Preparation And Properties Of Coating Material For Fertilizer With Water-retention And Slow-release

Traditional acrylate water-retaining material cost is high,the performance is single,the absorption rate is low,the water retention ability is poor,etc.How to reduce the cost,improve the properties of materials is the key factor in the development of water retaining film materials.The surface of cheap and fine clay material often has a large number of Si(Al)-OH structure,and in the interior there are a lot of metal ions.The introduction of clay into the polymer structure can improve the performance of raw materials,increase the economic benefit and expand the profit margins.Herein,a series of composite water-retaining materials were successfully synthesized by means of aqueous solution polymerization,using the redox initiation system of potassium persulfate and sodium sulfite,with acrylic acid(AA)and acrylamide(AM)as reaction monomers,N,N-methylene double acrylamide as crosslinking agent,glycerol as the plasticizer,where modified montmorillonite(OMMT),montmorillonite(MMT),and Kaolin clay(Kaolin)were used.In order to reduce costs,improve performance of materials for the purpose of study on relationship between synthetic factors and performance,and then coated fertilizers with water-retention and slow-release were studied.Finally,the synthetic materials and coatings were characterized by FTIR,TGA and SEM.The main conclusions are as follows:(1)Considering the cost and performance of composite water retention material,the best synthetic formula is: the monomer ratio is m(AA):m(AM)=3.5:1,the neutralization degree was 70%,the dosage of initiator was 1%,the dosage of crosslinking agent was 0.04%,the dosage of glycerol was 15%,the dosage of montmorillonite was 20%.The water absorption capacity of the composite water retaining material in the salt solution decreased with the increase of the ionic concentration,and in the chloride solution with the same cation concentration,the influence order of each ion was Fe3+> Ca2+>Na+>K+?(2)With the infrared(FTIR)and thermogravimetric(TG-DTG)method to characterize the composite material.FTIR showed that the combination of clay and polymer was not a simple mix,but the hydroxyl(-OH)structure on the surface of clay reacted with the carboxyl group(-COOH)of the acrylic acid.Decomposition temperature of P(AA-AM)/clay composite increased by seen from TG-DTG,implying that clay made the composite material more heat-resistant.Thus the three processes of the composite of the clay and the reaction material are as follows: the esterification reaction;the initiation reaction;and the establishment of the hydrogen bond structure.(3)The preparation of coated fertilizer with water-retention and slow-release was realized by using the self-made spraying equipment,and coated liquid of water absorbent material.In the aspect of the slow-release properties,water retention capacity and water holding capacity of soil,the related performance tests showed that the performance of P(AA-AM)/clay coated fertilizer with water-retention and slow-release was better than that of P(AA-AM)coated fertilizer with water-retention and slow-release.(4)The IR spectra and SEM images of the films showed the existence of the water holding film,and the appearance of pores,lamellae and islands in the SEM film structure explains the reason of the high liquid absorption.