Thermoplastic material surfaces

Thermoplastics. There are five elastomeric membranes that are thermoplastic. Two materials, chlorinated polyethylene (CPE) and polyisobutylene (PIB), are relatively obscure. Thermoplastic materials can be either heat-fused or solvent-welded. In contrast to Hypalon and uncured EPDM, this abiHty to fuse the membranes together remains throughout the life of the material. However, cleaning of the membrane surface after exposure to weather is required. Correct cleaning procedures for specific membranes are available from the individual manufacturer. 

The use of a special ebonite as the thermoplastic material in the printing process of electro typing, a method of producing metal replicas of printing surfaces. 

The curve of the apparent viscosity data versus temperature for PP/PU/APP is reported in the Figure 10.9. In the first step (200°C-240°C), the viscosity of the material decreases when the temperature increases following the behavior of a thermoplastic material. Even though we observe in this step a carbonization of the material surface, the polymeric matrix has been preserved under the surface. In the 240°C-300°C temperature range, the viscosity value slightly decreases and its value remains close to the low apparent viscosity of the material molten at 240°C. The sample appears as completely carbonized and liquid. The plateau may then be explained by the chemical transformation of the material (formation of phosphoric acid esters and aromatic species).33... 

Thermoplastic materials often have a lower surface energy than do thermosetting materials. Thus, physical or chemical modification of the surface is necessary to achieve acceptable bonding. This is especially true of the crystalline thermoplastics such as polyolefins, linear polyesters, and fluoropolymers. Methods used to increase the surface energy and improve wettability and adhesion include... 

In a thermoplastic material it is, therefore, important to distinguish between the crack opening stretch (= COS) and the maximum craze width 2v. To characterize plastic deformation and fracture behavior of a thermoplastic material the maximum length of stretched fibrils and hence the maximum craze width 2v is a more fundamental parameter than the crack opening stretch. The latter, in addition, depends on the relaxation behavior of the broken remnants on the fracture surface. 

Performance requirements for other large plastic parts like fascia, hoods, and deck Hds would most likely eliminate one or another of these polymers and/or molding processes from consideration. For example, SMC 1s not considered to have sufficient Impact resistance for fascia and RIM and engineering thermoplastic materials have yet to be developed for structural applications which also require a high surface quality, 1.e. hoods and deck lids. These other parts were thus not chosen for this study. 

Behavior at higher temperatures This test is easily carried out by contact with a hot soldering rod. On thermoset material, the surfaces remain unchanged, on thermoplastic material a plastification, respectively, melting can be observed. 

Coextrusion produces a multi-ply material directly from the individual resins. The method is limited to thermoplastic materials such as polythene, polypropylene and nylons. Thin layers of extruded bonding resins are necessary to combine many of the resins. Coextrudates have to be surface printed and the outer film cannot be reverse printed as it is often used with more conventional laminates with a film outer ply. 

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