Static loading test methods to characterize the resistance against slow crack growth use surfactants to shorten testing times. In comparison, the cracked round bar test method uses cyclic loading but no accelerating media and/or temperatures. To allow for a comprehensive knowledge on the effect of media influence, this research investigates the effect of air as well as deionized water with and without surfactant on the crack growth performance of blow-molding polyethylene in cracked round bar experiments at various temperatures. As also seen in literature, first test results show a crack growth decelerating effect of surfactant in cyclic tests at an elevated temperature. Ongoing tests will show the temperature dependency of these effects.
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Keywords: Engineering polymers
REACTIVE TELECHELIC POLYETHERIMIDE TOUGHENED TETRAFUNCTIONAL EPOXY
Highly crosslinked multifunctional epoxy resins possess superior properties, like high Tg, modulus, chemical resistance, etc, yet they are brittle due to their high crosslink density. It is desired that toughness improvements should not compromise other properties, including mechanical, thermal properties, and processability. Here, reactive polyetherimide containing amine functional end groups with two different molecular weights and loading levels were incorporated in tetraglycidyl diamino diphenyl methane tetrafunctional epoxy resin to study their structure-property relationship.
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FRACTURE CHARACTERIZATION OF DUCTILE POLYMERS: RECENT APPLICATIONS OF THE LOAD SEPARATION CRITERION
For ductile polymers, the development of sound relationships between material structure and fracture response calls for the use of robust testing methodologies able to measure properties that describe the different processes occurring during fracture. The most common testing methods used with these materials appear inadequate, and there is a need to examine new approaches. This paper describes the most recent applications of the load separation criterion (LSC) in the fracture characterization of ductile polymers: the testing procedures are introduced and some representative results shown.
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RUPTURE OF HYDROGELS
Hydrogels are soft, highly deformable materials with applications ranging from soft actuators to natural and synthetic biomaterials. The rupture of hydrogels generally involves very large deformations that can be strongly coupled to the fluid flow. In this paper, a modified J-integral (J*) is used to calculate the critical energy release rate utilizing either a critical stretch criterion or the measured overall force-extension relation for a SENT specimen of a fibrin gel, which is the primary stress-carying component of blood clots.
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