High‐Temperature Crystalline Phases in Nylon 6/Clay Nanocomposites

Liu, Xiaohui; Breen, Christopher

doi:10.1002/marc.200500143

Cited by 21 publications

(15 citation statements)

References 19 publications

(21 reference statements)

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“…It could be related to the fact that the clay platelets initiate a heterogeneous nucleation that leads to an increase in the crystallinity of the nanocomposite samples. In general, the crystallinity of nylon‐based nanocomposite is controlled by the type of nylon matrix, molecular weight, clay concentration, and level of clay exfoliation . The crystallinity of the PA6/clay film is in agreement with those reported by Fasihi et al .…”

Section: Resultssupporting

confidence: 89%

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

Fereydoon

Tabatabaei

Ajji

2014

Polymer Engineering & Sci

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In this study, the effect of uniaxial stretching on the thermal, oxygen barrier and mechanical properties of aliphatic polyamide 6 (PA6) and aromatic Poly(m‐xylene adipamide) (MXD6) nylon films as well as their in‐situ polymerized nanocomposites with 4 wt% clay were studied. Cast films were prepared by extrusion process and rapidly cooled using an air knife. The precursor films were uniaxially stretched at 110°C with draw ratios varying from 1.5 to 5. DSC results showed that the cold crystallization temperature (Tcc) of the uniaxially stretched MXD6 and MXD6/clay films drastically shifted to the lower temperatures when draw ratio increased. The aromatic nylon films had lower oxygen permeability than those of the aliphatic films, due to more rigidity and chain packing. However, the oxygen permeability of the stretched films increased with draw ratio (DR) up to a critical value for each sample, while further stretching resulted in a reduction in the oxygen permeation. This phenomenon was related to the changes in free volume upon uniaxial stretching. The ability of different geometrical models to describe the experimental relative permeability data was investigated. The Bharadwaj model that took into account clay orientation was the most successful one to predict the oxygen barrier characteristics of the stretched nanocomposites at high draw ratios. The Young's modulus and tensile strength of the aliphatic and aromatic nylons increased with uniaxial deformation, while the flexibility and elongation at break of the former decreased with increasing DR. A larger increase in the Young's modulus of the uniaxially stretched nanocomposite films compared with the neat samples was observed and could be related to the improvement in the clay orientation as well as a better alignment of the crystalline phase due to incorporating the clay platelets in the polymer matrix. In contrast, the flexibility of the stretched MXD6 improved remarkably (ca., 25 times) compared with the precursor film (DR = 1) when the draw ratio increased to 1.5. This could be related to the effect of hot stretching on the enhancement of polymer chains relaxation and mobility at low draw ratios. POLYM. ENG. SCI., 55:1113–1127, 2015. © 2014 Society of Plastics Engineers

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Section: Resultssupporting

confidence: 89%

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

Fereydoon

Tabatabaei

Ajji

2014

Polymer Engineering & Sci

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“…For annealed PA6 and PA6/clay films, in addition to the presence of sharp endothermic peaks at 220°C, which are due to the melting of α ‐form crystals, other small endothermic peaks are also detected at 175°C and 160°C, respectively. These additional peaks can be attributed to the formation of small crystals during annealing . They were also related by some authors to an enthalpy relaxation process of the interphase between the crystalline and amorphous phases, which can be induced by isothermal crystallization or annealing process.…”

Section: Resultsmentioning

confidence: 74%

“…The γ ‐phase has a pseudo hexagonal structure with the dimensions of a = 0.472, c = 1.688 nm, and γ = 120°, where the twisted chains allow formation of the hydrogen bonds between parallel chains . It has been shown that PA6 crystalline structure depends strongly on processing conditions . In general, lower temperature and faster cooling rate promote γ ‐crystal of PA6 while higher crystallization temperature and slow cooling rate create more α ‐crystal.…”

Section: Resultsmentioning

confidence: 99%

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

2013

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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

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“…To observe the effect of clay loading on mechanical properties of PCN, same polymer and organic modifier (12‐aminolauric acid) containing three different clay loading (3, 6, and 9 wt % of 12‐aminolauric acid based OMMT of the weight of polymer) are synthesized and their nanomechanical properties are evaluated in this work. X‐ray diffraction (XRD)54–65 and differential scanning calorimetry (DSC)66–76 are often used techniques to study the crystallinity of polymeric materials. In this work, the crystallinity of PCN is studied using XRD and DSC to evaluate the change in crystallinity of PCN with respect to pristine polymer and its effect on nanoscale property enhancement of PCN.…”

Section: Introductionmentioning

confidence: 99%

Effect of organic modifiers on dynamic and static nanomechanical properties and crystallinity of intercalated clay–polycaprolactam nanocomposites

Sikdar¹,

Katti²,

Katti³

et al. 2007

J of Applied Polymer Sci

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Polymer clay nanocomposites (PCN) of Polyamide6 and sodium montmorillonite are prepared using different organic modifiers (12-aminolauric acid, n-dodecylamine, and 1,12-diaminododecane) to study effect of organic modifiers on structure and nanomechanical properties of PCN. Using X-ray diffraction and differential scanning calorimetry, crystalline nature of PCNs are evaluated. Nanoscale viscoelastic properties of PCNs are evaluated using nanodynamic mechanical analyzer (NanoDMA). Nanoscale elastic modulus and hardness of PCNs are evaluated using nanoindenter. PCNs show enhancement in elastic modulus, storage modulus, loss modulus, and loss factor by maximum amount of 62.88%, 56.38%, 145.74%, and 71.43%, respectively, and decrease in percentage crystallinity by 16.52% compared to pure polymer. This result indicates that organic modifiers have effect on crystallinity and nanomechanical properties of PCN. To evaluate effect of clay loading on nanomechanical properties of PCN, PCN containing 12-aminolauric acid is synthesized with different weight percent (3, 6, and 9% of weight of polymer) of organically modified montmorillonite (OMMT), which shows that nanomechanical properties of PCN improves with increase in clay loading. Our study reveals that change in crystallinity of polymer in PCN may have role in the enhancement of nanomechanical properties of PCNs in comparison to pristine polymer.

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High‐Temperature Crystalline Phases in Nylon 6/Clay Nanocomposites

Cited by 21 publications

References 19 publications

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

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

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

Effect of organic modifiers on dynamic and static nanomechanical properties and crystallinity of intercalated clay–polycaprolactam nanocomposites

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