PMID- 32993078
OWN - NLM
STAT- PubMed-not-MEDLINE
LR  - 20201101
IS  - 2073-4360 (Electronic)
IS  - 2073-4360 (Linking)
VI  - 12
IP  - 10
DP  - 2020 Sep 26
TI  - Microbuckling Instability and the Second Yield during the Deformation of 
      Semicrystalline Polyethylene.
LID - 10.3390/polym12102208 [doi]
LID - 2208
AB  - Deformation instabilities, such as microbuckling or lamellar fragmentation due to 
      slip localization, play a very important role in the deformation of 
      semicrystalline polymers, although it still not well explored. Such instabilities 
      often appear necessary to modify the deformation path and facilitate strain 
      accommodation in an energy-minimizing manner. In this work, microbuckling 
      instability was investigated using partially oriented, injection-molded (IM) 
      samples of high-density polyethylene, deformed by a plane-strain compression. 
      Deformed samples were probed by SEM, X-ray (small- and wide-angle X-ray 
      scattering: SAXS, WAXS), and differential scanning calorimetry (DSC). It was 
      found that microbuckling instability, followed quickly by the formation of 
      lamellar kinks, occurred in high-density polyethylene (HDPE) at a true strain of 
      about e = 0.3-0.4, mainly in those lamellar stacks which were initially oriented 
      parallel to the compression direction. This phenomenon was observed with scanning 
      electron microscopy, especially in the oriented skin layers of IM specimens, 
      where a chevron morphology resulting from lamellae microbuckling/kinking was 
      evidenced. Macroscopically, this instability manifested as the so-called "second 
      macroscopic yield" in the form of a hump in the true stress-true strain curve. 
      Microbuckling instability can have a profound effect on the subsequent stages of 
      the deformation process, as well as the resulting structure. This is particularly 
      important in deforming well-oriented lamellar structures-e.g., in drawing 
      pre-oriented films of a semicrystalline polymer, a process commonly used in many 
      technologies.
FAU - Bartczak, Zbigniew
AU  - Bartczak Z
AUID- ORCID: 0000-0003-0514-9106
AD  - Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, 
      Sienkiewicza 112, 90-363 Lodz, Poland.
FAU - Vozniak, Alina
AU  - Vozniak A
AD  - Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, 
      Sienkiewicza 112, 90-363 Lodz, Poland.
LA  - eng
GR  - DEC-2014/15/B/ST8/04306/Narodowe Centrum Nauki/
PT  - Journal Article
DEP - 20200926
PL  - Switzerland
TA  - Polymers (Basel)
JT  - Polymers
JID - 101545357
PMC - PMC7599652
OTO - NOTNLM
OT  - deformation instabilities
OT  - deformation mechanisms
OT  - kinks
OT  - lamellae buckling
OT  - polyethylene
OT  - semicrystalline polymer
COIS- The authors declare no conflict of interest. The funders had no role in the 
      design of the study; in the collection, analysis, or interpretation of data; in 
      the writing of the manuscript; or in the decision to publish the results.
EDAT- 2020/10/01 06:00
MHDA- 2020/10/01 06:01
PMCR- 2020/09/26
CRDT- 2020/09/30 01:02
PHST- 2020/09/04 00:00 [received]
PHST- 2020/09/22 00:00 [revised]
PHST- 2020/09/24 00:00 [accepted]
PHST- 2020/09/30 01:02 [entrez]
PHST- 2020/10/01 06:00 [pubmed]
PHST- 2020/10/01 06:01 [medline]
PHST- 2020/09/26 00:00 [pmc-release]
AID - polym12102208 [pii]
AID - polymers-12-02208 [pii]
AID - 10.3390/polym12102208 [doi]
PST - epublish
SO  - Polymers (Basel). 2020 Sep 26;12(10):2208. doi: 10.3390/polym12102208.