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Licensed Unlicensed Requires Authentication Published by De Gruyter March 3, 2022

Influences on the mechanical properties of SRCs in a combined compacting and back injecting process

Fabian Jakob, Joshua Pollmeier and Hans-Peter Heim

Abstract

In this research paper, the effects of the combined compacting and back-injection process to produce back-injected self-reinforced composites on the mechanical properties of the self-reinforced composites (SRCs) are investigated. For this purpose, the parameters barrel temperature, time of injection and holding pressure were varied for the back injection. Tensile and bending tests were carried out on the SRCs. The results show that the mechanical properties depend to a large extent on the process parameters. The measured tensile strength varies between approx. 186 and 86 MPa, the stiffness between approx. 3500 and 2000 MPa. The flexural strength is measured between approx. 75 and 5 MPa, the flexural modulus between approx. 5480 and 650 MPa. Flexural tests are more suitable for evaluation of the consolidation, as tensile tests cannot evaluate the adhesion of the fabric layers to each other in the SRCs. Microscopic examinations show that consolidation by the back-injected melt can lead to smaller cross-sections in the SRCs compared to an area that was not back-injected. At high barrel temperatures, melting of individual fabric layers can occur, which explains, among other things, the drop in the mechanical properties of the SRCs.


Corresponding author: Fabian Jakob, IfW Plastics Technology, University of Kassel, Mönchebergstrasse 3, 34125 Kassel, Germany, E-mail:

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: None declared.

  3. Conflict of interest statement: The authors declare no conflicts of interest regarding this article.

References

Alcock, B. (2004). Single polymer composites based on polypropylene: processing and properties, Doctoral dissertation. Queen Mary University of London, London.Search in Google Scholar

Andrzejewski, J., Przyszczypkowski, P., and Szostak, M. (2018). Development and characterization of poly(ethylene terephthalate) based injection molded self-reinforced composites. Direct reinforcement by overmolding the composite inserts. Mater. Des. 153: 273–286, https://doi.org/10.1016/j.matdes.2018.04.084.Search in Google Scholar

Aurrekoetxea, J., Castillo, G., Cortes, F., Sarrionandia, M.A., and Urrutibeascoa, I. (2006). Failure of multimaterial fusion bonding interface generated during over-injection molding/thermoforming hybrid process. J. Appl. Polym. Sci. 102: 261–265, https://doi.org/10.1002/app.23696.Search in Google Scholar

Biermann, D., Gausemeier, J., Heim, H.-P., Hess, S., Peters, G., Ries, A., and Wagner, T. (2015). Planning and optimisation of manufacturing process chains for functionally graded components—part 2: case study on self-reinforced thermoplastic composites. Prod. Eng. Res. Devel. 9: 405–416, https://doi.org/10.1007/s11740-015-0610-2.Search in Google Scholar

Le Bozec, Y., Kaang, S., Hine, P., and Ward, I. (2000). The thermal-expansion behaviour of hot-compacted polypropylene and polyethylene composites. Compos. Sci. Technol. 60: 333–344, https://doi.org/10.1016/S0266-3538(99)00129-3.Search in Google Scholar

Cabrera, N., Alcock, B., Loos, J., and Peijs, T. (2004). Processing of all-polypropylene composites for ultimate recyclability. P I MECH ENG L-J MAT 218: 145–155, https://doi.org/10.1177/146442070421800208.Search in Google Scholar

Cherif, C. (2011). Textile Werkstoffe für den Leichtbau. Springer, Berlin Heidelberg.10.1007/978-3-642-17992-1Search in Google Scholar

Heim, H.-P., Biermann, D., and Maier, H. (Eds.). (2012). 1st International conference on thermo-mechanically graded materials. Verlag Wissenschaftliche Scripten, Auerbach.Search in Google Scholar

Heim, H.-P., Biermann, D., and Homberg, W. (Eds.). (2013). Functionally graded materials in industrial mass production, Vol. 2. Verlag Wissenschaftliche Scripten, Auerbach.Search in Google Scholar

Hine, P., Ward, I., Olley, R., and Bassett, D. (1993). The hot compaction of high modulus melt-spun polyethylene fibres. J. Mater. Sci. 28: 316–324, https://doi.org/10.1007/BF00357801.Search in Google Scholar

Hine, P., Ward, I., and Teckoe, J. (1998). The hot compaction of woven polypropylene tapes. J. Mater. Sci. 33: 2725–2733, https://doi.org/10.1023/A:1017540530295.10.1023/A:1017540530295Search in Google Scholar

Hine, P., Ward, I., Jordan, N., Olley, R., and Bassett, D. (2003). The hot compaction behaviour of woven oriented polypropylene fibres and tapes. I. Mechanical properties. Polymer 44: 1117–1131, https://doi.org/10.1016/S0032-3861(02)00809-1.Search in Google Scholar

Jakob, F., Pollmeier, J., and Heim, H.-P. (2021). Process influences in the combined compacting and back-injection process to produce back-injected self-reinforced composites (SRCs) – analysis via multiple regression modelling. Int. Polym. Proc. 36: 608–619.10.1515/ipp-2020-4105Search in Google Scholar

Jerpdal, L., Schuette, P., Ståhlberg, D., and Åkermo, M. (2020). Influence of temperature during overmolding on the tensile modulus of self‐reinforced poly(ethylene terephthalate) insert. J. Appl. Polym. Sci. 137: 48334, https://doi.org/10.1002/app.48334.Search in Google Scholar

Jordan, N., Bassett, D., Olley, R., Hine, P., and Ward, I. (2003). The hot compaction behaviour of woven oriented polypropylene fibres and tapes. II. Morphology of cloths before and after compaction. Polymer 44: 1133–1143.10.1016/S0032-3861(02)00810-8Search in Google Scholar

Menges, G., Haberstroh, E., Michaeli, W., and Schmachtenberg, E. (2011). Menges Werkstoffkunde Kunststoffe, 6th ed. Carl Hanser Verlag, Munich.10.3139/9783446443532Search in Google Scholar

Olley, R., Bassett, D., Hine, P., and Ward, I. (1993). Morphology of compacted polyethylene fibres. J. Mater. Sci. 28: 1107–1112, https://doi.org/10.1007/BF00400899.Search in Google Scholar

Paßmann, D. (2009). Prozessinduzierte Gradierung eigenverstärkter Polypropylen-Faserverbunde beim Heißkompaktieren und Umformen, PPH ZAPOL Dmochowski. Sobczyk Spółka Jawna, Szczecin.Search in Google Scholar

Rasburn, J., Hine, P., Ward, I., Olley, R., Bassett, D., and Kabeel, M. (1995). The hot compaction of polyethylene terephthalate. J. Mater. Sci. 30: 615–622, https://doi.org/10.1007/BF00356319.Search in Google Scholar

Ries, A. (2015). Thermo-mechanische Gradierung eigenverstärkter Polypropylen-Composite. Kassel University Press, Kassel.Search in Google Scholar

Ries, A. (2021). Structural description of self‐reinforced polypropylene composites. J. Appl. Polym. Sci. 138: e51215, https://doi.org/10.1002/app.51215.Search in Google Scholar

Ronniger, C.U. (2014). Taschenbuch der statistischen Qualitäts- und Zuverlässigkeitsmethoden. Die wichtigsten Methoden und Verfahren für die Praxis. CRGRAPH, Munich.Search in Google Scholar

Received: 2021-07-04
Accepted: 2021-11-24
Published Online: 2022-03-03
Published in Print: 2022-05-25

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