Curing Behavior of Epoxy Asphalt

The curing process of epoxy asphalt was analyzed by Fourier transform infrared （FT-IR） spectroscopy. Effect of curing temperature on viscosity of epoxy asphalt, and changes of mechanical properties with curing time were investigated. The evolution of concentration of epoxy band was followed as a function of the applied curing process.The experimental results indicate that the curing reaction rate of epoxy asphalt is invariable before 70 min at 120 ℃, and it decreases when curing time exceeds 70 min. The viscosity of epoxy asphalt increases slowly with curing time at initial curing stage. But it increases quickly after initial curing stage and the initial curing time decreases as the curing temperature increases, The tensile strength increases slowly at incipient curing stage and increases rapidly when curing time is form 20 min to 70 min. The elongation at break shows a decrease with curing time, but it exceeds 200% after cured.

Synthetic Process of Bio-Based Phenol Formaldehyde Adhesive Derived from Demethylated Wheat Straw Alkali Lignin and Its Curing Behavior

Lignin is a natural biopolymer with a complex three-dimensional network, commercially obtained from wasteliquid of paper pulp and bioethanol production, and could be a candidate for preparation of environment-friendlybio-based polyphenol material. In the present work, the demethylated wheat straw alkali lignin (D-Lig), preparedby demethylation of wheat straw alkali lignin (Lig) using an in-situ generated Lewis acid, was used to synthesizebio-based phenol formaldehyde resin adhesive (D-LPF) applied in plywood. Effects of synthetic process’s factors,including lignin substitution for phenol, NaOH concentration and molar ratio of formaldehyde to phenol, on thebonding strength and free formaldehyde content of D-LPF were investigated in detail, and the optimum syntheticprocess of D-LPF was obtained as following: Lignin substitution for phenol 60%, NaOH concentration 5.0% andmolar ratio of formaldehyde to phenol 2.0, and under the optimum reaction condition, the D-LPF presented lower free formaldehyde content (0.18%) and higher bonding strength (2.19 MPa), which was better than those ofcontaining-lignin phenol formaldehyde resin adhesive (LPF). Additionally, the curing behavior of the adhesivewas studied by differential scanning calorimetry (DSC) combined with gel time. It can be obtained that D-LPFresin adhesive had the shortest gel time, and fastest curing rate, compared with those of PF and L-PF resin adhesives. The curing kinetics data was fitted well by Kissinger model using non-isothermal DSC method, and theaverage activation energy value was 85.3 kJ/mol, slightly higher than that of commercial PF resin, while lowerthan that of LPF (90.2 kJ/mol). Finally, based on the analytical results of high temperature fourier transform infrared spectroscopy (FTIR), a possible curing mechanism of D-LPF was proposed.

Curing Behaviors and Thermal Properties of Dimer Fatty Acid （DFA） Modified Multifunctional Epoxy Resin

In order to improve the toughness of the cured aromatic tetrafunctional epoxy resins, a dlmer rarboxylic acid named dlmer fatty acid （DFA） was used to modify an aromatic tetrafunctional epoxy, N, N, N＇, N＇-tetraglycidyl-2,2-bis [ 4-（ 4-aminophcuoxy ） phenyl ] propane （TGBAPP）. The curing behaviors of DFA- TGBAPP/MNA （ methyl nadic anhydride） systems were studied by differential scanning calorimetry （DSC） method. And the thermal properties of the cured epoxy resin were investigated with the thermo-gravimetric analysis （TGA） and dynamic mechanical analysis （DMA）. Besides, the toughness was characterized with the impact strength tested by charpy impact testing. The results indicated that the modification would improve the curing reactions, and the curing temperatures were decreased with the increasing content of DFA. The thermal properties were not influenced obviously, and the toughness could be improved when the epoxy resin was modified with DFA.

Synthesis and curing of a novel amino-containing phthalonitrile derivative

A novel phthalonitrile derivative containing an amino group, 3,5-bis（3,4-dicyanophenoxy）aniline （CPA）, was synthesized via a nucleophilic displacement of 4-nitrophthalonitrile and 5-aminoresorcinol hydrochloride. The structure of CPA was confirmed by Fourier transform infrared spectra （FT-IR） and nuclear magnetic resonance （^1H NMR）. Thermal analysis performed on CPA revealed that the novel phthalonitrile derivative showed a self-promotion curing behavior and the resulting polymer exhibited outstanding heat-resistance.

Study on Cure Behavior of a Model Epoxy System by Means of TTT Diagram

Curing behavior of a model epoxies system (E-54/AG-80) with DDS as hardener was studied in this paper. Round disk compression mode DMA was executed to study the gel behaviors at different temperatures to determine the relationship between gel-time (t_ gel) and temperature. The cure kinetics was studied by dynamic DSC analysis. Parameters were obtained for establishing a phenomenological cure reaction model. The relationship between glass transition temperature (T_g) and cure degree (α) was also analyzed by both isothermal and dynamic DSC method based on DiBenedetto equation, which gave a mathematical description of T_g as a function of both time and temperature. Consequently, characteristic temperatures such as T_ g0, gelT_ g and T_ g∞ were determined. Finally, the Time-Temperature-Transition (TTT) diagram was designed based on the data and equations.

Phthalonitrile-PPO Blends: Cure Behavior and Properties

Hydroxy-containing low molecular weight poly（2,6-dimethyl-1,4-phenylene oxide）（r PPO） and self-promoted hydroxycontaining phthalonitrile（HPPH） were prepared by redistribution reaction and the simple nucleophilic displacement of a nitro-substituent from 4-nitrophthalonitrile in a dipolar aprotic solvent respectively. The hydroxy-containing phthalonitriles modified by r PPO were prepared by mechanical blending without compatibilizer, followed by heating. The curing behavior was studied using dynamic rheological analysis, and the results showed that the r PPO-modified phthalonitrile exhibited a large processing window（over-67 °C） and complex viscosity（0.18-0.8 Pa·s） at moderate temperatures. After curing at 300 °C, the resulting polymers showed good thermal stability and high modulus as observed by thermogravimetric analysis（TGA） and dynamic mechanical analysis（DMA）. The dielectric properties and the morphology of r PPO-modified phthalonitrile networks were studied by dielectric analysis and field-emission scanning electron microscopy（SEM）.

Thermosetting resin modified asphalt:A comprehensive review

Thermosetting resins have advantages such as high strength,corrosion resistance,and aging resistance,and have excellent prospects for practical application as asphalt modifiers.In order to promote the research of thermosetting resin modified asphalt,to provide direction for its further research,this paper reviews the research progress of thermosetting resin modified asphalt in recent years.The material composition,modification mechanism,and curing behavior of epoxy asphalt,thermosetting polyurethane modified asphalt,unsaturated polyester modified asphalt,and other thermosetting resin modified asphalts are overviewed.Different types of thermosetting resin modified asphalt have different performances,the performance advantages of different thermosetting resin modified asphalts are summarized.At the same time,the existing problems in thermosetting resin modified asphalt and further research directions are provided.Encouraging researchers to produce thermosetting resin modified asphalts using waste or bio-based materials,and to study the recycling technologies and life cycle assessment of thermosetting resin modified asphalt.This paper provides a reference for the study of thermosetting resin modified asphalt.

Synthesis, Characterization of Phosphorus Containing Diamide-diimide-tetraamines Based on L-Tryptophan Amino Acid and Their Effect on Flame Retardancy of Epoxy Resins

The curing behavior of diglycidyl ether of bisphenol-A （DGEBA） with different phosphorus containing diamidediimide-tetraamines （DADITAs） was studied by DSC. Eight DADITAs of varying structures were synthesized by reacting 1 mole of pyromellitic anhydride （PMDA）/3,3＇-benzophenone tetracarboxylic dianhydride （BTDA）/1,4,5,8-naphthalene tetraearboxylic dianhydride （NTDA）/4,4＇-oxydiphthalic anhydride （ODPA） with 2 mole of L-tryptophan （T） in a mixture of acetic acid and pyridine （3：2 V/V） followed by activaton with thionyl chloride and then condensation with excess of phosphorus containing triamines tris（3-aminophenyl） phosphine （TAP） and tris（3-aminophenyl） phosphine oxide （TAPO）. DADITAs obtained by reacting PMDA/BTDA/NTDA/ODPA with L-tryptophan followed by condensation with TAP/TAPO were designated as PTAP, PTAPO, BTAP, BTAPO, NTAP, NTAPO, OTAP and OTAPO respectively. The structural characterization of synthesized DADITAs was done by FTIR, ~H-NMR, I3C-NMR, 31p-NMR spectroscopic techniques and elemental analysis. Thermal stability of the isothermally cured epoxy was investigated using dynamic thermogravimetry analysis. The glass transition temperature （Tg） was highest in DGEBA cured using PTAP. All epoxy thermosets exhibited excellent flame retardancy, moderate changes in Tg and thermal stability. Due to presence of phosphorus in curing agents, all epoxy resin systems met the UL-94 V-0 classification and the limiting oxygen index （LOI） reached up to 38.5, probably because of the nitrogen-phosphorus synergistic effect.