In order to improve the aging resistance of heat shrinkable tubes, antioxidants and ultraviolet shielding agents should be added. Generally, phenolic antioxidants, such as antioxidant 1010, are used as the main antioxidant, and tdpa February cinnamon vinegar is used as the auxiliary antioxidant. Carbon black has a good ultraviolet shielding effect. Adding 2.6% carbon black into the heat shrinkable tube can make the outdoor service life of the heat shrinkable tube exceed 20 years.

    X-ray energy and irradiation agent Z are the decisive factors affecting the degree of crosslinking. The energy of X-ray mainly depends on the type of radiation source. 60Co can produce 1.173-1.332MeV Y-ray, and electron accelerator can produce 3-630MeV high-energy electron beam. The depth of action (penetration ability) on polymer varies with the type and energy of radiation. The penetration ability of electron beam is limited to millimeter level, while the depth of 1.332MeV Y ray produced by Co can reach more than 300nun.

    In the production of heat shrinkable materials at home and abroad, electron accelerators are mostly used as radiation sources, and the energy of electron beams is generally 2-3MeV. When determining the irradiation dose, on the one hand, the necessary gel content should be ensured, and on the other hand, the irradiation stability of the irradiated polymer should be considered. The irradiation dose of polyethylene is 20-30Mrad. The irradiation stability sequence of common polymer materials, when choosing irradiation dose, should be lower than the damage dose given in the table.