Mechanical properties flexural modulus

Soykeabkaew, Supaphol, andRujiravanit (2004) produced starch-based composite foams by baking starch batters incorporating either jute or flax fibers. Mechanical properties (flexural strength and flexural modulus of elasticity) were markedly improved with the addition of 5-10% of the fibers. The authors attributed the results to the strong interaction between the fibers and the starch matrix. 

Excellent mechanical properties with very high values for tensile strength, flexural strength and modulus in the flow direction. This applies to unfilled materials and may be further enhanced by incorporation of fibrous fillers. Quoted data for these properties are in the following ranges ... 

The main reasons for this lie in feasibility. Conducting fillers are rather expensive and their use increases the cost of an article. Besides, filled polymers have worse physical-mechanical properties, especially impact strength and flexural modulus. The use of fillers is also detrimental to the articles appearance and calls for additional treatment. The continuous development of electronics has also contributed to a loss of interest to conducting composites as screening materials the improvement of components and circuits of devices made it possible to reduce currents consumed and, thereby, noise level a so called can method is practised on a wide scale in order to cover the most sensitive or noisy sections of a circuit with metal housings [14]. 

Amorphous polyarylates are light-amber transparent materials which exhibit mechanical properties comparable to that of unfilled PET in terms of tensile or flexural strength and modulus (Table 2.13) but are notably superior in terms of heat resistance (HDT = 174°C vs. 85°C for PET) and impact strength. 

Alternatively, NIR spectroscopy has been applied to relate NIR data to mechanical properties [4], A multivariate data analysis was performed on a series of commercial ethene copolymers with 1-butene and 1-octene. For the density correlation, a coefficient of determination better than 99% was obtained, whereas this was 97.7% for the flexural modulus, and only 85% for the tensile strength. 

PBT will absorb very little water (0.08 %), and its mechanical properties are not affected in the short term. Polyamides, on the other hand, may absorb up to 12% of water. In nylon resins, the water acts as a plasticizer it lowers the Tg, decreases the flexural modulus, and may cause part growth. Based on these criteria alone, polyesters are often a better choice than nylons for many applications (less variation of properties). 

A number of mechanical properties have been studied that may affect the clinical success of dental composite restorative materials. Among these are diametral tensile strength (DTS), flexural strength, fracture toughness, elastic modulus, hardness, and fatigue resistance. The mechanical properties should approximate those of tooth structure [183], but correlation of clinical success to any of these properties is limited. 

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