Rheological, crystal structure, barrier, and mechanical properties of PA6 and MXD6 nanocomposite films

Abstract

In this study, rheological, crystal structure, barrier, and mechanical properties of polyamide 6 (PA6), poly(m‐xylene adipamide) (MXD6) and their in situ polymerized nanocomposites with 4 wt % clay were studied. The extent of intercalation and exfoliation as well as type of crystals, crystallinity, and thermal transitions were investigated using X‐ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. Dynamic rheological measurements revealed that incorporation of nanoclay significantly increases complex viscosity of MXD6 nanocomposites at low frequencies, which was related to the formation of a nanoclay network and exchange reaction between MXD6 chains. The comparative study of dynamic characteristics (G′ (ω) and G″ (ω)) for aliphatic and aromatic polyamide nanocomposites with their neat resins as well as the relaxation spectra for both polymer systems confirmed the possibility of the aforementioned phenomena. Although, the crystallinity of MXD6 films was lower as compared to PA6 films, the permeability to oxygen was more than 5 times better for the former. Incorporating 4 wt% clay enhanced the barrier property, tensile modulus, and yield stress of PA6 and MXD6 nanocomposite films in both machine and transverse directions without sacrificing much puncture and tear resistances. The PA6‐based films showed higher tear and puncture strength as compared to MXD6 films. POLYM. ENG. SCI., 54:2617–2631, 2014. © 2013 Society of Plastics Engineers

Effect of uniaxial stretching on thermal, oxygen barrier, and mechanical properties of polyamide 6 and poly(m‐xylene adipamide) nanocomposite films

“…In our previous study , a cold crystallization exothermic peak in the first heating scan of precursor MXD6 and MXD6/clay was observed in the range of 104–134°C and 97–131°C respectively, which is in a good agreement with the results reported in other studies . The cold crystallization exothermic peaks of the uniaxially stretched MXD6 and MXD6/clay films are depicted in Fig.…”

“…Moreover, incorporating clay in the PA6 and MXD6 improves the oxygen barrier by ca. 40%, which was also discussed extensively in a previous study . The precursor MXD6/clay (DR = 1) shows significantly better barrier property, which is attributed to its lower free volume and more packed chains compared to the PA6/clay film .…”

“…The wide diffraction peak between 2 θ = 15 and 25° with a maximum intensity at 20.7° is related to the amorphous phase of the MXD6. The precursor and stretched MXD6/clay films reveal almost the same diffraction peak and a very little crystallinity due to high rigidity and low relaxation rate of the aromatic chains .…”

“…), however, the barrier and mechanical properties of the MXD6 films are better than those of the PA6. As discussed above, this could be explained by more rigidity and packing of the aromatic chains of the MXD6 compared with the PA6. A larger increase in the Young's modulus upon uniaxial stretching of the aliphatic nylons compared with that of the aromatic nylon films could also be interpreted to the higher level of crystallinity (Fig.…”

Influence of high pressures on CH4, CO2 and H2S solubility in polyethylene: Experimental and molecular simulation approaches for pure gas and gas mixtures. Modelling of the sorption isotherms

“…Thermoplastic polymers (TP) with good barrier and mechanical properties are of great interest for a wide range of applications going from packaging to energy production and distribution [1][2][3][4]. Among the large range of TP families, considerable attention has been paid on polyolefin family and more specifically on polyethylene.…”