Thermal Stability Of Poly Research Articles

Influence of Acetylated Cellulose Nanocrystal Incorporated into Poly(e-Caprolactone) Nanocomposites on Its Thermal, Mechanical, and Physicochemical Properties

Poly(e-caprolactone) are synthetic biodegradable polymers that can potentially be used as biocompatible materials for biological applications. The purpose of this work was to investigate the effect of acetylated cellulose nanocrystals isolated from corncob waste loaded into poly(e-caprolactone) matrix blend on its thermal, mechanical, morphology, and crystallinity. The acetylated cellulose nanocrystal filler with various concentrations (namely 5, 10, 15, and 20%) was mixed with poly(e-caprolactone) matrix prepared using reflux method under N2 gas flow at 120oC for 10 min. Subsequently, the samples was characterized by thermal gravimetric analysis, DSC, tensile, Fourier transform infrared spectroscopy, tunneling electron microscope, SEM, and XRD to determine the thermal, mechanical, functional group, particle size, morphology, and crystallinity, respectively. Thermal gravimetric analysis and DSC analysis revealed that the thermal stability of poly(e-caprolactone) improved and the degree of crystallinity gradually increased with the addition of 10% acetylated cellulose nanocrystals, hence resulting in a higher Young's modulus. Fourier transform infrared spectroscopy results demonstrate that acetylated cellulose nanocrystal was successfully incorporated into poly(e-caprolactone) with an additional OH group. In addition, the particle size of 32 nm for acetylated cellulose nanocrystal and the formation of agglomeration was present based on TEM analysis, thus suggesting that acetylated cellulose nanocrystal was compatible as a reinforcing filler in the poly(e-caprolactone) matrix. SEM and XRD analysis suggests that the morphology was relatively smooth and higher crystallinity was achieved. The results of this research demonstrated the good feasibility of poly(e-caprolactone)/acetylated cellulose nanocrystal nanocomposites with improved thermal, mechanical, and physicochemical properties that were successfully prepared using simple and low-cost acetylated cellulose nanocrystal as a filler material.

Synergistic effects of graphene nanoplatelets on X-band electromagnetic interference shielding, thermal expansion and thermal stability of poly(ether-ketone) based nanocomposites

In this work, the electromagnetic interference shielding effectiveness (EMI-SE) of the poly(ether-ketone) (PEK)-graphene nanoplatelets (GNP) nanocomposites fabricated by planetary ball mill followed by hot pressing were investigated in X-band (8.2–12.4 GHz). A percolation threshold of about 0.4 vol% GNP was obtained. The electrical conductivity was increased to about 0.02 S/cm with an EMI-SE of ~33 dB for 1 mm thick 5 vol% GNP filled PEK nanocomposite. This higher value is corresponding to more than 99.95% blocking of the EMI. The EMI-SE increases with increasing thickness of the nanocomposite. The thermal stability and the char yield of the nanocomposites reinforced with 5 vol% GNP were found to increase to 570 °C and to 61.6%, respectively. The dimensional stability of the nanocomposites was also increased compared to neat PEK.

Polyphosphates as thermal stabilizers for poly(vinyl chloride)

Polyphosphates had been used as thermal stabilizers for polyvinylchloride (PVC). The thermal stability of PVC films stabilized with polyphosphates was verified by using weight loss method, Fourier transform infrared (FTIR) spectroscopy, thermal aging test, optical microscope and atomic force microscope. The outcomes demonstrated that mixing of polyphosphates with PVC can obviously enhance the stability time of PVC and improve the initial color of it. Furthermore, polyphosphates could considerably decrease the concentrations of forming double bonds within the PVC chemical structure and decrease weight loss. In addition, polyphosphate has an excellent ability to reduce the releasing of hydrochloric acid (HCl) molecules. Hence polyphosphates can replace the labile chlorine atoms within the chemical structure of PVC chains.

Effect of Nonionic Surfactants on the Crystallinity and Thermal Stability of Poly(vinyl alcohol) Film

In this study, poly(vinyl alcohol) (PVA)/surfactant films were prepared by casting technique. Two nonionic surfactants with different alkyl chain lenghts (Tween 20 and Tween 40) were used. PVA/Tween 20 and PVA/Tween 40 films were characterized by means of Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). FTIR spectra of PVA/Tween films indicated the presence of hydrogen bond interactions between the Tween surfactants and PVA. XRD results showed that the incorporation of Tween 20 and 40 into the PVA film decreased the crystallinity of PVA.TGA curves revealed an increase in the thermal stability of PVA film in the presence of the surfactants. DOI: http://dx.doi.org/10.17807/orbital.v12i4.1514

Facile preparation of a high-transparency anti-fogging/frost-resisting poly(AMPS-co-AA) coating with self-healing property

Hydrophilic anti-fogging coatings have been applied in various aspects of life. In this work, a hydrophilic anti-fogging and frost-resisting coating which also exhibited self-healing property was prepared by 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and acrylic acid (AA). The coating possessed high transmittance in aggressive fogging conditions compared with bare glass, owing to its hydrophilic property. The behavior of water droplets on the poly(AMPS-co-AA) and polymer AMPS (PAMPS) coatings were observed, it could be found that the PAMPS coating tended to aggregate under the same fogging conditions. The fact was further confirmed by UV–vis-NIR analysis, the PAMPS coating enjoyed a lower UV–vis-NIR transmittance value than the poly(AMPS-co-AA) coating because of its aggregation after anti-fogging experiment. From the TG analysis, we also could conclude that the thermal stability of poly(AMPS-co-AA) coating was better than PAMPS coating. Contact Angle Analyzer, 1HNMR, ATR-FTIR, SEM, and AFM were also used to describe the composition, structure, and characterization of the coating.

Magnetic, electrical and gas sensing properties of poly(o-phenylenediamine)/MnCoFe2O4 nanocomposites

A series of poly(o-phenylenediamine)/MnCoFe2O4 nanocomposites containing varying concentrations of MnCoFe2O4 were synthesized by in situ oxidative polymerization method. These nanocomposites were characterized by thermal, spectroscopic, microscopic techniques and dielectric properties analyzed at different temperature and frequency. X-ray diffraction and Fourier-transform infrared spectra are confirming the formation of poly(o-phenylenediamine)/MnCoFe2O4 nanocomposites. The Mossbauer spectral data are indicating the inverse nature of MnCoFe2O4 nanoparticles. The ferromagnetic behavior of nanocomposites is ascertained with the hysteresis loops of MnCoFe2O4. Transmission electron microscopy results are giving good evidences for the deposition of MnCoFe2O4 nanoparticles on the poly(o-phenylenediamine) matrix and the modification of spherical morphology of poly(o-phenylenediamine) by MnCoFe2O4. The thermal stability of poly(o-phenylenediamine)/MnCoFe2O4 nanocomposites is increasing with increase in the concentration of MnCoFe2O4 nanoparticles. Dielectric constant and AC conductivity of nanocomposites are varying with applied frequency, temperature and concentration of MnCoFe2O4 nanoparticles. The ethanol gas sensing ability of MnCoFe2O4 has been improved by poly(o-phenylenediamine) matrix.

Thermal Stability of Poly (2 - Acrylamido -4- Antipyrinyl) Thiazole Homopolymer and Copolymer of 2- Acrylamido -4- Antipyrinyl Thiazole with Methyl Methacyylate (Dept.p)

Different concentrations of copolymer of (2-acrylamido-4-antipyrinyl) thiazole with methyl methacrylate were prepared and the reactivity ratio values of copolymerization were calculated using 'H-NMR technique. Thermal analysis of the copolymers showed that the thermal stability are intermediate between poly (2-acrylamido-4-antipyrinyl) thiazole and poly methyl methacrylate homopolymers. The activation energies of the thermal degradation of the copolymers were calculated using Arrhenius relationship.

Physicochemical, optical and electrical investigation on poly [(phenylene-2-one)-co-(thiophene)] novel soluble conductive polymer as-synthesized through heterogeneous catalysis route

Although the use of conductive polymers has invaded the electronics industry, the insolubility parameter presents a major problem against their direct application on the surfaces of materials. Attachment of cyclic compounds to polymer chains is recommended to increase the solubility of conductive polymers. The aim of this study is to synthesize a new type of intrinsic conductive polymer, soluble in common solvents. The technique is based on the copolymerization of thiophene with a synthesized monomer phenylazepane-2-one. The reaction was catalyzed by a solid catalyst, prepared by the acid treatment of natural clay, generating active sites responsible for the adhesion of the thiophene and benzene rings. Proton and carbon nuclear magnetic resonances (1H NMR/13C NMR), ultraviolet spectroscopy (UV–Visible), infrared spectroscopy (IR) and differential scanning calorimetry (DSC) were used to identify the material obtained poly [(phenylazepane-2-one)-co-(thiophene)] abbreviated poly (PAT). Thermogravimetric analysis (TGA) showed the thermal stability of poly (PAT) before 200 °C. The solubility of poly (PAT) has been tested and confirmed in various common solvents. The indirect bandgap was calculated at 1.12 eV using Tauc formula. Ac electrical conductivity and dielectric permittivity have been studied versus frequency and temperature, showing the semiconductor character of poly (PAT). The results obtained showed that this novel polymer can play a pioneering role to replace conventional insoluble conducting polymers.

Significantly enhanced electrical and dielectric properties, and thermal stability of poly(3,4-ethylenedioxythiophene) coated on functionalized multiwalled carbon nanotubes

Poly(3,4-ethylenedioxythiophene)-functionalized multiwalled carbon nanotube [PEDOT―f-MWCNT] nanocomposites were prepared by in-situ chemical oxidation method using 3,4-ethylenedioxythiophene [EDOT] as monomer and f-MWCNT as nanofiller. Fourier-transform infrared-spectroscopy [FTIR] and X-ray diffraction [XRD] and field emission scanning electron microscopy [FESEM] revealed the successful formation and deposition of PEDOT on the surface of f-MWCNTs. The AC conductivity, σAC, dielectric properties, namely dielectric constant, ε', dielectric loss, ε”, tangent loss and quality factor, and thermal stability of PEDOT―f-MWCNT nanocomposites were investigated in the frequency range 10 Hz to 8 MHz, and temperature ranging from 30 to 950 °C, respectively. The results demonstrate that σAC of PEDOT―f-MWCNT nanocomposites increases with increasing the concentration of f-MWCNT in PEDOT matrix. In particular, ε' and σAC values of PEDOT-15 wt% f-MWCNT nanocomposite were about 3 and 45 times larger than those of pristine PEDOT. The residual weights of PEDOT-10 wt% f-MWCNT nanocomposite and pristine PEDOT at 600 °C were found to be nearly 44 wt% and 1.64 wt%, respectively, showing a significant improvement in the thermal stability of the nanocomposite. The observed electrical and dielectric properties, and thermal stability of PEDOT―f-MWCNT nanocomposites depict their possibilities for various electronic applications including thin-film transistors, electrodes, and photovoltaic cells.

Thermal stability of poly(N-vinylpyrrolidone) immobilized on the surface of silica in the presence of noble metals in an atmosphere of hydrogen and oxygen

Thermogravimetric analysis in combination with FTIR spectroscopy were used to assess the thermal stability and mechanism of degradation of poly(N-vinylpyrrolidone) (PVP) grafted on the surface of silica under oxidizing and reducing conditions before and after impregnation of noble metals. The structure of PVP immobilized on the silica surface is stable up to 175 °C regardless of the atmosphere of the process. The presence of a noble metal shifts the degradation of the polymer towards a lower temperature under reducing conditions while under oxidative conditions the degradation of the polymer occurs at a temperature close to bare PVP/SiO2. The lower thermal stability of Me/PVP/SiO2 (where Me = Pd, Ru, Rh, Pt) complexes compared to based PVP/SiO2 under reducing conditions is due to the high reactivity of the hydrogen molecule on the surface of impregnated metals.

Thermal Stability of Poly (vinyl chloride) Formulations Containing Iron Additives as a Replacement for Antimony Oxide

Poly (vinyl chloride) [PVC] is a widely used commodity polymer with particular application for wire and cable coating, and for pipe and profile extrusion. For processing, PVC must be heavily plasticized. In addition, a number of other additives are usually introduced to promote thermal stability, to enhance processability and to inhibit flammability. Antimony oxide is often used in PVC formulations. However, the growing concern about the negative health and environmental impacts of antimony oxide has stimulated efforts to find suitable replacements. Iron compounds have been examined as suitable replacements for antimony oxide. PVC formulations containing 45 phr of Pevalen plasticizer, 50 phr of magnesium hydroxide and 2 or 10 phr of an iron additive were processed using a two-roll mill at 180°C. The thermal degradation and flammability of these materials have been evaluated utilizing thermogravimetry (TGA) and limiting oxygen index (LOI) measurements. All of the iron additives are effective in increasing LOI for combustion of the blends and in promoting char formation. The impact of the presence of all the iron additives is comparable and independent of the oxidation level of iron. Based on considerations of cost and availability, simple iron oxide may be the additive of choice. Keywords: PVC additives; Antimony oxide replacements; Combustibility of formulated PVC; Impact of additives on the thermal stability of PVC;

Viscoelastic Behavior and Thermal Stability of Poly(Lactic Acid) Bio‐Composite Filled with Micro‐Graphite

AbstractPoly(lactic acid) or PLA bio‐composite is prepared by filling with micro‐graphite via solution blending. The micro‐graphite loading is varied from 0–15 wt%. The objectives of this research are to investigate the influence of micro‐graphite loading on PLA bio‐composite, on the viscoelasticity and thermal stability. The viscoelasticity behavior exhibits a considerable dependence on the melt properties of the PLA/micro‐graphite bio‐composites on the percentage micro‐graphite. The complex viscosity |η*|, storage modulus (G’), and loss modulus (G″) tend to improve with increasing micro‐graphite loading. Thermogravimetric analyses indicate that the micro‐graphite slightly stabilizes the PLA. The decomposition reaction is shifted to a higher temperature in the range 7–9 °C. This reaction leads to the loss of volatile byproducts, which occur at temperatures higher than 310 °C. It means far from the melt processing conditions. The differential scanning calorimetry thermogram shows that the glass transition temperature (Tg) and the melting temperature are close to that of neat PLA with changes only around 2–4 °C.

Erratum to: Synthesis of CaZnAl-CO3 ternary layered double hydroxides and its application on thermal stability of poly (vinyl chloride) resin

The second organization’s name was wrong and it should be replaced as follows: Kunming Training Corps, Fire and Rescue Bureau, Ministry of Emergency Management, Kunming 650208, China

Thermal stabilization of poly(acrylonitrile-co-itaconic acid) nanofibers as carbon nanofiber precursor

The thermal treatment of poly (acrylonitrile-co-itaconic acid), (P (AN-co-IA)) and polyacrylonitrile (PAN) under the oxygen atmosphere has a complex mechanism which strongly affects the properties of final product carbon nanofiber. Not only precursor composition but also oxidation treatment parameters play a key role in the achievement of the desired properties of the end product; carbon nanofiber. PAN and P (AN-co-IA) based nanofibers were fabricated via electrospinning technique and later treated at different temperatures to investigate the oxidation procedure in the presence of itaconic acid as a copolymer form. Description of the oxidation (thermal stabilization) route of nanofibers is challenging thus powerful characterization tools such as electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), and FTIR-ATR are used for characterization and evaluated dependently. All obtained results are pointed out that; IA addition has a positive effect on the oxidation process in nanoscale in terms of reduction of applied temperature and time compared to homopolymer PAN. Spectroscopic results were also correlated with the equivalent Circuit Parameters of Electrochemical Impedance Spectroscopic Measurements, where oxidation and carbonization stages can be followed easily due to the formation of heterocyclic and conjugated structures by thermal treatments.

Synthesis of CaZnAl-CO3 ternary layered double hydroxides and its application on thermal stability of poly (vinyl chloride) resin

Synthesis of CaZnAl-CO3 ternary layered double hydroxides and its application on thermal stability of poly (vinyl chloride) resin

Thermal stability of poly(l-lactide) α’ crystals and its blocking effect on perfection of α crystals

Thermal stability of poly(L-lactide) (PLLA) α’ crystals and its blocking effect on perfection of α crystals was reported in this manuscript. The results showed that, with annealing temperature (Ta) approaching to 150 °C, most α’ crystals transformed into α crystals, and the others with higher thermal stability still existed in those annealed samples. Interestingly, experiencing identical annealing, α crystals with residual α’ crystals displayed the bigger long period but the smaller lamella thickness than that of α crystals directly formed at 130 °C. Further, after the residual α’ crystals were totally melted, during annealing at a higher temperature, both lamella thickness and crystallinity of α crystals increased faster than that of α crystals with residual α’ crystals, even the latter was annealed at a lower temperature. This result is considered to promote understanding of the genesis of the PLLA α՛ crystals and the mechanism of α՛ to α transformation.

Thermally stable graft-type polymer electrolyte membranes consisting based on poly (ether ether ketone) and crosslinked graft-polymers for fuel cell applications

The effect of crosslinking on the thermal stability of poly (styrenesulfonic acid)-grafted poly (ether ether ketone) polymer electrolyte membranes (PEEK-PEMs) was investigated in water at 120 °C. The radiation-induced graft polymerization of an ethyl 4-styrenesulfonate (ETSS) monomer onto PEEK substrates, with divinylbenzene (DVB) (0.05, 0.1, 0.2, and 0.5 wt.%) as a crosslinker, followed by hydrolysis, generated crosslinker-containing PEEK-PEMs (PEEK-×0.05, -×0.1, -×0.2, and -×0.5), because the crosslinker (up to 0.5 wt.%) did not cause any destructive effect on the on grafting and hydrolysis rates. As a result, grafting degrees of 100–114% and ion exchange capacities (IECs) of 2.2–2.7 mmol/g, respectively, were achieved. Increasing the DVB amounts (from 0 to 0.5 wt.%), the conductivity, and water uptakes decreased; the PEEK-×0.5 showed a conductivity of 0.10 S/cm and water uptake of 43%. This confirms the successful incorporation of crosslinking structures on the graft-polymers. The hydrothermal test involved the immersion of PEMs in water at 120 °C for 500 h. The no-crosslinked PEEK-PEMs with the same IEC (2.7 mmol/g) experienced a decreases in the weight and IEC to 84 and 68% levels from the initial values, respectively, while those of crosslinked PEEK-×0.05 almost maintained their initial values (100 and 96%, respectively). These results indicated that very small amounts of crosslinkers can decreases the conductivity and the water absorption tendency while increasing the hydrothermal stability at higher temperatures.

Thermal stability of poly(diallyldimethylammonium chloride) with different molecular weight

The thermal stability of poly(diallyldimethylammonium chloride) (PDMDAAC) with serial molecular weights Mw ranged from 0.2850 × 106 to 1.144 × 106 was determined by TG-DSC. The decomposition activation energy of PDMDAAC, with different molecular weight was from 83.42 to 98.53 kJ/mol in Step I and from 163.63 to 223.68 kJ/mol in Step II, was obtained from TG with different heating rates, using the methods of Coats-Redfern and Ozawa. The evaluated decomposition activation energy Ea of PDMDAAC with Mw of 1.144 × 106 calculated by Ozawa method was 124.1 and 211.1 kJ/mol for each decomposition step, respectively. The results indicated that there were two decomposition steps for polymer PDMDAAC, while there was only one for its monomer DMDAAC. The calculation results by using the Coats-Redfern method indicated that the reaction order for two decomposition steps of PDMDAAC was both one. The Ea increased with the molecular weight of linear PDMDAAC. The thermal characteristic of crosslink products was more stable than the linear product.

A novel double agent of triazole-based zinc-containing complex which constituted Zn/Zn stabilizer system with zinc stearate as thermal stabilizer for poly(vinyl chloride)

An effectively Zn/Zn stabilizer system instead of traditional Ca/Zn stabilizer system was put forward, which contained a new triazole-based zinc-containing complex (abbreviated as [Zn(ttr)(St)]) and Zinc stearate (ZnSt2). Without Ca soap in the system, [Zn(ttr)(St)] itself could effectively absorb HCl and provided PVC with higher transparency and better thermal stability without “zinc burning” than commercial CaSt2/ZnSt2 stabilizer system, verified by Congo red tests and discoloration tests and dynamic thermal stability analysis. In addition, [Zn(ttr)(St)] could further delay “zinc burning” of other zinc soaps, constituting Zn/Zn stabilizer system. This is attributed to the strong ability of restricting ZnCl2 of 3-amino-1,2,4-triazole released from [Zn(ttr)(St)] after absorbing HCl. After adding ESBO, PVC stabilized by [Zn(ttr)(St)]/ZnSt2/ESBO showed excellent transparency and thermal stability. We believe that [Zn(ttr)(St)] can act as a novel double agent with the stabilization effects of zinc soap and calcium soap at the same time and this Zn/Zn stabilizer system may inaugurate a new stabilizer system for PVC with synergistic effect.

Following the morphological and thermal properties of PLA/PEO blends containing carbon nanotubes (CNTs) during hydrolytic degradation

In this article, the morphology, melting behavior, crystallinity and thermal stability of poly (lactic acid) (PLA)/poly (ethylene oxide) (PEO) blends and PLA/PEO/carbon nanotubes (CNTs) nanocomposites are studied before and after the hydrolytic degradation in neutral phosphate-buffered saline (PBS) solution. The morphologies of all the samples show PEO droplets in a continuous PLA phase, but the addition of CNTs to the blends diminishes the size of the PEO particles and homogenizes their dispersion before and after degradation. Additionally, the degradation did not change the morphologies of the samples. The samples showed two different melting peaks, indicating that the PLA/PEO blend is not miscible. The low crystallinity of PLA in the degraded samples was due to the short chains and high cold crystallization. The thermal decomposition of the samples occurred in two stages, demonstrating the poorer thermal stability of PLA compared to PEO. The positive and negative roles of CNTs in the thermal stability depend on the concentrations of PLA and CNTs, which determine the protective role or heat transfer of CNTs in the samples.