【China plastic machinery network industry trends 】"Rigidity" refers to the object unit deformation occurs to the size of the force; "Flexibility", refers to the object of deformation under unit force size.
As you can see, "rigidity" the larger the object, the less prone to deformation (performance in elongation small); "Flexibility", the greater the deformation of object, the more likely to happen in elongation larger (). An ideal state, the object of stiffness tend to infinity force effect of the small deformation (or object to negligible levels), we will call the object of rigid body. In the mechanical analysis, can not consider its deformation. Therefore, rigid reflect the degree of deformation object is one attribute. Physical table of toughness of the material is soft, tensile elongation at break, impact strength; Hardness, tensile strength and tensile modulus of elasticity is relatively small. Rigid material and its hardness, tensile strength; Elongation at break and impact strength could be lower; Tensile modulus of elasticity is larger. Bending strength of reaction materials size rigidity, bending strength is big rigidity, toughness big conversely. in
ASTMD790 bending performance standard test method, the test method is suitable for rigid material is suitable for semi-rigid materials. Did not say that it is suitable for ductile material, so the toughness elastomer is not to test the bending strength.
Research and development of modified plastics "rigidity" and "flexibility" as important indicators
The above said toughness and rigidity and testing of mechanical performance relationship is relative. There may be an accident. After using glass fiber reinforced plastic, for example, its larger rigidity, but may also appear the possibility of tensile strength and impact strength are increased. In shock, shock loads, the material can absorb large energy produce certain deformation and destruction of nature is called the toughness and impact toughness. Construction steel (mild steel), is a typical ductile material such as wood, plastic.
Roads, Bridges, crane beam and the structure of the seismic requirements are want to consider the toughness of the material. Rigidity and brittleness is generally together. Brittleness is when the external force reaches a certain limit, the material without aura of sudden failure, no obvious plastic deformation and destruction of nature. The characteristics of the brittle material mechanical properties is greater than the tensile strength, compressive strength and destroyed the ultimate strain of little value. Brick, stone, ceramic, glass, concrete, such as cast iron is a brittle material. Compared with the ductile materials, their effect on resistance to impact load and vibration under is very bad.
As engineering plastics, we hope that it also has good toughness and rigidity. To improve the toughness of the material, also should try to improve the rigidity. General to join elastomer can increase the toughness, adding inorganic filler can increase rigidity. The most effective way is to enhanced elastomer toughening and packing together. Shock resistance is poor performance defects of some important plastic industry.
Such as PVC, PS, PP, etc., especially at low temperature due to the low shock resistance and make its application is restricted. In thermoplastic, however, by adding the impact modifier could greatly improve the shock resistance of them. A wide variety of impact modifier, commonly used have ACR - acrylate resin, MBS - - butadiene - styrene copolymer of methyl methacrylate, CPE, chlorinated polyethylene, ABS, EVA, EPT - three yuan 3-20, etc. From the perspective of the modification effect of plastics, ACR is one of the best comprehensive performance category, transparent products is important to MBS impact modifier, the global impact modifier occupies an important position in the market.
Article links: China plastic machinery network at http://www.86pla.com/news/Detail/32171.html
