View source for Instrumented Tensile Impact Test (ITIT), Examples

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<span style="font-size:1.2em;font-weight:bold;">Instrumented tensile impact test (ITIT), examples</span>
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==General==

The [[instrumented Tensile Impact Test (ITIT)|instrumented tensile-impact test (ITIT)]] is used for [[Plastics|plastics]] and [[Elastomers|elastomers]] to determine or optimise their [[Toughness|toughness]] [1, 2]. However, this method of [[Polymer Testing|polymer testing]] and [[Polymer Diagnostic|diagnostics]], which is relatively rarely described in the literature, can be advantageously applied to [[Specimen|test specimens]] of small thickness, e.g. those cut from thin-walled [[Plastic Component|plastic components]], but particularly to plastic films. The validity of the method and the experimental procedure [3] have been explained in detail under “[[Instrumented Tensile Impact Test (ITIT)|Instrumented tensile-impact test]]”.

The following examples demonstrate the suitability of the ITIT for investigating the influence of technological manufacturing parameters (e.g. rolling time) and formulation optimisation (e.g. sulphur and carbon black content in elastomers).

==Example 1: Influence of manufacturing conditions on the optimisation of the toughness of polyvinyl chloride==

As part of investigations into the optimisation of the toughness of impact-resistant PVC materials produced using roll-press technology, Hoffmann and Leps [4] evaluated the dependence on the technological parameter ‘rolling time’ using the ITIT ('''Fig. 1'''). To assess toughness, fracture toughness (see: [[Fracture Mechanics|fracture mechanics]]) was used as a [[Material Value|characteristic value]] in the [[Fracture Mechanical Testing|fracture mechanical tests]] ('''Eqs. (1)''' and '''(2)'''):

'''Dynamic stress intensity factor K<sub>Id</sub>'''

{|
|-
|width="20px"|
|width="500px"|<math>K_{Id}=\frac{F_{max}}{B \cdot W^{\frac{1}{2}}} \cdot f \left (\frac{a}{W}  \right )</math>
|(1)
|}

with:

{|
|-
|width="20px"|
|width="500px"|<math>f\left( \frac{a}{W} \right )=\frac{\sqrt{\frac{\pi a}{2W}}}{\sqrt{1-\frac{a}{W}}}\left [ 1.122-0.561\left ( \frac{a}{W} \right )-0.205\left ( \frac{a}{W} \right )^{2}+0.471 \left ( \frac{a}{W} \right )^{3}+0.190\left ( \frac{a}{W} \right )^{4} \right ]</math>
|(2)
|}

according to [5].

The two impact-resistant PVC materials each consist of 92 parts PVC and 8 parts modifier (EVA copolymer with 14 wt.-% VAC), with the PVC in composition 1 (K = 63) having the higher K-value (a measure of [[Viscosity|viscosity]]) compared with composition 2 (K = 60). The rolling temperature ''T''<sub>W</sub> was 170 °C.

[[File:ITIT-Ex_Fig1.jpg|500px]]
{| 
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px"|Toughness optimisation of two tough PVC materials – influence of the rolling time ''t''<sub>W</sub> in the roll-press process on the stress intensity factor ''K''<sub>Id</sub> at a rolling temperature of ''T''<sub>W</sub> = 170 °C
|}

For the dynamic stress intensity factor ''K''<sub>Id</sub>, a maximum [[Toughness|toughness]] was determined for both compositions of the impact-resistant PVC materials at rolling times of 15 to 20 minutes; this is based on a parallel increase and decrease in both the maximum fracture load ''F''<sub>max</sub> and the fracture time ''t''<sub>B</sub>, which also allows for an evaluation using the concept of [[Fracture Mechanics#Linear-elastic fracture mechanics|linear-elastic fracture mechanics]].

The higher toughness values of composition 1 at longer rolling times are attributed, in the morphological analyses in [4], to the partial preservation of the network structure typical of good toughness behaviour (a PVC globular framework permeated by the rubber network), as illustrated by an example in '''Fig. 2'''.

[[File:IKZV_Beispiele-2.jpg|400px]]
{| 
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px"|[[Transmission Electron Microscopy|Transmission electron microscopy (TEM)]] micrograph (stained [[Ultramicrotomy|ultra-thin section]]) of PVC-P, composition 1 roll time ''t''<sub>W</sub> = 15 min
|}

==Example 2: Formulation optimisation of styrene-butadiene rubber (SBR) vulcanisates with regard to toughness properties==

Reincke [6‒10] significantly expanded the scope of application of the ITIT as part of investigations into the relationship between compounding formulations, structure and fracture mechanical properties of [[Elastomers|elastomeric]] materials. To evaluate [[Toughness|toughness]], the ''J''<sub>Id</sub> value — determined according to the [[J-Integral Concept|J-integral concept]] — was used as a [[Material Value|characteristic value]] in [[Fracture Mechanical Testing|fracture mechanics testing]] ('''Eq. (3)''' and '''Eq. (4)''').

'''J-value ''J''<sub>Id</sub>'''

{|
|-
|width="20px"|
|width="500px"|<math>J_{Id}=\frac{\eta \cdot A_{max}}{B(W-a)}</math>
|(3)
|}

respectively for occurring crack propagation energy A<sub>p</sub>:

{|
|-
|width="20px"|
|width="500px"|<math>J_{Id}=\frac{\eta \cdot \left (A_{max}+A_{p} \right )}{B(W-a)}</math>
|(4)
|}

Studies on unfilled and filled styrene-butadiene rubber (SBR) vulcanisates are presented as examples [6, 9, 10].

[[Cross-linking Elastomers|Cross-linking]] was carried out using sulphur. By varying the sulphur content as the cross-linking agent, it is possible to alter the chain density of the network formed during [[Vulcanization|vulcanization]] and thus influence the properties of the elastomer. The filled SBR vulcanisates are vulcanisates with the same sulphur content but different proportions of the filler carbon black. '''Figure 3''' shows the J-values as a measure of resistance to unstable [[Crack Propagation|crack propagation]].

[[File:ITIT-Ex_Fig3.jpg|500px]]
{| 
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px"|Effect of carbon black and sulphur content on the J-values of elastomeric materials, determined in an instrumented tensile-impact test
|}

For the unfilled vulcanisates, the J-values determined show a steady decrease in [[Toughness|toughness]]. For the filled [[Vulcanization|vulcanisates]], a maximum is observed. This maximum [11‒13] indicates that the addition of filler only improves the toughness properties of the material system under consideration up to 40 phr of carbon black under the given test conditions.

==See also==

* [[Instrumented Tensile Impact Test (ITIT)|Instrumented tensile-impact test]]
* [[MPK-Procedure MPK-ITIT]]
* [[Instrumented Charpy Impact Test|Instrumented Charpy impact test]]
* [[Impact Loading Plastics|Impact loading plastics]]
* [[Tensile Impact Test|Tensile-impact Test]]
* [[Toughness]]

==References==

{|
|-valign="top"
|[1]
|[[Grellmann,_Wolfgang|Grellmann, W.]], [[Seidler, Sabine|Seidler, S.]] (Eds.): Polymer Testing. Carl Hanser, Munich (2022) 3rd Edition, pp. 272–275 (ISBN 978-1-56990-806-8; E-Book: ISBN 978-1-56990-807-5; see [[AMK-Library]] under A 22) 
|-valign="top"
|[2]
|[[Reincke,_Katrin|Reincke, K.]]: Bruchmechanische Bewertung von gefüllten und ungefüllten Elastomerwerkstoffe. Mensch & Buch Publishing, Berlin (2005), (ISBN 978-3-86664-021-4; see [[AMK-Library]] under B 1-13) 
|-valign="top"
|[3]
|[[MPK-Procedure MPK-ITIT|MPK-Procedure MPK-ITIT]] (2012-06): Testing of Plastics – Instrumented Tensile-Impact Test (ITIT): Procedure for Determining the Crack Resistance Behaviour Using the Instrumented Tensile-Impact Test
|-valign="top"
|[4]
|Hoffmann, H., Leps, G., [https://www.researchgate.net/profile/Wolfgang-Grellmann Grellmann, W.], Stephan, R., Hanisch, H.: Beurteilung der Zähigkeitseigenschaften von schlagzähem PVC. Plaste und Kautschuk 32 (1985) 379‒381 
|-valign="top"
|[5]
|Anderson, T. L.: Fracture Mechanics. Fundamentals and Applications. 3rd Ed, CRC Press Boca, Raton (2005) (ISBN 978-0849342608; see [[AMK-Library]] under E 8-2); [https://doi.org/10.1201/9781420058215 https://doi.org/10.1201/9781420058215]
|-valign="top"
|[6]
|Reincke, K.: Elastomere Werkstoffe – Zusammenhang zwischen Mischungsrezeptur, Struktur und mechanischen Eigenschaften sowie dem Deformations- und Bruchverhalten, Habilitation, Martin-Luther-Universität Halle-Wittenberg, Shaker Publishing (2016) (ISBN 978-3-8440-4637-3; see [[AMK-Library]] under B 2-2) 
|-valign="top"
|[7]
|Reincke, K., Grellmann, W.: Elastomers. Impact loading. In: [https://de.wikipedia.org/wiki/Wolfgang_Grellmann Grellmann, W.], [https://www.researchgate.net/profile/Sabine-Seidler Seidler, S.]: Mechanical and Thermomechanical Properties of polymers. Landolt-Börnstein. Volume VIII/6A3, Springer, Berlin (2014) pp. 502‒509, (ISBN 978-3-642-55165-9; see [[AMK-Library]] under A 16) 
|-valign="top"
|[8]
|Reincke, K., Grellmann, W.: Approaches to characterise the mechanical properties of films and elastomers. In: Grellmann, W., Langer, B.: Deformation and Fracture Behaviour of Polymer Materials. Springer Series in Materials Science 247, Springer, Berlin Heidelberg (2017) 225‒336 (ISBN 978-3-319-41877-3; e-Book: ISBN 978-3-319-41879-7; see [[AMK-Library]] under A 19) 
|-valign="top"
|[9]
|Grellmann, W., Reincke, K., [https://researchgate.net/profile/Ralf-Lach Lach, R.], Heinrich, G.: Characterization of crack toughness behaviour of unfilled and filled elastomers. Kautschuk, Gummi, Kunststoffe 54 (2001) 397‒402 [https://www.kgk-rubberpoint.de/wp-content/uploads/migrated/paid_content/artikel/117.pdf Download as pdf]; DOI: [https://doi.org/10.3139/120.100575 https://doi.org/10.3139/120.100575]
|-valign="top"
|[10]
|Grellmann, W., Reincke, K.: Quality improvement of elastomers. Use of instrumented notched tensile-impact testing for assessment of toughness. Materialprüfung 46 (2004) 168‒175; [https://doi.org/10.3139/120.100575 https://doi.org/10.3139/120.100575] 
|-valign="top"
|[11]
|Reincke, K., Grellmann, W., [https://de.wikipedia.org/wiki/Gert_Heinrich Heinrich, G.]: Investigation of mechanical and fracture mechanical properties of elastomers filled with precipitated silica and nanofillers based upon layered silicates. Rubber Chemistry and Technology 77 (2004) 662‒677 DOI: [https://doi.org/10.5254/1.3547843 https://doi.org/10.5254/1.3547843]
|-valign="top"
|[12]
|Reincke, K., Klüppel, M., Grellmann, W.: Investigation of fracture mechanical properties of filler-reinforced styrene-butadiene elastomers. Kautschuk Gummi Kunststoffe 62 (2009) 246‒251 [https://www.kgk-rubberpoint.de/wp-content/uploads/migrated/paid_content/artikel/858.pdf Download as pdf] 
|-valign="top"
|[13]
|Grellmann, W., Reincke, K.: Technical material diagnostics – Fracture mechanics of filled elastomer blends. In: Grellmann, W., Heinrich, G., Kaliske, M. Klüppel, M., Schneider, K., Vilgis, T. (Eds.): Fracture Mechanics and Statistical Mechanics of Reinforced Elastomeric Blends. Springer, Berlin (2013) 227‒268 
|}

[[Category:Fracture Mechanics]]
[[Category:Elastomers]]
[[Category:Film Testing]]
[[Category:Impact Tests]]