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Dive into the research topics where John R. Collier is active.

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Featured researches published by John R. Collier.


Journal of The Textile Institute | 1991

Drape Prediction by Means of Finite-element Analysis

John R. Collier; Billie J. Collier; Gina O'Toole; S. M. Sargand

The draping behaviour of fabric treated as an orthotropic shell membrane is predicted by using a geometric non-linear finite-element method, and the results are compared with actual behaviour. A drape tester employing photovoltaic cells was designed and constructed to determine the drape coefficient of fabric specimens of 10-in. diameter. The warp- and weft-direction tensile moduli of these samples were determined by using a Kawahata Tensile and Shear Tester, and literature values of Poissons ratio were obtained. With this approach, excellent agreement between experimental and predicted drape coefficients resulted. For a 100% cotton plain-weave fabric, a drape coefficient of 68.4% was experimentally determined as compared with a predicted value of 71.0%.


Journal of Applied Polymer Science | 1998

Elongational rheology of polymer melts and solutions

John R. Collier; Ovidiu Romanoschi; Simioan Petrovan

Elongational rheological properties of polymer melts and solutions may be measured using nonlubricated flow characteristics through a semihyperbolic converging die. The effects of body forces related to developing orientation in the fluid during converging extensional flow are so strong that the shearing contribution become negligible in comparison, eliminating the need for lubrication to achieve an essentially pure elongational flow. The effective elongational viscosities of polypropylene melts and lyocell solutions correlated with shear-flow determinations were used to estimate the enthalpy and entropy changes as function of processing conditions. The flow of lyocell solutions through a converging die had, as a result, not only phase separation and cellulose crystallization, but also microfibers formation and high orientation.


Bioresource Technology | 2010

Enzymatic hydrolysis of cellulose dissolved in N-methyl morpholine oxide/water solutions.

Subramanian Ramakrishnan; John R. Collier; R. Oyetunji; B. Stutts; R. Burnett

In situ hydrolysis of cellulose (dissolving pulp) in N-methyl morpholine oxide (NMMO) solutions by commercially available Accellerase1000 is carried out. The yield of reducing sugars is followed as a function of time at three different temperatures and four different enzyme loadings to study the effect of system parameters on enzymatic hydrolysis. Initial results show that rates of hydrolysis of cellulose and yields of reducing sugars in the presence of NMMO-water is superior initially (ratio of initial reaction rates approximately 4) and comparable to that of regenerated cellulose (for times greater than 5h) when suspended in aqueous solutions. The usage of Accellerase1000 results predominantly in the formation of glucose with minimal amounts of cellobiose. This study proves the ability of cellulases to remain active in NMMO to carry out an in situ saccharification of cellulose thus eliminating the need to recover regenerated cellulose. Thus this work will form the basis for developing a continuous process for conversion of biomass to hydrogen, ethanol and other hydrocarbons.


Journal of Applied Polymer Science | 1996

Cellulosic reinforcement in reactive composite systems

John R. Collier; M. Lu; M. Fahrurrozi; Billie J. Collier

The two reactive systems using cellulosic fiber reinforcement emphasized in this article are twin screw extrusion maleation of polypropylene (PP) and structural reaction injection molding (SRIM). Both simultaneous and sequential compounding of sweet gum wood fiber (WF) with maleation were studied. Similar PP/WF mechanical properties are observed for simultaneous and sequential compounding. However, the melt viscosity of the simultaneous compounding and maleation deceases initially compared to neat polypropylene, whereas the sequential process does not have an initial decrease. After the initial response, the melt viscosity and shear thinning characteristics in both systems increase with WF content compared to their respective low WF behavior. The cellulosic reinforcement in the SRIM studies include: cheesecloth; and nonwoven mats formed separately from fiber bundles of sugar cane rind, kenaf, and sweet gum wood. In the SRIM system the modulus and tensile strength of the neat polyurea/urethane increases with cellulose content, independent of cellulosic source; the modulus doubles with only 4% cellulose, and the tensile strength doubles with only 7% cellulose. However, the elongation to break decreases from 300 to 30% with only 4% cellulose. Cellulose is as reactive with isocyanate in SRIM as are the commercial polyols.


Journal of Applied Polymer Science | 2001

Rheology of cellulosic N-methylmorpholine oxide monohydrate solutions of different degrees of polymerization

Simioan Petrovan; John R. Collier; Ioan I. Negulescu

Preparation and shear and elongational rheology of cellulose solutions of different degrees of polymerization (DP) in N-methylmorpholine oxide monohydrate (lyocell) were investigated. The dissolution process takes place in two stages, depending on the content of low and high DP fractions from the dissolving pulp blends. The influence of the DP of cellulosic chains on elongational and shear viscosity is greater at low deformation rates. Low DP solutions behave more like viscous fluids and the increase of the chain length brings about an increase of the elastic component. Orientation induced by the convergence flow is enhanced by the higher DP cellulosic chains.


Clothing and Textiles Research Journal | 1990

CAD/CAM in the Textile and Apparel Industry

Billie J. Collier; John R. Collier

CAD/CAM technology is becoming increasingly apparent in the textile and apparel industries in the U.S. These applications are reviewed, and integration of CAD/CAM technology throughout the production and marketing chain is emphasized and explored. Adoption of voluntary standards of electronic data usage is central to such integration. Training of students in textiles and clothing in the importance of electronic communication, as well as in the software and hardware involved, is an important task of textile and clothing educators. Additionally, the linkages between textile and apparel production and distribution should be emphasized, and the facilitation of these linkages is suggested as an important research focus.


Journal of Applied Polymer Science | 2000

Rheology of cellulosic N‐methylmorpholine oxide monohydrate solutions

Simioan Petrovan; John R. Collier; G. H. Morton

Shear dynamic and elongational rheology of concentrated solutions of cellulose in N-methylmorpholine oxide monohydrate (lyocell) were investigated at different temperatures and for two Hencky strains. Shear thinning and strain thinning behavior is characteristic for dynamic viscosity and effective elongational viscosity of lyocell solutions. Body forces, enthalpy, and entropy of orientation are high at low temperature and high deformation rates, showing a strong orientation effect.


Journal of Rheology | 1994

Polymer melt lubricated elongational flow

Hwan Chul Kim; Ajit Pendse; John R. Collier

Use of lubricated skin/core flow of a polymer melt and a hyperbolic shaped converging die are shown to result in essentially pure elongational flow at a constant elongational strain rate. This behavior is demonstrated first by modeling a series of skin/core layered flows: power‐law rectangular channel shearing flow; Newtonian fluid converging channel elongational flow; and power‐law fluid converging channel elongational flow. Experimental measurements using tracer particles and an image analysis system confirm the predicted behavior and demonstrate the ability to achieve a constant elongational strain rate in the core layer. The constant value is controlled by the volumetric flow rate and die geometry in this confined flow. The viscosity ratio of the core polymer must be at least 100 times that of the core and the converging flow channel must have a specific hyperbolic shape. A Dowex low‐density polyethylene skin and a Marlex polypropylene core were used for the experimental measurements and for the rheol...


Journal of Applied Polymer Science | 1996

Elongational viscosity of polymer melts: A lubricated skin-core flow approach

Ajit Pendse; John R. Collier

Previous work by this research group has shown that the use of a lubricated skin/core flow of polymer melts and a hyperbolic converging die results in an essentially pure elongational flow at a constant elongational strain rate in the core. The previous work was carried out on a laboratory-scale coextrusion system in a planar slit die; tracer particles and an image analysis system were used to confirm the predicted behavior. In this work, the technique was implemented first on the coextruder assembly, as a planar elongational rheometer, and then on a commercial capillary rheometer, as a uniaxial elongational rheometer for polymer melts. The later is achieved by replacing the standard capillary die with a hyperbolic axisymmetric die. A two-laycred billet is prepared for placement in the rheometer barrel by completely encapsulating the core polymer (the polymer to be analyzed) with a low-viscosity polyethylene skin. Commercial grades of polypropylenes, syndiotactic polystyrene, and nylon-66 were analyzed using this technique. Elongational viscosity at high extensional rates can be determined with this method; values in excess of 500 s−1 have already been achieved.


Proceedings of SPIE | 2015

ELI-Beamlines: development of next generation short-pulse laser systems

Bedrich Rus; P. Bakule; D. Kramer; J. Naylon; J. Thoma; J. T. Green; R. Antipenkov; M. Fibrich; J. Novák; F. Batysta; T. Mazanec; M. A. Drouin; K. Kasl; R. Baše; D. Peceli; L. Koubíková; P. Trojek; R. Boge; J. C. Lagron; Š. Vyhlídka; J. Weiss; J. Cupal; J. Hřebíček; P. Hříbek; M. Durák; J. Polan; M. Košelja; G. Korn; M. Horáček; J. Horáček

Overview of the laser systems being built for ELI-Beamlines is presented. The facility will make available high-brightness multi-TW ultrashort laser pulses at kHz repetition rate, PW 10 Hz repetition rate pulses, and kilojoule nanosecond pulses for generation of 10 PW peak power. The lasers will extensively employ the emerging technology of diode-pumped solid-state lasers (DPSSL) to pump OPCPA and Ti:sapphire broadband amplifiers. These systems will provide the user community with cutting-edge laser resources for programmatic research in generation and applications of high-intensity X-ray sources, in particle acceleration, and in dense-plasma and high-field physics.

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Billie J. Collier

Louisiana State University

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Xiaoling Wei

University of Tennessee

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Klaus Ertel

Rutherford Appleton Laboratory

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Y. W. Lo

Louisiana State University

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D. Neely

Rutherford Appleton Laboratory

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Paul D. Mason

Rutherford Appleton Laboratory

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S. Hawkes

Rutherford Appleton Laboratory

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Saumyabrata Banerjee

Rutherford Appleton Laboratory

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