Hu Zhou

In this work, various photocatalysts were synthesized with an impregnation-precipitation process to in situ decorate Ag-based nanoparticles (NPs, including Ag₃PO₄, AgCl, Ag₂O, and Ag₂CO₃) on the cellulosic paper. The structure and properties of the Ag-based composites were characterized by scanning electron microscopy, X-ray diffraction, transmitting electron microscopy, UV-vis diffuse reflectance spectra, and photocatalysis testing. The results showed that cellulosic paper is an efficient carrier which is feasible to grasp NPs due to the cellulosic nanofiber-network microstructure. Among the obtained samples, Ag₂CO₃ and AgCl NPs on cellulosic paper displayed high photocatalytic activity for the degradation of methyl orange under ultraviolet and visible light. However, photo lability of Ag₂CO₃ limits its recyclable. AgCl showed a better reutilization with the assistance of a surface plasmon resonance effect by Ag NPs that were grown in situ on the AgCl NPs, which formed Ag@AgCl nanocomposite structure. The photocatalytic activity of the AgCl/cellulosic paper decreased only slightly after three runs of photodegradation of methyl orange. The possible mechanism for photocatalysis was proposed. This work may provide a new method for the design of silver-based NPs/cellulosic paper nanocomposite photoreactors with favorable photocatalytic activities for industrial applications.

Purpose: This paper aims to provide a new drilling entry board for printed circuit board (PCB) process, superior in heat dissipation, lubrication, water solubility and hole location accuracy, achieving an excellent drilling process. Design/methodology/approach: Using a mixture of polyethylene glycol (PEG) and water-soluble adhesives as hydrosoluble, endothermic and lubricant resins and aluminum foils as baseplates, a series of coated and aluminous entry boards (CABs) for PCB drilling was successfully prepared. The surface appearance of the entry boards was observed clearly by scanning electron microscopy (SEM). The endothermic and lubricant effects of the resins applied on the CABs was characterized by differential scanning calorimetry (DSC) and their water solubility was tested in the normal-temperature water (25°C). Moreover, the CABs’ good drilling properties were tested when they were used for PCB drilling. Findings: The SEM analysis showed that the surfaces of the resin layers coated on the CABs whose coating thicknesses were less than 80 μm were smoother and flatter, which could improve hole location accuracy and reduce drill breakage ratio. By virtue of DSC, the endothermic and lubricant effects of the CABs were proven. The fusion of PEG in the resin layers could absorb the heat produced by drilling, restrain the temperature of the drill bit and hole rising and lubricate the drill bit efficiently when a hole was being drilled, which could achieve high-quality holes with good production efficiency. The water-soluble test showed that the prepared CABs had excellent water solubility at normal temperature, enabling the resin left on the hole walls and in the flute of the drill bit to be washed away easily and thereby improving the drilling efficiency and quality. The drilling tests showed that the increase in the thickness of the CABs’ coating could improve the hole location accuracy and alleviate the bit wear. In addition, the suitable coating thickness could ensure the firm adhering of the resin coating the aluminum foil, effectively avoid drill intertwist and prevent the resin debris from blocking the drilled holes on the surface of the entry board, which could hinder chip removal, resulting in poor hole wall quality and drill breakage. Originality/value: This paper has a remarkably high industrial practicality in the PCB manufacture process.

The polyurethane (PU) membranes with temperature and pH double sensitivities for water permeation were designed and prepared from a two‐step solution polymerization from the crystalline polycaprolactone diols (PCL), 4,4′‐diphenylmethane diisocyanate (MDI) and pH‐sensitive 2,2‐dimethylol propionic acid (DMPA), etc. The structure and properties of PU membranes were characterized by differential scanning calorimetry meter, contact angle tester, mechanical tester, porosity tests, water flux tests, water absorption tests, etc. Results showed that all PU membranes had a similar crystalline melting transition in their soft segments. With increasing DMPA content, or −COOH group content, the mechanical property of PU membranes was decreased, but the surface wettability and porosity of PU membranes were increased, which were expected to improve the water flux and water absorption of PU membranes. When the environment temperature was raised above the temperature of crystal‐melting transition (T_m) of the soft segments, the water fluxes across these PU membranes changed markedly, showing the temperature sensitivity. When pH varied around the dissociation constant (pKa) of DMPA contained in PU(2), PU(3) and PU(4) macromolecules, their water fluxes and water absorption were also obviously changed, showing the pH sensitivity. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.