The effects of material formulation and manufacturing process on mechanical and thermal properties of epoxy/clay nanocomposites

Abstract

A holistic study was conducted to investigate the combined effect of three different pre-mixing processes, namely mechanical mixing, ultrasonication and centrifugation, on mechanical and thermal properties of epoxy/clay nanocomposites reinforced with different platelet-like montmorillonite (MMT) clays (Cloisite Na + , Cloisite 10A, Cloisite 15 or Cloisite 93A) at clay contents of 3-10 wt%. Furthermore, the effect of combined pre-mixing processes and material formulation on clay dispersion and corresponding material properties of resulting composites was investigated using X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), flexural and Charpy impact tests, Rockwell hardness tests and differential scanning calorimetry (DSC). A high level of clay agglomeration and partially intercalated/exfoliated clay structures were observed regardless of clay type and content. Epoxy/clay nanocomposites demonstrate an overall noticeable improvement of up to 10 % in the glass transition temperature (T g ) compared to that of neat epoxy, which is interpreted by the inclusion of MMT clays acting as rigid fillers to restrict the chain mobility of epoxy matrices. The impact strength of epoxy/clay nanocomposites was also found to increase by up to 24 % with the addition of 3 wt% Cloisite Na + clays. However, their flexural strength and hardness diminished when compared to those of neat epoxy, arising from several effects including clay agglomeration, widely distributed microvoids and microcracks as well as weak interfacial bonding between clay particles and epoxy matrices, as confirmed from TEM and SEM results. Overall, it is suggested that an improved technique should be used for the combination of pre-mixing processes in order to achieve the optimal manufacturing condition of uniform clay dispersion and minimal void contents.

Fused Deposition Modeling of Poly (Lactic Acid)/Walnut Shell Biocomposite Filaments—Surface Treatment and Properties

“…Many chemical treatment methods have been reported in prior literatures, such as alkali [4], silane coupling [13], maleation [14], and so on. Beyond that, some agents have also been used to improve the interfacial compatibility, such as montmorillonite [15], metakaolin [16], and talc [17].…”

Health and Safety Concerns Related to CNT and Graphene Products, and Related Composites

“…The chemical approach includes: (1) the creation of non-covalent bonding by the solvent and surfactant-assisted dispersion, and (2) the creation of covalent bonding by the surface functionalization of the nanomaterials. While the mechanical approach mainly employs the sophisticated mixing methods (Figure 3), such as: (1) dispersing the particles into the matrix with the help of sonication and or (2) by high shear mixing (three-roll milling) [25][26][27][28][29][30]. Melt-mixing routes are commonly used to prepare CNT-polymer and graphene-polymer nanocomposites within the thermoplastics industry, making them available at large scale.…”

Effect of Pickering emulsion on the mechanical performances and fracture toughness of epoxy composites

“…However, the physic‐mechanical performances of the nanocomposites composites have been greatly dependent on the degree of dispersion of nanomaterials in a polymer matrix . Many methods have been explored for promoting the dispersion of nanomaterials, such as grafting of functional polymers, ultrasonic treatment, shear mixing, and centrifugation . Although the dispersion of nanocomposites in a polymer matrix has been improved and the properties, especially the thermomechanical properties, have been promoted, the effects of nanocomposites on the properties of composites do not achieve the expectations.…”