GB/T 1634.2-2019 Active

This part of GB/T 1634 specifies three methods for determining the load deformation temperature of plastics (including filled plastics and plastics reinforced with fibers less than 7.5 mm in length) and hard rubber using different constant bending stress values. -- Method A using a bending stress of 1.80 MPa; -- Method B using a bending stress of 0.45 MPa; -- Method C using a bending stress of 8.00 MPa. The standard deflection Δs used to determine the load deformation temperature corresponds to the bending strain increment Δεf specified in this part. The initial bending strain of the specimen under load at room temperature is neither described nor measured in this part. The ratio of the bending strain difference to the initial bending strain depends on the room temperature elastic modulus of the tested material. Therefore, this method is only suitable for comparing the load deformation temperatures of materials with similar elastic properties at room temperature.