In this paper, we present experimental and finite element simulations for optimizing the biaxial stretching of thermoplastic polyurethane (TPU) films, demonstrating how key parameters (stretching temperature, stretch ratio, strain rate) determine their mechanical and functional properties. The results identify an optimal processing window (110°C and a 2.5 × 2.5 stretch ratio), yielding an elastic recovery of 89.2%, a 250% increase in strength, and a retained fracture elongation of 1000%. Finite element simulations reveal the deformation patterns, showing that the optimal conditions produce a uniform stress distribution (32.1 MPa), whereas over–stretching causes severe stress concentration (86.0 MPa) near the clamping roots, with fracture prediction errors below 8%. The process–structure–property relationship demonstrates that efficient molecular chain alignment leads to an entropy–driven elastic network. These results provide both general insights and practical guidance for developing high–performance TPU films for high–volume packaging applications.
HamidiMNAbdullahJMahmudAS, et al.Influence of thermoplastic polyurethane (TPU) and printing parameters on the thermal and mechanical performance of polylactic acid (PLA)/Thermoplastic polyurethane (TPU) polymer. Polym Test2025; 143: 108697. https://doi.org/10.1016/j.polymertesting.2025.108697
3.
JiangJLiuFYangX, et al.Evolution of ordered structure of TPU in high–elastic state and their influences on the autoclave foaming of TPU and inter–bead bonding of expanded TPU beads. Polymer2021; 228: 123872. https://doi.org/10.1016/j.polymer.2021.123872
4.
LiBLiaoGLiY, et al.Investigation on the correlation between biaxial stretching process and macroscopic properties of BOPA6 film. Polymers2024; 16: 961. https://doi.org/10.3390/polym16070961
5.
LiuJLiaoGXieZ, et al.Investigation on the rheological behavior of PA6 film during biaxial stretching. Mater Today Commun2024; 38: 107616. https://doi.org/10.1016/j.mtcomm.2023.107616
6.
TangHHeJHaoL, et al.Developing nanofiltration membrane based on microporous poly (tetrafluoroethylene) substrates by bi–stretching process. J Membr Sci2017; 524: 612–622. https://doi.org/10.1016/j.memsci.2016.11.030
7.
QueY–HShiYLiuL–Z, et al.The crystallisation, microphase separation and mechanical properties of the mixture of ether–based TPU with different ester–based TPUs. Polymers2021; 13: 3475. https://doi.org/10.3390/polym13203475
8.
KimJ–HLeeT–IShinJ–W, et al.Bending properties of anisotropic conductive films assembled chip–in–flex packages for wearable electronics applications. IEEE Trans Compon Packag Manuf Technol2016; 6: 208–215. https://doi.org/10.1109/TCPMT.2015.2513062
9.
LiHMaYHuangY. Material innovation and mechanics design for substrates and encapsulation of flexible electronics: a review. Mater Horiz2021; 8: 383–400. https://doi.org/10.1039/D0MH00483A
10.
HeJChenJLiuJ, et al.Bone tissue engineering scaffold film with controlled release of tea polyphenol–magnesium nanoformulations to prevent bacterial infection. ACS Appl Polym Mater2024; 6: 12186–12196. https://doi.org/10.1021/acsapm.4c02251
11.
SafonovaLBobrovaMEfimovA, et al.A comparative analysis of the structure and biological properties of films and microfibrous scaffolds based on silk fibroin. Pharmaceutics2021; 13: 1561. https://doi.org/10.3390/pharmaceutics13101561
12.
DziadowiecDMatykiewiczDSzostakM, et al.Overview of the cast polyolefin film extrusion technology for multi–layer packaging applications. Materials2023; 16: 1071. https://doi.org/10.3390/ma16031071
13.
SitisanKSukthavornKNootsuwanN, et al.Development of dielectric biocomposite and biaxially oriented films from poly (lactic acid) and nano–silver coated microcrystalline cellulose. J Polym Environ2024; 32: 4889–4900. https://doi.org/10.1007/s10924–024–03222–8
14.
XieZLiaoGLiuJ, et al.Relaxation behavior of biaxially stretched PLA film during the heat setting stage. Front Mater2023; 10: 1241104. https://doi.org/10.3389/fmats.2023.1241104
15.
RadtkeLTorreMHughesTJ, et al.An analysis of high order FEM and IGA for explicit dynamics: mass lumping and immersed boundaries. Int J Numer Methods Eng2024; 125: e7499. https://doi.org/10.1002/nme.7499
16.
XuKChenWLiuL, et al.Numerical implementation, comparison and validation of a pressure dependent model for polymer composites. Int J Mech Sci2021; 212: 106818. https://doi.org/10.1016/j.ijmecsci.2021.106818
17.
ElyasiNTaheriKKNarooeiK, et al.A study of hyperelastic models for predicting the mechanical behavior of extensor apparatus. Biomech Model Mechanobiol2017; 16: 1077–1093. https://doi.org/10.1007/s10237–017–0874–x
18.
EsmailJFMohamedmekiMZAjeelAE. Using the uniaxial tension test to satisfy the hyperelastic material simulation in ABAQUS. IOP conference series: materials science and engineering, December 1, 2016, p. 012065: IOP Publishing. https://doi.org/10.1088/1757–899X/888/1/012065
19.
MachadoMCakmakUDKallaiI, et al.Thermomechanical viscoelastic analysis of woven–reinforced thermoplastic–matrix composites. Compos Struct2016; 157: 256–264. https://doi.org/10.1016/j.compstruct.2016.08.041
20.
FanXZhangWWangT, et al.Investigation on periodic cracking of elastic film/substrate system by the extended finite element method. Appl Surf Sci2011; 257: 6718–6724. https://doi.org/10.1016/j.apsusc.2011.02.111
21.
MuYHangLZhaoG, et al.Modeling and simulation for the investigation of polymer film casting process using finite element method. Math Comput Simulat2020; 169: 88–102. https://doi.org/10.1016/j.matcom.2019.09.012
22.
WangKZhangFBordiaRK. FEM modeling of in–plane stress distribution in thick brittle coatings/films on ductile substrates subjected to tensile stress to determine interfacial strength. Materials2018; 11: 497. https://doi.org/10.3390/ma11040497
23.
ZhongYTranLQNKureemunU, et al.Prediction of the mechanical behavior of flax polypropylene composites based on multi–scale finite element analysis. J Mater Sci2017; 52: 4957–4967. https://doi.org/10.1007/s10853–017–1568–6
24.
ZhanHChengWLiuF, et al.Resilient and robust mechanoresponsive polydimethylsiloxane/SiO2 composites induced by interfacial enhancement. J Colloid Interface Sci2025; 690: 137361. https://doi.org/10.1016/j.jcis.2025.137361
25.
JhangJ–CKaoHLinJ–H, et al.Composite planks consisting of high resilience buffer nonwoven fabrics and conductive elastic polymer films via hot pressing lamination: manufacturing techniques and mechanical, buffer, and electrical properties. Fibers Polym2023; 24: 1781–1788. https://doi.org/10.1007/s12221–023–00053–7
26.
OnonokponoOESpringM. The influence of binder film thickness on the mechanical properties of binder films in tension. J Pharm Pharmacol1988; 40: 126–128. https://doi.org/10.1111/j.2042–7158.1988.tb05195.x
27.
SerranoIGPandaJEdvinssonT, et al.Flexible transparent graphene laminates via direct lamination of graphene onto polyethylene naphthalate substrates. Nanoscale Adv2020; 2: 3156–3163. https://doi.org/10.1039/D0NA00046A
28.
BlanchardAGouanvéFEspucheE. Effect of humidity on mechanical, thermal and barrier properties of EVOH films. J Membr Sci2017; 540: 1–9. https://doi.org/10.1016/j.memsci.2017.06.031
29.
TavaresKMde CamposALuchesiBR, et al.Effect of carboxymethyl cellulose concentration on mechanical and water vapor barrier properties of corn starch films. Carbohydr Polym2020; 246: 116521. https://doi.org/10.1016/j.carbpol.2020.116521
30.
GielVKredatusováJTrchováM, et al.Polyaniline/Polybenzimidazole blends: characterisation of its physico–chemical properties and gas separation behaviour. Eur Polym J2016; 77: 98–113. https://doi.org/10.1016/j.eurpolymj.2016.02.008
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