Thermosetting liquid resins

Matrix materials for commercial composites are mainly liquid thermosetting resins such as polyesters, vinyl esters, epoxy resins, and bismaleimide resins. Thermoplastic composites are made from polyamides, polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polysulfone, polyetherim-ide (PEI), and polyamide-imide (PAI). 

CNC MEL DF 50 is a viscous, water clear liquid thermosetting resin which is soluble in water at any concentration. The product is fully compatible with other thermosetting resins, organic and inorganic catalysts, synthetic softeners and also thermoplastic materials. 

In the modification with liquid thermosetting resins, considerable amounts of polymerisable low-molecular weight polymers or prepolymers are added in a liquid form to cement mortar and concrete during mixing. The... 

Resin transfer moulding The disk is moulded directly onto the machined recess on the cathode sheet using a liquid thermosetting resin with silica fiber fillers, as shown in Figure 4. 

Laminates can be defined as combinations of liquid thermosetting resins with reinforcing materials that are bonded together by the application of heat and pressure, forming an infusible matrix. Plywood is a good example of a thermosetting laminate with the phenolic resin... 

Figure F.2 Filament winding process using a liquid thermosetting resin system. (Ref HuU, J.L., Processing of Thermosets , Modern Plastics Handbook, McGraw-HiU, New York, 2000)...

The common feature of all LCM processes is the injection of a liquid thermoset resin into a bed of stationary (or almost stationary) fibrous preform (see Fig. 9.1). Although this chapter is devoted to the RTM process only, we will point out advantages/disadvantages of RTM compared to the other processes also addressed in this book. First, we will describe the RTM process and briefiy introduce other LCM processes in reference to RTM before highlighting the advantages and shortcomings of RTM as compared to the latter mutations of this process. 

The RTM process begins with a dry fiber preform. The preform is placed into a matched metal mold and the mold is closed resulting in the compaction of the preform to the specified fiber volume fraction. A liquid thermosetting resin is then injected into the mold (typically at high pressure, such as 5-7 bar). The mold and resin can be preheated before injection, or the mold can be heated after injection to cure the resin. Due to the high injection pressures and often high temperatures involved, RTM tools are bulky and costly to manufacture and to process. To aid filling of the mold, vacuum may also be applied to remove trapped air. In addition, vacuum can be used to optimize the resin infusion/injection. This leads to VARTM. More information on RTM can be found in Chapters 9-11. 

The RTM process can be spht into four steps as depicted in Fig. 7.1. First a stack of dry reinforcements is assembled into a preform, often formed into the shape of the final part and held together with some form of binder or stitching. This preform is placed into the mould (Fig. 7.1(a)) and the mould is then closed to the desired final cavity thickness (Fig. 7.1(b)). After closing the mould, a liquid thermoset resin is injected into the preform through one or more inlet ports (Fig. 7.1(c)). Resin cute is then initiated and completed either by implementing a thermal cure cycle or by waiting the desired amount of time before demoulding the manufactured part (Fig. 7.1(d)). 

Glass fiber reinforced material (30-45 per cent by volume) and a liquid thermosetting resin are simultaneously formed into a male or female mold and cured at room temperature or with the application of heat to accelerate the process (see 2.8F). 

Cured-in-place A bonded internal repair system using a thin and flexible reinforced textile liner with the outermost layer coated with polyethylene and the inside diameter saturated with liquid thermosetting resin. The liner is usually installed by using water pressure to propel the liner through the pipe and turn it inside out so that the saturated resin side is pressed tightly against the host pipe section to be repaired (Rusch, 2004). 

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