The green cinnamaldehyde (CA) and thymol (THY) separately or successively modified O-ZnO (O-ZnO-CA, O-ZnO-THY, and O-ZnO-CA-THY) were prepared after (3-aminopropyl) triethoxysilane (KH550) was grafted to the surface of ZnO (O-ZnO) and characterized by FTIR, TGA, and SEM. Polypropylene composites (PP/O-ZnO-CA, PP/O-ZnO-THY, and PP/O-ZnO-CA-THY) were prepared by melting the modified O-ZnO and PP. The antibacterial tests showed that the antibacterial rate of PP/O-ZnO-CA and PP/O-ZnO-THY against S. aureus and E. coli was obviously enhanced. It indicated an excellent synergetic antibacterial effect of O-ZnO and the little CA or THY grafted on the surface of O-ZnO. The antibacterial effect of O-ZnO-CA and O-ZnO-THY was related to the hydrophobic and hydrophilic groups contained in CA and THY. Importantly, CA and THY in O-ZnO-CA-THY exhibited another excellent synergetic antibacterial effect against both S. aureus and E. coli. The antibacterial rate of three PP composites containing 4 phr O-ZnO-CA-THY against S. aureus and E. coli reached 95% and 90%, respectively. The mechanism was regarded as that CA and THY grafted onto the same O-ZnO improved the contact probability between antibacterial agents and bacteria. Moreover, O-ZnO-CA, O-ZnO-THY, and O-ZnO-CA-THY had excellent migration resistance in the PP matrix.

Two kinds of modified melamine–formaldehyde (MF) resin with high impact strength were prepared, especially the modified MF resin with the special “building blocks” structure. First, three copolymers (HMM‐PEGDGE, HMM‐PPGDGE, and HMM‐C12‐14AGE) of glycidyl ether [polyethylene glycol diglycidyl ether (PEGDGE), polypropylene glycol diglycidyl ether (PPGDGE), C12‐14 alkyl glycidyl ether (C12‐14AGE)] and hexahydroxymethyl melamine (HMM) were synthesized and proved by FTIR and 1H NMR. Then, the copolymers were mixed with melamine–formaldehyde resin water solution to prepare samples (EMM1‐PEs, EMM1‐PP, and EMM1‐C12‐14) through drying and hot pressing. The results indicated that the addition of HMM‐PEGDGE could significantly improve the impact strength of EMM1‐PEs, much higher than EMM1‐PP and EMM1‐C12‐14. Meanwhile, PEGDGE was also directly mixed with melamine–formaldehyde resin water solution and made into samples (EMM2‐PEs). The results showed that the impact strength of EMM2‐PEs was also higher than pure MF but lower than EMM1‐PEs. The impact strength of EMM1‐PE‐20 reached 9.46 kJ/m2, about two times that of pure MF. The mechanism of EMM1‐PEs with high impact strength was ascribed to the special “building blocks” structure, which had the flexible HMM‐PEGDGE block, could cause many cracks because of the poor compatibility between HMM‐PEGDGE and melamine–formaldehyde resin.