On the Determination of Fracture Toughness of PP Polymers

ALICIA SALAZAR; L.A. FASCE,; J. RODRÍGUEZ; P. M. FRONTINI

Ottawa

Conferencia; 12 th. International Conference of Fracture; 2009

<!-- /* Font Definitions */ @font-face {font-family:Batang; panose-1:2 3 6 0 0 1 1 1 1 1; mso-font-alt:바탕; mso-font-charset:129; mso-generic-font-family:auto; mso-font-format:other; mso-font-pitch:fixed; mso-font-signature:1 151388160 16 0 524288 0;} @font-face {font-family:TimesNewRomanPSMT; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:0; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:auto; mso-font-signature:3 0 0 0 1 0;} @font-face {font-family:"@Batang"; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:129; mso-generic-font-family:auto; mso-font-format:other; mso-font-pitch:fixed; mso-font-signature:1 151388160 16 0 524288 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-fareast-language:ES;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} /* List Definitions */ @list l0 {mso-list-id:114250738; mso-list-type:hybrid; mso-list-template-ids:1615109932 446981014 201981977 201981979 201981967 201981977 201981979 201981967 201981977 201981979;} @list l0:level1 {mso-level-tab-stop:36.0pt; mso-level-number-position:left; text-indent:-18.0pt;} @list l0:level2 {mso-level-number-format:alpha-lower; mso-level-tab-stop:72.0pt; mso-level-number-position:left; text-indent:-18.0pt;} @list l0:level3 {mso-level-number-format:roman-lower; mso-level-tab-stop:108.0pt; mso-level-number-position:right; text-indent:-9.0pt;} @list l0:level4 {mso-level-tab-stop:144.0pt; mso-level-number-position:left; text-indent:-18.0pt;} @list l0:level5 {mso-level-number-format:alpha-lower; mso-level-tab-stop:180.0pt; mso-level-number-position:left; text-indent:-18.0pt;} @list l0:level6 {mso-level-number-format:roman-lower; mso-level-tab-stop:216.0pt; mso-level-number-position:right; text-indent:-9.0pt;} @list l0:level7 {mso-level-tab-stop:252.0pt; mso-level-number-position:left; text-indent:-18.0pt;} @list l0:level8 {mso-level-number-format:alpha-lower; mso-level-tab-stop:288.0pt; mso-level-number-position:left; text-indent:-18.0pt;} @list l0:level9 {mso-level-number-format:roman-lower; mso-level-tab-stop:324.0pt; mso-level-number-position:right; text-indent:-9.0pt;} ol {margin-bottom:0cm;} ul {margin-bottom:0cm;} --> The fracture behavior of Polypropylene polymers is rather controversial since isneither completely brittle nor entirely ductile. Scatter in toughness results anddifficulty in distinguishing the amount of stable crack growth impair the situation.Consequently, conventional methods based exclusively either on linear elasticfracture mechanics theory (LEFM) or on non-linear elastic fracture mechanicstheory (NLEFM) are not suitable. It was demonstrated by Cocco et al in 2005,that Weibull statistical method could be successfully used to determine thetoughness of polymers displaying ductile-to-brittle behavior. On the other side,when the amount of stable crack growth was not easy to distinguish on fracturesurface, it was also argued in literature that a Jc value may be determined usingthe stress whitening method suggested by Zhang et al in 1989.The present study compares the PP toughness values determined by the statisticalapproach and the stress whitening method. It also discusses the reliability of bothvalues and the advantages and drawbacks of each methodology.