Thesis (M.P.H.)--University of Michigan, 1947.

Thesis (M.S.P.H.)--University of Michigan, 1939.

Thesis (M.S.P.H.)--University of Michigan, 1939.

Thesis (M.P.H.)--University of Michigan, 1947.

Natural fibers, such as hemp and flax, are emerging as cheaper reinforcing fibers for polymer composites. Renew-ability, comparable specific properties, and biodegradability make natural fibers more attractive than glass fibers. Vacuum Assisted Resin Transfer Molding (VARTM) is widely used to manufacture medium-to-large sized composites. The non-woven mats used in VARTM must meet manufacturing (permeability) and structural (volume fraction (Vf), thickness, fiber orientation, properties) requirements. Unlike glass mats, natural fiber mats are not available commercially. Design and development of natural fiber mats require knowledge on the relationship among manufacturing, structure and properties of these mats and their composites. Developing this knowledge is the objective of this thesis. Effect of needle punch density on hemp fiber mat structure (areal density, Vf, fiber orientation distribution (FOD), thickness, permeability) was systematically studied. The FOD was characterized non-destructively using X-ray tomography. The Effect of consolidation pressure during composite manufacturing on its structure (Vf, thickness, FOD) was studied. The modulus and strength of needle-punched hemp mat – thermoset polyester composites, manufactured using VARTM and compression molding, were measured. A predictive model for these properties and a modeling approach for the evolution of FOD and thickness during mat manufacturing were developed and validated. The results of these studies were used to understand the relationship. The modulus and the strength of the composites were significantly influenced by the Vf and the FOD, the evolution of which during composite manufacturing depended on the consolidation pressure and the mat structure. The latter depended on mat manufacturing parameters, namely the punch density used to bind the fibers together and the areal density of the web of fibers formed during air laying, and the FOD in the web. The permeability of the mat decreased with increasing the punch density and was found to be a function of both the Vf and the FOD. Despite this, the manufacturing of composite was not adversely affected, and the tensile modulus increased with punch density. The mat composite was modeled as an equivalent laminate, whose lay-up was determined using its FOD. The properties of equivalent laminate that was predicted using lamination theory compared well with the experimental results.

Natural fibers, such as hemp and flax, are emerging as cheaper reinforcing fibers for polymer composites. Renew-ability, comparable specific properties, and biodegradability make natural fibers more attractive than glass fibers. Vacuum Assisted Resin Transfer Molding (VARTM) is widely used to manufacture medium-to-large sized composites. The non-woven mats used in VARTM must meet manufacturing (permeability) and structural (volume fraction (Vf), thickness, fiber orientation, properties) requirements. Unlike glass mats, natural fiber mats are not available commercially. Design and development of natural fiber mats require knowledge on the relationship among manufacturing, structure and properties of these mats and their composites. Developing this knowledge is the objective of this thesis. Effect of needle punch density on hemp fiber mat structure (areal density, Vf, fiber orientation distribution (FOD), thickness, permeability) was systematically studied. The FOD was characterized non-destructively using X-ray tomography. The Effect of consolidation pressure during composite manufacturing on its structure (Vf, thickness, FOD) was studied. The modulus and strength of needle-punched hemp mat – thermoset polyester composites, manufactured using VARTM and compression molding, were measured. A predictive model for these properties and a modeling approach for the evolution of FOD and thickness during mat manufacturing were developed and validated. The results of these studies were used to understand the relationship. The modulus and the strength of the composites were significantly influenced by the Vf and the FOD, the evolution of which during composite manufacturing depended on the consolidation pressure and the mat structure. The latter depended on mat manufacturing parameters, namely the punch density used to bind the fibers together and the areal density of the web of fibers formed during air laying, and the FOD in the web. The permeability of the mat decreased with increasing the punch density and was found to be a function of both the Vf and the FOD. Despite this, the manufacturing of composite was not adversely affected, and the tensile modulus increased with punch density. The mat composite was modeled as an equivalent laminate, whose lay-up was determined using its FOD. The properties of equivalent laminate that was predicted using lamination theory compared well with the experimental results.

Thesis (Ed.D.)--Teachers College, Columbia University. / Typescript. Sponsor: Karl W. Bigelow. Dissertation Committee: Ethel M. Feagley, Maurice F. Tauber. Type C project. Includes bibliographical references (leaves 231-237).

Thesis (M.A.)--University of Wisconsin--Madison, 1966. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

"The purpose of this study is to survey the need for key punch operators in state government agencies and the adequacy of facilities in the Tallahassee, Florida area for training potential employees in this field. This study has attempted to determine the responsibility which business educators in the Tallahassee area have in providing trained personnel for automatic data-processing departments in state agencies. An effort was made to determine whether key-punch training and training for operators of other data-processing machines can best be given in business departments of schools in the Tallahassee area, in on-the-job training programs within the various state agencies, in offices of manufacturers of automatic data-processing equipment, or in cooperative programs"--Introduction. / Typescript. / "January, 1969." / "Submitted to the Graduate Council of Florida State University in partial fulfillment of the requirements for the degree of Master of Arts." / Advisor: Frank Dame, Professor Directing Study. / Includes bibliographical references (leaves 85-89).

No description available.