Self-nucleation and annealing

In those cases where the injection of self-nuclei in every MD is most difficult in view of the very large number of MDs, domain III is split into two domains. Evaluation of the self-nucleation of the PE block within S35E15C50219 shows that not only domain II is absent, but upon decreasing Ts, the PE block is annealed before any detectable self-nucleation occurs (Fig. 17c). Therefore two subdomains were defined [98] domain IIIa, where annealing without previous self-nucleation occurs and domain IIIsa> where self-nucleation and annealing are simultaneously observed for Ts < 88 °C. Domain IIIsa would be the exact equivalent to the standard domain III established by Fillon et al. [75]. 

X. Sun, G. Shen, H. Shen, B. Xie, W. Yang, M. Yang, Co-crystallization of blends of high-density polyethylene with linear low-density polyethylene An investigation with successive self-nucleation and annealing (SSA) technique. J. Macromol. Sci. Part B Phys. 52, 1372-1387 (2013)... 

Orlando, FL, 7th-llth May, 2000, paper 499 CHARACTERIZATION OF POLYETHYLENE BLENDS BY USING NOVEL TECHNIQUES SUCH AS THE SUCCESSIVE SELF-NUCLEATION AND ANNEALING (SSA) AND THE FOURIER SELF-DECONVOLUTION IR SPECTROSCOPY (FSD-IR)... 

Thermal fractionation by successive self-nucleation and annealing (SSA) technique. Amongst the thermal fractionation methods, the SSA technique is the most efficient and sensitive. It is mostly employed for ethylene/a-olefin copolymers in order to evaluate in a quick way their short-chain branching (SCB) distribution. However, it can be employed to analyze the effect that any defect along the chain can produce in the distribution of linear crystallizable sequences. 

In contrast to the PE-6-PS block copolymers, when PE is covalently bonded to poly(ethylene-alt-propyl-ene) (PEP), a strong diluent effect is observed upon PE crystallization, and in the extreme case of EnEPgg, fractionated crystallization was also observed for the PE block. Additionally, the difference between being bonded to a rubbery block or bonded to a glassy block was studied by successive self-nucleation and annealing (SSA). The results showed that the dilution effect of... 

The technique of self-nucleation can be very useful to study the nucleation and crystallization of block copolymers that are able to crystallize [29,97-103]. Previous works have shown that domain II or the exclusive self-nucleation domain disappears for systems where the crystallizable block [PE, PEO or poly(e-caprolactone), PCL] was strongly confined into small isolated MDs [29,97-101]. The need for a very large number of nuclei in order to nucleate crystals in every confined MD (e.g., of the order of 1016 nuclei cm 3 in the case of confined spheres) implies that the amount of material that needs to be left unmolten is so large that domain II disappears and annealing will always occur to a fraction of the polymer when self-nucleation is finally attained at lower Ts. This is a direct result of the extremely high number density of MDs that need to be self-nucleated when the crystallizable block is confined within small isolated MDs. Although this effect has been mainly studied in ABC triblock copolymers and will be discussed in Sect. 6.3, it has also been reported in PS-fc-PEO diblock copolymers [29,99]. 

Several block copolymer systems have shown only domains I and III upon self-nucleation. This behavior is observed in confined crystallizable blocks as PEO in purified E24EP57EO1969 [29]. Crystallization takes place for the PEO block at - 27 °C after some weak nucleating effect of the interphase. Domain II is absent and self-nucleation clearly starts at Ts = 56 °C when annealed crystals are already present, i.e., in domain III (Fig. 17b). The absence of domain II is a direct consequence of the extremely high... 

Kong J, Fab X, Xie Y, Qiao W (2004) Study on molecular chain heterogeneity of linear low-density polyethylene by cross-fractionation of temperature rising elution fractionation and successive self-nucleation/annealing thermal fractionation. J Appl Polym Sci 94 1710-1718... 

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