scholarly journals Macromolecular Insights into the Altered Mechanical Deformation Mechanisms of Non-Polyolefin Contaminated Polyolefins

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 239
Author(s):  
Ruben Demets ◽  
Marie Grodent ◽  
Karen Van Van Kets ◽  
Steven De De Meester ◽  
Kim Ragaert
Keyword(s):  
Interfacial Adhesion ◽  
Tensile Deformation ◽  
Linear Structure ◽  
Polyamide 6 ◽  
Deformation Mechanisms ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Pure Material ◽  
Polymer Type

Current recycling technologies rarely achieve 100% pure plastic fractions from a single polymer type. Often, sorted bales marked as containing a single polymer type in fact contain small amounts of other polymers as contaminants. Inevitably, this will affect the properties of the recycled plastic. This work focuses on understanding the changes in tensile deformation mechanism and the related mechanical properties of the four dominant types of polyolefin (PO) (linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP)), contaminated with three different non-polyolefin (NPO) polymers (polyamide-6 (PA-6), polyethylene terephthalate (PET), and polystyrene (PS)). Under the locally elevated stress state induced by the NPO phase, the weak interfacial adhesion typically provokes decohesion. The resulting microvoids, in turn, initiate shear yielding of the PO matrix. LLDPE, due to the linear structure and intercrystalline links, is well able to maintain high ductility when contaminated. LDPE shows deformation similar to the pure material, but with decreasing ductility as the amount of NPO increases. Addition of 20 wt% PA-6, PET, and PS causes a drop in strain at break of 79%, 63%, and 84%, respectively. The typical ductile necking of the high-crystalline HDPE and PP is strongly disturbed by the NPO phase, with a transition even to full brittle failure at high NPO concentration.

scholarly journals Microstructural Contributions of Different Polyolefins to the Deformation Mechanisms of Their Binary Blends

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1171 ◽  
Author(s):  
Astrid Van Belle ◽  
Ruben Demets ◽  
Nicolas Mys ◽  
Karen Van Kets ◽  
Jo Dewulf ◽  
...  
Keyword(s):  
Polymer Blends ◽  
Tensile Deformation ◽  
Deformation Mechanisms ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Mechanical Recycling ◽  
Immiscible Polymer Blends ◽  
Binary Blends ◽  
Brittle Behavior ◽  
Clear Cut

The mixing of polymers, even structurally similar polyolefins, inevitably leads to blend systems with a phase-separated morphology. Fundamentally understanding the changes in mechanical properties and occurring deformation mechanisms of these immiscible polymer blends, is important with respect to potential mechanical recycling. This work focuses on the behavior of binary blends of linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP) under tensile deformation and their related changes in crystallinity and morphology. All of these polymers plastically deform by shear yielding. When unmixed, the high crystalline polyolefins HDPE and PP both exhibit a progressive necking phenomenon. LDPE initiates a local neck before material failure, while LLDPE is characterized by a uniform deformation as well as clear strain hardening. LLDPE/LDPE and LLDPE/PP combinations both exhibit a clear-cut matrix switchover. Polymer blends LLDPE/LDPE, LDPE/HDPE, and LDPE/PP show transition forms with features of composing materials. Combining PP in an HDPE matrix causes a radical switch to brittle behavior.

In Situ Positron Lifetime Measurement for the Strained Polyethylene

2012 ◽  
Vol 733 ◽  
pp. 139-142
Author(s):  
Masanori Fujinami ◽  
Ryutaro Minei ◽  
Chang Gui Liu ◽  
Kenta Hara
Keyword(s):  
Structural Change ◽  
Positron Lifetime ◽  
Tensile Deformation ◽  
Positron Annihilation Spectroscopy ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Day By Day ◽  
Positron Lifetime Measurement

The in situ positron annihilation spectroscopy measurement has been developed and applied to investigate the structural change in free volume on the tensile deformation of linear low-density polyethylene. The pick-off lifetime of ortho-positronium (Ps) decreases by applying the strain and an aging variation cannot be observed. On the contrary the fraction of Ps formation gradually decreases day by day and becomes constant after several days. Further, after release of strain, it returns to the original value. The reason is considered to be that the molecular chains become rigid gradually during deformation and they lose the flexibility.

Development of antistatic packaging of polyamide 6/linear low-density polyethylene blends-based carbon black composites

2019 ◽  
Vol 77 (7) ◽  
pp. 3389-3409 ◽  
Author(s):  
Leonardo Nishiguti Silva ◽  
Erick Gabriel Ribeiro dos Anjos ◽  
Guilherme Ferreira de Melo Morgado ◽  
Juliano Marini ◽  
Eduardo Henrique Backes ◽  
...  
Keyword(s):  
Carbon Black ◽  
Polyamide 6 ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Polyethylene Blends

The Effect of Fiber Surface Treatment on the Water Absorption and Morphological Properties of Linear Low Density Polyethylene/Poly(Vinyl Alcohol)/Kenaf Composites

2017 ◽  
Vol 264 ◽  
pp. 1-4
Author(s):  
Ai Ling Pang ◽  
Hanafi Ismail ◽  
Azhar Abu Bakar
Keyword(s):  
Sodium Bicarbonate ◽  
Water Absorption ◽  
Vinyl Alcohol ◽  
Interfacial Adhesion ◽  
Morphological Properties ◽  
Low Density Polyethylene ◽  
Poly Vinyl Alcohol ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Chromium Sulfate

The effect of untreated and treated (chromium sulfate and sodium bicarbonate) kenaf (KNF) on the water uptake and morphological properties of linear low density polyethylene/poly(vinyl alcohol)/kenaf (LLDPE/PVOH/KNF) composites was studied. The composites were prepared by using an internal mixer (Haake Polydrive) at 150 °C and 50 rpm for 10 min. The results showed that the untreated composites tend to absorb greater amount of water compared to the treated composites. This shows that the chromium sulfate and sodium bicarbonate treatment on KNF had improved the interfacial adhesion between KNF and LLDPE/PVOH matrices. Consequently, the capability of water absorption by the treated composites was reduced. Scanning electron microscope (SEM) result shows that lesser traces of filler pull-out and better filler-matrix interfacial adhesion were observed in the tensile fractured surfaces of treated composites.

scholarly journals Microstructural Origin of the Double Yield Points of the Metallocene Linear Low-Density Polyethylene (mLLDPE) Precursor Film under Uniaxial Tensile Deformation

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 126
Author(s):  
Obaid Iqbal ◽  
Jean Claude Habumugisha ◽  
Shengyao Feng ◽  
Yuanfei Lin ◽  
Wei Chen ◽  
...  
Keyword(s):  
Yield Point ◽  
High Performance ◽  
Monoclinic Phase ◽  
Tensile Deformation ◽  
Low Density Polyethylene ◽  
Uniaxial Tensile ◽  
Precursor Film ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Double Yield

The microstructural origin of the double yield points of metallocene linear low-density polyethylene (mLLDPE) precursor films has been studied with the assistance of the synchrotron radiation small- and wide-angle X-ray scattering (SAXS/WAXS). It has been shown that the microstructural origin of the double yield points is highly related to the initial orientation of the original precursor film. For less oriented mLLDPE precursor films, the rearrangement of lamellae and the appearance of the monoclinic phase are the microstructural origins of the first yield point. In comparison, for the highly-oriented mLLDPE precursor film, only the orthorhombic-monoclinic phase transition appears at the first yield point. The melting-recrystallization and the formation of the fibrillary structure happen beyond the second yield point for all studied mLLDPE precursor films. Finally, the detailed microstructural evolution roadmaps of mLLDPE precursor films under uniaxial tensile deformation have been established, which might serve as a guide for processing high-performance polymer films by post-stretching.

scholarly journals Identification of the LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1537
Author(s):  
Luděk Hynčík ◽  
Petra Kochová ◽  
Jan Špička ◽  
Tomasz Bońkowski ◽  
Robert Cimrman ◽  
...  
Keyword(s):  
Strain Rate ◽  
Material Model ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Stress Strain ◽  
Rate Dependent ◽  
Constitutive Material Model ◽  
Principal Directions ◽  
Constitutive Material

Current industrial trends bring new challenges in energy absorbing systems. Polymer materials as the traditional packaging materials seem to be promising due to their low weight, structure, and production price. Based on the review, the linear low-density polyethylene (LLDPE) material was identified as the most promising material for absorbing impact energy. The current paper addresses the identification of the material parameters and the development of a constitutive material model to be used in future designs by virtual prototyping. The paper deals with the experimental measurement of the stress-strain relations of linear low-density polyethylene under static and dynamic loading. The quasi-static measurement was realized in two perpendicular principal directions and was supplemented by a test measurement in the 45° direction, i.e., exactly between the principal directions. The quasi-static stress-strain curves were analyzed as an initial step for dynamic strain rate-dependent material behavior. The dynamic response was tested in a drop tower using a spherical impactor hitting a flat material multi-layered specimen at two different energy levels. The strain rate-dependent material model was identified by optimizing the static material response obtained in the dynamic experiments. The material model was validated by the virtual reconstruction of the experiments and by comparing the numerical results to the experimental ones.

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