Engineering Commons^™

Early-Age Strength And Failure Characteristics Of 3d Printable Polymer Concrete: Numerical Modelling And Experimental Testing, Mohammad Amin Dehghani Najvani

Civil Engineering ETDs

The time-dependent rheological and early-age strength parameters of Polymer concrete (PC) were investigated. PC flow decreased, and the static yield stress and thixotropy increased as the specimen aged, while the dynamic yield stress remained unchanged. The study found that the Herschel-Bulkley model can accurately describe the PC’s rheological behavior over time. The change in cohesion strength and internal friction angle over time was observed using uniaxial unconfined compression and direct shear tests of fresh PC. A time-dependent MohrCoulomb failure criterion was established. Temperature analysis was used to determine the gel time and explain the evolution of the time-dependent early-age strength …

Synthesis Of Glucomannan-Xylan Composite Biofilms: Characterization And Applications For Food Packaging, Kholoud Al-Ajlouni

Dissertations

Scientists are most concerned about the need for green alternatives for efficient food packaging polymers to replace petroleum-based packaging products. The waste of corn cobs and the roots of the konjac plant contain hemicellulose, xylan and glucomannan respectively, and can be used to produce biofilms for food packaging.

The aim of these studies is to formulate biofilms from glucomannan-xylan blends that compete with petroleum-based plastic wrap. The biofilms must be strong, smooth, transparent, have a water vapor barrier, have the required mechanical properties and be cheap. Biofilms from glucomannan were stiff, lacked mechanical properties, and absorbed moisture. Therefore, it reacts …

Investigating The Rheological Behavior Of A Simple Yield Stress Fluid Under Shear Flows, Francesco Accetta

Theses

Many soft materials display unique and complex rheological behavior characterized by a transition from a solid-like to a fluid-like state upon the application of a force that exceeds the threshold to flow, known as the yield stress. Yield stress fluids are found in a wide range of commonly encountered materials including microgels, emulsions, and foams, and have been widely studied by rheologists over the last several decades. Carbopol is a popular polymeric microgel system as it displays simple, non-thixotropic rheological behavior and is typically seen as an ideal yield stress fluid. Previous research has demonstrated the reproducible behavior of shear …