Preparation And Properties Of Hydroxyl Polyaspartic Acid/Amino-modified Bentonite Composite Superabsorbents

Polyaspartic acid(PAsp)superabsorbnet resin is a kind of innoxious,innocuity and biodegradable novel functional polymer materials which has been widely used in many fields.However,the application of PAsp with pure component is extremely limited in use.This attributed to its single property,poor performance of salt tolerance,low gel strength and high production cost and so on.Thus,in this paper,a novel hydroxyl polyaspartic acid/Amino-modified bentonite(HPAsp/AMB)composite superabsorbent has been obtained by introducing AMB and ethanolamine by inverse suspension polymerization using polysuccinimide(PSI)and aminatified bentonite(AMB)as raw material,ethanolamine as modifiers,hexamethylenediamine as crosslinking agents.In order to make the AB more effective composite with PSI,AB is obainted in this paper as follows.At first,cation-exchange agent cetyl trimethyl ammonium bromide(CTAB)is intercalated into the layer of bentonite.Then the intercalated bentonite is modified by silane coupling agent 3-triethoxysilylpropylamine(KH550)in order to introduce the amino groups on the surface of bentonite,which can increase its compatibility with polymer(PSI).Infrared spectroscopy(FTIR),X-ray diffraction spectrum(XRD)and scanning electron microscopy(SEM)of clay before and after intercalation and modification could befound that:①The FTIR shows that CTAB and KH-550 has been successfully composited with bentonite;②The XRD shows that compared with bentonite,the layer space of intercalated bentonite and AMB is increased which indicates CTAB and KH-550 was intercalated into the layer of bentonite;③From scanning electron microscopy(SEM)images after intercalated and amino-modified of bentonite,their particles decrease,their specific surface area increase,and their dispersion is better.In order to improve the properties of water absorbency,salt resistance and water-retaining of polyaspartic acid superabsorbent and cut production cost,AMB and ethanolamine are introduced into PAsp by inverse suspension polymerization in order to synthesize hydroxyl polyaspartic acid/amino-modified bentonite(HPAsp/AMB)composite superabsorbent resin beads.The particle shapes of superabsorbents are observed by optical digital microscope,and then discuss the content of dispersant and crosslinking agent effects on the particle shape of the resin.The results show that the size of resin beads decreases with the increasing of dispersant content but increases with the increasing of crosslinking agnet content;when the content of dispersant and crosslinking agent,the stirring rate,the volume ratio of oil phase and non-polar phase,the contentration of PSI in DMF solution are 2wt%and 2.5mol%,250 rpm,3:1,20%,espectively,the size of the particles formed in inverse suspension system were uniform and mainly unattached to each other.The influences of dispersant quantity,cross-linker quantity,AB quantity and ethanolamine quantity on the capacity of the water absorbency and salt absorbency of composite superabsorbents were discussed by single factor experiment.Results show that the water absorbency of the composite superabsorbent firstly increases and then decreases with the dosage of dispersant,crosslinking agent,amino-modified bentonite and ethanolamine.Then the optimum condition is the content of dispersant,crosslinking agent,aminatified bentonite and ethanolamine are 2wt%,2.5mol%,3wt%and 15mol%,respectively.The salt resistance,pH sensibility and temperature response of hydroxyl polyaspartic acid/amino-modified bentonite(HPAsp/AMB),polyaspartic acid(PAsp),hydroxyl polyaspartic acid(HPAsp)and polyaspartic acid/amino-modified bentontite(PAsp/AMB)are studied and compared,respectively.The results indicated that the water absorbency properties of HPAsp/AMB superabsorbent composites are obviously improved as a function of pH,temperature and concentration of inorganic salt.The SEM characterization of these superabsorbents revealed HPAsp/AMB and PAsp/AMB shows a more porous surface than that of HPAsp and PAsp which means the AMB has some influence on water absorbency properties of corresponding composite superabsobents.