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INVESTIGATOR: Pilla, S.

PERFORMING INSTITUTION:
CLEMSON UNIVERSITY
CLEMSON, SOUTH CAROLINA 29634

TRANSFORMING NANOCELLULOSE INTO AN ADVANCED BIORENEWABLE REINFORCEMENT WITH HYPERBRANCHED POLYMERS

NON-TECHNICAL SUMMARY: Forest restoration is key to healthy, sustainable forests that are resilient to major external factors (e.g., climate change). The Forest Service approach to accelerating forest restoration is based, in part, on creating high-value markets for low-value wood. One high-value material that has generated considerable recent interest and that can be extracted from wood removed during restoration is nanocellulose. Nanocellulose is widely available and has outstanding properties such as high stiffness and strength and low density, which makes it an excellent candidate as a bio-renewable reinforcement in the rapidly growing advanced polymer composites market. One logical market for nanocellulose penetration is automotive where the convergence of recent trends in lightweighting, nanotechnology, and the increasing use of natural fibers are favorable for nanocellulose adoption.In this project, we investigate innovative design architectures using nanocellulose and hyperbranched polymers, synthetically derived tree-like macromolecules, which when impregnated in polymers will yield high strength nanocomposites. Additionally, we propose a unique supercritical fluid assisted injection-molding technology to enhance dispersion of nanocellulose within the polymeric matrix, a key factor for augmenting performance. Overall, the goal is to transform the most desirable yet undervalued natural nanomaterial 'nanocellulose' into a high value advanced biorenewable reinforcement which, if successful, will open up entirely new avenues for nanocellulose use within the automotive industry and beyond.

OBJECTIVES: The proposed project provides a two-fold understanding of the nanocellulosic material. First, it provides a fundamental understanding of the performance characteristics of nanocellulose through innovative design architectures and covalent conjugate chemistries. Second, it investigates the applicability of engineered nanocellulose based roding nanostructures in high- value and superior-performance engineering applications such as those found in the automotive sector via a unique ScF-assisted manufacturing technology. The overall goal of the project is to use hyperbranched polymers to transform nanocellulose into an advanced biorenewable reinforcement. In support of this goal, the following objectives have been identified:1) Use novel conjugate chemistries to synthetically derive innovative design architectures that covalently couple nanocellulose, hyperbranched polymers (HBP), and polymer matrices that are relevant to the automotive industry (i.e. PP and PHBV).2) Employ a unique supercritical fluid (ScF) assisted processing technology to fabricate the roding nanostructure based nanocomposites.

APPROACH: To accomplish the stated objectives, we will undertake the following tasks using the methods indicated:Task-1: Synthesize nanocellulose-based HINGE and SERIES roding nanostructures by proposed, novel chemistry.Task-2: Manufacture roding-based polymeric nanocomposites using ScF technologyTask-3: Characterize nanostructures/nanocomposites by: NMR, FTIR, XRD, Raman, TEM, SEM, GPC, TGA, DMA, DSC, rheology and tensile tests.Task-4: Manufacture prototype automotive component using developed knowledge/techniques and based on automotive performance targets.

PROGRESS: 2019/03 TO 2020/03
Target Audience:?The results of this research were disseminated to: (1) the academic and scientific community through presentations and publications in technical conferences and scientific journals and; (2) the industrial community (through conferences). Additionally, the project and its results were introduced to CUICAR's students' working on its flagship vehicle prototyping program, DEEP ORANGE (DO). DO is a concept vehicle development program that immerses graduate automotive engineering students at CUICAR, PD Pilla's primary department, into the world of a future OEM and/or supplier. Working collaboratively, students, multi-disciplinary faculty, and participating industry partners focus on producing a new vehicle prototype each year. In this budget year, the project facilitated such dissemination methods and delivered projects' results to wide variety of audience including high school intern, graduate students, postdocs, etc. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project, in the fourth budget period itself, provided significant opportunities for training and personal development at multiple levels. Mainly, the mechanisms and science developed as part of the project's third year goals, were seamlessly integrated into the curriculum developed by the PD which expanded the training opportunity for the entire class that he taught, i.e. Advanced Composites Manufacturing Processes. It also provided advanced training for a postdoctoral fellow in terms of devising new chemistries for designing the proposed "roding" architectures. In summary, the project provided different levels of training and professional development ranging from an entire class of graduate students (through the curriculum developed by the PI), and a postdoctoral fellow (1). How have the results been disseminated to communities of interest?The results have been disseminated via peer-reviewed technical journals and presentations in scientific conferences. Journal publications: Zheng, Ting, Craig Clemons, and Srikanth Pilla. "A comparative study of direct compounding, coupling agent-aided and initiator-aided reactive extrusion to prepare cellulose nanocrystal/PHBV (CNC/PHBV) nanocomposite."ACS Sustainable Chemistry & Engineering(2020), 8(2). 814-822 Zheng, Ting and Srikanth Pilla. "Melt Processing of Cellulose Nanocrystal Filled Composites: Towards Reinforcement and Foam Nucleation" ACS Industrial & Chemistry Engineering, (in R2 revision) Zheng, Ting, Craig Clemons, and Srikanth Pilla. "Surface engineering of cellulose nanocrystals via bioinspired catechol chemistry and effect of graft length on reinforcement" (ready to submit) Conference presentations: Pilla S., "Engineering of Cellulose Nanocrystals via Bioinspired Catechol Chemistry and Effect of Graft Length on Reinforcement" at the 4th International Symposium on Materials from Renewables (ISMR) on October 9-10, 2019, University of Georgia, Athena, March 12, 2020 What do you plan to do during the next reporting period to accomplish the goals? To decorate HBP nanospheres of different diameters onto the end of PEG graft to engineer the "roding" architecture of variable dimensions of "space arm" and "spring". To advance the study of "roding" structure construction by using organic solvent-free and environmentally friendly methodology. To conduct microstructure analysis tests for synthesized "Roding" architectures. Disseminate the test results at international conferences and via publication medium. Optimize aforementioned integrated, laboratory approach for PP-CNC preparation and scale-up to pilot-scale using commercially-relevant processes.

IMPACT: 2019/03 TO 2020/03
What was accomplished under these goals? Major goals of this project The proposed project provides a two-fold understanding of the nanocellulosic material. First, it provides a fundamental understanding of the performance characteristics of nanocellulose through innovative design architectures and covalent conjugate chemistries. Second, it investigates the applicability of engineered nanocellulose based roding nanostructures in high-value and superior-performance engineering applications such as those found in the automotive sector via a unique ScF-assisted manufacturing technology. The overall goal of the project is to use hyperbranched polymers to transform nanocellulose into an advanced biorenewable reinforcement. In support of this goal, the following objectives have been identified: Use novel conjugate chemistries to synthetically derive innovative design architectures that covalently couple nanocellulose, hyperbranched polymers (HBP), and polymer matrices that are relevant to the automotive industry (i.e. PP and PHBV). Employ a unique supercritical fluid (ScF) assisted processing technology to fabricate the roding nanostructure-based nanocomposites. What was accomplished under these goals? Summary of deliverables for budget period 4: Developed a bio-inspired catechol chemistry to graft PEG on the CNC surface at aqueous solution. Grafted the CNC surface with PEG of different length and correlated the PEG length to the properties of the final composites. Investigated work lead to three journal articles and one conference presentation.

PUBLICATIONS (not previously reported): 2019/03 TO 2020/03
1. Type: Journal Articles Status: Published Year Published: 2020 Citation: Zheng, Ting, Craig Clemons, and Srikanth Pilla. "A comparative study of direct compounding, coupling agent-aided and initiator-aided reactive extrusion to prepare cellulose nanocrystal/PHBV (CNC/PHBV) nanocomposite." ACS Sustainable Chemistry & Engineering (2020), 8(2). 814-822
2. Type: Journal Articles Status: Under Review Year Published: 2020 Citation: Zheng, Ting and Srikanth Pilla. âMelt Processing of Cellulose Nanocrystal Filled Composites: Towards Reinforcement and Foam Nucleationâ ACS Industrial & Chemistry Engineering, (in R2 revision)
3. Type: Journal Articles Status: Other Year Published: 2020 Citation: Zheng, Ting, Craig Clemons, and Srikanth Pilla. "Surface engineering of cellulose nanocrystals via bioinspired catechol chemistry and effect of graft length on reinforcementâ
4. Type: Conference Papers and Presentations Status: Published Year Published: 2019 Citation: Pilla S., âEngineering of Cellulose Nanocrystals via Bioinspired Catechol Chemistry and Effect of Graft Length on Reinforcementâ at the 4th International Symposium on Materials from Renewables (ISMR) on October 9-10, 2019, University of Georgia, Athena, March 12, 2020

PROGRESS: 2017/03/15 TO 2018/03/14
Target Audience:The results of this research are targeted to be disseminated to: (1) the academic and scientific community through presentations and publications in technical conferences and scientific journals and; (2) the industrial community, by leveraging the partnership that Clemson University International Center for Automotive Research (CUICAR) has with over 100+ industries which includes OEMs, and tiered suppliers. Additionally, the project is anticipated to enable its results into CUICAR's vehicle prototyping program, DEEP ORANGE (DO). DO is a concept vehicle development program (http://goo.gl/6VYlfz) that immerses graduate automotive engineering students at CUICAR, PD Pilla's primary department, into the world of a future OEM and/or supplier. Working collaboratively, students, multi-disciplinary faculty, and participating industry partners focus on producing a new vehicle prototype each year. In the first budget year, the project facilitated such dissemination methods and delivered projects' results to wide variety of audience including high school intern, graduate students, postdocs, etc. Changes/Problems:The work is being carried out as planned. Changes if any may be reviewed during budget period 3 owing to the extensive chemistry involved in the synthesis of 'roding' nanostructure. At this point, no changes are proposed. What opportunities for training and professional development has the project provided?Similar to first budget period, the project provided significant opportunities for training and personal development at multiple levels. Mainly, it provided opportunity for a graduate studentto conduct research as part of hisgraduate studies. In addition, the mechanisms and science developed as part of the project's secondyear goals, were seamlessly integrated into the curriculum developed by the PD which expanded the training opportunity for the entire class that he taught, i.e. Advanced Composites Manufacturing Processes. It also provided advanced training for a postdoctoral fellow in terms of devising new melt processing method, compatibilization techniques, chemistries for designing the proposed "roding" architectures. The versatility of the project also allowed the involvement of twovisiting scholars, who got trained on the reinforcement capabilities of renewable, bio-based fillers. In summary, the project provided different levels of training and professional development ranging from twovisiting scholars (2), an entire class of graduate students (through the curriculum developed by the PI), graduate student(1), and a postdoctoral fellow (1). How have the results been disseminated to communities of interest? The results have been disseminated through multiple pathways. The first pathway of result dissemination was through publication in a refereed journal: Joy, J., Jose, C., Yu, X., Mathew, L., Thomas, S., Pilla, S., "The Influence of Nanocellulosic Fiber, Extracted From Helicteres isora, on Thermal, Wetting And Viscoelastic Properties of Poly(Butylene Succinate) Composites," Cellulose, 24(10), 4313-4323 (2017) The research results were also disseminated through two conference presentations: Clemons, C., "Towards Commercial Preparation of Composites from Cellulose Nanocrystals and Polypropylene: Drying, Dispersion, and Thermal Stability" at the 2017 Advancements in Fiber-Polymer Composites Conference on May 16-18, 2017 in Madison, WI Zheng, T., Pradeep, S.A., Clemons, C., Pilla, S., "Microcellular Foaming of Polypropylene- Cellulose Nanocrystal Composites," Fiber-reinforced Composites, International Symposium on Materials from Renewables, The Fiber Society's Fall 2017 Technical Meeting and Confer- ence, Athens, GA, USA (November 2017) The second pathway of result dissemination was conducted through the curriculum that the PI developed as part of his course, Advanced Composites Manufacturing Processes. The course curriculum was expanded by incorporating the novel mechanisms and science developed through the project and was disseminated to the class benefitting various graduate students. What do you plan to do during the next reporting period to accomplish the goals?Planned work for budget period 3: Optimize aforementioned integrated, laboratory approach for PP-CNC preparation and scale-up to pilot-scale using commercially-relevant processes. To advance, optimize and derive the effect of matrix and process on the filler/matrix interfacial interaction, and study its effect on the "Roding" filler with complex structure. To translate the developed compatibilizer/chain extender-facilitated study to polypropylene (PP) and conduct detailed study on its structure-property relationships including PP-CNC nanocomposites To advance the study of "Roding" structure construction by using organic solvent-free and environmental friendly methodology. To synthesize CNC-polymer hybrid with different arm lengths and construct HBP nanospheres To conduct microstructure analysis tests for synthesized "Roding" architectures. Disseminate the test results at international conferences and via publication medium

IMPACT: 2017/03/15 TO 2018/03/14
What was accomplished under these goals? Summary of deliverables for budget period 2: Developed an integrated, laboratory approach to treat and dewater cellulose nanocrystals and incorporate them into polypropylene with appropriate additives. The resulting compound can be used in conventional and microcellular injection molding.? Developed a methodology to prepare the PHBV/CNC by adding the compatibilizer. Developed a single-step melt processing method viain-situ grafting through the reactive extrusion. Investigated work lead to one journal paper andtwo conference presentations.

PUBLICATIONS: 2017/03/15 TO 2018/03/14
1. Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Zheng, T., Pradeep, S.A., Clemons, C., Pilla, S., ?Microcellular Foaming of Polypropylene- Cellulose Nanocrystal Composites,? Fiber-reinforced Composites, International Symposium on Materials from Renewables, The Fiber Society?s Fall 2017 Technical Meeting and Confer- ence, Athens, GA, USA (November 2017)
2. Type: Journal Articles Status: Published Year Published: 2017 Citation: Joy, J., Jose, C., Yu, X., Mathew, L., Thomas, S., Pilla, S., ?The Influence of Nanocellulosic Fiber, Extracted From Helicteres isora, on Thermal, Wetting And Viscoelastic Properties of Poly(Butylene Succinate) Composites,? Cellulose, 24(10), 4313-4323 (2017)
3. Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Clemons, C., ?Towards Commercial Preparation of Composites from Cellulose Nanocrystals and Polypropylene: Drying, Dispersion, and Thermal Stability? at the 2017 Advancements in Fiber-Polymer Composites Conference on May 16-18, 2017 in Madison, WI

PROGRESS: 2016/03/15 TO 2017/03/14
Target Audience:The results of this research are targeted to be disseminated to: (1) the academic and scientific community through presentations and publications in technical conferences and scientific journals and; (2) the industrial community, by leveraging the partnership that Clemson University International Center for Automotive Research (CUICAR) has with over 100+ industries which includes OEMs, and tiered suppliers. Additionally, the project is anticipated to enable its results into CUICAR's vehicle prototyping program, DEEP ORANGE (DO). DO is a concept vehicle development program (http://goo.gl/6VYlfz) that immerses graduate automotive engineering students at CUICAR, PD Pilla's primary department, into the world of a future OEM and/or supplier. Working collaboratively, students, multi-disciplinary faculty, and participating industry partners focus on producing a new vehicle prototype each year. In the first budget year, the project facilitated such dissemination methods and delivered projects' results to wide variety of audience including high school intern, graduate students, postdocs, etc. Changes/Problems:The work is being carried out as planned. No challenges have been found that could not be overcome and, therefore, no changes are planned. What opportunities for training and professional development has the project provided?The project, in the first budget period itself, provided significant opportunities for training and personal development at multiple levels. Mainly, it provided opportunity for three graduate students (PhDs) to conduct research as part of their graduate studies. In addition, the mechanisms and science developed as part of the project's first year goals, were seamlessly integrated into the curriculum developed by the PD which expanded the training opportunity for the entire class that he taught, i.e. Advanced Composites Manufacturing Processes. It also provided advanced training for a postdoctoral fellow in terms of devising new chemistries for designing the proposed "roding" architectures. The versatility of the project also allowed the involvement of a high school student and a visiting scholar, who got trained on the reinforcement capabilities of renewable, bio-based fillers. In summary, the project provided different levels of training and professional development ranging from a high school student (1), a visiting scholar (1), an entire class of graduate students (through the curriculum developed by the PI), PhD students (3), and a postdoctoral fellow (1). How have the results been disseminated to communities of interest?The results have been disseminated in multiple ways. The first pathway of result dissemination was through publication in refereed journals. The novel findings developed through the USDA funding in the first budget period lead to two articles (one published and one under review) in journals of large readership. 1) Joy, J., Jose, C., Varanasi, S. B., Mathew, L. P., Thomas, S., Pilla, S., "Preparation and Characterization of Poly (Butylene Succinate) Bionanocomposites Reinforced with Cellulose Nanofiber Extracted form Helicteres Isora Plant," Journal of Renewable Materials, 4(5), 351-364 (2016). 2) Joy, J., Jose, C., Yu, X., Mathew, L. P., Thomas, S., Pilla, S., "Thermal and Viscoelastic Behavior of Poly (butylene succinate)-Cellulose Nanofibril Biocomposites," Cellulose (Under Review) (2017). The second pathway of result dissemination was conducted through the curriculum that the PI developed as part of his course, Advanced Composites Manufacturing Processes. The course curriculum was expanded by incorporating the novel mechanisms and science developed through the project and was disseminated to the class benefitting various graduate students. The third pathway for result dissemination is through popular media. The Clemson University media group developed a video that manifested the proposed mechanism and how it influences the performance of the composites. The video is undergoing postproduction works. The video and article will be published soon, leading to further propagation of the project results and its benefits. What do you plan to do during the next reporting period to accomplish the goals?Planned work for budget period 2: To advance and optimize the functionalization and hydrophobization of CNC study To advance, optimize and derive the effect of GMA-grafting on thermophysical properties of PHBV and study its effect on chemical coupling with surface modified CNC To translate the developed PHBV surface-activation study to polypropylene (PP) and conduct detailed study on its structure-property relationships including PP-CNC nanocomposites To synthesize HBP- poly(ethylene glycol) hybrid with different arm lengths and construct HBP nanospheres To conduct molecular and microstructure analysis test results for synthesized HBP, modified CNC, and grafted polymers Initial structural and spectroscopic results of roding architectures Disseminate the test results at international conferences and via publication medium

IMPACT: 2016/03/15 TO 2017/03/14
What was accomplished under these goals? Summary of deliverables for budget period 1: Devised a methodology to functionalize and hydrophobize cellulose nanocrytsals (CNCs) Developed a process mechanism to activate poly(hydroxyl butyrate-co-valerate) (PHBV) using glycidyl methacrylate (GMA)-grafting via reactive extrusion Synthesized HBP-poly(ethylene glycol) hybrid-the first step in the development of our proposed HBP nanosphere (SPRING) structure Conducted studies on the feasibility of nanocellulose-based reinforcement agents Investigated work lead to two refereed journal articles (one published and one under review)

PUBLICATIONS: 2016/03/15 TO 2017/03/14
1. Type: Journal Articles Status: Published Year Published: 2016 Citation: Joy, J., Jose, C., Varanasi, S. B., Mathew, L. P., Thomas, S., Pilla, S., ?Preparation and Characterization of Poly (Butylene Succinate) Bionanocomposites Reinforced with Cellulose Nanofiber Extracted form Helicteres Isora Plant,? Journal of Renewable Materials, 4(5), 351-364 (2016).
2. Type: Journal Articles Status: Under Review Year Published: 2017 Citation: Joy, J., Jose, C., Yu, X., Mathew, L. P., Thomas, S., Pilla, S., ?Thermal and Viscoelastic Behavior of Poly (butylene succinate)-Cellulose Nanofibril Biocomposites,? Cellulose (Under Review) (2017).