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" Enzyme-based Production of Nanocellulose from Soybean Hulls as a Green Filler for Rubber Compounding "
Bhadriraju, Vamsi
Ju, Lu-Kwang
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Latin Dissertation
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English
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| Record Number
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1058873
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TL57990
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| Main Entry
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Bhadriraju, Vamsi
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| Title & Author
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Enzyme-based Production of Nanocellulose from Soybean Hulls as a Green Filler for Rubber Compounding\ Bhadriraju, VamsiJu, Lu-Kwang
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| College
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The University of Akron
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| Date
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2020
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| Degree
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M.S.
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2020
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| Note
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99 p.
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| Abstract
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Nanocellulose has been investigated for use in food packaging, biomedical applications, and electronics. This work attempted to isolate and evaluate crystalline nanocellulose from soybean hulls in the form of cellulose nanofibrils (CNFs) as reinforcing fillers in natural rubber composites. CNFs and nanocrystalline cellulose (CNCs) have previously been derived from different types of lignocellulosic biomass. Previous work in this area used alkali pretreatments and acid hydrolysis to break down the complex network of cellulose, hemicellulose, and lignin present in plant cell walls. CNCs and CNFs have previously been isolated using high shear microfluidization, cryocrushing, freeze drying, and ultrafiltration. In this work, enzyme cocktails of carbohydrases produced from Aspergillus niger were used to hydrolyze the polysaccharides in soybean hull and soybean flour. Solids were separated from soluble sugars and other components after enzyme hydrolysis for 24 hours, and these washed solids were treated with sonication, blending, and homogenization to reduce the size of these solids. Particle size analysis showed that enzyme hydrolysis did indeed generate nanoparticles, the majority of which were between 150-200 nm. The quantity of these insoluble nanoparticles was found to be small, however, relative to that of solids and seed coat fragments approximately 100-200 µm in length. Further analysis with microscopy and SEM imaging revealed that the enzyme hydrolysis was able to cleave sclereid structures from the seed coat and breakdown soybean hull into fragments. Smaller particle size loading at the beginning of enzyme hydrolysis was found to release more sugar, so intermediate sizes were sieved in order to maximize solids recovery and minimize sugar release. These washed and mechanically treated solids were next mixed at alkaline pH (9.8–10) with natural rubber latex and oven dried overnight to create rubber composites. The resulting composites were masticated, vulcanized, and tensile tested in order to evaluate the efficacy of treated soybean hull solids as a reinforcing filler in natural rubber at 30 parts per hundred rubber (phr). Tensile testing results revealed that there was only an improvement of 3 MPa when compared to natural rubber, while rubber reinforced with carbon black improved tensile strength by a factor of 1.5. The results of this project showed that fillers derived through enzymatic hydrolysis and mechanical treatment of soybean hull marginally improve the tensile strength of natural rubber. It is suggested for future work that iterations of size reduction and filtration are performed to ensure that CNFs are the only solids in filler suspensions when compounded with natural rubber.
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Chemical engineering
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Ju, Lu-Kwang
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The University of Akron
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