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.     

Processing conditions optimization for PVC plastisol rotational molding

In this work we present the optimization of the processing conditions for PVC plastisol rotational molding. The effects of oven temperature, processing time, rotational, speed and amount of plastisol over the degree of curing, physical appearance, and mechanical properties of the molded articles were studied. Also, using a simple mathematical model to simulate the temperature profiles of the plastisol inside of the spherical mold as a function of time, the viscosity change of the plastisol with time is reported. A rotational molding machine laboratory size was used for the experiments. The oven (at different points) as well as the mold (at the inside and outside of the cavity) temperatures were measured as a function of time in order to get a better understanding of the curing process. Such data in conjunction with the model gives the support for process optimization and control.     

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     

Selecting operating conditions for PVC plastisol fusion ovens

Gelation and ultimate fusion of layers of plastisol is a major step in producing finished spread-coated vinyl products. An analysis of the process has been made, concentrating on heat-up, required conditions for adequate fusion, and the associated plasticizer evaporation losses. It is further shown how the developed model can be used to help select optimal process conditions.     

Moisture absorption by PVC plastisol components

Moisture can be absorbed from the air by PVC plastisols and by the fused product. Water in plastisols can contribute to defects in films, sheet goods and foam products, usually in the form of depressions or craters. Water absorbed by thermoformable foam PVC sheets can result in defects in the molded product, often appearing as wrinkles. Correlation between the sum of the water absorbed by individual PVC plastisol components and the water absorbed by a fused thermoformable foam sheet suggests that moisture sensitivity of the product can be minimized by selecting plasticizers and PVC resins having low moisture absorption.     

Functional acrylic monomers as modifiers for PVC plastisol formulations

Functional acrylic monomers are used as coagents with polyvinyl chloride plastisols to improve abrasion resistance, tensile strength, chemical resistance, permanent set, hardness, and adhesion. The emphasis of this paper is on the enhancement of physical properties which can be achieved through addition of a variety of different functional acrylic monomers (mono-, di-, and tri-functional) to a PVC plastisol formulation. Collected test data will be given to show the effect these monomers have on the plastisol's physical properties.     

Rheology of plastisol formulations for coating applications

A plastisol is a suspension of PVC particles and mineral fillers in a liquid phase composed of plasticizer and adjuvants. Plastisol formulations are commonly used in coating processes for flooring application. In the knife‐over‐roll process, they are subjected to a wide range of shear rates (0–10⁵ s^?1). They are adjusted in order to fulfil the target end‐use properties but their processability depends on their rheology. Plastisol based on three PVC resins with or without mineral filler have been investigated using a Couette device and a capillary rheometer. Results show a high impact of PVC particle content, particle sizes and distribution on rheology: a polydisperse formulation displays a shear‐thinning behavior in the whole shear rates range and exhibits yield stress; a monodisperse formulation shows a shear thinning behavior at low shear rate, followed by a Newtonian plateau, then a more or less pronounced dilatancy peak depending on plasticizer rate and finally another shear‐thinning behavior; a bidisperse resin stands in between. Filler content also impacts the rheology: shear thickening effects at intermediate shear rates decrease or even disappear; however, the viscosity increase is important for low shear rates and depends on the filler particle size and particle size distribution. POLYM. ENG. SCI., 57:982–988, 2017. © 2016 Society of Plastics Engineers     

聚氯乙烯塑溶胶的"湿碰湿"技术

介绍了国外聚氯乙烯塑溶胶的“湿碰湿”技术,即在前一道涂层未经烘干的状态下直接进入下一道涂装工序,减少了烘烤的次数,并确保了各道涂装工序的质量与效果。     

耐热PVC增塑糊的研究

通常的PVC糊树脂热分解温度为160℃,从其流变特性出发筛选了各种热稳定剂及其他助剂,研究出比原来分解温度高出40~50℃PVC增塑糊制备方法,使其应用在热浸渍制品上,不仅保持原PVC增塑糊的一些性能,而且耐热性、透明性、附着力等都有新的改进,因而获得了良好的经济效益。     

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。     

浅谈聚氯乙烯塑溶胶在汽车工业中的应用

简要地介绍了汽车工业对聚氯乙烯塑溶胶的需求以及聚氯乙烯塑溶胶在汽车工业的应用.     

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%。     

Viscoelastic properties of branched polyacrylate melts

The viscoelastic properties of poly(n‐butyl acrylate), poly(ethyl acrylate) and poly(methyl acrylate) melts have been studied using samples that varied in both molar mass and the mol% branched repeat units, these properties having been previously determined by gel permeation chromatography and ¹³C NMR spectroscopy, respectively. Poly(n‐butyl acrylate) was studied most extensively using seven samples; one sample of poly(n‐butyl acrylate), two samples of poly(ethyl acrylate) and one sample of poly(methyl acrylate) were used to study the effect of side‐group size. Storage and loss moduli were measured over a range of frequency (1 × 10^?3 to 1 × 10² rad s^?1) at temperatures from T_g + 20 °C to T_g + 155 °C and then shifted to form master curves at T_g + 74 °C through use of standard superposition procedures. The plateau regions were not distinct due to the broad molar mass distributions of the polyacrylates. Hence, the upper and lower limits of shear storage modulus from the nominal ‘plateau’ region of the curves for the seven poly(n‐butyl acrylate) samples were used to calculate the chain molar mass between entanglements, M_e, which gave the range 13.0 kg mol^?1 < M_e < 65.0 kg mol^?1. The Graessley–Edwards dimensionless interaction density and dimensionless contour length concentration were calculated for poly(n‐butyl acrylate) using the mean value of plateau modulus (1.2 × 10⁵ Pa) and three different methods for estimation of the Kuhn length; the data fitted closely to the Graessley–Edwards universal plot. The Williams–Landel–Ferry C₁ and C₂ parameters were determined for each of the polyacrylates; the data for the poly(n‐butyl acrylate) samples indicate an overall reduction in C₁ and C₂ as the degree of branching increases. Although the values of C₁ and C₂ were different for poly(n‐butyl acrylate), poly(ethyl acrylate) and poly(methyl acrylate), there is no trend for variation with structure. Thus the viscoelastic properties of the polyacrylate melts are similar to those for other polymer melts and, for the samples investigated, the effect of molar mass appears to dominate the effect of branching. © 2001 Society of Chemical Industry     

Viscoelastic and acoustic characterization of polyurethane-based acoustic absorber panels for underwater applications

Acoustic absorbers that can have applications in a desired frequency band are a challenge often encountered in underwater acoustic absorber panel design. Polyurethane-based sound absorbing composite panels were designed with the help of finite element method (FEM) modeling using COMSOL for material formulations that can give optimum performance of echo reduction (ER) with minimum thickness. Polyurethanes of different compositions were evaluated for their acoustic performance using FEM modeling and experimental validation of the modeling results was done. The frequency-dependent modulus and damping properties were generated using dynamic mechanical analyzer and time–temperature superposition were performed to generate the material properties in the high frequency range (up to 25 kHz), which are significant for underwater acoustic detection applications and these data were used as inputs for modeling studies. Acoustic properties of the samples were experimentally evaluated using a water-filled pulse tube in 2–15 kHz frequency range as well as in an acoustic tank test facility for bigger dimension panels. These are nonresonant type absorbers capable to overcome limitations arising from environmental factors such as high hydrostatic pressures and also they are effective over a broad range of frequency (500 Hz–15 kHz) with ER > 15 dB. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47165.     

Pigments for PVC applications

Skillful selection and evaluation of pigments for use in PVC compositions demands careful recognition and interpretation of side effects. These include possible interfering effects due to additives such as lubricants, heat and light stabilizers, U.V. screeners, etc. In addition, it has been observed that pigments can chemically react with polymers (PVC included) initiating degradative processes or catalyzing oxidation of PVC or its additives. Other changes affecting pigment performance in PVC include its solvation by the polymer at high processing temperatures and particle size reduction by abrasion during high intensive premixing. Also, in applications where amount of heat build-up of dark vinyls due to light absorption is important, inorganic pigments are shown to be superior to their organic counterparts. However, care in controlling processing temperatures to preclude polymer-pigment reactions needs to be exercised when inorganic pigments such as iron oxide, cadmium yellow pigments, and any other mixed metal oxides are evaluated, for use in PVC compounds.     

NBR/PVC泡沫弹性体的研制

以NBR/PVC并用胶为主要原料 ,在化学发泡剂的作用下进行自由发泡制备密度低于 0 15Mg·m- 3的闭孔泡沫弹性体。利用正交设计得到试验条件下的最佳配方为 :NBR/PVC　 70 /30 ,硫黄　 0 8,促进剂EZ　 1 5 ,促进剂D　 0 5 ,发泡剂AC　 12 ,填料、增塑剂　适量 ;最佳发泡工艺条件为 :混炼胶在 110～ 130℃下预处理 10～ 30min ,在160℃左右自由发泡。     

Inert-gas extrusion of rigid PVC foam

A novel approach to the extrusion of high-density, rigid PVC foam uses commercial RPVC compounds with inert-gas physical blowing agents (carbon dioxide and argon). The process was developed on a segmented single-screw extruder with L/D of 40. On-line monitoring of process variables was also carried out. This technique provides an alternative to conventional processing methods using chemical blowing agents.