Morphology and Properties of Nylon 6 Blown Films Reinforced with Different weight percentage of Nanoclay additives

Raghavendra. R. Hegde, Gajanan S. Bhat , and Bhushan Deshpande b

The University of Tennessee, Knoxville TN 37996-2200, USA and

b Techmer PM, Clinton, TN 37716

WAXD pinhole pattern

2D WAXS pinhole patterns of films are shown in Figure S1. Patterns do not show significant change in orientation for any samples.

Figure S 1.2D WAXD pinhole patterns of films.

Non-isothermal crystallization kinetics of film samples

All the graphs of non-isothermal crystallization kinetics are included in supplementary information Figures S2 to S5 and Table S1. At lower cooling rate, crystallization starts at higher temperature because there is more time available to overcome nucleation barrier. With increase in cooling rate, the peak crystallization temperature shifts to lower temperature

Figure S 2. CN6F (control nylon 6 film).[Color figure can be viewed in the online issue]

Figure S 3. N6CF2.[Color figure can be viewed in the online issue]

Figure S 4. N6CF5.[Color figure can be viewed in the online issue]

Figure S 5. N6CF10.[Color figure can be viewed in the online issue]

Table S 1. The crystallization onset temperature (T onset) and peak crystallization temperature (T peak) for different film samples.

CN6F
Cooling rate (°C) / 5 / 10 / 20 / 50 / 65 / 85
onset (°C) / 194 / 194 / 191 / 187 / 177 / 139
peak (°C) / 175 / 169 / 168 / 160 / 123 / 95
t1/2 (sec) / 19 / 27 / 30 / 51 / 87 / 94
N6CF2
Cooling rate (°C) / 5 / 10 / 20 / 50 / 65 / 85
onset (°C) / 198 / 197 / 191 / 187 / 173 / 113
peak (°C) / 167 / 146 / 157 / 143 / 100 / 42
t1/2 (sec) / 18 / 19 / 24 / 33 / 36 / 96
N6CF5
Cooling rate (°C) / 5 / 10 / 20 / 50 / 65 / 85
onset (°C) / 196 / 193 / 189 / 181 / 141 / 114
peak (°C) / 182 / 171 / 168 / 147 / 96 / 42
t1/2 (sec) / 10 / 18 / 19 / 22 / 39 / 65
N6CF10
Cooling rate (°C) / 5 / 10 / 20 / 50 / 65 / 85
onset (°C) / 196 / 192 / 188 / 178 / 139 / 138
peak (°C) / 185 / 170 / 158 / 147 / 98 / 41
t1/2 (sec) / 19 / 19 / 27 / 46 / 63 / 64

Nanoindentation

Experiment involved following steps;

  1. Careful approach of indenter to surface
  2. Loading to peak load (mN)
  3. Holding of indenter at peak load
  4. Unloading 90% of peak load for 50’s
  5. Holding the indenter after 90% unloading for 100 s
  6. Completely unloading

As the indenter penetrates in to sample, both elastic and plastic deformations occur in the sample. Only elastic portion of displacement is recovered. Hardness (H) and elastic modulus (E) were calculated from load-displacement data as in Equation 1;

Equation 1

Where is the load measured at maximum depth at the point of penetration (h) during indentation, A-projected contact area (24.5 ) and hc is contact depth of indent. Elastic modulus of the sample can be inferred from the initial unloading contact stiffness (S), i.e., the slope of the initial portion of unloading curve. The relation between contact stiffness, contact area and elastic modulus are given by Equation 2;

Equation 2

Where β is a constant that depends on the geometry of the indenter (β=1.034 for Berkovich indenter) and Er is the reduced elastic modulus which accounts for the fact that elastic modulus occurs in both the sample and the indenter. The sample elastic modulus (Es) can be given as in Equation 3;

Equation 3

Where, vs and vi are the poissons ratios of specimen and indenter respectively, while Ei is the modulus of the Berkovich indenter (1141 Gpa) [[1]]. In this research, near surface hardness and elastic modulus of nylon 6-clay nanocomposites films were evaluated using the nanoindentation technique.

Nanoindentation experiment is carried out using Nanoindenter X.P MTS tester with berkovich hp tip, 2 nm continuous stiffness test. Indenter separated by 150μ , Strain rates covered were 0.02, 0.05, 0.1, 0.2 sec-1. Elastic modulus, Surface hardness and creep behavior of control nylon 6 films and nylon 6-nanoclay composite films were estimated using nanoindentation.

Figure S 6. (a) Hardness and (b) modulus profiles of nylon 6 blown films obtained from nanoindentation with different percentage of clay loading.[Color figure can be viewed in the online issue]

Table S 2. Results of nanoindentation.

Strain Rate (1/s) / 0.02(1/s)
Modulus From Unload / Hardness From Unload
Sample Name / GPa / Std. Dev. / % COV / GPa / Std. Dev. / % COV
CN6F / 1.86 / 0.05 / 2.59 / 0.09 / 0.00 / 3.22
N6CF2 / 2.55 / 0.05 / 2.09 / 0.12 / 0.00 / 3.12
N6CF5 / 3.11 / 0.36 / 45.79 / 0.12 / 0.02 / 14.61
N6CF10 / 3.23 / 0.07 / 91.32 / 0.128 / 0.005 / 4.06
Strain Rate (1/s) / 0.05(1/s)
CN6F / 1.95 / 0.04 / 2.25 / 0.10 / 0.00 / 3.78
N6CF2 / 2.57 / 0.00 / 0.16 / 0.13 / 0.00 / 1.51
N6CF5 / 3.01 / 0.43 / 43.15 / 0.15 / 0.04 / 24.36
N6CF10 / 3.23 / 1.77 / 91.32 / 0.15 / 0.01 / 3.86
Strain Rate (1/s) / 0.1(1/s)
CN6F / 2.02 / 0.04 / 1.77 / 0.11 / 0.01 / 4.45
N6CF2 / 2.45 / 0.05 / 2.12 / 0.13 / 0.01 / 3.59
N6CF5 / 3.09 / 0.34 / 42.01 / 0.17 / 0.03 / 17.99
N6CF10 / 3.06 / 0.66 / 54.18 / 0.17 / 0.06 / 36.24
Strain Rate (1/s) / 0.2(1/s)
CN6F / 1.89 / 0.07 / 3.60 / 0.11 / 0.01 / 5.09
N6CF2 / 2.41 / 0.01 / 0.24 / 0.14 / 0.00 / 0.04
N6CF5 / 2.89 / 0.20 / 6.91 / 0.14 / 0.02 / 11.82
N6CF10 / 3.13 / 0.37 / 11.71 / 0.18 / 0.03 / 14.45

Contact angle measurement

Wetting is the ability of a liquid to maintain contact with a solid surface and is crucial in the bonding or adherence of two materials. Cohesive force causes the liquid to retain its circular shape while, liquid drop spreads on the surface due to adhesive force between interface. Contact angle of drop of liquid on the solid is the angle at which the liquid–vapor interface meets the solid-liquid surface.

Degree of wetting (wettability) is determined by a force balance between adhesive and cohesive forces. Decrease in contact angle indicates the extent of liquid drop spreading on the solid surface. So contact angle measurements can be used as an indicator of ‘wettability’ of surfaces [[2]].

The contact angle determination of a liquid–solid–vapor system satisfies Young’s equation given by Equation 48. The equation is based on a 3-phase contact line, solid (s), liquid (l).

Equation 4

Where,

σs- Surface tension of solid,

σl- surface tension of liquid,

γsl -the interfacial tension between the solid and liquid phases,

θ-the contact angle corresponding to the angle between vectors σl and γsl [[3]].

References

Corresponding author;Gajanan Bhat, Professor, Department of Materials Science and Engineering205 TANDEC BUILDING, The University of Tennessee, Knoxville, TN 37996, Phone: 865-974-0976, Fax: 865-974-5236Email:

[1]. Phar G. Oliver WC, J Mater Res 1992; 7, 1564.

[2]. Sharfrin E., The Journal of Physical Chemistry 1960; 64, 519.

[3]. KRÜSS, Contact angle measurement – a theoretical approach; 2005.