Study On The Synthesis And Application Of Pentaerythritol Ester As The Thermal Stabilizer For Poly (vinyl Chloride)

Pentaerythritol (PET) ester was an important kind of auxiliary thermal stabilizers forPoly (vinyl chloride), which was generally used with Zinc stearate/Calcium stearatecompounds. It was non-toxic and had the lubrication effect, which achieved variousrequirements of PVC processing process and had a wide application and research. PET anddipentaerythritol (DPET) had certain thermal stability in some cases. But their compatibilitywith PVC was bad, so we esterified PET and DPET with adipic acid to increase theircompatibility with PVC. In order to make the products have certain thermal stability,esterification degree was controlled by the ratio of raw materials in the process ofesterification, which will make the products have thermal stability and lubrication effect at thesame time.We esterified PET, DPET and MixPET with adipic acid respectively in this paper, andgot three kinds of eaters. The influence of the reaction factors was researched, such as theratio of raw materials, reaction temperature, reaction time, type of the catalyst and quantity ofthe catalyst additive. Fourier transform infrared spectroscopy (FTIR) and mass spectrometry(MS) were used to study the structure of the products. The melting point of PET and DPETwas262℃and220℃respectively, which were higher than the processing temperature ofPVC (180℃). When DPET and PET were mixed at the melting point, they could form a kindof eutectic structure, which could reduce the melting point of MixPET. So we could controlthe melting point of MixPET ester by controlling the ratio of PET and DPET. Differentialscanning calorimeter (DSC) was used to study the melting temperature of these three kinds ofproducts, which showed that with the increase of the quantity of AA, the melting points ofproducts were reduced. In MixPET system, with the increase of the quantity of PET, themelting points of products reduced markedly. Other factors on melting point of the productswere not obviously. DSC analysis showed the best ratio of PET and AA was2/0.7for mole,the best ratio of DPET and AA was2/1.3for mole. In MixPET system, when the ratio ofDPET, PET and AA was41/32/27for quality, the melting point of the product was151.1℃,which was33.7℃lower than dipentaerythritol adipic acid esters of184.8℃. DSC andHAAKE rheometer were used to determine the appropriate reaction conditions. Theconditions could not only reduce the melting points of the products as far as possible, but alsohas the good thermal stability effect and processing properties.In order to make sure the products could not decompose before the PVC processing temperature (180℃), thermogravimetric analysis (TG) were used to study the stability of theproducts. Though these products had different esterification degrees, they were very stable.Their decomposition temperature was245℃,355℃and285℃respectively through TGanalysis, which were far higher than PVC processing temperature. HAAKE rheometer, Congored experiment and hot oven aging experiment showed that the products of MixPET hadbetter thermal stability effect than PET and DPET, which was more suitable to the processingof PVC.