PP/PE toughening system
The toughening effect of LDPE on PP is obvious, but other mechanical properties such as flexural modulus decrease rapidly.
When the content of HDPE in PP is less than 10%, it has a rigid toughening effect on PP, that is, while increasing the impact property, other mechanical properties do not decrease.
The toughening effect of LLDPE on PP is between LDPE and HDPE, and the addition of 5- 20% is good.
UHMWPE has not only toughening effect on PP, but also in situ fiber forming.
PP/EVA toughening system
EVA can also improve the elongation at break, melt flow index and surface gloss while toughening PP. and the content of VA in the selected EVA is between 14% and 18%. The impact strength of PP was increased by 12 times with 20% EVA-15, and the decrease of rigidity was small.
mPE/PP toughening system
MPE has very low glass transition temperature and high elongation at break, which is suitable for toughening modification of PP.
The notched impact strength of PP was 20 times higher than that of pure PP at -30 ℃, which was about 9 times of that of EPDM of the same mass fraction. Composites with low tensile permanent deformation, compression permanent deformation and creep deformation, excellent low temperature type energy and processing properties, become a strong competitor to EPDM.
POE toughened PP system
PP/POE is an elastomer toughened PP system developed in recent years. It has the best toughening effect, good weathering resistance, good fluidity, good thermal stability and good processability. It is also the most commonly used elastomer toughened PP system.
When the amount of POE in PP is more than 15%, the toughening effect is improved rapidly. For example, when 30% POE is added to PP, the notch impact strength increases from 76.4J/m to 626J / m. Compared with EPDM, POE has low cohesive energy, no double bond and good weather resistance. It is a powerful substitute for EPDM.
SBS toughened PP system
When the content of SBS is in the range of 0-10 phr, the impact strength increases with the increase of the content of SBS, but decreases when the content of SBS is more than 15 phr. For example, the impact resistance PP made of SBS and PP at room temperature and low temperature is increased by 5 times and 10 times, respectively.
EPDM,EPR toughened PP system
EPDM (ethylene propylene diolefin terpolymer), EPR (ethylene propylene binary copolymer) is the most commonly used elastomer toughening material of PP. In the range of 5- 30%, the impact strength of the system increases linearly and linearly with the increase of the content, but at the same time, the bending strength, tensile strength and thermal deformation temperature of the system decrease obviously.
BR toughened PP system
Cis-butadiene rubber (BR) has the advantages of high elasticity, good low temperature properties (glass transition temperature -110 ℃), wear resistance, flexural resistance, etc. The solubility parameter of BR is close to that of PP, the compatibility with PP is good, and the toughening effect is good. When the PP/BR is 100/15, the impact strength increases nearly 6 times, and the embrittlement temperature drops to 8 ℃ (drop by 23 ℃).
The Synergistic toughening PP system of Plastics / Elastomer
Although the blend of elastomer and PP has excellent impact strength, but the properties of rigidity, strength and thermal deformation temperature are greatly lost, and the cost is obviously increased. In order to improve the mechanical properties and reduce the cost, the elastomer / plastic / PP ternary blend system was formed by adding plastics into the elastomer / PP toughened system.
