Abstract: The invention discloses an in situ polymerized flame retardant, derived from the following monomers: a diacid monomer A: where A1 is terephthalic acid, A2 is a phosphorus aromatic ring-containing reactive flame-retardant diacid monomer, A1+A2=100 mol %, A1=50 to 90 mol %, A2=10 to 50 mol %; and a diamine monomer B: one or more of diamine monomers containing 4 to 36 carbon atoms. In the present invention, a novel flame retardant is obtained by in situ polymerization of the phosphorus aromatic ring-containing reactive flame-retardant diacid monomers in semi-aromatic polyamide oligomers, which has advantages of no precipitation in the semi-aromatic polyamide and no influence on other properties of the semi-aromatic polyamide and has an excellent flame-retardant property.

Abstract: The invention discloses a flame-retardant semi-aromatic polyamide derived from the following monomers: a diacid monomer A: where A1 is terephthalic acid or terephthalic acid and other diacid, terephthalic acid accounts for 50 to 100 mol % of A1, and A2 is [(6-oxido-6H-dibenzo-(c,e)(1,2)-oxaphosphorin-6-ketone)-methyl]-butanedioic acid, A1+A2=100 mol %, A1=90 to 99 mol %, A2=1 to 10 mol %; and diamine monomer B: one or more of diamine monomers containing 4 to 36 carbon atoms. In the present invention, by an in situ polymerization, a specific flame-retardant monomer [(6-oxido-6H-dibenzo-(c,e)(1,2)-oxaphosphorin-6-ketone)-methyl]-butanedioic acid is copolymerized in a semi-aromatic polyamide chain segment, excellent mechanical properties and low water absorption can be obtained.

Abstract: The present invention provides a polyformaldehyde composite material, in parts by weight, including the following components: 70 to 95 parts of a polyformaldehyde; 5 to 20 parts of a SEBS; wherein, the SEBS is acid modified or amine modified. Due to modification by acid or amine, and presence of a polystyrene segment, a compatibility of the SEBS with the polyformaldehyde reduces because of a steric hindrance effect, which reduces an ability of a POM molecular chain to arrange regularly. When injection molded into a product or template, an incompatibility of the material itself will form a micro-rough effect on a surface of the material. When an incident light reaches the micro-rough surface, a reflection direction of the light will change and thus a diffuse reflection occurs, and a low-gloss material is obtained.