In order to expand the application range of polyethylene and reduce the cost, it can be modified with inorganic fillers, such as calcium carbonate filled into the polymer. However, this system faced more severe die-out during extrusion than pure resin. Die precipitation can affect the extrusion process, ranging from surface defects in the material to production interruptions or product scrapping.
Polyethylene film is a more important product in extrusion materials. Li Li et al. explored the effect of different additives on the improvement of polyethylene/calcium carbonate system die precipitation, and further conducted research on the rheological viscosity and melt strength of the material. Exploration, to a certain extent, provides guidance for the solution of this industry problem. polyethylene wax manufacturers in india
(1) The die precipitation of the highly filled system at 30min is ranked as follows: calcium stearate < silicone < no additive system < polyethylene wax, the smaller the precipitation, the better the precipitation improvement effect. Elemental analysis was carried out on the above-mentioned precipitates, mainly including carbon, calcium and oxygen elements. It can be seen that the main components should be calcium carbonate and resin, indicating that the precipitation is mainly due to the incompatibility of calcium carbonate filler and resin. caused by melt fracture and accumulation over time.
(2) The study of melt behavior such as viscosity and melt strength of several systems shows that on the one hand, the lubricating effect of calcium stearate reduces the viscosity of the material, and on the other hand, by enhancing the melt strength of polyethylene and calcium carbonate composites, Reduce melt fracture, thereby improving material precipitation; silicone can only improve precipitation to a certain extent through lubrication, and polyethylene wax has a great influence on melt strength and will increase die precipitation.
The current acrylic polymer thickener using more methods is a semi-continuous emulsion polymerization method, which has good polymerization stability, emulsion product particle size uniformity. Under acidic conditions, the polymer wax is mainly dispersed in water as latex particles; under alkaline conditions, the carboxyl groups on the polymer backbone ionize and the molecular chains stretch, while its hydrophobic side chains can form a physical cross-linked network structure through hydrophobic linkage, resulting in significant thickening and thixotropy.
In the construction process, it can prevent the paint from hanging and ensure the paint has good construction performance.
Cellulose ether (methyl cellulose, hydroxypropyl methyl cellulose, sodium carboxymethyl cellulose, hydroxyethyl cellulose)
Natural polymers and their derivatives (starch, gelatin, sodium alginate, casein, guar gum, shell gum, gum arabic, xanthan gum, soy protein gum, natural rubber, lanolin, agar).
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