This is an editorial article. It has no abstract.
Core-shell silicone acrylic emulsions with 3-methacryloxypropyl trimethoxysilane (MPTS) in the shell were prepared by seeded polymerization with the assistance of polymerisable maleate surfactant (MT). Fourier transform infrared (FT-IR) demonstrated the incorporation of polymerisable surfactant in copolymer. It was found that small amount of octadecyl acrylate was beneficial to emulsion stability with decreasing the particle size from 194.6 to 165.7 nm. It was also found that the particle size increased from 165.7 to 242.9 nm with the increase of MPTS concentration. Furthermore, rheological measurement indicated that the emulsion was endowed with pseudoplasticity. At low shear rate, marginal reduction in viscosity was detected when MPTS concentration increased to 2%, while great increase in viscosity was observed with higher MPTS concentration, the interaction force among emulsion particles became the predominant factor instead of particle size. In addition, better water resistance was observed when MT concentration was lower than 1.5%, and MPTS concentration higher than 2%. Moreover, surface roughness was increased with MPTS addition, the crosslinking among core and shell reconstructed the surface morphology of film.
To control the swelling of sodium carboxymethylcellulose (CMCNa) membranes, mixtures of CMCNa and glutaraldehyde (GA) and mixtures of CMCNa as an organic component and tetraethoxysilane (TEOS) as an inorganic component were prepared, and CMCNa/GA cross-linked membranes and CMCNa/TEOS hybrid membranes were formed. In the separation of an ethanol/water azeotrope by pervaporation (PV), the effects of the GA or TEOS content on the water/ethanol selectivity and permeability of these CMCNa/GA cross-linked and CMCNa/TEOS hybrid membranes were investigated. Cross-linked and hybrid membranes containing up to 10 wt% GA or 10 wt% TEOS exhibited higher water/ethanol selectivity than CMCNa membrane without any cross-linker. This resulted from both increased density and depressed swelling of the membranes by the formation of a cross-linked structure. The relationship between the structure of the CMCNa/GA cross-linked membranes and CMCNa/TEOS hybrid membranes and their permeation and separation characteristics for an ethanol/water azeotrope during PV is discussed in detail.
A novel functional ionic liquid (IL), 1-methylimidazolium methacrylate (MimMa), was synthesized for modifying styrene butadiene rubber (SBR)/silica composites. MimMa was found to be readily polymerized via the initiated radical mechanism and could be analogously grafted onto rubber chains during vulcanization. Substantial hydrogen bonding between polymerized MimMa (poly(MimMa)) and silica can facilitate the silica dispersion and improve the SBR/silica interfacial bonding. Filler networking, curing behavior, silica dispersion and mechanical performance of the modified SBR/silica composites were studied. With a low concentration of MimMa, remarkable improvements in the interfacial interactions and mechanical properties were achieved which was attributed to the improved silica dispersion and strengthened interfacial bonding induced by MimMa. A modified interphase structure was accordingly proposed and related to the mechanical performance of the modified SBR/silica composites.
In this study, the modified ultraviolet (UV) curable waterborne polyurethane was obtained from isophorone diisocyanate (IPDI), polyethylene glycol (PEG, MW=600), α,α-dimethylol propionic acid (DMPA), hydroxyethyl acrylate (HEA) and bisphenol A. The rigid moiety was introduced into the main chain of polyurethane to improve its heat-resistance. The copolymer structure was confirmed by Fourier transform infrared spectroscopy (FT-IR). Thermal property and UV curable behavior of the coatings were investigated. The glass transition temperature (Tg) of the modified film was determined by differential scanning calorimetry (DSC). Thermal gravimetric analysis (TGA) was employed to investigate the thermal stability of the modified film. The results show that the average particle diameters increased from 69.25 to 95.12 µm as the content of bisphenol A increased from 0.00 to 9.25%. The optimum bisphenol A dosage was 7.23% (wt%), the Tg of the modified film increased by 7.07°C and 5% weight-loss temperature (233°C) increased by 14°C. The optimum irradiation time was 10–20 minutes after the coatings being painted on an armor plate at room temperature and initiator dosage was 5% (wt%) of the latex.
A series of homo- and copolyimides based on mixed thioetherdiphthalic anhydride isomers (mixed-TDPA) were synthesized with several kinds of aromatic diamines. The properties of these polyimides were characterized by glass transition temperature (Tg), thermal decomposition temperature, and melt processability. A series of copolyimides were prepared to achieve high Tg concurrently with melt processability by means of selecting appropriate diamines and their composition in the copolyimides. As a result, we obtained rheological information for a series of polyimide resins as a function of temperature, time and shear rate. It is found that the processability (e.g., melt viscosity of polyimides) and ultimate product properties (e.g., Tg of polyimides) can be systematically varied by changing the variety and composition of the aromatic diamines. It has been demonstrated that the incorporation of meta- or flexible diamines improve the melt processability of polyimides significantly. Meanwhile, Tg of copolyimides from dual-diamines can be predicted and regulated. Accordingly, copolyimides from 1,3-phenylenediamine (m-PDA) and 3,4’-oxydianiline (3,4’-ODA) were obtained with higher Tg and lower melt viscosity. Such correlations of chemical structures and rheological behavior provide the necessary database for tailor-making new polyimide systems with desirable processability and physical properties.
A novel approach was developed for the surface modification of the multi-walled carbon nanotubes (MWCNTs) with high percentage of grafting (PG%) by the grafting of polymer via the Friedel-Crafts alkylation. The graft reaction conditions, such as the amount of catalyst added, the reaction temperature, and the reaction time were optimized for the Friedel-Crafts alkylation of the MWCNTs with poly(vinyl chloride) (PVC) with anhydrous aluminum chloride (AlCl3) as catalyst in chloroform (CHCl3). The Fourier Transform Infrared (FT-IR), Raman, and thermogravimetric (TGA) analysis showed that PVC had been successfully grafted onto MWCNTs both at the ends and on the sidewalls by the proposed Friedel-Crafts alkylation. The PVC grafted MWCNTs (PVC-MWCNTs) could be dispersed well in organic solvent and the dispersion was more stable.
In this study, polypropylene (PP)/linear low-density polyethylene (LLDPE) and maleic anhydride grafted polypropylene (MAPP)/LLDPE blend systems were comparatively investigated. The blends and composites contained equal amounts of the two polymers, and the compatibility and miscibility between the two polymers were investigated. Composites with 10, 20 and 30 wt% wood powder (WP), but still with equal amounts of the two polymers, were prepared and investigated. The morphologies, as well as mechanical and thermal properties, of the blends and the blend composites were investigated. The MAPP/LLDPE blend and composites showed better properties than the PP/LLDPE blend and composites as a result of the stronger interfacial interaction between MAPP, LLDPE and WP. The SEM and DSC results of the PP/LLDPE/WP blend composites showed that WP located itself more in the LLDPE phase. In the MAPP/LLDPE/WP composites the WP was in contact with both polymers, although it had a greater affinity for MAPP. The TGA results show that the MAPP/LLDPE blend and composites are more thermally stable than the PP/LLDPE blend and composites.