Stability Of PVC Research Articles

Modelling the Thermal Degradation and Stabilisation of PVC in a Torque Rheometer

Abstract A novel method for simulating the torque and temperature curves from a torque rheometer thermal stability test on poly(vinyl chloride) (PVC) was developed. A mathematical model was proposed which combines the chemical kinetics involved in the thermal degradation and stabilisation process of PVC with heat transfer and viscosity relationships within the torque rheometer. The model coefficients were fitted to data obtained from previous experiments with a program written in the Python programming language using the Levenberg-Marquardt Algorithm (LMA) with multiple starts. The mathematical model fits the torque rheometer data successfully depending on the characteristics of the torque curve. The model fit is successful when the torque curve follows the expected behaviour. An unsuccessful model fit occurs when the torque curve deviates from the expected shape in a very specific way. In the degradation phase the torque curve increases to a local maximum, decreases to a local minimum and then increases again. The exact reason for the dip in torque is unknown.

Solid‐state organo‐modification of montmorillonite for manufacturing of plasticized poly(vinyl chloride) nanocomposites

The preparation of poly(vinyl chloride) (PVC) nanocomposites via direct melt processing is still posing problems mainly because of the lack of availability of suitable commercial organoclays and because of the low thermal stability of PVC. A new type of organic compounds for modifying montmorillonite (MMT), which is suitable for use in plasticized PVC, has been found earlier. The current study shows that it is possible to achieve partially exfoliated PVC nanocomposites with greatly improved mechanical properties using a method of liquid‐solid–state intercalation of MMT when using tributyl citrate and diisononyl phthalate (DINP) plasticizers as organic modifiers. It is also shown that liquid mixed metal stabilizers have the ability to intercalate the clay at least when DINP is used. The observation raises questions regarding how this phenomenon can affect the thermal stability of PVC composites. J. VINYL ADDIT. TECHNOL., 24:E146–E153, 2018. © 2017 Society of Plastics Engineers

UV-Absorbing Cellulose Nanocrystals as Functional Reinforcing Fillers in Poly(vinyl chloride) Films

Ultraviolet (UV)-responsive poly(cinnamoyloxy ethyl methacrylate) (PCEM) was grafted on cellulose nanocrystals (CNCs) via the surface-initiated atom transfer radical polymerization technique. The resultant PCEM-grafted CNCs (PCEM-g-CNCs) exhibit high UV absorption properties and undergo cross-linking when subjected to UV radiation. When the PCEM-g-CNC nanohybrids were incorporated into poly(vinyl chloride) (PVC) matrix, transparent nanocomposite films with UV-blocking characteristics were obtained. Comparison of the optical and mechanical properties of the films before and after UV irradiation confirmed that the PCEM-g-CNCs are excellent thermal and UV stabilizers for PVC. In addition, the tensile properties of the PVC film were increased significantly and further enhanced after UV irradiation.

Study of Coffee Grounds Oil Action in PVC Matrix Exposed to Gamma Radiation: Comparison of Systems in Film and Specimen Forms

The poly (vinyl chloride), PVC, undergoes changes in its physicochemical properties when it is exposed to gamma radiation. Thus, the radiolytic stabilization of PVC is one way for obtain a material with radiation resistance. In this work, we studied the coffee grounds oil as PVC radiolytic protection in two systems forms: PVC film and PVC specimen. The systems were irradiated at sterilization dose of medical devices and viscosity measurements were performed. According to viscosity assays of PVC films, there was a 67% protection in polymer matrix promoted by the oil. On the other hand, the mean viscosity molar mass (Mv) of PVC specimens increased about 13%, indicating predominance of crosslinking effect, however samples containing the oil showed no Mv significant changes. Therefore, the oil can be considered a PVC radio stabilizing substance and open a way for use of sustainable additive in PVC industry.

Biologically active maleimido aromatic 1,3,4-oxadiazole derivatives evaluated thermogravimetrically as stabilizers for rigid PVC

Four novel N-aryl maleimide-bearing aromatic 1,3,4-oxadiazole systems were synthesized via a thermally induced cyclodehydration reaction of their corresponding precursors maleimido aromatic hydrazide derivatives. Their chemical structures were confirmed by elemental analyses, FTIR, 1H-NMR and mass spectroscopy. They showed a good antimicrobial activity against Bacillus subtilis, Streptococcus pneumoniae, Escherichia coli, Aspergillus fumigatus, Geotrichum candidum and Syncephalastrum racemosum using agar well diffusion method. The investigated derivatives are thermally stable and start decomposition in the temperature range above 250–300 °C. They were investigated for thermal stabilization of rigid PVC using thermogravimetric analysis technique, in nitrogen. They showed a greater stabilizing efficiency as illustrated by their higher initial decomposition temperature and higher residual mass percent at particular temperatures relative to dibasic lead carbonate, cadmium–barium–zinc stearate complex and di-n-octyltin bis (isooctylmercaptoacetate) (n-octyltin mercaptide, n-OTM) reference thermal stabilizers. Their stabilizing efficiency is also demonstrated by lower rates of both discoloration and degree of chain scission of the polymer during degradation. The electron-donating substituent groups in the aromatic ring of 1,3,4-oxadiazole part of these derivatives increased their stabilizing efficiency.

Phosphate ester groups‐containing ricinoleic acid‐based Ca/Zn: Preparation and application as novel thermal stabilizer for PVC

ABSTRACTPhosphate ester groups containing ricinoleic acid‐based Ca/Zn (LPPRA‐Ca and LPPRA‐Zn) stabilizer was successfully synthesized from ricinoleic acid (RA) and used as thermal stabilizers for poly(vinyl chloride) (PVC). These thermal stabilizers were characterized by Fourier transform infrared spectrometry, 1H nuclear magnetic resonance, and inductively‐coupled plasma atomic emission spectroscopy. The effects of LPPRA‐Ca/LPPRA‐Zn, CaSt2/ZnSt2, and other stabilizers on the thermal stability of PVC were studied through Congo Red test, discoloration tests, thermogravimetric analysis (TGA), TGA–infrared, and TGA–mass spectrometry. The thermal stability tests show that LPPRA‐Ca/LPPRA‐Zn displays the best initial color stability and long‐term thermal stability for PVC. The superior performance is attributed to the synergistic effect of LPPRA‐Ca and LPPRA‐Zn. Moreover, a lower Zinc content of LPPRA‐Zn in PVC helps to decrease the “zipper dehydrochlorination” of the product, which contributes to a better initial thermal stability. Except for the better stabilization performance, LPPRA‐Ca/LPPRA‐Zn also displays better plasticization performance for PVC compared with other stabilizers. A possible stabilizing mechanism of PVC/LPPRA‐Ca/LPPRA‐Zn system was presented. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45940.

Preparation and characterization of graphene enriched poly(vinyl chloride) composites and fibers

In this paper, poly(vinyl chloride)/graphene (PVC/G) composite fibers are extruded through a set of wet spinning unit for the purpose of properties improvement, including mechanical strength, thermal stability, and electrical conductivity. PVC/G composite membranes are also prepared using a spin-coating method for the analysis on the distribution of graphene in PVC composite. The PVC/G composite fibers are systematically characterized by means of Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and X-ray Diffraction. The mechanical, thermal, and electrical properties of the prepared PVC/G composite fibers are also analyzed. The experimental results show that the graphene sheets at a low concentration of 1–5 wt% can be distributed homogeneously in the PVC matrix; the mechanical properties, thermal stability, and electrical conductivity of PVC can be enhanced significantly by the blending of graphene sheets.

Thermogravimetric evaluation of novel antimicrobial phthalimido aromatic 1,3,4-oxadiazole derivatives as stabilizers for rigid PVC

A series of novel N-aryl phthalimides containing the aromatic 1,3,4-oxadiazole system has been synthesized starting from their corresponding precursors phthalimido aromatic hydrazide derivatives via a thermally induced cyclodehydration reaction. The synthesized derivatives' structures were elucidated on the basis of elemental analyses, FTIR, 1H-NMR, and mass spectroscopy. They were screened for antibacterial activity against Bacillis subtilis and Streptococcus pneumoniae as Gram-positive bacteria and against Escherichia coli as Gram-negative bacteria and for antifungal activity against Aspergillus fumigatus, Geotricum candidum and Syncephalastrum racemosum fungi by agar well diffusion method. They showed good antimicrobial activity as judged by their high inhibition zone diameter and low minimum inhibition concentration. They are more potent against Gram-positive bacteria than against Gram-negative bacteria. Some of the prepared derivatives displayed comparable or even better antibacterial and antifungal activities than the reference bactericides or fungicides. These derivatives were evaluated as thermal stabilizers for rigid PVC using thermogravimetric analysis under a nitrogen atmosphere. They exhibited improved heat stabilizing effects relative to dibasic lead carbonate (DBLC), cadmium-barium-zinc (Cd-Ba-Zn) stearate complex and di-n-octyltin bis (isooctylmercaptoacetate) (n-octyltin mercaptide, n-OTM) reference thermal stabilizers as shown by their higher initial decomposition temperature and higher residual weight percent at particular temperatures. Their stabilizing efficiency is also illustrated by lower rates both of discoloration as well as degree of chain scission of the polymer during degradation. The stabilizing efficiency increased with the introduction of electron donating substituent groups in the aromatic ring of 1,3,4-oxadiazole part of these derivatives.

Thermal and mechanical properties of bio-based plasticizers mixtures on poly (vinyl chloride)

The use of mixtures of nontoxic and biodegradable plasticizers coming from natural resources is a good way to replace conventional phthalates plasticizers. In this study, two secondary plasticizers of epoxidized sunflower oil (ESO) and epoxidized sunflower oil methyl ester (ESOME) were synthesized and have been used with two commercially available biobased plasticizers; isosorbide diesters (ISB) and acetyl tributyl citrate (ATBC) in order to produce flexible PVC. Different mixtures of these plasticizers have been introduced in PVC formulations. Thermal, mechanical and morphological properties have been studied by using discoloration, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), tensile - strain and scanning electron microscopy (SEM). Studies have shown that PVC plasticization and stabilization were improved by addition of plasticizers blends containing ISB, ATBC, ESO and ESOME. An increase in the content of ESO or ESOME improved thermal and mechanical properties, whereas ESOME/ATBC formulations exhibited the best properties.

Hyperbranched polyglycerol nanoparticles based multifunctional, nonmigrating hindered phenolic macromolecular antioxidants: Synthesis, characterization and its stabilization effect on poly(vinyl chloride)

A facile synthesis of multifunctional hindered phenolic macromolecular antioxidants based on hyperbranched polyglycerol (HbPG) nanoparticles as cores with different molecular weights is reported. The structure of the resulting polymers was verified by 1H NMR and UV–Vis spectroscopies indicating 64–77% antioxidant functionalizations of the hydroxyl groups of the HbPGs. GPC analyses show that polymeric antioxidants with PDI of 1.33–1.66 are formed. DSC and TGA measurements revealed Tg of ∼40 °C and high thermal stability up to ∼300 °C of the multifunctional HbPG-antioxidant conjugates, respectively, confirming that these materials are liquids and stable at usual polymer processing temperatures. The efficiency of the synthesized antioxidants in thermooxidative stabilization of PVC was investigated, keeping in mind that although the importance and wide application of PVC, especially in biomedical fields are incontestable, the utilization of macromolecular antioxidants for the stabilization of PVC has not been examined so far. It was found that the macromolecular antioxidants show similar stabilizing efficiency as the tetrafunctional industrial Irganox1010. Very low extent of leaching of the HbPG-antioxidant from PVC, investigated by extraction tests in both water and hexane, was observed in both extracting agents in contrast to the case of the low molecular weight hindered phenolic antioxidant. Thus, the obtained results confirm the advantages, i.e. high efficiency and highly suppressed leaching, of HbPG-based macromolecular antioxidants in a variety of application fields.

Abdussamad Abubakar1, Abdullahi Muhammad2, Dayyabu Shehu3, Murtala Ya’u3, Abba Babandi3, Abubakar Sadiq Tanko4, Ferdaus Mohamat-yusuff5, Hadiza Ibrahim6 and Salihu Ibrahim2*

Tributyltin (TBT) is one of the most toxic substances ever deliberately introduced into the marine environment. It is an organotin compound mostly used as wood preservative, pesticide, bactericide, PVC stabilizer, fungicide, antifouling biocide in boat and ships paints to prevents attachments of the marine organism on the hull surface.We studied the TBT-Resistant Bacterium by Klebsiella sp. FIRD 2 containing copper II ion and modelled it using several kinetic models such as Monod, Haldane, Luong, Aiba, Teissier, Yano, and Webb and estimated the accuracy of the fitted model using statistical analysis such as coefficient of determination (R2), adjusted coefficient of determination (adj R2), and root mean square (RMSE). Aiba model was the best model to the experimental growth kinetics data determined and gave a very good fit. The estimated value for the Aiba constants in this work such as maximal growth rate, half inhibition constant, and half saturation constant rate designated asumax, ki andks were 0.1265 hr-1, 8.061 mg/Land 0.8300 mg/L respectively. The true umax where the gradient for the slope is zero for the Aiba model was approximately 0.061093 hr-1 at 1 mg/Lcopper.

Effect of Copper Sulfide Nanoparticles in Poly(vinyl chloride) Exposed to Gamma Irradiation

Hybrid organic–inorganic materials combine both typical inorganic and organic material properties, allowing them to be applied in a wide range of areas, including radiation-resistant polymers. In this study, Copper sulfide (CuS) is presented as an unprecedented inorganic radiolytic stabilizer for Poly(vinyl chloride). CuS nanoparticles were synthesized from copper (II) chloride (CuCl2) and thioacetamide (CH3CSNH2) by sonochemical route. TEM image showed the size of CuS nanoparticle ranging around 50 nm in diameter. Commercial PVC containing CuS nanoparticles in concentrations of 0.10; 0.30; 0.50 and 0.70 wt% were irradiated with gamma radiation (60Co) at room temperature in air. Samples containing 0.5 wt% of CuS nanoparticles showed no detectable decrease in viscosity-average molar mass (Mv), while appreciable degradation was seen in the remaining samples. These results suggest that the addition of CuS nanoparticles imparted molecular protection to the polymer matrix. The observed FTIR band shifts indicate the intermolecular interactions between the CuS and the PVC matrix. These interactions favored the action of nanoparticles as a plasticizer in PVC matrix. In addition, the CuS act as thermal stabilizer because an increase in PVC thermal degradation onset temperature was evidenced. Our findings pave the way to the use of CuS as a nanostructured multifunctional stabilizer for PVC.

Evaluation of the stability of rigid poly(vinyl chloride)/biologically active phthalimido phenyl urea composites using thermogravimetric analysis

Four novel phthalimido phenyl urea derivatives, prepared by a low temperature solution condensation reaction between N-[4-(chlorocarbonyl) phenyl] phthalimide and either of phenyl urea, p-methyl phenyl urea, o-chloro phenyl urea or p-carboxy phenyl urea, have been investigated as antimicrobial thermal stabilizers for rigid PVC. They were characterized by FTIR, 1H-NMR, mass spectra, elemental analysis and antimicrobial activity. Their antibacterial activities against Bacillis subtilis and Streptococcus pneumoniae as Gram-positive bacteria and against Salmonella typhimurium as Gram-negative bacteria and their antifungal activities against Aspergillus fumigatus, and Geotricum candidum were evaluated using the agar well diffusion technique. The results indicated that these derivatives showed good antibacterial activity as judged by their high inhibition zone diameter and low minimum inhibition concentration. These derivatives are more potent against Gram-positive bacteria than against Gram-negative bacteria. The results also indicated that these derivatives have effective antifungal activity. The carboxy derivative exhibited the highest antimicrobial activity relative to the other derivatives. Their stabilizing efficiency is evaluated using thermogravimetric technique in nitrogen, and by the extent of discoloration as well as by the change in the molecular weight of the degraded polymer. The results reveal the greater stabilizing efficiency of these derivatives relative to dibasic lead carbonate (DBLC), cadmium-barium-zinc (Cd-Ba-Zn) stearate complex and di-n-octyltin bis (isooctylmercaptoacetate) (n-octyltin mercaptide, n-OTM) reference thermal stabilizers. This is well illustrated by the higher initial decomposition temperature, and lower rates both of weight loss and discoloration as well as decreasing in degree of chain scission of the polymer during degradation relative to those of the reference stabilizers. Moreover, the stabilizing efficiency is influenced by the nature of the substituent group in the aryl moiety of the phenyl urea part of these derivatives. While, the methyl derivative is characterized by a greater efficiency relative to those of the chloro and carboxy derivatives, the non-substituted derivative lies between these two cases.

Thermal Degradation Kinetics of Plasticized Poly (Vinyl Chloride) with Six Different Plasticizers

ABSTRACTPlasticized PVC formulated with different kinds of normally used plasticizers, including bis(2-ethylhexyl) phthalate (DOP), dioctyl terephthalate (DOTP), acetyl tri-n-butyl citrate (ATBC), acetyl trioctyl citrate (ATOC), trioctyl trimellitate (TOTM), and a new vegetable devived plasticizer, isosorbide ester (ID-37), were prepared by a melt blending method. The effect of plasticizer on the thermal degradation behavior of plasticized PVC was investigated by thermal gravimetric analysis (TGA). The activation energies were calculated by three well known methods, developed by Flynn-Wall-Ozawa (FWO), Friedman and Kissinger, respectively. The TGA conducted in N2 atmosphere showed that the type of plasticizer had an obvious influence on the thermal stability of plasticized PVC. It was found that the peak temperatures (TP) of the thermal degradation processes shifted to higher temperature with the increase of the heating rate, with two processes being shown. The activation energy of the first thermal decomposition process (E1), calculated by the Kissinger method, was between 118 and 130 kJ/mol, while the activation energy of the second thermal decomposition process (E2) was between 261 and 305 kJ/mol, except 499 kJ/mol for the PVC/TOTM formulation. The corresponding values of E1 and E2 obtained by the Flynn-Wall-Ozawa method were similar to the above data. E of the sample with TOTM also showed a higher value than the others; the results demonstrated that the PVC plasticized with TOTM was more thermally stable than with the others. The activation energies for certain conversion degrees were calculated by the Friedman method and the FWO method. The value of activation energy for 20%, 50%, and 80% conversion calculated by the Friedman method, exhibited an apparent difference from that calculated by the Flynn-Wall-Ozawa method; the results showed that the value of E obtained by the Friedman method was much more reasonable than that obtained by the Flynn-Wall-Ozawa method.

Optimal design, characterization, and thermal stability of bio-based Ca/Na/Zn composite stabilizer derived from myrcene for poly(vinyl chloride)

An adduct of myrcene and maleic anhydride (AMMA) was synthesized using a Diels-Alder reaction. The adduct was transformed into the corresponding sodium, calcium salt and zinc salts (Na-AMMA, Ca-AMMA, and Zn-AMMA) using a metathesis reaction. The chemical structures of AMMA, Na-AMMA, Ca-AMMA, and Zn-AMMA were confirmed with Fourier transform infrared spectroscopy (FTIR), Inductively coupled plasma-atomic emission spectrometry (ICP-AES), 1H and 13C nuclear magnetic resonance (1H NMR and 13C NMR), and X-Ray Diffraction (XRD). Mixed Ca/Na/Zn salts from AMMA provided thermal stabilization for poly (vinyl chloride) (PVC). The thermal and mechanical properties of the PVC samples were investigated using discoloration and Congo red tests, scanning electron microscopy analysis (SEM), thermal gravity analysis (TGA), TGA–FTIR analysis, thermal gravity-mass spectrometer analysis (TGA-MS), and dynamic mechanical analysis (DMA). Optimal design of the Ca/Na/Zn-AMMA formulation was studied. The application of Ca/Na/Zn-AMMA in an optimized formulation for a biobased, primary thermal stabilizer for PVC could significantly improve PVC thermal stability. The optimized Ca/Na/Zn-AMMA formulation had higher thermal stability, higher storage modulus, and lower glass transition temperatures than PVC blends without any thermal stabilizers and using commercial CaSt2/ZnSt2. The weights of the Ca/Na/Zn-AMMA samples were 33.3–75.0% that of CaSt2/ZnSt2, but provided higher thermal stability. Myrcene-derived Ca/Na/Zn-AMMA was shown to have strong potential as a primary PVC thermal stabilizer.

Thermal stabilization of polyvinyl chloride with traditional and naturally derived antioxidant and thermal stabilizer synthesized from tannins

The effects of tannin-cadmium complex on the thermal and oxidation stability of PVC were investigated. Tannin-cadmium complex has been successfully synthesized and characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray analysis techniques. Thermal degradation and thermal oxidation–degradation behaviors of PVC formulations obtained by thermal mixing method were evaluated by thermogravimetric analysis (TG) and differential scanning calorimetry (DSC) under inert and oxidizing atmospheres, respectively. The obtained results such as the onset, maximum and final degradation temperatures as well as the degradation rates from TG and DTG curves revealed that the tannin-cadmium has significant impact on the thermal stability of PVC. The experimental data of PVC thermal degradation obtained by DSC studies also clearly showed that the stabilizing efficiency of tannin-cadmium is superior to that of synthetic thermal stabilizer applied as reference. Due to the HCl scavenging and antioxidation activities of tannin-cadmium, the global thermal and morphological properties of PVC stabilized by this product proved the best in morphology and stabilization properties both against thermal and thermal oxidation–degradations.

Use of vitamin B1 for the surface treatment of silica (SiO2) and synthesis of poly(vinyl chloride)/SiO2 nanocomposites with advanced properties

In this study, silica (SiO2) nanoparticles (NP)s were used as fillers for the preparation of nanocomposite (NC) films. SiO2 NPs have a strong tendency to agglomerate. Therefore, the surface modification of SiO2 NPs was performed by vitamin B1 (VB1) as a biodegradable modifier. To obtain better dispersion into the polymer matrix, the process was accomplished under ultrasonic as a green route. After that, modified SiO2 NPs with different contents, incorporated into poly(vinyl chloride) (PVC) matrix and PVC/SiO2-VB1 NCs were prepared. TGA results indicated that the incorporation of SiO2-VB1 into the polymer matrix enhanced the thermal stability of pure PVC. Microscopic observations showed that SiO2-VB1 was homogeneously dispersed into the PVC matrix. According to UV–Vis spectra, the absorption of pure PVC increased in the presence of SiO2 NPs. The mechanical tensile test showed more flexibility for NC films in comparison to the pure PVC. Also, water contact angle analysis showed that the hydrophilicity of PVC increased in the presence of SiO2-VB1 NPs.

Design of green zinc‐based thermal stabilizers derived from tung oil fatty acid and study of thermal stabilization for PVC

ABSTRACTIn this study, a new type of mixed calcium (Ca) and zinc (Zn) thermal stabilizers was prepared and evaluated for poly(vinyl chloride) (PVC) thermal stabilization. The mixed stabilizers were based on the Ca and Zn salts of polycarboxylic acid derived from eleostearic acid—the dominant fatty acid of tung oil fatty acids. Eleostearic acid was converted to a 21‐carbon diacid (C21DA) and a 22‐carbon triacid (C22TA), respectively, which were subsequently turned into calcium (Ca) and zinc (Zn) salts. Thermal stability of PVC compounds was examined by thermogravimetric analysis (TGA), discoloration test, Congo red test, and thermal decomposition kinetics. In comparison, commercial mixed Ca/Zn thermal stabilizers composed of stearate salts (CaSt2/ZnSt2), were employed as controls. Because the salts of C21DA, C22TA and stearate have different metal contents, thermal stabilization effects were compared on the basis of both equal salt weight and equal metal ion content. It was noted that under both cases the long‐term thermal stability of the PVC samples followed the order of C21DA‐Ca/C21DA‐Zn > C22TA‐Ca/C22TA‐Zn > CaSt2/ZnSt2. The results suggest that the mixed Ca/Zn salts based on tung oil‐derived polycarboxylic acids have higher metal ion contents and cycloaliphatic structures and can effectively improve the thermal stability of PVC. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44679.

Preparation and characterization of zinc-mannitol complexes as PVC thermal stabilizers with high efficiency

A series of zinc oxide-mannitol complexes (Zn-Ma complexes) with different zinc contents were prepared, and the composition of Zn-Ma complexes was determined by atomic absorption spectroscopy and elemental analysis. The components of Zn-Ma complexes were separated by Soxhlet extraction and characterized by FT-IR. Dependence of the reaction extent on time at different temperature was investigated in order to optimize the preparation technology. The thermal stability of poly (vinyl chloride) (PVC) with Zn-Ma complexes was investigated by Congo red tests. The results showed that Zn-Ma complexes could significantly improve the thermal stability of PVC. The thermal stabilization mechanism and synergism effect of Zn-Ma complexes were also discussed.

A novel liquid Ca/Zn thermal stabilizer synthesized from tung-maleic anhydride and its effects on thermal stability and mechanical properties of PVC

A novel liquid Ca/Zn thermal stabilizer was synthesized from tung-maleic anhydride (TMA) as feedstock and evaluated for its stabilizing effects on poly (vinyl chloride) (PVC). First, N-(3-amino-benzoic acid) tung-maleamic acid (ABTMA) was prepared from the ammonolysis of TMA and para-aminobenzoic acid (PABA). Then its complex calcium salt (ABTMA-Ca) and zinc salt (ABTMA-Zn) were synthesized through a one-step method, and investigated by Fourier transform infrared spectroscopy and elemental analysis. ABTMA-Ca and ABTMA-Zn were separately treated with diethylene glycol monobutyl ether at 120 °C for 3 h to form liquid ABTMA-Ca (LABTMA-Ca) and liquid ABTMA-Zn (LABTMA-Zn). The effects of LABTMA-Ca/LABTMA-Zn, CaSt2/ZnSt2 and C36DA-Ca/C36DA-Zn on thermal stability of PVC were studied through Congo Red test, discoloration tests and dynamic thermal stability analysis. The LABTMA-Ca/LABTMA-Zn thermal stabilizer exhibit excellent long-term stability. Analysis of tensile and dynamic mechanical properties shows PVC samples stabilized with LABTMA-Ca/LABTMA-Zn and the other two Ca/Zn systems all display comparable strength, modulus and glass transition. A common stabilizing mechanism of LABTMA-Ca/LABTMA-Zn system and its radical mechanism were presented, respectively.