Đánh giá khả năng bảo vệ thép của lớp phủ polyurea đi từ aspartic este gốc 4,4′-metylenbis-(2-metylcyclohexylamin)

An aspartic ester was synthesized from 4,4'-methylenebis (2-methylcyclohexylamine), diethyl maleate and mono-epoxy. The method of synthesis, properties and structure of this material has been studied and published [1]. Aspartic ester mixed with additives to produce a 2-component polyurea coating system. Polyurea coating from aspartic ester cured by Desmodur N 3600 undergoes accelerated tests of environmental degradation by salt-fog and Q-sun. The metal protection capacity of the polyurea coating was evaluated through image, mechanical properties and electrochemical impedance before and after environmental acceleration. Keywords. Polyurea, aspartic ester, metal coating, coating protection

Tính chất cơ học của vật liệu compozit sử dụng prepreg trên cơ sở nhựa phenolic và epoxy gia cường sợi thủy tinh và thủy tinh-aramit

Prepreg composite materials are becoming increasingly common in the industry due to their ease of use, consistent properties and high surface quality. However, there is much to understand about prepreg prior to committing to using this material. Therefore, in this paper phenolic resin (rezolic) and two compositions, including solid epoxy resin DER633U/Hardener DEH84 and epoxy Epikote 828/Hardener Novolac have been investigated for preparing glass fiber and glass-aramid fibers reinforced prepregs. Results showed that all single resin and compositions mentioned above are satisfied technical requirements for prepregs. The best prepreg was made by composition DER633U/DEH84 because it possesses good shelf life at temperature 36-37 oC and high composite mechanical properties. For example, tensile strength 205.2 MPa and Izod impact strength 228.9 KJ/m2 with C-glass fabric reinforcement 360 g/m2

Nghiên cứu chế tạo vật liệu polyme compozit từ hệ nhựa epoxy/DDS gia cường sợi thủy tinh có mặt vi sợi xenlulo. Phần 4. Ảnh hưởng của vi sợi xenlulo hình thành do vi khuẩn đến tính chất cơ học và độ bền mỏi của vật liệu polyme compozit từ nhựa epoxy

The aim of this study is to investigate the influence of bacterial cellulose (BC) content on the damage mechanisms of glass fibers reinforced epoxy under fatigue loading cycles and some other mechanical properties. Specimens were manufactured from prepregs to keep exact glass fibers/epoxy ratio. The mechanical properties of the materials such as tensile strength, flexible strength were affected slightly by the adding of BC. The fatigue life, however, increased significantly for 0.3% BC content of glass fibers reinforced epoxy. Scanning electron microscopy-analysis revealed the different deformation of the matrix due to the BC.

Nghiên cứu ảnh hưởng của nanosilica đến tính chất cơ học của màng polyme epoxy DER 671X75.

Study on the effects of silica nanoparticles (nanosilica) and modified nanosilica to mechanical properties of polymer coating film based on epoxy resin DER 671X75. Surface modification of nanosilica by 3-aminopropyltriethoxy silan (APTES) was characterized by Fourier Transform Infrared Spectrometry (FTIR), Scanning Electron Microscopy (SEM) and Thermo Gravimetric Analysis (TGA). Dispersions of nanosilica and modified nanosilica in epoxy resin DER 671X75 were carried out by stirring and ultrasonic vibration. The structures of the materials were characterized by SEM. The mechanical temperature properties were chacrcterized by TGA. The results show that nanosilica and modified nanosilica are good dispersed and improved mechanical properties of polymer coating film based on epoxy resin DER 671X75. Keywords. Silica nanoparticles, nanosilica, modified nanosilica, 3-aminopropyltriethoxy silan, epoxy resin DER 671X75

Nghiên cứu ảnh hưởng của nanosilica đến tính chất cơ học của màng polyme polyurea trên cơ sở polyaspartic este desmophen NH1520 đóng rắn bằng Desmodur N3600

The effects of silica nanoparticles (nanosilica) to mechanical properties of polymer coating film polyurea based on polyaspartic ester resin Desmophen NH1520 and hardener Desmodur N3600 have been studied. Surface modification of nanosilica was realized by 3-amino propyl triethoxy silan (APTES). Dispersions of nanosilica in polyaspartic ester resin Desmophen NH1520 were carried out by stirring and ultrasonic vibration. The structures of the hybrids were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thermal properties were characterized by thermo gravimetric analysis (TGA). The results show that nanosilica is good  dispersed and improved mechanical properties of polymer coating film polyurea based on polyaspartic ester resin Desmophen NH1520. Keywords. Polyurea resin, polyaspartic ester resin Desmophen NH1520,  silica nanoparticles, nanosilica, modified nanosilica

Độ bền dai tách lớp và tính chất cơ học của vật liệu polyme compozit trên cơ sở nhựa epoxy epikote 828/OELO gia cường sợi cacbon, đóng rắn bằng xyanetyldietylentriamin

Carbon fabric/epoxy (CF/EP) composite toughened by OELO was prepared to improve fracture toughness of the composite. The obtained testing results showed that the Izod impact strength of carbon fabric/epoxy composites significantly increased by 31.4 % from 37.2 KJ/m2 to 48.9 KJ/m2 just by adding 6 phr (part per hundred of resin) OELO was dispersed in the epoxy matrix. Both mode-I interlaminar fracture toughness of carbon fabric/epoxy (OELO/EP) composites at crack initiation and propagation also improved by 37.2 % and 17.7 %, respectively by content of 6 phr OELO in compositions. Damaged surfaces of fractured samples were investigated using scanning electron microscopy (SEM) techniques. Results obtained from dynamic mechanical thermal analysis (DMTA) showed that the glass transition temperatures of the epoxy resin matrix were slightly reduced on the addition of 6phr OELO. Keywords. Epoxy resin, fracture toughness, epoxidized linseed oil oligomer, composite materials

Chế tạo vật liệu compozit sinh học trên nền nhựa polyeste không no gia cường bằng sợi nứa có xử lý bổ sung plasma lạnh

After extracting by mechanical (by hand) and machine methods, Neohouzeaua fiber was treated by air plasma at atmospheric pressure with conditions of power 100W, frequency of 17 kHz and different treatment times (from 1 min to 7 min). SE M analyses showed that the fiber surface become rougher after plasma treatment because of the effect of plasma bombardment and etching. The testing on tensile strength and the interfacial shear strength (IFSS) showed that at the optimal treatment time of 4 minutes: the tensile strength of neohouzeaua fiber increased 15.5 percent after air plasma treatment and treated fiber have cleaner surface. IFSS of the treated fiber at 4 minutes increased 51.7% compared with untreated fiber. Unsaturated polyester (USP) resin composites reinforced by neohouzeaua fiber submitted to air plasma treatment and untreated and USP composites reinforced by hybrid neohouzeaua/glass fiber mat were fabricated using a vacuum infusion process (VIP). Mechanical test, SEM and water absorption measurements of the composites have been investigated. These results reveal that atmospheric pressure air plasma treatment is an effective method to improve not only the performance of neohouzeaua fiber but also of UPS-neohouzeaua composites. With hybrid composites with ply-by-ply structure and the content ratio of neohouzeaua/glass of 40/60 (by weight) the received materials has optimal properties, such as tensile, flexural and impact strengths improve 38.9%, 15.5% and 217.5% compare to PC-Neohouzeaua mat, respectively