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Molecular Description of Heterophase Polymerization
Published in Hugo Hernandez, Klaus Tauer, Heterophase Polymerization, 2021
Quantification of homogeneity and heterogeneity is possible. Dispersity is a quantitative measure for heterogeneity that characterizes the degree of division of the heterophase system. It is defined as the reciprocal average characteristic length scale of the dispersed phase. A chemical system where all components are of similar size and perfectly miscible with each other appears homogeneous for any analytical technique at any moment of time that probes spatial dimensions, which are much larger than the molecular volume of the components (cf. Fig. 1.8A). If, however, reactants participate with molecular dimensions that differ by orders of magnitude like during polymerization, an apparently homogeneous system might appear heterogeneous (cf. Fig. 1.8C).
Product Engineering of Nanoscaled Materials
Published in Wolfgang Sigmund, Hassan El-Shall, Dinesh O. Shah, Brij M. Moudgil, Particulate Systems in Nano- and Biotechnologies, 2008
For particulate materials, the product properties depend on the chemical composition and on the dispersity of the material. The dispersity is characterized by the particle size distribution, the shape and morphology of particles and their interfacial properties. This relation was called by Rumpf [1] “property function,” and control of the property function is known as product engineering or product design.
Influence of PP-g-MA Compatibilization on the Mechanical and Wear Properties of Polypropylene/Thermoplastic Polyurethane Blends
Published in Tribology Transactions, 2018
Soner Savaş, Ayat Yaseen Al-Obaidi
The flexural stress–strain curves of PP, TPU, and PP/TPU blends with different PP-g-MA contents are shown in Fig. 5, and the relevant data are listed in Table 2. According to the Fig. 5, all samples reach a final stress-bearing capacity after a certain deformation and the stress continues to decrease after this level. The stress curves of the blends are intermediate between those of the pure PP and TPU. The effectiveness of PP/TPU weight ratios on the flexural strengths is the same as the results of tensile test. The blend morphology has an important influence on the reduction in properties. Blends with poor dispersity exhibit greater reduction in useful properties (Ajili, et al. (7)). In addition, the blend of the PP and TPU chains in a soft amorphous phase minimizes the mobility of the macromolecular polymer chains, which creates stiff PP/TPU blends when PP is the dominant phase (Jia, et al. (14)). Therefore, the PP75/TPU25 blends exhibit higher flexural properties (flexural strength and modulus) than PP25/TPU75 blends. In contrast to the tensile strengths, flexural strengths show different values at different PP-g-MA ratios. It is thought that the difference is related to the type of applied load in the test. In three-point bending, lower and upper surfaces of the samples are subjected to tension and compression, respectively (Savas, et al. (29)).
Enhancing the flowability of limestone water suspension for economical transportation by variation in particle size distribution
Published in Particulate Science and Technology, 2023
Asisha Ranjan Pradhan, Satish Kumar
Some researchers (Storms et al., 1990; Chang and Powell, 1994) looked at the numerous vital parameters influencing the flow behavior and foreseeing the viscosity of uni-modal and poly-dispersed spherical particle slurries. For slurries of polydispersed non-spherical particulates, the effects of form factor, density, and surface roughness on maximum volume fraction and particle contact under static and dynamic flow conditions must be studied (Metzner, 1985). Literature mentions little investigation of the rheological characteristics of limestone water suspension. A rheological investigation shows that it is feasible to pump a medium with nearly twice the solids content at a lower volumetric flow rate without significantly increasing the power consumption (Jaworska-Jóźwiak, 2021). It is well-known that as the solids loading in a particulate solution rises, so does its viscosity. Controlling the diameter ratio and composition of fine to coarse limestone particles might result in a significant reduction in viscosity and maximum solids concentration. This would be extremely advantageous for efficient and cost-effective pipeline transport of high-concentration limestone suspension by minimizing pumping costs and energy consumption (Senapati et al., 2019). The viscosity may be significantly reduced by altering the particle size distribution (PSD). PSD modification is a great strategy to get a high solid concentration while preserving a low viscosity (Vlasak and Chara, 2009; Singh et al., 2021; Kumar et al., 2008). Improving PSD is an excellent technique for high solids concentration while keeping the viscosity low. As a result, dispersity can reduce viscosity while maintaining equal solids content or permitting a more significant solid loading while maintaining the same viscosity.