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.     

A comparative study of branched and linear dialkyl phthalate plasticizer surface levels and their effects on adhesive bonds in flexible PVC

A method has been developed to quantitatively measure the surface plasticizer levels present on test plaques made from a plasticized PVC compound. The plaque fabrication conditions have been chosen so that the plaque closely models an extruded flexible PVC profile. The analysis method utilized sorption of the surface plasticizer on fumed silica, followed by methanol extraction and liquid chromatographic identification and quantitation of the plasticizer. Typical results are presented for a model compound plasticized with either di-2-ethylhexyl phthalate (DOP) or a mixture containing predominantly linear C₇, C₉, and C₁₁ dialkyl phthalates (DHNUP). The effect of compound work level, as measured by Banbury drop temperature and final processing temperature, has also been studied. These results show that, for the model compound studied, the average surface level of DHNUP is always greater than that of DOP. The DOP levels are essentially independent of compound work level. The DHNUP levels generally increase with increasing mold temperatures. Finally, this data has been correlated with a study of the lifetime of a Neoprene-based adhesive bond to DOP-and DHNUP-plasticized flexible PVC in a 100°C oven. These studies clearly show that a one-to-one substitution of DOP for DHNUP will increase the time to adhesive bond failure by a factor of at least 10 with this particular adhesive system and model compound.     

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.     

Measurement of PVC fusion (gelation)

PVC fusion (gelation) occurs with melting of crystallites followed by recrystallization. This recrystallization, as it occurs at the primary particle boundary, physically ties together the structure into a three dimensional network. One way of measuring the extent of this three dimensional network structure is to measure the force required to deform the material through a zero land length capillary. We examine this test method for various molecular weight PVC compounds, with and without plasticizer, and for various degrees of grinding the product.     

Soft PVC foams: Study of the gelation,fusion and foaming processes. III. Mixed phthalate ester plasticizers

The foaming of PVC (poly(vinyl chloride)) plastisols is a complex combination of simultaneous processes, involving the curing and structural changes of the plastisol, the gas generation and the foam formation. Our comprehensive study of such processes and of the influence of plasticizer on the foam quality has shown that all the processes involved have to be adequately synchronized to obtain foams of the required quality. A series of plastisols prepared by mixing a high and a low compatible phthalate ester plasticizer in several proportions (100/0, 75/25, 50/50, 25/75, 0/100 ratios) has been studied and characterized (by means of rheology, calorimetry, thermal stability, thermomechanical properties, density, and foam morphology), to study the influence of the plasticizer in such processes with changing compatibility. We found expectable rheological and calorimetric behavior regarding the plastisols without curing; however we experienced nonlinear (unexpected) behaviors in cases of foams and plastisols being cured. To confirm such behavior and our hypothesis regarding the possible plasticizer evaporation, the thermal stability of the plastisols, precured samples and foams have been studied by themorgravimetric analysis (TGA). According to our results it can be deduced that the plasticizer loss occurring in some cases during the production of the foams or the specimens being characterized, plays an important role in the foaming process and also influences the foam quality. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

低温塑化型PVC塑溶胶用封端聚氨酯的研制

以异佛尔酮二异氰酸酯(IPDI)、聚己二酸丁二醇酯(PBA)和丙酮肟(DMKO)等为原料合成了封端聚氨酯(BPU),并以BPU作为附着力促进剂,加入到聚氯乙烯(PVC)增塑糊中,制备出一种低温塑化型车用PVC塑溶胶。研究了BPU对车用PVC塑溶胶的附着力、拉伸强度、断裂伸长率、剪切强度和耐过烘烤性能的影响。结果表明:加入适量的BPU后,可以明显提高车用PVC塑溶胶在电泳漆板上的附着力,使塑溶胶的塑化温度降低至120℃左右;经170℃烘烤后,塑溶胶仍保持较好的附着力且不黄变,其拉伸强度、断裂伸长率和剪切强度分别提高了62%、41%和57%。     

甘油酯型聚氯乙烯增塑剂的研究

以甘油、苯甲酸和乙酸为原料合成了苯甲酸乙酸甘油酯,采用FTIR和力学性能测试研究了合成产物的结构及其对聚氯乙烯的增塑性能.结果表明,合成的苯甲酸乙酸甘油酯对PVC具有优良的增塑性能.     

Viscosity aging of poly(vinyl chloride) plastisol: The effect of the resin type and plasticizer type

The viscosity of freshly prepared poly(vinyl chloride) (PVC) plastisol increases with time, and this phenomenon is called viscosity aging. The increase is rapid in the beginning and slows down to a quasistable value, but a very slow increase continues. The phenomenon may be a result of either the deagglomeration of agglomerated particles or the dissolution of low‐molecular‐weight PVC into the plasticizer. In this work, two typical commercial resins were used, one containing friable agglomerates and the other containing nonfriable agglomerates. With the friable‐agglomerate resin, about 40% of the initially present agglomerates deagglomerated, whereas the viscosity increased in a week to twice the initial value. With the nonfriable‐agglomerate resin, very fine and very low molecular weight particles, about 3% of all the particles, dissolved into the plasticizer in 2 days. The effect of the plasticizer type on the viscosity aging through deagglomeration was investigated with four plasticizers and three plasticizer blends. The emulsifiers used for polymerization, and retained through drying, affected the aging in the beginning. On the other hand, the viscosity after 1 week was free from the effect of the emulsifier and was affected only by the plasticizer type. With the exception of two blends, the 1‐week viscosity was quantitatively related to the dielectric constant divided by the molecular weight of the plasticizer. For the plasticizer blends, one of the plasticizers could have a dominant effect on the promotion of deagglomeration. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 448–464, 2005     

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.     

提高PVC塑溶胶粘合力研究

ＰＶＣ塑溶胶配制的密封胶具有单组分、无溶剂、贮存稳定及弹性好、耐化学介质优良等特点、缺点是粘合力差。本文介绍了环氧树脂、聚氨酯树脂、聚酰胺树脂、丙烯酸树脂、尿素树脂等对ＰＶＣ塑溶胶的增粘作用,论述探讨了增粘剂的结构特点和增粘机理,以及油面胶的配制。     

Effect of plasticizer concentration and annealing on the structure of PVC

Samples of poly(vinylchloride) with various amounts of di-2-ethylhexyl phthalate plasticizer have been prepared by casting from solution. The enthalpy of fusion of these samples has been measured using differential scanning calorimetry. The results presented show the dependence of the enthalpy of fusion on plasticizer concentration, annealing time and annealing temperature to which the samples were subjected. The results indicated that the addition of plasticizer has surprisingly little effect on the crystallinity of commercial PVC. Small angle X-ray scattering measurements have also been carried out on samples of PVC plasticized with two different plasticizers. There was considerable similarity found between the two samples. Therefore SAXS results cannot be taken on the whole as a measure of crystallinity in this material.     

Migration of plasticizer di-2-ethylhexyl phthalate from PVC packaging material into cured meat

利用增塑剂DEHP的皂化反应,采用膜/肉接触的比色管模式和气相色谱法,研究了温度、时间、脂肪含量和加工方式等因素对PVC膜中的增塑剂DEHP向广式腊肠迁移的影响。结果表明：随着温度的升高,时间的延长,脂肪含量的增加,DEHP向肉中的迁移量均会增大;在紫外照射、微波辐射和高温蒸煮等条件下,DEHP的迁移量也会增加,其中微波辐射的作用较为明显,如微波照射18 s后,DEHP的迁移量高达189.3342 mg/kg,紫外光照射48 h后,迁移量是173.5921 mg/kg。同时研究了DEHP迁移溶出后,PVC膜的拉伸性能、断裂伸长率、透氧率和透湿率等性能的变化。结果表明：当增塑剂DEHP迁移溶出后,PVC膜的阻隔性和力学性能也发生了明显的变化,随着时间的延长、迁移量的增大,其PVC膜的拉伸强度逐渐升高,断裂伸长率逐渐降低,PVC膜的透氧率和透湿率也降低。     

固体酸催化合成邻苯二甲酸线性高碳醇酯

研究了不同固体酸催化邻苯二甲酸线性高碳醇酯的催化活性，及反应条件对酯化反应的影响，确定了较佳的反应条件。实验结果表明：以固体超强酸为催化剂，醇酐的物质的量比为2.25：1，催化剂的用量占总投料量的5％，带水剂环已烷占投料量的20％，酯化率超过97％。     

Effect of mechanochemical degradation on gelation and mechanical properties of PVC

The effect of vibromilling or jet milling on gelation and mechanical properties of poly(vinyl chloride) (PVC) was studied through SEM, FTIR, DSC, and mechanical properties tests. The experimental results show that the size of the grain and apparent density of PVC are decreased. The grains become much more loosely aggregated and the crystallinity of PVC is decreased during milling. The extensional fracture of degraded PVC is obviously different from that of undegraded PVC, the tensile strength and degree of gelation of degraded PVC are increased as compared with undegraded PVC. The mechanical properties of PVC are improved quite a lot after blending it with a small amount of mechanochemically degraded PVC. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 2273–2281, 1997     

邻苯二甲酸酯类增塑剂的危害及监管现状

概括性介绍了邻苯二甲酸酯引发的产品安全事件,汇总整理了目前关于邻苯二甲酸酯类增塑剂的危害性描述,分析研究了主要国家对相关产品中邻苯二甲酸酯类增塑剂的法律限制要求和检测方法标准,最后提出了关于产品中邻苯二甲酸酯类增塑剂的监管建议。     

Effect of plasticizer functionality on the performance properties of flexible PVC compounds

This paper is on the enhancement of physical properties achieved through utilization of linear plasticizers in flexible PVC compounds. This paper also emphasizes the use of statistical methods and designs of experiments. In a series of experimental designs, electrical, oven-aging, and low temperature performance of commercially available phthalate plasticizers were evaluated. Test data will be given to show the effect of plasticizer functionality on the performance properties of flexible PVC compounds.     

Soft PVC foams: Study of the gelation,fusion, and foaming processes. I. Phthalate ester plasticizers

The use of foamed plastics gains more and more interest every day. Flexible poly(vinyl chloride) (PVC) foams have excellent mechanical properties and low price, thus their application is extensive. Foams are produced from plastisols, which are based on the suspension of the PVC resin in a plasticizer. Phthalates are the most used plasticizers in flexible PVC foam formation. In this study, we have studied the influence of the phthalate ester‐type plasticizers on the foaming process and the quality of the foams obtained from the corresponding plastisols. For the plastisols prepared with the nine phthalate plasticizers considered, we have studied and discussed the complex and extensional viscosities; the thermal behavior (DSC) including the decomposition of the chemical blowing agent, and the foam production by rotational molding. In addition, we have characterized the foams obtained by thermomechanical analysis, density, and bubble size distribution. As expected, clear correlations have been obtained between the molecular weight and structure of the plasticizer with the rheological behavior of the plastisols. The knowledge of the gelation and fusion processes and evolution of the extensional viscosity of the plastisols combined with the study of the thermal decomposition of the blowing agent in each plastisol allows for better understanding of the complex dynamic behavior of these foaming systems. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Mechanical and morphological characterization of PVC plastisol composites with almond husk fillers

The present study develops new composite materials derived from environmentally friendly material, based on lignocellulosic fillers combined with a thermoplastic matrix. Almond husk, obtained as a by‐product of the agri‐food industry, has been used as a filler, combined with PVC thermoplastic matrix. This composite type (lignocellulosic material/thermoplastic matrix) is the object of this work for the advantages that it offers in environmental protection terms. With a view to identifying the degree of influence of filler amount, plasticizer concentration, and filler particle size on the properties of this new composite, we tested its mechanical properties and analyzed tensile fracture surfaces using scanning electron microscopy. POLYM. COMPOS., 28:71–77, 2007. © 2007 Society of Plastics Engineers