Back SearchTitle: HIGH STRAIN RATE RESPONSE OF S2-GLASS/EPOXY COMPOSITES WITH POLYCARBONATE FACING
Page Range: p.67-80
Author(s): Vaidya U K; Kulkarni M; Hosur M V; Mayer A; Dutta P
File size: 5770K
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Issue Year: ppc
Volume: 9
Issue No: No. 2
Abstract
The effective use is examined of a transparent polycarbonate facing bonded to a composite laminate structure which acts to suppressing/delaying damage under high strain rate impact. This study involves the testing of S2-glass/epoxy composite laminates which are bonded to polycarbonate, and the use of a compression Split Hopkinson Pressure Bar to test four, six and eight layer structures, subjected to a controlled single compressive pulse, in order to derive data relating to damage evolution. The samples were tested under high strain rate impact in three directions. Results of the investigation showed that providing a polycarbonate sacrificial facing to the S2-glass/epoxy laminate is an effective way of obtaining deformation in the facing which absorbs a large portion of the incident energy, thereby minimising any delamination threat to the composite backing, and establish a basis on which to optimise the relative thickness of the facing. 15 refs.
Title: HEAT STABILITY AND DEGRADATION OF THERMOSTABLE PREPOLYMERS IN A CONTROLLED ATMOSPHERE. I: THE HEAT CYCLE OF PROPARGYLIC MONOMER HOMOPOLYMERIZATION, AND CHARACTERIZATION OF ADDUCTS
Page Range: p.81-102
Author(s): Richer S; Alamercery S; Paisse O; Raffin G; Sanglar C; Waton H; Grenier-Loustalot M F
File size: 1065K
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Issue Year: ppc
Volume: 9
Issue No: No. 2
Abstract
A number of crosslinkable heat-stable polymers have been developed including propargyl terminated resins. The liquid study of propargylic monomers during heat treatment has shown the formation of secondary phenolic products in the reaction mixture. They are in the form of propargyl-phenol and chromene-phenol, which could be the weak links in the thermal properties of the final polymers. In addition, differences are noted between the reactivities of the two monomers, which are thought to be related to the nature of the central pivot of the skeleton. Solid state analyses by FTIR and solid state crossed polarisation magic angle spinning C NMR confirmed the structure of the final polymer, and the reaction paths proposed , which enabled the heat cycle used to be validated. Thermal analyses showed that the fluorine pivot conferred the best thermal properties on the crosslinked material and influenced the reactivity and degradation mechanisms of the compounds. The degradation of the crosslinked compounds occurred as a single step for the dipropargyl ether of bisphenol A, and as two steps for the dipropargyl ether of hexafluorobisphenol A. 19 refs.
Title: HEAT STABILITY AND DEGRADATION OF THERMALLY STABLE PREPOLYMERS IN A CONTROLLED ATMOSPHERE. II: HEAT STABILITY AND DEGRADATION OF ACETYLENE-CHROMENE TERMINATED PREPOLYMERS
Page Range: p.103-120
Author(s): Richer S; Alamercery S; Paisse O; Raffin G; Sanglar C; Waton H; Grenier-Loustalot
File size: 929K
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Issue Year: ppc
Volume: 9
Issue No: No. 2
Abstract
The heat stability and thermal degradation of two acetylene-chromene terminated polymers were investigated under controlled conditions, and the environmental impact of their degradation was studied in order to predict their remediation and fate after use. Degradation of the polymers was followed by dynamic thermogravimetric analysis. Degradation residues were analysed by FTIR, and volatile organic compounds released by pyrolysis were analysed by pyrolysis/thermal desorption cold trap/gas chromatography/mass spectrometry. Analysis of the resulting data enabled mechanisms of thermal degradation of the materials studied to be proposed in the temperature range of 250 to 550 degrees C. 10 refs.
Title: DYNAMIC MECHANICAL AND THERMAL ANALYSIS OF REACTIVE POLY (BUTADIENE-CO-ACRYLONITRILE) RUBBER-MODIFIED POLYBENZOXAZINE RESIN
Page Range: p.121-134
Author(s): Ishida H; Lee Y-H
File size: 569K
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Issue Year: ppc
Volume: 9
Issue No: No. 2
Abstract
Thermosetting polybenzoxazine resin is modified by an amine-terminated poly(butadiene-co-acrylonitrile) rubber which is chemically incorporated into the benzoxazine precursor prior to polymerisation. This synthesis route with reactive functional rubber is to minimise the adverse effects caused by the large differences in structures and properties between the matrix phase and modifier. After the thermally induced ring-opening reaction, a mixture of two network structures was formed. Dynamic mechanical analysis was used to study the relaxation behaviour in different temperature regions, and thermal properties of the modified system were examined by differential scanning calorimetry and thermogravimetric analysis. 25 refs.
Title: THERMAL FATIGUE IN CARBON FIBRE POLYMER-MATRIX COMPOSITES, MONITORED IN REAL TIME BY ELECTRICAL RESISTANCE MEASUREMENTS
Page Range: p.134-140
Author(s): Wang S; Chung D D L
File size: 525K
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Issue Year: ppc
Volume: 9
Issue No: No. 2
Abstract
Thermal fatigue in a continuous carbon fibre epoxy matrix composite was monitored in real time during thermal cycling between 28 and 118 degrees C. by measurement of the contact electrical resistivity of the interlaminar interface. Simultaneous monitoring of the temperature by the same resistivity measurement also took place. A temperature increase caused the resistivity to decrease reversibly within each thermal cycle, while thermal fatigue caused the resistivity to increase, it was found. The increase took the form of a spike increase at the maximum temperature of a cycle in an early stage of fatigue and took the form of an abrupt increase of the baseline in a later stage of fatigue. Simultaneous monitoring of temperature and thermal damage during thermal fatigue is shown to be valuable, since it provides information on exactly which point of which temperature cycle at which damage occurs. 14 refs.
Title: INTERLAMINAR FRACTURE PROPERTIES OF CARBON FIBRE/EPOXY MATRIX COMPOSITES INTERLEAVED WITH POLYETHYLENE TEREPHTHALATE (PET) FILMS
Page Range: p.141-145
Author(s): Jian W J; Tjong S C; Chu P K; Li R K Y; Kim J K; Mai Y W
File size: 516K
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Issue Year: ppc
Volume: 9
Issue No: No. 2
Abstract
The interlaminar fracture behaviour of unidirectional carbon fibre epoxy laminates with and without PETP interleaving films, and with and without plasma surface treatment was studied. Comparisons are made of the initiation values of mode I and mode II interlaminar fracture toughness for composites with and without interleaves. It is shown that interleaves have a detrimental effect on interlaminar fracture toughness with different modes of fracture, and that plasma treatment is effective in mitigating the toughness reduction in mode I, but that the interleaves improve the corresponding toughness in mode II, with a negligible influence of plasma treatment. The major failure mechanisms associated with the presence of interleaves are discussed. 17 refs.