Textile Applications of Cellulose Nanowhisker Reinforced Thermo-water Responsive Polyurethane Composite Structure


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Korkmaz Memiş N., Kaplan S.(Executive)

Project Supported by Higher Education Institutions, 2017 - 2020

  • Project Type: Project Supported by Higher Education Institutions
  • Begin Date: May 2017
  • End Date: March 2020

Project Abstract

Shape memory polymers (SMPs) are among very important smart materials having the capability to return their original (permanent) shapes from a temporary shape under appropriate external stimulus such as heat, light, electric field, magnetic field, pH or water/moisture. Nowadays, most studies of SMPs focus on thermal induced structures because of their wide possible applications in different fields. Among the thermal induced SMPs, segmented shape-memory-polyurethanes (SMPUs) have gained much popularity with the knowledge database they have, their wide range of transition temperatures, ease in shape ability, and their capability to include wide range of additives. However, biomedical and tissue engineering applications of thermal induced SMPs are limited because their switching temperature does not fall completely within the range of room temperature to body temperature. For this reason, in recent years there is a need for development of polymeric structures with sensitive shape memory effect against thermal stimuli. At this point, water-induced SMPs exhibiting lower transition temperatures with water in the polymer matrix has attracted attention. In such SMPs, the water molecules penetrate into the amorphous region of the polymer and enable shape recovery at a lower temperature with disrupting intermolecular hydrogen bonds, plasticizing, and reducing the glass transition (Tg) temperature. However, water-induced SMPs have some disadvantages such as low elastic modulus, stiffness and strength properties, long shape recovery time due to slow diffusion process and difficulty in removing water absorbed by the polymer. In recent years, scientists have focused polymeric composite/nanocomposite materials to obtain water-induced SMPs because of the complexity of the chemical molecular design and the ability of water-induced structure according to the structural properties of the polymer segments.

 

Cellulose nanowhiskers (CNW) have nearly perfect crystalline structures where the cellulose chains are arranged compactly with strong hydrogen bonding interactions. CNW has attracted interest in recent years as a reinforcement filler because of its high stiffness of up to around 138-200 GPa, high crystallinity, strength, low density, renewable, biodegradable and unique surface chemistry. In addition to the mentioned properties, the water-induced shape memory effect can be obtained depending on the percolation formed by hydrogen bonds which can be reversibly regulated by water molecules.

 

The aim of this study is to produce and chemical/mechanical analysis of polymeric nanocomposite films featuring a heterogeneous-twin-switch shape memory effect (thermal and water responsiveness simultaneously). Design of composite structures was selected due to the complexity and application difficulty of chemical molecular design of materials with water/moisture sensitive memory effect by paying attention to the points mentioned. Polymeric nanocomposite films are planned to be prepared using cellulose-nanowhiskers as reinforcement and segmented shape-memory-polyurethane as matrix in the production of the textile materials having both thermal and water/moisture sensitive memory effect. The polymeric nanocomposite films will have the thermal-induced shape switchable effect originally existing in the polymer matrix and is planned to simultaneously possess water-induced shape memory effect due to the percolation network of the cellulose whiskers whose hydrogen bonding can be regulated by water reversibly. Also, textile applications in the forms of fiber and coating/film in various fabric structures of cellulose nanowhisker reinforced polyurethane composite structure will be investigated in this study. In addition to standard polymer characterization tests, physical, mechanical, water absorption and shape memory tests with thermo-aqueous programming will be conducted. Literature survey indicated that there is a limited number investigation about the polyurethane cellulose-nanowhisker nanocomposite films featuring a heterogeneous-twin-switch shape memory effect. From this point, it is thought that results of this study about production and performance analyses of textile materials produced with multifunctional shape memory polyurethane reinforced by cellulose-nanowhiskers will contribute to both national and international literature.