Assessing the Elastic Moduli of Pavement Marking Tapes using the Tape Drape Test

Temporary pavement marking (TPM) tape adhesion with roadway surfaces is critical for tape performance. The two main TPM performance issues both stem from the adhesive strength. Weak adhesion results in premature detachment and excessive adhesion requires extensive removal processes that often leave ghost markings, both of which can cause dangerous confusion in road construction zones. Tape adhesion is directly related to the elastic modulus (E) role= presentation \u3e(E) of TPM tapes. Thus, accurate characterization of E role= presentation \u3eE before tape installation is essential to fully understand and predict the adhesion performance and ultimately the durability of TPMs. To determine the most appropriate E role= presentation \u3eE characterization technique for three different commercial TPM tape brands, two commonly used techniques—tensile and three-point bend testing—were compared with a less common technique, the Peirce cantilever testing or “Tape Drape Test” (ASTM D1388-18). The Tape Drape Test was the only method that accurately characterized E role= presentation \u3eE of tapes with raised surface features. Measured E role= presentation \u3eE values from tensile and three-point bend testing showed significant variation caused by the structural features of the tapes. The Tape Drape Test, which can be implemented quickly in the field before tape installation with little equipment, effectively characterized E role= presentation \u3eE for all the tapes to inform tape adhesion performances and installation procedures

Quality target negotiation in health care : evidence from the English NHS

We examine how public sector third-party purchasers and hospitals negotiate quality targets when a fixed proportion of hospital revenue is required to be linked to quality. We develop a bargaining model linking the number of quality targets to purchaser and hospital characteristics. Using data extracted from 153 contracts for acute hospital services in England in 2010/11, we find that the number of quality targets is associated with the purchaser’s population health and its budget, the hospital type, whether the purchaser delegated negotiation to an agency, and the quality targets imposed by the supervising regional health authority

Coupling Nanomechanical and Chemical Characterization for Evaluating Properties of Smallscale Molecular Crystals

Molecular crystals are used in a wide variety of applications, from pharmaceuticals and sweeteners to energetic materials. Understanding their chemical and mechanical properties provides insight into their performance and use. These properties are especially critical for energetic material systems, which may be sensitive to impact and require specific handling and storage practices. The mechanical properties of energetic molecular crystals are typically determined using nanoindentation by measuring elastic modulus, hardness, yield point, and fracture behavior. Reports of the properties and mechanical behavior of as-grown molecular crystals are limited due to the relative difficulty of performing good quality measurements. This work’s contributions include the first known measurements of elastic and plastic properties for crystals of DAAF, CL-20, NTO, ETN, and R-salt.When studying molecular crystalline systems, some important assumptions and behaviors typical to metallic and ionic systems begin to break down. The energetic material diaminoazoxyfurazan (DAAF) exhibits highly irregular mechanical behavior, which is likely explained by a complex combination of chemical and material attributes. This work investigates and compares the irregular mechanical response in DAAF—including high variance in mechanical properties, broad range of load-depth behavior, and non-conforming indentation impression geometries—to other energetic molecular crystals. The yield points (i.e., onset of plasticity) for several energetic materials, whose elastic modulus values range from 9.6 to 25.5 GPa, are also compared to identify the parameters that govern the onset of plasticity. This includes an investigation into yield point dependence on (or independence from) elastic modulus, hardness, near-neighbor spacing, and activation volume. When these materials reach the onset of plasticity, the maximum shear stress in each material ranges from 2-7% of their elastic modulus value. Analysis of the yield behavior in these materials suggests that there is not a strong correlation between yield stress and hardness, thus establishing that the mechanisms governing dislocation nucleation are not controlled by hardness, and vice-versa. By recognizing and accounting for the added complexities associated with inherently non-spherical molecules in a crystal lattice, this work advances the comprehension of mechanical response in molecular crystal systems

Mechanical Properties of Durable Pavement Marking Materials and Adhesion on Asphalt Surfaces

Mechanical properties of commercially available temporary pavement marking (TPM) tapes and thermoplastic materials used as permanent pavement markings (PPM) were investigated using the non-destructive Tape Drape Test and conventional mechanical testing. The impact of temperature and aging on the adhesion of TPM tapes and thermoplastic PPM applied to asphalt core surfaces with various surface roughness and treatments was determined using a modular peel fixture and shear adhesion tests. The adhesion of TPM tapes to model smooth surfaces decreased as surface temperature was increased from 0 to 40°C (32 to 104°F). For some tapes, reduced adhesion and brittle broken fracture were observed at the lowest investigated temperature of -20°C (-4°F). The adhesion of tapes applied to asphalt decreased significantly within 1 week of aging at -25°C (-13°F). Ghost markings were more likely at higher aging temperatures. For PPM thermoplastics, better adhesion to asphalt was observed for higher application temperatures and rougher surfaces. Asphalt emulsion treatments reduced the adhesion of thermoplastics and increased the likelihood of adhesive failure after 5 months of aging at -25°C (-13°F). More ductile PPM thermoplastic materials had better adhesion to both smooth and rough asphalt surfaces compared to thermoplastic materials with a more brittle mechanical response