HIGH HEAT TESTING UNDER LOAD
Specimens were cured 3 Hours at 25˚C plus 3 Hours At 135˚C
Flexural strength is also known as modulus of rupture, bend strength, or fracture strength. Flexural strength is measured in terms of stress, and thus is expressed in pascal (Pa) in the SI system. The value represents the highest stress experienced within the material at its moment of rupture. In a bending test, the highest stress is reached on the surface of the sample.
For a rectangular sample under a load in a 3 point bend setup:
F is the load (force) at the fracture point
L is the length of the support span
b is width
d is thickness
The general physical property of a plastic polymer is that it is directly correlated with temperature it is exposed to. By exposing it to varying degree of heat a graph can be plotted and this will demonstrate the relationship such as heat resistance of a polymer to temperature. But in no clear manner that the Shore Hardness of a polymer will reveal other mechanical properties such as Heat Distortion, Transition of glass or Tg and other mechanical properties.
The graph presented above serves as a guide on how MAX HTE performs when it is heated to varying temperatures. A 6 inch by 6 inch 1/2 inch thick specimen cured per the schedule above was exposed to measured elevated temperature and the Shore Hardness was measured which provides an excellent test for the heat resistance. A similar performance trend in compression, tensile and tensile shear and other mechanical test was observed.
Durometer Hardness is used to determine the relative hardness or softness of materials, usually plastic or rubber. The test measures the penetration of a specified indenter into the material under specified conditions of force and time.
The hardness value is often used to identify or specify a particular performance of a plastic as quality control measure or performance latitude.
The hardness numbers are derived from a scale used predominantly in polymer plastics; these are Shore A and Shore D hardness.
A 6 inch by 6 inch by ¼ inch cured sample of the MAX HTE was exposed to ascending temperature condition and the surface hardness was tested using a both Type A and Type D Shore Hardness Durometer. Shore Hardness determines the resistance of a plastic substrates’ resistance to surface deformation from a constant load.
The Shore Hardness testing was performed in compliance with ASTM D 2240
This graph demonstrates the heat resistance of the surface hardness of MAX HTE in relation to exposure temperature. Other heat exposure related mechanical test was performed to determine MAX HTE’S heat resistance properties and yielded identical trend line as this graph demonstrates.
The A scale is used for softer and flexible materials such as rubber or polymers that can be flexed without rupturing.
The D scale being used for harder materials such as plastic sheeting, plastic hard hats or plastic interior car trims.
The carbon fiber laminate was allowed to cure for 4 hours under vacuum pressure and post cured under solar heat for and additional post heat cure.