Polyol and polyurethane containing bisphenol‐ Z : Synthesis and application for toughening epoxy

Self Cite

A curing agent is required to cure an epoxy resin, but a few curing agents also improve the mechanical properties of the resin. In addition, it is rare to find hardeners containing multiple amines, which can be used to form high crosslink densities. In this study, two different curing agents with six amine functional groups each were synthesized via a two-step reaction. In the first step, isophorone diamine (IPDI) was reacted with two equivalents of pentaerythritol triacrylate (PETA). The resulting IPDI-PETA2 was reacted with ethylene diamine and 4,4 0 -diaminodiphenyl sulfone to form two amine curers with six amines each-IPDI-PETA2-ED (ED) and IPDI-PETA2-DDS (DDS). Both amines were added in varying amounts to an epoxy composition consisting of dicyandiamide and 2-methylimidazole to improve the mechanical properties compared with a reference epoxy composition. Mechanical studies showed that an epoxy composition containing 5% IPDI-PETA2-DDS improved the flexural strength by 34% and impact strength by 36.7%. Furthermore, adding 5% IPDI-PETA2-ED to the epoxy composition increased the flexural strength by 39.7%, to 197 MPa and the impact strength by 38.8% to 68 J/m. These results highlight the potential of curing agents containing multiple amines for improving the mechanical properties of epoxy resins.

Synthesis of polyfunctional amines as curing agents and its effect on mechanical property of epoxy polymers

Kim

Jeon

et al. 2023

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Synthesis and properties of bisphenol‐Z polycarbonate via melt transesterification

Han,

Zhang,

Long

et al. 2023

Polycarbonate (PC) is a thermoplastic engineering plastic with excellent properties, and its excellent dielectric properties have broad application prospects in the field of electronics. In this paper, bisphenol Z (BPZ) and diphenyl carbonate (DPC) are used as raw materials to synthesize special polycarbonate (BPZ‐PC) by melt transesterification. The effects of catalyst type, catalyst dosage, molar ratio of raw materials, transesterification reaction time and vacuum degree, polycondensation reaction temperature and time on the molecular weight of the product are investigated, and the optimal reaction conditions are obtained. The chemical structure of the product is verified by FTIR, 1H‐NMR and 13C‐NMR spectra tests. The thermal properties, mechanical properties, optical properties and dielectric properties of BPZ‐PC are evaluated. Therefore, due to its excellent performance, BPZ‐PC, a high‐performance low‐dielectric polycarbonate, can be widely used in high‐frequency communication, microelectronics, and aerospace industries.

Polyurethane‐based cross‐linked nano spheres and their application in toughening epoxy resin

Shi,

Li,

Song

et al. 2024

Toughening thermo‐setting resins with both high impact strength and tensile strength is a challenging issue. In this study, a novel cross‐linked polyurethane nano spheres for toughening epoxy resin were prepared by self‐emulsification method with hexamethylene diisocyanate trimer (HDI trimer) and diethylene triamine (DETA) as the crosslinkers. The structure, morphology and particle size of cross‐linked polyurethane nano spheres were investigated by infrared spectroscopy, laser particle size analyzer and scanning electron microscopy. Results showed that the prepared cross‐linked polyurethane nano spheres showed spherical shape and had the size in the range from 40 to 258 nm. The application of cross‐linked polyurethane nano spheres in toughing epoxy resin was investigated. The results showed that cross‐linked polyurethane nano spheres can be uniformly dispersed in epoxy resin and no obvious aggregation phenomenon was observed. And the tensile strength and impact strength of epoxy resin can be increased simultaneously when the cross‐linked polyurethane nano spheres were used in toughening epoxy resin. With the increase of the amount of polyurethane nano spheres in epoxy resin, both the tensile strength and impact strength of epoxy resin had the trend of first increase and then decrease. The amount of HDI trimer in the microspheres had a great impact on their toughening effect on epoxy resin. When the cross‐linked polyurethane nano spheres contained HDI trimer content of 12 wt% and the amount of the nano spheres in epoxy resin was 8 wt%, the impact strength of the epoxy resin can reach as high as 23 kJ/m2, which was 4.33 times that of pristine epoxy resin. And the tensile strength of toughened epoxy resin was 50.7 MPa, which was at same level of that of pristine epoxy resin. The results of this study indicate that the cross‐linked polyurethane nano spheres have a great potential in toughening thermo setting resins, such as epoxy resin.