Characterization of poly(lactic acid) biocomposites filled with chestnut shell waste
J Mater Cycles Waste Manag (2018) 20:914–924
https://doi.org/10.1007/s10163-017-0658-5
ORIGINAL ARTICLE
Characterization of poly(lactic acid) biocomposites filled
with chestnut shell waste
M. Barczewski1 · D. Matykiewicz1 · A. Krygier1 · J. Andrzejewski1 · K. Skórczewska2
Received: 1 September 2016 / Accepted: 1 August 2017 / Published online: 11 August 2017
© The Author(s) 2017. This article is an open access publication
Abstract The aim of this study was to determine thermal
and mechanical properties and applicability of ground chestnut shell waste as a filler for poly(lactic acid) composites.
The used amount of filler was ranging from 2.5 to 30 wt%.
Spectroscopic analysis of composites and its ingredients was
conducted by means of FT-IR method. The mechanical and
thermal properties of the composites were determined in
the course of static tensile test, Dynstat impact strength test,
DMTA analysis, and DSC method. The fractured surface
morphology of biocomposites was evaluated by SEM analysis. Incorporation of the filler influenced the overall mechanical properties of the composites characterized by high stiffness and lowered impact resistance. Fabricated composites
with different amounts of non-reactive natural waste filler
exhibited acceptable mechanical and thermal properties.
Therefore, these composites can be used as eco-friendly,
biodegradable materials for low-demanding applications.
Keywords Poly(lactic acid) · Natural composites ·
Mechanical properties · Structure
Introduction
Increasing impact of the plastic products on the development of human life standard is connected with a long-term
* M. Barczewski
1
Polymer Processing Division, Institute of Materials
Technology, Poznan University of Technology, Piotrowo 3,
61‑138 Poznan, Poland
2
Faculty of Chemical Technology and Engineering,
University of Science and Technology in Bydgoszcz,
Seminaryjna 3, 85‑326 Bydgoszcz, Poland
13
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expansion of petroleum-based polymers. Despite trials of the
reducing polymeric waste and strong restrictions concerning
storage and product end-life cycle performance, the amount
of the non-degradable polymer gradually has become ballast
for the environment. Therefore, the endeavor of introducing biodegradable polymers in industrial-scale production
gained ground among scientists [1]. The area of biodegradable material application is continuously extending thanks
to their improving properties which in many cases resemble
petrochemical polymers. In spite of many studies concerning the usage of biodegradable polymers, such as poly(lactic
acid) (PLA) [2–10], poly(butylene adipate-co-terephthalate
(PBAT) [11–13], polypropylene carbonate (PPC) [14–16],
and starch [17–20], their commercial application is still
not very common. Packaging industry appears as a branch
which due to relatively low expectations towards mechanical
properties allows for wide application of fully biodegradable
polymers on a bigger scale [5]. The low thermo-mechanical
stability of green composites, next to relatively high price,
became their biggest disadvantage in comparison to petroleum-based non-biodegradable polymers [5, 13]. Therefore,
it is well founded to use recycled thermoplastic biodegradable polymers as a matrix for composites filled with organic
and inorganic fillers [7, 11].
Except for the application of the specially prepared fiberlike natural fillers (e.g., bamboo, kenaf, jute and flax), great
attention is placed on incorporation of agricultural waste
materials into polymeric matrix [2, 21–25]. Extensive studies showed that presence of the natural fillers in biodegradable polymers may strongly accelerate biodegradation process thanks to faster hydrolysis followed by oxidation of
both biopolymer, as well as the filler. Moreover, presence
of natural filler increases water absorption, which highly
influences biodegradation process of the composites, in
comparison to neat polymer. In case of natural composites
J Mater Cycles Waste Manag (2018) 20:914–924
based on non-degradable polymers, hydrolysis under normal
environment conditions will be reduced only to the particles of the natural filler; hence, polymer matrix becomes
only physically fragmented and eroded [25]. The application of the chestnut shell waste as a natural filler for polymer composites had been previously reported. Kaymakci
et al. investigated the effect of chestnut shell on mechanical properties, as well as dimensional stability of the polypropylene based on composites with application of maleic
anhydride–polypropylene (MAPP) as a coupling agent. The
results presented in their study showed that the incorporation of MAPP into natural composites based on hydrophobic polymeric matrix strongly reduces water absorption and
increases mechanical properties of the modified composites
[26]. Another study which presents the application of chestnut shell waste as a filler was presented by Wu et al., who
focused on the development on poly(butylene succinate)based biocomposites [27]. It should be noticed that no literature studies concerning the modification of the poly(lactic
acid) by chestnut shell powder were presented in the literature. Therefore, the aim of this study is to determine thermal
and mechanical properties of poly(lactic acid) filled with
chestnut shell powder waste composites and potential applications resulting from them.
Experimental
Materials and sample preparation
The commercial injection molding grade poly(lactic acid)
(PLA) Ingeo™ 3001D with a melt flow rate (MFR) of
22 g/10 min (210 °C, 2.16 kg) supplied by Nature Works
(USA) was used in our experiments.
Preliminary preparation of the chestnut shell waste filler
(CN, Aesculus hippocastanum L.) included rinsing in running distilled water and drying at 50 °C for 24 h. First disintegration was processed in a low-speed mill cutter Shini
SC-1411 and then milled in high-speed mill Retsch GM 200
(n = 2000 rpm). Application of the two-step milling allows
the preparation of non-degraded natural filler for PLA-based
biocomposites. The obtained waste chestnut shell powder
was sieved by vibratory sieve shaker ANALYSETTE 3 Pro
equipped with 200-µm-mesh size sieve. Characterization of
particle size distribution was evaluated using laser particle
sizer Fritsch ANALYSETTE 22 apparatus operated in the
range of 0.08–2000 µm.
PLA pellets and CN powder were premixed using
a high-speed rotary mixer Retsch GM200 (t = 3 min,
n = 1000 rpm) with different amounts of filler (2.5, 5, 10,
20, and 30 wt%). Next, all blends were mixed in a molten
state using a ZAMAK 16/40 EDH twin screw co-rotating
extruder that operated at 190 °C and 100 rpm, and pelletized
915
after cooling in a water bath. The normalized specimens
for tensile and impact strength test were prepared with a
Engel HS 80/20 HLS injection molding machine operated
at 190 °C. Injection molding process was realized with the
following parameters: mold temperature Tmould = 25 °C,
injection speed V = 70 mm/s, formin (...truncated)
