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Poly(l-olefin)s from poly(l-butene) up to poly(1-octadecene) have been characterized. The melting point was measured by Differential Scanning Calorimetry (DSC-1B) and dilatometry, the specific volume and volume expansion coefficient by dilatometry, and the unperturbed chain dimension by intrinsic viscosity at near theta conditions. A trend is confirmed for melting points and revealed for expansion coefficients of first a decrease with increasing side-chain length in the polyolefins, followed by an increase with further increase in length. The minimum is near poly(1-hexene) and poly(1-heptene). The specific volume of the polytl-olefin) series exhibits a maximum around this same composition. The minima in melting point and thermal expansion coefficient and the maximum in specific volume are discussed in terms of chain-to-chain packing density. It is suggested that packing density is a minimum in this region. Two melting points were found for each of several higher poly(lolefin)s from poly(1-tridecene) up to poly(l-octadecene). It is found that the theta temperatures of the poly(l-olefin) series, as measured in two solvents, anisole and cyclohexanone, exhibit a minimum at poly(l-pentene). However, the characteristic ratios and the steric factors increase with increasing side-chain length for the entire series of measured poly(1olefin)s.

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SynopsisThe steady-state and dynamic melt rheology for a series of poly( 1-olefins) has been investigated. The series includes poly(1-butene), poly(1-hexene), poly(1-heptene), poly(1-octene), poly(1-undecene), poly(1-tridecene), poly(1-hexadecene), and poly(1-octadecene). The flow behavior was investigated by use of a Weissenberg rheogoniometer. Measurements on poly(1-butene) were also made using an Instron capillary rheometer. The empirical relationship developed by Cox and Merz was obeyed for the entire series of poly( 1-olefins) a t all temperatures investigated. Graessley's theory was used to calculate the flow curves for the poly(1-olefins) from the measured molecular weight distributions. The purpose was to investigate the effect of polymer composition on the shear rate dependence of viscosity. It was found that all experimental flow curves except those for poly(1hexene) can be fitted with the calculated curves from the individual molecular weight distributions. The conclusion is made that flow curves of poly(1-olefins) depend predominately on molecular weight distribution and are essentially independent of side-chain length even for poly(1-olefins) with pendant groups as long as 16 carbon atoms. The low-shear limiting Newtonian viscosity 70 for all poly(1olefins) was expressed by, 70 = KMw3 or by qo = K'pw3 4, where aw is the weight-average molecular weight and pu is the weight-average degree of polymerization. The K and K' values obtained decrease systematically as the side chain is increased.