Win Min Pva - G - Type Nipam Adhered To The Preparation Of The Graft Copolymer And Its Performance Study

Adhesives, a family of material most used in our daily lives and industry, have been widely applied in a large number of fields such as woodwork, architecture, packaging, vehicle, electronic industry, aviation, aerospace and cultural heritage conservation. An adhesive attraction is, namely, to bond two surfaces together through chemical or physical interaction. Thus, the adhesive material is between these two surfaces to realize the bonding attraction for them. Conventional adhesives are applied as a low-viscosity liquid and transform into a strong and tough solid that bond two surfaces together. Generally, this liquid-solid transformation is irreversible. Oftentimes, we require a bond or an adhesive that is not permanent, and the adhesive joint needs to be "debonded" at a pre-determined time. Therefore, an emerging area of adhesives research is the development of reversible adhesives. These adhesives enable facile debonding and separation of the bonded surfaces when the adhesion is no longer required. Uses for non-permanent adhesives, nonstructural applications include items, such as removable labels, surface protection films, easily placeable and removable notepaper, and bonding credit cards to mailers. Additionally, structural applications for non-permanent adhesives include tooling placement, prototyping, disassembly of parts for reuse and repositioning. In this thesis, we aim to prepare a novel thermosensitive membrane bearing tunable thermally induced adhesion property, and help to apply this new reversible adhesive film. Thus, there are two parts in our work as follows:1. A graft copolymer with thermosensitivity was prepared by graft copolymerization of monomer N-isopropylacrylamide (NIPAM) onto poly(vinyl alcohol)(PVA) in DMSO at40℃by using potassium peroxodisulfate (KPS) as an initiator. The structure and components of the copolymer were characterised by element analysis,1H NMR, FT-IR, DLS, DTG and DSC, respectively. The graft copolymer membranes were prepared by evaporating DMSO solution containing the graft copolymers. The lower critical solution temperatures (LCST) of the copolymer membranes were measured by DSC, which are all around31℃.2. The T-type peel adhesion strengths towards the paper and water contact angles of the graft copolymer membranes were determined at various temperatures. The results indicated that the membrane has an obvious change in adhesion and contact angle around31℃. Additionally, this temperature is almost same as the LCST of thermo-sensitive PNIPAM, regardless of the composition of the copolymers. Based on the SEM and EDS analysis of freeze-dried PVA-g-NIPAM graft copolymer membranes swollen in water at various temperatures, a mechanism for the thermally induced adhesion properties of the graft copolymer was proposed.