Thermoplastic poly urethane (TPU) is a diblock copolymer which naturally phase segregates into thermodynamically incompatible hard (H) and soft (S) segments. The size of the segments and their spatial distribution can significantly affect the microstructure and mechanical properties of the material. In this paper, we investigated the effect of duration of exposure to ultrasound on the solution prior to film formation on the final film properties. The response variable for the study was primarily mechanical properties of the TPU thin films fabricated via a solution route utilizing tetra hydro furan as a solvent. The times of sonication were varied between 30 min and 90 min, while all films were fabricated at average thickness of 20 ± 5 μm. The mechanical tests have been conducted at two different displacement rates of 5 and 10 mm/min. Our results indicated that (relative to untreated TPU) ultrasound tends not to deteriorate the fracture strength, strain and yet improve the fracture toughness. We attribute these results to subtle events at the H and S segment/domain levels. To further understand these microstructural variations, we conducted differential scanning calorimetry scan tests between 25 °C and 200 °C at 5 °C/min on untested and tested TPU samples of all types. This data showed a delicate sonication time dependent trend and has been interpreted in conjunction with our mechanical test data. Transition temperatures, enthalpies, and specific heat capacities have been computed for these cases.

References

References
1.
Harrell.
,
L. L.
, Jr.
, 1969, “
Segmented Polyurethans. Properties as a Function of Segment Size and Distribution
,”
Macromolecules
,
2
(
6
), pp.
607
612
.
2.
Miller
,
J. A.
,
Lin
,
S. B.
,
Hwang
,
K. K. S.
,
Wu.
,
K. S.
,
Gibson
,
P. E.
, and
Cooper
,
S. L.
,
, 1983, “
Properties of Polyether-Polyurethane Block Copolymers: Effects of Hard Segment Length Distribution
,”
Macromolecules
,
18
, pp.
32
44
.
3.
Yamaski
,
S.
,
Nishiguchi
,
D.
, and
Kojio
,
K.
, 2007, “
Effects of Aggregation Structure on Rheological Properties of Thermoplastic Polyurethanes
,”
Polymer
,
48
, pp.
4793
4803
.
4.
Finnigan
,
B.
,
Martin
,
D.
,
Halley
,
P.
,
Truss
,
R.
, and
Campbell
,
K.
, 2004, “
Morphology and Properties of Thermoplastic Polyurethane Nanocomposites Incorporating Hydrophilic Layered Silicates
,”
Polymer
,
45
, pp.
2249
2260
.
5.
Harsanyi
,
G.
, 2000, “
Polymer Films in Sensor Applications: A Review of Present Uses and Future Possibilities
,”
Sens. Rev.
,
20
(
2
), pp.
98
105
.
6.
Tipple
,
C. A.
,
,
Lavrik
,
N. V.
,
,
Culha
,
M.
,
Headrick
,
J.
,
Datskos
,
P.
, and
Sepniak
,
M. J.
,
, 2002, “
Nanostructured Microcantilevers With Functionalized Cyclodextrin Receptor Phases: Self-Assembled Monolayers and Vapor Deposited Films
,”
Anal. Chem.
,
74
, pp.
3118
3126
.
7.
Sadaoka
,
Y.
,
Sakai
,
Y.
, and
Wang
,
X.
, 1994, “
Optical Properties of Fluorescent Dye-Doped-Polymer Thin Film and its Application to an Optochemical Sensor for Quantification of Atmospheric Humidity
,”
J. Mater. Sci.
,
29
, pp.
883
886
.
8.
Sohling
,
U.
,
Jung
,
G.
,
Saenger
,
D. U.
,
,
Lu
,
S.
,
Kutsch
,
B.
, and
Mennig
,
M.
, 1998, “
Synthesis and Optical Properties of Mn2+-Doped ZnS Nanoparticles in Solutions and Coatings
,”
J. Sol-Gel Sci. Technol.
,
13
, pp.
685
689
.
9.
Grant
,
P.
, S., and
McShane
,
M. J.
,
, 2003, “
Development of Multilayer Fluorescent Thin Film Chemical Sensors Using Electrostatic Self-Assembly
,”
IEEE Sens. J.
,
3
(
2
), pp.
139
145
.
10.
Wang
,
J.
, and
Swain
,
G. M.
,
, 2003, “
Fabrication and Evaluation of Platinum/Diamond Composite Electrodes for Electrocatalysis
,”
J. Electrochem. Soc.
,
150
(
1
), pp.
E24
E32
.
11.
Saenger
,
D. U.
,
Jung
,
G.
, and
Menning
,
M.
, 1998, “
Optical and Structural Properties of Doped ZnS Nanoparticles Produced by Sol-Gel Method
,”
J. Sol-Gel Sci. Technol.
,
13
, pp.
635
639
.
12.
Diaconu
,
I.
,
Dorhoi
,
D.-O.
, and
Ciobanu
,
C.
, 2006, “
Electromechanical Response of Polyurethane Films With Different Thickness
,”
Rom. J. Phys.
,
53
(
1–2
), pp.
91
97
.
13.
Leiby
,
M. W.
, “
Chemical Vapor Deposition by Pulsed Ultrasonic Direct Injection of Liquid Precursors Produces Verstaile Method For Creation of Thin Film Circuits and Devices
,” Application Note, SonoTek Corporation, 2012 Route 9W, Milton, NY 12547.
14.
Berger
,
H. L.
, 2006, “
Coating Drug-Eluting Arterial Stents Using Ultrasonic Spray Nozzles
,”
ILASS, 19th Annual Conference on Liquid Atomization and Spray Systems
,
Toronto
,
Canada
.
15.
Material Data Sheet/Processing Information, 2008, Lubrizol Advanced Materials, 29400 Lakeland Boulevard, Wickliffe, Ohio 44092.
16.
ASTM-D882-09, 2009, “
Standard Test Method for Thin Plastic Sheeting
,” pp.
1
10
.
17.
Yaws
,
C.
, L.,
Narasimhan
,
P. K.
,
, and
Gabbula
,
C.
, 2009,
Yaws’ Handbook of Antoine Coefficients for Vapor Pressure
,
2nd ed.
(
Electronic Edition), Knovel
,
New York
.
18.
Kimoto
,
H.
,
Ito
,
T.
, and
Tatsuzo
,
H.
, 1978, “
Ultrasonic Atomization of Some Polymer Solutions
,”
Acoust. Soc. Jap.
,
34
(
12
), pp.
721
723
.
19.
Chen
,
J.
,
Chen
,
Y.
,
Li
,
H
,
Lai
,
S.-Y.
, and
Jow
,
J.
, 2010, “
Physical and Chemical Effects of Ultrasound Vibration on Polymer Melt in Extrusion
,”
J. Appl. Polym. Sci.
,
17
, pp.
66
71
.
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