CARLOS Domínguez

Carlos Domínguez is Bachelor of Science (Physics) and PhD at the Rey Juan Carlos University, being also Master in High International Studies, Quality and Environmental Management and Advanced Specialization in Plastics and Rubber. He began his professional career in the Institute for the Structure of Matter which belongs to the Spanish National Research Council (CSIC), Department of Macromolecular Physics as responsible for the polymer characterization laboratory in collaboration with Repsol company. Since 2004 he works at the Rey Juan Carlos University, Department of Chemical and Environmental Technology, being the Polymer Technology Laboratory (LATEP) Manager. LATEP (www.latep.es) is a laboratory for the physico-chemical characterization of polymers and the study of their relationship with the molecular structure of the material. The LATEP brings service and support to the research, development and innovation activities of companies and research centers around the world. During the last years Carlos Domínguez has participated in different research projects in polymer science, being specialized in polyolefins characterization, failure mechanisms in polyethylene for pipe applications and polymer recycling and Circular Economy on plastics. Carlos Domínguez is co-author of more than 50 works between publications in high-impact scientific journals and international conferences presentation.

ABSTRACT

ID13

LONG-TERM PERFORMANCE IN PE100 AND PE100RC RESINS: DOES THE COMONOMER LENGTH MATTER?

Carlos Domínguez- LATEP. Rey Juan Carlos University, Spain

Predrag Micic- QENOS Pty Ltd., Australia

Rafael Juan - Rey Juan Carlos University, Spain

Nuria Robledo- Rey Juan Carlos University, Spain

Rafael A. García-Muñoz - Rey Juan Carlos University, Spain

ABSTRACT

Slow Crack Growth (SCG) resistance is the most critical mechanical property that must be controlled and evaluated for determining the long-term performance of polyethylene (PE) pipes. Last generation of bimodal and multimodal ethylene-α-olefin copolymers with exceptional balance of mechanical properties and processability have been developed in the last years. The inclusion of branched chains, preferentially in the high molecular weight region, has been crucial to favor the entanglements and tie molecules formation¹, which are the responsible for inhibiting the crazing phenomena that precedes the crack formation and subsequent SCG process^2,3.

The outstanding SCG resistance of the last generation PE100RC resins has led to the development of new and faster testing methodologies capable of assessing the pipe long-term performance. Accordingly, the latest revision of the standard EN1555 for pipes of gaseous fuels already includes these tests: Strain Hardening (SH) test, Crack Round Bar (CRB) test, Accelerated Full Notch Creep Test (AFNCT) and Accelerated Notch Pipe Test (ANPT). α-olefin comonomers like C4 (1-butene), C5 (1-pentene) and C6 (1-hexene) are some of the most used in the plastic pipes industry. Although the influence of the size of the side chain on properties as SH has been pointed out by some authors^4,5, it is difficult to separate this influence from others as relevant as the length of the main chain and the molecular weight distribution.

In the present work, different PE100 and PE100RC resins have been evaluated following the different standards for measuring the SCG performance. All pipe grades investigated in this work have been commercial products with long history of use in pipes for pressure applications. Interestingly, the resins have almost the same average molecular weight and molecular weight distribution, but different comonomer type: C4, C5 and C6, which permitted the evaluation of the influence of the short chain branching length on SCG phenomena.

1. R. Seguela. Journal of Polymer Science. Part B: Polymer Physics 43 (2005) 1729-1748.

2. R.A.C. Deblieck, D.J.M. van Beek, K. Remerie, I. M. Ward. Polymer 52 (2011) 2979-2990.

3. R.K. Krishnaswamy, Q. Yang, L. Fernandez-Ballester, J. A. Kornfield. Macromolecules 41 (2008) 1693-1704.

4. S. Deveci, S.K. Kaliappan, J. Fawaz, U. Gadgoli, B. Das. Polymer Testing 72 (2018) 285–297.

5. C. Domínguez, N. Robledo, B. Paredes, R. A. García Muñoz. Polymer Testing 81 (2020) 106155.

KEYWORDS:

Slow Crack Growth (SCG), PE100RC, comonomer influence, Strain Hardening (SH) test, Cracked Round Bar (CRB) Test, Accelerated Full Notch Creep Test (AFNCT), Accelerated Notch Pipe Test (ANPT).

The authors kindly acknowledge the technical staff of Polymer Technology Laboratory (LATEP) for their great work and QENOS Pty Ltd for providing the materials and technical support for this research.