scholarly journals Methodology for determining time-dependent mechanical properties of tuff subjected to near-field repository conditions

10.2172/59155 ◽  
1983 ◽  
Author(s):  
J.D. Blacic ◽  
R. Andersen
Keyword(s):  
Mechanical Properties ◽  
Near Field ◽  
Time Dependent

scholarly journals Oxazoline-based crosslinking reaction for coatings

2021 ◽  
Author(s):  
Philipp Knospe ◽  
Patrick Böhm ◽  
Jochen Gutmann ◽  
Michael Dornbusch
Keyword(s):  
Mechanical Properties ◽  
Loss Modulus ◽  
New Technology ◽  
Sol Gel ◽  
Polymer Network ◽  
Time Dependent ◽  
Crosslinking Reaction ◽  
Coating Materials ◽  
Rheological Measurements ◽  
Excellent Adhesion

AbstractNowadays, coating materials must meet high demands in terms of mechanical, chemical and optical properties in all areas of application. Amongst others, amines and isocyanates are used as crosslinking components for curing reactions, meeting the highly demanding properties of the coatings industry. In this work, a new crosslinking reaction for coatings based on oxazoline chemistry is investigated with the objective to overcome disadvantages of established systems and fulfill the need for sustainable coating compounds. The oxazoline-group containing resin, synthesized from commercially available substances, undergoes cationic self-crosslinking polymerization to build up a network based on urethane and amide moieties. NMR-, IR- and ES-mass spectroscopy are suitable techniques to characterize the synthesized oxazoline monomers, which are linked to polyisocyanates and polymerized afterwards via self-polymerization. The progress of crosslinking is followed by changes in IR spectra and by rheological measurements to calculate time dependent values for storage and loss modulus. The glass transition temperature of the resulting coating is determined, too. Furthermore, sol–gel-analysis is performed to determine the degree of crosslinking. After application on steel and aluminium panels, application tests are performed. In addition to excellent adhesion to the substrate, the polymer network shows promising mechanical properties and with that it could represent a new technology for the coatings industry.

scholarly journals Evolution of Network Structure and Mechanical Properties in Autonomous-Strengthening Dental Adhesive

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2076 ◽  
Author(s):  
Rizacan Sarikaya ◽  
Linyong Song ◽  
Qiang Ye ◽  
Anil Misra ◽  
Candan Tamerler ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Network Structure ◽  
Permanent Deformation ◽  
Hydrolytic Stability ◽  
Time Dependent ◽  
Rational Approach ◽  
Aqueous Environment ◽  
Experimental Sample ◽  
Dental Resins ◽  
By Products

The inherent degradation property of most dental resins in the mouth leads to the long-term release of degradation by-products at the adhesive/tooth interface. The by-products increase the virulence of cariogenic bacteria, provoking a degradative positive-feedback loop that leads to physicochemical and mechanical failure. Photoinduced free-radical polymerization and sol‒gel reactions have been coupled to produce a novel autonomous-strengthening adhesive with enhanced hydrolytic stability. This paper investigates the effect of network structure on time-dependent mechanical properties in adhesives with and without autonomous strengthening. Stress relaxation was conducted under 0.2% strain for 8 h followed by 40 h recovery in water. The stress‒time relationship is analyzed by nonlinear least-squares data-fitting. The fitted Prony series predicts the sample’s history under monotonic loading. Results showed that the control failed after the first loading‒unloading‒recovery cycle with permanent deformation. While for the experimental sample, the displacement was almost completely recovered and the Young’s modulus increased significantly after the first test cycle. The experimental polymer exhibited higher degree of conversion, lower leachate, and time-dependent stiffening characteristics. The autonomous-strengthening reaction persists in the aqueous environment leading to a network with enhanced resistance to deformation. The results illustrate a rational approach for tuning the viscoelasticity of durable dental adhesives.

Thermo-Mechanical Investigation of Free Volume Theory for Polyamie-6

2016 ◽  
Vol 819 ◽  
pp. 580-584
Author(s):  
Jamal Umer ◽  
Ivan Saprounov ◽  
Igor Emri ◽  
Barbara Zupančič ◽  
Muhammad Wakil Shahzad
Keyword(s):  
Mechanical Properties ◽  
Free Volume ◽  
Polyamide 6 ◽  
Time Dependent ◽  
Effect Of Temperature ◽  
Free Volume Theory ◽  
Wlf Equation ◽  
Mechanical Investigation ◽  
Temperature And Pressure

Polymers always show time-dependent mechanical properties. In order to use polymers in engineering applications, long-term mechanical propertes should be characterized. Free volume theroy is the mostly used theory to predict and model the mechanical properties of polymers. The effect of temperature is modelled thorugh William-Landel-Ferry (WLF) equation, whereas, the combined effect of temperature and pressure is modelled by Filler-Moonan-Tschoegl (FMT) equation. Both of the models are based on free volume theory. A set of expermentations were performed to investigate the validity of free volume concpet for one of the most important engineering polymer; i.e. Polyamide-6.

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