World Nieh - Academia.edu (original) (raw)
Papers by World Nieh
Journal of Applied Polymer Science, 2003
Chemical Society reviews, Jan 23, 2018
A new family of materials comprised of cellulose, cellulose nanomaterials (CNMs), having properti... more A new family of materials comprised of cellulose, cellulose nanomaterials (CNMs), having properties and functionalities distinct from molecular cellulose and wood pulp, is being developed for applications that were once thought impossible for cellulosic materials. Commercialization, paralleled by research in this field, is fueled by the unique combination of characteristics, such as high on-axis stiffness, sustainability, scalability, and mechanical reinforcement of a wide variety of materials, leading to their utility across a broad spectrum of high-performance material applications. However, with this exponential growth in interest/activity, the development of measurement protocols necessary for consistent, reliable and accurate materials characterization has been outpaced. These protocols, developed in the broader research community, are critical for the advancement in understanding, process optimization, and utilization of CNMs in materials development. This review establishes d...
The effects of posttreatments of particle-board adhesive-type urea–formaldehyde resins were studi... more The effects of posttreatments of particle-board adhesive-type urea–formaldehyde resins were studied. The resins were synthesized with formaldehyde/first urea (F/U 1) mol ratios of 1.40, 1.60, 1.80, 2.10, and 2.40 and then the second urea was added to give a final formalde-hyde/urea ratio of 1.15 in alkaline pH. The resins were posttreated at 60°C for up to 13.5 h and the 2.5-h heat-treated resin samples were stored at room temperature for up to 27 days. Resins sampled during the posttreatments were examined by 13 C-NMR and evaluated by bonding particleboards. In the posttreatments, hydroxymethyl groups on the poly-meric resin components dissociated to formaldehyde and reacted with the second urea, and methylene and methyl-ene– ether groups were formed from reactions involving the second urea. Methylene– diurea and urea groups bonded to UF polymers were identified. As a result, the viscosity of the resins initially decreased but later increased along with the cloudiness of the resins. Bond-strength and formaldehyde-emission values of particleboard varied with posttreatment variables as well as with the F/U 1 mol ratios used in the resin syntheses. The results would be useful in optimizing resin synthesis and handling parameters. Various reaction mechanisms were considered.
Typical particleboard wood-adhesive urea–formaldehyde (UF) resins, synthesized with formaldehyde/... more Typical particleboard wood-adhesive urea–formaldehyde (UF) resins, synthesized with formaldehyde/first urea (F/U 1) mol ratios of 1.80, 2.10, and 2.40 and the second urea added to an overall F/U ratio of 1.15, in weak alkaline pH, were allowed to stand at room temperature over a period of 50 days. 13 C-NMR of time samples taken over the storage period showed gradual migration of hydroxymethyl groups from the polymeric first-urea components to the monomeric second-urea components and also an advancing degree of polymerization of resins by forming methylene and methylene ether groups involving the second urea. These phenomena that varied with the F/U 1 mol ratios used in the resin syntheses due to the varying polymer branching structures resulted in the first step of resin synthesis. Varying viscosity decreases and increases of the resins also occurred. Due to these chemical and physical changes, the particleboards that bonded with the sampled resins showed varying bond strength and formaldehyde-emission values, indicating process optimizations possible to improve bonding and formaldehyde-emission performances.
ACS Symposium Series, 1989
Industrial & Engineering Chemistry Research, 1991
... Mechanical Analysis Moon G. Kim* and World L.-S. Nieh Forest Products Laboratory, Mississippi... more ... Mechanical Analysis Moon G. Kim* and World L.-S. Nieh Forest Products Laboratory, Mississippi State University, Mississippi State, Mississippi 39762 ... The tan 6 curve maximum occurring during the rigidity increase was interpreted as the vitrification point of the resin. ...
Industrial & Engineering Chemistry Research, 1992
... Moon G. Kim,*it World L. Nieh,t Terry Sellers, Jr.,' and Wilbur W. Wilso... more ... Moon G. Kim,*it World L. Nieh,t Terry Sellers, Jr.,' and Wilbur W. Wilson* Forest Products Laboratory and Department of Chemistry, Mississippi ... calibration results based on the liiht scattering M, and intrinsic viscosity; [qITHF, intrinsic viscosity (mL/g) in THF; k', Huggins' constant in ...
Journal of Applied Polymer Science, 2003
Journal of Applied Polymer Science, 2003
Chemical Society reviews, Jan 23, 2018
A new family of materials comprised of cellulose, cellulose nanomaterials (CNMs), having properti... more A new family of materials comprised of cellulose, cellulose nanomaterials (CNMs), having properties and functionalities distinct from molecular cellulose and wood pulp, is being developed for applications that were once thought impossible for cellulosic materials. Commercialization, paralleled by research in this field, is fueled by the unique combination of characteristics, such as high on-axis stiffness, sustainability, scalability, and mechanical reinforcement of a wide variety of materials, leading to their utility across a broad spectrum of high-performance material applications. However, with this exponential growth in interest/activity, the development of measurement protocols necessary for consistent, reliable and accurate materials characterization has been outpaced. These protocols, developed in the broader research community, are critical for the advancement in understanding, process optimization, and utilization of CNMs in materials development. This review establishes d...
The effects of posttreatments of particle-board adhesive-type urea–formaldehyde resins were studi... more The effects of posttreatments of particle-board adhesive-type urea–formaldehyde resins were studied. The resins were synthesized with formaldehyde/first urea (F/U 1) mol ratios of 1.40, 1.60, 1.80, 2.10, and 2.40 and then the second urea was added to give a final formalde-hyde/urea ratio of 1.15 in alkaline pH. The resins were posttreated at 60°C for up to 13.5 h and the 2.5-h heat-treated resin samples were stored at room temperature for up to 27 days. Resins sampled during the posttreatments were examined by 13 C-NMR and evaluated by bonding particleboards. In the posttreatments, hydroxymethyl groups on the poly-meric resin components dissociated to formaldehyde and reacted with the second urea, and methylene and methyl-ene– ether groups were formed from reactions involving the second urea. Methylene– diurea and urea groups bonded to UF polymers were identified. As a result, the viscosity of the resins initially decreased but later increased along with the cloudiness of the resins. Bond-strength and formaldehyde-emission values of particleboard varied with posttreatment variables as well as with the F/U 1 mol ratios used in the resin syntheses. The results would be useful in optimizing resin synthesis and handling parameters. Various reaction mechanisms were considered.
Typical particleboard wood-adhesive urea–formaldehyde (UF) resins, synthesized with formaldehyde/... more Typical particleboard wood-adhesive urea–formaldehyde (UF) resins, synthesized with formaldehyde/first urea (F/U 1) mol ratios of 1.80, 2.10, and 2.40 and the second urea added to an overall F/U ratio of 1.15, in weak alkaline pH, were allowed to stand at room temperature over a period of 50 days. 13 C-NMR of time samples taken over the storage period showed gradual migration of hydroxymethyl groups from the polymeric first-urea components to the monomeric second-urea components and also an advancing degree of polymerization of resins by forming methylene and methylene ether groups involving the second urea. These phenomena that varied with the F/U 1 mol ratios used in the resin syntheses due to the varying polymer branching structures resulted in the first step of resin synthesis. Varying viscosity decreases and increases of the resins also occurred. Due to these chemical and physical changes, the particleboards that bonded with the sampled resins showed varying bond strength and formaldehyde-emission values, indicating process optimizations possible to improve bonding and formaldehyde-emission performances.
ACS Symposium Series, 1989
Industrial & Engineering Chemistry Research, 1991
... Mechanical Analysis Moon G. Kim* and World L.-S. Nieh Forest Products Laboratory, Mississippi... more ... Mechanical Analysis Moon G. Kim* and World L.-S. Nieh Forest Products Laboratory, Mississippi State University, Mississippi State, Mississippi 39762 ... The tan 6 curve maximum occurring during the rigidity increase was interpreted as the vitrification point of the resin. ...
Industrial & Engineering Chemistry Research, 1992
... Moon G. Kim,*it World L. Nieh,t Terry Sellers, Jr.,' and Wilbur W. Wilso... more ... Moon G. Kim,*it World L. Nieh,t Terry Sellers, Jr.,' and Wilbur W. Wilson* Forest Products Laboratory and Department of Chemistry, Mississippi ... calibration results based on the liiht scattering M, and intrinsic viscosity; [qITHF, intrinsic viscosity (mL/g) in THF; k', Huggins' constant in ...
Journal of Applied Polymer Science, 2003