Structure-Property Relationship of Thermoplastic Polyurethane Composites with Inclusion of Modified Microcrystalline Cellulose

초록

With growing interest of eco-friendly polymer composites, many researchers employed cellulose as a filler for polymer composites. In particular, microcrystalline cellulose (MCC) obtained by acid treatment of cellulose has advantages such as high crystallinity and mechanical properties originating from strong intermolecular hydrogen bonding. However, too strong interaction among MCCs can lead to aggregation of fillers in polymer composites, reducing the interfacial areas and reinforcement effects between the polymer matrix and filler. In this research, we employed three different chemically modified microcrystalline cellulose (m-MCC) where hydroxyl groups of MCC were substituted by either methyl (-CH3) or hydroxypropyl (-CH2CH(OH)CH3) groups: (1) low substitution degree with methyl group (HP-0), (2) medium substitution degree with methyl and hydroxypropyl groups (HP-low), and (3) high substitution degree with methyl and hydroxypropyl groups (HP-high). Three different types of m-MCCs were compounded with ester type thermoplastic polyurethane (TPU) by an extrusion process. As the chemical substitution of hydroxyl group by methyl or hydroxypropyl functional groups can reduce the number of hydrogen bonding sites or increase m-MCC intermolecular distances, both crystallinity of m-MCCs and polymer-filler interaction can also be manipulated. In this presentation, we will discuss structure-property relationships of TPU-MCC composites with focuses on correlation of crystallinity and dispersion of m-MCC with mechanical properties of the TPU-MCC composites.