03/10/2023
By Danielle Fretwell

The Francis College of Engineering, Department of Plastics Engineering, invites you to attend a doctoral dissertation proposal defense by Shallal Alshammari on “Development of highly loaded polylactic acid/lignin biocomposites for material extrusion additive manufacturing.”

Candidate Name: Shallal Alshammari
Degree: Doctoral
Defense Date: Thursday, March 16, 2023
Time: 1 to 3 p.m. EDT
Location: Ball Hall 323. Those interested in attending should contact Shallal_alshammari@student.uml.edu and committee advisor, amir_ameli@uml.edu at least 24 hours prior to the defense to request access to the meeting.

Committee:

  • Advisor Amir Ameli, Assistant Professor, Plastics Engineering, University of Massachusetts Lowell
  • Margaret J. Sobkowicz-Kline, Professor, Plastics Engineering, University of Massachusetts Lowell
  • 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. However, the complex and heterogeneous structure of lignin, together with its poor flowability and 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. Over the past few decades, poly (lactic acid) has been incorporated with several types of lignin in various process, such as melt compounding and extrusion, to produce sustainable biocomposite materials for 3d printing filaments or other applications. However, the composites produced are usually exhibit poor lignin dispersion and weak interfacial adhesion between the blend components, resulting in reduced mechanical properties, such as tensile strength and elongation at break, as compared to neat PLA. Therefore, lignin is often chemically or physically modified to improve its dispersion in poly (lactic acid), or a compatibilizer is added to increase the interfacial adhesion.

Recently, a new melt-flowable biopolymeric lignin with improved structural homogeneity, named Bioleum (BL), has been developed. Due to its appealing thermo-mechanical characteristics, Bioleum may offer great promise toward manufacture of thermoplastic biocomposites.

In this context, the specific objectives of the proposed project are a) investigate the suitability of Bioleum for the preparation of PLA based composites at high lignin loadings, up to 40wt% using a small scale compounding process, b) assess the compatibility of PLA/BL biocomposites at the presence of polyethylene glycol (PEG) or triethyl citrate (TEC) as plasticizers, c) investigate the potential of GMA grafting as a means to improve the mechanical properties of the PLA/BL biocomposites, d) identify the most promising material formulation and compositing strategy and scale the compounding process using a pilot-scale extrusion system, and e) fabricate PLA/BL filaments and assess their performance for 3D printing using material extrusion additive manufacturing.

All interested students and faculty members are invited to attend the defense in person.