The thermal conductivity of EPS particles is a key indicator of its thermal insulation performance. Accurate measurement of thermal conductivity is crucial to evaluate the suitability of EPS particles in many areas such as building insulation and cold chain packaging. Usually the heat flow meter method or the guarded hot plate method is used for measurement. During the measurement process, factors such as sample preparation, temperature and humidity of the test environment need to be strictly controlled to ensure the accuracy and reliability of the measurement results. For example, samples should have uniform density and thickness to avoid deviations in thermal conductivity measurements due to differences in internal structure.
The microstructure of EPS particles has a significant impact on thermal conductivity. It contains a large number of closed pores inside. The thermal conductivity of gas is much lower than that of solid polymer, so the existence of pores effectively reduces heat conduction. However, the size, distribution, and connectivity of pores can affect thermal conductivity. Smaller, evenly spaced, independent pores better prevent heat transfer. For example, when the process of EPS particles is improperly controlled during the foaming process, larger pores or connected pores are produced, which will increase the thermal conductivity and reduce the thermal insulation effect.
Traditionally, the thermal conductivity of EPS particles has been reduced by optimizing the foaming process. During the foaming process, the type and amount of foaming agent are precisely controlled so that the foaming agent can be evenly dispersed and produce pores of appropriate size and number. For example, physical foaming agents such as pentane are used to form fine pores in EPS particles under appropriate temperature and pressure. At the same time, adjust the foaming temperature and time to avoid over-foaming or under-foaming to obtain the ideal pore structure, thereby reducing thermal conductivity.
In recent years, researchers have explored the use of new additives to further reduce thermal conductivity. Some nanomaterials such as aerogel, nanosilica, etc. are added to EPS particles. These nanomaterials have extremely low thermal conductivity and high specific surface area, and can be filled in the pores of EPS particles or attached to the particle surface, effectively preventing the conduction and radiation of heat through the pores. For example, when aerogel is added to EPS particles, it can significantly reduce thermal conductivity and improve thermal insulation performance without significantly increasing density.
In addition to additives, designing composite structures is also an effective way to reduce thermal conductivity. Compound EPS particles with other thermal insulation materials such as reflective films, vacuum insulation panels, etc. Reflective films reduce heat transfer by reflecting thermal radiation, while vacuum insulation panels utilize the internal vacuum environment to greatly reduce heat conduction and convection. For example, adding a layer of aluminum foil reflective film to the outer layer of an EPS insulation board can effectively block thermal radiation, reduce the overall thermal conductivity, and improve the thermal insulation effect.
In order to better reduce the thermal conductivity of EPS particles, process optimization and material innovation need to be coordinated. While improving the foaming process, rationally select additives and design composite structures, taking into account factors such as cost, performance and environmental protection. For example, when using nano-additives, it is necessary to ensure their dispersion in the foaming process to avoid agglomeration that affects the insulation effect, and at the same time control costs to make new EPS particles competitive in the market.
As the requirements for energy conservation and environmental protection continue to increase, the technology to reduce the thermal conductivity of EPS particles will continue to develop. More efficient, environmentally friendly and cost-effective methods of reducing thermal conductivity are expected to be developed in the future. For example, through the principles of genetic engineering or bionics, EPS particles with special structures are designed so that their thermal conductivity is close to the theoretical limit, providing better thermal insulation material solutions for areas such as building energy conservation and cold chain logistics.
