增塑剂对旋转模塑用PVC增塑糊性能的影响

通过增塑剂种类及用量对旋转模塑用聚氯乙烯(PVC)增塑糊粘度及其粘度稳定性、脱气性能、凝胶化性能的影响及温度对凝胶化性能的影响进行了研究。结果表明:选择自身粘度较小且溶剂化能力较弱的增塑剂及随增塑剂用量增加,PVC增塑糊粘度下降、粘度稳定性逐渐变好,有利于PVC增塑糊的排气性能提高,延长PVC增塑糊的凝胶化时间。通过调节加热温度及时间可在一定范围内有效控制凝胶化过程,以期获得制品所需性能。     

Optimization of plastisol processes by dynamic mechanical analysis

Dynamic mechanical analysis (DMA) can be a particularly useful tool for studying PVC plastisol manufacturing processes. DMA temperature sweeps are uniquely able to characterize plastisol gelation and fusion behavior under low shear stress conditions that are similar to conditions found in many commercial plastisol processing operations. Dynamic mechanical analysis is also well‐suited for studying plastisol melt viscosities at low shear rates such as might be encountered in a flexible PVC foaming process or rotomolding process. Likewise, DMA rate sweeps or strain sweeps can give insights into self‐association and flow properties in a plastisol which ordinary viscometers cannot provide. J. VINYL ADDIT. TECHNOL., 13:151–154, 2007. © 2007 Society of Plastics Engineers     

Processability of PVC plastisols containing a polyhydroxybutyrate‐polyhydroxyvalerate copolymer

Plastisols based on polyvinyl chloride (PVC) can be processed by different techniques; their processability markedly depends on their flow properties and gelation/fusion processes. Classically, PVC has been the only polymer present in plastisol formulations. The present work explored the possibility of adding polyhydroxyalkanoates (PHAs), a type of biopolymer that, according to previous work, exhibits a good miscibility with PVC processed by other techniques (internal mixer and compression molding). The influence of PHA particles on flow properties, gelation‐fusion processes, tensile strength, hardness, and processability by rotomolding was evaluated. Although the biopolymer markedly increased the viscosity of PVC plastisols and caused a decrease in tensile strength in processed specimens, formulations including 20% by weight of biopolymer presented a good thickness distribution in rotomolded items, an elongation at break of around 300%, and an ultimate tensile strength of around 6–7 MPa. J. VINYL ADDIT. TECHNOL.,, 2012. © 2012 Society of Plastics Engineers     

高填充粉煤灰PVC复合发泡板材的制备及性能

以偶氮二甲酰胺(AC发泡剂)、Zn O和Na HCO3复合体系作为发泡剂,采用模压发泡的方法制备高填充粉煤灰聚氯乙烯(PVC)复合发泡板材,确定复合发泡剂的最优配比及其在复合发泡板材中的最佳用量,并对其性能进行了研究。采用发气量测定、热重/差示扫描量热(TG/DSC)分析对AC发泡剂进行了改性研究,选出分解温度满足加工条件的复合发泡剂。添加不同份数的复合发泡剂制备PVC复合发泡板材,用扫描电子显微镜(SEM)分析其断面,测试板材的冲击强度及弯曲强度。实验结果表明,当AC发泡剂、Zn O和Na HCO3的配比为2∶1∶1.5时,最大发气量为213 m L/g,分解温度区间为165~177℃,满足PVC发泡板材加工。当复合发泡剂添加量为6份时,力学性能达到最佳,弯曲强度为17.63 MPa,冲击强度为21.88 k J/m2,达到国家硬质聚氯乙烯低发泡板材的标准;粉煤灰填充量高达61.16%。     

DSC study of foamable poly (vinyl chloride‐co‐vinyl acetate) plastisols of different commercial plasticizers

In this article the characterization of the thermal behavior of foamable PVC (Poly (vinyl chloride)) plastisols from 20 different plasticizers has been studied by differential scanning calorimetry (DSC). The interactions between the resin and the plasticizer as well as the decomposition of the azodicarbonamide (ADC)—the chemical blowing agent (CBA) used—have been analyzed. The latter process is of crucial importance for the knowledge of plasticized PVC flexible foam formation. Clear effects of the chemical nature of the plasticizers and their molecular weight (M_w) have been observed, both in the interactions (swelling and early stages of gelation) between the resin and the plasticizer, as well as in the temperature of the ADC decomposition and the shape of the DSC peak. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Nanoscopic characterization of a plastisol gelation and fusion process utilizing scanning electron microscopy and atomic force microscopy

Understanding the physical properties associated with the gelation and fusion of a PVC plastisol will help to improve process efficiency. Plastisol gelation and fusion were characterized by using both scanning electron microscopy (SEM) and atomic force microscopy (AFM) and were compared with the tensile properties developed at various temperatures. Both SEM and AFM showed good agreement during the early stages of gelation. However, AFM continued to show particle boundaries during the latter stages of gelation and fusion that provided a more nearly accurate comparison with the resulting tensile properties. J. VINYL ADDIT. TECHNOL., 2008. © 2008 Society of Plastics Engineers.     

Fusion behavior of plastisols of PVC studied by ATR-FTIR

The behavior of PVC plastisols during gelation and fusion was studied by the ATR-FTIR technique (Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy). DBP, DOP, and DIDP, three common phthalate plasticizers for PVC, were used in plastisols formulations. Three heating rates—5, 10 and 15°C/min—and formulations with different plasticizer concentrations were studied. The IR spectra of a plastisol coincides with the IR spectra of the plasticizer except for the bands at 1435 and 613 cm^?1 from the PVC (CH₂ wagging and C—Cl stretching, respectively). When the plastisol is heated, a progressive decrease of the plasticizer bands areas can be observed, while bands from PVC increase their intensity, probably because of the adsorption of the plasticizer by the resin. On cooling, the area of all bands follows the same path as when heating, but the paths separate at a certain temperature, showing the irreversible nature of this process. The analysis of the band at 1280 cm^?1 (C(O)—O from plasticizer) during heating and cooling, shows that the temperature of separation areas (T_s) takes place at temperatures coherent with plasticizer compatibility. Studies at different heating rates and different plasticizer content are in good agreement with results using other techniques, available in the literature.     

PVC型材边角料回收再利用

研究了回收聚氯乙烯(PVC)型材边角料对PVC材料力学性能、热稳定性、流变性能及密度的影响。力学性能结果表明,PVC型材边角料用量10份时试样综合力学性能较好,拉伸强度为45.3 MPa,冲击强度为4.3 kJ/m2。PVC边角料热稳定性较好,几乎可以和PVC材料保持一致,从而保证加工后材料的热稳定性。流变性能测试结果表明,随着回收PVC边角料加入量的增多,塑化扭矩几乎没有增大,平衡扭矩数值变化不大,但到达平衡扭矩的时间变长。总体而言,加入回收PVC边角料对材料流变性能影响不大。通过加入不同含量的发泡剂偶氮二甲酰胺,测试结果表明,对含回收PVC边角料的发泡材料,发泡密度是影响材料力学性能的主要因素。     

Changes in rheological properties of polyvinyl chloride plastisols with storage time

In this study, the changes in the rheological curves of polyvinyl chloride (PVC) plastisols with increasing storage time and the factors affecting these changes were studied. The results show that with increasing storage time, all the “viscosity–temperature” and “viscosity–time” rheological curves of PVC plastisols exhibit nonnormal distribution change trends, that is, the viscosity first decreases, and then changes from slow increasing to rapid increasing, forming a shoulder peak, reaches to the maximum value and gradually decreases. With increasing storage time, the complex viscosities of PVC plastisols increased generally in the first, the second, and the fourth stages, and the gelation process shortened in the third stage. The first and second stages of the viscosity changes reflect the “time–temperature” equivalence principle of PVC plastisol in suspension stage. However, the maximum viscosity of PVC plastisol corresponding to temperature Tη_max does not change with increasing storage time.     

Effect of zinc stearate and/or epoxidized soybean oil on gelation and thermal stability of PVC‐DOP plastigels

The effects of zinc stearate (ZnSt₂) and/or epoxidized soybean oil (ESO) on mechanical properties and on thermal stability of plastigels obtained from polyvinylchloride (PVC) and dioctylphthalate (DOP) plastisols were studied using calorimetric, spectroscopic, and tensile‐testing techniques. Plastigels having 2.5 or 5.0 part ZnSt₂ and/or 5 part ESO and 60 part DOP per 100 part PVC (phr) were gelled by heating at 140°C. The tensile strength of plastigels with no additive and having 5 phr ZnSt₂, ESO, and both ZnSt₂ and ESO were 0.79, 0.46, 0.98, and 0.58 kN/cm², respectively. The decrease of tensile strength of plastigels with ZnSt₂ could be explained by the existence of ZnSt₂ in the solid phase in plastigels, as shown by differential scanning calorimetry (DSC). ESO helped better fusion of the plastisols without any additive and with ZnSt₂. Higher tensile strengths of ESO containing plates indicated more complete gelation of the plastisols. The thermal stability of plastigels in terms of color and their yellowness index (YI) were higher for ZnSt₂ containing plastigels. Conjugated polyene concentrations were calculated from UV spectra of the films heated at 140°C. The reaction rate constant of the dehydrochlorination of PVC changed with the additives. Faster dehydrochlorination than control gels occurred in gels having ZnSt₂ at long heating times due to the autoaccelerating effect of ZnCl₂ formed by reaction of eliminated hydrogen chloride and ZnSt₂. Organic acid formation reaction between ZnSt₂ and HCl formed by dehydrochlorination is investigated from the IR band at 1540 cm⁻¹ and 3400 cm⁻¹ during heating of the plastigel films. A synergistic effect of ESO and ZnSt₂ was observed when the mechanical strength and heat stability were considered together. Although ESO increased tensile strength, ZnSt₂ increased thermal stability of the plastigels at early times when they were present simultaneously in plastisols. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2488–2498, 1999     

Molecular modeling of polymer structures and properties,Bruce R. Gelin. Carl Hanser Verlag,Munich, Vienna,New York, 1994. pp. vii + 168, price DM98.00. ISBN 1-56990-125-2

The dynamic and isothermal gelation points of poly(vinyl chloride) (PVC) were determined using spectrophotometric and viscometric techniques. Four different PVC samples, with viscosity-average molar masses of 70 000, 90 000, 106 000 and 141 000, were used. The dynamic thermal gelation points of PVC samples heated to temperatures between 120 and 280°C were found to be between 232 and 236°C. Isothermal gelation times of PVC (M?_v = 106 000) heated at 170, 180, 190 and 200°C were determined as 345, 177, 78 and 37 min., respectively. An inverse relationship between the tendency to dynamic and isothermal gelation with increase in molar mass of PVC samples was found. On the other hand, the tendency to isothermal gelation of PVC increases with raising temperature.     

Synergistic effect of metal soaps and natural zeolite on poly(vinyl chloride) thermal stability

The synergistic effect of metal soaps (zinc stearate and calcium stearate) and/or natural zeolite (clinoptilolite) on PVC thermal stability was investigated. For this purpose, PVC plastisol was prepared by mixing poly(vinyl chloride) (PVC) and dioctyl phthalate (DOP) and stabilized with different amounts of metal soaps and zeolite. Kinetic studies of dehydrochlorination at 140 and 160°C were done for unstabilized and stabilized PVC plastigels using 763 PVC Thermomat equipment. The stabilizing effect of zeolite on the increase in the induction period of the sample was considered to result from the absorption of HCl, a property that was thought to reduce the autocatalytic effect of HCl evolved at the initial stages of dehydrochlorination. Since the induction time of the sample having 0.53% of zinc stearate and 0.53% of zeolite was higher than those of the PVC plastigels having only zinc stearate or zeolite, the synergistic effect on thermal stability was observed at low levels of these additives. J. VINYL. ADDIT. TECHNOL., 11:47–56, 2005. © 2005 Society of Plastics Engineers     

旋转模塑用聚氯乙烯增塑糊的研究

对影响ＰＶＣ增塑糊性能的五个因素：ＰＶＣ增塑糊的流变性能、糊粘度稳定性、脱气性能、凝胶化性能和塑化性能进行较为深入的研究；为确定ＰＶＣ增塑糊所用主要原料的种类和用量提供了有益的参考。     

辐照改性聚丙烯拉伸流变行为及其挤出发泡的研究

通过在线形聚丙烯中加入双官能团丙烯酸酯类单体,经小剂量γ射线高能辐照,制备了高熔体强度聚丙烯,研究了其拉伸流变行为及其在挤出发泡方面的应用。Rheotens拉伸流变测试表明,辐照改性后由于形成了长支化分子结构,聚丙烯的熔体强度、拉伸黏度显著提高,具有明显的应变硬化特征。实验表明,ZnO可明显降低AC发泡剂分解温度,缓和分解放热;在辐照改性制备的高熔体强度聚丙烯中加入AC／ZnO复合发泡剂,可挤出发泡得到泡孔尺寸较为均一、分布均匀、具有闭孔结构的发泡材料。     

聚乳酸/淀粉发泡片材的制备及性能

以甘油为增塑剂,偶氮二甲酰胺为发泡剂(AC发泡剂),采用模压法制备聚乳酸/淀粉发泡片材。通过对材料的力学性能,发泡密度、发泡倍率等测试研究了发泡剂含量、发泡温度、发泡时间及发泡压力对片材性能的影响。结果表明,发泡温度、发泡时间及发泡压力对片材的力学性能影响较大,AC发泡剂对材料发泡性能影响显著。当AC发泡剂用量为0.6份,发泡温度为200℃,发泡时间为4 min,压力为10 MPa时片材的拉伸强度达到27.91 MPa,断裂伸长率为3.65%,此时材料的发泡密度为1.08 g/cm3,发泡倍率为1.16,综合性能最佳。     

Meaningful evaluation of plastisol gelation and fusion temperatures by dynamic mechanical analysis

In most PVC plastisol processing operations, gelation and fusion characteristics of the plastisol are critically important. For example, in chemically foamed plastisols, plastisol fusion temperature and blowing agent decomposition temperature must be carefully coordinated. In rotomolded parts, rates of gelation may determine the quality of the finished parts. For plastisol products made by any process, the final fusion temperature determines the processing temperatures required to give the finished product acceptable mechanical properties. For a variety of reasons, the methods commonly used to characterize plastisol gelation and fusion (hot bar test, resin in plasticizer clear point, torque rheometer measurements, etc.) provide comparisons between plastisols but do not provide temperatures that are easily related to actual industrial processes. With dynamic mechanical analysis (DMA), one can characterize, under low shear conditions, the temperatures at which gelation begins, gelation ends, and complete fusion occurs. Additionally, it is possible to record plastisol viscosities (and other dynamic mechanical properties) over the processing temperature range. We used a multiple linear regression program to analyze the DMA data for plastisols heated from 30 to 210°C and containing either 70, 80 or 90 phr of Jayflex dihexyl phthalate (DHP) or Jaylflex di-isodecyl phthalate (DIDP). Further, we determined the plasticizer phr dependence and the reproducibility of gel and fusion temperatures given by data analyzed in this manner. Finally, for comparison, we analyzed the reproducibility of initial and final plastisol gel temperatures and fusion temperatures, which were determined by visually analyzing the DMA data for plastisols containing 70, 80, and 90 phr of Jyflex plasticizers DHP, Jayflex 77, diisononyl phthalate (DINP), and DIDP. Precise characterization of plastisol gelation and fusion behavior will, undoubtedly, facilitate substitution of plastisol ingredients as is often required by those who manufacture and process plastisols.     

Dielectric and electromechanical studies of plasticized poly(vinyl chloride) fabricated from plastisol

Poly(vinyl chloride) (PVC) plastisol is used in many industrial applications and is considered an electrically inactive material. To explore the potential of plastisol as an electroactive material, the dielectric properties, space charge distribution, mechanical properties, internal structure and electromechanical behavior of plasticized PVC (PVC gel) prepared from plastisol by heating were investigated. The gel exhibited a large dielectric constant at low frequencies (1–1000 Hz), an asymmetric charge distribution and excellent mechanical properties. Various DC electric fields were applied to the gel placed parallel between two electrodes and the electrostatic adhesive force to the anode was measured. The results of small‐ and wide‐angle X‐ray scattering suggested that the electromechanical properties of the gel originated from the characteristics of the physical crosslinking distance (ca 20 nm) of PVC in the gel structure. Considering the dielectric properties, space charge density and adhesion force to the anode, PVC gels prepared from plastisol using the heating method have potential for use as electroactive materials. © 2013 Society of Chemical Industry     

Solar spectral properties of PVC plastisol‐based films filled with various fillers

Plastisol is mostly a suspension of PVC particles in a liquid plasticizer that flows as a liquid and can be poured into a heated mold. For PVC plastisol applications, in addition to liquid dispersion performance and post‐dispersion flocculation resistance, outdoor durability is an important end use requirement. Spectral properties of PVC plastisol‐based films with or without additional near infrared (NIR) rays barrier fillers have been investigated. Both spherical and lamellar fillers have been incorporated in PVC plastisol at a weight content of 2% to 10% and results show a high impact on the reflectance in the NIR region and on the transmittance in the visible (Vis) region. Experimental results showed that the incorporation of nacre lamellar‐based filler in PVC plastisol did not permit favorably change its spectral properties while TiO₂‐based particles ensured a decrease of the transmittance in the Vis and an increase of the reflectance in the NIR. J. VINYL ADDIT. TECHNOL., 25:E188–E194, 2019. © 2018 Society of Plastics Engineers     

Viscoelastic measurements of PVC plastisol during gelation and fusion

This work is concerned with the change of viscoelastic properties of poly(vinyl chloride) (PVC) plastisol during heating. The system changes from a suspension of solid particles in a liquid medium to a swollen gel and further to a fused state as the temperature is raised. The Rheometrics mechanical spectrometer was used in the oscillatory mode at 0.1 Hz. The temperature of the sample was raised in a controlled manner to 195°C. During gelation, the viscosity increased rapidly about three decades. There was a similar increase of the elastic modulus. After reaching a maximum, both viscosity and elastic modulus decreased rapidly with the progress of fusion. The viscoelastic properties depended somewhat on the heating rate. At 170-195°C, it took a few minutes for the moduli to reach steady values. Continued heating, for several minutes at 195°C, did not change the moduli any further. The temperature range of the decomposition of a blowing agent in the plastisol foam formulation was determined. Over this temperature range, the viscoelastic properties change very rapidly. Quantitative estimates were made for the decrease of moduli during this period.     

Molded environment-friendly flame-retardant foaming material with high strength based on corn starch modified by crosslinking and grafting

A flame-retardant foaming material based on corn starch was prepared by a mold pressing method. The starch was crosslinked using Na₃[PO₃]₃ and became gelatinized. Initiated by (NH₄)₂S₂O₈, the starch was grafted with methyl acrylate and vinyl acetate by a free-radical polymerization. The starch was mixed with the foaming regent composed of NaHCO₃ and azodicarbonamide, and molded at 135 °C and 9 MPa for 10 min. A foaming material with a uniform honeycomb-like structure and relatively high strength was prepared. Its apparent density, tensile strength, impact strength and elongation were 0.685 g cm⁻³, 1.065 kJ m⁻², 3.025 MPa, and 28.8%. It held excellent flame resistance of V-0 rating. Na₃(PO₃)₃ acted both as crosslinker and flame retardant, which effectively simplified the formula. When the material was burnt, a compact charred crust was formed on its surface, which prevented the permeation of oxygen and the release of combustible organic compounds. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47193.