

These differences suggest that the flexural test which is commonly used to characterize the properties of FRC may be difficult to interpret in an attempt to resolve parameters of basic physical significance, such as those associated with first crack stress and multiple cracking. However, since in practice most FRC composites are subjected to flexural loading, the flexural test is probably the most suitable one to use. 

Polycarbonates with superior notched impact strength, made by reacting bisphenol A, bis-phenol S and phosgene, were introduced in 1980 (Merlon T). These copolymers have a better impact strength at low temperatures than conventional polycarbonate, with little or no sacrifice in transparency. These co-carbonate polymers are also less notch sensitive and, unlike for the standard bis-phenol A polymer, the notched impact strength is almost independent of specimen thickness. Impact resistance increases with increase in the bis-phenol S component in the polymer feed. Whilst tensile and flexural properties are similar to those of the bis-phenol A polycarbonate, the polyco-carbonates have a slightly lower deflection temperature under load of about 126°C at 1.81 MPa loading. 

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