印制板用的耐热性环氧—硅复合树脂基材

概述了基于新概念的环氧-硅复合树脂的开发,并证实了传统FR-5基材的制造工艺可以适用于环氧-硅复合树脂的覆铜箔板制造。

氟硅树脂改性环氧树脂的合成及其性能研究

采用有机硅氧烷、氟硅烷合成氟硅树脂,用氟硅树脂对环氧树脂进行改性,制得了氟硅-环氧复合树脂。对复合树脂的结构和漆膜的力学性能进行了分析。分析结果表明,改性后的氟硅-环氧树脂综合了氟树脂、有机硅树脂和环氧树脂的优异性能,用其制得的漆膜致密,附着力优异,硬度高,疏水性能优良。

环氧树脂及其固化剂在浇铸母线槽系统中的应用及加工工艺

环氧复合树脂作为一种新型绝缘材料,应用于母线槽系统中,可以达到更高的耐火、防腐、防水和防爆性能,同时又能满足母线槽系统正常的电气性能。而环氧树脂、固化剂和添加剂恰当的配比,是达到浇注母线槽电气性能、耐火、防腐、防水和防爆性能的关键要素。本文主要阐述各相关材料的配比及固化方式和时间,同时也阐述了浇注母线的浇注工艺。

Research on High-Velocity Impact Damage Monitoring Method of CFRP Based on Guided Wave

Carbon fiber-reinforced polymer(CFRP)is widely used in aerospace applications.This kind of material may face the threat of high-velocity impact in the process of dedicated service,and the relevant research mainly considers the impact resistance of the material,and lacks the high-velocity impact damage monitoring research of CFRP.To solve this problem,a real high-velocity impact damage experiment and structural health monitoring(SHM)method of CFRP plate based on piezoelectric guided wave is proposed.The results show that CFRP has obvious perforation damage and fiber breakage when high-velocity impact occurs.It is also proved that guided wave SHM technology can be effectively used in the monitoring of such damage,and the damage can be reflected by quantifying the signal changes and damage index(DI).It provides a reference for further research on guided wave structure monitoring of high/hyper-velocity impact damage of CFRP.

Cardo poly (ether sulfone) toughened E51/DETDA epoxy resin and its carbon fiber composites

A toughener that can effectively improve the interlaminar toughness in carbon fiber composites is crucial for various applications.We investigated,the toughening effects of phenolphthalein-based cardo poly(ether sulfone)(PES-C)on E51/DETDA epoxy and its carbon fiber composites(CFCs).Scanning electron microscopy showed that the phase structures of PES-C/epoxy blends change from island(of dispersed phase)structures to bi-continuous structures(of the matrix)as the PES-C content increased,which is associated with reaction-induced phase separation.After adding 15 phr PES-C,the glass transition temperature(T_(g))of the blends increased by 51.5℃,and the flexural strength,impact strength and fracture toughness of the blends were improved by 41.1%,186.2%and 42.7%,respectively.These improvements could be attributed to the phase separation structure of the PES-C/epoxy sys-tem.A PES-C film was used to improve the mode-II fracture toughness(G_(IIC))of CFCs.The G_(IIC) value of the 7μm PES-C film toughened laminate was improved by 80.3%compared to that of the control laminate.The increase in G_(IIC) was attributed to cohesive failure and plastic deformation in the interleaving region.

氰酸酯/环氧复合体系弹性波纹板的制备及性能研究

本文通过合成制备氰酸酯/环氧复合树脂体系,对该体系的合成工艺及物理性能进行了研究,并考察了温度及催化剂用量对复合树脂反应活性的影响。以 E-玻璃纤维布为增强材料、氰酸酯/环氧复合树脂为粘结剂制备了发电机定子槽内固定用弹性波纹板,研究了不同体系的树脂及树脂含量对波纹板的变形应力和波峰变化率等性能的影响。结果表明,氰酸酯/环氧复合树脂体系弹性波纹板完全满足 SIE—MENS、GE 公司同类产品技术要求,达国内先进水平。

PF/EP/Nano-SiO_2 Composite Paint for Resistor

Phenolic resin(PF) and nano-SiO2 were used to improve the curing property and high humidity resistance of epoxy resin (EP) and methyl nadic anhydride (MNA) resistor paint, respectively. Hydrogen bonds, formed between phenolic resin and nano-SiO2 in alcohol, made nano-SiO2 disperse easily in EP/MNA paint through phenolic resin without being treated by supersonic vibration. When the mass ratio of PF to EP in paint is 3:7, the formed composite paint film can be cured in 2 min at 170 ℃ . When the mass ratio of nano-SiO2 to PF in paint is 3:100, the property of high humidity resistance of the composite paint is the best, meeting the requirement of varying ratio of resistance less than 0.1% after experiment on high humidity resistance. SEM analysis shows the surface of the composite paint film is smooth, glassy, tight and homogeneous, without acicular air holes.

Failure Analysis in Graphite Epoxy Composite Laminates

The present analysis was performed to obtain bearing strength for pinned joints in uni-directional graphite epoxy composite laminates using characteristic curve model. The characteristic dimensions used to determine the characteristic curve were evaluated using a two-dimensional finite element model that was developed in ANSYS14.5 Software. Also, two-dimensional finite element stress analysis was developed to determine the stress distribution needed to evaluate the failure. Tsai-Wu failure criterion was used in the analysis with the characteristic curve to predict bearing strength. The results of the analysis showed good agreement with experimental data.

Preparation and Properties of Y_(2)O_(3)-PF Alternating Coating on Polymer Matrix Composite Material Surface

High-performance yttrium oxide-phenolic resin(Y_(2)O_(3)-PF)alternating coating was prepared on epoxy resin-based composite material using supersonic plasma spraying and dual-channel powder feeding technique.Y_(2)O_(3)-coated PF(Y_(2)O_(3)/PF)powder was firstly sprayed onto the substrate,forming a transition layer,and then the spherical Y_(2)O_(3) powder and Y_(2)O_(3)/PF powder were alternately deposited to form the composite alternating coating.Results show that the alternating coating is mainly composed of deposited Y_(2)O_(3)/PF powder.The bonding strength between coating and substrate is as high as 26.48 MPa with the single-test maximum bonding strength of 28.10 MPa,and shear strength reaches 24.30 MPa.Additionally,the heat transfer effect caused by external Y_(2)O_(3) particles gradually softens and even melts PF,thus effectively avoiding the damage of high temperature to molecular structure and thereby promoting the crosslinking and curing effects of resin during the deposition process.In the meantime,the unmelted Y_(2)O_(3) powder results in the shot peening effect,which washes out and eliminates the powder particles with inferior deposition effect,ultimately improving the physical and chemical properties of the alternating coating.

Improving interlaminar fracture toughness of flax fiber/epoxy composites with chopped flax yarn interleaving

In this research, unidirectional flax fabrics reinforced epoxy laminates were intedeaved with randomly oriented chopped flax yarns at various yarn lengths and contents. Mode I interlaminar fracture toughness of the laminates was evaluated via Double Cantilever Beam （DCB） tests. The results showed that Mode I interlaminar fracture toughness increased with the introduction of the chopped yarns. With moderate yarn length and content, the best toughening effect （31% improvement in Mode I inter- laminar fracture toughness） was achieved. It was observed with the aid of Scanning Electronic Microscopy （SEM） that the in- troduction of the chopped yarns resulted in more tortuous in-plane crack propagation paths as well as the ＂trans-layer＂ phe- nomenon and fiber bridging effect of both the unidirectional yams and the chopped yams. These hindered the growth of the crack and led to more energy dissipation during delamination progress. Excessive yam length or content would induce unstable crack propagation and thus weakened the toughening improvement. No remarkable change was found in the tensile properties and the Charpy impact strength for the interleaved laminates, which indicated that this interleaving method was effective on interlaminar toughening without sacrificing the comprehensive mechanical properties of the laminates.

Mechanical and thermal properties of mesogen-jacketed liquid crystalline polymer/epoxy resin composites

The effects of mesogen-jacketed liquid crystalline polymer poly(dipropyl vinylterephthalate)(PDPVT) on the mechanical and thermal properties of diglycidyl ether of bisphenol-A(DGEBA) epoxy resin were investigated by impact test, tensile test and thermogravimetric analysis(TGA). The mechanism underlying the enhancement of mechanical properties of epoxy resin was studied using 1D wide-angle X-ray diffraction(WAXD) and scanning electron microscope(SEM). It was found that the mechanical properties of 1 wt%–5 wt% PDPVT/DGEBA composites were significantly improved compared to neat epoxy resin. Especially, the epoxy resin with 3 wt% PDPVT had the greatest increase in mechanical properties, with the impact strength, tensile strength and elongation while breaking increased by 87%, 59% and 174%, respectively. The increased mechanical strength was due to the fact that PDPVT maintained liquid crystalline phase in cured PDPVT/DGEBA composites, which would blunt the crack tip and prevent crack propagation. Moreover, PDPVT had slight effect on the thermal stability properties of epoxy resin.

Low velocity impact response and energy absorption behavior on glass fibre reinforced epoxy composites

A study was undertaken to determine the effects of several key geometry influencing factors on the impact response and energy absorption behavior of the glass fibre reinforced epoxy composites at low and intermediate energies.The energy-balance model was employed for characterising the energy absorption behavior and it depends strongly on the plate diameter and thickness.In addition,the damage vs.energy and force maps is effective in monitoring damage growth within the composite panel.The response of the composite laminate configurations characterized by different stacking sequences subjected to low velocity impacts with different impact energies have also been studied to estimate the damage initiation of composites.

Analytical investigations and fuzzy logic-based modeling of the impact resistance of aluminum-epoxy laminated composites

In the present paper, Charpy impact resistance of aluminum-epoxy laminated composites in both crack divider and crack ar-rester configurations has been investigated. In both configurations, an analytical investigation has been carried out to evaluate the effects of layers thickness on impact resistance of the specimens. A model based on fuzzy logic for predicting impact re-sistance of the specimens has been presented. For purpose of building the model, training and testing using experimental re-sults from 126 specimens produced from two basic composites were conducted. The data used for the input data in fuzzy logic models are arranged in a format of 7 input parameters that cover the thickness of layers, the number of layers, the adhesive type, the crack tip configuration, the content of SiC particles, the content of methacrylated butadiene-styrene particles and the number of test trial. According to these input parameters, in the fuzzy logic model, the impact resistance of each specimen was predicted. The training and testing results in the fuzzy logic model have shown a strong potential for predicting impact resis-tance of aluminum-epoxy laminated composites.