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academies
July 23-25, 2018 | Moscow, Russia
Materials Science and Engineering
International Conference on
Journal of Materials Science and Nanotechnology | Volume 2
B
iodegradable plastics are the subject of substantial
changes of properties due to degradation initiated by
enzymes produced by various bacteria. Before obvious changes
are observed visually, modification of physical properties
is important, occurring in the stage when the material is
apparently
unchanged.Weinvestigateddegradation in compost
of virgin polylactic acid (PLA), PLA with a plasticizer triacetin
(TAC), and a mixture of PLA / polyhydroxy butyrate (PHB) with
TAC. Degradation proceeded at 58
o
C up to 16 days and physical
properties were measured. The degradation rate varied a little
for the three samples. For virgin PLA the degradation test was
performedalsoat 25and37
o
C. Biodegradationwas substantially
slower compared to 58
o
C, but hardly any difference was
observed between 25 and 37
o
C. Obviously, the key factor for
the degradation rate is glass transition temperature of PLA,
being around 55
o
C. Physical properties were measured for 8
days (testing specimens keeping their shape intact) or in some
cases up to 16 days. At longer periods the materials have been
disintegrated to too small fragments to perform any analysis.
Complex design of testing methods involved molecular weight
and molecular weight distribution made by GPC, supported by
measuring measurement of viscosity by rheology. Changes in
structure of the materials were determined from changes in
Tg and crystallinity determined by DSC. Mechanical properties
of samples after certain time of composting were measured
and the data were compared with information obtained
from dynamic mechanical analysis (DMTA), which provided
also exact data on changes in glass transition temperature.
From the courses of alterations of various parameters the
conclusions have been made regarding the effect of TAC and
PHB presence on the biodegradation of PLA, and related
changes concerning the structure / mechanical relations.
Acknowledgement: VEGA 2/0019/18, VEGA 1/0570/17, APVV
15-0741
Speaker Biography
Chodak Ivan is a senior scientist at Polymer Institute SAS in Bratislava, Slovakia. His
scientific interests cover crosslinking of polyolefins (patented extremely efficient
system for polypropylene crosslinking), multiphase systems, i.e. polymer blends and
composites with polymeric matrices including nanocomposites and electroconductive
composites. Investigation of biodegradable polymers belongs to his most successful
topics (patented material based on PHB and PLA with very high toughness, the
commercial production is under preparation). He is the author of over 150 scientific
publications, 15 patents (4 of them applied in industry). Frequent and long-term
cooperation with industry (DSM, BASF, Biomer, National Power, GE Plastics etc.).
e:
upolchiv@savba.skChodak Ivan
Polymer Institute of the Slovak Academy of Sciences, Slovakia
Effect of Biodegradation on physical properties of PLA- based blends