Abnormal mechanical properties of composites based on boron oxide oligomer/polyethylene blends

The mechanical properties of composites based on the inorganic boron oxide oligomer (BOO) and low‐density polyethylene (LDPE) produced by extrusion and injection molding have been studied in the range of volume fractions of the inorganic component from 0 to 64 vol%. An abrupt increase in the Young's modulus and ultimate tensile strength of the composites in the vicinity of 30 vol% BOO has been found. These critical properties are accompanied by a stepwise decrease in the elongation at break at the same volume fraction of the inorganic component. The mechanical properties of BOO/LDPE composites were compared with the same characteristics of composites based on LDPE and polymethyl methacrylate prepared via a similar way. The electron microscopic examination has suggested that the abnormal concentration dependences of the Young's modulus, tensile strength, and elongation at break of BOO/LDPE composites are conditioned by the formation of the unidirectional microfibers of the inorganic oligomer as soon as its volume fraction exceeds the critical threshold. POLYM. COMPOS., 40:916–923, 2019. © 2018 Society of Plastics Engineers