Elongation at-break

Elongation at break is the strain at which the polymer breaks when tested in tension at a controlled temperature (i.e., the tensile elongation at specimen break). 

An increasing number of applications are being developed for thermoplastics in which a fabricated article is subjected to a prolonged continuous stress. Typical examples are pipes, crates, cold-water tanks, and engine cooling fans. Under such conditions of constant stress, materials exhibit (to varying extents) continuous deformation with increasing time. This phenomenon is called creep. 

The general form of this creep curve can be described as follows. Upon application of the load, an instantaneous elastic deformation occurs (0-A). This is followed by an increase in deformation with time as represented by the portion of 

Identification of Reinforced Polymers with Outstanding Tensile Strength and Flexural Modulus 

Epoxies 60-80 3-3.5 4-8 N/A 0.5 Tensile strength, flexural modulus. Poor surface finish, high cost. v  

The change in elongation curves, with very few exceptions, showed a downward trend with time. This was also the case for natural ageing. Hence, the pattern of change was quite consistent. However, there were many instances where the curves at different temperatures crossed so that there was inconsistency in terms of the trend with temperature. 

In the stretching process of external forces that are perpendicular to the section, equal and opposite in direction, the 

This definition is widely used in engineering and referred to as relative elongation and abbreviated as elongation. 

The elongation of a sample at break is called elongation at break, and defined as the percentage of tensile strain at break  

Hardness is an indicator of a material surface to resist mechanical stress. Hardness is related to tensile strength and the elastic modulus of a material, and is therefore sometimes used as an approximate estimation of tensile strength and the elastic modulus. 

Hardness can be measured by many methods, including dynamic loading and static loading. The former applies an elastic rebound method and impact force to press in the steel ball. The latter uses a hard material with a certain shape as the head and presses the head into the sample by gradual loading. 

The incorporation at 25-50% of glass fibre into polymers usually produces a dramatic deterioration of the percentage of elongation at break (see Table 2.11). 

Polymer Unreinforced polymer Glass fibre reinforced polymer  

Carbon fibre causes a decrease in elongation at break point from 110 to 2.7% for PC and from 65 to 1 % for polyacetal. The addition of minerals or silica to epoxy resins 

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Specimens used in tests were sections of cables with PVC outer coating. PVC was plasticized with DOF softener. The materials considered were exposed to the radiation and thermal aging. The samples have been irradiated at room temperature by hard gamma rays with 10 rad/sec dose power. A number of samples had been heated for long different times at 90°C. Besides a special specimens were cut out from outer coating for test on tensile machine like "Instron". The total doses of irradiation, times of heating and elongations at break obtained with "Instron" are listed in Table 1. 

Fiber Tenacity, N /tex Initial modulus, N/tex Elongation at break, %... 

The TPX experimental product of Mitsubishi Petrochemical Ind. (221) is an amorphous, transparent polyolefin with very low water absorption (0.01%) and a glass-transition temperature comparable to that of BPA-PC (ca 150°C). Birefringence (<20 nm/mm), flexural modulus, and elongation at break are on the same level as PMMA (221). The vacuum time, the time in minutes to reach a pressure of 0.13 mPa (10 torr), is similarly short like that of cychc polyolefins. Typical values of TPX are fisted in Table 11. A commercial application of TPX is not known as of this writing. 

Content of Ot-Olefin. An increase in the a-olefin content of a copolymer results in a decrease of both crystallinity and density, accompanied by a significant reduction of the polymer mechanical modulus (stiffness). Eor example, the modulus values of ethylene—1-butene copolymers with a nonuniform compositional distribution decrease as shown in Table 2 (6). A similar dependence exists for ethylene—1-octene copolymers with uniform branching distribution (7), even though all such materials are, in general, much more elastic (see Table 2). An increase in the a-olefin content in the copolymers also results in a decrease of their tensile strength but a small increase in the elongation at break (8). These two dependencies, however, are not as pronounced as that for the resin modulus. 

Polyolefins. Interest has been shown in the plasticization of polyolefins (5) but plasticizer use generally results in a reduction of physical properties (12), and compatibiHty can be achieved only up to 2 wt %. Most polyolefins give adequate physical properties without plasticization. There has been use of plasticizers with polypropylene to improve its elongation at break (7) although the addition of plasticizer can lower T, room temperature strength, and flow temperature. This can be overcome by simultaneous plasticization (ca 15 wt % level) and cross-linking. Plasticizers used include DOA. 

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