EffectofPolymerizationTemperatureonCationicEmulsionProperties-文档资料

1、Effect of Polymerization Temperature on Cationic Emulsion Properties 【】The objective of this work was to analyze the effects of the polymerization temperature on the kinetic features (instantaneous and overall conversions) and colloidal characteristics mean particle diameter， stabilities in the semi

2、continuous seeded cationic emulsion polymerization of styrene and butyl acrylate. Azobis is obutyl amidine hydrochloride was used as an initiator.The surfactants wascetyl trimethyl ammonium chloride. The results showed that the final instant when the polymerization temperature of 85 emulsion highest

3、 conversion rate ， and the temperature of the emulsion particle size ， centrifugal stability is the best， 85 emulsion in the emulsion anti-dilution and acid salt stability also showed excellent stability. 0 Introduction It was known that there has a strong adsorption capacity between cationic latexp

4、articles with apositive charge and the substrate with the opposite charges. Cationic polymer has a wide range of applications in various industries in recent years ， because it can neutralize the negative charge on the material surface1-3.Semicontinuous seeded emulsion polymerization offers a great

5、degree of operational flexibility ， which permits both colloidal and polymeric characteristics to be controlled4-5. Many studies have been carried out to analyze the effect of the polymerization methods， emulsifier ， monomer ratio ， initiator in an emulsion polymerization， but a particular temperatu

6、re was setted. However， the effect of the reaction temperature in a cationic emulsion polymerization is reported in but a few cases.3，6 The aim of this work was to study the effect of the reaction temperature on the kinetic features( overall conversion ) and colloidal stability(mean particle diamete

7、r ， centrifugal stability， salt stability， dilution stability ， freeze-thaw stability ) of a semicontinuous seeded cationic emulsion polymerization of styrene (St) and butyl acrylate (BA). to study the effect of the reaction temperature on the growth of the particles starting from the same initial p

8、article number. In addition ， the stabilities of emulsion were studied deeply. 1 Experiment 1.1 Preparation of latex particles Figure 1 Reaction equation of emulsion polymerization We employed five PS latex samples.They were synthesized by semicontinuous seeded emulsion polymerization in different t

9、emperature using the same procedure. They were all performed under nitrogen with mechanical stirring at 250rmp.Deionized water（ 80g） and part of emulsifier were added into 250mL reactor and left for degassing approximately 5min .then part of distilled St and BA mixed monomer were added for pre-emuls

10、ification process about 30min at room temperature. A part of initiator（V50）was then added. Whent he reactor was heated at reaction temperature ， residual mixed monomerw ere added by dropwise. Residual emulsifier and initiatorwere added， after Completion of dropwise addition. After thermal insulation

11、 for 3h， the system was cooled to room temperature.7Preparation of cationic latex particles were prepared at different temperature by means of a semicontinuous emulsion polymerization with the recipe given in Table1. Preparation of cationic latex particles of the reaction ， such as figure 1.Table 1

12、Recipes Used in the Semicontinuous seeded Emulsion Polymerizations 1.2 Characterization of latex particles The instantaneous conversion was de ？ ned as the ratio of the polymer formed to the monomer fed at that time. The conversions was determined gravimetrically. The particle diameter dn was measur

13、ed by dynamic light scattering with an Auto Sizer Loc-FC-963 (Malvern Instruments ， UK) . The polydispersity of the particle diameters is calculated automatically. The density of latex particle was examined with density bottles. Centrifugal stability of polymer emulsion was determined by centrifuge

14、with 2000 r/min for 20 minutes.Electrolyte resistance stability was evaluated by adding some electrolyte. Stability of frost thawing was determined by freezing at-10 for 20h. 2 Results and Discussion 2.1 Polymerization Features Table 2 Properties of cationic emulsion Table 2 shows the X T values and

15、 dn were obtained by examination. The results shows that the higher polymerization temperature ， the smaller diameter. Wheni t reaches a certain temperature ， the particle size increases again. Wec an obtain the smallest diameter ( PS4). The reason is that reaction temperature is increased ， free ra

16、dical generating rate increased ， concentration of free radicals in the aqueous phase was increased. So， nucleation rate is increased. More and more latex particles can be generated.Therefore ， the particle size decreased in according to the polymerization temperature increased.8 We can also obtain

17、that the effect of polymerization temperature on the final conversion of emulsion from table 2. With the temperature increases ， the reaction rate is increased. So， conversion of emulsion is increased. That is because that ， with the temperature increases initiator decomposition was accelerated ， Sp

18、eed of chains growth rate constant is increased. Therefor ， final conversion of emulsion was increased.9 2.2 Emulsion stabilization ， centrifugal 2.2.1 Centrifugal stability Under the action of mechanical force stability is one of the important indicator for the centrifugal stability of all emulsion

19、 were very well except the PS5 ， which has a little precipitation. investigating emulsion is stable or not. It is showed that 2.2.2 Dilution stability As we known， dilutionstability of the emulsion will directly related to application performance. The result shows that the five samples have a excell

20、ent dilution stability.2.2.3 freeze-thaw stability All the cationic emulsions have formed cottony solid through reeze-thawed after 20h. It can be concluded that Freeze-thaw stability of cationic emulsion are poor. 2.2.4 Electrolyte resistance stability Electrolyte resistance stabilities of cationic

21、emulsion were determined by added H+ ， OH_ ，Mg2+， Respectively. The results are shown in Table 3. Table 3 H+ ， OH_ Mg2+ resistance stabilities of cationic emulsion Notes ： Transparent ， stabilityis good；- ：Slight precipitation ； *precipitation； +：Emulsion turbid Table 3 shows that the most stable emulsion is ， which was prepared at 85 ， especially the Salt resistance stability.Acid ， alkali ， and salts resistance stabilities of others cationic emulsion