Study On Preparation And Functional Modification Of Amphoteric Polyvinylamine

Polyvinylamine(PVAm)is a water-soluble polymer material with a large number of amino groups directly gratfed on the hydrocarbon skeleton,which endows the polymer with cationic properties.Moreover,the molecular chain length and charge density can be designed due to actual demands.Thus,polyvinylamine and its derivatives have a very broad application in water treatment,papermaking,biomedicine,separation technology,dyes,leather making and so on.In this paper,therefore,amphoteric polyvinylamine is used as a carrier for anchoring functional compounds for preparing new leather auxiliaries.This research mainly includes the following three parts:(1)Preparation and characterization of amphoteric polyvinylamine(A-PVAm)Firstly,poly(N-vinylformamide-co-acrylic acid)copolymer with different monomer ratio of N-vinylformamide with acrylic acid was prepared by free radical copolymerization reaction initiated by azodiisobutylamidine hydrochloride(V50),which was then hydrolyzed into A-PVAm.Their structures were characterized by infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy,and their isoelectric points,amino contents and thermal stabilities were studied respectivly.The results showed that Zeta potentials of the A-PVAm decreased with the increase of p H,and the isoelectric points of A-PVAm were 2.1,3.8,5.0,8.2 and 11.5,respectively.The increase of the isoelectric point of different A-PVAm was due to the increase of amino content.The amino contents increased gradually with the increase of NVF dosages,indicating that the A-PVAm was synthesized successfully.Thermogravimetric results showed that A-PVAm had good thermal stability.(2)The mass transfer and distribution of A-PVAm retanning agent in leatherA fluorescent tracer of FA-PVAm was prepared by using fluorescein 5-isothiocyanate reacted with A-PVAm for investigating the mass transfer and distribution of A-PVAm retanning agent in leather.The structure of FA-PVAm was characterized by infrared spectroscopy,and its thermal stability was characterized by TGA.The FA-PVAm is p H sensitive and exhibited higher fluorescence intensity at p H 8,and still had enough fluorescence intensity mixed with different leather auxiliaries.1%of FA-PVAm was added into A-PVAm retanning agents with different molecular weight,which were named as A-PVAm-L and A-PVAm-H respectively,and used in the retanning of wet blue.It was found that A-PVAm retanning agent penetrated mainly from the flesh side into the leather.60 min later,the retaning agent would distributed evenly in the leather.However,when the dosage of the retanning agent was not enough,it distributed mainly on the flesh side of the leather.When its dosage was above 15%,the retanning agent could distribute uniformly in the leather.Compared with A-PVAm-H,A-PVAm-L penetrated much easier into the leather from grain side.(3)The preparation and application of retanning-fatliquoring agent based on alkylenone dimerAlkylenone dimer(AKD)was emulsified by PVAm and A-PVAm respectively to prepare new retanning-fatliquoring agents,which were named as P-AKD and AP-AKD.The products were characterized and analyzed by infrared spectrum,Zeta potential,nano particle size tester and thermogravimetric analyzer,and their application properties were researched.The average diameter of AP-AKD and P-AKD was 411.9nm and 244nm,respectively.P-AKD had good 1:9 dilution stability,centrifugal stability and tannin resistance,while AP-AKD had good 1:9 dilution stability,tannin and chromium salt resistance.Both P-AKD and AP-AKD had good thermal stability.The application results show that the cationic retanning-fatliquoring agent P-AKD and amphoteric retanning-fatliquoring agent AP-AKD exhibited good thickening properties for leather.Compared with AP-AKD,P-AKD fixed the anionic dye better and endowed the leather higher waterproofness and waxy sensation,and the surface contact angle of sample retanned by P-AKD was as high as 152.5°.