Materials,
Год журнала:
2024,
Номер
18(1), С. 36 - 36
Опубликована: Дек. 25, 2024
This
research
explores
how
varying
proportions
of
virgin
polyethylene
terephthalate
(vPET)
and
recycled
(rPET)
in
vPET-rPET
blends,
combined
with
preform
thermal
conditions
during
the
stretch
blow
molding
(SBM)
process,
influence
PET
bottles’
microscopic
characteristics.
Key
metrics
such
as
viscosity,
density,
crystallinity,
amorphous
phase
relaxation,
microcavitation
were
assessed
using
response
surface
methodology
(RSM).
Statistical
analysis,
including
Analysis
variance
(ANOVA)
its
power,
supported
interpretation
results.
The
first
part
work
details
experimental
design
statistical
methods.
Positron
annihilation
lifetime
spectroscopy
(PALS)
density
analysis
revealed
reduced
free
volume
size,
a
substantial
increase
quantity,
transformation
toward
ellipsoidal
geometries,
highlighting
significant
structural
changes
material.
At
same
time,
intrinsic
viscosity
(IV)
PALS
studies
indicate
that
solid-state
post-condensation
effect
(SSPC)
is
linked
through
product
diffusion.
conclusions,
which
resulted
from
microstructure
affected
material’s
mechanical
strength
validated
by
pressure
resistance
tests
bottles.
Polymers,
Год журнала:
2025,
Номер
17(6), С. 820 - 820
Опубликована: Март 20, 2025
Recycling
and
reutilization
of
waste
PET
through
alcoholysis
has
been
a
prominent
focus
current
research.
However,
the
process
is
reversible,
leading
to
generation
oligomeric
byproducts.
To
further
utilize
these
wastes,
this
paper
processed
derived
from
various
systems
synthesize
unsaturated
polyester
resins
(UPRs).
The
fundamental
characteristics,
mechanical
properties,
curing
processes
synthesized
UPRs
were
analyzed
based
on
GPC,
FTIR,
TG,
tensile
testing,
DMA,
DSC
tests.
results
indicate
that
wastes
successfully
UPRs.
ethylene
glycol
(EG)
diethylene
(DEG)
possess
more
complex
compositions;
among
these,
UPR
EG
exhibited
higher
thermal
stability,
whereas
DEG
showed
broader
molecular
weight
distribution
lower
glass
transition
temperature
(Tg).
In
addition,
remarkably
high
elongation
at
break
(>180%),
potentially
attributed
its
long
chains.
Regarding
obtained
propylene
(PG)
slower
rates
demanded
activation
energies.
Moreover,
could
be
well
described
by
Sesták–Berggren
autocatalytic
model.
Scientific Reports,
Год журнала:
2025,
Номер
15(1)
Опубликована: Март 24, 2025
Abstract
Recycled
polyethylene
terephthalate
(RPET)
was
doped
with
Neodymium
Oxide
(Nd
2
O
3
:
0,
1,
2,
4,
and
8
wt.%)
to
investigate
its
structural,
optical,
dielectric,
mechanical
properties.
X-ray
diffraction
(XRD)
analysis
revealed
that
pure
RPET
exhibited
an
amorphous
structure,
while
the
incorporation
ofNd
induced
formation
of
crystalline
phases,
crystallinity
increasing
as
Nd
concentration
increased.
Fourier-transform
infrared
(FTIR)
spectroscopy
identified
chemical
interactions
between
,
evidenced
by
a
new
band
around
535
cm
−1
.
Optical
using
diffuse
reflectance
UV–Vis
showed
reduction
in
gap
from
3.75
eV
for
2.25
8wt.%
samples,
indicating
enhanced
optical
Dielectric
studies
doping
significantly
decreased
dielectric
constant
RPET,
contributing
thermal
stability
constant.
Furthermore,
loss
conductivity
improved,
observed
across
varying
temperatures.
Dynamic
(DMA)
adding
wt.%
reduced
storage
modulus
1.62
GPa
approximately
0.26
at
35
°C,
attributed
structural
softening.
These
improvements
suggest
-doped
is
suitable
applications
requiring
conductive
REPT,
low
modulus,
stability,
energy
dissipation
capabilities.
Environments,
Год журнала:
2025,
Номер
12(4), С. 127 - 127
Опубликована: Апрель 18, 2025
Waste
polyethylene
terephthalate
(PET)
bottles
represent
12%
of
global
plastic
waste;
however,
only
9%
are
recycled.
Hydrothermal
processing
presents
the
opportunity
to
upcycle
waste
PET
into
its
monomers,
particularly,
terephthalic
acid
(TPA).
In
this
study,
post-consumer
sparkling
water
were
neutrally
hydrolysed
via
a
hydrothermal
process
operating
within
temperature
range
220–270
°C,
residence
time
30–90
min,
and
autogenous
pressure
25–90
bar.
Under
these
conditions,
TPA
yield
varied
between
7.34
81.05%,
maximum
was
obtained
at
250
90
40
The
had
more
profound
impact
on
conversion
than
time.
values
environmental
factor
(EF)
found
be
0.017–0.106,
which
comparable
those
bulk
chemicals
(EF
<
1).
With
chosen
energy
(EEI)
production
estimated
5.29
×
104
°C
min.
findings
demonstrate
that
neutral
hydrolysis
is
feasible
approach
for
converting
polymers
monomers
under
mild
conditions.
addition,
GCMS
analysis
aqueous-phase
product
revealed
notable
increase
in
secondary
degradation
products
TPA,
such
as
benzoic
acid,
rising
from
66.4%
75.7%
increased
220
270
°C.
mechanisms
decarboxylation,
dehydration,
oxidation.
dominant
mechanism
decarboxylation
reaction.
Materials,
Год журнала:
2024,
Номер
17(21), С. 5233 - 5233
Опубликована: Окт. 27, 2024
Polyethylene
terephthalate
(PET)
is
widely
used
in
bottle
production
due
to
its
cost-effectiveness
and
low
environmental
impact.
The
first
part
of
this
article
describes
the
research
statistical
analysis
methodology
influence
virgin
PET
(vPET)
recycled
(rPET)
content
vPET-rPET
blend,
as
well
preform
heating/cooling
conditions
stretch
blow
molding
(SBM)
process
on
microscopic
properties.
Microscopic
properties
such
crystallinity,
density,
viscosity,
relaxation
degree
amorphous
phase,
microcavitation
were
examined.
This
study
reveals
that
microcavity
solid-state
post-condensation
effects
occur
during
deformation
SBM
process.
increase
free
volume,
indicating
microcavitation,
was
confirmed
by
measuring
positron
annihilation
lifetime
spectroscopy
(PALS).
PALS
density
phase
studies
prove
a
reduction
dimensions
volumes,
with
simultaneous
significant
their
number
ellipsoidization.
It
can
be
associated
crystallite
rotation
temperature-dependent
non-crystalline
matrix.
occurrence
intrinsic
viscosity.
conclusions
resulting
from
microstructure
affecting
mechanical
strength
material
validated
pressure
resistance
tests
bottles.
