Waste PP recycling technology
Polypropylene (PP) is currently the second largest general-purpose plastic. With the development of industries such as construction, automobiles, home appliances and packaging, waste PP has become one of the largest waste polymer materials in recent years. At present, the main ways to deal with waste PP are: incineration for energy supply, catalytic cracking to prepare fuel, direct utilization and recycling. Considering factors such as technical feasibility, cost, energy consumption and environmental protection in the process of processing waste PP, recycling is the most commonly used, effective and most advocated way to deal with waste PP.
Due to the influence of factors such as light, heat, oxygen and external force during use, the molecular structure of PP will change, and the product will become yellow, brittle, or even cracked, resulting in PP toughness, dimensional stability, thermo-oxidative stability and workability. It is obviously worse, and it is difficult to directly use waste PP to manufacture products to meet the requirements of processing and use.
Therefore, the recycling technology of waste PP continues to develop. Alloying with other polymers or compounding with fillers can significantly improve the processing performance, thermal properties, physical and mechanical properties of waste PP, and realize the high performance of waste PP.
alloying
Alloying is the process of mixing waste PP with other polymer materials to prepare macroscopically homogeneous materials. By selecting different polymer materials for alloying, the processing properties, physical and mechanical properties of waste PP can be improved. For example, the use of elastomers can significantly improve the impact toughness of waste PP.
There are studies on the mechanical properties and thermal deformation behavior of waste PP/RU composite rubber (natural rubber and styrene-butadiene rubber each account for 50%). The continuous phase of waste PP can significantly improve the impact strength and elongation at break of waste PP, but it will reduce the rigidity and thermal deformation resistance of PP.
Because most elastomers are incompatible with waste PP, the interface bonding is poor, and there is phase separation during processing and use, which affects its performance. In order to improve the interfacial compatibility of waste PP alloys and enhance the interfacial adhesion, many scholars have carried out extensive research and found two kinds of materials that can enhance the interfacial adhesion of the blended materials and improve the storage modulus, loss modulus and system viscosity of the blended materials. compatibilizer.
The vulcanizing agent can improve the impact and tensile strength, melt viscosity, elongation at break and ductility of the blended material; the addition of the peroxide crosslinking agent can further improve the compatibility of the blended material and improve the blended material. impact and tensile strength, but resulted in a slight decrease in elongation at break.