Will the Acrylic Swimming Pool Turn Yellow after Long-term Use?

The weather resistance of acrylic swimming pool is directly related to its material chemical structure. The carbonyl and double bond residues in the molecular chain of polymethyl methacrylate become active sites for photooxidation reaction. Industrial-grade acrylic controls the residual monomer concentration through bulk polymerization process, and introduces ultraviolet absorbing groups in the prepolymerization stage to form an intramolecular energy transfer mechanism. Ordinary acrylic sheets use suspension polymerization process, and their end group defects and impurity content are high. Under the coupling of long-term water immersion and light, the main chain is more likely to break.

The transparent laminated structure of acrylic swimming pool adopts co-extrusion technology to form an anti-yellowing shielding layer on the surface, which absorbs high-energy ultraviolet rays through benzotriazole compounds to block free radical chain reactions. Inferior products often use surface coating protection, and their silicone wear-resistant layer will gradually fail under the erosion of circulating water treatment agents. The matching degree of the thermal expansion coefficient of the acrylic swimming pool material itself and the glass fiber reinforcement layer affects the probability of microcrack generation under temperature alternating stress. The expansion of cracks will accelerate water vapor penetration and induce yellowing.

The temperature gradient control of the mold in the injection molding process affects the distribution of crystallinity. The interface between the high-crystallization area and the low-crystallization area is prone to become a light scattering center, resulting in visually perceived yellowing. If the thermoforming temperature during the secondary processing exceeds the glass transition range of the material, it will cause polymer chain scission to produce chromophores. The professional maintenance system can effectively delay the yellowing process of the acrylic swimming pool caused by the accumulation of oxidation products by regularly using non-ionic surfactants to remove organic pollutants adsorbed on the surface.