Explain to you whether silicone powder in the process of processing will lead to poor lubrication ef
來源：www.iceshenlan.cn 發(fā)布時間：2019年05月22日
Silicone powder is generally produced from high molecular weight organosilicone and silicon dioxide. Its main functions are:
1. Improve the plastics processing activity and demoulding, reduce the torque, reduce equipment wear, simple filling, reduce the rate of defect;
2. Decrease friction coefficient, improve smoothness, improve surface gloss, enhance silk texture touch, improve scratch resistance;
3. Improve flame retardancy, reduce smoke density, improve impact strength and gloss of flame retardant materials (high filling);
4. Excellent stability and non-mobility.
So when using silicone powder lubricant, in order to better fuse with raw materials, and add active function, reduce the viscosity, what should we do? Generally speaking, there are two aspects that affect the function of silicone powder lubricant:
One is temperature control.
One is shear rate.
Effect of Temperature on the Function of Silicone Powder Lubricant
With the increase of molecular thermal kinetic energy, the interaction force between particles, molecules and segments of PVC resin can be weakened, the activity can be improved, the melt viscosity can be reduced, and the internal lubricant of small molecules can easily enter between resin particles and molecular segments, and the compatibility and lubrication of internal and external lubricants, especially internal lubricants, can be increased.
2) Effect of Shear Rate on the Function of Silicone Powder Lubricant
Because thermoplastic resins are linear polymers, their main chains are very long, and many side chains surround each other, forming chaotic molecular groups, so their melt viscosity is very high. When the melt acts under shear force and heat, the conformation of the polymer chain changes.
That is to say, in the course of polymer chain activity, on the one hand, the molecular segments move, orient and straighten with the force, on the other hand, because the cohesion of the molecular segments is constantly rebounding and shortening.
When the shear rate increases a lot, the time of long chain activity (i.e. orientation and straightening) of melt is shorter than that of shortening and rebounding. Molecular chain has no time to rebound and shorten. Or the molecular chain of orientation only rebounds and shortens a part, so the resistance decreases when the shear rate decreases, so the viscosity of a proper part of resin melt decreases with the progress of shear rate.
From the microscopic point of view, the compatibility and lubrication effect of lubricants are added correspondingly when the shear rate is increased.
Therefore, the compatibility and lubrication of silicone powder can be improved by properly increasing temperature and adding shear rate.
1. Improve the plastics processing activity and demoulding, reduce the torque, reduce equipment wear, simple filling, reduce the rate of defect;
2. Decrease friction coefficient, improve smoothness, improve surface gloss, enhance silk texture touch, improve scratch resistance;
3. Improve flame retardancy, reduce smoke density, improve impact strength and gloss of flame retardant materials (high filling);
4. Excellent stability and non-mobility.
So when using silicone powder lubricant, in order to better fuse with raw materials, and add active function, reduce the viscosity, what should we do? Generally speaking, there are two aspects that affect the function of silicone powder lubricant:
One is temperature control.
One is shear rate.
Effect of Temperature on the Function of Silicone Powder Lubricant
With the increase of molecular thermal kinetic energy, the interaction force between particles, molecules and segments of PVC resin can be weakened, the activity can be improved, the melt viscosity can be reduced, and the internal lubricant of small molecules can easily enter between resin particles and molecular segments, and the compatibility and lubrication of internal and external lubricants, especially internal lubricants, can be increased.
2) Effect of Shear Rate on the Function of Silicone Powder Lubricant
Because thermoplastic resins are linear polymers, their main chains are very long, and many side chains surround each other, forming chaotic molecular groups, so their melt viscosity is very high. When the melt acts under shear force and heat, the conformation of the polymer chain changes.
That is to say, in the course of polymer chain activity, on the one hand, the molecular segments move, orient and straighten with the force, on the other hand, because the cohesion of the molecular segments is constantly rebounding and shortening.
When the shear rate increases a lot, the time of long chain activity (i.e. orientation and straightening) of melt is shorter than that of shortening and rebounding. Molecular chain has no time to rebound and shorten. Or the molecular chain of orientation only rebounds and shortens a part, so the resistance decreases when the shear rate decreases, so the viscosity of a proper part of resin melt decreases with the progress of shear rate.
From the microscopic point of view, the compatibility and lubrication effect of lubricants are added correspondingly when the shear rate is increased.
Therefore, the compatibility and lubrication of silicone powder can be improved by properly increasing temperature and adding shear rate.