Journal of Applied Polymer Science,
Journal Year:
2024,
Volume and Issue:
141(44)
Published: Aug. 20, 2024
Abstract
In
order
to
clarify
the
effect
of
feeding
rate
ratio
(Rsr)
for
polylactic
acid
(PLA)
polyethylene
glycol
(PEG)
on
performance
thermal
regulation
nanofibers,
PLA
and
PEG
solutions
were
used
as
outer
inner
spinning
solutions,
respectively,
develop
PLA/PEG
nanofibers
(NFp‐p)
through
coaxial
electrospinning.
NFp‐p
with
Rsr
2:1,
3:1,
4:1
labeled
PR
1
,
2
3
respectively.
The
morphology,
chemical
structure,
mechanical
properties,
tested,
function
was
investigated.
results
showed
that
increasing
could
increase
diameter
NFp‐p,
having
smallest
average
(520
nm).
had
lowest
water
contact
angle
(122.4°),
higher
enhanced
encapsulation
PEG.
properties
significantly
improved
compared
pure
PLA,
exhibiting
highest
breaking
stress
(2.5
MPa)
strain
(213%).
be
regulated
by
Rsr,
showing
a
more
pronounced
endothermic
peak
due
melting
PEG,
phase‐change
enthalpy
(13.2
J/g).
Lower
superior
performance.
ACS Applied Polymer Materials,
Journal Year:
2024,
Volume and Issue:
6(3), P. 1962 - 1972
Published: Jan. 26, 2024
Silicon-containing
arylacetylene
resins
(PSAs)
are
widely
used
as
heat-resistant
resin
matrices
in
aerospace
and
electronic
information
technology.
In
this
paper,
the
thermal
oxidation
behavior
its
mechanism
for
cured
poly(diethynylbenzene-dimethylsilylene-3,6-diethynylcarbazole)
(DEC-DMS)
were
investigated
via
experiments
simulations.
The
macroscopic
kinetics
of
DEC-DMS
studied
thermogravimetric
analysis
(TGA),
reaction
steps
analyzed
mathematical
deconvolution.
structural
changes
residues
formed
at
different
temperatures
characterized
by
Fourier
transform
infrared
(FTIR)
X-ray
photoelectron
spectroscopy
(XPS).
composition
volatile
products
generated
during
was
detected
online
thermogravimetry-Fourier
(TG-FTIR).
simulated
reactive
force
field
molecular
dynamics
(ReaxFF-MD),
possible
pathways
matter
production
analyzed.
results
showed
that
involved
three
steps:
(1)
weight
gain
unsaturated
bonds,
(2)
oxidative
cleavage
side
chain
groups,
(3)
degradation
cross-links
aromatic
rings.
included
CO,
CO2,
CH4,
H2O.
provide
theoretical
guidance
development
PSAs
resistant
to
oxidation.
Carbon Resources Conversion,
Journal Year:
2024,
Volume and Issue:
7(3), P. 100226 - 100226
Published: Jan. 26, 2024
The
lignocellulose
reinforced
composites
are
commonly
used
sustainable
materials
with
good
mechanical
and
physical
properties.
Aiming
to
properly
dispose
recover
the
potential
value
of
discarded
composites,
pyrolysis
behaviour
kinetics
reed
straw
processing
residual/polylactic
acid
(RSPR/PLA)
a
typical
3D
printing
material,
was
investigated.
Based
on
TG-FTIR
results,
synergistic
effects
between
RSPR
PLA
during
process
were
clarified.
Compared
FTIR
spectra
PLA,
absorption
peaks
CO
CO2
disappear
in
RSPR/PLA
composite,
which
indicates
provides
additional
free
radicals
for
radical
reaction
further
promoting
decomposition.
apparent
activation
energy
composite
calculated
by
two
iso-conversional
methods
including
Flynn-Wall-Ozawa
(FWO)
Kissinger-Akahira-Sunose
(KAS).
average
Ea
(122.6
kJ
mol-1
117.9
(KAS))
lower
than
that
solo
(138.5
135.4
pure
(197.0
196.6
(KAS)).
master
plot
method
results
suggested
followed
one-dimensional
(D1)
diffusion
model.
This
work
an
environmentally
friendly
strategy
effective
thermo-chemical
upgrading
material.
Macromolecules,
Journal Year:
2023,
Volume and Issue:
56(19), P. 7749 - 7762
Published: Sept. 18, 2023
As
an
important
polymer
in
conventional
applications,
the
service
stability
and
biodegradability
of
poly(butylene
adipate-co-terephthalate)
(PBAT)
have
been
well
explored.
However,
CO2
production
mechanism
during
photo-oxidation
process
remains
unclear.
Herein,
pathways
photo-oxidative
degradation
PBAT
were
investigated
via
calculations
experiments.
A
simulation
strategy
was
established
based
on
time-dependent
density
functional
theory,
results
show
that
ultraviolet
(UV)
radiation
promotes
decarboxylation
terephthalate)
under
oxygen-free
conditions,
along
with
oxidation
decomposition
adipate)
segments
oxygen-rich
conditions.
Hole–electron
analysis
indicates
UV
alters
bonding
states,
lowering
energy
barriers
for
key
reactions.
In
situ
Fourier
transform
infrared
spectroscopy
outdoor
aging
experiments
substantiate
calculation
results.
Hence,
this
work
sheds
light
behavior
PBAT,
enhancing
our
understanding
its
application
potential.
Polymer Degradation and Stability,
Journal Year:
2023,
Volume and Issue:
217, P. 110536 - 110536
Published: Sept. 13, 2023
It
is
well
known
that
polyethylene
(PE)
generates
CO2
during
photo-oxidative
aging;
however,
there
still
some
ambiguity
in
the
exact
mechanistic
steps
involved.
In
this
work,
aging
mechanism
of
PE
considered
via
quantum
chemical
(QC)
calculations.
This
demonstrates
it
difficult
for
previously
proposed
Norrish
I
mechanisms
to
occur
because
high
energy
required
and
forbidden
transitions.
A
synergistic
effect
between
oxygen
ultraviolet
(UV)
radiation
shown
promote
initiation
aging,
providing
a
more
reasonable
description
photo-oxidation
than
existing
mechanisms.
The
charge
differential
density
(CDD)
indicates
UV
alters
electron
distribution
so
transfer
from
secondary
C-H
bond
H-OO
promotes
formation
HOO·.
As
established,
after
reaction,
formed
radical
converted
into
hydroperoxide.
conversion
hydroperoxide
ketones
cleavage
O-OH
bonds
hydroxyl
radicals.
radicals
can
further
react
with
ketonic
carbonyls,
resulting
carbonic
acid.
Finally,
acid
decomposes
CO2.
difference
crystalline
amorphous
phases
was
studied
by
molecular
dynamics
(MD)
simulation.
MD
results
show
phase
photo-oxidize
poorer
permeation
ability
solubility
but
not
diffusion
O2.
