Electron beam (E-beam) radiation initiated reactions in styrenic block copolymers (SBCs), including poly (styrene-block-butadiene-block-styrene) (SBS), poly (styrene-block-isoprene-block-styrene) (SIS) and a newly developed poly (styrene-block-isoprene/butadiene-block-styrene) (SIBS) were investigated. The gel content of SBCs after E-beam exposure was calculated and the molecular weight characteristic of soluble portion was analyzed by size exclusion chromatography (SEC). The results showed that gel content increased with increasing of E-beam radiation dose and the low molecular weight material was generated after E-beam exposure. This indicated that both crosslinking and chain scission reactions took place during the E-beam exposure. The crosslinking reaction was the predominating reaction. The structures of gel portion of SBCs were analyzed by solid state nuclear magnetic resonance (NMR). Equilibrium swelling showed that a tighter network was formed at higher radiation dose. Cylindrical morphologies were observed by both small-angle X-ray scattering (SAXS) and atomic force microscopy (AFM). The effect of E-beam on morphologies of ozone etched SBCs was also investigated. It was found that the films of SBCs after E-beam crosslinking were able to maintain a relatively intact morphology after ozonolysis, while SBCs without E-beam crosslinking lost the cylindrical morphology after ozonolysis. (C) 2016 Elsevier B.V. All rights reserved.

Three maleimide-terminated imide (MTI) oligomers/polymers with varying molecular weight were synthesized and characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR) spectroscopy, mass spectroscopy, and size exclusion chromatography (SEC). The MTI oligomers were formulated with two reactive diluents, N,N-dimethylacrylamide (DMAA) or N-vinylpyrrolidone (NVP), and were photopolymerized with and without a photoinitiator. The kinetics of film formation was investigated using real-time FTIR and photo-differential scanning calorimetry (DSC). Thermal and viscoelastic properties of UV cured films were studied by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and differential scanning calorimetry (DSC). The reaction rate and conversion were improved by adding a photoinitiator. MTI oligomer with low molecular weight ((M) over bar (n) similar to 2 kg/mol) MTI-2k had the highest reaction rate and final conversion. More than 90% of conversion was achieved after exposure to UV light for 60 s. A wide alpha-transition (tan delta) for all UV cured films was observed, indicating a heterogeneous system. When no photoinitiator was used, the MTI/NVP formulations polymerized, while the MTI/DMAA formulations did not. It was proposed that the NVP could react with MTI oligomers via a donor/acceptor complex, and the DMAA could not due to the electron-poor double bond. (C) 2016 Published by Elsevier B.V.

The effect of multifunctional monomers or oligomers (MFM/O) additives on electron beam (E-beam) radiation induced crosslinking of poly (styrene-block-isoprene/butadiene-block-styrene) (SIBS) was studied. Ten types of MFM/O were investigated, including trimethylolpropane trimethacrylate (TMPTMA), trimethylolpropane triacrylate (TMPTA), triallyl cyanurate (TAC), polybutadiene diacrylate (PB-diacrylate), ethylene glycol dimethylacrylate (EGDMA), butylene glycol dimethacrylate (BGDMA), 1,2-polybutadiene. The effects of MFM/O concentration and E-beam radiation dose on properties of SIBS were studied including tensile strength, elongation-at-break, modulus, gel content, equilibrium swelling and crosslink density. TMPTA significantly improved the tensile modulus and crosslink density of SIBS. SIBS with TMPTMA and TMTPMA with inhibitor showed a 50% increase in tensile strength. The solubility of MFM/O in SIBS was also investigated by a selective swelling method. The MFM/O were found to be soluble in both phases of SIBS. The viscosity of SIBS with methacrylate type MFM/O was stable at 200°C.

The effect of electron beam (E‐beam) radiation on a series of styrenic block copolymers (SBCs) was investigated. These SBCs included newly developed poly(styrene‐block‐isoprene/butadiene‐block‐styrene) (SIBS), poly(styrene‐block‐butadiene‐block‐styrene) (SBS), and poly(styrene‐block‐isoprene‐block‐styrene) (SIS). The tensile properties, stress relaxation, molecular weight, and dynamical mechanical properties were studied. Generally, the crosslink density and tensile moduli of SBCs increased with increasing of E‐beam radiation dose. The tensile strength of SIBS and SIS was shown to first decrease at lower E‐beam radiation dose (<120 kGy) and then increase at higher radiation dose (>190 kGy). The tensile strength of SBS was significantly decreased at high E‐beam radiation dose (>190 kGy). This was attributed to the differences between entanglement before E‐beam radiation and the homogeneity of the crosslink network after exposure. POLYM. ENG. SCI., 54:2979–2988, 2014. © 2014 Society of Plastics Engineers

This article is an overview of the chemistry and driers used in autoxidatively cured coatings and in particular alkyds. The drying process for alkyds and other unsaturated fatty acid materials is based on a series of chemical reactions known as autoxidation. The autoxidative process is usually catalyzed by metal salts known as driers. Numerous of investigations have elucidated the catalytic activity and reaction mechanism of the drying process. Spectroscopic techniques, especially mass spectrometry, have been used to study the autoxidation process and its products. Recent investigations on the oxidative drying of alkyd coating films are presented with a focus on both metal based and more environmental friendly means of catalysis.

Phthalic acid and its photochemical degradation has been determined in snow and rainwater samples collected during winters (2003–2010) in the Southeast of Massachusetts using capillary gas chromatography (GC) with flame ionization and mass spectrometric detection. Water samples were dried using a rotary evaporator and derivatized with a 14% BF3/methanol reagent before GC analysis. The developed method proved simple and accurate. Phthalic acid was found in snow samples collected in a concentration range of 7.22–76.5nM. The photodegradation of phthalate was carried out under 300nm UV light. The direct photodecomposition of the acid is slow (5%h−1). However, the addition of dissolved Fe(III) species at 2.0μM accelerated the light-induced degradation of phthalic acid by 3.5times in the atmospheric water samples. Photodegradation rates of phthalic acid increases with decreasing pH value of water samples in the range of pH 2.8–4.5.