Thesis (M.S.)--University of Wisconsin--Madison, 1946. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Columbia University. / Vita.

Hemp (Cannabis sativa L.) fibre is a natural renewable material which has been used in important areas closely related to people’s daily life. The increasing need of hemp fibre of high quality requires better fibre processing methods, more advanced facilities with higher machine performance and efficiency. Decortication is the key procedure to extract hemp fibre, and it significantly affects the output fibre quality and purity. The machine used for this process, known as a decorticator, needs to be well designed. The energy requirement is worth being evaluated for decorticators. This study consisted of two parts. In the first part, the specific energy of using a hammer mill for decorticating hemp was examined. The experimental data (three hammer mill screen scenarios and three feeding masses) were used to fit modified size-reduction theories (Kick’s, Rittinger’s and Bond’s laws). The experimental data were also used to develop a linear regression model to predict the specific energy from the ratio of initial and final fibre lengths. Results showed that all modified laws and the linear model performed equally well for specific energy prediction, and they had better prediction accuracy at a higher feed rate. In the second part of the study, integrated with virtual reality (VR) technology, TRIZ (“Theory of Inventive Problem Solving” in Russian) method was used for designing and evaluating a new hemp scutcher prototype in virtual environments. An evaluation system was developed for making comparison of the new design and the traditional scutchers. The new design is expected to have a better performance in terms of scale, product quality and energy efficiency. The TRIZ-VR integrated design has great potential to be a fast, reliable and low-cost design trend.

Separation of fibre from decorticated hemp mixture is important for fibre being use in diverse applications. The main goal of the study was to develop effective and efficient processes to obtain clean hemp fibre. Aerodynamic properties of hemp fibre and core were measured using aerodynamic method to separate fibre and core. Carding method was also used to obtain clean fibre under three different carding durations and five different feeding masses. The third method was the floatation method using water for separating fibre and core. For aerodynamic properties, fibre showed lower terminal velocity and higher drag coefficient than core. The differences in terminal velocity would allow fibres to be separated from core. Using the carding method, the fibre purity was increased from 55% up to 70%. Using the floatation method, the resultant fibre purity ranged from 85 to 90%. Present study discovers some promising methods for hemp fibre cleaning.

Hemp (Cannabis sativa L.) fibre is a natural renewable material which has been used in important areas closely related to people’s daily life. The increasing need of hemp fibre of high quality requires better fibre processing methods, more advanced facilities with higher machine performance and efficiency. Decortication is the key procedure to extract hemp fibre, and it significantly affects the output fibre quality and purity. The machine used for this process, known as a decorticator, needs to be well designed. The energy requirement is worth being evaluated for decorticators. This study consisted of two parts. In the first part, the specific energy of using a hammer mill for decorticating hemp was examined. The experimental data (three hammer mill screen scenarios and three feeding masses) were used to fit modified size-reduction theories (Kick’s, Rittinger’s and Bond’s laws). The experimental data were also used to develop a linear regression model to predict the specific energy from the ratio of initial and final fibre lengths. Results showed that all modified laws and the linear model performed equally well for specific energy prediction, and they had better prediction accuracy at a higher feed rate. In the second part of the study, integrated with virtual reality (VR) technology, TRIZ (“Theory of Inventive Problem Solving” in Russian) method was used for designing and evaluating a new hemp scutcher prototype in virtual environments. An evaluation system was developed for making comparison of the new design and the traditional scutchers. The new design is expected to have a better performance in terms of scale, product quality and energy efficiency. The TRIZ-VR integrated design has great potential to be a fast, reliable and low-cost design trend.

Separation of fibre from decorticated hemp mixture is important for fibre being use in diverse applications. The main goal of the study was to develop effective and efficient processes to obtain clean hemp fibre. Aerodynamic properties of hemp fibre and core were measured using aerodynamic method to separate fibre and core. Carding method was also used to obtain clean fibre under three different carding durations and five different feeding masses. The third method was the floatation method using water for separating fibre and core. For aerodynamic properties, fibre showed lower terminal velocity and higher drag coefficient than core. The differences in terminal velocity would allow fibres to be separated from core. Using the carding method, the fibre purity was increased from 55% up to 70%. Using the floatation method, the resultant fibre purity ranged from 85 to 90%. Present study discovers some promising methods for hemp fibre cleaning.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1943. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 68-71).

Thesis (M.E.)--University of Canterbury, 2006. / Typescript (photocopy). "September 2006." Includes bibliographical references (leaves 141-153). Also available via the World Wide Web.

Industrial hemp (Cannabis sativa) is an old crop being reintroduced into certain states; thus, very little information is known about growing the crop domestically. Two field experiments were established in Bowling Green, KY to evaluate various nitrogen fertilizer rates and timing applications to examine the effects on growth and yield of industrial hemp (Cannabis sativa). Each experiment was sprayed with 1.12 a.i. ha-1 pendimethalin on half of each plot as a pre – emergent herbicide. Hemp was planted at a rate of 43 kg/ ha into a conventionally tilled silt loam soil. Nitrogen rates studied were a control, 79, 157, and 236 kg N/ ha in the first experiment. In the second experiment, 157 kg N/ ha was applied at three timings along with a control. The three timings were: at establishment, side-dressed, and a split application of 78 kg at establishment and 78 kg side dressed. Plots were 6 m x 4.5 m and replicated 4 times for each experiment. Data collected included stand counts 34 days after planting (DAP), plant heights at 34 and 55 DAP, and stand counts, plant heights, fresh biomass, dried biomass, seed yield, and fiber yield at harvest (89 DAP) for both experiments. Increased fertilizer rates increased fresh and dried biomass which correlated with increased fiber yields. Different fertilizer timings had no effect on seed, biomass, or fiber yields. Herbicide had an early effect on stand counts and plant height in both experiments (

Increasing worldwide environmental awareness is encouraging scientific research into the development of cheaper, more environmentally friendly and more sustainable construction and packaging materials. Natural fibre reinforced thermoplastic composites are strong, stiff, lightweight and recyclable, and have the potential to meet this need. Industrial hemp fibre is amongst the strongest of the natural fibres available, and possesses a similar specific stiffness to E-glass, but with additional benefits such as low cost and low production energy requirements. The favourable mechanical properties of hemp, however, have yet to be transferred successfully to thermoplastic-matrix composite materials. The aim of this thesis was to achieve a greater understanding of the various parameters that contribute to composite strength and stiffness, and to manipulate these parameters in order to produce an improved hemp fibre reinforced polypropylene composite material. Hemp fibre was alkali treated at elevated temperatures in a small pressure vessel with either a solution of 10wt% NaOH or 5wt% NaOH / 2wt% Na2SO3. Single fibre tensile tests were performed on treated and untreated fibres, and it was found that the NaOH/Na2SO3 treatment produced the strongest and stiffest fibres with a good level of fibre separation. Lignin tests revealed that both alkali treatments were effective in the removal of lignin from hemp fibre, and XRD analysis showed that both alkali treatments resulted in increases in the hemp fibre crystallinity index. TGA and DTA analysis showed that the alkali fibre treatments improved the thermal stability of the treated hemp fibre when compared to the untreated fibre. Alkali treated hemp fibre, polypropylene and a maleic anhydride modified polypropylene (MAPP) coupling agent were compounded in a twin-screw extruder, and injection moulded into composite tensile test specimens. A range of composites with different fibre and MAPP contents were produced and tested. Tensile tests revealed that the optimum composite consisted of polypropylene with 40wt% NaOH/Na2SO3 treated hemp fibre and 4wt% MAPP, and had a tensile strength of 50.5 MPa and a Young's modulus of 5.31 GPa, respectively. The effect of MAPP on the fibre/matrix interface of NaOH/Na2SO3 treated hemp fibre/polypropylene composites was assessed by means of the single fibre fragmentation test. A composite consisting of NaOH/Na2SO3 treated fibres in a matrix of 4wt% MAPP and polypropylene was found to have a critical fibre length of 0.83mm and an interfacial shear strength of 16.1 MPa. The effects of MAPP on the composite fracture mechanisms were evaluated by means of SEM microscopy. TGA and DTA analysis showed that untreated hemp fibre composites and NaOH/Na2SO3 treated hemp fibre composites, each with a matrix of 4% MAPP and polypropylene, were less thermally stable than the polypropylene matrix alone. The Bowyer-Bader model was used to model the strength of an injection moulded composite with a normal fibre length distribution, consisting of 40wt% NaOH/Na2SO3 treated fibre, 4% MAPP and polypropylene. A theoretical composite tensile strength of 149 MPa was obtained from the model, based on the assumption that all the fibres were axially aligned in the composite. Composites with long, axially aligned fibres were produced using a novel solution mixing technique, where the polymer matrix and MAPP coupling agent were dissolved in a solvent and then precipitated inside an aligned fibre mat. Significant improvements in tensile strength and Young's modulus were achieved for solution mixed composites compared to composites produced by means of extrusion and injection moulding. The strongest solution mixed composite had a tensile strength of 84.7 MPa, and consisted of 56wt% NaOH/Na2SO3 treated fibre, 4% MAPP and polypropylene; and the stiffest injection moulded composite had a Young's modulus of 16.0 GPa, and consisted of 63wt% NaOH/Na2SO3 treated fibre, 4% MAPP and polypropylene.