Preparation And Characterization Of Microporous Polymer Microspheres Inside

In this paper,polymer microspheres with microporous structure in internal are prepared by suspension polymerization for acid mist suppression.Firstly,The porogen is dispersed into water phase dissolved disperse agent,mechanical stirring and heating to arrived we need,then the styrene-divinylbenzene(St-DVB)dissolved azodiisobutyronitrile(AIBN)is added to reaction system in a way of adding style,and gradually move to the surface of porogen micro-droplets duo to driving force of lipophilicity of monomer,In the process of reaction,cross-linked polystyrene microspheres with microporous structure in internal can be fabricated because of phase separation between polymer and porogen.The polymer microspheres size is range from 50 to 200?m,having properties with low density,surface impermeable and mechanical strength.The primary contents of this paper include:(a)The effect of stirring speed,concentration of dispersant and volume ratio between oil and water phase on particle size distribution.(b)The effect of the dosage of porogen and crosslinking agent,the rate of adding,the types of porogen,the volume ratio between porogen and monomer&crosslinking agent,the volume ratio between monomer and crosslinking agent,and the dosage of initiator on external morphology and internal structure of polymer microspheres.(c)The optimization of the preparation of polymer microspheres with microporous in internal and effect evaluation of suppressing acid mist.The main conclusions are shown as follows:(1)Stirring speed,concentration of dispersant and volume ratio between oil and water phase have great effect on particle size distribution.To meet the requirement of acid mist suppression,the particle size distribution of polymer microspheres should range from 50 to 200?m,Considering the three factors effected particle size distribution,the optimum conditions are shown as follows:the stirring speed is 550rpm,the concentration of dispersant is 1%,the volume ratio between oil and water phase is 1:5.(2)When the dosage of the porogen is less than 1.3 times of the volume of the monomer,the prepared microspheres are regular spherical and the inside is solid.When the dosage is 1.3 times larger than or equal,the surface of the prepared microspheres will be sunken and the internal is cavity structure.As the volume ratio of styrene and divinylbenzene decreases,the surface of the prepared polymer microspheres becomes smoother from many folds and the internal structure does not change much.The effect of monomer dropping rate on the external morphology and internal structure of the prepared polymer microspheres is not obvious.If the solvent with good compatibility with the polymer is used as the porogen,the surface of the prepared microsphere is relatively smooth and the interior is denser;if the poor solvent of the produced polymer or the solvent with poor compatibility is used as the porogen,the surface of the prepared polymer microspheres form wrinkles or surface collapses to form microporous or cavity structures.With the increase of the amount of initiator,the prepared polymer microspheres collapsed from the spherical,and the wrinkles on the surface gradually decreased.(3)When the volume of the porogen is less than 0.3 times of the volume of the monomer,or the density of the microspheres prepared by using cyclohexane,dimethyl carbonate and diethyl carbonate as the porogen is greater than lg/cm3;The density of the polymer microspheres prepared in other conditions is less than lg/cm3.the polymer microspheres prepared in optimal condition had a good effect on the suppress of volatilization of hydrochloric acid at a concentration of 3%when the thickness of polymer microspheres are about 3cm.