PA66/PA12/clay based nanocomposites: morphology and physical properties

Abstract

The structure and the physical properties of several polyamide 66 (PA66)/polyamide 12 (PA12) blends containing different amounts of the two polymers and obtained by melt‐blending have been investigated. A low amount of organically‐modified layered silicate (OMLS, 4 wt%) has also been introduced in order to further improve the physical properties and, in particular, to evaluate its effect on the blends' structure and components' miscibility. The microstructure and morphology of all the composites were analyzed by means of X‐Ray diffraction (WAXD), transmission electron microscopy (TEM), and high resolution scanning electron microscopy (SEM), while the macroscopic scale properties (mechanical behavior and water adsorption) were assessed in order to investigate and understand the materials' structure–properties relationships. The partial miscibility of PA66 and PA12, with phase separation depending on blend composition, has been confirmed. The results also underlined the possibility to tailor the behavior of polymer blends in terms of mechanical water adsorption properties by varying the amount of PA12, added to PA66 with and without the addition of the OLMS. The effectiveness of the clay in modifying the components' miscibility as well as its tendency to segregate preferentially within separate PA66 domains have been assessed. WAXD results showed opposite effects of PA12 and clay on the crystallization behavior of PA66, an aspect that has also been deepened in another paper by the same authors discussing the results of the complete thermal characterization. Copyright © 2010 John Wiley & Sons, Ltd.

Morphology and Thermal Properties of Compatibilized PA12/PP Blends with Boehmite Alumina Nanofiller Inclusions

“…It can be deduced from this figure, that the melting temperature, T m for the composites and the blend did not shift significantly from the bulk polymer's T m (PP = 163.5 °C, PA12 1 = 178.5 °C, and PA12 2 = 170.6 °C). The two peak melting points observed in N100 (PA12) are associated with predominant γ‐crystals and less dominant α‐crystals, which are peculiar to and well reported for PA12 16, 25, 34. This led to another important parameter that relates to the crystallization temperature and percentage crystallinity ( X c ).…”

“…X c for the PP and PA12 were estimated for each sample, using the expression34 where Δ H m, i indicates the specific melt crystallization enthalpy of the i ‐th components in the sample, w c, i is the weight fraction of the i ‐th component in the blend, $\Delta H_{{\rm m},i}^{{\rm o}} $ is the specific enthalpy of fusion of an ideal 100% crystalline i ‐th component based on literature data27 ($\Delta H_{{\rm m,pp}}^{{\rm 0}} $ = 209 J · g −1 and $\Delta H_{{\rm m,PA12}}^{0} $ = 95 J · g −1 ), and k , is calculated considering AlO(OH) weight percentage, i.e., 1 for neat polymers and polymer blend and 0.99 for 1 wt% composition of AlO(OH).…”

“…Figure 7(b), representing the tan δ (damping, E″ / E′ ) functions, N100 shows two relaxation peaks observed at around +60 and –60 °C, which are known as the α‐ and β‐relaxation peaks of PA12, respectively 34, 35. α‐relaxation peak is linked to the breakage of hydrogen bonds between the polymer chains, which induces long‐range segmental motion in the amorphous area, therefore this represents the T g of PA12.…”

“…A few authors 27, 36 have confirmed that the thermal decomposition of PP involves the random chain scission and intermolecular transfer involving tertiary hydrogen abstractions from the polymer by primary radical. Also, the thermal decomposition of polyamides is of three different mechanisms namely: free radical, cis‐ elimination, and an intermolecular exchange mechanism 27, 34. AlO(OH) usually undergoes a crystalline lattice phase change after 300 °C by dehydration.…”

Effect of zeolite 5A on compatibility and properties of linear low‐density polyethylene/thermoplastic starch blend

“…For the PE/TPS blend, the T g of TPS decreased to 47.4°C. With the addition of 1–5 wt % of zeolite, the T g of TPS in the PE/TPS blend decreased significantly ( P ≤ 0.05), by ∼ 3–4°C, possibly because the presence of zeolite 5A could increase the chain mobility of PE and TPS, as well as the miscibility between the two polymers 35. Endothermic transitions at temperatures of 121.2 and 169.2°C corresponded to T m s of neat PE and TPS, respectively.…”