Fiber-yielding plants is an area of increased interest due to the potential use in a variety of green-based materials. These biocomposites can be incorporated into multiple uses; for example, to replace building materials and interior vehicular paneling. The research here aims to focus in on the crop Hibiscus cannabinus for utilization into these functions. H. cannabinus is economically attractive due to the entire process being able to be accomplished here in the United States. The plant can be grown in a relatively short growth period (120-180 days), and then processed and incorporated in a biocomposite. The plant fiber must first be broken down into a useable medium. This is accomplished by the retting process, which occurs when microbial constituents breakdown the heteropolysaccharides releasing the fiber. The research aims to bridge the gap between the primitive process of retting and current techniques in molecular and microbiology. Utilizing a classical microbiological approach, which entailed enrichment and isolation of pectinase-producing bacteria for downstream use in augmented microbial retting experiments. The tracking of the bacteria was accomplished by using the 16S rRNA which acts as “barcodes” for bacteria. Next-generation sequencing can then provide data from each environment telling the composition and microbial diversity of each tested variable. The main environments tested are: a natural environment, organisms contributed by the plant material solely, and an augmented version in which pectinase-producing bacteria are added. In addition, a time-course experiment was performed on the augmented environment providing data of the shift to an anaerobic environment. Lastly, a drop-in set was performed using each isolate separately to determine which contributes to the shift in microbial organization. This research provided a much needed modernization of the retting technique. Previous studies have been subject to simple clone libraries and growth plate assays and next-generation sequencing will bring the understanding of microbial retting into the 21st century.

The potential for Hibiscus cannabinus L. (kenaf) improvement via genome editing using the CRISPR/Cas9 system to generate gene knock-outs was explored. Studies included target gene identification, target guide RNA (gRNA) selection, plant tissue (explant) choice and media composition for plant regeneration. A putative kenaf phytoene desaturase gene (pds, GEED01047592.1) was identified in the kenaf transcriptome, and molecularly confirmed. Kenaf seedling tissues were transformed via Agrobacterium tumefaciens containing the cas9 gene (endonuclease required for gene knock-out) and each gRNA separately; putative transgenic calli and adventitious shoots arose on a medium containing 1-naphthaleneacetic acid, thidiazuron and silver nitrate. Tissues appeared chlorotic/albino and shoots remained diminutive/dwarf-like. These unique morphologies had also been noted by researchers who successfully knocked out the pds gene in other plant species. Cas9 DNA was detected in these putative transgenic kenaf tissues, but initial DNA sequencing analysis did not confirm knock-out/mutations in targeted areas of the pds gene.

Great interest has been generated in the use of natural fibres as environmentally friendly reinforcing materials in polymeric composites, which do not require high load bearing capabilities. kenaf fibres extracted from kenaf plants (hibiscus cannabinus) have been identified as an attractive option due to its production cost and the ability of the kenaf plants to grow in a variety of climatic conditions. Polypropylene (PP) has a relatively low production cost, excellent corrosion resistance, good retention of mechanical properties and less recycling challenges in comparison to other matrix systems such as thermosets. Given the individual advantages of kenaf fibre and polypropylene, kenaf reinforced polypropylene composites (kenaf/PP composites) have considerable commercial interest in the composite industry. However, limitations arise with respect to the mechanical performance and to the resistance to moisture absorption when natural fibres are used. This study focuses on the improvement of the mechanical properties (e.g. tensile, flexural, fatigue and impact properties) and the resistance to moisture absorption of kenaf reinforced polypropylene composites by means of fibre treatments (e.g. alkali and alkali-silane treatments) and the use of filler materials (e.g. functionalized multi-wall carbon nanotubes). Kenaf reinforced polypropylene composites are manufactured by a modified compression moulding using the film–stacking technique. The crux of this technique is that kenaf mats are impregnated with polypropylene powder in order achieve a uniform material distribution and to lower the manufacturing temperature, thereby preventing the thermal alteration of the composite constituents (e.g. kenaf fibres) and silano functional groups attached to the multi-wall carbon nanotubes. Fibre treatments including alkali treatments and alkali followed by silane treatments (alkali-silane) are considered in order to improve the fibre-matrix interfacial adhesion. The concentrations of the alkali solutions range from 1% to 8% in intervals of 1% by mass. Fibre contents ranging from 20% to 35% in interval of 5% by mass are considered for both kenaf and glass fibre reinforced plates. Functionalized multi-wall carbon nanotubes are used as filler material in order to improve the mechanical properties of the composite plates. The concentrations of the multiwall carbon nanotube (MWCNT) range from 0.1% to 1.25%. Mechanical test and microscopic examination results showed that alkali treatments improve the mechanical properties of kenaf/PP composites. However, the improvements due to alkali-silane treatments were found to be more significant because additional silane treatments substantially enhanced the fibrematrix interfacial adhesion. Material failures in untreated kenaf/PP composites and alkali treated kenaf/PP composites were mainly characterized by fibre pullouts, whereas in alkali-silane treated kenaf/PP composites they were characterised by fibre breakage. Alkali concentrations of 5% and 6% NaOH are found to the optimum concentrations for both alkali treatment and alkali-silane treatment. The use of functionalized MWCNTs as filler material improved furthermore the mechanical properties of kenaf/PP-MWCNT composites in comparison to those of kenaf/PP and glass/PP composites. The main contributing factors of the improvements were found to be the enhancement of the interfacial adhesion between the nanoparticles and the matrix, and also between the nanoparticles and kenaf fibres. Material failures in kenaf/PP-MWCNT composites were characterized by fibre breakage and matrix cracks. The optimum MWCNT concentrations were found to be 0.5% and 0.75%. 30% fibre contents was found to be the optimum fibre content for both kenaf/PP and kenaf/PP-MWCNT composites. Test results showed that the fibre treatments, especially alkali-silane treatment, improved the resistance to moisture absorption of the composites. Test results also showed that the manufacturing technique, which enables the manufacturing of composite plates with layers of different moisture diffusion resistances, has a significant influence on the resistance of kenaf/PP composites. The addition of multi-wall carbon nanotubes to the polypropylene matrix did not alter the moisture absorption resistance of kenaf/PP-MWCNT composites. The impregnation of kenaf and fibre glass mats with polypropylene powder significantly lowered the manufacturing temperature

No description available.

Limited information exists regarding the processing parameters and extent of reinforcing potential natural fibers have in polymer matrices. The five natural fiber mats studied were low shive flax, mid shive flax, high shive flax, hemp and kenaf. The parameters characterized were fiber size, wax content, surface contact angle, and shive content. The compressive force and unsaturated permeability was measured for each mat, and composites were constructed and tested using selected mats in a soy-based polyurethane (PU) matrix. All mats exhibited a viscoelastic behavior under compression, and an increase in shive content correlated with an increase in relaxation. The presence of shive and larger fiber size increased the permeability. Higher wax content and contact angle lowered the permeability. The mechanical properties for all composites performed better than the neat PU, showing there was matrix to fiber adhesion and load transfer. Hemp outperformed the other fibers studied in all mechanical tests.

In an effort to present more ‘green’ material for massive manufacturing that are both competitive in their properties and can be more environmental friendly, natural fibers are being considered for possible applications in the automotive industry. This paper shows an exploratory study of the effects of pressure and layup on a hybrid composite of randomly oriented woven kenaf fibers and fiberglass/polyester sheet molding compound (SMC). In addition to initial testing performed on their water absorption and other important properties, these hybrid composites were tested to determine the bending modulus of elasticity (MOE) and the bending modulus of rupture (MOR) as well as the tensile modulus of elasticity (MOE), ultimate tensile strength. Pictures are taken from a Spectral Electron Microscope to determine if the fiber mats were properly penetrated by the resin and if the structural integrity of the fibers was maintained during manufacture.

The evaluation of production alternatives in agriculture requires a close examination of their economic and environmental impacts. This study was conducted to identify the crops with the highest profit potential given terminal market prices over the last five years, evaluate the feasibility of adopting new crop alternatives, given historical price information and limited production resources, and determine the potential environmental impacts of adopting new cropping strategies in Accomack and Northampton Counties on the Eastern Shore of Virginia. A database of daily terminal price information was created to identify the market windows for specific commodities, their respective high, median and low prices, and their price variability over the last five years. A linear programming model was used to determine optimal farming operations for those farmers that grow only wheat and soybean versus farmers who are willing and able to include vegetables in their crop mix. PLANETOR, an environmental impact computer program, was used to estimate the potential soil erosion, pesticide leaching and runoff, nitrogen leaching, and phosphorous runoff for different scenarios. The model shows that some of the new vegetable commodities could substantially increase the net returns of the farming operations in question. Romaine and Boston Lettuce were consistently selected as the most profitable alternatives while the region's traditional crops offered little competition. Wheat and soybean production showed acceptable levels of soil erosion, as defined by the T-values for the region, and low potential for nitrogen leaching. They did, however, exhibit a higher potential for water contamination, through leaching, or runoff, of high toxicity chemicals. Although lettuce production had higher than recommended soil losses, a well-diversified crop mix offsets its negative impacts at the farm level. Lettuce also uses low toxicity chemicals, decreasing potential health hazard from their leaching or runoff. The introduction of the new vegetable commodities is recommended on the basis of the high profits that they offer, as well as the more positive pesticide leaching and runoff potential. Their final adoption, however, should take place only after establishing a well defined marketing strategy and resolving potential marketing problems. No crop exists that could offer both high profits and have no impact on the environment. Kenaf was thought to be one, but it was soon eliminated on both grounds. This study showed, however, that the new vegetable crops considered may offer better net returns, while they do not necessarily translate into environmental disasters. / Master of Science

Bio-composites are increasing in demand due to governmental incentives across the globe for both environmental and human health reasons. The ideal bio-composite is renewable, recyclable, available, and non-toxic. To properly engineer bio-composite products, the physical properties of the fiber as well as fiber/matrix interactions must be known. The problem lies in the fact that many suitable natural fibers are not currently available in a material form that may be easily worked with. This research investigates methods to process raw kenaf (hibiscus cannabinus) on a scale that allows researchers to make more consistent samples for testing. Though kenaf is highlighted, these processing methods may be applied to any natural fiber. The raw fibers are processed into kenaf chopped strand mats (KCSM) by adapting basic paper-making techniques. KCSM exhibit paper-like qualities and mechanical properties and provide a material of uniform thickness for use in composite parts. Also presented are a basic understanding of natural fiber constituents and effects of mechanical and co-mechanical treatments on those constituents. To test KCSM, samples are made for the ASTM D3039 tensile testing and for testing in a dynamic material analyzer (DMA). Both mechanically and chemo-mechanically processed samples are made for the purpose of comparison. Also, I-beam bridges are built with KCSM to demonstrate how KCSM may be used to create a structure. This is spurred on by the annual SAMPE bridge competition that includes special categories for natural fiber beams. The lay-up procedure is shown in detail to provide a framework that future competitors may use to build quality I-beams for this competition. The properties obtained by using the KCSM are competitive with other reported properties for kenaf-based composites. A kenaf I-beam demonstrates a strength-to-weight ratio that is 65% of a berglass I-beam built to the same dimensions. Trade-os of using KCSM are the random 2d-fiber orientation and brittle failure, which are not usually desirable in composite components. The chemically treated samples indicate a higher degree of crystallinity but demonstrate inferior mechanical properties when compared to the untreated samples.

No description available.

Natural fibers show potential to replace glass fibers in thermoset and thermoplastic composites. Kenaf is a bast-type fiber with high specific strength and great potential to compete with glass fibers. In this research kenaf/epoxy composites were analyzed using Dynamic Mechanical Analysis (DMA). A three-point bend apparatus was used in the DMA testing. The samples were tested at 1 hertz, at a displacement of 10 μm, and at room temperature. The fiber volume content of the kenaf was varied from 20%-40% in 5% increments. Ten samples of each fiber volume fraction were manufactured and tested. The flexural storage modulus, the flexural loss modulus, and the loss factor were reported. Generally as the fiber volume fraction of kenaf increased, the flexural storage and flexural loss modulus increased. The loss factor remained relatively constant with increasing fiber volume fraction. Woven and chopped fiberglass/epoxy composites were manufactured and tested to be compared with the kanaf/epoxy composites were manufactured and tested to be compared with the kenaf/epoxy composites. Both of the fiberglass/epoxy composites reported higher flexural storage and flexural loss modulus values. The kenaf/epoxy composites reported higher loss factor values. The specific flexural storage and specific flexural loss modulus were calculated for both the fiberglass and kenaf fiber composites. Even though the kenaf composites reported a lower density, the fiberglass composites reported higher specific mechanical properties.