Miscibility Of Poly Research Articles

Enhanced Impact Resistance, Oxygen Barrier, and Thermal Dimensional Stability of Biaxially Processed Miscible Poly(Lactic Acid)/Poly(Butylene Succinate) Thin Films.

This study investigates the crystallization, microstructure, and performance of poly(lactic acid)/poly(butylene succinate) (PLA/PBS) thin films processed through blown film extrusion and biaxial orientation (BO) at various blend ratios. Succinic anhydride (SA) was used to enhance interfacial adhesion in PLA-rich blends, while blends near 50/50 formed co-continuous phases without SA. Biaxial stretching and annealing, adjusted according to the crystallization behavior of PLA and PBS, significantly influenced crystallinity, crystallite size, and molecular orientation. Biaxial stretching induced crystallization and ordered chain alignment, particularly at the cold crystallization temperature (Tcc), leading to a 70-80-fold increase in impact resistance compared to blown films. Annealing further enhanced crystallinity, especially at the Tcc of PLA, resulting in larger crystallite sizes. BO films demonstrated reduced thermal shrinkage due to improved PLA crystalline structure, whereas PLA-rich blown films showed higher shrinkage due to PLA's lower thermal resistance. The SA-miscibilized phase reduced oxygen transmission in blown films, while BO films exhibited higher permeability due to anisotropic crystal orientation. However, the annealing of BO films, especially at high temperature (Tcc of PLA), further lowered oxygen permeability by promoting the crystallization of both PLA and PBS phases. Overall, the combination of SA compatibilization, biaxial stretching, and annealing resulted in substantial improvements in mechanical strength, dimensional stability, and oxygen barrier properties, highlighting the potential of these films for packaging applications.

Exploring the Electrochemical Performance of Molybdenum Disulfide Nanoparticles Entrenched in Miscible Poly(methyl methacrylate)-Poly(lactic acid) Blends as Freestanding Electrodes for Supercapacitors.

The focus of the study in this article is analyzing the electrochemical properties of molybdenum disulfide on miscible poly(methyl methacrylate)-poly(lactic acid) blends for supercapacitors. The interaction between molybdenum disulfide and miscible poly(methyl methacrylate)-poly(lactic acid) blends, affinity toward water, surface morphology, and mechanical properties are inspected by Fourier transform infrared spectroscopy, water contact angle, scanning electron microscopy, and universal testing machine, respectively. Among the developed membranes, 0.75 wt% of molybdenum disulfide on poly(methyl methacrylate)-poly(lactic acid) shows better electrochemical performances. It exhibits a maximum specific capacitance of 255.5 F g-1 at a current density of 1.00 mA g-1, maximum energy density of 22.7 Wh kg-1, and maximum power density of 360 W kg-1. A cycle study reveals 92% capacitance retention after 2500 cycles. The designed supercapacitor device shows a maximum specific capacitance of 1240 μF g-1 at a current density of 0.5 μA g-1, maximum energy density of 43 μWh kg-1, and maximum power density of 700 μW kg-1. Flexible membranes of molybdenum disulfide are expected to be a potent combination for supercapacitor applications.

Uniaxial stretching and properties of miscible poly(L-lactide)/poly(vinyl acetate) blends

Uniaxial stretching and properties of miscible poly(L-lactide)/poly(vinyl acetate) blends

Scalable Thermochromic Composite Based on a Ternary Polymer Blend for Temperature-Adaptive Solar Heat Management.

A scalable and durable thermochromic composite is developed for temperature-adaptive solar heat management using a carbon absorber and a thermoresponsive polymer blend consisting of an isolated polycaprolactone phase (PCL) and a continuous phase of miscible poly(methyl methacrylate) and polyvinylidene fluoride. The ternary blend exhibits reversible haze transition originating from the melting and crystallization of PCL. The refractive index matching between the molten PCL and surrounding miscible blend contributes to high-contrast haze switching in the range of 14-91% across the melting temperature of PCL (ca. 55 °C). The solar-absorption-switching properties of the composite are due to the spontaneous light-scattering switching in the polymer blend and the presence of a small amount of carbon black. Spectral measurements indicate that the solar reflectance of the composite sheet varies by 20% between 20 and 60 °C upon lamination with a Ag mirror. Solar heat management using the thermochromic composite is successfully demonstrated under natural sunlight, thereby realizing a temperature-adaptive thermal management system.

Study of Morphology, Rheology, and Dynamic Properties toward Unveiling the Partial Miscibility in Poly(lactic acid)-Poly(hydroxybutyrate-co-hydroxyvalerate) Blends.

The purpose of the present work was to gain a fundamental understanding of how the composition and physico-chemical properties affect the rheology, morphology, miscibility, and thermal stability of poly(lactic acid) (PLA)-poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) biopolymer blends obtained by melt mixing. First, restricted processing conditions were chosen, due to the inherent thermal degradation of PHBV, as proven by rheological dynamic time sweep (DTS) measurements and size-exclusion chromatography (SEC). Based on this, the composition dependence of the blends was investigated using small-amplitude oscillatory shear rheology (SAOS), and the results were confirmed by scanning electron microscopy (SEM) analysis. Subsequently, the changes in glass transition temperatures (Tgs) from the molten to the solid state, as observed by DMA and DSC, were verified by coupling SAOS to dielectric relaxation spectroscopy (DRS). Herein, the thermo-rheological complexity of PLA/PHBV blends in the melt was revealed, especially for PLA-rich blends. Irregularly structured morphologies, caused by highly mismatched viscoelastic properties, illustrated the degree of partial miscibility. Moreover, the thermo-rheological complexity appeared in the molten state of the asymmetric PLA-rich phases could be correlated to the crystal-amorphous interfacial MWS polarization, because of the locally-induced phase separation and heterogeneity, and owing to the differences in their crystallization properties during cooling. The miscibility also suffered from the lower thermal stability of PLA and the even more unstable PHBV. Nevertheless, the melt-induced degradation process of the PLA/PHBV blends seemed to be responsible for some of the in situ self-compatibilization and plasticization mechanisms. As a result, the miscibility and thermo-rheological simplicity were improved for the intermediate and PHBV-rich compositions at low temperatures, since their properties were, to a large extent, governed by the significant degradation of PHBV. The present findings should increase the understanding of morphological changes in PLA/PHBV blends and help control their micro/nanostructure.

Miscibility of Poly(lactide-co-glycolide) in Supercritical fluids

In a polymer based drug delivery system, the polymer material surrounds the drug and delivers the substance to the desired target. Poly(lactide-co-glycolide) (PLGA) is the most widely used control-release system for many drugs with a short half-life, low stability, easy decomposition, and non-toxic side effects. Supercritical fluid (SCF) technology can be used to prepare or micronize drug-loaded particles without additional purification or cleaning procedures. In this work, the liquid–liquid phase transition of PLGA in several supercritical fluids, such as dimethyl ether (DME), CO2, chlorodifluoromethane (HCFC-22), and trifluoromethane (HFC-23), has been investigated. PLGA with a higher content of glycolide in the copolymer backbone shows upper critical solution temperature (UCST)-type phase behavior. Alternatively, in supercritical HCFC-22, lower critical solution temperature (LCST)-type phase behavior has been observed. The ratio of lactide to glycolide in the PLGA copolymer backbone majorly controls the phase behavior including the pressure–temperature (p-T), temperature-polymer weight fraction (T-w), pressure-density (p-ρ), and temperature-density (T-ρ) isopleths. The phase behaviors of PLGA in SCF CO2 and DME change from UCST- to LCST-type behavior with an increase in the lactide content. In contrast, PLGA in SCF HCFC-22 exhibits LCST-type phase behavior for all PLGA copolymers irrespective of the lactide content. Such phase behaviors are described well by the perturbed-chain statistical associating fluid theory (PC-SAFT) in a wide range of temperature (300–395 K) and pressure (3–310 MPa) with temperature-independent binary interaction parameters. In addition, significant differences have been observed in the solubility of PLGA in different SCFs; CO2 being the poorest solvent, and HCFC-22 being the best solvent.

In Situ Chemical Modification of Thermoplastic Starch with Poly(L-lactide) and Poly(butylene succinate) for an Effectively Miscible Ternary Blend

Thermoplastic starch (TPS) is in situ ring-opening polymerized with L-lactide (L-LA) and directly condensed with a poly(butylene succinate) (PBS) prepolymer in an extruder using two different production pathways to demonstrate the concept “like dissolves like” in a miscible poly(lactide)/TPS/PBS (PLA/TPS/PBS) ternary blend. The TPS crystalline pattern changes from a VH-type to an EH-type after TPS modification with a hydrophobic-PLLA segment. Heteronuclear multiple-bond correlation confirmed the successful formation of PLLA-TPS-PBS copolymers via two different in situ chemical modification pathways (i.e., (I) step-by-step modification and (II) one-pot reaction). All obtained PLLA-TPS-PBS copolymers functioned as the miscible phase, enhancing PLA/PLLA-TPS-PBS/PBS ternary blend miscibility, especially the random structural PLLA-TPS-PBS-II copolymers created in an in situ one-pot reaction. However, the PLLA-TPS-PBS-I copolymers can enhance PBS crystallization only. While the random PLLA-TPS-PBS-II copolymers exhibit a homogeneous multi-phase dispersion and crystallization acceleration in both the PLA and PBS chains. Moreover, the storage modulus level of the PLA/PLLA-TPS-PBS-II/PBS ternary blend remains high with a downward temperature shift in the glass transition region, indicating a stronger and more flexible system. The practical achievement of in situ modified TPS and, consequently, a miscible PLA/PLLA-TPS-PBS/PBS ternary blend with favorable physical properties, reveal its potential application in both compostable and food contact packaging.

Miscibility and thermal behavior of poly(methyl methacrylate) and polystyrene blend using benzene as a common solvent.

Polymer blending is one of the advanced technologies to attain polymeric material with tailored properties. In this work, the miscibility of Poly(methyl methacrylate) (PMMA) and Polystyrene (PS) blend in benzene was investigated by employing various techniques such as FTIR spectroscopy, viscosity measurement technique, light scattering techniques, DSC and TGA techniques over an extended range of concentrations, compositions, and temperatures. The results revealed that there exist hydrogen bonding and hydrodynamic interactions which led these polymers to get miscible to a large extent. The compatibility increased with the increasing PS contents or increase in temperature of the system. In addition, the thermal stability of blends was found to be improved with the increase in the compatibility of the polymer.

Mechano‐opticalbehavior in poly (ethylene terephthalate)/poly (ether imide) blends

AbstractMechano‐optical behavior and related structural evolution during uniaxial stretching of melt miscible poly (ethylene terephthalate) (PET)/poly (ether imide) (PEI) blends were studied near their glass transition temperature using an instrumented machine that measures true stress, true strain and spectral birefringence simultaneously. Stretching from amorphous state, two distinct stress‐optical regimes were observed at temperatures between Tgand Tcc(cold crystallization). Near Tg, a typical photoelastic behavior persists until a critical temperature above which temperature independent initial stress optical behavior is observed. At those temperatures above Tg, where glassy behavior is observed, decreasing stretching rate was also found to eliminate this glassy photo elastic regime leading to the observation of a linear initial stress optical behavior that becomes temperature independent as expected from linear stress optical rule. Increasing PEI concentration in the blends suppresses crystallizability and increases temperature at which initial elastic region disappears giving way to pure liquid behavior where linear stress optical behavior is observed. This is attributed to the increase and broadening of the glass transition temperature with the addition of noncrystallizable PEI. In PET/PEI blends, the stress‐optical coefficient (SOC), determined in a linear stress optical regime, was found to increase linearly with the increase in PEI concentration.

Mixing of Racemic Poly(L-lactide)/Poly(D-lactide) Blend with Miscible Poly(D,L-lactide): Toward All Stereocomplex-type Polylactide with Strikingly Enhanced SC Crystallizability

Mixing of Racemic Poly(L-lactide)/Poly(D-lactide) Blend with Miscible Poly(D,L-lactide): Toward All Stereocomplex-type Polylactide with Strikingly Enhanced SC Crystallizability

Miscibility of poly(urethane-urea) elastomers with chlorinated poly(vinyl chloride)

Effect of a chemical structure of poly(ether-urethane-urea) (PUU) elastomers on a miscibility of their blends with chlorinated poly(vinyl chloride) (cPVC) has been studied by FTIR and DSC. The segmented PUU were synthesized by prepolymer approach in N,N-dimethylformamide (DMF) solution. PUU-1 was synthesized using poly(propylene glycol) (PPG) of Mn = 1000, mixture of 2,4- and 2,6-isomers of tolylenediisocyanate (TDI) in a ratio of 65:35 (by weight) and 4,4´-methylenedianiline as a chain extender at a molar ratio of 1:2:1. PUU-2 was prepared based on poly(tetramethylene glycol) (PTMG) of Mn = 1000, TDI and cyanoethylated ethylene diamine at a molar ratio of 2:3:1. The polymer-polymer blends were obtained via solution casting technique using DMF as a solvent. It was found a miscibility of the polymers enhances due to a formation of hydrogen or donor-acceptor bonding between polar NH urethane-urea or nitrile groups of hard PUU segments and chlorine of cPVC. According to DSC results the polymer-polymer systems stabilized by stronger donor-acceptor bonding are characterized by single glass transition temperature, Tg, a position of which is higher than that of the theoretical one, TFg, calculated in full composition range via Fox’s equation. When stabilization of polymer-polymer blend with 30 % (by weight) of cPVC performs by weaker hydrogen bonding we observed a formation of mixed phase and the composite is characterized by appearance of three relaxation transitions. Increasing cPVC content reduces a miscibility of the components and biphasic structure of the composites forms. Comparative analysis of experimental and theoretical (additive) tensile strength vs composition dependencies demonstrates an impact of donor-acceptor interface interactions on strength of the polymer composites obtained.

Robust electromagnetic interference shielding, joule heating, thermal conductivity, and anti-dripping performances of polyoxymethylene with uniform distribution and high content of carbon-based nanofillers

Fabrication of high-performance and multiple-function conductive polymer composites with uniform distribution and high content of carbon-based nanofillers has been a formidable challenge. In this study, a new strategy was introduced to fabricate polyoxymethylene (POM)/multi-walled carbon nanotube (MWCNT) and POM/graphene nanoplate (GNP) composites (PMCNT and PMGNP, respectively), with uniform distributions and high contents of MWCNT and GNP, by assisting of miscible poly(l-lactide) (PLLA). As expected, the composites exhibit robust electromagnetic interference (EMI) shielding, Joule heating, thermal conductivity, and anti-dripping performance. Specifically, the EMI shielding effectiveness of PMCNT40 (with 40 wt% MWCNT) and PMGNP48 (with 48 wt% GNP) reached 45.7 and 44.7 dB with 0.15 mm in thickness. The high electrical and through plane thermal conductivities were 3484 S/m and 1.95 Wm−1K−1, respectively, for PMCNT40, and the corresponding values for PMGNP48 were 2695 S/m and 4.24 Wm−1K−1, respectively. Furthermore, the fabricated composites achieved excellent Joule heating performance, resulting in increases in surface temperature increase to 101.4 °C and 107.6 °C rapidly at the driving voltages of 3.0 V (in case of PMCNT40) and 6.0 V (in case of PMGNP48), respectively. In addition, the composites exhibited excellent solvent resistance and anti-dripping performance, indicating high potential applicability in extreme environments.

Miscibility of Poly(Methyl Methacrylate) and Poly(Vinylidene Fluoride) Examined by Thermally Stimulated Depolarization Current and Dielectric Relaxation Spectroscopy

Samples of poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVDF) and melt blended PMMA/PVDF with weight ratios 4/1 and 3/2 were characterized by thermally stimulated depolarization currents (TSDC) in the temperature interval 123-303 K and by dielectric relaxation spectroscopy (DRS) in the frequency window 10−2 − 106 Hz in the temperature interval 153-423 K. The TSDC thermograms and DRS profiles of the samples showed the two types of conducnivity – non-cooperative and cooperative. The experimental DRS data in the vicinity of the glass transition temperature, Tg, were quantitatively fitted to the Havriliak-Negami function and values of the maximum relaxation time were fitted to the Vogel-Tammann-Fulcher equation. Higher values of the strength index D, of the dielectric relaxation strength Δε and of the σ ac conductivity for the binary blends were considered as experimental evidence for nanoscale composition heterogeneities originating from strong specific interactions between the PMMA and PVDF. Therefore, we suggest the PMMA/PVDF blends will be usefull as effective materials for the manufacture of lithium-ion batteries, electrostatic capacitors with superior energy storage performance, polymer composite electrolytes for solar cells, etc.

The effect of short polystyrene brushes grafted from graphene oxide on the behavior of miscible PMMA/SAN blends

A new concept of utilization of particle-polymer hybrids as multifunctional additives for polymer blends was introduced in this study. Graphene oxide particles with short densely grafted polystyrene brushes (GO-g-PS) were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP). Melt rheology studies revealed that GO-g-PS suppressed the phase separation of miscible poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) (PMMA/SAN) blends. The studies suggested specific interactions of GO-g-PS with the PMMA phase and this was confirmed based on calculations of activation energies of segmental relaxations by broadband dielectric spectroscopy (BDS). These unusual interactions of GO-g-PS with PMMA phase were assigned to the specific and precise architecture of the GO-g-PS particles as well as chemical nature of PS polymer brushes. The short chains of PMMA and PS provide miscibility originating from UCST behavior of PMMA/PS blend of short polymer chains. Additionally, BDS also revealed improved charge transport in PMMA/SAN blend in presence of GO-g-PS hybrid.

Low-temperature sintering of stereocomplex-type polylactide nascent powder: The role of poly(methyl methacrylate) in tailoring the interfacial crystallization between powder particles

Despite of its enormous application potential as a prominent engineering bioplastic, the processing of the stereocomplex-type polylactide (SC-PLA) formed from poly(l-lactide)/poly(d-lactide) (PLLA/PDLA) blends into useful products remains challenging. Recently, low-temperature sintering has emerged as a feasible and promising processing technology towards transparent highly-crystalline SC-PLA products. During the sintering of SC-PLA nascent powder, the interfaces between adjacent particles could be bound together through SC crystallization of interdiffused PLLA and PDLA chains across the interfaces. However, the massive generation of the interface-localized SC crystallites is significantly impaired by the insufficient chain interdiffusion resulting from the rapid SC crystallization. In this work, miscible poly(methyl methacrylate) (PMMA) is adopted to substantially promote the chain interdiffusion by fundamentally diminishing the SC crystallization rate. Intriguingly, we find that the crystallization of PLLA/PDLA chains is greatly decelerated with the incorporation of PMMA and thus more enantiomeric PLA chains could interdiffuse through the interfaces before their crystallization. Moreover, the PMMA is also favorable for the particle wetting of the densified nascent powders, which makes it easier for the enantiomeric chains to interdiffuse across the interfaces. The promoted chain interdiffusion leads to an evident increase in the number of the newly-generated SC crystallites and resulting interfacial weld strength. Consequently, the sintered SC-PLA products possessing superior thermomechanical properties and markedly enhanced hydrolytic resistance have been fabricated by incorporating 9 wt% PMMA, without compromising transparency. These findings could bode well for the industrial fabrication and applications of SC-PLA products.

Enhanced thermal, mechanical and electromagnetic interference shielding properties of graphene nanoplatelets-reinforced poly(lactic acid)/poly(ethylene oxide) nanocomposites

Graphene nanoplatelets (GNPs) were studied as a novel nanofiller of miscible poly(lactic acid) (PLA)/poly(ethylene oxide) (PEO) blend matrix. The adding level of GNPs varied from 0 to 15 wt%. PLA was blended with PEO to enhance its flexibility, while further incorporation of GNPs was aimed at improving the rigidity, thermal stability and electromagnetic interference (EMI) shielding properties of PLA/PEO blends. Rheological results and scanning electron micrographs revealed that a percolating 3-dimesional network within the PLA/PEO matrix was formed when the GNPs content above 6 wt%. The addition of 15 wt% GNPs into PLA/PEO matrix led to an increase of 247 % and 83 % in tensile modulus and strength, respectively, while the elongation at break was still at an acceptable value of 82.1 %. Moreover, the initial degradation temperature (Td5) increased by 31.9 °C. In addition, the incorporation of GNPs enhanced significantly the EMI shielding effectiveness (SE) of PLA/PEO blend matrix. Compared with PLA/PEO nanocomposites with 6 wt% GNPs, further addition of 1 wt% carbon nanotubes (CNTs) improved remarkably the thermal, mechanical, electricity and EMI SE of the materials. The effect of PEO and nanofillers on the crystallization behavior of PLA was also addressed.

Organic solvent-free fabrication of mesoporous polymer monolith from miscible PLLA/PMMA blend

The fabrication of monoliths by environment-friendly methods without organic solvents remains a challenging task. In this study, we successfully produced mesoporous polymer monoliths by selective hydrolysis degradation of miscible poly(-L-lactic acid) (PLLA)/poly(methyl methacrylate) (PMMA) blends without any organic solvents. 50 to 90 wt% of PLLA blend ratios were tested. We found that freeze-dried was effective to prevent a shrinkage of monoliths. With increaser of PLLA weight fraction, porosity, mode pore diameter, and pore geometry could be controlled from 17 to 52%, 7.1–32 nm, and mainly cylindrical to spherical, respectively. Further, a comprehensive model based on volume balance and surface area equivalence successfully predicted mode pore size. The reported organic solvent-free fabrication of mesoporous polymer monoliths might enable tunable mesopore properties through only changing mechanical blending of miscible polymers.

High Lithium Conductivity of Miscible Poly(ethylene oxide)/Methacrylic Sulfonamide Anionic Polyelectrolyte Polymer Blends

In this work, we develop novel single-ion polymer electrolytes by mixing poly(lithium 1-[3-(methacryloyloxy) propylsulfonyl]-1-(trifluoromethanesulfonyl) imide) (PLiMTFSI) and poly(ethylene oxide) ...

Facile Preparation of Electromagnetic Interference Shielding Materials Enabled by Constructing Interconnected Network of Multi-walled Carbon Nanotubes in a Miscible Polymeric Blend

Electromagnetic interference (EMI) shielding materials are in great demand in electronic equipment and our surrounding environment to resist the increasing serious radiation pollution. Compared with their metal counterparts, conductive polymer composites (CPCs) have unique advantages of lightweight, corrosive resistance, low cost, and excellent processability, and are therefore an ideal choice for developing high-performance EMI shielding materials. However, CPCs based EMI shielding materials are limited to high filler loading, which caused poor mechanical properties and processability. Here, we demonstrate a facile and highly scalable approach to develop high-performance EMI shielding materials with low filler loading by using miscible poly(phenylene oxide)/polystyrene (PPO/PS) blend as the matrix. In contrast to PS/carbon nanotubes (CNTs) composites, PPO/PS/CNTs composites show much higher EMI shielding effectiveness caused by good dispersion of CNTs and highly interconnected conductive network. An excellent EMI shieling effectiveness of 23–25 dB is achieved for PPO/PS/10%CNTs composites with a thickness of only 375 µm, which is superior to most of reported polymer/CNTs composites prepared by melt-compounding. In addition, the results show that although absorption is the major shielding mechanism, the contribution of reflection is also important and closely related to the connectivity of conductive network, as well as the electrical conductivity of the CPCs.

Enhanced thermal stability, toughness, and electrical conductivity of carbon nanotube-reinforced biodegradable poly(lactic acid)/poly(ethylene oxide) blend-based nanocomposites

Carbon nanotube (CNT) was incorporated into the miscible poly(lactic acid)/poly(ethylene oxide) (PLA/PEO) blend to successfully fabricate biodegradable nanocomposites. Scanning electron microscope images revealed the well dispersion of as-received CNT within the blend through the melt-mixing process. Thermogravimetric analysis showed that the CNT significantly improved the thermal stability of the blend (up to 68 °C increase at 3-phr CNT addition compared to the blend at 10 wt% loss) in air. Differential scanning calorimetry data showed the nucleation effect of CNT on the crystallization of individual PLA and PEO; the presence of CNT increased the melting temperature of PLA crystals. Measurement of rheological behavior confirmed the formation of CNT (pseudo-)network structure in the composites. The impact strength of the composite with 3-phr CNT loading was three times higher than that of the blend. The electrical resistivity of the blend reduced by up to nine orders of magnitude at 3-phr CNT loading. The electrical and rheological percolation thresholds were both achieved at 1-phr CNT loading for the nanocomposites.