外文翻譯--含有粘土的高吸水性復(fù)合材料的制備與性質(zhì)（英文）

1、Synthesis and properties of clay-based superabsorbent compositeAn Li, Aiqin Wang *Centre for Ecological and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, PR ChinaRec

2、eived 13 August 2004; received in revised form 10 October 2004; accepted 30 January 2005 Available online 8 March 2005AbstractA novel superabsorbent composites based on acrylic acid, acrylamide, and inorganic clay minera

3、l-attapulgite were synthesized through a solution polymerization to improve water and saline absorbencies. The superabsorbent compo- site was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravime

4、tric analysis (TGA) and scan- ning electron microscopy (SEM). The effects of saline solutions, amount of initiator, crosslinker and attapulgite on the water absorbency of superabsorbent composites were investigated. The

5、water retention test of superabsorbent compo- sites were also carried out. The superabsorbent composite exhibited improved water and saline absorbencies compared with that of crosslinked poly(acrylic acid–co-acrylamide)

6、superabsorbent polymer. The water absorbency of the super- absorbent composite synthesized under optimal synthesis conditions with an attapulgite content of 10% reaches more than 1400 g H2O/g and 110 g H2O/g in distilled

7、 water and 0.9% NaCl solution, respectively. ? 2005 Elsevier Ltd. All rights reserved.Keywords: Acrylic acid; Acrylamide; Attapulgite; Superabsorbent composite; Water absorbency1. IntroductionSuperabsorbent polymers are

8、loosely crosslinked net- works that can absorb a large amount of water in a short time and retain water under pressure. Although super- absorbent polymers have been abundantly used in the disposable diaper industry for t

9、he past 30 year, their applications are still being expanded to many fields including agriculture and horticulture [1,2], sealing com- posites [3], artificial snow [4,5], drilling fluid additives [6], medicine for drug d

10、elivery system [7–9] and so on.Recently, the preparation of polymer/clay superab- sorbent composites has received great attention because of their relative low production cost and high water absorbency [10,11]. The prepa

11、ration and the swelling behaviors of poly(acrylic acid)/attapulgite superabsor- bent composite have been reported in our previous study [12,13]. In which, we know that the water absorbency of the poly (acrylic acid)/atta

12、pulgite superabsorbent composite in distilled water was greatly improved as compared with crosslinked poly (acrylic acid) superab- sorbent polymer, but the water absorbing ability of superabsorbent composite in saline so

13、lutions only slightly increased. It is well known that the water absorb- ing ability of a superabsorbent in saline solution is also very important for many applications. Therefore, the synthesis of new superabsorbent com

14、posite which has0014-3057/$ - see front matter ? 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.eurpolymj.2005.01.028* Corresponding author. Tel.: +86 931 4968118; fax: +86 931 8277088. E-mail address: aqwang@ns.l

15、zb.ac.cn (A. Wang).EUROPEAN POLYMER JOURNALEuropean Polymer Journal 41 (2005) 1630–1637www.elsevier.com/locate/europoljsamples were performed on a Perkin-Elmer TGA-7 thermogravimetric analyzer (Perkin Elmer Cetus Instru-

16、 ments, Norwalk, CT), with a temperature range of 25– 700 ?C at a heating rate of 10 ?C/min using a dry nitrogen purge at a flow rate of 50 ml/min. The morphology of the dried samples was examined using a JSM-5600LV SEM

17、instrument (JEOL, LTD) after coating the sample with gold film.3. Results and discussion3.1. Effect of initiator contentFig. 2 shows the effect of the initiator content on the water absorbency of superabsorbent composite

18、. The water absorbency increases as APS content rises from 0.2% to 1.0% and decreases with further increase in the content of APS. The relation between the average ki- netic chain length (V) and concentration of the init

19、iator in free-radical polymerization is given by the following equation [14]:V ¼ 1=2kpðfkiktÞ?1=2½I??1=2½M? ð2Þwhere kp, ki and kt are the rate constants for propaga- tion, initiator, a

20、nd termination, respectively; f, the effi- ciency of initiation by the initiator; and [I] and [M], the initial concentration of the initiator and monomer, respectively. According to Eq. (2), the molecular weight in free-

21、radical polymerization decreases with increase of the initiator concentration. With decrease of the mole- cular weight, the relative amount of polymer chain ends increase. As mentioned in previous study [15], the poly-me

22、r chain ends do not contribute to the water absor- bency. Therefore, this is responsible for the decrease in the water absorbency with increase of the initiator con- tent. When the content of APS is below the optimum val

23、ues, the swelling capacity of superabsorbent compos- ite is also decreased. This may due to a decrease in the number of radicals produced as the content of APS de- creases. The network cannot be formed efficiently with a

24、 few numbers of radicals in free-radical polymerization reaction, which results in the decrease of the water absorbency [12].3.2. Effect of crosslinker contentThe effect of crosslinker content on water absorbency is show

25、n in Fig. 3. It can be seen from Fig. 3 that the water absorbency decreases with the increase of cross- linker content from 0.2% to 1.0%. The relation between the swelling ratio and network structure parameter for the sw

26、elling of ionic network was given by Flory [16], usually used as the following two equivalent equation:Q5=3 m ¼ ½ði=2V uS1=2Þ2 þ ð1=2 ? X 1Þ=V 1?=ðV e=V 0Þ ð3ÞQ5=3 m

27、 ¼ ½ði=2V uS1=2Þ2 þ ð1=2 ? X 1Þ=V 1?ðMc=qpÞ? ð1 ? 2Mc=MnÞ?1 ð4Þwhere Qm is swelling ratio; i/Vu, the concentration of fixed charge referred to the unswolle

28、n network; S, the io- nic concentration in the external solution; (1/2 ? X1)/V1, the affinity of the hydrogel with water;Ve/V0, the cross- linked density which refers to the number of effectively crosslinked chains in un

29、it volume; Mc, the average0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 200400600800100012001400Water Absorbency (g/g)APS Content (wt%)Fig. 2. Effect of initiator content on water absorbency of superabsorbent composite

30、 in distilled water: reaction temper- ature, 70 ?C; 40% neutralization degree of AA; molar ratio of AM to AA is 0.51, weight ratio of crosslinker and attapulgite in the feed is 0.2% and 10%, respectively.0.2 0.4 0.6 0.8

31、1.02004006008001000120014001600Water Absorbency (g/g)MBA Content (wt%)Fig. 3. Effect of crosslinker content on water absorbency of superabsorbent composite in distilled water:reaction tempera- ture, 70 ?C; 40% neutraliza