Optimization of the curing conditions of PVC plastisols based on the use of an epoxidized fatty acid ester plasticizer

The use of an epoxidized fatty acid ester (EFAE) as a natural-based plasticizer for plasticized PVC (P-PVC) has been evaluated in this work. The effect of the curing conditions has been studied by following several test techniques such as mechanical properties, thermal behavior, color changes, solvent migration and microstructure. Different curing processes at isothermal conditions (ranging from 160 °C to 220 °C) have been carried at curing times in the 6–16 min range. The optimum mechanical response (tensile strength values in the 9–10 MPa range and elongation at break close to 250%) is obtained for plastisols cured at 200 and 220 °C for 12 and 8 min curing times, respectively. These curing conditions also offer the lowest migration in n-hexane (lower than 11%) which is indicative of plasticizer total absorption. Furthermore, the use of these curing conditions does not lead to thermal degradation as confirmed by color measurements.     

Thermal and mechanical behaviour of flexible poly(vinyl chloride) mixed with some saturated polyesters

Four saturated polyesters poly(hexamethylene adipate), poly(ethylene adipate), poly(hexamethylene terephthalate) and poly(ethylene terephthalate) were prepared. The resulting materials were characterized by IR and ¹H NMR, end group analysis and gel permeation chromatography. The effect of blending these polyesters (5 and 10%) with poly(vinyl chloride) (PVC) in the melt was investigated in terms of changes in the thermal behaviour of PVC by studying the weight loss after 50 min at 180 °C, colour changes of the blend before and after aging for one week at 90 °C, the variation in glass transition temperature and the initial decomposition temperature. The results gave proof for the stabilizing role played by the investigated polyesters against the thermal degradation of PVC. The best results are obtained when PVC is mixed with 5% aliphatic polyesters rather than with aromatic ones. This is well illustrated not only from the increase in the initial decomposition temperature (IDT), but also from the decrease of % weight loss and from the lower extent of discolouration of PVC, which is a demand for the application of the polymer. It was also found that blending PVC with 5% of the four investigated polyesters before and after aging for one week at 90 °C gave better mechanical properties even than that of the unaged PVC blank.     

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.     

Structures and Mechanical Properties of PVC／Na^＋—Montmorillonite Nanocomposites

Poly(viyl chloride)/Na^ -montmorillonite(PVC/MMT)nanocomposites with different MMT contents were prepared via melt blending.Wide-angle X-ray diffraction(WAXD)and transmission electron microscopy(TEM)were used to characterize the structures.Effects of MMT content on the mechanical properties were also studied.It is found that PVC molecular chains can intercalate into the gallery of MMT layers during melt blending process,the stiffiness and toughness of the composites are inproved simultaneously within 0.5-7wt% MMT content,and the transparency and mechanical properties decrease as MMT conten further increases.     

力化学降解对聚氯乙烯加工流变行为的影响

采用Brabender塑化仪和毛细管流变仪研究了经力化学降解制得的聚氯乙烯(PVC)的加工流变行为。结果表明,降解的PVC塑化时间比未降解的PVC明显缩短,塑化速度和熔化效率也明显加快,熔体粘度及玻璃比温度降低。     

热稳定剂对PVC紫外光老化过程中微观结构及宏观性能演变的影响

通过UV-Vis、FTIR、DSC、以及色差、力学性能的测试表征,实时追踪分析了在紫外光老化过程中,含Pb、Sn以及Ca-Zn热稳定剂的PVC体系微观结构和宏观性能的演变过程.结果表明,在相同光老化条件下,PVC/Pb、PVC/Sn和PVC/Ca-Zn体系的微观结构变化规律基本一致,过程中主要的化学反应是,大分子吸收光能后,发生脱HCl生成共轭双键的反应、生成羰基的氧化反应、交联反应和降解反应;不同热稳定剂的作用,主要表现在对于微观结构变化的幅度和动力学过程的影响不同.相应地,3种体系的外观色差和力学性能的变化规律也相似,但色差的变化程度和速度以及老化后力学性能的保持率因所含热稳定剂的不同而不同,其中含Sn体系的颜色稳定性最好,含Pb体系的力学性能保持率最高。     

聚氯乙烯结构缺陷和热不稳定性之间关系的研究 2.各种结构缺陷含量和热脱氯化氢速率之间的关系

本工作采用溴加成法、酚解法、FTIR法及臭氧裂解法分别测定了五种不饱和蒸气压下聚合的PVC样品(u-PVC)和五种商品PVC样品(s-PVC)的总双键、总不稳定氯、孤立双键和内部双键的含量.通过研究结构缺陷和PVC的平均分子量及脱HCl速率的相互关系,揭示了不饱和总双键值,总不稳定氯和孤立双键含量彼此的相关性是建立在它们分别与1/M_n的相关性基础之上,从而得出了这三种定量值测得的主要都是端基烯丙基氯结构.根据三者对脱HCl速率的良好线性相关性,首次提出了端基烯丙基氯结构在HCl催化作用下异构化成内部烯丙基氯从而成为脱HCl速率主要原因的机理.     

Synthesis of an efficient bio-based plasticizer derived from waste cooking oil and its performance testing in PVC

In order to develop an efficient and sustainable plasticizer, the waste cooking oil and malic acid were used as the main raw materials in this study to synthesize a bio-based plasticizer (acetylated-fatty acid methyl ester-malic acid ester, AC-FAME-MAE) by environment-friendly methods, and the structure was characterized by FTIR and ¹H NMR. The properties of the poly (vinyl chloride) (PVC) with AC-FAME-MAE were tested and compared with those of the PVC plasticized with DOP (di-2-ethylhexyl phthalate) and EFAME (epoxy fatty acid methyl ester), respectively. The results of tensile test, TGA and leaching test showed that the mechanical properties, thermal stability and overall solvent resistance of PVC films with AC-FAME-MAE were significantly better than those of PVC films plasticized by DOP or EFAME. From the results of DMA, the plasticized efficiency of AC-FAME-MAE was as good as DOP. The application of AC-FAME-MAE has higher safety in the food industry based on the results of food simulation fluids experiment.     

Hydroxylbenzylthioethers as novel organic thermal stabilizers for rigid PVC

An investigation was carried out on the performances of hydroxylbenzylthioethers employed as organic thermal stabilizers for rigid poly(vinyl chloride). The efficiency of these compounds as thermal stabilizers was evaluated by using Haake polydrive mixer and TGA. The stabilizing efficiency was compared with Ca-Zn soap and methyltin stabilizer. Hydroxylbenzylthioethers exhibit greater efficiency than both of these stabilizers. This is attributed to the ability of these compounds to prevent the formation of polyene sequences. The hydroxylbenzylthioethers-stabilized PVC showed a slightly lower glass transition temperature (T_g) in comparison with the original PVC. Hydroxylbenzylthioethers and epoxidized soybean oil (ESBO) exhibit synergistic effect on the stabilizing effect, when the mass ratios of ESBO to hydroxylbenzylthioethers are less than 0.5.     

Thermal degradation of PVC synthesized with a titanocene catalyst II. Complementary isothermal results

The use of an isothermal degradation method on metallocene produced PVC and commercial PVC, under nitrogen and air atmospheres, reveals more details about degradation routes. Without regard to the polymer origin, the hydrochloric acid release occurs in two steps, which are reflected in molecular weight only under a nitrogen atmosphere; otherwise, the oxygen appears to be included in the scission/crosslinking process. On the one hand, Met PVC has unsaturations from its synthesis, producing a faster HCl release compared to Com PVC; consequently, its degradation resistance is lower. On the other hand, Com PVC has more oxidized species and has a natural tendency to include more of them. Surface area seems to have an important effect and is directly related to the rate of hydrochloric acid release. The latter is not supported by the chain oxidation mechanism, making the effect of the applied atmosphere more critical to the results obtained from the degradation experiments.     

聚氯乙烯结构缺陷和热不稳定性之间关系的研究——Ⅰ.在单体不饱和蒸汽压下聚氯乙烯的合成及其热稳定性与分子量之间的关系

聚氯乙烯(PVC)容易发生脱氯化氢的热降解。研究者普遍认为,这是由于PVC分子链中存在结构缺陷而引起的。对究竟何种结构缺陷是引起PVC热不稳定的主要根源这一重要问题,虽然已有许多研究者进行过研究,但由于他们得到的结果往往各不相同,因而迄今未能达到一个明确一致的结论。如Minsker认为羰基烯丙基氯结构是引发脱HCl的主要原因。但Starnes却持相反意见。Hjertberg在其报告中指出叔氯     

A simple and green route to transparent boron nitride/PVA nanocomposites with significantly improved mechanical and thermal properties

A simple and green method is developed to prepare hexagonal boron nitride(h-BN)/poly(vinyl alcohol) (PVA) nanocomposites by using water as a common solvent of h-BN nanosheets and PVA.The obtained h-BN/PVA nanocomposites are highly transparent,and have significantly improved mechanical and thermal properties.They may outperform nano-clay and nano-alumina/PVA nanocomposites as flexible optoelectronic devices,optical windows and heat-releasing materials operated in oxidative or corrosive environment.     

Performance testing of a green plasticizer based on lactic acid for PVC

In order to develop alternative green plasticizers, a bio-based plasticizer, acetylated lactic acid 1,4-cyclohexanedimethyl ester(ALCH), with novel molecule geometry was synthesized from l-lactic acid and characterized by FTIR, ¹H NMR and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). The prepared ALCH was mixed with poly(vinyl chloride) (PVC) as plasticizer and the results indicated that the PVC films plasticized by ALCH have better migration and volatility stability than acetyl tributyl citrate (ATBC). In addition, ALCH could endow PVC products with excellent performance of strength, elongation and elasticity. With the substitution of ALCH for ATBC, glass transition temperature (Tg) of PVC films decreased gradually from 61.3°C to 55.0 °C. The self-polymerization of lactic acid gives ALCH better plasticizing effectiveness than ATBC.     

Degradation behavior and application of recycled PVC sheet made of floor sheet for railway vehicle

A floor sheet made of plasticized poly(vinyl chloride) (PVC) is used as interior material for railway vehicle. Some of the floor sheets mainly used in Express and Shinkansen vehicles were layered by vulcanized surface to protect against the fire. Therefore, these floor sheets have been considered as inappropriate material for recycling. In this paper, some varieties of recycled sheets made of these floor sheets have been studied with respect to a long-term stability which is necessary for practical application. Through the weathering test, these recycled sheets indicated suitable mechanical properties for long-term outdoor use; however, at the beginning of weathering test, the elongation was reduced by the rapid flow out of plasticizer. The mechanical strength was closely related to the plasticizer concentration. Based on the plasticizer concentration, the tensile strength could be estimated without dependence of specimen preparations and the slope of the elongation was related to the content of the floor sheet. To prevent flowing out of plasticizer, virgin PVC was laminated to the surface of recycled sheet. The laminated sheet was set up at the outdoor to be used as an anti-weed sheet. For more than five years, the laminated sheet has kept on preventing overgrowth of weed and flow out speed of plasticizer has decreased by the effect of virgin PVC lamination. It is presumable that the laminated sheet was estimated to be used as the anti-weed sheet for more years.     

Application of high resolution thermogravimetry to the study of thermal stability of poly(vinyl chloride) resins

The influence of microstructure on thermal degradation behaviour was studied in five samples of pure poly(vinyl chloride) (PVC) obtained at different polymerisation temperatures. Tacticity of the samples was characterized by Fourier transform infrared spectroscopy (FTIR), and their thermogravimetric behaviour was measured by high resolution (Hi-Res™) TGA. This technique is able to detect two independent weight loss steps in the dehydrochlorination. The relative contribution of these two steps responds to different syndiotacticity tendency of PVC samples, in accordance with FTIR results.     

End-capped biobased saturated polyesters as effective plasticizers for PVC

In this work, flexible PVC formulations were prepared using biobased end-capped saturated polyesters (SPs). The SPs were end-capped for the first time with long alkyl chains (both branched (2-tetradecyloctadecan-1-ol, TDOD) and unbranched (octanol, Oc) aiming to increase the compatibility with PVC matrix, free volume and reduce migration. The properties of PVC samples plasticized with the SPs were compared with a PVC sample plasticized with dioctyl terephthalate (DOTP). A significant decrease in the T_g (60 °C <ΔT_g<80 °C) of PVC plasticized films was observed, and the samples plasticized with the SP end-capped with Oc presented an elongation at break (ε) value very close to the DOTP-plasticized PVC. Migration tests revealed that PVC plasticized with SPs have lower amount of extractables, especially those using Oc end-capped SP. Also, the decrease of thermomechanical properties of the samples plasticized using SPs is almost negligible when compared with the samples plasticized with DOTP. Overall, the results showed that the SP end-capped with Oc is a reliable alternative to DOTP.     

Synthesis of a bio-based plasticizer from oleic acid and its evaluation in PVC formulations

The bio-based plasticizers have been extensively developed due to their high compatibility and low toxicity. In this study, the bio-based plasticizers of methyl 10-(2-methoxy-2-oxoethansulfonyl) octadecanoate (MDA) and ethyl 10-(2-ethoxy-2-oxoethanesulfonyl) octadecanoate (EDA) were synthesized from the oleic acid and thioglycolic acid and characterized by ¹HNMR and FT-IR. The prepared materials were applied as plasticizers in Poly(vinyl chloride) (PVC) and their properties were compared with the commercial plasticizer, Bis(2-ethylhexyl) phthalate (DOP). The viscosities of prepared plastisols from novel designed plasticizers were lower than DOP. The results of mechanical properties showed that the synthesized plasticizers of MDA and EDA have the ability of plasticizing effects similar to DOP on PVC. Thermogravimetric analysis (TGA) indicated that both MDA and EDA have higher thermal stability than DOP. Two polar ester as well as polar sulfone groups in the chemical structure of MDA and EDA led to lower migration, volatility and exudation than DOP.     

Effect of new melamine-terephthaldehyde resin modified graphene oxide on thermal and mechanical properties of PVC

In this study a new melamine-terephthaldehyde resin modified graphene oxide was synthesized and used as a reinforcement of poly(vinyl chloride) (PVC). Characterization, morphology, thermal and mechanical properties of the nanocomposites were examined by means of attenuated total reflectance-Fourier transform infrared spectroscopy, X-ray diffraction, field emission-scanning electron microscopy, thermogravimetric analysis, differential scanning calorimeter and tensile properties. The first hydrochloric acid releasing data of poly(vinyl chloride) was removed by incorporation of the modified graphene oxide as compare to the neat polymer. The temperatures at 2 wt% losses, main decomposition temperatures, maximum decomposition temperatures, also shift to higher temperature in the corresponding nanocomposites as compared to the neat PVC. The tensile strength and elongation at break of the nanocomposite films was increased as compared to the neat PVC. The interesting results in crystallinity of PVC were observed with adding 5 wt% of the modified graphene oxide.     

可交联PVC的合成及其交联反应

N,N-二乙基二硫代氨基甲酸钠(铜试剂,简称NasR)取代PVC链中的部分氯原子,制得不同官能度的功能高分子PVC-SR.在热的作用下,实现了PVC-SR的自交联和PVC-SR/NBR共混体系的共交联.研究了温度、铜试剂用量对取代反应的影响及PVC-SR官能度对交联反应硫化曲线、产物的凝胶含量、玻璃化温度、拉伸性能和压缩永久变形的影响,并初步探讨了交联反应机理.     

含环氧基的丙烯酸酯弹性体的合成及其对聚氯乙烯改性研究

以丙烯酸丁酯（ＢＡ），甲基丙烯酸甲酯（ＭＭＡ）和甲基丙烯酸缩水甘油酯（ＧＭＡ）为原料，通过分段乳液聚合，合成了一系列具有不同组成结构的三元共聚物—Ｐ（Ｂ—Ｍ—Ｇ）弹性体，并对此弹性体改性的ＰＶＣ的抗冲击性能进行了系统研究．结果表明：改性剂组成结构的变化对改性体系的冲击性能有较大影响，改性ＰＶＣ的冲击性能最高可达７９ｋＪ／ｍ２．动态力学及ＳＥＭ实验表明，ＰＶＣ与改性体系系部分相容的共混体系，其断裂行为是明显的韧性断裂特征．本文还对改性体系的力学性能进行了研究．