11/09/2023
By Danielle Fretwell

The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a Doctoral Dissertation Defense by Shallal M. Alshammari on: Development of highly loaded polylactic acid/lignin biocomposites for material extrusion additive manufacturing.

Candidate Name: Shallal M. Alshammari
Degree: Doctoral
Defense Date: Nov. 22, 2023
Time: 11 a.m. -1 p.m.
Location: Ball Hall 323

Committee:
  • Advisor: Prof. Amir Ameli, Assistant Professor, Plastics Engineering, University of Massachusetts Lowell
  • Prof. Margaret J. Sobkowicz-Kline, Professor, Plastics Engineering, University of Massachusetts Lowell
  • Prof. Jay Hoon Park, Assistant Professor, Plastics Engineering, University of Massachusetts Lowell

Brief Abstract:
Polylactic acid (PLA)–lignin biocomposites are considered promising renewable green materials towards a sustainable future. One of their promising applications is additive manufacturing. However, the complex and heterogeneous structure of lignin, together with its poor rheological characteristics limit lignin incorporation at high contents (e.g., >20wt%). At such loadings, the melt processing is usually challenging, or the resultant composite exhibits high brittleness and low strength. Therefore, lignin is often chemically or physically modified to improve its dispersion in PLA, or a compatibilizer is added to increase the interfacial adhesion. Recently, a biopolymeric lignin, named Bioleum (BL) has been developed, which seems to offer better melt flowability and improved structural homogeneity, both of which are favored in manufacture of lignin based thermoplastic composites. Therefore, to develop high performance bioplastics with high lignin incorporation, this work has focused on a) the suitability of Bioleum for the preparation of PLA based composites at high lignin loadings, up to 40wt% using melt mixing strategies, b) compatibilization of PLA/BL biocomposites using polyethylene glycol (PEG) and triethyl citrate (TEC), c) glycidyl methacrylate (GMA) grafting of BL as a means to improve the mechanical properties of PLA/BL biocomposites, d) identifying the most promising material formulation and compounding strategy to scale the PLA/BL manufacturing process and fabricate filaments, and e) the performance assessment of PLA/BL as feedstock for 3D printing using material extrusion additive manufacturing.