Thermal Properties of Polyester/Epoxy Blend

Unsaturated polyester toughened Epoxy was developed. Epoxy resin had toughened by weight fraction of 10, 20, 30, and 40 wt. % unsaturated polyester. FTIR spectroscopy has been used to investigating the intermolecular hydrogen bonding. Unsaturated polyester–epoxy matrices were characterized for their thermal properties. The FTIR test detected a peak shift of the functional groups which can explain cross-linking occurs between the two resins. The crosslinking between epoxy and unsaturated polyester confirmed via the existence of the stretching asymmetrical C-C band and contraction of the C-O band. The DSC test demonstrated that glass transition temperature value decreases with epoxy strengthening. The specific heat capacity and thermal conductivity have been affected the unsaturated polyester percentage. Thermal conductivity, specific heat capacity and thermal effuisivity increased by weight fraction of polyester. The thermal diffusivity values of blends showed a little decreasing.

Sulfone-functionalized poly(p-phenylene terephthalamide) copolymer fibers with improved interfacial adhesion to epoxy matrices

The poor interfacial adhesion of aramid fiber and matrix limits the application of the final composites. In this study, a series of the sulfone-functionalized poly( p-phenylene terephthalamide) (SPPTA) copolymers were satisfactorily synthesized and the effects of polymerization conditions (contents of the additional monomer and the cosolvent LiCl, molar concentration and ratio of the monomer, reaction temperature and time) on the molecular weight of the copolymer were discussed. The introduction of the sulfone group in aromatic polyamides not only increased the polarity of poly( p-phenylene terephthalamide) (PPTA) but destroyed the regular arrangement of the molecular chains, which greatly improved the surface free energy and the solubility of the polymers in organic solvents. The polymer maintained excellent thermal and interfacial properties. Compared with the PPTA fiber/epoxy composites, the interfacial shear strength (IFSS) of SPPTA fiber-reinforced epoxy composites reached 43.5 MPa, with a significantly enhancement of 20.8%, implying that the study provided an effective method to achieve highly interfacial adhesion of aramid fiber-reinforced composites.

INFLUENCE OF UV RADIATION ON PHYSICAL-MECHANICAL CHARACTERISTICS OF FILAMENT-WOUND EPOXY GFRP BASED ON EPOXY MATRICES

The effect of ultraviolet radiation on the physical-mechanical characteristics of filament-wound glass-fiber reinforced plastic (GFRP) based on an epoxy matrix has been studied. During 45 days, a decrease in strength of GFRP when stretching and bending takes place. However, the compressive strength increases. IR spectroscopy has shown that the change in the properties of composites occurs as a result of photo-oxidative degradation of the epoxy matrix.

THE USE OF THERMOSETTING MATRICES FOR THE MANUFACTURE OF POLYMER COMPOSITE MATERIALS BY THE NON-AUTOCLAVE MOLDING METHODS

In work, the rheological heat-resistant and elastic-strength characteristics of thermosetting systems developed at FSUE «VIAM» (epoxy matrices of grades VSE-20, VSE-30, VSE-33, bismaleimide grade VST-57 and cyan ester matrices of grades VST-1210 and VST-60) processed by non-autoclave technologies. These resins make it possible to obtain composite materials for structural purposes with an operating temperature from -60 to 250 °C by the methods of vacuum infusion, impregnation under pressure and film technology. The work also presents glass transition temperatures and mechanical properties of carbon and fiberglass plastics obtained on their basis.

Build-To-Specification Vanillin and Phloroglucinol Derived Biobased Epoxy-Amine Vitrimers

Epoxy resins are widely used in the composite industry due to their dimensional stability, chemical resistance, and thermo-mechanical properties. However, these thermoset resins have important drawbacks. (i) The vast majority of epoxy matrices are based on non-renewable fossil-derived materials, and (ii) the highly cross-linked molecular architecture hinders their reprocessing, repairing, and recycling. In this paper, those two aspects are addressed by combining novel biobased epoxy monomers derived from renewable resources and dynamic crosslinks. Vanillin (lignin) and phloroglucinol (sugar bioconversion) precursors have been used to develop bi- and tri-functional epoxy monomers, diglycidyl ether of vanillyl alcohol (DGEVA) and phloroglucinol triepoxy (PHTE) respectively. Additionally, reversible covalent bonds have been incorporated in the network by using an aromatic disulfide-based diamine hardener. Four epoxy matrices with different ratios of epoxy monomers (DGEVA/PHTE wt%: 100/0, 60/40, 40/60, and 0/100) were developed and fully characterized in terms of thermal and mechanical properties. We demonstrate that their performances are comparable to those of commonly used fossil fuel-based epoxy thermosets with additional advanced reprocessing functionalities.

Study of Mechanical Properties of Hemp Fiber Composites for Electric Bicycle Frames

Electric bicycles are one of the two-wheeled transportation that has been widely used. The structure of the bicycle is generally composed of several components, one of which is the frame. The frame serves to support the load on the bicycle. At present, many changes in design, geometry and bicycle-forming materials have been carried out. In general, bicycle frames are made of metal and alloy because they have good strength to support the load of the driver. Lately, the use of composites has begun to develop as a bicycle frame material, because the frame of the bicycle has become lighter but still has the strength to support the load. This paper presents a study of the structure of electric bicycles using composite material based on epoxy matrices with rami fiber reinforcement. This study used an experimental and simulation method by designing composite laminates with A(90o/90o/90o), B(90o/45o/90o), and C(45o/45o/45o) fiber webbing layout and then carried out free compressive strength (UCS), optical microscopy and simulation using ANSYS 19.0 software. The results obtained are composite laminate design with a woven fiber layout (45o/45o/45o) having the highest strength value with a compressive stress value σ=58.64 MPa in the axial compressive plane, and σ=1.539 MPa in the tangential compressive plane. Likewise, the simulation results also obtained the highest strength in the webbing design (45o/45o/45o) which is equal σs=58.72 MPa in the axial compressive plane and σs=1.531 MPa in the tangential compressive plane.

The use of the phosphor of phosphogypsum as a filler for fluorescent polymers

In modern Russia and the CIS countries, phosphogypsum waste is an urgent environmental problem. This product is obtained in the production of phosphoric acid and is a large tonnage of low-recyclable waste. According to open sources, it is processed 20 times less than it is produced. Attempts to use it in cement production, in construction, in agricultural purposes do not lead to a cardinal fracture and it is still accumulating. In this regard, the topic of processing and use of phosphogypsum is an urgent topic. In the modern world there is a demand for bright luminescent colors, paints, consumer goods. An analysis of the literature showed that phosphors can be made from various chemicals, including metal sulfides. The purpose of the work is to study the possibility of obtaining a phosphor from phosphogypsum and its use as a filler-pigment for polymer products. The phosphor was obtained from phosphogypsum by the reduction of phosphogypsum with an organic substance. This phosphor was studied in polyethylene, polypropylene, polystyrene and other polymer matrices. It is shown to be compatible with polyolefins, polystyrene, polyvinyl chloride, nitrocellulose matrices; not compatible with epoxy matrices. It is shown that at the melting temperature of polymers this phosphor does not decompose, does not lose its properties. As a result of the work, conclusions were drawn about the possibility of obtaining a cheap phosphor filler, which is compatible with many industrial polymers. This phosphor can be used in toys, in the manufacture of special luminescent paint and consumer goods..