Thermal Stability Of Poly Research Articles

Synthesis and characterization of polyesters from renewable cardol

The preparation and thermal characteristics of new polyesters from cardol, a renewable monomer obtained as a by-product of the cashew industry, are reported. Cardol - a diol component of the natural product cashew nut shell liquid (CNSL) was isolated and reacted with adipoyl chloride and terephthaloyl chloride in a 1:1 molar ratio in hexane and toluene as solvents at 170 °C under nitrogen atmosphere. The cardol based polyesters [poly(cardyl adipate) and poly(cardyl terephthalate)] were produced in good yields of up to 63 and 54%, respectively. The polymers were analysed by FT-IR for functional groups elucidation and by combined thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) for thermal stability. The cardol-based polyesters were thermally stable up to about 400 °C. The thermal stability of poly(cardyl terephthalate) was higher than that of poly(cardyl adipate) under similar conditions. All prepared polyesters were insoluble in common laboratory solvents at room temperature. KEY WORDS : Cashew nut shell liquid, Cardol, Polyesters, Renewable polymers Bull. Chem. Soc. Ethiop. 2016 , 30(2), 273-282. DOI: http://dx.doi.org/10.4314/bcse.v30i2.11

Thermal degradation of poly(3-hydroxybutyrate)/poly(ethylene oxide) blends: Thermogravimetric and kinetic analysis

Thermal stability of poly(3-hydroxybutyrate)/poly(ethylene oxide) (PHB/PEO) blends has been investigated by non-isothermal thermogravimetry in an inert atmosphere. PHB/PEO blends were prepared by hot-melt extrusion. Neat polymers decompose in one stage and PHB/PEO blends in two degradation stages, respectively. It was found that the degradation of investigated blends starts at lower temperatures and occurs more slowly by addition of PEO, that could be an indication of PEO’s destabilising effect on PHB. Kinetic analysis of the non-isothermal degradation of PHB/PEO blends was performed using isoconversional Friedman (FR) method in combination with the multivariate non-linear regression method. The kinetic analysis indicated three-stage degradation mechanism for all investigated samples, except for PEO sample which showed two-stage degradation mechanism. PEO showed higher value of activation energy confirming its superior thermal stability to PHB.

Poly(ethylene glycol)–polyhedral oligomeric silsesquioxane as a novel plasticizer and thermal stabilizer for poly(vinyl chloride) nanocomposites

AbstractThe plasticizing and thermostabilizing effect of poly(ethylene glycol)–polyhedral oligomeric silsesquioxane (PEG‐POSS) on poly(vinyl chloride) (PVC) is discussed thoroughly in this work. As PEG‐POSS content increases, PVC becomes more flexible and the decomposition temperature of PVC increases slightly. Meanwhile, the temperature of maximum HCl emission is elevated from 265.3 °C in neat PVC to 285.7 °C in PVC nanocomposites, with the peak intensity of HCl emission decreased by 30.8%, and a new lower intensity of HCl emission peak appearing at much higher temperature (around 370 °C), which is in accordance with the maximum degradation temperature of PEG‐POSS. Thereby, a possible dehydrochlorination mechanism is suggested according to the fact that the electron donor effect of ether groups would stabilize the CCl bonds by means of more electron cloud stacked in those bonds, which agrees with Fourier transform infrared and X‐ray photoelectron spectroscopy experiments in terms of hydrogen bonds. © 2016 Society of Chemical Industry

Effect of Graphite Oxide Dispersion Evaluated with Multifractal on Mechanical Properties and Thermal Stability of Poly(3hydroxybutyrate‐co‐4hydroxybutyrate)/Graphite Oxide Biocomposites

ABSTRACTPoly(3hydroxybutyrate‐co‐4hydroxybutyrate) [P(3HB‐co‐4HB)]/graphite oxide (GO) composites were fabricated using a solution mixing method. The GO structures in the composites were analyzed by using transmission electron microscopy, Raman spectroscopy, and X‐ray diffraction. The fracture morphology of the samples was evaluated by the multifractal, and the effect of GO dispersion on the mechanical properties and the thermal stability were discussed for the P(3HB‐co‐4HB) and the composites. It was found that the interlayer spacing of the GO increased due to the intercalation of the polymer into the GO platelets. As the GO content increased, the relative multifractal spectrum increased, but the mechanical properties declined for the composites, indicating that the filler agglomeration effect overcame the reinforcement benefits for the high loadings of the GO. Moreover, both good dispersion and high content of the GO platelets increased the thermal stability of the composites. Therefore, the relative multifractal spectrum width of the fracture morphology was related to the mechanical properties and the thermal stability of the composites.

Remarkably improved toughness and thermal stability of poly (vinyl chloride) (PVC)/poly (α-methylstyrene-acrylonitrile) (α-MSAN) blend with the assistance of two impact modifiers

The key drawback of impact modifier-toughened polymer is that the improved toughness is accompanied by loss in stiffness. Surprisingly, poly (vinyl chloride) (PVC)/poly (α-methylstyrene-acrylonitrile) (α-MSAN) blend was toughened without loss in stiffness by simply combining two impact modifiers-chlorinated polyethylene (CPE) and acrylic resin (ACR). The prepared blend's impact strength was 3.0 times higher than PVC/α-MSAN/CPE blend and 18.6 times higher than pure PVC/α-MSAN blend. An impressive thermal stabilizing effect was also achieved when CPE and ACR were combined. The improved toughness could be attributed to the overlap of the stress field between different impact modifiers, which help to form the continuum percolation of stress volume under impact loading.

Composite based on poly(acrylic acid‐co‐itaconic acid) hydrogel with antibacterial performance

Novel composites have been prepared via the incorporation of zinc oxide nanoparticles (nZnO) into poly(acrylic acid‐co‐itaconic acid) (poly(AA‐co‐IA)) hydrogel. The prepared composites were characterized by means of Fourier transform infrared spectroscopy (FT‐IR), swelling studies, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The amount of nZnO incorporated into hydrogel was determined by using atomic absorbance spectrometry. In addition, the antibacterial performance of composites was evaluated against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). SEM characterization of the composite hydrogels revealed a homogeneous distribution of the nZnO throughout the hydrogel with formation of some agglomerates. A progressive rise in thermal stability of poly(AA‐co‐IA) is found with increasing nZnO concentration. nZnO/poly(AA‐co‐IA) composites showed antibacterial activity against both bacteria. The approach used in this work is an efficient method to develop new hydrogel‐based wound dressing composites for use in biomedical applications. POLYM. COMPOS., 39:171–180, 2018. © 2016 Society of Plastics Engineers

Biodegradable poly(lactic acid)/poly(butylene succinate)/wood flour composites: Physical and morphological properties

This work sought to improve the toughness and thermal stability of poly(lactic acid) (PLA) by incorporating poly(butylene succinate) (PBS) and wood flour (WF). The PLA/PBS blends showed a PBS‐dose‐dependent increase in the impact strength, elongation at break, degree of crystallinity, and thermal stability compared to the PLA, but the tensile strength, Young's modulus, and flexural strength were all decreased with increasing PBS content. Based on the optimum impact strength and elongation at break, the 70/30 (w/w) PLA/PBS blend was selected for preparing composites with five loadings of WF (5–30 phr). The impact strength, tensile strength, flexural strength, and thermal stability of the PLA/PBS/WF composites decreased with increasing WF content, and the degree of crystallinity was slightly increased compared to the 70/30 (w/w) PLA/PBS blend. Based on differential scanning calorimetry, the inclusion of PBS and WF into PLA did not significantly change the glass transition and melting temperatures of PLA in the PLA/PBS blends and PLA/PBS/WF composites. From the observed cold crystallization temperature of PLA in the samples, it was evident that the degree of crystallinity of PLA in all the blends and composites was higher than that of PLA. The PLA/PBS blend and PLA/PBS/WF composite degraded faster than PLA during three months in natural soil, which was due to the fast degradation rate of PBS. POLYM. COMPOS., 38:2841–2851, 2017. © 2016 Society of Plastics Engineers

Mixed calcium and zinc salts of N-(3-amino-benzoic acid)terpene-maleamic acid: preparation and its application as novel thermal stabilizer for poly(vinyl chloride)

N-(3-Amino-benzoic acid)terpene-maleamic acid was successfully prepared, and converted to the corresponding good efficient Ca/Zn-based thermal stabilizers for poly(vinyl chloride).

A Study on Physical Performance for Poly(L-lactic acid) in Addition to Layered Strontium Phenylphosphonate

The organic-inorganic hybrid layered strontium phenylphosphonate (SrP) was synthesized by using strontium chloride and phenylphosphinic acid. And the influence of layered SrP on the crystallization behavior and thermal stability of poly(L-lactic acid) (PLLA) was investigated through DSC, XRD, and TGA. Both DSC and XRD results demonstrated that layered SrP had the powerful accelerated ability for PLLA crystallization, and in the range of studied concentration, 0.7 wt%–1 wt% is the optimum concentration range to achieve rapid crystallization of PLLA. Meantime, as a result, the increase of cooling rate in nonisothermal crystallization procedure seriously affected the crystallization accelerated efficiency of SrP. Thermal stability measurement showed that layered SrP could cause the onset decomposition temperature of PLLA to decrease, but the thermal decomposition behavior of PLLA hardly depended on the SrP concentration.

Effect of a Multifunctional Chain Extender on the Mechanical Properties and Thermal Stability of Poly (lactic acid) Synthesized via Direct Polycondensation

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Segmental dynamics, morphology and thermomechanical properties of electrospun poly(ε-caprolactone) nanofibers in the presence of an interacting filler

The effect of addition of an interacting nanofiller (Cloisite 10A) on the segmental dynamics, morphology and thermal stability of poly(ε-caprolactone) (PCL) is subjected to detailed investigation.

Synthesis, characterization, and thermal stability of poly (lactic acid)/zinc oxide pillared organic saponite nanocomposites via ring-opening polymerization ofd,l-lactide

Synthesis, characterization, and thermal stability of poly (lactic acid)/zinc oxide pillared organic saponite nanocomposites via ring-opening polymerization of<scp>d</scp>,<scp>l</scp>-lactide

Effect of base‐deposited graphene oxide on the thermal stabilization of poly(vinyl chloride)

AbstractGraphene oxide was deposited in a base solution to form base‐deposited graphene oxide (bd‐GO) particles. The structure and properties of the bd‐GO particles were evaluated using transmission electron microscopy, powder X‐ray diffraction and X‐ray photoelectron, Fourier transform infrared, UV‐visible and fluorescence spectroscopies. The effect of the bd‐GO particles on the thermal stabilization of poly(vinyl chloride) (PVC) was investigated using the Congo red test and thermogravimetric analysis. The results showed that the thermal stability of PVC was greatly improved by the bd‐GO particles. Furthermore, this stabilization mechanism was investigated using UV‐visible spectroscopy and nitrogen adsorption–desorption isotherm analysis. It was found that the improvement of thermal stability was mainly related to the deactivation of thermally labile structural defects in the PVC chains by the carboxylate and alkoxide moieties of the basic groups in the bd‐GO particles, and the highly efficient adsorption of the bd‐GO particles with hydrogen chloride produced during PVC degradation. © 2015 Society of Chemical Industry

Poly(thieno[3,4–b]–1,4–oxathiane): Effect of solvent on the chemical synthesis and capacitance comparison in different electrolytes

Thieno[3,4-b]-1,4-oxathiane (EOTT), one asymmetrical analog of 3,4-ethylenedioxythiophene (EDOT), was synthesized and its chemical oxidative polymerization was carried out in different solvents (dichloromethane, water, and acetonitrile (CH2Cl2, H2O, and ACN)). The effect of the solvent on the structure, crystalline characteristic, morphology, and thermal stability of poly(thieno[3,4-b]-1,4-oxathiane) (PEOTT) were investigated by fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray diffraction, scanning electron microscopy, and thermogravimetry, respectively. PEOTT prepared from H2O exhibited higher electrical conductivity (∼100S/cm) and more robust thermal stability. The electrochemical capacitance performance of PEOTT electrode in ACN–LiClO4 was initially found dissatisfactory. Furthermore, the electrochemical properties of this electrode in another three aqueous electrolytes (H2SO4, HClO4, and LiClO4) were also investigated comparatively by cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS). It revealed the enhanced specific capacitance (208F/g at 1A/g) and improved capacitance retention (80.4% after 1000 cycles at 10A/g) of PEOTT electrode in H2O–HClO4 compared to those of the electrode in ACN–LiClO4. These results implied that PEOTT employing aqueous HClO4 electrolyte should be a promising electrode material for supercapacitor applications.

Morphologies, mechanical properties and thermal stability of poly(lactic acid) toughened by precipitated barium sulfate

Poly(lactic acid) (PLA)-based composites were prepared by blending PLA with precipitated barium sulfate (BaSO4) modified with stearic acid. The morphologies, mechanical properties and thermal stability of samples with increased mass fraction of BaSO4 were investigated. Results showed that PLA was toughened and reinforced simultaneously by incorporation of precipitated BaSO4 particles. The highest impact toughness and elongation at break were both achieved at 15% BaSO4, while the elastic modulus increased monotonically with increasing BaSO4 loading. Little effect of BaSO4 on the thermal behavior of PLA was observed in the present case. However, the thermal stability of PLA/BaSO4 composites at high temperature was enhanced.

Lanthanum histidine with pentaerythritol and zinc stearate as thermal stabilizers for poly(vinyl chloride)

ABSTRACTLanthanum histidine [La(His)2·(NO3)·2H2O or La(His)2] was synthesized via the reaction of histidine and lanthanum nitrate, and it was investigated as a stabilizer for poly(vinyl chloride) (PVC). The results show that La(His)2 exhibited a stabilizing effect on PVC as a long‐term stabilizer because it prolonged the stability time of PVC to 76 min, which was about 24 times longer than the stability time of the pure PVC. The stabilizing effect of La(His)2 as a costabilizer with pentaerythritol (Pe) and zinc stearate (ZnSt2) was also studied. The results show that the use of La(His)2 with Pe or Pe/ZnSt2 improved the stability time of PVC. La(His)2/Pe/ZnSt2 provided PVC with a good initial color and long‐term stability, and when it was prepared at mass ratios of 0.8:2.4:0.8 and 1.6:1.6:0.8, the stability times of PVC were improved to 86 and 88 min, respectively. As a nontoxic stabilizer, La(His)2/Pe/ZnSt2 has the potential to replace the toxic stabilizers widely used in PVC manufacturing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42878.

The surface modification of CuO nanoparticles with a flame retardant coupling agent and their influence on the thermal stability of poly(amide-imide)/CuO nanocomposites

The present work reports the fabrication and characterization of the thermally stable poly(amide–imide)/CuO nanocomposites. For this purpose, a biodegradable and optically active poly(amide–imide) was synthesized through polycondensation reaction under green media. Subsequently, the surface of CuO nanoparticles was modified with 2,3,4,5-tetrabromo-6-[(4-hydroxyphenyl) carbamoyl] benzoic acid as a new coupling agent to increase their dispersity. The modified nanoparticles were characterized by different methods. The results of Fourier-transform infrared spectra confirmed that the modifier was successfully grafted on the surface of nanoparticles. Finally, the different amounts of modified CuO nanoparticles (2, 4, and 6 wt%) were dispersed in the poly(amide–imide) matrix via sonochemical reaction. The obtained nanocomposites were studied by Fourier-transform infrared, X-ray diffraction, thermogravimetric analysis, field emission scanning electron microscopy, and transmission electron microscopy. The data obtained by Fourier-transform infrared demonstrated the possible incorporation of CuO nanoparticles in the poly(amide–imide) matrix. Field emission scanning electron microscopy and transmission electron microscopy analyses showed that CuO nanoparticles were homogeneously distributed in the polymer matrix. The combination of nanoparticles and poly(amide–imide) can lead to the improvement in thermal stability property of the resulting nanocomposites.

Investigation of the effects of nonisothermal suspension polymerization of vinyl chloride on the fusion and degradation behavior of poly(vinyl chloride)

Thermal stability of poly(vinyl chloride) (PVC) samples polymerized under a temperature trajectory was studied from the point of view of morphological and microstructural characteristics. The results are compared with those of the PVC samples obtained by polymerization at constant temperature having the same K value. The Brabender® plastograph data indicated that the final PVC synthesized with the temperature trajectory showed lower fusion time and higher thermal stability time. The nonisothermal condition also increased the degree of fusion of the final PVC resin, reflecting lower temperature/time required to process it. It was found that the thermal stability of nonisothermally produced PVC as characterized by dehydrochlorination rate decreased (improved) with the increasing monomer conversion until a minimum value was reached that corresponded to the conversion at the pressure drop. However, the dehydrochlorination rate remains almost constant with conversion for an isothermal grade PVC resin. Although the evolution of the number of internal double bonds as well as extent of discoloration of PVC with conversion shows a decreasing trend, the labile chlorine concentration exhibits a maximum at early conversion. The reason for the former can be explained by the temperature dependence of reactions forming defect structures, which are kinetically controlled and thus favored at higher temperatures. The latter, however, can be explained because of the increasing importance of transfer reactions to polymer with increasing polymer concentration. Finally, the results from differential thermogravimetry verify an improvement in thermal stability of the final PVC prepared by using a temperature trajectory during vinyl chloride monomer suspension polymerization. J. VINYL ADDIT. TECHNOL., 23:259–266, 2017. © 2015 Society of Plastics Engineers

Effects of montmorillonite and compatibilizer on the mechanical and thermal properties of dispersing intercalated PMMA nanocomposites

We added montmorillonite (MMT) to improve the mechanical properties and thermal stability of poly (methyl methacrylate) (PMMA). We used a twin-screw extruder to produce standard specimens for examinations. We examined the layer distance of MMT and mechanical properties of the nanocomposites containing various amounts of MMT. The chemical structure and morphology of specimens were characterized with wide-angle powder X-ray diffraction, scanning, and transmission electron microscopy techniques. It was observed that by increasing the amount of MMT, layer distance increased from 2.16 to 3.87nm for the composite containing 5 wt% MMT. In the tensile and impact properties examinations, the composite containing 1% MMT revealed the best result with increase of 1.81%. The shore hardness and wear resistance properties were also significantly improved. The beginning of thermal decomposition of nanocomposites slightly shifted to a higher temperature, compared with the thermogram of pure PMMA.

Thermal stability of poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate)/modified montmorillonite bio‐nanocomposites

Poly(3‐hydroxybutyrate‐co‐4‐hydroxybutyrate) (P34HB)/modified montmorillonite (EMMT) bio‐nanocomposites were prepared via melt intercalation method. The thermal stability of the bio‐nanocomposites was investigated. The results showed that the decomposition temperature (T5%) of P34HB/EMMT bio‐nanocomposite reached 271.4°C, 39.9°C higher than that of pure P34HB. The remarkable thermal stability enhancement was presumably originated from the uniform dispersion of EMMT in the matrix and intercalated structures of P34HB/EMMT bio‐nanocomposites, which was related to the increased compatibility of EMMT and P34HB caused by the ester group in EMMT. TGA‐FTIR analysis on the thermal degradation procedures of the bio‐nanocomposites manifested that the introduction of EMMT did not alter the degradation mechanism of P34HB. However, the intercalated structures hindered the mobility of P34HB macromolecular and slowed down the decomposing process of P34HB. POLYM. COMPOS., 38:673–681, 2017. © 2015 Society of Plastics Engineers