Synthesis and characterization of amino-terminated hyperbranched polymer and its effect on impact resistance of epoxy resin thermosets

Abstract

Amino-terminated hyperbranched polymer (HBP-NH 2 ) was synthesized from diethylenetriamine (DETA) and methyl acrylate (MA) by melt polycondensation through AB 3 and AB 2 route, and its chemical structure was characterized by attenuated total internal reflectance infrared spectroscopy (ATR-IR) and 1 H nuclear magnetic resonance ( 1 H-NMR) spectroscopy. Then, the influence of HBP-NH 2 content on the toughness improvement and fractural surface morphology of diglycidyl ether of bisphenol A (DGEBA) cured systems was investigated through impact resistance test and field emission scanning electron microscopy (FESEM), respectively. The results indicated that HBP-NH 2 can enhance the toughness of epoxy cured system near 61 % than the neat DGEBA cured thermosets. FESEM images show that the toughness enhancement of epoxy system should be based on shearing deformation mechanism (the thermosets modified with low content of HBP-NH 2 ) and the second phase toughening mechanism (the thermosets modified with high content of HBP-NH 2 ).

Synergetic reinforcements of epoxy composites with glass fibers and hyperbranched polymers

“…The hyperbranched polymer with amino terminal groups, HBPA, was synthesized by condensation polymerization of AB 2 ‐type monomers, details of which have been described elsewhere . Briefly, 52 mL of methyl acrylate were blended with 43 mL of diethylenetriamine in 100 mL of methanol for 6 h in an ice‐water bath.…”

“…the compact shape and decreased interchain entanglements . Moreover, another advantage of HBPs is that HBPs possess numerous terminal reactive groups in their framework, such as hydroxyl , epoxide , or amino , which shows excellent functionality and leads to exceptional compatibility and interaction between HBPs and other polymer matrix . Besides, HBPs have a lot amount of free volumes and free spaces (intramolecular topological cavities) in their structures and thus can improve the impact resistance of thermosetting polymers .…”

“…Moreover, the unique globular structures can reduce the shrinkage of some thermosetting polymers, especially epoxy resins, due to the compact architecture stretching when their terminal groups interact with other functional groups of polymer matrix . Because of these favorable characteristics, hyperbranched polymers are widely used as modifiers for epoxy resins . However, the introduction of HBPs into epoxy composites may affect several mechanical properties, such as tensile strength and modulus, stiffness, and flexural strength and modulus owing to the introduction of flexible chains, which are contained in the architecture of HBPs .…”

Synthesis and curing properties of castor oil‐based triglycidyl ether epoxy resin

“…Epoxy resins are a class of polymers that form networks through curing reactions， which are widely used in adhesives, paint, coatings, composites, electrical insulators and electronic encapsulation materials. Compared with most thermoplastics, epoxy resins have higher strength, stiffness, heat resistance solvent resistance, and low shrinkage 1‐6 . Although the epoxy resins have various excellent properties, due to the high cross‐linking density, the epoxy resins have the disadvantages of brittleness, poor impact resistance, and poor fatigue resistance 7,8 .…”

Improved mechanical properties of epoxy-based composites with hyperbranched polymer grafting glass-fiber

“…[35,36] However, only several reports focus on the treatment of fibers with hyperbranched polymer (HBP). [37][38][39][40][41][42][43][44][45] And very few works have been published so far on composites containing fibers modified with HBP.…”