Preparation and Characterization of All-Cellulose Composites
Roppola, Jyri Tuomo Juhani (2017)
Roppola, Jyri Tuomo Juhani
2017
Materiaalitekniikka
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
This publication is copyrighted. You may download, display and print it for Your own personal use. Commercial use is prohibited.
Hyväksymispäivämäärä
2017-08-16
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201708241701
https://urn.fi/URN:NBN:fi:tty-201708241701
Tiivistelmä
The aim of this study was to develop test method for adhesion testing for cellulosic materials in order to explain phenomena occurring at an interface of two unlike surfaces. Based on results of the developed test method and understanding of composites, novel all-cellulose composite sandwich structures were designed, fabricated and mechanically tested. Most of the experiments were carried out at Technical Research Centre of Finland, VTT with collaboration with Tampere University of Technology.
Peel testing (T-peel) was chosen to gauge adhesion in the developed method. Single two-fold strips were prepared from chosen sample materials that were joined in a hot-press with either using distilled water, nanofibrillated cellulose (NFC) particle suspension as a processing aid. Commercial liquid PVA glue suspension was used as a reference adhesive. The adhesion tests suggest important correlation with fiber based material porosity and adhesion gained with NFC particle suspension: Bond strength between two adherents are improved with higher porosity. This is attributed to the observation that NFC particles penetrate into porous medium and coalesce onto network of fibers forming an auxiliary strengthening web of film within the macrostructure. Also, significant adhesion was achieved with using only water as a processing aid with several specimen types.
Four types of innovative novel all-cellulose composites were prepared: Sandwich structures in either a narrow beam or wide panel configuration were fabricated using nanofibrillated cellulose films and cellulose fiber foam. Films were used as cell wall and face material while foam used as core material. Beam configuration represented the side profile of the structure while the panels represented the longitude structure of the sandwich composite. The specimen made out of delignified NFC film and delignified fiber foam were referred to as white ACC (WACC). The term brown ACC (BACC) was used for the specimens made using partially delignified NFC film and CTMP fiber foam. The BACC specimens preformed significantly better than the WACC specimens in flexural three-point bending testing. The ACCs were also compared to specimen series made using corrugated board (CB) designed for hazardous goods packaging.
Future work should be directed to prepare more elaborate ACC configuration and to testing of these types of composites. Also, the study of the effect of temperature on adhesion in laminate forming is highly recommended based on this work.
Peel testing (T-peel) was chosen to gauge adhesion in the developed method. Single two-fold strips were prepared from chosen sample materials that were joined in a hot-press with either using distilled water, nanofibrillated cellulose (NFC) particle suspension as a processing aid. Commercial liquid PVA glue suspension was used as a reference adhesive. The adhesion tests suggest important correlation with fiber based material porosity and adhesion gained with NFC particle suspension: Bond strength between two adherents are improved with higher porosity. This is attributed to the observation that NFC particles penetrate into porous medium and coalesce onto network of fibers forming an auxiliary strengthening web of film within the macrostructure. Also, significant adhesion was achieved with using only water as a processing aid with several specimen types.
Four types of innovative novel all-cellulose composites were prepared: Sandwich structures in either a narrow beam or wide panel configuration were fabricated using nanofibrillated cellulose films and cellulose fiber foam. Films were used as cell wall and face material while foam used as core material. Beam configuration represented the side profile of the structure while the panels represented the longitude structure of the sandwich composite. The specimen made out of delignified NFC film and delignified fiber foam were referred to as white ACC (WACC). The term brown ACC (BACC) was used for the specimens made using partially delignified NFC film and CTMP fiber foam. The BACC specimens preformed significantly better than the WACC specimens in flexural three-point bending testing. The ACCs were also compared to specimen series made using corrugated board (CB) designed for hazardous goods packaging.
Future work should be directed to prepare more elaborate ACC configuration and to testing of these types of composites. Also, the study of the effect of temperature on adhesion in laminate forming is highly recommended based on this work.