A dramatic improvement of the toughness of polydicyclopentadiene (PDCPD) composite containing low amounts of vinyl-functionalized SiO2 was achieved, and the toughening mechanism was investigated. Considering the nonpolarity of the DCPD monomer and the probability of covalent bonding between SiO2 and DCPD, vinyl-functionalized SiO2 (V-SiO2) with a high content of vinyl groups was prepared by a facile, reproducible, one-step, remodeled synthetic sol–gel process. The V-SiO2 was characterized with respect to the content of vinyl groups, particle size, and morphology by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), dynamic light scattering (DLS), and field-emission scanning electron microscopy (FE-SEM). PDCPD/V-SiO2 composites were prepared by in situ polymerization. The mechanical properties of the PDCPD/V-SiO2 composites were investigated by universal testing machine (UTM) and dynamic mechanical analysis (DMA). A slight decrease in the yield strength was observed with increasing loading of V-SiO2, whereas the elongation at break increased substantially from 9.0% to 143.4% and the tensile toughness increased by a factor of 14 compared to that of neat PDCPD when just 0.2 wt % V-SiO2 had been added. The dramatic toughness enhancement is attributed to the formation of microvoids and microcracks during the process of stretching, which can absorb a great deal of energy.

Precisely substituted polyethylenes have well-defined primary structures and aggregation architecture. Herein, precisely bromine-substituted polyethylene (PE21Br) was chosen as an ideal model to investigate the substituent impact on epitaxial crystallization upon one-dimensional carbon nanotubes (CNT) and two-dimensional reduced graphene oxide (RGO) via solution crystallization. The abilities of different dimensional nanofillers to induce ordered chain packing structures were compared. Transmission electron microscopy (TEM) images showed that kebab-like and rod-like nanofiller-induced crystals were separately observed on the surfaces of CNT and graphene, and selected area electron diffraction (SAED) pattern revealed that the c-axis of the polymer chain was parallel to the surface of RGO. Fast-scan differential scanning calorimetry (Flash DSC) revealed that the melting points of the crystals grown on CNT and graphene were increased by 19 and 99 °C, respectively. More importantly, X-ray diffraction (XRD) suggested that CNT and RGO induced the transition of the crystal structure of PE21Br from the triclinic to orthorhombic form, but with different orderness. More ordered lattice structures and higher melting temperatures of PE21Br/RGO nanocomposites are ascribed to the perfect lattice matching between PE21Br and RGO. This study not only provides a method for fabricating bromine-functionalized polyolefin nanocomposites, but is also anticipated to open up a new opportunity for improving the service temperature of substituted polyethylene by means of epitaxial crystallization.

The ultrahigh molecular weight polyethylene (UHMWPE) fibers were obtained directly from the industrial production line. Two-step industrial hot-drawing-to-specific-drawing ratios were carried out at the temperature of 120 and 130 °C, respectively. Small-angle X-ray scattering (SAXS) measurements using synchrotron radiation were applied to study the evolution of kebab structure and the formation of shish structure. The slight increase of long period and the rapid decrease of lateral sizes indicated the destruction of original lamellae which was accomplished by chain slip resulted in the orientation of lamellae to form shish structure. The decrease of average shish length was explained that the formed new shish structure had shorter shish length than the original shish at the early stage with the high concentration of spinning solution. Wide-angle X-ray diffraction (WAXD) measurements were performed to explore the changes of the degree of orientation of the crystals. It was found that the elevated drawing temperature was benefited to the evolution of the orientational order. The DSC result confirmed the evolution of shish–kebab structure through the melting behavior.

The development of a highly efficient and pH-tolerant Fenton system has been one of the most important and challenging goals in water remediation. Herein, a green natural organic ligand, L-cysteine (Cys), was innovatively introduced into Fenton's reagent to construct an excellent catalytic oxidation system. The introduction of Cys into the Fenton system expanded the effective pH range up to 6.5 and achieved a superior oxidation efficiency, representing about 70% higher removal ratio and 12 times higher reaction rate constant with methylene blue dye as the probe compound. The Cys-driven Fenton reaction presented an outstanding pH adaptability and oxidative activity compared with other common organic ligands or reducing agent-modified Fenton reactions. An investigation of the reaction mechanism indicated that the addition of Cys into the system accelerated the Fe(III)/Fe(II) cycle, and led to a relatively steady Fe(II) recovery, which enhances the generation of hydroxyl radicals (˙OH). The presence of Cys in the Fenton system remarkably reduced the apparent activation energy from 95.90 to 47.93 kJ mol−1. The findings from this study provide a feasible approach for a highly efficient and pH-tolerant wastewater treatment process with environmentally benign characteristics, and initiates an inspiring research domain of amino acids in the environmental catalysis field.

The open-cell structure foams of linear low-density polyethylene (LLDPE) and linear low-density polyethylene (LLDPE)/multi-wall carbon nanotubes (MWCNTs) composites are prepared by using supercritical carbon dioxide (sc-CO2) as a foaming agent. The effects of processing parameters (foaming temperature, saturation pressure, and depressurization rate) and the addition of MWCNTs on the evolution of cell opening are studied systematically. For LLDPE foaming, the foaming temperature and saturation pressure are two key factors for preparing open-cell foams. An increase in temperature and pressure promotes both the cell wall thinning and cell rupture, because a high temperature results in a decrease in the viscosity of the polymer, and a high pressure leads to a larger amount of cell nucleation. Moreover, for the given temperature and pressure, the high pressurization rate results in a high pressure gradient, favoring cell rupture. For LLDPE/MWCNTs foaming, the addition of MWCNTs not only promotes the cell heterogeneous nucleation, but also prevents the cell collapse during cell opening, which is critical to achieve the open-cell structures with small cell size and high cell density.