7 major problems in extrusion production applications

A: No, because tetrafluoroethylene and related polymeric plastics are the same as polyethylene, and water molecules cannot penetrate through them, so they have a barrier to water.

Question 2: Processor manufacturers claim that PVC molds are harmful, is it true?

A: This statement is one-sided. Almost any manufacturing process, sports, driving or even cooking in the kitchen is dangerous if you are not careful.

Most of the time they refer to the fact that at very high temperatures, PVC will release hydrochloric acid gas. This gas can corrode unprotected surfaces on the mold, even the steel portion of the outer layer of the mold. This can be avoided by maintaining a lower melt temperature, a reasonable stabilizer formulation and a venting area.

Stainless steel molds are often used in the production process of extrusion equipment, but in fact ordinary steel can be replaced, as long as the formula is reasonable, the melt is in a flowing state and the temperature is not too high, and the most important point is that it occurs. In the event of a breakdown, the production line can be stopped and cleaned in time. Some other plastics (such as PDVC) also use some special building materials, such as nickel-containing materials.

Once the PVC is plasticized (such as a hose or wire insulation), it is often less problematic because plasticizers can only be used at lower temperatures. As for personal safety, hydrochloric acid gas has a strong pungent odor, which usually makes people have to stay away before a serious danger occurs. The best way is to strictly comply with the safety standards of the above conditions to avoid the volatilization of hydrochloric acid gas.

Question 3: Can we recycle polycarbonate?

A: Yes, but you must be careful that the liquid molecules in the melting phase must be dehumidified, dried or related to the process as the original material. The recycling of PCs and all other polyesters has the potential to be contaminated. Before you want to safely reproduce, you must use some physical strength to clean up the classification. Some may directly see from the color whether it may be contaminated (such as the color turns yellow), then the production method should be determined according to the reuse.

Question 4: Can the mechanical and elastic properties of the polymer be controlled by controlling the length of the polymer chain?

A: Yes, that's the main aspect: chain length = stronger melt viscosity of the material, but there are other factors in the production process, such as dispersants, additives and other additives that may be used.

Question 5: Will nylon products become soft after absorbing moisture from the air?

A: Yes, water can produce plasticizers. Nylon products absorb 1% to 2% of their own weight, depending on the type of nylon and the surrounding humidity and temperature. This is also the reason why the physical properties of nylon, such as tensile and impact strength, are good under experimental conditions, but the difference is large after practical application.

Question 6: Are plastic products a petroleum-based by-product?

A: Not exactly. This depends on the materials used in the products, such as polyethylene, polypropylene, polystyrene, etc. Most of them are based on petroleum refining, while PVC contains 56% chlorine. It is the smallest plastic product that relies on oil, and its production only needs to be compared. Less energy. Unfortunately, many people just discovered the adverse effects of PVC on the environment but ignored the environmental benefits of PVC.

There are also a number of plastics that are not used in petroleum-based sources, such as the oldest plastics, cellulose acetate, and esters of the same nature. Nylon 11 and nylon 10 are also not dependent on petroleum because they are based on castor oil. Recently, many plant-based plastics are rapidly developing, using corn, sugar or other organisms as raw materials. Some new plastics have biodegradable bioactivity, and petroleum-based PE or PP materials have similarities.

Question 7: How do we know the molecular structure... how much carbon, hydrogen, chlorine?

A: The structure of the monomer molecules is known - for example, each ethylene molecule CH2 = CH2, contains 2 C and 4 H, if we collect 7 such gas molecules, it must be 14 C and 28 H. Of course, if it is 1000 aggregate chains, there must be 2,000 C and 4000 H.

The same principle applies to other more complex polymers, and sometimes we have to calculate the water molecules (2 H, one O) lost during the polymerization process. However, most people do not need to know the composition of these atoms. They are more concerned with the nature of the polymer, depending on how they are combined, and the number.