“Stiffness” refers to the amount of force required for a unit deformation of the object; “Flexibility” refers to the amount of deformation of an object under a unit force. The larger the “stiffness” is, the less deformation is likely to occur; the greater the “flexibility”, the more prone to deformation. The material with good toughness is soft, and the tensile elongation at break and impact strength are larger, while the hardness, tensile strength and tensile elastic modulus are smaller.
As can be seen from the above description, stiffness and toughness are opposites, but for modified plastics they are interdependent. For example, when fiberglass reinforced plastics become more rigid, both tensile strength and impact strength may increase.
How to improve plastic toughness?
It is found that increasing the toughness of matrix resin can improve the toughening effect of toughened plastics.
There are many ways of toughening, such as increasing the molecular weight of the matrix resin to narrow the molecular weight distribution, or controlling the crystallization, crystallinity, crystal size and crystal shape to improve high toughness.
How to distinguish plastic commonly used toughening agent?
• Rubber elastomer toughened
EPR (binary ethylene-propylene), EPDM (EPDM), butadiene rubber (BR), natural rubber (NR), isobutene rubber (IBR), nitrile rubber (NBR), etc. Suitable for all plastic resin toughening modification;
• Thermoplastic elastomers are toughened
SBS, SEBS, POE, TPO, TPV, etc. For polyolefin or non-polar resin toughening, for polyester, polyamide and other polymers containing polar functional groups toughening need to add compatibilizers;
• Toughened core-shell copolymer and reactive terpolymer
ACR (acrylate), MBS (methyl acrylate-butadiene-styrene copolymer), PTW (ethylene-butyl acrylate-glycidyl methacrylate copolymer), E-MA-GMA (ethylene-methyl acrylate-glycidyl methacrylate copolymer), etc. Used for engineering plastics and high temperature resistant polymer alloy toughening;
• Toughened by blending high tenacity plastics
PP/PA, PP/ABS, PA/ABS, HIPS/PPO, PPS/PA, PC/ABS, PC/PBT, etc. Polymer alloy technology is an important way to preparehigh toughness engineering plastics.
• Other ways to toughen
Toughening of nano-particles (such as nano-cacO3), toughening of sarin resin (Dupont metal ionomer), etc.