On Developing a Hydrophobic Rubberized Cement Paste.

It is well known that most cement matrix materials are hydrophilic. For structural materials, hydrophilicity is harmful because the absorption of water will induce serious damage to these materials. In this study, crumb rubber was pretreated by partial oxidation and used as an additive to develop a hydrophobic rubberized cement paste. The pretreated crumb rubber was investigated using Fourier-transform infrared spectrometry (FT-IR) to understand the function groups on its surface. The pyrolysis oil adsorbed on the surface of the crumb rubber was observed by FT-IR and nuclear magnetic resonance (NMR) spectroscopy. A colloid probe with calcium silicate hydrate (C-S-H) at the apex was prepared to measure the intermolecular interaction forces between the crumb rubber and the C-S-H using an atomic force microscope (AFM). Pure cement paste, cement paste with the as-received crumb rubber, and cement paste with pretreated crumb rubber were prepared for comparison. FT-IR, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to understand the microstructure of the pastes. The static contact angle was used as the index of the hydrophobicity of the pastes. Experimental results showed that the hardened cement paste containing partially oxidized crumb rubber had excellent hydrophobic properties with an insignificant reduction in the compressive strength.

Recovery of cutting fluids and silicon carbide from slurry waste.

The wafer slicing process generates large amounts of slurry waste. The recovery of cutting oil and abrasives from slurry waste can reduce both the cost and environmental damage. A process combining magnetic precipitation and flocculation was developed for the recovery of cutting oil. A magnetic precipitation tank was employed for storage of the slurry and acceleration of the settlement of suspended particles. The larger particles further aggregate upon adding a non-aqueous flocculant comprising polyacrylamide (PAM) and ethylene glycol (EG). The recycled oil product is obtained by centrifugation and bag filtration. The physical properties and wafer dicing tests indicate that the recycled oil is qualified. Wafer manufacturers can thus reduce costs by using this process to produce recycled oil. A magnetic reactor with alkaline aqueous successfully recycled the SiC powder from the slurry waste by converting all the silicon species into sodium silica for further use. The results demonstrate that the magnetic reactor is able to remove most metal species and that the alkaline aqueous medium can recover all the Si substances in a sodium silicate solution, also called water glass.

On the Morphology of the SDS Film on the Surface of Borosilicate Glass.

Surfactant films on solid surfaces have attracted much attention because of their scientific interest and applications, such as surface treatment agent, or for micro- or nano-scale templates for microfluidic devices. In this study, anionic surfactant sodium dodecyl sulfate (SDS) solutions with various charged inorganic salts was spread on a glass substrate and dried to form an SDS thin film. Atomic force microscopy (AFM) was employed to observe the micro-structure of the SDS thin film. The effects of inorganic salts on the morphology of the SDS film were observed and discussed. The results of experiments demonstrated that pure SDS film formed patterns of long, parallel, highly-ordered stripes. The existence of the inorganic salt disturbed the structure of the SDS film due to the interaction between the cationic ion and the anionic head groups of SDS. The divalent ion has greater electrostatic interaction with anionic head groups than that of the monovalent ion, and causes a gross change in the morphology of the SDS film. The height of the SDS bilayer measured was consistent with the theoretical value, and the addition of the large-sized monovalent ion would lead to lowering the height of the adsorbed structures.