Dafeng Zheng

Preparation, characterization, and properties of novel bisphenol-A type novolac epoxy-polyurethane polymer with high thermal stability

In this study a series of modified bisphenol-A type novolac epoxy resins (MNEPs) were synthesized from bisphenol-A type novolac epoxy resin (NEP) and propionic acid (PA) by a one-step ring-opening reaction process in the presence of tetramethylammonium bromide as catalyst. Fourier transform infrared and 1 H-NMR were employed to confirm the chemical structures of the MNEPs. The spectra results indicated that MNEPs with different hydroxyl contents were obtained successfully by different ring-opening rates of NEP. In addition, Intercross-linked epoxy-polyurethane composites (MNEP-PUs) were also obtained by curing reaction among MNEP, cross linker polyisocyanate IL1351 and phthalic anhydride(PHA). The thermal stability of MNEP-PUs and the conventional polyol PU A450/IL1351 were determined and compared. The thermal analysis demonstrated that the obtained MNEP-PUs exhibited much better thermal stability than the conventional polyurethane system A450/IL1351, and the thermal stability of MNEP-PUs was correlated to the content of MNEP. Moreover, physico-chemical properties of MNEP-PUs such as pencil hardness, adhesive attraction, solvent resistance were reported. It demonstrated that incorporating MNEP into MNEP-PUs as inherent hardness of MNEP-PUs could greatly improve pencil hardness, adhesive attraction, water, acid and alkali resistance of MNEP-PUs.

Preparation and characterisation of aluminium pigments encapsulated by composite layer containing organic silane acrylate resin and SiO2

Purpose – The purpose of this paper is to enhance the anticorrosion property of aluminium pigments and to improve their compatibility with polymers in coating.Design/methodology/approach – Aluminium pigments encapsulated by organic‐inorganic layer were prepared by hydrolysis and condensation of organic silane acrylate resin and tetraethoxy silane (TEOS) on the surface of pigments via sol‐gel method. TEOS and poly (methyl methacryalte‐n‐butyl acrylate‐vinyl triethoxysilane) (PMBV) formed in advance by co‐polymerisation of methyl methacrylate (MMA), n‐butyl acrylate (BA) and vinyl triethoxysilane (VTES) were used as precursors. The adhesion property of the aluminium pigments was measured by peel test, and the loss of silvery appearance after encapsulation and acid soaking were both evaluated by colour lightness difference (ΔL) measurement. The encapsulated aluminium pigments were further characterised by means of FTIR, SEM, TG and XPS.Findings – It was found that PMBV‐SiO2 thin films could be formed on the ...

Studies on Cure Kinetics of Poly(phenylene ether)/Epoxy Resin System Using an Advanced Iso-Conversional Method

The kinetics and mechanism of poly(phenylene ether)/epoxy resin (PPE/EP) cure system were investigated using an advanced iso-convensional method (AICM). The curing experiments of a PPE/EP cure system with different PPE/EP ratios were carried out by means of non-isothermal differential scanning calorimetry (DSC) with different heating rates of 5, 10, 15 and 20°C/min. From the DSC curves, it was shown that the curing mechanism of PPE/EP is very complicated, and PPE content affects most cure kinetic parameters. A variation of the effective activation energy with the extent of conversion was obtained by AICM and analyzed.

Thermal stability, curing kinetics and properties of polyurethanes system for in‐mould decoration ink

Purpose – The purpose of this paper is to study thermal stability, curing kinetics and physico‐chemical properties of polyurethanes systems for application in in‐mould decoration (IMD) ink.Design/methodology/approach – The thermal stability of three Polyurethane (Pu) systems A, B, C were evaluated by thermogravimetric analysis (TGA). The kinetic parameters of the curing reaction of Pu system C were calculated using non‐isothermal curing kinetics analysis, including the activation energy Ea, the reaction rate constant K(T), the reaction order n, the initial curing temperature (Ti), the peak temperature (Tp), and the finishing temperature (Tf). Additionally, physico‐chemical properties were also evaluated such as flexibility, impact resistance, pencil hardness, adhesive attraction and solvent resistance.Findings – TGA showed that thermal decomposition temperature T5 (5 wt.% weight loss), T10 (10 wt.% weight loss) and Tend (decomposition termination temperature) of Pu system C was 344°C, 363°C, and 489°C, re...

Organic modification of cerium–zirconium mixed oxide mesoporous materials

Abstract Cerium–zirconium mixed oxide mesoporous materials were synthesised by using block polymer Pluronic P123 as soft template under the hydrothermal conditions. To enhance the interfacial interaction of cerium–zirconium mixed oxide mesoporous materials in filled polymer composites, an organic grafting method was applied to modify mesoporous materials by treating with oleic acid or silane coupling agent and grafting polymethylmethacrylate (PMMA) onto the mesoporous particles. The structural and surface properties of CeO2–ZrO2 mesoporous particles before and after organic modification were characterised by different methods. The results showed that the desired polymer chains were covalently bonded to the surface of CeO2–ZrO2 mesoporous particles to increase lipophilic degree and reduce the aggregation of these particles. It was also found that the heat decomposition temperature of PMMA grafted CeO2–ZrO2 was higher than that of pure PMMA, which demonstrated that the CeO2–ZrO2 mesoporous materials were potential superior performance filler into thermoplastic polymers to improve polymer properties.