TY  - EJOU
AU  - Konovalov, Dmitry S. 
AU  - Saprykina, Natalia N. 
AU  - Zuev, Vjacheslav V. 

TI  - Enhancing Mechanical Properties of Biobased Polyurethane Composites Using Birch Flour and Diatomite Fillers
T2  - Journal of Renewable Materials

PY  - 2025
VL  - 13
IS  - 10
SN  - 2164-6341

AB  - In this study, the polyurethanes (PU) were synthesized from 4,4<sup>′</sup>-methylene diphenyl diisocyanate and biobased ethoxylated castor oil or one mixture of ethoxylated and neat castor oil by direct mixing method. Utilization of ethoxylated castor oil increases the tensile strength of PU up to 2.75 times (from 3.2 to 8.8 MPa), compared to PU based on neat castor oil. The PU composites filled with birch flour, diatomite, and their mixture were prepared using a homemade dissolver with a cutter-shaped attachment at a speed of 1500 r min<sup>−1</sup>. The tensile strength of PU composites filled with birch flour increases up to two time at loading 5–30 wt.%. Application of combined birch flour/diatomite additives has similar effect. The tensile strength of PU composites based on one to one mixture of ethoxylated and neat castor oil and filled with birch flour or combined birch flour/diatomite additives increases sharply up to 16–17 fold (up to 18.1 MPa). The birch flour and diatomite well soaked polymer matrix. The main factor determining mechanical performance is the morphology of PU samples and composites. Formation of ordered lamella-like structure of the amorphous phase of PU matrix leads to an increase in mechanical performance and glass transition temperatures. The formation of a disordered unstructured soft phase of starting PU leads to a decline of these functional properties.
KW  - Birch flour; diatomite; polyurethane; composites; mechanical performance; morphology

DO  - 10.32604/jrm.2025.02025-0079