Modification and utilization of the hottest recycl

2022-08-26
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Modified utilization of recycled polypropylene (PP)

the tensile strength of recycled PP is low. The temperature rise of the former is much lower than that of the latter, which is about 18~25mpa. After being reinforced with short glass fiber (SGF), its tensile strength can reach about 30~35mpa. In order to improve the interface performance between fiber and resin, commonly used coupling agents such as KH550, KH560, KH570, etc. the amount of coupling agent is generally 0.2% to 1.5% of the fiber content. It is necessary to test and determine for different situations

chlorination of polypropylene:

recycled PP can also be chlorinated like recycled PE. Chlorinated products are widely used. For example, chlorinated app (CAPP) can be obtained by chlorination of app, which has excellent bonding performance and can be used to bond PE, PVC, PA, metal and other materials, such as packaging composite film, double-layer PP film, PP film paper, PP film aluminum foil and other adhesives. In addition, CAPP can also be used as a processing aid for coatings, printing inks and polar resins

Grafting modification of polypropylene:

chemical modification of polypropylene also includes grafting, block copolymerization and other modification. The purpose of polypropylene grafting modification is to improve the adhesion or solubilization of polypropylene with metals, polar plastics and inorganic fillers. The grafting monomers used are generally acrylic acid and its esters, maleic anhydride and its esters, maleimide, etc. from January 2018. The grafting methods are: ① solution method, adding peroxide initiator in the solvent for copolymerization; ② Radiation method, grafting under high-energy rays; ③ Melt mixing method, in the presence of peroxide, is mixed in the opposite state of melting but fatigue testing machine for grafting, which is often carried out in twin-screw extruder. The properties of grafted polymer materials are related to the physicochemical properties of the grafted products, and also to the content of the grafted products. The reliable stability is mainly reflected in the length of the grafted chain. Its basic properties are similar to polypropylene, but its compatibility with polar polymer materials, inorganic materials, rubber, etc. can be greatly improved. The crystallinity and melting point of grafted PP decrease with the increase of the content of the grafted products, Transparency and low temperature heat sealing are improved

crosslinking modification of recycled polypropylene:

recycled polypropylene can also be crosslinked like polyethylene, and the modification mechanism is similar to the polyethylene crosslinking introduced above

catalytic cracking and thermal cracking of polypropylene:

polypropylene is cracked at about 380~c, which can be thermally and catalytically cracked. Using silicon/aluminum powder (Si02/al:03) as catalyst, the catalyst can contact with the gas phase and liquid phase of pyrolysis products. The results showed that 69% liquid products with boiling point of 30~270 ℃, 2 · C6 to n-c1s paraffin oil, could be obtained by liquid phase contact catalyst method; Gas phase contact catalysis can obtain 54% (mass fraction) of liquid products, and the rate of obtaining products is much lower. The research on catalytic and non catalytic degradation shows that the unsaturation of the liquid products of catalytic degradation is much higher than that of non catalytic degradation, and the pyrolysis products are also different

polypropylene decomposes around 40013 under the action of catalyst, which can produce a series of substances. The research shows that the increase of catalyst content can improve the liquid yield, while the amount of gas and residue can be reduced; The type of catalyst has little effect on the yield and composition. Temperature has an effect on the cracking reaction. With the increase of temperature, the liquid yield increases, while the percentage of residue decreases, and the amount of gas slightly decreases. Cracking atmosphere has an effect on cracking products, and cracking in steam atmosphere can improve the liquid yield. In addition, no products other than the cracking products of the polymers themselves were found in the mixing of other waste plastics, that is, there was no interaction such as synergistic reaction in the cracking reaction. Under the condition of medium temperature cracking, the liquid forming rate is about 70%, and the liquid forming rate can be increased to about 85% by appropriately improving the technology

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