Effect of laser processing parameters and carbon black on morphological and mechanical properties of welded polypropylene

AT McIlhagger, Foram Dave, Muhammad Ali, Mozaffar Mokhtari, Richard Sherlock, David Tormey

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4 Citations (Scopus)
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In the present work, laser process window and welding suitability of the neat isotactic polypropylene (iPP) and its carbon black (CB: 0–3 wt.%) composites was defined for laser transmission welding (LTW) with the help of thermal characterisation and thermal simulation. This novel approach of welding feasibility moves from trial and error to robust analytical methods. The non-contact spacer method is also a novel feature of this study, followed by X-ray diffraction of the laser-treated iPP composites. This study emphasises the importance of crystallinity in defining weld integrity and quality. The welding experiments were conducted with line energies of 0.06–0.12 J/ mm using the Response Surface Methodology approach by varying laser power and welding speed. The composites with 0.5 wt.% and 1.0 wt.% of CB were welded successfully with neat iPP, but composites with CB (>1 wt. %) were difficult to weld due to degradation. Weld lap shear strength and apparent weld width measured during mechanical testing showed better weld quality for 1 wt.%CB welded at line energy 0.12 J/m. Mathematical models have been developed based on the experimental results of central composite design after backward elimination. The present study demonstrates that an increase in CB to an optimised value fulfils the requirements of high welding speed with improved crystallinity and weld strength. This study is of keen interest to industrialists and researchers.
Original languageEnglish
Article number108216
Pages (from-to)1-13
Number of pages13
JournalOptics and Laser Technology
Early online date14 May 2022
Publication statusPublished (in print/issue) - 1 Sept 2022

Bibliographical note

Funding Information:
This research was funded by The North West Centre for Advanced Manufacturing (NWCAM) project is supported by the European Union’s INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB).

Publisher Copyright:
© 2022 The Author(s)


  • Laser transmission welding (LTW) Carbon black (CB) Thermal characterisation Polymer crystallinity Weld lap shear strength Optimisation in laser technology
  • Carbon black (CB)
  • Polymer crystallinity
  • Thermal characterisation
  • Laser transmission welding (LTW)
  • Optimisation in laser technology
  • Weld lap shear strength


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