Cellulose polyblends

Cellulose can also blend with natural or synthetic polymers to produce adhesives. The recent development of new cellulose solvents(iO), such as lithium chloride/dimethyacetamide solvent, dinitrogen tetroxide/dimethylformamide solvent, dimethyl sulfoxide/paraformaldehyde solvent, have provided the potential to produce uniform cellulose polyblends. 

Cellulose constitutes a ubiquitous and renewable natural material that has great potential for chemical conversion into high-quality adhesive products. The resurrection of research and development of cellulose derivatives, such as cellulose esters and ethers, cellulose graft-copolymers, and cellulose polyblends, has instituted new avenues for adhesive applications. There is little doubt that new solvent systems for cellulose have created the potential of developing uniform cellulose products with superior properties for adhesive applications. 

Cellulose is an old polymer with new industrial applications. The derivatization of cellulose has opened up tremendous production and marketing possibilities for the adhesives industry. Various important adhesives have been derived from cellulose ethers. The structure and molecular size of cellulose and their influence on swelling and solubility are important considerations in the preparation of cellulose derivatives for adhesive applications. Modern cellulosic adhesives derived from grafted copolymers and polyblends are also proving very useful. 

Polyblending of cellulose and polyethylene fibers (Morgan, 1961). The resultant paper, which comprises long, soft polyethylene fibers intertwined with the traditional cellulose, can be heat-sealed to a substrate (such as a steel can), and has improved properties, particularly wet strength. Alternatively, a sandwich of polyethylene fibers layered between two cellulose mats may be used such a paper exhibits considerable water resistance. 

As a polyester, PHB can partake in many of the hydrogen-bonding type of specific interactions with other functional additives that lead to partial miscibility and compatibility. For example, the miscibility of polyesters with chlorinated polymers, polyamides, polycarbonates, cellulose derivatives and other functional polymers is well documented,and PHB is no exception to this general observation. However, these interactions are dominated by the tendency to self-crystallize with exclusion of the additive to the amorphous phase. For example, an 80/20 melt compounded and injection-moulded sample of PVC/PHB polyblend appears initially to be exceptionally tough with the PHB acting as a polymeric plasticizer. The presence of the PVC retards but does not stop crystallization of the PHB at room temperature and the material eventually becomes brittle. Under extreme circumstances, the PHB phase can actually achieve almost 100% crystallinity within the blend, as determined by X-ray analysis and DSC. Thus, plasticized formulations and polyblends involving PHB itself are limited to relatively low levels of additive because only the minor amorphous phase of the biopolymer is involved in the interaction. Even so, some plasticizers have been proposed for PHB. ... 

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