Polypropylene neutron study

There is an enormous body of work on quasielastic neutron scattering from polymers [1,2]. There is a smaller literature on neutron vibrational spectroscopy of polymers but this has had a significant impact on the characterisation of these materials. Crystalline or semi-crystalline polymers are the most important class of polymers commercially. The most-studied and technologically most important of these is polyethylene and this will be considered in some depth and we will highlight the use of the n-alkanes as model compounds ( 10.1.2). We will then see how these concepts can be transferred to polypropylene ( 10.1.3), nylon ( 10.1.4), and conducting polymers ( 10.1.5). Non-crystalline polymers ( 10.2) have been much-less studied by INS. As examples, we will consider polydimethylsiloxane ( 10.2.1) and advanced composites ( 10.2.2). 

Small-angle neutron scattering (SANS) studies on melt crystallized linear polyethylene, isotactic polypropylene, and poly(ethylene oxide) have shown that deuteriated molecules in a hydro-chain matrix have the same radius of gyration, and so molecular conformation, as in melt. This is evidently inconsistent with a regular adjacent re-entry folded chain lamellae. Recently Stamm et in comparing the scattering of neutrons at intermediate angles, of... 

Jones et al. [35] used small-angle neutron scattering to study the chain dimension of syndiotactic polypropylene and found that the s-PP chain is substantially larger than that of i-PP. This implies that the s-PP molecule is stiffer than that of i-PP, which results in significant differences in the rheological and thermodynamic behavior of the two forms [35, 36]. The effect of tacticity on rheological properties is discussed in Chapter 5. 

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