Study on the Influence of Melt Processing on Segmented Polyurethanes Morphology

Frick, Achim; Mikoszek, Marzena

doi:10.1002/masy.201050809

Cited by 5 publications

(5 citation statements)

References 7 publications

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“…We combine well-known analysis methods that are founded in theory, in order to both avoid systematic errors of heuristic methods, and to attain an almost model-independent view on the structure evolution from the recorded sequences of scattering patterns. In doing so, the focus is on the still little investigated [2][3][4][5] effect of processing conditions on the structure and the properties of the material.…”

Section: Tensile Testsmentioning

confidence: 99%

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Structure and Mechanical Properties of an Injection‐Molded Thermoplastic Polyurethane as a Function of Melt Temperature

Stribeck

Zeinolebadi

Sari

et al. 2011

Macro Chemistry & Physics

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Thermoplastic polyurethanes (TPUs) molded at 205, 215, and 235 ° C are monitored by SAXS and WAXS during straining. A non-affi ne nanostructure deformation and related evolution mechanisms are found. DSC and microscopy are applied. DSC shows two melting endotherms. The results indicate that melts kept below the second peak stay phase-separated. The orientation parameter f ( ε ) and d f /d ε from WAXS are related to chain orientation mechanisms (strain ε ). SAXS shows hard domains that are only correlated to a next neighbor ("sandwich"). Thick sandwiches lengthen more than thin ones. Thin-layer sandwiches feature a strain limit. Some are converted into thick-layer sandwiches. Two materials have tough hard domains. Material processed at 235 ° C is soft and contains weak hard domains that fail for ε > 0.75. of the material. Block copolymers synthesized by living polymerization are characterized by uniform block lengths. Processing of such compounds may result in lattice-like nanostructures or even in photonic crystals, in which the soft and the hard blocks reside completely in different domains. This is different with thermoplastic polyurethanes (TPU). Along with their chains a mixed sequence of soft segments and hard segments is found. Thus, even optimum process control only leads to domains of very diverse shape and size, the arrangement of which can rarely lead to lattice-like correlation. Moreover, soft domains may contain several hard segments. Consequently, the chemistry [ 1 ] and the processing conditions [2][3][4][5] defi ne the nanostructure that, in turn, determines the material's mechanical properties. The hard domains form physical cross-links and make the material behave rubber elastic. Because the hard domains are permanent only to a fi rst approximation, the stressstrain behavior of TPUs is subject to "strong hysteresis, time dependence and cyclic softening". [ 6 ] Thus maturing or aging may become a problem, if longer time elapses between investigations with different methods, because in this case the results may not be combined.

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Section: Tensile Testsmentioning

confidence: 99%

“…Moreover, soft domains may contain several hard segments. Consequently, the chemistry [ 1 ] and the processing conditions [2][3][4][5] defi ne the nanostructure that, in turn, determines the material's mechanical properties. The hard domains form physical cross-links and make the material behave rubber elastic.…”

mentioning

confidence: 99%

Structure and Mechanical Properties of an Injection‐Molded Thermoplastic Polyurethane as a Function of Melt Temperature

Stribeck

Zeinolebadi

Sari

et al. 2011

Macro Chemistry & Physics

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“…Due to the poor compatibility of the soft and hard segments and the crystallization of the segments, the TPU block copolymers are separated into microphases or domains. In addition to the polymerization process, the processing also has a significant influence on the microstructure of the TPU, in turn, affects its mechanical properties …”

Section: Introductionmentioning

confidence: 99%

Microstructure and tensile properties of injection molded thermoplastic polyurethane with different melt temperatures

Xiang

Zhang

Zheng

et al. 2020

J of Applied Polymer Sci

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The use of injection molding technology to prepare heterogeneous interlayer film of laminated glass holds strong applicable potential. This article aims to investigate the effects of melt temperature and melt flow on the microstructure evolution and tensile properties of thermoplastic polyurethane (TPU) specimens during the injection molding process. The tensile properties of the TPU specimens show dependency on the melt temperature and melt flow direction. The results of birefringence indicate that melt flow and lower melt temperature induce higher stretching deformation of the molecular chain network. Small-angle X-ray scattering analysis approves that besides the melt temperature and flow direction, the testing position on the cross section of the specimen has great influence on the microstructure of the TPU sheet. Further analysis and conclusions can be made using wide-angle X-ray scattering method. The above results demonstrate that both the tensile properties and microstructure of the injection molded TPU specimens tend to be isotropic with the increase of melt temperature.

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“…Thermoplastic polyurethanes (TPU) are an important class of elastomeric materials present in sealing technology1 due to high elasticity at low temperatures and superior mechanical, tribological as well as chemical performance.…”

Section: Introductionmentioning

confidence: 99%

Process Induced Micro Structure Evolution in Polyester Polyurethane and Mechanical Properties Relationship

Frick

Mikoszek

2012

Macromolecular Symposia

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Summary: MDI‐HQEE‐Capa based thermoplastic polyurethane (TPU) with Shore hardness of 94 A was injection molded. In order to study the influence of melt conditions on the material structure evolution and resulting mechanical properties a systematical variation in processing temperatures in the range between 195 °C and 250 °C was applied. The mold temperature was kept constant at 60 °C. Process induced samples morphologies were investigated by means of light microscope (LM), scanning electron microscope (SEM) and differential scanning calorimeter (DSC). Mechanical visco‐elastic properties were determined by means of cyclic tensile experiment and were correlated with results of structural investigations. The evaluation of morphology micrographs of raw TPU material and specimens molded at different temperatures shows a reduction in visual crystalline fraction. This gains a distinct change in the deformation behavior of injection molded TPU with increasing melt processing temperature.

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Study on the Influence of Melt Processing on Segmented Polyurethanes Morphology

Cited by 5 publications

References 7 publications

Structure and Mechanical Properties of an Injection‐Molded Thermoplastic Polyurethane as a Function of Melt Temperature

Structure and Mechanical Properties of an Injection‐Molded Thermoplastic Polyurethane as a Function of Melt Temperature

Microstructure and tensile properties of injection molded thermoplastic polyurethane with different melt temperatures

Process Induced Micro Structure Evolution in Polyester Polyurethane and Mechanical Properties Relationship

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