Polymer matrix composites process development

Historically, the processing routes moved from the isothermal CVI process to more cost-effective techniques such as gradient-CVI and liquid polymer or liquid silicon infiltration. These routes are faster and lead to shorter manufacture cycles than isothermal CVI and, especially the two liquid phase processes LPI and LSI, use technologies already developed for polymer matrix composites (PMC). 

Composites are inherently difficult to recycle because they are multiphase. The two or more phases/materials that constitute the composite are normally intermixed on a very fine scale, and trying to separate them complicates the recycling process. However, some techniques have been developed, with modest success, for reoyoUng polymer-matrix composites. Recycling technologies differ only slightly for thermoset-matrix and thermoplastic-matrix composite materials. 

A significant amount of waste composites is generated each year and the need for a recycling method is becoming a necessity. Environmental Technical Services has developed, with the support of the University of Missouri-St.Louis, a method for recovering valuable constituents from composite materials. The process converts the polymer matrix to lower chain hydrocarbons and fuel gas leaving behind fibres. Mechanical tests of BMC panels, reinforced concrete and compression moulded panels made with recovered fibres were carried out. 10 refs. USA... 

Consolidation and development of interlaminar bond strength for thermoplastic matrix composites have been modeled by two mechanisms intimate contact and autohesion. Intimate contact describes the process by which two irregular ply surfaces become smooth (Fig. 13.10). In areas in which the ply surfaces are in contact, autohesion occurs, and the long thermoplastic polymer chains diffuse across the ply boundaries. Filament winding with thermoplastic matrix materials is considered an on-line consolidation process in that local... 

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