الفهرس 
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Abstract
In spite of epoxy resins have wide applications in various industrial fields; some properties need further improvement to fulfill more demanding applications, especially for high impact resistance purposes. Toughness improvement of epoxy resins requires the marriage between hardness and flexibility. In order to achieve this target, three amino-terminated hyperbranched polymers (HBPs) were prepared and tested as toughening and co-curing agents for epoxy resins, especially for high impact resistance purposes, in presence of the nano-reinforcing organo-modified Montmorillonite clay filler (OMMT). The formation of the hyperbranched polymers is based on Michael addition reaction of poly( ethylene glycol) diacrylate (PEODA) to three different amino compounds namely, 1-(2-arninoethyl)¬piperazine (AP), N-methy-l,3-propanediamine (NP A) and tris-2-arninoethylamine (T AEA) to form the corresponding hyperbranched polymers poly(PEODA-AP) (H]), poly(PEODA-NP A) (H2), and poly(PEODA- TAEA) (H3), respectively. The chemical structure and molecular weight of the prepared HBPs was verified using various techniques as FT-IR, IH-NMR and GPC.
The obtained results showed that HI polymer has no significant effect in the improvement of toughness properties of the epoxy resin (Epon-828). Furthermore, HI polymer can be used as alternative of the commercial hardener (Anacamine) of epoxy resin.
On the other hand, hyperbranched polymers H2 and H3 have promising features for improvement of toughness properties of epoxy resin in combination with the main hardener (Ancamine) at low content (20wt.%). In addition, the incorporation of the organo-modified Montmorillonite clay (OMMT) as reinforcing filler at relatively low loading (1-2 wt.% of epoxy resin) lead to more enhancement of the toughness of epoxy resin. This can be attributed to the exfoliation of organoclay platelets and their homogeneous dispersion at low content (1-2 wt.% of epoxy resin), which was confirmed by XRD and TEM techniques.
However, H2 polymer imparts better toughening enhancement for epoxy resin at lower content (20wt. % of epoxy resin) than H3 polymer, which was used at 60 wt. %of epoxy resin. Furthermore, H2 polYmer has higher thermal stability than H3 polymer.
More interestingly, the use of hyperbranched polymers has positive environmental impact in reducing the content of the volatile commercial amine hardener (solvent soluble) required for curing of epoxy resin (from 60 to 20wt% of the neat epoxy resin), which means less pollution.
At the last, amino-terminated hyperbranched polYmers have dual property as toughening and co-curing agents for epoxy resins which may open the way for the use of epoxy resins in more industrial applications especially for high impact resistance purposes.