Application of Unbleached and bleached modified low molecular weight kraft lignin as a biorenewable polymer for improving mechanical properties of 3D printing resin
Restricted (Penn State Only)
- Author:
- Rohi Gal, Mostafa
- Graduate Program:
- Agricultural and Biological Engineering (MS)
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- December 08, 2023
- Committee Members:
- Stephen C Chmely, Thesis Advisor/Co-Advisor
Amir Sheikhi, Committee Member
Suat Irmak, Program Head/Chair
Ali Demirci, Committee Member - Keywords:
- 3D printing
Mechanical strength
Kraft lignin
Chemical modification - Abstract:
- Uncovering an alternative to resins derived from fossil sources that possesses renewability, ecological sustainability, and economic feasibility is a pivotal advancement in advancing widespread industrial manufacturing using light digital processing printing technology. Lignin with distinguished properties including biorenewable, sustainable, and huge accessibility has exhibited potential in fulfilling these crucial requirements. Unfortunately, the technical Kraft lignin which produces in a huge amount about 70 million tons as a byproduct of pulp and paper industry around the world, only 1 to 2% of it is utilized to produce valuable products which is not significant than other types of lignin like Organosolv lignin. The objective of this study was to evaluate the effect of modified low molecular weight lignin with methacrylate anhydride before and after bleaching with hydrogen peroxide on mechanical properties of 3D printed object based commercial resin. In addition, extensive amount of work is required for optimization of bleaching reaction of hydrogen peroxide with modified lignin and evaluate the effect of different parameters of bleaching on the performance of bleached modified lignin in DLP printing technology. These findings serve as a crucial initial stride towards the development of 3D printable items incorporating technical lignin. In this study, the low molecular weight lignin was fractionated from the original technical Kraft lignin and acylation modification reaction with methacrylate anhydride was performed on it. In addition, the bleaching reaction with hydrogen peroxide is carried out in order to alleviate the light absorption ability of modified lignin. The obtained unbleached and bleached modified lignin in different concentration were blended with commercial resin to fabricate the 3D printed objects. Different chemical and mechanical characterizations were executed on obtained lignins, resins, and fabricated 3D printed objects respectively. Fractionation, modification, and bleaching reaction of low molecular weight Kraft lignin causes to apply high amounts of Kraft lignin in the formulation of resins more than 10% (w/w) which is 10 folds higher than the previous studies. The results demonstrated that the curing properties of formulated resin with unbleached modified lignin including penetration depth decreased remarkably about 70% from control sample without lignin to the resins containing 10 % lignin. Surprisingly, it is expected that experience increasing trend for the critical energy which is the minimum amount of energy to initiate the solidification of resin, but it was decreased with increasing the loading of lignin in the formulated resins than the control sample where the minimum amount of energy for initiating the polymerization reaction(Ec) was 662(2) and,0.763(1) mJ·cm-2 for the control sample and resins containing 10% (w/w) lignin) respectively. These properties were not measured for the formulated resin with bleached lignin and but it should be performed in the future work. Furthermore, the results for mechanical strengths showed that the tensile strength and strain at break of control sample (σ = 46.3(5) MPa, ε = 3.95(9) %) significantly decreased than for the resins formulated with 10% unbleached lignin (σ = 20(1) MPa) and increased brittleness (ε = 1.12(5) %). The values in the parenthesis show the last digit significant of standard error. The results of mechanical strength for blended resin with bleached modified lignin showed that with increasing the concentration of bleached lignin in the resin formulation at the same concentration than the unbleached one, the mechanical strength was decreased but it is indicated that the bleached lignin had less adverse effect on these properties which control and 10% bleached lignin had (σ = 46.3(5) MPa, ε = 3.95(9) %) and (σ = 35.2(1.7) MPa, ε = 2.7(2) %) respectively. These results showed that the fractionation of low molecular weight lignin from the original one is the crucial step to make possible the application of technical Kraft lignin in 3D printing area and consequently increases its valorization. It is also indicated that the acylation reaction of lignin is a necessary chemical modification to improve its miscibility in hydrophobic resin which can result in obtaining a homogenous resin. Uncovering an alternative to resins derived from fossil sources that possesses renewability, ecological sustainability, and economic feasibility is a pivotal advancement in advancing widespread industrial manufacturing using light digital processing printing technology. Lignin with distinguished properties including biorenewable, sustainable, and huge accessibility has exhibited potential in fulfilling these crucial requirements. Unfortunately, the technical Kraft lignin which produces in a huge amount about 70 million tons as a byproduct of pulp and paper industry around the world, only 1 to 2% of it is utilized to produce valuable products which is not significant than other types of lignin like Organosolv lignin. The objective of this study was to evaluate the effect of modified low molecular weight lignin with methacrylate anhydride before and after bleaching with hydrogen peroxide on mechanical properties of 3D printed object based commercial resin. In addition, extensive amount of work is required for optimization of bleaching reaction of hydrogen peroxide with modified lignin and evaluate the effect of different parameters of bleaching on the performance of bleached modified lignin in DLP printing technology. These findings serve as a crucial initial stride towards the development of 3D printable items incorporating technical lignin. In this study, the low molecular weight lignin was fractionated from the original technical Kraft lignin and acylation modification reaction with methacrylate anhydride was performed on it. In addition, the bleaching reaction with hydrogen peroxide is carried out in order to alleviate the light absorption ability of modified lignin. The obtained unbleached and bleached modified lignin in different concentration were blended with commercial resin to fabricate the 3D printed objects. Different chemical and mechanical characterizations were executed on obtained lignins, resins, and fabricated 3D printed objects respectively. Fractionation, modification, and bleaching reaction of low molecular weight Kraft lignin causes to apply high amounts of Kraft lignin in the formulation of resins more than 10% (w/w) which is 10 folds higher than the previous studies. The results demonstrated that the curing properties of formulated resin with unbleached modified lignin including penetration depth decreased remarkably about 70% from control sample without lignin to the resins containing 10 % lignin. Surprisingly, it is expected that experience increasing trend for the critical energy which is the minimum amount of energy to initiate the solidification of resin, but it was decreased with increasing the loading of lignin in the formulated resins than the control sample where the minimum amount of energy for initiating the polymerization reaction(Ec) was 662(2) and,0.763(1) mJ·cm-2 for the control sample and resins containing 10% (w/w) lignin) respectively. These properties were not measured for the formulated resin with bleached lignin and but it should be performed in the future work. Furthermore, the results for mechanical strengths showed that the tensile strength and strain at break of control sample (σ = 46.3(5) MPa, ε = 3.95(9) %) significantly decreased than for the resins formulated with 10% unbleached lignin (σ = 20(1) MPa) and increased brittleness (ε = 1.12(5) %). The values in the parenthesis show the last digit significant of standard error. The results of mechanical strength for blended resin with bleached modified lignin showed that with increasing the concentration of bleached lignin in the resin formulation at the same concentration than the unbleached one, the mechanical strength was decreased but it is indicated that the bleached lignin had less adverse effect on these properties which control and 10% bleached lignin had (σ = 46.3(5) MPa, ε = 3.95(9) %) and (σ = 35.2(1.7) MPa, ε = 2.7(2) %) respectively. These results showed that the fractionation of low molecular weight lignin from the original one is the crucial step to make possible the application of technical Kraft lignin in 3D printing area and consequently increases its valorization. It is also indicated that the acylation reaction of lignin is a necessary chemical modification to improve its miscibility in hydrophobic resin which can result in obtaining a homogenous resin.