Polyethylene terephthalate fracture

Fig. 6.8. Fracture toughness, K, of short glass fiber-thermoplastics injection molded composites as a function of weight fraction of fiber, fVr. (O) and (A) polyethylene terephthalate (PET) matrix ( ) and (A) polycarbonate (PC) matrix. Notches made transverse (O, ) and parallel (A, A) to the mold fill direction,...

Friedrich, K. Microstructure and Fracture of Fiber Reinforced Thermoplastic Polyethylene Terephthalate, Center for Composite Materials, University of Delaware, U.S.A., Report No. CCM-80-17, 1980... 

Toughness, modifier, polyethylene terephthalate, core-shell, essential work of fracture... 

The postyield ductile fracture of polymers was extensively investigated (170-183), resulting in a conclusion that the crack is initiated from cavities growing from defects in the drawn material. These cavities have a rhombic shape with the long and short diagonals perpendicular and parallel to the draw direction. These cavities were observed in PVC, PE, polyethylene terephthalate (PET) at room temperature and in PC, PMMA, polyether sulfone (PES), and PS at elevated temperatures. At slow strain rates, the growth of these cavities in a plastically deformed material loaded in tension is stable until the critical size is reached resulting in an unstable catastrophic failure. 

Janik and Krolikowski [53] investigated the effect of Charpy notched impact strength and other mechanical properties such as tensile strength, flexural strength, elastic modulus, flexural modulus, melt viscosity, and fracture on the mechanical and rheological properties of PE-polyethylene terephthalate (PET) blends. 

P. I. Vincent, S. Picknell, G. F. Harding An Investigation of Fracture Criteria for Anisotropic Polyethylene Terephthalate Film Using Mechanical and Optical Techniques, Div. Pol. Sci. Case Western Reserve Univ., Cleveland, Ohio 44106 (1967). 

Kolbeck and Uhlmann have considered the effect of high stress extrusion on the properties of several polymers - polypropylene, poly(vinylidene fluoride) and polyethylene. There was no substantial heating on deformation up to twenty-five times. Polypropylene and poly(vinylidene fluoride) could not be continuously extruded below the melting point and brittle fracture and necking was observed, while the tensile properties depend on draw ratio with yielding. Above 373 K annealing occurs but the product has a lower elongation to break. The properties of oriented nylon-6, > polyfethylene terephthalate)," - polypropylene, and polyethylene " have been widely studied. 

Several workers have proposed new combinations of materials in an attempt to overcome wear. Studies involving polyimides, polyamide-imides, and poly-tetrafluoroethylene-filled polyoxymethylene demonstrated that although wear characteristics were good in dry conditions, the presence of lubricants (blood plasma, water) decreased the wear resistance. Results obtained with reinforcing materials such as carbon fibre and with an aluminium oxide ceramic ball used in conjunction with a polyethylene socket have been presented, Examples of other types of reconstructive surgery involving hard tissue replacement are the use of poly(methyl methacrylate) in chest wall reconstruction and repair of depressed skull fractures, the repair of major crano-orbital defects with the aid of a polyurethane-coated poly(ethylene terephthalate) mesh, and the use of silicone rubber in total finger joint and carpal bone replacement. 

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