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15 questions for you to really understand plastic processing aids!

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15 questions for you to really understand plastic processing aids! | 2016-11-03 |
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1. What is a polymer material processing aid? what is the function?

Answer: Additives are various auxiliary chemicals that need to be added during the production or processing of certain materials and products to improve the production process and product performance. Resins and raw rubber are processed into plastics and rubber products. Various auxiliary chemicals needed.

Role: ①Improve the technological performance of polymers, optimize processing conditions, and submit processing efficiency; ②Improve the performance of products, increase their use value and life.

2. What is the compatibility of additives with polymers? What is the significance of spraying and sweating?

Answer: Spray polymerization-precipitation of solid additives; sweating-precipitation of liquid additives. Compatibility of auxiliaries and polymers refers to the ability of auxiliaries and polymers to be uniformly and mixed together for a long period of time without precipitation of phase separation.

3. What is a dendrimer?

Answer: Dendritic Polymers are known as the "newest fourth-class new polymer" materials, which are nanomaterials in the frontier new materials field. A new type of polymer with a dendritic structure and a large number of functional groups on the surface, has Good melt viscosity and modification space have attracted the attention of the scientific and industrial circles.

Dendritic structure

4. What are the unique advantages of the latest fourth-generation dendrimer as a plastic additive?

Answer: As a nylon lubricant , the modified dendritic polymer material is different from traditional lubricants, which can double the fluidity of nylon processing on the basis of ensuring mechanical properties; as a PP toughener , The modified dendrimer has flexible polyolefin long segments, which acts as a link and buffer between molecular chains. At the same time, the dendrimer has a spherical structure with a smaller hydrodynamic radius. It has significant low melt viscosity characteristics, which can greatly improve the melt flowability of polyolefin materials such as PP.

5. What is the role of plasticizers?

Answer: Weaken the van der Waals force of the secondary valence bonds between the polymer molecules, thereby increasing the mobility of the polymer molecular chain and reducing the crystallinity of the polymer molecular chain.

6. Why is polystyrene more resistant to oxidation than polypropylene?

Answer: The unstable H is replaced by a large phenyl group. The reason why PS is not easy to age is that the benzene ring has a shielding effect on H; PP contains tertiary hydrogen and is easy to age.

7. What is the reason for the unstable PVC heating?

Answer: ① The molecular chain structure contains initiator residues and contains allyl chloride to act as an activating group. The terminal double bond reduces the thermal stability; ② The effect of oxygen accelerates the removal of HCL during the thermal degradation of PVC; ③ The HCl produced by the reaction has a catalytic effect on the degradation of PVC; ④ The effect of the amount of plasticizer.

8. Based on the current research results, what are the main effects of heat stabilizers?

Answer: ① Absorb and neutralize HCL and inhibit its autocatalytic effect; ② Replace the unstable allyl chloride atom in PVC molecule and inhibit the release of HCl; ③ Addition reaction with polyene structure, destroy the formation of large conjugated system Reduce coloration; ④ Capture free radicals and prevent oxidation reactions; ⑤ Neutralize or passivate metal ions or other harmful substances that catalyze degradation; ⑥ Protect, shield and weaken ultraviolet radiation.

9. Why is UV the most destructive to polymers?

Answer: The ultraviolet wavelength is short and the energy is large, which breaks most chemical bonds of polymers.

10. What kind of synergistic system does the intumescent flame retardant belong to, and what is its basic principle and function?

Answer: Intumescent flame retardants are phosphorus-nitrogen synergistic systems. Mechanism: When the polymer containing this flame retardant is heated, a uniform carbonaceous foam layer can be formed on the surface, and the word layer is thermally insulated, oxygen-proof, smoke-suppressed, and drip-proof, so it has good flame-retardant properties.

11. What is the oxygen index, and how does it relate to flame retardancy?

Answer: OI = O2 / (O2 + N2) × 100% In the formula, O2: oxygen flow; N2: nitrogen flow. The oxygen index refers to the volume percentage content of the minimum oxygen required in a nitrogen-oxygen mixed gas flow when a sample of a certain specification can continue to burn smoothly like a candle. OI <21 is flammable, oi is 22 to 25 with self-extinguishing property, 26 to 27 is non-flammable, and 28 or more is extremely difficult to burn. <p = "">

12. How does the antimony halogen flame retardant system work synergistically?

Answer: Sb2O3 is commonly used for antimony, and organic halides are commonly used for halides. Sb2O3 / organic halide is used together, mainly because it interacts with the halide emitted by the halide. And the product is thermally decomposed into SbCl3, which is a volatile gas with a relatively low boiling point. This gas has a relatively high density and can stay in the combustion zone for a long time to dilute the flammable gas, isolate the air, and play a role in blocking olefins. Second, it Capable of capturing flammable free radicals to suppress flame. In addition, SbCl3 condenses into droplet-like solid particles over the flame, and its wall effect scatters a large amount of heat, which slows down or stops the combustion rate. Generally speaking, 3: 1 is suitable for chlorine and metal atoms.

13. According to current research, what are the mechanisms of action of flame retardants?

Answer: ① The decomposition products of the flame retardant at the combustion temperature form a non-volatile and non-oxidizing glass-like film, which can block air from reflecting energy or have a low thermal conductivity.

② The flame retardant is thermally decomposed to generate non-combustible gas, which will dilute the flammable gas and dilute the oxygen concentration in the combustion zone; ③ the flame retardant melts and decomposes and absorbs heat;

④ The flame retardant promotes the formation of a porous, heat-insulating and carbon-stabilizing layer on the plastic surface, preventing heat conduction and continued combustion.

14. Why is plastic easily susceptible to static electricity during processing or use?

Answer: Because the molecular chains of the host polymer are almost all covalently bonded, they can neither ionize nor transfer electrons. During the processing and use of the product, when it wants to contact and rub with other objects or itself, it will be charged due to the gain and loss of electrons, and it will be difficult to disappear through its own conduction.

15. What are the characteristics of the molecular structure of antistatic agents?

Answer: R-Y-XR: lipophilic group, Y: linking group, X: hydrophilic group. In their molecules, the non-polar part of the lipophilic group and the polar part of the hydrophilic group should have a proper balance, and have certain compatibility with polymer materials, alkyl groups above C12 are typical lipophilic The hydroxyl, carboxyl, sulfonic and ether bonds are typical hydrophilic groups.


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