Poly impact fracture surfaces

The removal of direct carbon replicas is dependent upon the polymer. Boiling xylene vapor was used to remove drawn PE from replicas [296] in work on drawn polymer morphology. Hobbs and Pratt [297] described a direct carbon replica method for replication of a PBT impact fracture surface by evaporation of platinum at 20° and PBT removal in hexafluor-oisopropanol (HFIP). Latex film coalescence in poly(vinyl acrylate) homopolymer and vinyl acrylic copolymer latexes was studied using direct replicas [298]. As the latex films have a low glass transition temperature, they were cooled by liquid nitrogen to about -150°C in the vacuum evaporator and shadowed with Pt/ Pd at 45° followed by deposition of a carbon support film at 90° to the specimen surface. The latex films were dissolved in methyl acetate/ methanol. TEM micrographs of the latex films show the difference between films aged for various times (Section 5.5.2). 

Most unusual and initially most surprising was the amount of plastic strain measured in impacted RDX crystals. RDX is usually regarded as a brittle crystal which fractures at about 10 % strain. Impact on 50 to 100 mg of poly-crystalline RDX samples by a 10 kg free falling drop weight released from a height of about. 2 m formed disc shaped samples about 15 mm in diameter and. 1 mm thick. The surfaces of the impactor and the anvil on which the sample was placed were... 

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