Preparation and crystallization behavior of syndiotactic polystyrene–clay nanocomposites

Polymer Nanocomposites-A Comparison between Carbon Nanotubes, Graphene, and Clay as Nanofillers

Nanofilled polymeric matrices have demonstrated remarkable mechanical, electrical, and thermal properties. In this article we review the processing of carbon nanotube, graphene, and clay montmorillonite platelet as potential nanofillers to form nanocomposites. The various functionalization techniques of modifying the nanofillers to enable interaction with polymers are summarized. The importance of filler dispersion in the polymeric matrix is highlighted. Finally, the challenges and future outlook for nanofilled polymeric composites are presented.

Synthesis and characterization of 1, 1-bis (3-methyl-4-epoxyphenyl) cyclohexane-toughened DGEBA and TGDDM organo clay hybrid nanocomposites

1,1-bis (3-methyl-4-epoxyphenyl) cyclohexane (BMEPC) was synthesized from 1,1-bis (3-methyl-4-hydroxyphenyl) cyclohexane and 2-(chloromethyl) oxirane, and its structure was confirmed by Fourier transform infrared (FT-IR), 1H-, 13C-NMR and electron impact-mass spectrometry. Both diglycidyl ether of bisphenol-A (DGEBA) and tetraglycidyl diamine diphenyl methane (TGDDM) epoxy resins were toughened with BMEPC using 4,4′-diaminodiphenylmethane (DDM) as a curing agent. Epoxy and BMEPC-toughened epoxy systems were further modified with organophilic MMT (OMMT) clay. The chemical reactions involved between epoxy and DDM with OMMT was confirmed by FT-IR. OMMT clay-filled hybrid BMEPC-epoxy resin castings were characterized for their mechanical, thermal, thermo-mechanical and morphological properties. The values of Tg and heat distortion temperature of hybrid epoxy decreased with increasing incorporation of OMMT. The data obtained from thermal studies indicated that the incorporation of nano clay into BMEPC-modified hybrid systems possess improved thermal stability. The mechanical properties were studied as per ASTM standards. The TGDDM-based hybrid epoxy system exhibited higher values of tensile and flexural properties than that of the DGEBA hybrid epoxy system, whereas the impact strength of the DGEBA system was higher when compared with that of the TGDDM system. The values of dielectric constant (ϵ′) and dielectric loss (ϵ′′) were increased with increased incorporation of OMMT clay in both systems. From the X-ray diffraction analysis it was observed that the absence of d001 reflections in OMMT-filled BMEPC-modified epoxy systems indicated the formation of exfoliated nano hybrids. The homogenous morphologies were ascertained from scanning electron microscope and transmission electron microscope.

Studies on thermal, mechanical and morphological properties of organoclay filled azomethine modified epoxy nanocomposites

Inter cross-linked networks of organoclay-filled, azomethine-modified epoxy nanocomposites have been developed. Two types of azomethine epoxies (AE1 and AE2) incorporated into diglycidyl ether of bisphenol A (DGEBA) epoxy resin with varying percentages (5, 10 and 15%) were cured with diamine diphenyl methane (DDM). The azomethine epoxies were synthesized and characterized by Fourier transform infrared and 1H-NMR spectroscopy. The incorporation of azomethine epoxies into DGEBA epoxy resin improved both thermal and mechanical properties to an appreciable extent. The introduction of organoclay into DGEBA epoxy resin exhibited almost similar characteristics to that of the azomethine-modified DGEBA epoxy resin. Both azomethine epoxy and organoclay have been incorporated into DGEBA epoxy resin in order to improve the thermal and mechanical properties in comparing other modified epoxies. The glass transition temperature and thermal degradation temperature of azomethine-modified epoxies, organoclay-filled epoxy and organoclay-filled azomethine-modified DGEBA epoxies were determined by using differential scanning calorimeter and thermogravimetric analysis. The mechanical properties, namely the tensile strength, flexural strength and impact strength of the resultant nanocomposites were studied as per ASTM standards. X-ray diffraction studies of the cured nanocomposites indicate that the organophillic montmorillonite clay was exfoliated into the cured product. The homogeneous morphology of azomethine-modified DGEBA epoxy and organoclay-filled azomethine-modified epoxy were ascertained by scanning electron microscopy.