There are many practical difficulties in the recycling and reuse of PPR tube with fiber. First of all, it stems from the complexity of its material composition. This type of pipe is usually a composite of PPR substrate and reinforcing materials such as glass fiber and carbon fiber. Although these reinforcing materials can improve the strength and heat resistance of the pipe, they will form physical entanglements during recycling, which will cause trouble for separation. For example, glass fiber has a high hardness and is easy to damage the equipment during mechanical processing. It is also difficult to completely separate it from PPR in a molten state, resulting in residual fiber impurities in the recycled material, affecting the effect of secondary processing. In addition, some pipes may contain metal parts or coatings, which further increases the complexity of sorting.
After long-term use, PPR tube with fiber will experience performance degradation due to factors such as oxidation and thermal stress, and the molecular chain will break, resulting in a decrease in the mechanical properties of the material. Such recycled materials are difficult to use in the production of products with high performance requirements, and can only be turned to low value-added fields, and the market demand is relatively limited. At the same time, PPR tube with fiber is mostly buried inside the building structure. When dismantling, it is necessary to destroy the wall or ground, and the labor cost is high. This high cost and low benefit situation makes recycling companies lack motivation. Many discarded pipes can only be mixed with construction waste and landfilled or incinerated.
The recycling process in the industry has formed some mature practices. Mechanical recycling is a common physical treatment method. The pipes are first crushed and decomposed into smaller pieces through a multi-stage crushing process. At the same time, impurities are removed by screening. After cleaning, high-pressure water flow and mechanical stirring are used to remove surface oil and concrete residues, and then PPR and reinforcing fibers are separated by density differences. The washed fragments will be melted, heated and melted by an extruder, and then granulated after filtering impurities through a filter. However, the residual fibers in this process will affect the fluidity of the material, and some additives need to be added to improve the processing performance.
Chemical recycling is also an effective treatment method. The solvent extraction method uses a specific solvent to dissolve PPR at a certain temperature, while the reinforcing material is left in solid form. This can achieve a better separation effect and obtain a higher purity recycled material, but this method requires a high recovery rate of the solvent, otherwise the cost will be too high. Thermal cracking technology is to heat and decompose the pipe in an oxygen-free or low-oxygen environment to obtain light hydrocarbons. At the same time, the by-product fiber material can also be used as filler. However, this process requires a large investment in equipment and a corresponding exhaust gas treatment system to control pollution.
In order to improve the performance of recycled materials, some modification technologies will also be used, such as surface treatment of recycled glass fibers, improving their bonding ability with the PPR matrix through coupling agents, thereby improving the strength of recycled materials; or adding nanomaterials to improve the heat resistance of recycled materials, but these methods need to solve the problem of uneven material dispersion, otherwise it may affect product quality.
The recycling and reuse of ppr tube with fiber faces many challenges such as material separation, performance attenuation and cost control. The mature processes in the industry have different focuses. Mechanical recycling is suitable for large-scale processing but is limited by materials. Chemical recycling can improve purity but the cost is high. Modification technology helps to expand the scope of application. In the future, continuous efforts will be made in process optimization and industrial chain collaboration to improve the efficiency and economy of recycling.
