Mechanism of action of toughening agents
1.Elastomer toughening mechanism.
Silver grain-shear band theory:
Elastomer particles (0.1-1μm) act as stress concentration points to induce silvering
Simultaneously promotes shear yielding of the matrix (energy absorption 5-10 times higher than silver grain).
Typical system: HIPS (polystyrene/butadiene rubber)
Cavitation mechanism:
Formation of micro cavities (50-200 nm) in the rubber phase under stress.
Induces plastic deformation of the substrate (e.g. PP/EPDM systems).
Volume expansion by cavitation up to 300% of the original volume
2. Rigid particle toughening
Nano CaCO₃ toughening:
Particle size <100nm, notched impact strength increase 3-5 times
Optimal additive amount 5-15wt% (surface needs silane coupling agent treatment)
Core-shell structure particles:
PMMA-g-PB (acrylate shell/butadiene core)
PVC notched impact strength up to 80kJ/m².
3. Multiple mechanism synergy
POE-g-MAH toughens PA6:
At 0.8-1.2% maleic anhydride grafting ratio
Impact strength increased from 6kJ/m² to 45kJ/m².
While maintaining tensile strength >50MPa
Key Application Areas
1.Engineering plastics modification
Car bumper (PP modification):
Formulation: PP 70% + POE 15% + Talc 15%.
Performance: Notched impact >45kJ/m² (-30°C)
Electrical and electronic housings (PC/ABS):
MBS 8-12% added
Falling ball impact test: 1kg steel ball 1m height without rupture
2.Special materials
Super tough nylon (PA66):
EPDM-g-MAH 10-15%
Cantilever beam impact >90kJ/m²
For rail components
Transparent toughened PMMA:
Core-shell ACR 5-8%
Light transmission >92%, 3 times higher impact strength
3.Composite Materials
Carbon fibre reinforced epoxy resin:
CTBN modified (10phr)
G₁C upgraded from 200J/m² to 800J/m²
Wood-plastic composites:
EVA toughening agent 3-5%
Flexural modulus retention >85