Low density polyethylene and linear low density polyethylene (LDPE/LLDPE (60wt.%/40wt.%))as basic materials, intumescent flame retardant ammonium polyphosphate (APP) was added into them to obtain fire retardant systems. The molding parameters, fire retardant properties, mechanical properties and processing properties of samples were examined. It was showed the rotational speed of main screw was 28-34rad/min. when samples were molded, cylinder temperature was 185-195°C, mold temperature was 85-115°C, preheating time was 5-10min and filling time was 8-21s. APP had good fire retardant and smoking suppression functions. Adding 30% (wt.%) APP can obtain grade of FV-0. With APP content increasing, the mechanical and processing properties of materials decreased.
In recent years, the machinability of magnesium alloy is concerned more and more by the public. In this paper, a study on the cutting properties of magnesium alloy AZ91D when dry turning with kentanium cutting tools is presented. It shows the cutting force measured by a data acquisition system which is made up of Kistler9257B piezoelectric crystal sensor dynamometer, Kistler5070A10100 charge amplifier and computer. The effect of cutting parameters on cutting force was studied, and the experimental formula was built. The tool wear and chip characteristics were observed with KYKY-EM3200 electron scanning microscope and EDAX PV9900 alpha ray spectrometer, while the surface roughness of the workpiece was measured with 2205 profilometer. Results showed that the cutting depth was the main influence factor on cutting force, followed by feed rate and cutting speed . The main form of tool wear showed to be diffusive wear and adhesive wear. The feed rate had the main influence on chip form and the workpiece surface roughness, cutting speed was less effective, the cutting depth was the least.
Nano-structured magnesium hydroxide (nano-MH) has been added into LDPE/LLDPE, the technological parameters, flame and mechanical properties, M.F.R. of LDPE/LLDPE/nano-MH samples have been examined. It is indicated two time extruder pelletization is a good technological route, which can make nano-MH disperse evenly in PE. The optimum rotational speed of screws changes from 37 to 42 rad/min, the die pressure changes from 35 to 61.5 bar. Nano-MH has good flame retardant and smoke suppressing properties. The samples added 60% nano-MH can reach UL94 FV-0 flame retardant rating. When nano-MH content is more than 40%, no smoke emits. With nano-MH content increases, the tensile strength, impact strength, elongation and M.F.R decreases, Young’s modulus increases.
The fresh-keeping function of molecularsieve added films on cherry tomatoes was discussed. It is indicated the molecularsieve added films have good fresh-keeping function. It can effectively control the respiration of cherry tomatoes. The Hβ-7 film has good fresh-keeping function.
Three-layered zeolite LTA-filled poly (vinyl alcohol) (PVA) composite membranes have been fabricated for water removal from highly concentrated ethanol solution by means of pervaporation. Higher separation factor and higher fluxes are both achieved after adding zeolite 3A, 4A and 5A. Through evaluating separation factor and permeation flux, separation performances of the composite membranes are elucidated in terms of the zeolite pore size and processing temperature.
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