Composites Manufacturing最新文献

A novel process has been developed to manufacture pultruded fibre-reinforced furfuryl alcohol (FA) resin composites. In this paper, the effects of fibre reinforcement type and content on the static, dynamic mechanical and thermal properties of the FA resin pultruded composites are investigated. The mechanical properties increase with increasing volume content of the glass or carbon fibres, with the glass fibre-reinforced furfuryl alcohol (GF/FA) composite exhibiting maximum mechanical property values at a filler content of 5 phr. High catalyst content and die temperatures are necessary for manufacturing FA pultruded composites with high filler content. GF/FA pultruded composites retain their mechanical properties at elevated temperatures better than do unsaturated polyester pultruded composites. Dynamic mechanical analysis revealed that the dynamic storage modulus of the GF/FA pultruded composites increases with increasing post-cure time. Tan δ of GF/FA decreases and its glass transition temperature increases with decreasing pulling rate or increasing post-cure time. The glass and carbon fibre-reinforced FA pultruded composites possess high heat distortion temperature and good flexural properties, in comparison with other pultruded composites.

Furfuryl alcohol (FA) prepolymer was developed to fabricate pultruded fibre-reinforced FA resin composites. FA monomer with p-toluene sulfonic acid was used to synthesize the FA prepolymer, which provided a good balance between processing parameters (including pot life, reactivity and wetting ability) and properties of the composites. The reactions occurring during synthesis of the FA prepolymers and the post-curing treatment were investigated by ¹H n.m.r. and i.r. spectroscopies. It was found that the mechanical properties of the composites increase with increasing die temperature or decreasing pulling rate. From the study on the mechanical properties of the composites, it was found that an optimum post-cure time exists when the post-cure temperature is above 200°C. It was also found that three kinds of reaction - crosslinking, chain extension polymerization and the transformation of the methylene ether linkage to a methylene linkage -occur during the post-curing treatment.

This paper deals with increasing the speed of the infra-red (IR) heating cycle in the processing of thermoplastic composites. A constraint on the heating process is that all parts of the material must be within the recommended processing temperature range before forming can start. A mathematical model is used to predict the transient temperature distribution through the thickness of flat consolidated panels of continuous carbon fibre-reinforced poly(ether ether ketone) (APC-2) during heating. The model includes (i) natural convection, (ii) medium and long wave radiation and (iii) one-dimensional conduction through the material. Experimental validation of the model is conducted using an IR test rig. The following process parameters were varied to obtain optimum process conditions: (i) heater power: (ii) heater-to-composite distance: (iii) composite thickness; (iv) degree of oversizing of heater area compared with surface area of composite: and (v) one- or two-sided heating. Results presented show that reduction of the heater-to-composite distance from 100 to 50mm increases the steady-state temperature of the composite by 88%, whereas almost doubling the heater power density from 25.6 to 47.3 kWm² - increases the composite temperature by only 17%. Using one-sided heating, experimental results show that upward-facing heaters produce a more even temperature distribution across a panel surface than downward-facing heaters. Model results showing 1 R heating times for composite panels of thickness 0.5 to 9.5 mm are also presented.

The resin transfer moulding process involves the long-range flow of resin into a closed mould which is filled with dry fibre reinforcement. The rate of resin flow can be calculated using the Darcy and Kozeny-Carman equations. The flow rate is thus a function of the pressure drop across the fibre bed, the resin viscosity and the permeability of the fibre bed. The permeability constant is dependent on the fibre radius and the porosity of the bed. A number of reinforcement fabrics are now available commercially which promote faster resin flow than that in equivalent fabrics of the same areal weight at the same fibre volume fraction. The KozenyCarman equation includes a parameter known as the mean hydraulic radius. If this parameter is varied by calculating specific hydraulic radii, then the flow enhancement may be modelled. Calculations for model materials have been published and demonstrate that this approach predicts that significant changes in flow rate are possible. The commercial fabrics do not have model structures, but feature variations in the mesoscale architecture of the reinforcement: fibres clustered into tows and uneven distribution of pore space. The paper will report on the correlation of quantitative image analysis of optical micrographs with the flow rates in a range of reinforcement fabrics.