ISSN:0272-8397    

DOI:10.1002/pc.750010202

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe amounts of resin weight loss and fiber weight loss in four PMR polyimide/graphite fiber composites were calculated from the composite weight losses and the fiber/resin ratios of the composites after long term thermo‐oxidative aging in 600° F air. The accelerating effect of graphite fiber on resin weight loss, compared to neat resin weight loss, indicated the presence of a deleterious resin/fiber thermo‐oxidative interaction, presumably due to fiber impurities. Similarly, the declerating effect of the protective matrix resin on fiber weight loss, compared to bare fiber weight loss, was also demonstrated. The amount of hydrazine indigestible resin and the amount of loose surface graphite fiber that formed during 600° F exposure of the composites were quantitatively determined. The indigestible residual resin was also qualitatively studied by scanning electron micro

ISSN:0272-8397    

DOI:10.1002/pc.750010203

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractMonoepoxy phenyl glycidyl ether, curing agent p‐chloroaniline, and the substituted urea type accelerator Monuron were used as a model system for studying the amine cure of epoxies. Reactions were carried out at 120°C with amine to epoxy equivalent rations of 0.25 and 1.0 Reaction mixtures were analyzed primarily by reverse phase high performance liquid chromatography. Three types of reactions occur; simple amine addition to epoxy, homopolymerization of epoxy, and epoxy polymerization involving the addition products. In the absence of accelerator the reaction involved simple addition. With the accelerator, there was competition between addition and polymerization, the balance depending on the amine to epoxy equivalent ratio. Both addition and polymerization were important for a ratio of 1, but polymerization far outweighed addition for a ratio of 0.

ISSN:0272-8397    

DOI:10.1002/pc.750010204

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe effect of stress on the diffusion of water in glassy polymers is analytically treated. Utilizing the free volume concept the effect of stress on the free volume fraction is established and in turn is related to the diffusion coefficient yielding the following formula:Dσ=Doe(6 to 10)σ/GwhereDσandDoare the diffusion coefficients in the presence and absence of stress respectively,Gis the shear modulus, and σ is the stress. Experiments are described which demonstrate that in a bent epoxy bar, more water is picked up at the tension side than at the compression side. Theory and experiment are discussed and compa

ISSN:0272-8397    

DOI:10.1002/pc.750010205

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractLiquid size exclusion, adsorption, and bonded‐phase high performance liquid chromatographic (HPLC) methods have been developed to monitor the chemical compositions of epoxy resin prepregs. Examples are given to illustrate how multiple detectors and oligomer analysis techniques may be used to identify prepreg components and to discriminate between epoxy resins obtained from different manufacturers. The results of a case study in which HPLC methods were used to monitor compositional variations in batches of a commercial prepreg over a four year period are discussed. Finally, examples demonstrate how HPLC may be applied to monitor prepreg aging and to measure the extent of prepreg stagin

ISSN:0272-8397    

DOI:10.1002/pc.750010206

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe chemical reactions at the interface between an anhydride‐cured epoxy resin and an aminosilane treated fiber have been investigated using Fourier transform infrared methods (FT‐IR). The results indicate that chemical bonds are formed in the interfacial region between the matrix and the coupling agents. The amount of interfacial bonding depends on the composition and the processing conditi

ISSN:0272-8397    

DOI:10.1002/pc.750010207

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractDifferential thermal contraction between matrix and fiber materials in composites and between adhesive and adherend materials in adhesive joints occurs during cooling from the resin cure temperature and gives rise to non‐uniform internal stress fields. Resin swelling associated with water uptake during service gives rise to inhomogeneous stress, the magnitude and distribution of which is the subject of the present investigation. Thin layers of cured epoxy resin have been allowed to absorb water at their edges only, and the swelling normal to these layer planes has been measured by studying optical interference patterns. The stresses resulting from inhomogeneous swelling, a few tens of bars, are of similar magnitude to those resulting from inhomogeneous shrinkage during cooling from resin cure temperature

ISSN:0272-8397    

DOI:10.1002/pc.750010208

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractThe torsional braid analysis (TBA) equipment has been used as an automated torsion pendulum to characterize prepreg materials in the form of single ply strips (2‐1/2 × 1/8 in.). Compared to the use of coated glass braids, the main difference was a marked weakening of the gelation mechanical damping peak in isothermal runs. However, prepreg materials consisting of epoxy resins on glass, carbon or aramid fibers were successfully run isothermally to provide gelation and vitrification times as a function of temperature, or in constant heating rate scans to reveal theT

ISSN:0272-8397    

DOI:10.1002/pc.750010209

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

摘要:

AbstractRecently, there has been concern over the effects of accidentally released conductive carbon and graphite fibers on unprotected electrical circuits. Because of their thermal stability, such fibers could be released by the involvement of a resin matrix composite in a fire. A simple method based on thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) has been developed which permits the assessment of release potential from such composites. Dynamic TGA is used to determine temperatures at which significant events such as onset of resin matrix decomposition occur. Isothermal TGA permits a determination of the time required to produce releasable fibers at a given temperature. SEM examination of residues from TGA experiments serves to characterize their physical state which, in turn, permits a more precise assessment of release potential. This method has been used to examine a large number of materials composed of several different fibers in a variety of thermoset and thermoplastic matrices. It is concluded that release potential varies inversely with resin thermal‐oxidative stability and directly with fiber stability. The matching of matrix resin char and fiber stabilities is especially effective in suppressing fiber releas

ISSN:0272-8397    

DOI:10.1002/pc.750010210

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY

ISSN:0272-8397    

DOI:10.1002/pc.750010201

出版商:Society of Plastics Engineers, Inc.    

年代:1980

数据来源: WILEY