Renewable Matrix Polymers

Reptation assumes that the mobility of the matrix polymer plays no role in the relaxation of the tube constraint felt by a test molecule. However, if the matrix chains were very much more mobile than the test chain, additional lateral motion of the chain might be permitted by virtue of the constraining chains themselves moving away. This type of motion is called constraint release or tube renewal , and may be operative if some of the matrix chains are significantly shorter or intrinsically more mobile than the test chain (Green 1991, Composto etal. 1992). 

Polymer composites are also classified into renewable/nonrenewable polymer composites depending upon the nature of the polymer/matrix [1, 13, 16]. Figure 1.5 (b) show the classification of polymer composites depending upon the renewable/nonrenewable nature. Polymer composites in which both components are obtained from biorenewable resources are referred to as 100% renewable composites, while composites in which at least one component is from a biorenewable resource are referred to as partly renewable polymer composites 1, 13, 16]. Chapter 4 of the book presents a review on the state-of-the-art of partly renewable polymer composites with a particular focus on the hybrid vegetable/glass fiber composites. This chapter summarizes the hybridization effect on the properties of the final thermoplastic and thermoset polymer matrices... 

For detailed characterization and extensive studies of reactivity, multi-gram quantities are still needed and large-scale metal vapor synthetic routes are necessary. The equipment required for this is well-documented (4) and so will not be described in detail here. The principles are those of the Fluid Matrix Technique except that in order to accommodate 10-100 gram of polymer, the coreactant is contained within a rotating flask which serves to provide a continuously renewed film as metal atoms are produced under high vacuum. 

Lignin is the second most abundant natural polymer in the biosphere and the most abundant renewable aromatic material. It comprises 15-30% of woody plant cell walls, forming a matrix surrounding the cellulose. This encrusting matrix (1,2) significantly retards the microbial depolymerization of cellulose and thus lignin plays a key role in the earth s carbon cycle (1-3). 

Figure 20 Experimental relation between the tube renewal time Xrg and the reptation time Xg of the matrix for different molecular weights of various polymers [ data from ref 19].

---