Mesophase Formation in Random Propylene-co-1-octene Copolymers

Abstract

The development of the mesophase has been studied by either fast scanning calorimetry or conventional DSC in a series of random propylene-co-1octene copolymers. The results show that the mesophase formation rate can be easily tailored in a very wide range of magnitudes, covering almost 4 orders. That decrease is similar to that found previously in propylene-co-1-pentene copolymers at the same wt % of counits. On the contrary, the pertinent unit for the melting point depression (and for the crystallization temperatures) is found to be the mol % comonomer content. Consequently, the "kinetic" parameters in the ordering of iPP copolymers can be tailored somewhat independently of the transition temperatures just by changing the size of the comonomeric units. Additional X-ray diffraction experiments, employing either conventional or synchrotron radiation, were also carried out on these 1-octene copolymers in order to determine the precise nature of the different transitions.

Fourier Transform Infrared Spectroscopy study of polymorphism in propylene-co-1-pentene copolymers: Trigonal form identification

“…The corresponding overall degree of crystallinity f total c at room temperature was calculated knowing the totally amorphous profiles, following the procedure reported before [43]. Moreover, the proportion of the different ordered phases: mesomorphic, a, k, or d modification has been also estimated considering the relative areas of their characteristic diffraction peaks [43].…”

“…Moreover, the proportion of the different ordered phases: mesomorphic, a, k, or d modification has been also estimated considering the relative areas of their characteristic diffraction peaks [43]. The results obtained are reported in Table 2.…”

Synthesis, molecular characterization, evaluation of polymorphic behavior and indentation response in isotactic poly(propylene-co-1-heptene) copolymers

“…Consequently, there exists a reduction in the rate of mesophase formation that depends upon comonomer content at a given counit and upon length of the chain branches at a specific content. Mesomorphic entities formation is, then, easier as the comonomer content increases and as the length within branches is enlarged [16,30,31].…”

Influence of structure on the properties of polypropylene copolymers and terpolymers

“…These features make terpolymers excellent products for film packaging applications. In addition to presenting very good optical properties, they have a crystalline structure full of imperfections that leads to wide melting curves, an important advantage in the sealing of the film that can be 14 done at lower temperature, thus increasing the speed of the production process. …”

“…[5][6][7][8][9][10] Moreover, a kind of mesomorphic form has been found to appear not only in homopolymer but also in different random copolymers, with comonomers such as ethylene, 1-butene, 1-pentene and other -olefin copolymers. [11][12][13][14] Among the different paths for modifying the ability to crystallize the iPP and the type of polymorph desired, this paper focuses on the introduction of comonomer units.…”