Fractionated Crystallization Behavior of Low-Molecular-Weight Polyethylene Grafted onto SiO₂Nanoparticles

Abstract

The synthesis of polymer-grafted nanoparticles is crucial for the development of polymer nanocomposites with excellent properties, but the synthesis of polyethylene (PE)-grafted SiO2 nanoparticles (PE-g-SiO2 NPs) remains a significant challenge due to the chemical inertia of PE. In this study, PE-g-SiO2 NPs with different grafting densities and molecular weights were successfully synthesized by a simple “grafting to” method, and differential scanning calorimetry was used to study the crystallization behavior of grafted PE. Some PE-g-SiO2 samples exhibited three crystallization peaks in the cooling curve (i.e., fractionated crystallization phenomena). Self-nucleation (SN) and successive SN and annealing (SSA) results reveal that the nanoparticles in PE-g-SiO2 samples provoke both confinement and nucleation effects on the grafted PE chains. For PE-g-SiO2 NPs with higher grafting density and molecular weight, the PE chains are more stretched and the interfacial chain segmental dynamics are less suppressed, which enhance the nucleation effect and weaken the confinement effect.

Effect of the Miscibility between Grafted and Matrix Chains on the Dispersion and Crystallization of Polyethylene-Grafted Silica Nanocomposites

“…HDPE1289- g -SiO 2 nanoparticles were prepared by the “grafting to” method according to our earlier study . First, the SiO 2 nanoparticles were modified by APTMS, and the vinyl-terminated polyethylene (HDPE1289) was modified by m-CPBA to introduce reactive amino and epoxy groups; then, PE was chemically grafted to the SiO 2 surface via the reaction of amino and epoxy groups.…”

“…HDPE1289-g-SiO 2 nanoparticles were prepared by the "grafting to" method according to our earlier study. 30 First, the SiO 2 nanoparticles were modified by APTMS, and the vinylterminated polyethylene (HDPE1289) was modified by m-CPBA to introduce reactive amino and epoxy groups; then, PE was chemically grafted to the SiO 2 surface via the reaction of amino and epoxy Typically, 95 mg of neat PE and 0.5 wt % 215B antioxidant were added into 10 mL of xylene and stirred at 100 °C to dissolve. Meanwhile, 5 mg SiO 2 nanoparticles was added into 5 mL of xylene and then ultrasonicated for 10 min to promote dispersion.…”

“…However, the preparation of PE-grafted nanoparticles is difficult because of the lack of active chemical groups in PE chains. Currently, there are only a few works on preparing PE-grafted nanoparticles by the “grafting to” − or “grafting from” − methods. In most cases, the PE-grafted nanoparticles can be well dispersed in PE matrices.…”

Direct relationship between crystalline structure and part deformation of polypropylene copolymer parts fabricated by material extrusion additive manufacturing

“… is the weight fraction of PP or PE block in copolymer. for PE and PP are 293 44 and 165 J/g, 45 respectively.…”

Significantly Tunable Foaming Behavior of Blowing Agent for the Polyethylene Foam Resin with a Unique Designed Blowing Agent System

“…Polyethylene (PE) is a commonly used plastic material with a wide range of applications. − The research studies of PE have also received extensive attention for its synthesis, modification, − application, − degradation, , etc. Foaming technology has been widely applied in PE products, such as injection foaming and rotational foaming. − The foaming behavior directly affects the performance of the PE foaming products.…”