CHARACTERIZATION OF POST-USE POLYETHYLENE AND POLYPROPYLENE RECYCLATE BLENDS FOR PIPE APPLICATIONS

Papers # 2018 Las-Vegas

Despite recent efforts in promoting the utilization of recycled polymeric materials for more diverse and more advanced applications, there are still significant knowledge gaps with regards to the applicability of certain recyclate types for specific “re-use” purposes. When it comes to pipe applications, for instance, a considerable body of work exists on recycled polyvinylchloride (rPVC), however, systematic investigations of mechanically recycled polyethylene (rPE) and polypropylene (rPP) for structural performance applications such as pipes are still rare. Especially studies of the resistance against slow crack growth, which is a highly relevant failure mechanism of pressurized plastic pipes, are lacking for rPE and rPP. This is particularly true for blends of rPE and rPP, which are of high practical relevance not at least due to cost advantages over mono-fraction recyclates.

In the present work two rPE and two rPP grades originating from post-use sources such as bottle caps, extrusion blow molded objects and injection molded items were analyzed together with six PE-PP recyclate blends produced from these four base recyclates. The recyclate blends differed in the rPE-to-rPP ratio and the amount of calcium carbonate additive used in the recyclate compounding and blending step. 

Composition and molecular characteristics of both post-use base recyclates and recyclate blends were investigated using Fourier-transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). A subsequent mechanical characterization based on concepts of linear-elastic fracture mechanics was performed using compact-type (CT) specimens to determine the crack growth resistance of the various recyclate materials under cyclic loads. 

Small amounts of legacy substances were detected in both rPE and rPP. In terms of crack growth resistance, clear rankings of the materials were derived, with the recyclate blends being inferior to the neat rPE or rPP materials.

Related keywords : Polyethylene polypropylene blend, mechanical recycling, post-consumer, legacy substances, crack growth resistance.
Please note that the whole article content is available on PPCA website onlySource : 2018 Las-Vegas


Related papers

A RECENT SURVEY OF WATER MAIN FAILURES IN THE US AND CANADA

Author(s) : Steven Folkman 2018 Las-Vegas

A recent survey again confirms that PVC pipe has the lowest break rate when compared with break rates of ductile and cast iron, asbestos cement, steel, and concrete pipe. Other results of interest to water utilities and engineers are discussed. During 2017, Utah State University conducted a survey of utilities across...

EFFECT OF BETA-NUCLEATION ON AGING AND CRACK GROWTH RESISTANCE OF POLYPROPYLENE EXPOSED TO CHLORINATED WATER

Author(s) : Joerg Fischer, Paul J. Freudenthaler, Patrick R. Bradler, Reinhold W. Lang, Susan C. Mantell 2018 Las-Vegas

This research addresses the effect of nucleation on the global aging behavior and the fatigue crack growth (FCG) resistance of commercial alpha- and beta-nucleated polypropylene random copolymer pipe grades (PP-R) when exposed to chlorinated water (5 mg/l free chlorine) at an elevated temperature of 60°C. Comparing...

FATIGUE CRACK GROWTH TESTING IN CHLORINATED WATER AT ELEVATED TEMPERATURES - TEST EQUIPMENT AND TEST PROCEDURE

Author(s) : Joerg Fischer, Patrick R. Bradler, Reinhold W. Lang 2018 Las-Vegas

In the present paper, a novel test system for conducting fatigue crack growth (FCG) experiments under superimposed mechanical-environmental conditions is presented. FCG experiments were performed on a polypropylene (PP) grade and a short-glass fiber reinforced polyamide 66 (PA-GF) grade as model materials. The...

A NOVEL PROCEDURE FOR CHARACTERIZING FATIGUE CRACK GROWTH IN CRB SPECIMENS VIA AN OPTICAL TECHNIQUE

Author(s) : Joerg Fischer, Paul J. Freudenthaler, Patrick R. Bradler, Reinhold W. Lang 2016 Berlin

Cyclic tests with cracked round bar (CRB) specimens have been used for some time to characterize the slow crack growth behavior of polyolefin pipe grade materials. In fact, most recently a standardized test procedure for cyclic CRB testing has been released in ISO 18489. To obtain kinetic data for cyclic crack growth...

A PROPOSED PROCEDURE FOR PVC PIPE TEMPERATURE DE-RATING IN NORTH AMERICA

Author(s) : Steven Folkman, Ron Bishop 2016 Berlin

There are guidelines in AWWA standards for de-rating a PVC pipe’s pressure class if the operating temperature exceeds 23°C. These de-rating factors are appropriate for a system operated at a constant elevated temperature. In the warm desert climates in the USA it is common for the water mains to exceed room...

A SIMPLE DESIGN PROCEDURE FOR PVC PIPE TO ACCOUNT FOR CYCLIC PRESSURE LOADING

Author(s) : Steven Folkman, Ron Bishop 2016 Berlin

One of conditions design engineers face is selecting an appropriate pipe wall thickness (or DR) that will accommodate both maximum operating pressure and repeated surge pressure events. Methods for assessing the number of cycles to failure is quite well developed for PVC pipe. Fracture mechanics approaches can be very...

FATIGUE CRACK GROWTH RESISTANCE OF POLYPROPYLENE IN CHLORINATED WATER AT DIFFERENT TEMPERATURES

Author(s) : Joerg Fischer, Patrick R. Bradler, Reinhold W. Lang, Gernot M. Wallner 2016 Berlin

The present paper aims to study the crack growth resistance of a black-pigmented polypropylene pipe grade when exposed to elevated temperatures and various environmental media (air, deionized water, ionized water with a specific chloride content, and chlorinated water) under the simultaneous application of cyclic...

QUALITY AND PERFORMANCE ASSESSMENT OF IN-PLANT AND POST-USE PE RECYCLATES FOR PIPE APPLICATIONS

Author(s) : Reinhold W. Lang, Patrick R. Bradler, Joerg Fischer, Dominik Poehlmann, Steven Schmidt, Ansgar Niehoff 2016 Berlin

In the present paper, a highly effective test and characterization concept for polymer recyclate materials is proposed and validated. Based on the proposed methods, a study was carried out to investigate the potential of in-plant and post-use PE recyclates from various applications to be utilized in PE recyclate...

THE NEW DIMENSION OF PIPE EXTRUSION

Author(s) : Brigitte Diekhaus, Ralf Mickley, Dr. Henning Stieglitz, Heinrich Dohmann, Dr. Markus Bornemann 2016 Berlin

The paper offers an overview of systems and components for efficient pipe extrusion, particularly for larger and thick-walled pipes. It introduces several possibilities for lower melt temperatures and internal pipe cooling. Together these systems can significantly reduce sagging and cooling length needed in the line....

Application of a Rapid LC-MS Technique to the Development of an Enhanced Chlorine Resistant Antioxidant Package for Polyethylene: Comparison to Oit and Resin Property Retention

Author(s) : Steven Horwatt, Randall Duderstadt, Douglas Keller, Sameer Mehta 2014 Chicago

The development of an antioxidant package for potential use in chlorine resistance of polyethylene pipe is a timeintensive exercise. Previous studies have shown that simple bench top experiments in the solution phase, coupled with LC-MS as a rapid tool for evaluating the analysis of antioxidant reaction products after...

Members of the Association

BOREALISBOROUGEINEOS O&PIRPCKorea Petrochemical IND. Co., LTDLyondellBasellPetroChina Dushanzi Petrochemical CompanyPRIME POLYMERSABICSCG Chemicals & Thai PolyethyleneSinopecTASNEE
TOP