What is the heat resistance of Stone Garden Decor products and how much temperature can they withstand? Recently, many customers and friends have asked this question. The heat resistance of Stone Garden Decor products with different requirements is different. The main reason is that different resins correspond to Stone Garden Decor. The heat resistance ranges are also different, but why do different resins have different heat resistance levels?
The heat resistance of Stone Garden Decor is reflected in the fact that as the temperature increases, the mechanical properties of the resin matrix (such as bending strength, modulus, shear strength, etc.) will gradually decrease, resulting in the overall mechanical properties of the Stone Garden Decor. reduce. Fundamentally speaking, the heat resistance of Stone Garden Decor mainly depends on the resin matrix. After all, the ordinary type of
stone sculpture fiber has a temperature resistance of over 350°C, which is generally more heat-resistant than the matrix. Theoretically, the heat resistance mechanism can be summarized into the following aspects:
1. Molecular bond weakening theory
As the temperature increases, the molecular bonds between the matrix and the interface will weaken and the kinetic energy will increase, which may cause some bonds to break under a certain load.
2. Microcrack theory
Due to the difference in thermal expansion coefficient between the fiber and the matrix, as the temperature rises, thermal stress is generated and micro-cracks are prone to occur. At the same time, during the curing process, bubbles or impurities are present in the matrix to form defects. After the temperature rises, the air expands due to heat. , increase the formation of cracks, which will reduce the mechanical properties of the material to some extent.
3. Resilience theory
The matrix has a certain inhibitory effect on fiber defects and can limit the expansion of the fiber damage area. As the temperature increases, the toughness of the matrix becomes larger and the inhibition on the fibers weakens. The damage area will expand and the strength will decrease accordingly.
Combined with the above heat resistance mechanism, what are the ways to improve the heat resistance of Stone Garden Decor?
1. Increase the stone transformation temperature Tg, which is a physical quantity that measures the characteristic temperature of polymer chain segment operation. Increasing the
stone carving transformation temperature means increasing the degree of cross-linking of the resin to make its structure more stable; the usual method is to introduce a heat-resistant skeleton and add naphthalene rings, aromatic rings, heterocyclic rings, etc. to the resin to improve thermal stability; choose high-quality Performance curing agent; post-curing treatment, etc.
2. Strictly control the production and curing process, pay attention to details, and try to avoid defects and cracks.
3. Moisture-proof treatment. Reinforcement materials such as fibers and fabrics should be kept as dry as possible during use and dehumidified if necessary. On the one hand, moisture absorption will increase the thermal expansion coefficient of the resin matrix and have a plasticizing effect on the resin, which will decrease the stone transformation temperature of the resin matrix and reduce the modulus; on the other hand, it will easily diffuse through the resin matrix to the interface, causing the interface to The bonding force is weakened, so the matrix can be made of resin with low moisture absorption, or adding a hydrophobic agent to the resin can improve its heat resistance.
4. Ensure a good bonding interface and select matching fibers and resins. For thermoplastic composites, the crystallinity of crystalline composites can be increased to improve heat resistance.
5. Add resins with good heat resistance such as polyimide and bismaleimide to the resin, or add thermoplastic high-temperature resistant resins such as PEEK, but the compatibility with the original resin must be considered to improve the composite material. heat resistance.
Heat resistance is only one of the properties of Stone Garden Decor. In the design of materials and processes, other properties must also be taken into consideration, and they may conflict with each other. Comprehensive considerations are required to select the material system and corresponding molding process.
