Ultrasonication-assisted rapid determination of epoxide values in polymer mixtures containing epoxy resin

Lei

J of Applied Polymer Sci

et al. 2018

The compatibility of polymer blends is pivotal for their performance enhancement due to the large surface tension and weak interaction among individual components. In this work, epoxide hyperbranched polyurethanes (EHPU) was used to realize the compatibility between silica (SiO2), generated in situ from tetraethoxysilane, and benzoxazine (BZ). The compatibilization effect and mechanism of EHPU on SiO2/BZ were investigated via the differences of cure characteristics and kinetics between BZ, SiO2/BZ, and EHPU‐SiO2/BZ blend. EHPU‐SiO2/BZ blend exhibited lower initial curing temperature and wider curing window than those of SiO2/BZ and neat BZ. In addition, the co‐curing reaction was existed between EHPU and BZ, which contributed to the reactive compatibilization. More importantly, the growth of SiO2 particles was hindered by the nonreactive compatibilization due to the hydrogen interaction between EHPU and the silanols. Thus, the compatibilization of EHPU on SiO2/BZ blend is a result of the synergetic effect of the hydrogen interaction and the co‐curing. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46879.

Section: Methodsmentioning

confidence: 99%

Cure behavior and compatibilization of epoxide hyperbranched polyurethane on silica/benzoxazine blend

Lei

J of Applied Polymer Sci

et al. 2018

Polymers for Advanced Techs

“…Trifunctional epoxy resin from itaconic acid with a yield of 75% was obtained by removing DCM by using a rotary evaporator. The epoxide value of TEIA (1.02) was calculated by using hydrochloric acid‐acetone method . The synthesis reaction is represented in Scheme .…”

Section: Methodsmentioning

confidence: 99%

“…The epoxide value of TEIA (1.02) was calculated by using hydrochloric acid-acetone method. 38 The synthesis reaction is represented in Scheme 2. and constantly stirred to get a homogeneous mixture and degassed in vacuum oven at 65°C for 10 minutes. Then, the mixture was poured into a mold and cured at 170°C for 2 hours to obtained a completely cured resin.…”

Section: Epoxidation With M-chloroperoxybenzoic Acidmentioning

confidence: 99%

Synthesis and characterization of itaconic‐based epoxy resins

Kumar

Samal

Mohanty

et al. 2017

A trifunctional epoxy resin from itaconic acid (TEIA) was synthesized from a renewable resource-based itaconic acid by allylation of itaconic acid to form diallyl itaconate by using m-chloroperoxybenzoic acid as oxidizing agents followed by epoxidation of allylic C═C bond of diallyl itaconate methylhexahydropthalic anhydride as curing agent in the presence of 2-methyl imidazole as a catalyst. The chemical structure of the synthesized resins was confirmed by Fourier transform infrared and nuclear magnetic resonance ( 1 H-NMR and Pan et al [26] synthesized a highly functional bio-based epoxy resin from sucrose fatty acids. The higher epoxy value means that the highest number of epoxy rings, the more cross-linking occurs.Therefore, the result shows that higher mechanical properties and glass transition temperature contrast to commercialized bio-based epoxidized soybean oil (ESO). The overall properties of ESO were not similar to the conventional DGEBA, while they both are cured with methylhexahydrophthalic anhydride (MHHPA) curing agent because of the presence of long triglyceride aliphatic chain structure.Xin et al 27 synthesized cinnamic acid (Cin-epoxy)-based liquid epoxy resin with lower viscosity (0.67 Pa s) at room temperature than epoxy resin (DER 332; 3.31 Pa s), which indicates that Cin-epoxy systems have better processability and similar (T g 85°C) value of the biobased dimethylpropionic acid cured Cin-epoxy/dimethylpropionic acid networks and petroleum-based Cin-epoxy/HHPA network (T g 90°C).Samantha et al studied that the bio-based quercetin epoxy monomer that displayed comparable T g and thermal and mechanical properties than DGEBA was cured with nadic methyl anhydride curing agent.Wan et al 28 described that a eugenol-based epoxy resin (DEU-EP) with higher bio-based content of 70.2 wt% showed a higher storage,

J of Applied Polymer Sci

“…The epoxide content of HEOs was determined by hydrochloric acid‐acetone titration method proposed by He et al . A certain amount of samples (accurate to 0.0001 g) was added into a conical flask, then 10 mL hydrochloric acid‐acetone solution was added to the flask and stoppered.…”

Section: Measurements and Characterizationmentioning

confidence: 99%

“…The epoxide content of HEOs was determined by hydrochloric acid-acetone titration method proposed by He et al 15 A certain amount of samples (accurate to 0.0001 g) was added into a conical flask, then 10 mL hydrochloric acid-acetone solution was added to the flask and stoppered. The flask was then left in a ultrasonification cleaner at room temperature to dissolve the sample, two to three drops of phenolphthalein (1% ethanol solution) were added into the flask and the solution was titrated with NaOH standard solution to a pink color which did not fade within 10 s. Meanwhile, blank experiment was performed.…”

Section: Epoxide Contentmentioning

confidence: 99%

Preparation and properties of few‐layer graphene modified waterborne epoxy coatings

Yuan

Zhao

Sun

et al. 2018

Few layer graphene (FLG) has been used to improve different properties of polymers. FLG‐modified waterborne epoxy dispersions were prepared using a hydrophilic epoxy oligomer (HEO‐144) as the surfactant, which was prepared using liquid epoxy resin and poly(ethylene glycol) (PEG4000) at a molar ratio of 1.0. To enhance the stability of FLG‐modified waterborne epoxy dispersions, fumed silica was added and best stability was reached at a fumed silica content of 1.5%. Thermogravimetric analyses demonstrated enhanced thermal stability of the epoxy films after FLG modification. With FLG content of 1.0%, T5% of the modified epoxy films has been increased to 332 °C from 275 °C. Water contact angle and adsorption tests showed improved water resistance with FLG, the water contact angle increased from 49.5° to 76.2° and water adsorption decreased from 9.0% to 2.0%. Furthermore, electrochemical impedance spectroscopy tests and tafel analysis indicated that FLG greatly improved the anticorrosion performance of waterborne epoxy coatings. With a FLG content of 1.0%, modified waterborne epoxy coatings demonstrated significantly low corrosion rate, which was one eighth of that of the unmodified control. These results indicate that FLG modification can be an effective and low cost approach to enhance the anticorrosion performance of waterborne epoxy coatings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46743.