Measuring Adhesive Cure By Dielectric Analysis

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Measuring Adhesive Cure By Dielectric Analysis

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Author : Robert Allen Rubitschun
language : en
Publisher:
Release Date : 1981

Measuring Adhesive Cure By Dielectric Analysis written by Robert Allen Rubitschun and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1981 with Adhesives categories.

Present methods of determining proper glueline cure are inadequate in either production or laboratory situations because they are time consuming and "after the fact". Monitoring the glueline while the wood composite is still in the press would provide many advantages over existing methods. Such a system would provide greater control over the degree of cure, helping eliminate variable quality in the glue bond. Dielectric spectroscopy has been proposed as a method capable of continuously monitoring adhesive cure and a specific machine, the Audrey II dielectrometer, has been advertised as being capable of detecting cure of resin systems common to the forest products industry. The objectives of this research were to determine if the Audrey II dielectrometer could measure cure of a highly caustic phenolic plywood adhesive and a resorcinol-formaldehyde laminating adhesive in Douglas-fir gluelines under conditions analogous to mill production. The dielectric spectrometer used in this study produced frequencies of 100-1000 Hz and measured voltage, capacitance, phase angle, and dissipation of the glued assembly placed between its electrodes. Capacitance was found to be the property that was most sensitive to changes in the wood-adhesive composite during the cure process. The dielectric spectrometer was able to accurately and consistently measure the capacitance of oven dried wood. Dielectric measurements were very sensitive to the presence of water, and the increase in capacitance with an increase in moisture content was reproducible. Problems were encountered when using the dielectric spectrometer to monitor cure of a resin in wood composites. The lack of repeatability in capacitance measurements led to the conclusion that the Audrey II dielectric spectrometer could not measure cure of a highly caustic phenolic adhesive or a resorcinolformaldehyde laminating adhesive in Douglas-fir gluelines. Components of a phenol-formaldehyde resin were examined to determine what caused the lack of reproducibility. The capacitance was reproducible with either water or aqueous caustic on the veneers. However, the presence of either phenol or formalin on the veneers resulted in a total lack of repeatability in capacitance. Both phenol and formalin are excellent swelling agents for wood and as wood swells, its microstructure is opened and plasticized. This would increase the capacitance. Other factors that would influence variation in swelling and capacitance would include depth of lathe checks, wood damage, porosity, density, and natural anatomical variation that influences the rate of penetration of chemicals into wood. Even considering the swelling effects and natural variation of wood, the variability in capacitance of the wood-adhesive composite is not readily understood.

Cure Monitoring For Composites And Adhesives

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Author : David Mulligan
language : en
Publisher: iSmithers Rapra Publishing
Release Date : 2003

Cure Monitoring For Composites And Adhesives written by David Mulligan and has been published by iSmithers Rapra Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Science categories.

This report focuses on in-line cure monitoring as a key way of optimising production. The bulk of this review is devoted to coverage of the range of techniques used for cure monitoring. Consideration is also given to other topics relevant to the implementation of cure monitoring processes. An additional indexed section containing several hundred abstracts from the Rapra Polymer Library database gives useful references for further reading.

Cure Analysis Of An Adhesive Primer

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Author :
language : en
Publisher:
Release Date : 1976

Cure Analysis Of An Adhesive Primer written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1976 with categories.

Selection of a cure cycle is generally based on the results of extensive physical properties tests. The advent of dielectric analysis provides the means of accurately predicting cure schedules without this extensive testing. Dielectric analysis is based on the reaction of the dipoles within a polymer to an alternating electric field. As the field alternates the dipoles attempt to swivel in step but are restricted because of their relatively fixed position within the polymeric structure. Capacitance is the measure of the dipole's ability to align and dissipation is the power lost in alignment. For a thermosetting polymer, dissipation versus time curves provide an insight into the curing mechanism and can be correlated to known physical and chemical changes. The dissipation versus temperature curves provide a fingerprint of the curing polymer and extent of cure. jg p8.

Temperature And Time Dependent Dielectric Measurements And Modelling On Curing Of Polymer Composites

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Author : Prastiyanto, Dhidik
language : en
Publisher: KIT Scientific Publishing
Release Date : 2016-03-15

Temperature And Time Dependent Dielectric Measurements And Modelling On Curing Of Polymer Composites written by Prastiyanto, Dhidik and has been published by KIT Scientific Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-03-15 with Dielectric measurements categories.

In this book a test set for dielectric measurements at 2.45 GHz during curing of polymer composites is developed. Fast reconstruction is solved using a neural network algorithm. Modeling of the curing process at 2.45 GHz using both dielectric constant and dielectric loss factor results in more accurate model compared to low frequency modelling that only uses the loss factor. Effect of various hardeners and different amount of filler is investigated.

Characterization And Cure Monitoring Of Structural Adhesives

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Author : Walter X. Zukas
language : en
Publisher:
Release Date : 1989

Characterization And Cure Monitoring Of Structural Adhesives written by Walter X. Zukas and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1989 with categories.

Two potential replacement adhesives for a discontinued commercial adhesive were investigated. The composition and curing behavior of the replacements were compared to the commercial system utilizing a number of analytical techniques. High performance liquid chromatography, size exclusion chromatography, and thermogravimetric analysis were applied to establish the lot-to-lot consistency of the adhesive component composition. The thermal, dynamic mechanical, rheological, and dielectric properties, as a function of cure, were monitored by differential scanning calorimetry, torsional braid analysis, parallel plate rheometry, and microdielectrometry, respectively. Correlations between the various techniques and the state of cure of the adhesive were made. The glass transition temperature of the adhesive was observed to be a very sensitive measure of the state of cure. Keywords: Adhesives, Characterization, Curing, Analytical techniques, Thermal analysis. (sdw).

Dielectric Cure Monitoring Of Composite Panels During Hot Pressing

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Author : Tyler G. Congleton
language : en
Publisher:
Release Date : 2001

Dielectric Cure Monitoring Of Composite Panels During Hot Pressing written by Tyler G. Congleton and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Adhesives, Hot melt categories.

Dielectric quantification of material properties is a technology well established in many industries. The application of this concept to the forest products industry to measure adhesive cure, however, has been belated in part due to a lack of proven technology directed at industrial processes and products. It is of great interest to manufacturers to minimize production costs and maximize output. This means being able to identify the minimum time required to cure composite panel products during hot pressing. In the hot-pressing process, material is currently pressed based on a conservative schedule that is actually longer than necessary. The schedule provides what temperatures and pressures are to be used throughout the press cycle to ensure resin cure (cross-linking). In the case of urea-formaldehyde, the resin is subject to strength loss if heat remains applied too long. The objective of the schedule is to cure the resin to an acceptable level and remove the product before degradation can occur. It is difficult to exactly predict the optimum point given all the variables to consider such as panel thickness; moisture and time; press pressure and temperature; and particle geometry, etc. This is where dielectric monitoring can help. Since the critical variable is degree of resin cure, it is logical to design a monitoring system that measures and utilizes it in a feedback control system. As the resin is curing, the molecules and ions become interlaced in a lattice structure during polymerization, reducing rotational and migrational mobility. Rotational and migrational mobility can be quantified dielectrically by applying an oscillating electric field to the material. Included in any monitored dielectric quantity is the effect due to moisture and wood. Studies were conducted to determine their contribution to the readings. Particleboard panels were manufactured in a laboratory environment and monitored with a dielectric system developed by the author. Three different adhesives were used urea - formaldehyde (U F), phenol formaldehyde (PF), and polymeric diphenolmethane diisocyanate (isocyanate, MDI). Dielectric response curves were obtained for each of the resins, and internal bond strength (IB) measurements were taken throughout the curing process of the boards. IB data were charted with dielectric data to show characteristics in the dielectric response curves that could be used to indicate cure status. The dielectric response curves show very encouraging peaks, valleys, and inflection points that seem to correspond to respective cure data. These characteristics could be incorporated into a full-scale system and used in an industrial setting to control and optimize press operations.

Cure Analysis Of An Adhesive Primer Br 125 A Modified Nitrile Epoxy

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Author :
language : en
Publisher:
Release Date : 1976

Cure Analysis Of An Adhesive Primer Br 125 A Modified Nitrile Epoxy written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1976 with categories.

Selection of a cure cycle is generally based on the results of extensive physical properties tests. The advent of dielectric analysis provides the means of accurately predicting cure schedules without this extensive testing. Dielectric analysis is based on the reaction of the dipoles within a polymer to an alternating electric field. As the field alternates the dipoles attempt to swivel in step but are restricted because of their relatively fixed position within the polymeric structure. Capacitance is the measure of the dipole's ability to align and dissipation is the power lost in alignment. For a thermosetting polymer, dissipation versus time curves provide an insight into the curing mechanism and can be correlated to known physical and chemical changes. The dissipation versus temperature curves provide a fingerprint of the curing polymer and extent of cure. The material evaluated in this study was BR-125 adhesive primer, a modified nitrile epoxy supplied by the Bloomingdale Division of American Cyanamid. Our application involved a special use of the primer as an adhesive which necessitated an alternative cure schedule. Typical curves of dissipation as a function of either time or temperature are shown. As a result of these curves, a minimum cure temperature was determined as well as an optimum cure cycle. T-Peel specimens were used to show that the alternate cure cycle suggested by the Audrey data was equivalent to the manufacturer's recommended cure and that the prediction of minimum cure temperature was also valid.

Handbook Of Thermoset Plastics

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Author : Hanna Dodiuk
language : en
Publisher: William Andrew
Release Date : 2021-10-25

Handbook Of Thermoset Plastics written by Hanna Dodiuk and has been published by William Andrew this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-10-25 with Technology & Engineering categories.

Handbook of Thermoset Plastics, Fourth Edition provides complete coverage of the chemical processes, manufacturing techniques and design properties of each polymer, along with its applications. This new edition has been expanded to include the latest developments in the field, with new chapters on radiation curing, biological adhesives, vitrimers, and 3D printing. This detailed handbook considers the practical implications of using thermoset plastics and the relationships between processing, properties and applications, as well as analyzing the strengths and weakness of different methods and applications. The aim of the book is to help the reader to make the right decision and take the correct action on the basis of informed analysis – avoiding the pitfalls the authors’ experience has uncovered. In industry, the book supports engineers, scientists, manufacturers and R&D professionals working with plastics. The information included will also be of interest to researchers and advanced students in plastics engineering, polymer chemistry, adhesives and coatings. Offers a systematic approach, guiding the reader through chemistry, processing methods, properties and applications of thermosetting polymers Includes thorough updates that discuss current practice and the new developments on biopolymers, nanotechnology, 3D printing, radiation curing and biological adhesives Uses case studies to demonstrate how particular properties make different polymers suitable for different applications Covers end-use and safety considerations

Encyclopedia Of Polymer Science And Technology Concise

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Author : Herman F. Mark
language : en
Publisher: John Wiley & Sons
Release Date : 2013-10-16

Encyclopedia Of Polymer Science And Technology Concise written by Herman F. Mark and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-10-16 with Science categories.

The compact, affordable reference, revised and updated The Encyclopedia of Polymer Science and Technology, Concise Third Edition provides the key information from the complete, twelve-volume Mark's Encyclopedia in an affordable, condensed format. Completely revised and updated, this user-friendly desk reference offers quick access to all areas of polymer science, including important advances in nanotechnology, imaging and analytical techniques, controlled polymer architecture, biomimetics, and more, all in one volume. Like the twelve-volume full edition, the Encyclopedia of Polymer Science and Technology, Concise Third Edition provides both SI and common units, carefully selected key references for each article, and hundreds of tables, charts, figures, and graphs.

Scientific And Technical Aerospace Reports

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Author :
language : en
Publisher:
Release Date : 1987

Scientific And Technical Aerospace Reports written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with Aeronautics categories.