I am developing a bio-based material. In order to increase it's strength I decided to blend it with cellulose fibres. The problem is the cellulose fibres don't spread evenly and uniformly and instead they tend to cluster in one part of the material. I wanted to look to the polymer structure of both substances (cellulose, and the bio-based material) and see if I could find the reason for this. I was wondering what should I look into in order to find a solution.
When you blend two polymers, those must be miscible thermodynamically. Unfortunately, cellulose fiber being insoluble under normal conditions, you need to consider the surface structure of the fiber, which is covered with hydroxyl groups if you cleaned the fiber well (otherwise it is covered in part by hemicellulose and lignin which also contain hydroxyl groups but with different non-hydroxyl portion of the polymers). Thus, if you want the cellulose fiber to disperse well, you need to choose hydrophilic polymers, including hydrogen bond acceptors. Ethers, esters and amines containing polymers are good for this. Polymers, such as poly(vinyl alcohol), poly(epsilon caprolactone), poly(ethylene ether), nylon, are a good start. You can evaluate the miscibility (thermodynamic term), but not compatibility (engineering term), by calculating the solubility parameter of cellulose and the polymer you want to use. When the solubility parameter is pithing ± 0.5, the polymer will disperse the fiber well.
Hello Irene Salom.
Pay attention to the charge of polymers. As far as I understand, in order to obtain high-quality mixing, it is necessary that the materials have a comparable particle size. If you are interested in cellulose fibers, then try this: cellulose fibers and melt or polymer solution. In this case, polymer adhesion on cellulosic fibers will be a key issue.
When you blend two polymers, those must be miscible thermodynamically. Unfortunately, cellulose fiber being insoluble under normal conditions, you need to consider the surface structure of the fiber, which is covered with hydroxyl groups if you cleaned the fiber well (otherwise it is covered in part by hemicellulose and lignin which also contain hydroxyl groups but with different non-hydroxyl portion of the polymers). Thus, if you want the cellulose fiber to disperse well, you need to choose hydrophilic polymers, including hydrogen bond acceptors. Ethers, esters and amines containing polymers are good for this. Polymers, such as poly(vinyl alcohol), poly(epsilon caprolactone), poly(ethylene ether), nylon, are a good start. You can evaluate the miscibility (thermodynamic term), but not compatibility (engineering term), by calculating the solubility parameter of cellulose and the polymer you want to use. When the solubility parameter is pithing ± 0.5, the polymer will disperse the fiber well.
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