Study On Preparation And Properties Of Novel Functional Poly(Vinyl Alcohol) Materials

Poly(vinyl alcohol)(PVA) is a kind of water-soluble polymer,which possess excellent chemical stability,acid resistance,base resistance,dry heat resistance, soluble in water and insoluble in most organic solvents and widely used in many fields.It's properties is between plastic and rubber and usually used as fiber and non-fibrous matters.Recently,because of increasing amount and decreasing profit of PVA,it is very urgent to discover novel functional PVA matters to make PVA sustainable development.This paper summarizes basic properties and conventional applications in every fields and give an introduction of novel functionalized PVA in recent years.Based on this,we propose that two methods to functionalize PVA are possible.The first way is to combine PVA and inorganic materials to form new PVA nano-composites to improve properties.The other is to use PVA as solid-phase synthesis support because PVA is very stability.Guided by this,four novel functional PVA matters were prepared in this paper and their properties was studied.The main conclusion is following:1.Firstly,silica nanoparticles were modified by vinyltriethoxysilane(VTEOS) and the amount of vinyl group was controllable by changing reaction conditions.The amount of vinyl group was up to 8.922 mmol/g.Secondly,these modified silica nanoparticles were copolymerized with vinyl acetate to form PVAc/silica nano-composites.Finally,PVA/silica nano-composites could be obtained by alcoholysis of PVAc/silica nano-composites.FT-IR and silica analysis were used to characterize PVAc/silica nano-composites.The properties of PVAc/silica nano-composites such as intrinsic viscosity and alcoholysis degree were changed even the amount of silica nanoparticles introduced into polymer was very small.At the same time,the thermal and mechanical properties of PVAc/silica nano-composites were improve greatly because of introduction of silica nanoparticles.For example,the onset of the thermal degradation temperature was shifted from 250.1℃to 261.1℃ and the glass transition temperature was improved from 71.0℃to 91.2℃.The Young's modulus increased from 36.3MPa to 52MPa and the tensile strength changed from 16.4MPa to 30.2MPa.2.Vinyl acetate was intercalated into kaolinite by a displacement method using dimethyl sulfoxide/kaolinite(Kao-DMSO) as the intermediate.The d(001) spacing of Kao-DMSO increased to 1.13 nm and Kao-VAc demonstrated the d(001) spacing was further enlarged to 1.44 nm.he intercalation rates(IR) of Kao-VAc was increased from 72%of Kao-DMSO to 78%.After,PVAc/kaolinite nano-composites was prepared via in situ free radical polymerization and PVA/kaolinite nano-compositeds was successfully obtianed by alcoholysis of PVAc/kaolinite nano-composites.The materials were characterized by FT-IR and XRD.The onset of the thermal degradation temperature was shifted from 240.1℃to 262.5℃and the glass transition temperature was improved from 61.2℃to 81.5℃.3.Firstly,highly crosslinked PVA beads were prepared by suspension crosslinking of linear PVA and epichlorohydrin.Then,ethylene oxide was grafted onto the PVA beads by anionic polymerization to form PVA-g-PEG resins.These resins were characterized by NMR,FT-IR,SEM,microscopy,DSC and TGA.All results indicated that this novel resin possess good solubility both in polar and no-polar solvents.At the same time,the functional group is up to 10 fold comparing to Tentagel and Argogel, which were popularly used in many fields.Last,scaling-up was carried out in the lab because this novel resin is so promising.4.The uniform PVAc beads with diameter between 1.8 mm and 2.0 mm were prepared via ascension polymerization and corresponding uniform PVA beads were obtained by methanolysis.The alcoholysis degree is up to 85%and the amount of hydroxyl group is 18 mmol/g.These beads were characterized by elements analysis, CP/MAS ¹³C NMR and FT-IR.