Medical Rubber Parts Injection Molding Machine

Rubber Combining & It's Affactors:

• Bound rubber is also called carbon black gel (bound rubber), which refers to the part of the rubber in the carbon black compound that cannot be dissolved by the good solvent of the rubber. The bonded rubber is essentially the rubber adsorbed on the surface of the filler, that is, the rubber in the interface layer between the filler and the rubber. Bonded rubber is usually used to measure the size of the interaction between carbon black and rubber. If there are more bonded rubbers, the reinforcement is high. Therefore, bonded rubber is a measure of carbon black's reinforcing ability.
• NMR studies have confirmed that the thickness of the carbon black bonding adhesive layer is about 5.0nm, and the thickness of the layer next to the carbon black surface is about O.Snm. This part is glassy. 5mn. The side close to the rubber matrix is ​​sub-glassy with a thickness of approximately 4.5 mn.
• There are two reasons for the formation of the binding rubber.

1. One is that the rubber molecular chains adsorbed on the surface of the carbon black are combined with the surface groups of the carbon black, or the rubber products are mixed and vulcanized during the processing to produce a large number of rubber free radicals or ions. The carbon black is combined and chemically adsorbed, which is an important reason for the formation of the binding glue;
2. Second is the physical adsorption of the carbon black particle surface to the rubber macromolecular chain whose adsorption force is greater than the solubility.

Factors Affecting The Rubber Bonding:

1. Bonded rubber is produced due to the adsorption of rubber on the surface of carbon black, so any factor that affects this adsorption will affect the amount of bonded rubber produced. The main influencing factors are as follows.
2. The effect of the specific surface area of ​​carbon black The binding rubber is almost proportional to the specific surface area of ​​the carbon black. As the specific surface area of ​​carbon black increases, the binding rubber increases.
3. The effect of the number of mixing thin passes is absolutely 50 parts of carbon black in the rubber. The number of thin passes ranges from 0 to 50. The bonding rubber is the most separated at about 10 times, and it will decrease later, and it will stabilize after about 30 times. .
4. The changes of 50 parts carbon black filled chloroprene rubber, styrene butadiene rubber) and butyl rubber with the number of thin passes are as follows: Air-butadiene rubber, styrene butadiene rubber bonding rubber increases with the increase of the number of thin passes, and tends to about 30 times. In balance. But the butyl lamina drops at the beginning, but also tends to balance after about 30 times.
5. The influence of temperature Put the mixed samples at different temperatures for a certain period of time and then measure the amount of binding glue. As the processing temperature increases, the amount of binding glue increases. Contrary to the above phenomenon, the influence of the mixing temperature on the bonding rubber is that the higher the mixing temperature, the less bonding rubber.
6. The effect of the properties of rubber products The amount of binding glue is related to the unsaturation and molecular weight of the rubber. Rubber with high unsaturation and high molecular weight will produce more binding glue.
7. The test of the influence of aging time shows that as the parking time increases after mixing, the amount of binding glue increases, and it tends to balance after about a week.