Heteroatom Modified Oil/Dipentene-Based Ca/Zn Thermal Stabilizers For PVC:Preparation And Performance Study

With the ever increasing environmental protection requirement,highly efficient,environment friendly and muti-functional thermal stabilizers have attracted much attention and become the research focus.Although the traditional calcium and zinc salts as stabilizer are environmental and inexpensive,it is easy to cause"zinc burning"in a short time.In this study,the renewable woody oil,rosin and its derivatives were used as the raw materials to synthesis a series of nitrogen and phosphorus groups-containing Ca/Zn thermal stabilizers for poly?vinyl chloride??PVC?by the Diels-Alder reaction,epoxidation reaction and replacement reaction of congugated double bonds and hydroxyl group etc.Moreover,nitrogen groups-containing ZIF-8was added to CaSt₂/ZnSt₂ and used as PVC Ca/Zn composite thermal stabilizers.Besides,the relationship between the structures and properties were studied and discussed in detail in this work as well.This work offered theoretical basis and references for the efficient utilization of natural renewable resources and the sustainable progress of the industry of environmental and efficient PVC thermal stabilizer.The specific contents are the following five parts:1.In this work,single amide-containing tung-oil-based and dipentene-based carboxylic acid?ABDPMA and ABTMA?were prepared by the Diels–Alder addition of dipentene and tung-maleic anhydride?TMA?with maleic anhydride,and the ammonolysis reaction with para-aminobenzoic acid?PABA?respectively,and subsequently converted into corresponding zinc soap?ABDPMA-Zn,ABTMA-Zn?or calcium soap?ABDPMA-Ca,ABTMA-Ca?.Their chemical structures were confirmed by Fourier transform infrared spectrometry?FTIR?and inductively coupled plasma atomic emission spectroscopy?ICP-AES?.Thermal stabilities of PVC/ABTMA-Ca/ABTMA-Zn and PVC/ABDPMA-Ca/ABDPMA-Zn were determined using Congo red test,discoloration test,ultraviolet-visible spectroscopy analysis and thermogravimetric analysis.Thermal stabilizing effects of ABDPMA-Ca/ABDPMA-Zn and ABTMA-Ca/ABTMA-Zn were compared with C36DA-Ca/C36DA-Zn?C36DA:dimer fatty acid?,and CaSt2/ZnSt2?St:stearic acid?.Thermal stabilities of poly?vinyl chloride??PVC?compounds were determined using Congo red test,discoloration test,ultraviolet-visible spectroscopy analysis and thermogravimetric analysis.Dynamic mechanical properties of the PVC compounds were also studied.PVC/ABDPMA-Ca/ABDPMA-Zn has the longest static thermal stability time?T_s,71 min 48 s?and its zinc burning time can be retarded over 90 min.ThatmensABDPMA-Ca/ABDPMA-Znexhibitexcellentlong-termstability.ABDPMA-Ca/ABDPMA-Zn could more significantly enhance the long-term thermal stability of PVC,as indicated in the Congo Red test,thermal aging test,UV-Vis spectroscopy and thermogravimetric analysis.The reason may be attributed to the combined effect of Ca/Zn stabilizing mechanism and radical mechanism.Moreover,a better dispersion of ABDPMA-Ca/ABDPMA-Zn in PVC contributes to the high thermal stability.Dynamic mechanical analysis?DMA?results shown ABDPMA-Ca/ABDPMA-Zn has better plasticization performance for PVC than that of the other compared stabilizers.2.Binary amide-containing tung-oil-based carboxylic acid?AETMA and APTMA?were prepared by the the ammonolysis reaction of TMA with ethidene diamine?ED?and p-phenylenediamine?PPD?with TMA,respectively,and subsequently converted into corresponding liquild zinc soap?LAETMA-Ca,LAPTMA-Ca?or calcium soap?LABTMA-Zn and LAPTMA-Zn?.Their chemical structures were confirmed by FTIR,¹H nuclear magnetic resonance?NMR?and ICP-AES.LAETMA-Ca/LAETMA-Zn and LAPTMA-Ca/LAPTMA-Zn were both used as thermal stabilizers of PVC and investigated using Congo red test,thermal aging test,ultraviolet-visible spectrometry,thermal gravimetric analysis?TGA?,TGA-IR,and TGA-mass spectrometry?MS?.PVC/ABDPMA-Ca/ABDPMA-Zn has the longer T_s?73 min 04s and 70 min 04 s?and its zinc burning time can be retarded over 90 and 80 min,respectively.That means The LAPTMA-Ca/LAPTMA-Zn exhibits better long-term stability than other stabilizers.The mechanism underlying the stabilizing action of LAPTMA-Ca/LAPTMA-Zn is suggested.3.Hydroxyl and nitrogen rich groups-containing tung-oil-based Ca/Zn?Ca-HTMA-1,Zn-HTMA-1,Ca-HTMA-2 and Zn-HTMA-2?and polyol thermal stabilizers?HTMA-1 and HTMA-2?were successfully synthesized from TMA and melamine as feedstock.The order of co-stabilizing effect of the four auxiliary stabilizers with the same content of CaSt₂/ZnSt₂ is as follows:HTMA-2?the best?>HTMA-1>HHTT>PER,revealing a better synergistic effect between HTMA-2 and CaSt₂/ZnSt₂..That means CaSt₂/ZnSt₂/HTMA-2 gives better long-term stability for PVC.Then the self-made polyol auxiliary stabilizer was combined with self-made calcium zinc or CaSt2/ZnSt2.The results show that CaSt2/Zn-HTMA-2/HTMA-2 displays the best thermal stability for PVC.The superior performance is attributed to the synergistic effect of CaSt2,Zn-HTMA-2 and HTMA-2,which is originated from the simultaneous introduction of hydroxyl and nitrogen rich groups into the Zn-HTMA-2 and HTMA-2 structures.Besides the better stabilization performance,CaSt₂/Zn-HTMA-2/HTMA-2 also displays comparable plasticization performance for PVC compared with other stabilizers.A possible stabilizing mechanism of PVC/CaSt₂/Zn-HTMA-2/HTMA-2 system was presented.4.Phosphate ester groups-containing ricinoleic acid-based Ca/Zn?LPPRA-Ca and LPPRA-Zn?stabilizer was successfully synthesized from ricinoleic acid?RA?as feedstock and used as thermal stabilizers for PVC.These thermal stabilizers were characterized by FTIR,¹H NMR and ICP-AES.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,TGA,TGA-IR,and TGA–MS.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.5.A zeolitic imidazolate framework material?ZIF-8?was prepared from2-methylimidazole as as feedstock and characterized by a series of methods.It was used as a separate PVC stabilizer or by mixing with CaSt2/ZnSt2 as a complex stabilizer.It was found that the addition of ZIF-8 gave better initial color stability and long-term thermal stability.Moreover,its zinc burning time can be retarded.That means CaSt₂/ZnSt₂/HTMA-2 gives better long-term stability for PVC.The study finds that this probably is because ZIF-8 could further complex with ZnCl₂ to minimize the“zinc-burning”.Clearly,the long-term stability of PVC can be promoted by increasing the ZIF-8 content in CaSt₂/ZnSt₂/ZIF-8,which reveals a synergistic effect between ZIF-8 and CaSt2 or ZnSt2.Furthermore,the ZIF-8/ZnSt2 stabilizer with a mass ratio of 2/1 significantly prolonged the T_s to about 128.92 min,and evidently improved the initial color of PVC as well.Moreover,the PVC strips containing ZIF-8/ZnSt2did not happened“zinc-burning”within 120 min.The superior performance was attributed to the synergistic effect of ZIF-8 and ZnSt₂.Besides,PVC/ZIF-8/ZnSt₂ exhibits slightly lower breaking elongation compared with the controls.However,it still remains at a high level.