Reclamation and Re-resource Of Fiber Reinforced Polymer Based Composites

1.       Mposition and recycling of fiber reinforced resin matrix composites

1.1   Thermoplastic resin base

Fiber reinforced thermal plastic recycle and pure thermoplastics (FRTP) recycling some similar, but there in the FRTP enhancement phase, and enhance the phase structure and distribution characteristics of greater influence on the performance of the materials, so its recovery processing is much more difficult than pure thermoplastics, and recovery processing after the change of its mechanical properties is also a focus of concern. In the past, high industrial costs and cumbersome recycling processes meant little attention was paid to recycling, resulting in the accumulation of waste fibre-reinforced plastics in factories. With the intensification of business competition, the enhancement of environmental protection awareness and the pressure of resource depletion globally, more and more factories have processed and recycled their wastes, and great progress has been made in the recycling and utilization of fiber-reinforced plastics internationally.

1.2 Thermosetting resin base

In contrast, the separation and recovery of fiber reinforced thermosetting resin matrix composites is more difficult due to the three-dimensional network structure formed after molding. According to the recovery process, there are two methods: one recovery and three recovery. Secondary recycling refers to the use of waste materials to be mechanically crushed, used as a filler for the preparation of new composite materials, or directly used to fill thermoplastics. This process only requires mechanical action and is a physical change process. The three times recovery method means that the thermosetting resin matrix is decomposed into its low molecular substance by heating it in different media or through chemical reaction, so as to achieve the separation from the reinforcing material and realize the purpose of recovery.

A granulator is used to granulate the chip molding (SMC) fragments. The glass fiber in the granule still has the basic size (the fiber length-diameter ratio is greater than the critical value) and filling into the plastic has a reinforcing effect. In addition to the mechanical recovery of unsaturated polyester SMC, thermosetting phenolics are also commonly recovered by this method. During the crushing process, the fiber is separated from the brittle epoxy resin matrix to obtain a mixture of particles and staple fibers, and then the secondary pulverized particles are recycled according to different particle sizes and fiber lengths through screening or air separation. The results showed that the mechanical properties of long fiber reinforced plastics were improved by adding recycled materials in PA6.

The decomposition of polymer materials by supercritical fluid is a new technology developed in recent years, especially in thermosetting plastics. The liquid phase consists of medium and low molecular weight organic materials, and the solid phase is fiber. The obtained fiber has no obvious difference compared with unused fiber after electron microscope observation, and there is no organic material on the fiber surface, so it can be used again as reinforcing material. Studied the decomposition and recycling of carbon fiber/phenolic composite materials, and found that in the supercritical water reaction medium system in alkaline environment, increasing temperature, prolongation of time and increasing alkali concentration would be beneficial to the decomposition of resin matrix.

2.       Separation and recycling of fiber reinforced rubber matrix composites

Short fiber reinforced rubber composite (SFRC) is an important part of rubber products. The main recycling ways of waste SFRC are to produce recycled rubber and waste rubber powder. Taking tires as an example, at the end of the 20th century, the world produced more than 10,000,000 tons of waste tires every year, and our country was close to 10,000,000 tons of waste tires. In the process of producing recycled rubber from waste tires or other waste rubber products, at least 5 waste fibers were generally produced, and the output was very considerable. For environmental protection and security needs, most of the reclaimed rubber factory installed with waste fiber recycling equipment, but due to technical or economic reasons, such as waste fibers were used as the fuel burn more, make the fiber more than on attached vulcanized rubber produces a large number of our fleet and s02 gas, serious atmospheric pollution and the surrounding environment, and can make the fiber of recycling waste materials.

Fortunately, people have paid more attention to the research and application of this field. An earlier overseas for recycling waste fiber, carrying out the work are mainly concentrated in the field of building materials and rubber, synthetic fiber cord scrap filling on the coagulation of the tensile strength, impact strength and tensile strength increased, and the craft simple, the cost is not high, when used as waterproof tarpaulins, runway pavement materials, not only reduce the cost, and can improve the tensile strength and resistance to puncture strength. The experiment shows that although the waste rubber has been damaged to some extent during the regeneration process, it still has certain mechanical strength, especially synthetic fiber, which still has the characteristics of good elasticity, high abrasion resistance and excellent dielectric resistance. Although the surface of these waste fibers is coated with broken rubber residue and rubber powder, their potential utilization value can be fully developed through proper processing.