ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract By the radiolysis of poly(methylmethacrylate) (PMMA), the fracture surface energy (γ) was determined at room temperature as a function of viscosity average molecular weight (¯M v). Using a modified parallel cleavage technique, results showed that γ decreased more than two orders of magnitude with decreasing molecular weight. In the high molecular weight region (¯M v≳105), γ (∼1×105 erg cm−2) was relatively insensitive to polymer chain length; whereas for 2.5×104≲¯M v≲ 1×105, γ was strongly dependent on molecular weight. A linear regression analysis in the range ¯M v=2 to 2.25×103 indicated that a truly glassy “Griffith” material was approached for which γ ≃ 750 erg cm−2. The results confirm the sigmoidal dependence of γ on molecular weight tested in notched tension. The apparent independence which variations in crack velocity have on γ with decreasing ¯M v is shown and explained in terms of the increasingly brittle character of PMMA. Problems associated with the measurement and interpretation of experimental data are considered, particularly with respect to the lower ¯M v regions.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00540881
