(1) If internal and external lubrication are both insufficient. It will be high melt viscosity, high plasticizing
torque, serious melt wall sticking phenomenon and non-smooth inner surface; serious thermal
decomposition in advance, low mechanical properties of products. If the internal and external lubrication
are balanced, the melting test material will come down as soon as it touches, and the surface of the rotor
will not stick to the melt material.
(2) If internal and external lubricants are both excessive. The plasticizing torque is small and have
precipitation occurs. Although the product has good smoothness, but its mechanical properties are low ,
easy broke. When it is serious, the surface of plastics will feel oily when wiped by hand.
(3) If less internal lubricants and more external lubricants. The plasticizing time is obviously prolonged,
because the internal lubricant is less, the internal friction of resin is larger, and it is easy to cause
thermal decomposition. The plasticizing torque increases. Sometimes it feels oily on the surface of the
sample by hand, and the product becomes broke
(4) If more internal lubricants and less external lubricants. The plasticizing time is obviously shortened,
so that the resin is plasticized ahead of time, resulting in the high viscosity melt being subjected to
shear force for too long, at the same time, there is a serious adhesion phenomenon, the rotor is not
easy to clean, also resulting in the shortening of thermal stability time, products have decomposition
In a word, if the amount of external lubricant is insufficient, there will be adhesion, short plasticizing
time and non-smooth surface of the sample; if the amount of external lubricant is excessive, plasticizing
time will beobviously prolonged, mechanical properties will be reduced, brittle, precipitation may occur,
and oil-like feeling will be felt when the exterior lubricant is excessive. When the amount of internal
lubricant is insufficient, the plasticizing torque will be larger and the plasticizing time will be longer;
when the amount of internal lubricantis excessive, the plasticizing time will be shorter and the
plasticizing torque will be smaller, but the thermal stability time will also be shorter, and there will be
thermal decomposition phenomenon, and the inner wall of the sample will not be smooth.
Usually the tensile strength is the highest when the plasticity is 60%, the impact strength is the highest
when the plasticity is 65%, and the elongation at break is the highest when the plasticity is 70%.