Resin coated sand (RCS) with phenolic resin matrix can hardly be collapsed when it is used in Al-alloy casting. Adding collapsing agent and reducing the concentration of resin are solutions adopted by workers. but these methods tend to reduce the initial strength of RCS. Synthesis of modified phenolic resin with direct-chain diacid DAn (/JS=6. https://darthomes.shop/product-category/storage-cabinets-2/