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Displaying 1 - 25 of 96

Determination of the Complex Modulus of a Supported Ultra-Thin Polymer Film

October 12, 2021
Author(s)
Christopher C. White, Wen-Li Wu
A novel technique to quantitatively measure the complex modulus of ultra-thin polymer films (sub micron) is described. This technique employs a new mechanical impedance expression developed from a two-layer viscoelastic media model. This result is combined

EFFECTS OF PRE-STRAIN ON THE NON-LINEAR VISCOELASTIC PROPERTIES OF A MODEL SEALANT

November 18, 2020
Author(s)
Christopher C. White, Donald L. Hunston, Kar tean Tan
The non-linear viscoelastic properties of a model sealant were measured using stress relaxation tests conducted at different strain levels, x. Some specimens were measured with no previous strain history while others were given a preconditioning that

Bayesian Hierarchical Models for Service Life Prediction of Polymers

August 5, 2020
Author(s)
Adam L. Pintar, Christopher C. White, Li Piin Sung
Service life prediction for polymers remains an elusive goal. In this chapter, a general methodology first described in a previous study \cite{pintar2018predicting} is recapitulated and extended. A central component of the methodology is a Bayesian

Macroscopic degradation behaviors of polyethylene under the influence of UV radiation and temperature

February 17, 2020
Author(s)
Hsiang C. Hsueh, Jae H. Kim, Sara Orski, Andrew Fairbrother, Deborah Jacobs, Donald L. Hunston, Christopher C. White, Li Piin Sung, Lakesha Perry
Accelerated weathering tests were performed to investigate the effects of multiple ultraviolet (UV) light intensities and temperatures on the tensile behavior of high-density polyethylene (HDPE). In the macroscopic degradation behavior of HDPE, tensile

Validating Predictive Models with Outdoor Data

October 17, 2019
Author(s)
Christopher C. White, Donald L. Hunston, Li Piin Sung, Hsiang C. Hsueh, Adam L. Pintar, Deborah S. Jacobs
The NIST service life prediction program has demonstrated success in producing validated predictions for the property change resulting from outdoor exposure for a range of polymer systems including Epoxy, Polyethylene, Polyester, Polyethylene terephthalate

Degradation of sunglasses filters after long-term irradiation within solar simulator

September 18, 2019
Author(s)
Deborah Jacobs, Mauro Masili, Fernanda O. Duarte, Liliane Ventura, Christopher C. White
In our previous investigations on sunglasses standards, limits and requirements have been suggested for ocular safety. In this paper we evaluate the degradation of the lenses (category and ultraviolet protection) as sunglasses are exposed to solar

Temperature and light intensity effects on the photodegradation of high-density polyethylene

May 11, 2019
Author(s)
Andrew W. Fairbrother, Hsiang C. Hsueh, Jae Hyun Kim, Deborah S. Jacobs, Lakesha N. Perry, David G. Goodwin, Christopher C. White, Stephanie S. Watson, Li Piin Sung
The photodegradation of polymers poses a serious challenge to their outdoor application, and results in significant financial loss due to early or unexpected system failure. A better understanding of their degradation kinetics aids the improvement of

Exposure Study on the Aging of PTFE and Ceramic Diffusers

February 6, 2019
Author(s)
Benjamin K. Tsai, Catherine C. Cooksey, David W. Allen, Christopher C. White, Walter E. Byrd, Deborah S. Jacobs
This paper describes efforts to quantify the effects of aging in the ultraviolet (UV) on polytetrafluoroethylene (PTFE) and ceramic samples. Long term UV aging may significantly alter the reflectance factor and cause an error in the calibration of

Service Life Prediction Models to Predict Building Skin Failures

October 1, 2018
Author(s)
Christopher C. White, Donald L. Hunston, Adam L. Pintar
Determination of the in-service performance and failure of a building envelope material exposed to outdoor weathering has been a significant research goal for the last 100 years. Typically, estimations of the time to failure or durability of a material is

A Kinetics Based Models for Environmentally Induced Sealant Degradation

February 12, 2018
Author(s)
Donald L. Hunston, Christopher C. White
Caulks and sealants are a critical part of any structure that is exposed to the environment. Although they are good materials, they eventually fail, and the failure is often difficult to detect before extensive damage is generated by water ingress or loss

Accelerated Testing: Challenges and Opportunities.

December 19, 2017
Author(s)
Christopher C. White, Donald L. Hunston
Materials exposed to outdoor weathering will change properties. Currently there are no test methods that result in predictions for those materials. This lack of an ability to predict how the properties will change with weathering results in three problems

Service Life Prediction -Why is this so hard?

November 8, 2017
Author(s)
Christopher C. White, Kenneth M. White, James Pickett
Service life prediction in general and weathering lifetime in particular have been persistent problems despite nearly a century of work. Part of the problem has been a gap between the work of scientists studying material degradation and the practices

Measurements of the Photolytic Breakdown of Decabromodiphenyl Ether in Plastics

February 19, 2017
Author(s)
Marc R. Nyden, Rick D. Davis, Christopher C. White, H M. Stapleton, Nathan G. Dodder
In this talk, we report the product distributions and decomposition rates of DecaBDE when it is incapsulated in a common plastic, high impact polystyrene, and irradiated under controlled conditions using a calibrated source. The objective is to gain

ROLE OF SALT ON ADHESION OF AN EPOXY/ALUMINUM (OXIDE) INTERFACE IN AQUEOUS ENVIRONMENTS

November 5, 2015
Author(s)
Kar T. Tan, Christopher C. White, Donald L. Hunston, Justin M. Gorham, Michael Imburgia, Aaron M. Forster, Vogt D. Bryan
Engineering joints consisting of polymer/inorganic interfaces are commonly exposed to less than ideal conditions during normal service; these environmental conditions present a significant challenge for maintaining the structural integrity of the interface

Applied Strain on Sealant Samples Exposed to Outdoor Weather

October 19, 2015
Author(s)
Christopher C. White, Donald L. Hunston, Kar tean Tan
In outdoor exposures used to establish durability of sealant formulations, applied strain is typically absent. It is a critical aspect of the in-service environment. This research employs two recently available techniques to examine how the presence of

Aging of Polymeric Films used in Protective Glazing Systems

July 7, 2015
Author(s)
Christopher C. White, Donald L. Hunston, Kar T. Tan
The toughness of polymer and glass laminates or win-dow glazing, are used to protect buildings and occupants from shattered glass resulting from natural disasters (e.g., hurricanes, tornadoes, seismic events), and intentional events (e.g., robbery

ELEVATED TEMPERATURE ADHESION TESTING OF SPRAY-APPLIED FIRE-RESISTIVE MATERIALS

May 13, 2015
Author(s)
Christopher C. White, Kar T. Tan, Donald L. Hunston, Walter E. Byrd
Effective fire protection of steel can be fully realized when spray-applied fire resistive materials (SFRMs) are bonded sufficiently to structural steel during the event of fire. The adhesion mechanisms and characterization at elevated temperatures

MECHANISMS OF CRITICALITY IN ENVIRONMENTAL ADHESION LOSS

May 13, 2015
Author(s)
Christopher C. White, Kar T. Tan, Donald L. Hunston, Kristen L. Steffens, Deborah S. Jacobs, Bulent Akgun, Vogt D. Bryan
Moisture attack on adhesive joints is a long-standing scientific and engineering problem. A particularly interesting observation is that when the moisture level in certain systems exceeds a critical concentration, the bonded joint shows a dramatic loss of

Prediction of Sealant Modulus Change due to Outdoor Weathering

May 13, 2015
Author(s)
Christopher C. White, Kar T. Tan, Donald L. Hunston, Adam L. Pintar, James J. Filliben
An empirically-based model has been created to predict the change in modulus for a sealant exposed to outdoor weathering. The underlying high precision data supporting this model was obtained using the NIST SPHERE (Simulated Photo degradation by High

IMPACT OF ENVIRONMENTAL FACTORS ON POLYMERIC FILMS USED IN PROTECTIVE GLAZING SYSTEMS

March 11, 2015
Author(s)
Christopher C. White, Kar T. Tan, Donald L. Hunston, Aaron M. Forster, Deborah S. Jacobs
Accelerated and natural aging of safety films used in protective glazing systems was investigated by the use of Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy and tensile tests. Accelerated conditions involved simultaneous

Role of salt on adhesion of an epoxy/aluminium (oxide) interface in aqueous environments

February 16, 2014
Author(s)
Christopher C. White, Kar T. Tan, Donald L. Hunston, Justin M. Gorham, Aaron M. Forster, Vogt D. Bryan
The durability of adhesive joints in hostile environments is a major area of concern in structural adhesive bonding. Therefore, understanding the mechanics and mechanisms of degradation of adhesive joints is a key factor for more extensive use in future
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