Pattern preparation

C-PE and L-PE have been ready utilizing beforehand reported procedures [14]. Cyclic and linear polyoctenamers, that are PE precursors, have been synthesized by the ring-opening metathesis polymerization of cis-cyclooctene after catalysis by a cyclic Ru-alkylidene advanced and a second-generation Grubbs catalyst, respectively. Each PE precursors have been hydrogenated with p-toluenesulfonyl hydrazide and transformed to the corresponding PE. The chemical buildings of the samples have been confirmed via FT-IR spectroscopy (JASCO FT/IR-410 spectrometer) and ¹H- and ¹³C-NMR spectroscopy (JEOL AL300 SC-NMR). The load common molecular weights, M_w, of C-PE and L-PE have been decided by measuring the intrinsic viscosities [η] of the PE precursors in tetrahydrofuran at 30 °C [14]. The M_w values of the C-PE and L-PE precursors have been transformed to these of C-PE and L-PE, respectively, by assuming 100% hydrogenation. The M_w values of C-PE and L-PE have been 175 × 10³ and 154 × 10³ g/mol, respectively. The equilibrium melting temperatures (T_m⁰) of C-PE and L-PE [15, 16] have been calculated by assuming that the T_m⁰ of C-PE was equal to that of the proper prolonged chain crystals of an L-PE specimen with half the M_w of the C-PE specimen. The T_m⁰ values of C-PE and L-PE have been 140.9 and 146.1 °C, respectively. For the T_m⁰ of blended samples (T_m⁰(C/L)), we assumed an additive property given by the next equation:

the place T_m⁰(C-PE) and T_m⁰(L-PE) are the T_m⁰ values of the C-PE and L-PE homopolymers, respectively. Because the mix of C-PE and L-PE could possibly be thought to be a wonderfully miscible system, this therapy was accepted as a first-order approximation.

A mix of C-PE and L-PE was ready as follows: C-PE and L-PE homopolymers have been blended with sizzling o-xylene. The answer was poured into extra methanol, and the precipitate was recovered. The powder blended samples have been dried in vacuo. The load fraction of L-PE (Φ_L-PE) within the blended samples was assorted from 0 to 100 wt%.

Devices and measurements

The isothermal crystallization habits within the quiescent state was noticed via polarizing optical microscopy (POM; Olympus, BX-53) utilizing a sizzling stage (Linkam 10002L) and differential scanning calorimetry (DSC; PerkinElmer, DSC 8000) in a nitrogen stream (20 mL/min) to keep away from pattern degradation. The samples have been sandwiched between two cowl glasses for POM evaluation and positioned in an Al pan for DSC evaluation. Every pattern was heated at a charge of 30 °C/min and annealed at a temperature above T_m⁰ (soften annealing temperature T_max = 160 °C) for 1 min to erase the earlier thermal historical past. The samples have been then cooled to T_c at a charge of 30 °C/min. The vary of ΔT was 25.5–28.5 Okay. The isothermal crystallization habits was recorded via POM utilizing a video digicam (Victor KY-F1030). Throughout isothermal crystallization, we measured the warmth movement as a operate of crystallization time t utilizing DSC. The experimental situations of isothermal crystallization are summarized in Desk 1.

Kinetic evaluation with the Avrami equation

On this research, the isothermal crystallization kinetics of the C-PE and L-PE blends have been analyzed utilizing the classical Avrami equation [17, 18]. The Avrami equation could possibly be expressed as follows:

the place Χ_t is the relative diploma of crystallinity at time t, ok is the general crystallization charge fixed, and n is the Avrami index. Χ_t could possibly be outlined as follows:

the place ΔH_t is the warmth generated at t and ΔH_∞ is the whole warmth generated till the tip of crystallization. Equation (2) could possibly be reworked right into a double logarithmic kind as follows:

The Avrami index n could possibly be decided from the slope of the ({{log }}left[-{{{{mathrm{ln}}}}}left(1-{{{{{{rm{{X}}}}}}}}_{t}right)right]) vs. log t curve. Becoming between experimental information and Eq. (4) was carried out with the information below the situation of X_t < 0.2, as really useful by Lorenzo et al. [18]. The becoming parameters are summarized in Supplementary Desk S1. The Avrami index n is expounded to the nucleation and geometry forms of the rising crystal, and its worth often ranges from 0.5 to 4 [17]. By substituting Χ_t = 0.5 into Eq. (4), we may acquire t_1/2; that’s, we may acquire the time obligatory for the completion of fifty% crystallization as follows:

On this research, we calculated the t_1/2 values utilizing the n and ok values decided from the Avrami plot primarily based on Eq. (4). Notably, the half-crystallization time included the contributions of each major nucleation and crystal progress. On this research, we didn’t intend to show the validity of the Avrami evaluation, and we solely used it for the quantitative estimation of t_1/2. For reference, the t_1/2 values obtained from the curve of the relative diploma of crystallinity (t_{1/2 exp}) and calculated by Eq. (5) utilizing ok and n values decided from the Avrami plot (t_{1/2 match}) are summarized in Supplementary Desk S2.