Somayeh Mohammadi, Martin G. Bouldo, Mojtaba Enayati. FeCl3-Doped Cobalt Ferrite as an Efficient Magnetic Catalyst for PET Glycolysis Depolymerization. Journal of Polymers and the Environment 2024 In press (https://doi.org/10.1007/s10924-024-03341-2).
Pixiang Wang, Dayne M. Long, Ke Zhan, Yucheng Peng, Yifen Wang, Shaoyang Liu. Monitoring
CaCO3 Content in Recycled Polypropylene with Raman Spectrometry. ACS Omega 2024, 9, 23462鈥�23467.
Xueqi Wang, Pixiang Wang, Shaoyang Liu, Ke Zhan, Brian Via, Tom Gallagher, Mathew
Smidt, Douglas J. Gardner, Thomas Elder, Yucheng Peng. Identification of percolation
threshold of spray-dried cellulose nanocrystals in homopolymer polypropylene composites.
Journal of Applied Polymer Science 2024, e55627.
Pixiang Wang, Ke Zhan, Xueqi Wang, Yucheng Peng, Haixin Peng, Yifen Wang, Shaoyang
Liu. Comparison of principal component regression (PCR) and partial least square regression
(PLSR) modeling methods for quantifying polyethylene (PE) in recycled polypropylene
(rPP) with near-infrared spectrometry (NIR). International Journal of Polymer Analysis and Characterization 2024, 29, 56-63.
2024 Presentations
Shaoyang Liu and Pixiang Wang. Rapid and accurate analysis of contaminants in recycled
polypropylene with Raman and NIR spectrometries. ACS Fall 2024 Meeting. Denver, CO,
August 18-22, 2024.
Somayeh Mohammadi, Mojtaba Enayati. Magnetic Ionic Liquid Catalyst Functionalized
with Antimony(III) Bromide for Effective Glycolysis of Polyethylene Terephthalate.
American Chemical Society: Inaugural East Alabama/West Georgia Local Section Research
Symposium 2024. Troy, AL. February 23, 2024.
Aboulfazl Barati. Enhancing Compatibility and Performance of PBAT/PHB Blends with
PE-g-MA Reactive Compatibilizer. American Chemical Society: Inaugural East Alabama/West
Georgia Local Section Research Symposium 2024. Troy, AL. February 23, 2024.
Meet Chapani, Zhiyong Wang. Chemical Upcycling of Waste Water Bottles into Metal-organic
Framework Compounds. American Chemical Society: Inaugural East Alabama/West Georgia
Local Section Research Symposium 2024. Troy, AL. February 23, 2024.
Aboulfazl Barati. Exploring the Recycling Potential of PET Reinforced with Silane
Surface Treated Hemp Fiber. American Chemical Society: Inaugural East Alabama/West
Georgia Local Section Research Symposium 2024. Troy, AL. February 23, 2024.
Mojtaba Enayati, Somayeh Mohammadi. Sustainable PET Waste Recycling: Thermolysis of
PET Water Bottle Labels Provide Catalyst for PET Waste Recycling. American Chemical
Society: Inaugural East Alabama/West Georgia Local Section Research Symposium 2024.
Troy, AL. February 23, 2024.
Martin G. Bouldo, Mojtaba Enayati. Polypropylene Face Mask Recycling: Addressing a
COVID Outbreak Side Effect. 2024 Alabama Academy of Science Annual Meeting. Jacksonville,
AL. February 21-23, 2024 (won First Place for the undergraduate poster competition
in the Chemistry Section).
Deacon Godfrey, Aboulfazl Barati, Erfan Dashtimoghadam. Rheological and Mechanical
Behavior of Maleated Recycled High-Density Polyethylene. 2024 Alabama Academy of Science
Annual Meeting. Jacksonville, AL. February 21-23, 2024 (won Second Place for the undergraduate
poster competition in the Environmental and Earth Science Section).
Dayne Long, Shaoyang Liu, Pixiang Wang. Deconvolution of GPC chromatograms of PP-PE
mixtures with multiple-band IR detector. 2024 Alabama Academy of Science Annual Meeting.
Jacksonville, AL. February 21-23, 2024 (won Second Place for the undergraduate paper
competition in the Environmental and Earth Science Section).
Emily Sustarich, Shaoyang Liu, Pixiang Wang. Survey of Molecular Weight Distribution
of Post-Consumer Recycled Polypropylene and Polyethylene. 2024 Alabama Academy of
Science Annual Meeting. Jacksonville, AL. February 21-23, 2024.
2023 Journal Publications
TROY faculty publications
A Sustainable PET Waste Recycling: Labels from PET Water Bottles Used as a Catalyst
for the Chemical Recycling of the Same Bottles
Mojtaba Enayati, Somayeh Mohammadi, Martin G. Bouldo. Sustainable PET Waste Recycling:
Labels from PET Water Bottles Used as a Catalyst for the Chemical Recycling of the
Same Bottles. ACS Sustainable Chemistry & Engineering 2023.
Abstract: We report using a waste material, poly(ethylene terephthalate) (PET) water bottle
labels, for the chemical recycling of the same PET water bottles. The solid fillers
used for the manufacturing of the packaging labels were recovered by thermolysis in
an electrical furnace at 600, 800, and 1000 掳C with 13.5, 12.0, and 10.4 wt % recovery.
Characterization of the solid residue showed the presence of calcium carbonate, calcium
oxide, and titanium dioxide, which are typical fillers used for packaging film manufacturing,
such as water bottle labels. These solid residues were then used as a catalyst for
PET depolymerization by glycolysis, in which the catalyst recovered from bottle labels
and shredded PET reacted in the presence of excess ethylene glycol at 200 掳C. The
reaction mixtures were analyzed for PET conversion and the yield of the bis(2-hydroxyethyl)terephthalate
(BHET) monomer as the final product of the glycolysis reaction to determine the efficiency
of the catalyst. Our results show that the catalyst prepared at 800 掳C (Cat-800) has
the best performance and provides a 100% PET conversion with a 95.8% BHET yield with
a 1.0 wt % loading in 1.5 h. The catalyst from the PET water bottle labels is nontoxic,
readily available, cost-effective, environmentally friendly, and can be used as a
model for the self-sufficient chemical recycling of PET via glycolysis.
Magnetic ionic liquid catalyst functionalized with antimony (III) bromide for effective
glycolysis of polyethylene terephthalate
Somayeh Mohammadi, Mojtaba Enayati. Magnetic ionic liquid catalyst functionalized
with antimony (III) bromide for effective glycolysis of polyethylene terephthalate.
Waste Management 2023, 170, 308-316.
Abstract: In a previous study, we demonstrated the efficient depolymerization of polyethylene
terephthalate (PET) through glycolysis using antimony (III) oxide, a commonly used
catalyst in PET synthesis. In the present research, we introduce a novel approach
involving the synthesis of a magnetic bifunctional ionic liquid, Fe3O4@PMIM.SbBr4,
containing only 2.2 wt% of antimony. The aim is to reduce the required antimony dosage
for the reaction and enable its facile recovery and reuse. By employing this catalyst
in PET chemical recycling through glycolysis to generate bis (2-hydroxyethyl) terephthalate
(BHET) monomer, we achieved 100% PET conversion with a 96.4% yield and selectivity
for BHET. This outcome was obtained using a catalyst loading of 6.0 wt% at 200 掳C
and 0.6 bar in a high-pressure reactor. We explored the impact of catalyst loading
on BHET yield and conducted a comparative assessment of the Fe3O4@PMIM.SbBr4 catalyst
against antimony (III) bromide, and another synthesized unsupported antimony-containing
ionic liquid. Our results revealed the superior catalytic activity of the magnetic
ionic liquid catalyst in PET glycolysis. The utilization of this catalyst offers promising
potential for PET glycolysis due to its effortless separation using an external magnet,
ability to produce highly pure BHET, and recyclability for repetitive use.
Controlled Glycolysis of Poly(ethylene terephthalate) to Oligomers under Microwave
Irradiation Using Antimony(III) Oxide
Somayeh Mohammadi, Martin G. Bouldo, Mojtaba Enayati. Controlled Glycolysis of Poly(ethylene
terephthalate) to Oligomers under Microwave Irradiation Using Antimony(III) Oxide.
ACS Applied Polymer Materials 2023, 5, 6574鈥�6584.
Abstract: We report here the production of higher-order oligomers from the glycolysis of poly(ethylene
terephthalate) (PET) by using microwave irradiation in a controlled fashion, instead
of its fully glycolyzed product, bis(2-hydroxyethyl)terephthalate (BHET). We show
that different catalysts can generate either BHET as the ultimate glycolysis product
or higher oligomers of PET under microwave irradiation. Depolymerization of waste
PET with an average degree of polymerization (DP) of 417 from water bottles was performed
in the presence of 0.25 wt % antimony(III) oxide (Sb2O3) as the catalyst at 240 掳C and 400 W microwave power, resulting in an oligomer yield
of 96.7% with an average DP of 37. Under these conditions, the conversion of PET to
oligomers reached 100% in only 5 min at 240 掳C (with a 10 min ramping time) and with
a ethylene glycol to PET weight ratio of 2.5. In comparison, under the same reaction
conditions, 0.04 wt % of zinc acetate (Zn(OAc)2), a well-known catalyst for PET glycolysis, produces only the BHET monomer in 96.3%
yield. Our results demonstrated that by using Sb2O3, the same catalyst that is used extensively for PET synthesis from BHET, under microwave
irradiation, the PET glycolysis can be controlled to produce higher PET oligomers
as an alternative for a complete chemical depolymerization to the BHET monomer. These
oligomers are more suitable for being used as additives for many applications and
to produce high-quality second-generation products, including regenerated PET.
Nitrile rubber/peroxide treatment transformed recycled polyethylene into mechanically
improved materials
Arun Ghosh, Ashik Cheruvathery Kannan. Nitrile rubber/peroxide treatment transformed
recycled polyethylene into mechanically improved materials. SPE polymers In press.
Abstract: The recycled high-density polyethylene (rHDPE) feedstock containing calcium carbonate
(CaCO3) mineral was obtained from post-consumer single-use grocery bags. This feedstock
is transformed into new composite materials with improved mechanical properties using
a high-shear compounding process. The rHDPE/CaCO3 feedstock is injected into the high-shear polymer mixer and blended with acrylonitrile-butadiene
copolymer or nitrile rubber (up to 10鈥墂t%) and crosslinked with dicumyl peroxide.
The resultant materials exhibit high mechanical performance, with a maximum tensile
strength of 20.3鈥塎Pa, stiffness of 1262鈥塎Pa, and impact strength of 63鈥塳J/m2. These mechanical properties are profoundly higher than those of neat rHDPE feedstock.
Notably, the post-consumer plastic bags contain a high amount of CaCO3 mineral of approximately 30鈥墂t% (13鈥塿ol%), impacting the materials' mechanical properties
with additives such as nitrile rubber. In addition, the materials' melt-rheology,
viscoelastic, and phase morphology are analyzed. The melt-rheological characteristics
indicate that the materials' complex viscosity and storage modulus are frequency-dependent,
demonstrating the thermoplastic nature of the composite materials and the possibility
of thermomechanical recyclability of the materials. However, treating rHDPE/nitrile
rubber blends with peroxide creates resistance to the melt-flow of the materials.
Reactive Blending of Recycled Polyethylene Terephthalate/Recycled Polypropylene: Kinetics
Modeling of Non-isothermal Crystallization
Abstract: Plastics were developed to change our world for the better. However, plastic pollution
has become a serious global environmental crisis. Thermoplastic polyesters and polyolefins
are among the most abundant plastic waste. This work presents an in-depth non-isothermal
crystallization kinetics analysis of recycled post-consumer poly(ethylene terephthalate)
(rPET) and recycled polypropylene (rPP) blends prepared through reactive compounding.
The effect of pyromellitic dianhydride (PMDA) on crystallization kinetics and phase
morphology of rPET/rPP blends was investigated by differential scanning calorimetry
(DSC) and microscopy techniques. DSC results showed that increasing rPP content accelerated
rPET crystallization while reducing crystallinity, which indicates the nucleation
effect of the rPP phase in blends. Further, it was found that the incorporation of
PMDA increased the degree of crystallinity during non-isothermal crystallization,
even though the rate of crystallinity decreased slightly due to its restriction effects.
The non-isothermal crystallization kinetics was analyzed based on the theoretical
models developed by Jeziorny, Ozawa, Mo, and Tobin. The activation energy of the crystallization
process derived from Kissinger, Takhor, and Augis鈥揃ennett models was found to increase
in rPET/rPP blends with increasing PMDA due to hindered dynamics of the system. Rheological
measurements revealed that rPET melt viscosity is remarkably increased in the presence
of PMDA and reactive blending with rPP relevant for processing. Moreover, nanomechanical
mapping of the rPP phase dispersed in the rPET matrix demonstrated the broadening
of the interfacial domains after reactive blending due to the branching effect of
PMDA. Findings from this study are essential for the recycling/upcycling thermoplastics
through non-isothermal fabrication processes, such as extrusion and injection molding,
to mitigate the lack of sorting options.
Synthesis and Characterization of Quercetin-Iron Complex Nanoparticles for Overcoming
Drug Resistance
Lucas Prestianni, Eric Espinal, Sarah F. Hathcock, Nadine Vollmuth, Pixiang Wang,
Robert A. Holler, Shaoyang Liu, Brandon J. Kim, Yuping Bao. Synthesis and Characterization
of Quercetin-Iron Complex Nanoparticles for Overcoming Drug Resistance. Pharmaceutics
2023, 15, 1041.
Abstract: Quercetin, one of the major natural flavonoids, has demonstrated great pharmacological
potential as an antioxidant and in overcoming drug resistance. However, its low aqueous
solubility and poor stability limit its potential applications. Previous studies suggest
that the formation of quercetin-metal complexes could increase quercetin stability
and biological activity. In this paper, we systematically investigated the formation
of quercetin-iron complex nanoparticles by varying the ligand-to-metal ratios with
the goal of increasing the aqueous solubility and stability of quercetin. It was found
that quercetin-iron complex nanoparticles could be reproducibly synthesized with several
ligand-to-iron ratios at room temperature. The UV-Vis spectra of the nanoparticles
indicated that nanoparticle formation greatly increased the stability and solubility
of quercetin. Compared to free quercetin, the quercetin-iron complex nanoparticles
exhibited enhanced antioxidant activities and elongated effects. Our preliminary cellular
evaluation suggests that these nanoparticles had minimal cytotoxicity and could effectively
block the efflux pump of cells, indicating their potential for cancer treatment.
Enhancing the thermoplastic behavior and mechanical performance of recycled HDPE/CaCO3
composite using oxidized polyethylene
Arun Ghosh. Enhancing the thermoplastic behavior and mechanical performance of recycled
HDPE/CaCO3 composite using oxidized polyethylene. Journal of Applied Polymer Science 2023, e53923.
Abstract: There is a growing interest in sustainable materials based on recycled or natural
feedstocks for the circular economy. Ideally, thermoplastic materials are anticipated
to show appropriate melt-flow behavior for thermo-mechanical recycling, good melt
stability, and mechanical performance. Thermoplastic polyolefins such as polyethylenes
are used as single-use packaging materials and generate environmental concerns. This
article reports the melt-processing and characterization of composite materials based
on recycled high-density polyethylene (rHDPE) and naturally abundant calcium carbonate
(CaCO3) mineral at various mass ratios such as 70/30, 50/50, and 30/70. Oxidized polyethylene
(OPE) is used as an additive, with 20 wt% replacement of rHDPE, to improve the materials'
mechanical performance and thermoplastic behavior. Various characteristics such as
tensile, viscoelastic, melt-flow, phase morphology, and thermomechanical recyclability
of the materials are analyzed. It reveals that composites with high CaCO3 content compatibilized with OPE show improved tensile strength and modulus. For example,
the composite based on 10/70/20 (wt%) of rHDPE/CaCO3/OPE shows an average tensile strength of 27.4 MPa and Young's modulus of 4.5 GPa,
in contrast to the rHDPE sample, which shows an average tensile strength of 12.4 MPa
and Young's modulus of 967 MPa. Notably, adding OPE decreases the melt-viscosity of
the rHDPE/CaCO3 materials, thus improving the composites' melt-flow and thermoplastic behavior. This
study indicates the possibility of developing natural CaCO3-rich polymer composites with thermoplastic behavior for real-life applications with
superior mechanical and melt-flow properties suitable for thermomechanical recycling.
Comparison of NIR and Raman spectrometries as quantitative methods to monitor polyethylene
content in recycled polypropylene
Pixiang Wang, Ke Zhan, Xueqi Wang, Yucheng Peng, Shaoyang Liu. Comparison of NIR
and Raman spectrometries as quantitative methods to monitor polyethylene content in
recycled polypropylene. Polymer Testing 2023, 119, 107938.
Abstract: Recycled polypropylene (rPP) often contains a small amount of polyethylene (PE),
which frequently compromises the performance of the material and needs to be monitored.
In the current work, near-infrared (NIR) and Raman spectrometries were investigated
to establish convenient and accurate methods to analyze PE content in rPP. Various
spectrum pretreatment methods, including multivariate scattering correction (MSC),
standard normal variate transformation (SNV), baseline correction, normalization,
smoothing, and first derivative, were tested to reduce noise and improve spectrum
quality for partial least squares (PLS) regression. Forward and backward interval
partial least squares (FiPLS/BiPLS) methods were employed to optimize spectral range
selection. The best NIR model had an R2 of 0.9971 and a root-mean-square error of prediction (RMSEP) of 0.2761 PE wt% in
independent validation, and the best Raman model achieved an R2 of 0.9945 and an RMSEP of 0.3818 wt%. The models were further validated with rPP
samples. The best Raman model obtained an R2 of 0.9954 and an RMSEP of 0.2404 wt% on non-colored rPP, but it failed to be applied
to colored rPP. The best NIR model had a slightly weaker performance on non-colored
rPP (R2: 0.9246; RMSEP: 0.9710 wt%), but it was successfully applied to grey commercial rPP
samples. This work would help quality assurance of recycled PP materials.
Non-isothermal crystallization kinetics of polypropylene homopolymer/impact copolymer
composites
Pixiang Wang, Yifen Wang, Xueqi Wang, Yucheng Peng, Shaoyang Liu. Non-isothermal
crystallization kinetics of polypropylene homopolymer/impact copolymer composites.
Journal of Thermal Analysis and Calorimetry 2023, 148, 3311鈥�3323
Abstract: Crystallization kinetics of an isotactic homopolymer polypropylene (HPP), an impact
copolymer polypropylene (ICPP), and their composites were studied in this work. The
Avrami鈥揓eziorny and Mo models successfully described the crystallization process.
When the ICPP content increased, the crystallization rate first increased and then
decreased with the highest crystallization rate at the ICPP content of 60 mass%. The
nucleation activity kept increasing with the rise of the ICPP content, demonstrating
that the rubber phase in the ICPP acted as a nucleating agent and prompted the nucleation
process. The decrease in crystallization rate when the ICPP content was higher than
60 mass% might be caused by the decrease in chain mobility and the increase in crystal鈥揷rystal
interactions. When the ICPP content exceeded 60 mass%, the crystallization activation
energy increased evidently, indicating lower polymer chain mobility. Meanwhile, the
Avrami exponent, n, decreased, suggesting limited crystal growth space and higher
crystal鈥揷rystal interactions. The nucleation activity showed high correlations to
the mechanical and thermal properties of the materials. The Avrami exponent also had
relatively high correlations to these properties. The results improved the understanding
of the crystallization behaviors of the HPP鈥揑CPP composites and helped predict their
potential mechanical behavior changes.
Green Chemical Synthesis of Size鈥慍ontrolled Gold Nanodisk Governed by Hydrophilic
Protein/Peptide鈥慠ich Aqueous Extract from American Cockroach, Periplaneta americana
James Lee Cho, Shaoyang Liu, Pixiang Wang. Green Chemical Synthesis of Size鈥慍ontrolled
Gold Nanodisk Governed by Hydrophilic Protein/Peptide鈥慠ich Aqueous Extract from American
Cockroach, Periplaneta americana. BioNanoScience 2023, 13, 167-175.
Abstract: Gold nanodisks (AuNDs) were successfully synthesized by a green biochemical method
in aqueous American cockroach (Periplaneta americana) extract (AACE) solution. The
high content of water-soluble bio-organic compounds such as hydrophilic proteins and
polypeptides in the AACE solution acted as reducing and stabilizing agents for AuND
formation due to the interaction with Au 3+ ion precursors. The size (the diameter
and the thickness) of the synthesized AuNDs was highly dependent on the concentration
(%, m/v) of the AACE solution and was inversely proportional. The average diameter
and the thickness of the majority of the AuNDs decreased from 198 to 21 nm and from
48 to 4.3 nm respectively as AACE concentration increases from 0.40 to 1.5%. The method
developed in this work provides a convenient, safe, eco-friendly, and cost-efficient
mean to produce size-controlled AuNDs.
2023 Presentations
Aboulfazl Barati, Somayeh Mohammadi, Mojtaba Enayati, Erfan Dashtimoghadam. A Sustainable
Hybrid Catalyst to Depolymerize Recycled Polyethylene Terephthalate. 2023 AIChE Annual
Meeting. Orlando, FL. November 5-10, 2023.
Somayeh Mohammadi, Martin G. Bouldo, Mojtaba Enayati. Polyethylene Terephthalate Depolymerization:
Controlled Glycolysis to Oligomers via Microwave Irradiation Using Antimony (III)
Oxide. 2023 AIChE Annual Meeting. Orlando, FL. November 5-10, 2023.
Aboulfazl Barati, Deacon S. Godfrey, Erfan Dashtimoghadam. Reactive Compatibilization
of Recycled Polyethylene Terephthalate/Recycled Rubber Particles Blends. 2023 AIChE
Annual Meeting. Orlando, FL. November 5-10, 2023.
Pixiang Wang, Shaoyang Liu. Comparison of principal component regression (PCR) and
partial least square (PLS) modeling methods for quantifying polyethylene (PE) in recycled
polypropylene (rPP) with near-infrared spectrometry (NIR). ACS Fall 2023 meeting.
San Francisco, CA, August 13-17, 2023.
Arun Ghosh. Enhancing thermoplastic behavior and mechanical performance of calcium
carbonate-based materials. Materials Today Conference (Elsevier). Singapore, August
2 -5, 2023.
Arun Ghosh, Environmentally sustainable materials based on recycled polyethylene and
calcium carbonate. Rotary Club of Jasper. Bevill State Community College, Jasper,
AL. July 18, 2023.
Aboulfazl Barati, Erfan Dashtimoghadam. Effect of Reactive and Non-Reactive Coupling
Agents on Mechanical Properties of Recycled Polyethylene Terephthalate Filled With
Ground Tire Powder. 2023 Society of Plastics Engineers Annual Technical Conference
(SPE ANTEC). Denver, Co, March 27-30, 2023.
Somayeh Mohammadi, Mojtaba Enayati. Antimony Oxide as a catalyst for glycolysis of
polyethylene terephthalate (PET) waste. 2023 Society of Plastics Engineers Annual
Technical Conference (SPE ANTEC). Denver, Co, March 27-30, 2023.
Pixiang Wang, Yucheng Peng, Shaoyang Liu. Study of the non-isothermal crystallization
kinetics of polypropylene homopolymer/impact copolymer composites. 2023 Society of
Plastics Engineers Annual Technical Conference (SPE ANTEC). Denver, CO, March 27-30,
2023.
Meet Chapani, Somayeh Mohammadi, Mojtaba Enayatinook, Zhiyong Wang. Catalysis of the
Chemical Recycling of Polyethylene Terephthalate (PET) with Metal-organic Framework
Compounds Derived from Waste Water Bottles. The 100th Alabama Academy of Science Annual
meeting. Birmingham, AL, March 8-10, 2023 (won the First Place in undergraduate paper
competition in the Environmental and Earth Science section).
Dayne Long, Pixiang Wang, Shaoyang Liu. Monitoring Calcium Carbonate Content in Recycled
Polypropylene with Raman Spectrometry. The 100th Alabama Academy of Science Annual
meeting. Birmingham, AL, March 8-10, 2023 (won the First Place in undergraduate poster
competition in the Environmental and Earth Science section).
Pixiang Wang, Shaoyang Liu. Study of near infrared spectroscopy as a quantitative
method for monitoring polyethylene content in recycled polypropylene. The 100th Alabama
Academy of Science Annual meeting. Birmingham, AL, March 8-10, 2023.
Aboulfazl Barati, Erfan Dashtimoghadam. Effect of Chain Extension and Branching on
Thermal Degradation of Recycled Polyethylene Terephthalate/ Recycled Polypropylene
Blends. SPE International Polyolefins Conference, Galveston, TX, March 5-8, 2023.
Arun Ghosh. Recycling single-use plastics into high-performance materials. Trojans
Talk Research, 星空传媒, Troy, AL. January 25, 2023.
2022 Journal Publications
TROY Faculty Publications
Dual catalytic activity of antimony (III) oxide: The polymerization catalyst for synthesis
of polyethylene terephthalate also catalyze depolymerization
Somayeh Mohammadi, Mojtaba Enayati. Dual catalytic activity of antimony (III) oxide:
The polymerization catalyst for synthesis of polyethylene terephthalate also catalyze
depolymerization. Polymer Degradation and Stability 2022, 206, 110180.
Abstract: In this study polyethylene terephthalate (PET) waste from drinking water bottles
was converted to bis(2-hydroxyethyl) terephthalate (BHET) in the presence of antimony
(III) oxide (Sb2O3) as the catalyst and excess ethylene glycol (EG). The yield of BHET, using 0.5 wt%
of the catalyst, under 200掳C and 2.1 bar was 97.5%, achieved in only 1 h. The crude
of the reaction and the purified monomer was characterized by differential scanning
calorimetry, infrared spectroscopy, high pressure liquid chromatography, thermogravimetric
analysis, and nuclear magnetic resonance. The influences of reaction parameters, such
as the catalyst loading, reaction time, EG:PET weight ratio, and reaction pressure
on the yield of BHET was investigated. In addition, the activity of this catalyst
was compared to zinc acetate, antimony (III) acetate, and antimony (V) oxide, demonstrating
the highest catalytic activity of Sb2O3 for PET glycolysis. Since Sb2O3 is one of the catalysts for the industrial synthesis of PET, the results from this
work can open up a venue for the synthesis of repolymerized PET from waste PET in
the same glycolysis reactor.
Effects of chemical and autoclave sterilization treatments on medical personal protective
equipment made of nonwoven polypropylene fibers for recycling
Pixiang Wang, William D. Cutts, Haibin Ning, Selvum Pillay, Shaoyang Liu. Effects
of chemical and autoclave sterilization treatments on medical personal protective
equipment made of nonwoven polypropylene fibers for recycling. Journal of Polymer
Research 2022, 29, 360.
Abstract: Medical personal protective equipment (PPE) made from nonwoven thermoplastic fibers
has been intensively used, resulting in a large amount of biohazardous waste. Sterilization
is indispensable before recycling medical waste. The aim of this work is to evaluate
the effects of the decontamination treatments and help properly recycle the PPE materials.
The study investigated the effects of three disinfection treatments (NaClO, H2O2, and autoclave) on chemical composition, molecular weight, thermal properties, crystallinity,
crystallization kinetics, and mechanical tension of three types of PPE (Gown #1, Gown
#2, and Wrap) made of isotactic polypropylene fibers. The chemical compositions of
the materials were not evidently affected by any of the treatments. However, the Mw of the polymers decreased about 2-7% after the treatments, although the changes were
not statistically significant. The treatments barely affected the melting and crystallization
temperatures and the maximum force at break, but they tended to elevate the thermal
degradation temperatures. Although the treatments did not notably influence the crystallinities,
crystallization rates and crystal growths were altered based on the Avrami model regression.
Since the detected changes would not significantly affect polymer processing, the
treated materials were suitable for recycling. Meanwhile, evident differences in the
three types of raw materials were recorded. Their initial properties fluctuated notably,
and they often behaved differently during the treatments, which could affect recycling
operation. Recyclers should test and sort the raw materials to assure product quality.
The results in this study provide fundamental data for recycling medical PPE to reduce
its environmental footprint.
Formulating Polypropylene with Desired Mechanical Properties through Melt Compounding
of Homopolymer and Impact Copolymer
Yucheng Peng, Shaoyang Liu, Pixiang Wang, Yifen Wang, Xueqi Wang. Formulating Polypropylene
with Desired Mechanical Properties through Melt Compounding of Homopolymer and Impact
Copolymer. Polymer Crystallization 2022, 2022, 3084446.
Abstract: Many grades of homopolymer polypropylene (HPP) and impact copolymer PP (ICPP) with
a wide range of mechanical properties have been developed for a variety of applications
in different industrial sectors. Management of this wide range of materials is a challenge
for material suppliers and manufacturers and product developers. This research was
to provide insights for managing material supplies through formulating PP with specific
mechanical properties using melt compounding of ICPP and HPP. ICPP and HPP were compounded
with an internal mixer at different ratios and then the mixtures were injection molded
into specimens for characterization. The mechanical behaviors, fracture surfaces,
and thermal properties of the mixtures were then characterized. The fracture surface
results indicated that the morphologies of the rubber particles in ICPP changed after
compounding with HPP, leading to different mechanical and thermal behaviors of the
mixtures. Notched and unnotched impact strengths increased linearly with increasing
ICPP contents. The crystallization peak temperatures increased linearly with increasing
ICPP contents while the degrees of crystallinity of the mixtures decreased linearly.
The thermal compounding process and the original material properties mainly determine
the final mixture behaviors, and the mixture properties can be predicted based on
the weight ratios of the two components.
Organosolv Lignin Improved Thermoplastic Elastomeric Behavior of Polyethylene/Polyisoprene
Blend
Abstract: Thermoplastic elastomers are considered the fastest-growing elastomers in recent
years because of their thermomechanical recyclability, in contrast to traditional
thermoset rubbers. Polyolefins such as low-density polyethylene (LDPE) show low mechanical
properties, particularly poor elongation when compared with an elastomer or rubber.
In this study, LDPE resin is converted to highly ductile rubber-like materials with
high elongation and low modulus properties on blending with polyisoprene rubber (IR),
followed by treating with dicumyl peroxide as a curing agent and organosolv lignin
as an additive. The technique of high shear melt-mixing, in conjunction with vulcanization
or crosslinking using organic peroxide, is used to develop hybrid materials based
on the LDPE/IR blend at a 70/30 mass ratio, where LDPE is replaced partly with lignin.
Various characteristics such as tensile, viscoelasticity, melt flow, crystallinity,
and phase morphology of the materials are analyzed. As expected, vulcanization with
peroxide can improve the mechanical performance of the LDPE/IR blends, which is further
improved with the application of lignin (2 to 5 wt. %), particularly tensile strain
is profoundly increased. For example, the average values of the tensile strength,
the modulus, and the ultimate elongation of neat LDPE resin are 7.8 MPa, 177 MPa,
and 62%, respectively, and those of LDPE/IR/lignin/DCP 65/30/05/2 are 8.1 MPa, 95
MPa, and 238%, respectively. It indicates that the application of lignin/DCP has a
profound effect on improving the ductility and elastomeric characteristics of the
materials; thus, this material can have the potential to replace traditional rubber
products.
2022 Presentations
James Cho, Shaoyang Liu, Pixiang Wang, and Martin Bouldo. Green Biochemical Synthesis
of Silver Nanoparticle with Hydrophilic proteins/peptides rich aqueous extract of
American Giant Millipede, Narceus americanus. Applied Polymer Technology Extension
Consortium (APTEC) 2022 Annual Meeting. Baton Rouge, LA, November 9, 2022.
Arun Ghosh, Ashik C. Kannan, 鈥淢echanical recycling of single-use polyethylene into
materials with variable properties鈥� Proceedings of ANTEC 鈥� Society of Plastics Engineers
(SPE ANTEC庐 2022), Charlotte, NC, June 14 -16, 2022.
Amber Johanson, Jarome Amos, Taylor Chambers and Shaoyang Liu. Investigation of chemical
composition of post-consumer recycled polypropylene with spectrometric methods. The
99th Alabama Academy of Science Annual meeting. Athens, AL, USA. March 16-18, 2022.
Arun Ghosh, 鈥淢echanical recycling of single-use polyethylene into nanocomposites鈥�,
2022 SPE International Polyolefins Conference, Galveston, TX, Feb 13- 16, 2022.
2021 Journal Publications
TROY Faculty Publications
Recycled polyethylene/polycarbonate blends compatibilized with oxidized polyethylene/CaCO3
Arun Ghosh. Recycled polyethylene/polycarbonate blends compatibilized with oxidized
polyethylene/CaCO3. Journal of Applied Polymer Science (2021) e51919.
Abstract: Polyethylene (PE) and polycarbonate (PC) are not thermodynamically miscible, and
they tend to be phase-separated during melt-processing, because of significant incompatibility
in structures and properties. Interestingly, minerals such as CaCO3 are used in PE-based supermarket bags for improving surface characteristics. In this
study, recycled low-density polyethylene (LDPE) and PC resins are melt-blended at
50/50鈥墂t%, without and with oxidized polyethylene (OPE) as a compatibilizer. A parallel
experiment is conducted with 50/50 blends of virgin LDPE and PC resins. Various characteristics
such as tensile, viscoelastic, melt-flow, and phase morphology of the materials are
analyzed. The 50/50 blend of recycled LDPE/PC blend shows an average tensile strength
of 15鈥塎Pa, which increases to 24鈥塎Pa on the addition of 5 wt% OPE, where total recycled
content is 95鈥墂t% including 15鈥墂t% CaCO3. Notably, the presence of CaCO3-based filler in recycled LDPE has a profound effect in improving the mechanical performance
of the materials.
Performance modifying techniques for recycled thermoplastics
Abstract: Petro-derived commodity thermoplastics are relatively inexpensive, lightweight, and
non-biodegradable materials, which can be readily molded at high temperatures into
a range of products. The manufacturing of such thermoplastic resins and products has
increased dramatically over the last 70 years. The plastics based on polyolefins,
polystyrenes, and polyesters occupy the largest share (80%) of the world's plastic
markets. However, the disposal of waste plastics has created considerable environmental
concerns. Therefore, environment protection agencies and plastic manufacturers are
constantly seeking appropriate techniques for recycling or upcycling waste plastics
into new products. In recent years, the recycling rates are approximately 9 to 15%
out of total plastics produced annually in the United States and Europe, which are
predominantly limited to individual plastic fractions such as HDPE and PET. The recycling
process is associated with various expensive and time-consuming sorting techniques,
which are not economically attractive to the recycling industries. A significant issue
is when multiple plastics are blended, they often are not chemically compatible, resulting
in phase separation and inferior-quality materials. Therefore, it is important to
apply certain performance modifiers during the re-extrusion of waste thermoplastics,
which include compatibilizers, coupling agents, impact modifiers, and many others.
There are different additives and techniques available, suitable to improve the mechanical
and other associated properties of polymer blends and composites, and these can also
be used for improving the performance of recycled thermoplastics. This review article
summarizes various chemical additives and approaches, which can be used in thermomechanical
upcycling of waste thermoplastics to new materials with superior mechanical performance
via improving interfacial adhesion or phase homogeneity of polymer blends.
Comparison of nanostructure and nanomechanical properties of cast and air sides of
polyimide films from different manufacturers
Shaoyang Liu, Taylor G. Chambers, William D. Cutts. Comparison of nanostructure and
nanomechanical properties of cast and air sides of polyimide films from different
manufacturers. Micron 2021, 145, 103059.
Abstract: Polyimide films are widely applied in harsh environments because of their outstanding
performance. High-quality polyimide films are often manufactured through a two-step
process. The complicated procedure results in different properties on the two sides,
i.e., the air side and cast side of the films, and the quality of products from different
manufacturers varies notably. In the present work, polyimide films with two thicknesses
(1 and 2 mm) from four manufacturers were investigated. Atomic force microscope and
FT-IR spectrometer were employed to monitor morphology, roughness, nanomechanical
properties, and corresponding relative imidization degree on the two sides of each
film. Statistical tools were applied to analyze the data. T-test suggests that the
two sides of the same film were significantly different in roughness, DMT modulus,
and relative imidization degree (p < 0.05). The roughness on the air side was consistently
smaller than that of the cast side. ANOVA was used to compare differences among the
manufacturers. Manufacturer B provided the smoothest films with the highest DMT moduli
and imidization degrees. A positive correlation was found between the DMT modulus
and imidization degree (r = 0.7330). Nanostructure and nanomechanical properties could
affect the quality of the film. Striped morphology and adhesion were found on the
cast side of the 2-mm film from manufacturer D, which compromised the film tension
in the direction perpendicular to the strips. Investigations of morphology and mechanical
properties of polyimide film at the nanoscale would help us better characterize the
film, assure its quality, and select suitable film and side for proper applications.
2021 Presentations
Zhiyong Wang, Zephan Vickery, Emily Strickland. Recycling and Upcycling of Waste Plastics
with Hemp Fibers. 2021 ACS Southeastern Regional Meeting, Birmingham, AL, November
10-13, 2021.
Arun Ghosh, Ashik C. Kannan. Upcycling of single-use polyethylene into high strength
materials via reactive compounding. Southeastern Regional Meeting of the American
Chemical Society, Birmingham, AL, November 10-13, 2021.
Pixiang Wang, Yucheng Peng and Shaoyang Liu. Crystallization Kinetics of Mixtures
of Polypropylene Homopolymer and Impact Copolymer. 2021 ACS Southeastern Regional
Meeting, Birmingham, AL, November 10-13, 2021.
Taylor G. Chambers and Shaoyang Liu. AFM investigation of the effects of disinfection
treatments on polypropylene personal protective equipment (PPE) materials. 2021 ACS
Southeastern Regional Meeting, Birmingham, AL, November 10-13, 2021.
Arun Ghosh. Organosolv lignin and its use in modifying polyethylene thermoplastic.
International Webinar Series, InnoRenew CoE and PACK-NIN project, Slovenia. July 20,
2021.
William D. Cutts, Haibin Ning, Selvum Pillay and Shaoyang Liu. Thermal degradation
of nylon and polyphenylene sulfide 3D printing filaments under operating temperatures.
ACS Spring 2021 Virtual Meeting. April 5-30, 2021.
2020 Journal Publications
TROY Faculty Publications
Analysis of volatile compounds causing undesirable odors in a polypropylene - high-density
polyethylene recycled plastic resin with solid-phase microextraction
Jon Fuller, David White, Huijun Yi, Jason Colley, Zane Vickery, Shaoyang Liu. Analysis
of volatile compounds causing undesirable odors in a polypropylene - high-density
polyethylene recycled plastic resin with solid-phase microextraction. Chemosphere
2020, 260: 127589.
Abstract: Although recycled plastics provide a low-cost and environmentally friendly alternative
for many applications, their desirability is significantly limited by the presence
of unpleasant odors from volatile organic compounds (VOCs). In this work, a headspace
solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry
(GC-MS) method was optimized to analyze volatile compounds from an odorous recycled
plastic resin which was roughly composed of 85-90% polypropylene (PP) and 15-10% high-density
polyethylene (HDPE). A large variety of aliphatic hydrocarbons and 13 additive residues
were detected. Statistical tools were employed to screen the VOCs and successfully
identified three components, i.e., 2,4-dimethyl-heptane, 4-methyl-octane and octamethylcyclotetrasiloxane
(D4), which were significantly related to the odor intensity of the recycled plastic
resin (p-values < 0.05). 2,4-Dimethyl-heptane has a strong, pungent plastic smell,
which is very similar to the odor of the recycled resin. It is identified as a major
source of the odor. Past relevant research has not been able to establish a direct
link between an odorous compound and the undesirable odor of recycled plastic until
now. 4-Methyl-octane was highly corelated to 2,4-dimethyl-heptane and somewhat contributed
to the odor. D4 does not have an odor, but it may serve as an indicator of some odorous
residues from personal care products.
2020 Presentations
Taylor G. Chambers and Shaoyang Liu. AFM Analysis of Rq and Ra Values of Polyimide
Film. 8th Applied Polymer Technology Extension Consortium (APTEC) annual research
symposium. Tulane University, New Orleans, LA, USA. November 6-7, 2020.
Soumitra Ganguly, Arun Ghosh. Thermal transition behavior of thermoplastics after
exposing to high Temperature. 2020 APTEC Research Symposium (Virtual Poster Presentation),
Tulane University, New Orleans, LA. November 6, 2020.
Du H. Luu, Logan C. Ledbetter, Shaoyang Liu. Thermal degradation of polyethylene and
polypropylene under recycling processing temperature 鈥撯�� a study of volatile compound
profile. ACS Fall 2020 Virtual Meeting & Expo, August 17-20, 2020.
Haibin Ning, Yongzhe Yan, Doni Thomas, Siddhartha Brahma, Selvum Pillay, Katherine
M. E. Stewart. Recycling of Polyethylene Terephthalate. SPE Annual Technical Conference
for Plastics Professionals (ANTEC), March 30 鈥� April 1, 2020, San Antonio, TX.
Siddhartha Brahma, Mahmoud Mohamed, Carlos Angulo, Haibin Ning, Selvum Pillay, Katherine
M. E. Stewart. Mechanical and Optical Characterization of Recycled Carbon Based Recycled
LDPE Composites. SPE Annual Technical Conference for Plastics Professionals (ANTEC),
March 30 鈥� April 1, 2020, San Antonio, TX.
Du H. Luu, Logan C. Ledbetter, Shaoyang Liu. Thermal Degradation of Polyethylene and
Polypropylene under Plastic Recycling Condition 鈥� a Study of Volatile Compound Profile.
The 52nd Annual Southeastern Undergraduate Research Conference. Tuscaloosa, AL, USA.
January 24-25, 2020.
2019 Presentations
G. Menon, K. M. E. Stewart and S. Pillay. Road-mapping Conference: Challenges of Plastics
Recycling. Plastics Recycling Conference and Trade Show. Washington D.C., USA. March
11, 2019.
Cookie Acknowledgment
This website uses cookies to collect information and to improve your browsing experience. Please review our privacy statement for more information.