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Some important test for plastic--part 3
- Sep 01, 2017 -

Pendulum Impact test (include charpy impact test and izod impact test)


necessary test equipment: Charpy impact testing machine/Izod impact testing machine

 

Definition: The pendulum strikes the middle of the Charpy beam specimen, causing the specimen to be impacted and broken. The impact energy consumed by the unit area or unit width when the specimen is broken is the impact strength.

 

Purpose: Impact toughness is to describe the toughness of polymer materials under high-speed impact, or anti-fracture ability. In general, impact toughness includes two aspects: the impact of the deformation after the ability and carry the fracture capacity, the former is generally expressed with the elongation at break, while the latter is generally used to express the impact strength.

 

Impact strength calculation formula: E = A / bd

A: that the power consumed when the impulse; b / d, respectively, said the impact of the width and thickness of the site; E is the impact strength.

 

The power consumed by the thrust sample is generally divided into the following aspects:

a) Cracks the specimen to crack

b) to break some of the cracks through the entire sample

c) deform the polymer near the crack

d) Fight the broken sample fragment

e) a small amount to overcome the air resistance and friction between mechanical parts

Note: In general, the greater the impact energy absorbed before it is damaged, the greater the elongation at break, the better the impact toughness of the material.

 

Heat deflection temperature

necessary test equipment:HDT&vicat softening point temperature tester

Definition:The polymer material or polymer to impose a certain load to a certain rate of temperature, when the specified deformation to achieve the corresponding temperature.

Test principle: plastic sample on the span of 100mm on the bearing, put it in a suitable liquid heat transfer medium, and at the midpoint of the two seats, the application of a specific static bending load, In the constant temperature conditions, the specimen bending deformation to a specified value.

Test purpose: in the glass or crystalline state of the polymer, with the temperature increases, atomic and molecular motion energy, under external force due to its directional movement caused by the ability to deformation, that is, the ability of materials to resist external forces - The modulus decreases with increasing temperature, and as the temperature increases, the deformation of the plastic increases under a fixed load.

Influencing factors:

1) Test equipment (reading error, sample placement)

2) Method and size of sample preparation

3) heat transfer medium

 

 

Vicat softening temperature test

necessary test equipment:HDT&vicat softening point temperature tester

Vicat tester

Test principle: the plastic sample placed in the liquid heat transfer medium, in a certain load and a certain constant temperature conditions, the sample was 1 square mm pressure needle into the pressure of 1mm.

 

Significance: Vicat softening temperature is one of the indicators that evaluates the heat resistance of the material and reflects the physical and mechanical properties of the product under heat conditions. The Vicat softening temperature of the material can not be used directly to evaluate the actual use temperature of the material, but it can be used to guide the quality control of the material. The higher the softening temperature of Vicat, the better the dimensional stability of the material when heated, the smaller the thermal deformation, that is, the better the heat resistance deformation, the higher the rigidity and the higher the modulus.