field of science and Technology

1. Project background:
   Radiation modification of polymer composites is an aspect of the application of radiation chemistry in the field of new materials and rapid development. Some composite conductive polymer materials have a positive temperature coefficient of resistance (PTC effect). Within a certain range, the resistivity increases with the increase of temperature, showing a sudden change of several orders of magnitude near the Curie point of the polymer. It is widely used in heat tracing temperature control, electromagnetic shielding materials and overcurrent protection. Among them, the most representative ones are self-controlled electric heating strips and radiation crosslinking, which can extend their service life.
2. Main technological innovation contents:
   1. Modification of nano-conductive particles, that is, nano-conductive carbon black is treated with a radiation emulsion method to graft or embed conductive and non-conductive polymers on the surface of carbon black, increasing the dispersion stability of nano-carbon black particles in polymer media., and at the same time reducing dust during processing. On this basis, polyolefin PTC conductive functional materials with high PTC strength and extremely high stability can be prepared.
   2. The positron annihilation characteristics of polyethylene and polyethylene/carbon black composites before and after irradiation were studied. The change of free volume with carbon black content in the polyethylene/carbon black composite system was studied using positron annihilation technology, which confirmed that carbon black particles were in the amorphous region. The view that free volume holes were correlated with the positive temperature coefficient (PTC) characteristics was verified, and the positron annihilation characteristics of the free volume model and the Spur model in polar polymers were compared. At the same time, combined with free volume theory, a new explanation of the PTC and NTC mechanisms is proposed, which has been recognized by international peers and used to guide the design of our material formulas.
   3. Reactive compatibilization technology, which introduces chemical effects during the processing of composite conductive polymer materials, so that chemical bonding exists between the polymer matrix and the inorganic filler. The dispersion stability of CB can be improved by using the interfacial energy of multiphase systems to prepare multiphase blends of PTC conductive functional materials. Adding silicone rubber and grafting PE can enhance the affinity between CB particles and PE.
   4. Successfully integrated PTC material preparation technology, product manufacturing technology, professional testing technology, and product application technology. By implementing a strict QC/QA quality control system, large-scale industrial production has been achieved, with no accidents for 5 million meters.
   3. Characteristics and papers
   1. Due to the high degree of blockade of this kind of product technology, Shanghai University has successfully developed a self-limiting heating/heating strip in response to the needs of the development of high-tech industries. It is widely used in industry for pipelines, valves, and supervision and inspection instruments in oil and gas fields and chemical plants. Antifreeze insulation; it can be used for antifreezing and insulation of solar water supply pipelines in civil use. Some performances of the product have exceeded the international level, and the price is only 1/2---1/3. It can be used for more than three years, and newly developed fluorine-containing flame retardant and explosion-proof belts and various low, medium and high temperature belts. Moreover, the used voltage can range from 12 - 600V, and the heating power per meter can range from 5 - 80W.
      Since the launch of this project, 6 invention patents have been applied, of which 2 have been authorized; 23 academic papers have been published in domestic and foreign journals and international conferences, 21 of which were searched by SCI/EI and cited 56 times by him. Exhibiting at the 8 th China Industrial Expo was well received.
   4. Application promotion
      Since the production of temperature-controlled electric heating/heating strip, it has sold a certain scale. Four extrusion production lines have been added, two sets of internal mixing and granulating systems have been added, and more than 40 new employees have been added. This achievement has been applied to electric heat tracing of the fire pipes of the Bird's Nest, the main venue of the Beijing Olympic Games; electric heat tracing of the fire supply pipes of the Beijing Capital Airport; electric heat tracing of the fire pipes of the Yantai World Trade Center and the melting snow and ice melting pipes of the Tiangou Port Ore Terminal; Electric heat tracing of the extraction and water pipes of the Wulashan Power Plant in Inner Mongolia; Electric heat tracing for the blast furnace project of Tangshan Gas Coking Plant; electric heat tracing for the oil pipeline of Qinjing Oil and Gas Branch; electric heat tracing for the water pipeline of the large garage of Taifeng Home in Tianjin Development Zone; electric heat tracing for tanks and pipelines produced by Aumigali (Dalian) Company; and key projects such as Tuha Oilfield in southern Xinjiang. It has sold more than 6 million meters, and customers have responded well. It has replaced similar foreign products and has good economic and social benefits.