Shuiping Li

Investigations on mechanical characteristics of glass fiber reinforced epoxy composite modified with amino-terminated hyperbranched polymer

Glass fiber, GF, which was first hydroxylated and silanized, was incorporated into epoxy resin modified with amino-terminated hyperbranched polymer (ATHBP) to obtain high performance composite. The effects of GFs content on the mechanical properties of composites were investigated, discussing the results from flexural, tensile, and impact tests. The composites revealed noticeable improvement in flexural strength, tensile strength as well as impact strength but slow decrease in elongation at break, compared to the epoxy/ATHBP thermoset. FESEM morphology results indicated the good compatibility between epoxy matrix and GF in the appearance of ATHBP and showed that the toughening mechanism was mainly attributed to the stress transfer mechanism.

Preparation of TiO2/Al-MCM-41 mesoporous materials from coal-series kaolin and photodegradation of methyl orange

TiO2/Al-MCM-41 mesoporous materials were prepared via sol-gel method by loading titania onto Al-MCM-41 mesoporous molecular sieve by hydrothermal treatment from coal-series kaolin as raw material. The TiO2/Al-MCM-41 mesoporous materials were characterized by XRD, FT-IR, HRTEM, N2 adsorption-desorption and the photocatalytic degradation of methyl orange solution under visible light irradiation. The results showed that the TiO2/Al-MCM-41 mesoporous materials possessed a high surface area of 369.9–751.3 m2/g and a homogeneous pore diameters of 2.3–2.8 nm. The titania crystalline phase was anatase, and the particles size of TiO2 increased with TiO2 content. The Al-MCM-41 mesoporous materials exhibited excellent photodegradation activity under visible-light irradiation for methyl orange.

Impact Resistance Enhancement by Adding Core-Shell Particle to Epoxy Resin Modified with Hyperbranched Polymer

A core-shell particle was fabricated by grafting amino-terminated hyperbranched polymer to the surface of silica nanoparticles. The influences of core-shell particle contents on the tensile and impact strength of the epoxy thermosets modified with amino-terminated hyperbranched polymer were discussed in detail. For comparison, core-shell particle was added into the epoxy/polyamide system for toughness improvement. Results from tensile and impact tests are provided. The introduction of core-shell particle into the epoxy/polyamide systems just slightly enhanced the tensile and impact strength. The incorporation of 3 wt % core-shell particle could substantially improve the tensile and impact strength of epoxy/amino-terminated hyperbranched polymer thermosets. Field emission-scanning electron microscope images of the impact fracture surfaces showed that the excellent impact resistance of epoxy/amino-terminated hyperbranched polymer/core-shell particle thermosets may be attributed to the synergistic effect of shearing deformation and crack pinning/propagation, which is induced by the good compatibility between epoxy matrix and core-shell particle in the presence of amino-terminated hyperbranched polymer.

Evaluation of glass-fiber grafted by epoxide-terminated hyperbranched polymer on the effect of mechanical characterization of epoxy composites

Abstract In this study, glass-fiber, grafted by epoxide-terminated hyperbranched polymer (GF-HBPE), was incorporated into epoxy resins for reinforcement purpose. The effects of GF-HBPE content on mechanical properties of the resulting epoxy-based composites, such as tensile strength, percentage elongation at break, flexural strength, and impact strength, were investigated. The experimental results revealed that GF-HBPE substantially outperformed impact resistance in both tensile and flexural tests. For instance, the tensile strength, percentage elongation at break, flexural strength, and impact strength of the epoxy composite with 1 wt% GF-HBPE increase by about 23.6%, 125%, 26%, and 74.5%, respectively, compared to the unmodified epoxy thermoset.

Synthesis of LiNiO2 by two-step solid-state method

Abstract LiNiO2 was prepared through two-step solid-state reaction by mechanochemical method and heat treatment, using LiOH (Li2CO3) and Ni(OH)2 as starting materials. The influence of grinding speed and time, heat treatment time, and starting materials on the structure of LiNiO2 was studied. The as-milled samples and products were characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). The results show that uniform as-milled samples can be obtained at grinding speed of 580 rpm for 0.5 h, using LiOH and Ni(OH)2 as raw materials. Perfect crystal LiNiO2 has been prepared by calcining the as-milled samples at 700 °C for 15 h. Composite material powders consisting of Li2Ni8O10 and LiNiO2 have been obtained using Li2CO3 as lithium source.

Synthesis and characterization of hyperbranched polymer with epoxide-terminated group and application as modifier for epoxy/polyamide system

Hyperbranched polymer with epoxide-terminated group was synthesized through end-capping reaction between hyperbranched polymer with hydroxyl-terminated group and epichlorohydrin. The chemical structure of the synthesized polymer was characterized by ATR-IR and 1H NMR spectroscopy. The influence of hyperbranched polymer content on the mechanical properties and fracture toughness of epoxy/polyamide systems was investigated. The toughening mechanism was discussed basing on observing the fracture surface morphologies of epoxy/polyamide/ hyperbranched polymer system.

Synergic improvement of DGEBA/CSP/HBP composite on mechanical behavior

Hyperbranched polymer with amino end groups (HBPA) and core-shell particle (CSP, which is fabricated through grafting HBPA onto the surface of silica nanoparticle) were incorporated into an epoxy matrix to fabricate a high performance composite. The effects of CSPs contents on the mechanical properties of composites were studied, discussing the results from tensile, flexural, and impact tests. The composites revealed noticeable improvements in tensile strength, elongation, flexural strength and impact strength in comparison to the neat epoxy or epoxy/HBPA system. The glass transition temperature (Tg) was also improved by the addition of CSP. Field emission scanning electron micrograph (FESEM) indicated that HBPA could favorable improve the compatibility between CSP and epoxy matrix. And the toughening mechanisms were the synergic effect of shearing deformation, phase separation, crack propagation, crack deflection, and crack pinning.