Showing papers in "Journal of Vinyl & Additive Technology in 1983"
TL;DR: In this article, a free radical mechanism started by absorption of energy sufficient to break chemical bonds is described, and some of the techniques for controlling the degradation of polyvinyl chloride weathering are described.
Abstract: Polyvinyl chloride weathering is a free radical mechanism started by absorption of energy sufficient to break chemical bonds. Absorption chromophores are often related to PVC heat history. Chemical bond energies are examined to indicate weak sites susceptible to initial degradation. Mechanisms of yellowing, oxidation, bleaching, and surface erosion are described. Some of the techniques for controlling the degradation of PVC are described. These techniques allow the PVC degradation to be controlled sufficiently so that PVC is accepted commercially as an excellent outdoor weathering material.
34 citations
TL;DR: In this paper, a laboratory test method for predicting maximum heat buildup due to the sun is described, and the effects of the sample thickness and gloss, carbon black and titanium dioxide levels, and distance of an infrared heat source from the sample on the heat buildup are also presented.
Abstract: PVC building products such as siding, windows, and roofings are exposed to the sun. Absorption of the sun's energy leads to a temperature rise, which may cause dimensional control problems, such as expansion and, in severe cases, distortion of the PVC products. The amount of heat buildup in the product depends on the color and/or pigment system of the PVC compound. Generally, the darker the color, the more the sun's energy is absorbed and the higher the temperature heat buildup. Because of the growing demand for darker colors of PVC building products, a test for measuring temperature rise to predict performance of the product in actual use is needed. A laboratory test method for predicting maximum heat buildup due to the sun is described in this paper. The effects of the sample thickness and gloss, carbon black and titanium dioxide levels, and the distance of an infrared heat source from the sample on the heat buildup are also presented in the paper.
18 citations
TL;DR: In this paper, a method has been proposed to estimate the rheograms of a PVC formulation at temperatures relevant to its processing conditions with the use of a master curve, knowing the melt flow index and glass-transition temperature of the formulation.
Abstract: A knowledge of the complete flow curve, or rheogram, of a PVC formulation depicting the variation of the melt viscosity over industrially relevant ranges of shear rate and temperature is essential in the design of polyer-processing equipment, process optimization, and troubleshooting. These data are generated on sophisticated rheometers that are beyond the financial and technical means of most PVC processors. The only flow parameter that can be readily measured on an inexpensive apparatus is the melt flow index of the resin-mix. In the present work, a method has been proposed to estimate the rheograms of a PVC formulation at temperatures relevant to its processing conditions with the use of a master curve, knowing the melt flow index and glass-transition temperature of the formulation. A master curve that coalesces rheograms of different PVC formulations at various temperatures has been generated and proposed as a tool for estimating the flow curve.
12 citations
TL;DR: In this paper, the effect of calcium carbonate particle size, coating, and usage level on the properties of PVC pipe has been investigated and the effects of varying the paraffin wax level and melt temperature have been explored.
Abstract: PVC pipe compounds typically contain varying amounts and types of calcium carbonates, paraffin waxes, and other ingredients such as stabilizers, titanium dioxide, calcium stearate, and processing aids. The purpose of this paper is to study the effect of calcium carbonate particle size, coating, and usage level on the properties of PVC pipe. In addition, the effects of varying the paraffin wax level and melt temperature will be explored. The paper describes these effects as a function of both impact strength and stress-rupture regression. Based on these results, a series of recommendations on type and usage level of the calcium carbonates and paraffin waxes, and processing conditions for the compound will be developed for use in guiding the pipe manufacturer towards producing PVC pipe that is both performance-oriented and cost-effective.
11 citations
TL;DR: The all-acrylic weatherable impact modifier is designed especially to modify rigid poly (vinyl chloride) compounds for outdoor use and ease of processability as discussed by the authors, and its key performance features with special emphasis on the processing advantages of the allacrylic impact modifier.
Abstract: Rigid poly (vinyl chloride), PVC, is finding increasing use in outdoor applications as a replacement for conventional materials such as wood, aluminum, steel, and other materials. Formulating PVC for outdoor applications requires special attention to several essential properties in order to achieve the high-quality standards needed over a long period of time. One area that needs modification in a rigid PVC formulation for outdoor applications is toughness. Impact modifiers used to improve the toughness of PVC in outdoor use are CPE, EVA copolymers, and acrylates.
The all-acrylic weatherable impact modifier is designed especially to modify PVC for outdoor use and ease of processability. We will review its key performance features with special emphasis on the processing advantages of the all-acrylic impact modifier. The study of the influence of processing conditions on the physical performance of weatherable PVC compounds in a Ba/Cd stabilized window profile shows an acrylic modifier to give consistently high toughness over a wide temperature range and shearing friction.
11 citations
TL;DR: In the early 1960s, vinyl house siding was first commercialized as discussed by the authors, and powder compounds were first introduced in the late 1960s and twin-screw extrusion was used to produce a well-fused and tougher product.
Abstract: In the early 1960s, vinyl house siding was first commercialized. The colors were pastels and included white, green, yellow, and gray. All siding tended to bleach and fade (oxidize) to an extent where medium and dark colors were unacceptable, since the fading is more noticeable in deeper colors. All the early siding was made from cubes on single-screw extruders. Powder compounds were first introduced in the late 1960s, as was twin-screw extrusion. At the same time higher processing temperatures were used on, both twin- and single-screw extruders. That led to a well-fused and tougher product. Formulation changes reduced bleaching and fading and permitted such medium-depth colors as tan, gold, beige, blue, and olive.
This technology allowed rapid growth in the vinyl siding industry in the late 1970s. Surface distortion (oil canning) was recognized as a potential problem with the early gray color and recognized as a major problem with dark colors; it was resolved only by understanding the fundamental principles involved. Another major problem was the fading in dark colors and here again extensive research into the principles of weathering led to the use of a thin, highly weatherable capping as a cost-effective solution.
For the future, many technical developments can be expected in this rapidly growing market. However, judging by the occasional withdrawal of a formulation from the market, and by an occasional homeowner complaint, present performance in several properties must be judged as just adequate. For this market to continue its rapid growth, future performance should be better than today's. This can be accomplished without hurting economics by careful understanding of all parameters involved. Formulation changes will allow better performance. Standards must be raised to control product performance, especially surface distortion and color stability in darker colors, and to insure retention of physical properties after long-term weathering.
8 citations
TL;DR: In this article, five to 15 percent of ethylene/vinyl acetate copolymers were compounded into rigid polyvinyl chloride, with the copolymer dispersed as discrete micro-domains, produced very efficient synergistic improvement of impact strength.
Abstract: Five to 15 percent of ethylene/vinyl acetate copolymers was compounded into rigid polyvinyl chloride, with the copolymers dispersed as discrete micro-domains, produced very efficient synergistic improvement of impact strength; as the vinyl acetate content of the copolymer increased from 28 to 60 percent, the synergistic peak moved to higher copolymer content and became higher and broader. Copolymer content correlated directly with melt flow and thermal stability, and inversely to modulus, strength, and heat-deflection temperature. The vinyl acetate content of the copolymer correlated directly with elongation, impact strength, and thermal stability, but inversely to modulus, heat-deflection temperature, low-temperature flexibility, and melt flow. When the copolymer content reached 25 percent, it formed a second continuous-phase, interpenetrating the polymer network structure and acting as a polymeric plasticizer, producing thermoplastic elastoplastics.
7 citations
TL;DR: In this article, the measurement of primary particle breakdown through microscopic observation, torque bowl rheometry, penetration impact, yield stress determinations, and zero-length capillary Rheometry is presented.
Abstract: The breakdown of primary particle structure in PVC is intimately related to the mechanical properties of the material. This article addresses the measurement of primary particle breakdown through microscopic observation, torque bowl rheometry, penetration impact, yield stress determinations, and zero length capillary rheometry. It is found that each method gives information which identifies certain stages in the breakdown process and complements information obtained from the other methods. Characterization via penetration impact identifies the melt conditions at which both the onset of a continuous network on the microscopic scale and primary particle breakdown occurs. Yield stress determined as a function of melt temperature identifies the completion of primary particle breakdown. The onset of primary particle breakdown, as well as the breakdown of other structural units, such as grains, are readily determined by torque bowl rheometry. However, the results from zero-length capillary rheometry cannot, as yet, be readily generalized in terms of the particulate breakdown process.
6 citations
TL;DR: In this paper, the authors determine whether or not chloroform (CHCl3) and carbon tetrachloride (CCl4) diffuse from poly(vinyl chloride) (PVC) or chlorinated polyvinyl chlor chloride (CPVC) pipe into water in the absence of solvent cement.
Abstract: The objective ofthis study was to determine whether or not chloroform (CHCl3) and carbon tetrachloride (CCl4) diffuse from poly(vinyl chloride) (PVC) or chlorinated poly(vinyl chloride) (CPVC) pipe into water in the absence of solvent cement. Milli Q water (water which has been deionized, demineralized, and purified of residual organic matter) and tap water were permitted to stand in specimens of recently extruded pipe for 14 days in an attempt to simulate a condition of prolonged stagnation. The CHCl3 and CCl4 in the water were then measured utilizing an analytical method sensitive to 0.01 μg/1 (ppb).
CHCl3 and CCl4 do not diffuse from Geon PVC or TempRite CPVC pipe or fitting compounds in significant quantities under these test conditions. Where sporadic positive responses were noted, these were in the low or fractional μg/1 (ppb) ranges and are far lower than levels commonly found in chlorinated tap water. The low, sporadic values obtained for CHCl3 and CCl4 in both Milli Q and tap water do not permit the calculation of meaningful diffusion constants.
5 citations
TL;DR: In this article, the authors summarize the current technical knowledge of real fire behavior, and use this understanding to interpret available data for PVC in large and small-scale fire tests, and bring a sense of technical realism to the issues involved.
Abstract: The role of PVC in fires is currently a controversial topic because of the many negative comments made about PVC on the occurrence of any major fire disaster. Critics also use many small-scale smoke and toxic gas tests to define the role of PVC in these fires. The purposes of this paper are (1) to summarize the current technical knowledge of real fire behavior, (2) use this understanding to interpret available data for PVC in large- and small-scale fire tests, and (3) help bring a sense of technical realism to the issues involved.
5 citations
TL;DR: In this paper, standard PVC compounds containing various lubricant systems were fused in a Haake Torque Rheometer equipped with a torque integrator, holding the shear stress time value constant.
Abstract: Standard PVC compounds containing various lubricant systems were fused in a Haake Torque Rheometer equipped with a torque integrator, holding the shear stress time value constant. The total work put into the system to fuse the compound was therefore held constant. The fused material was compression molded into sheeting for physical testing. The data will characterize the compounds for both rheological and physical properties at several processing conditions. Plotted curves will depict the lubricant systems and processing temperatures necessary to obtain maximum physical strength.
TL;DR: In this article, a zero-length capillary was used to measure the entrance pressure loss for suspension PVC rigid dry blend at various stages of fusion, and the initial decrease in the admission pressure curve during processing was related to the fusion of the primary particle agglomerates.
Abstract: The mechanism of fusion of suspension PVC rigid dry blend in low-shear processing involves the compaction, densification, intergrain fusion, and elongation of the grains. Using a “zero-length” capillary, the entrance pressure loss was measured for dry blend at various stages of fusion. The initial decrease in the entrance pressure loss curve during processing is related to the fusion of the primary particle agglomerates. The consequences of the entrance pressure loss decrease on the rate of melting during extrusion are discussed.
ARCO1
TL;DR: In this article, a styrene maleic anhydride copolymers blended with polyvinyl chloride (PVC) is used to produce alloys that exhibit elevated thermal properties and improved processability.
Abstract: Styrene maleic anhydride copolymers blended with PVC result in alloys that exhibit elevated thermal properties and improved processability. These improvements will help PVC usage in electrical/electronic housings. The PVC component maintains flame retardance for the compound, without the need for further additives.
TL;DR: In this paper, the authors consider the potential of polyvinyl chloride for the manufacture of flexible products, by introduction of plasticizers, generally characterized by a good solubility in the polymer and low volatility.
Abstract: Poly(vinyl chloride) could be considered as an ideal basis for chemical modifications, due to its chemical structure, which contains the repeating unitCH2CHCl. Presumably, the chlorine may react as in other chlorine-containing aliphatic compounds, but secondary degradation reactions will occur at the same time, due to irregularities in the polymer structure and consequential lowering of the intrinsic reactivity site. Nevertheless, various functional modification reactions (grafting and crosslinking), were carried out in solution and in the condensed state, in order to improve specific properties of the polymer, leading to a larger scale of applications. Furthermore, it is also important to note the potential of PVC for the manufacture of flexible products, by introduction of plasticizers, generally characterized by a good solubility in the polymer and low volatility. In order to improve the aging properties of these products, recent developments were made in the field of oligomeric and polymeric plasticizers, which may or may not be reactive. The success of this new direction depends on larger developments in reactive processing.
TL;DR: In this paper, the suitability of CaCO3 fillers in exterior PVC applications was evaluated and it was found that the surface-treated precipitated caCO3s of average particle sizes 0.5 micron and 0.07 micron, in fact, minimized the initial yellowing of PVC seen on weathering.
Abstract: A study conducted to determine the suitability of calcium carbonate (CaCO3) fillers in exterior PVC applications revealed that the surface-treated precipitated CaCO3s of average particle sizes 0.5 micron and 0.07 micron, in fact, minimized the initial yellowing of PVC seen on weathering. It is hypothesized that these particle-size CaCO3s, being optimum for light scattering, provide greater UV protection. Further, the high surface areas of these CaCO3s increase the capacity to neutralize the HCl responsible for yellowing of the PVC. The optimum filler level is 5 to 10 phr. At this loading level, long-term impact strength is also retained.
TL;DR: In this paper, a method of determining the midplane temperatures of vinyl extrusions is presented. But the method is limited to the case of a single extruder and is not suitable for other extruded parts.
Abstract: This paper deals with a method of determining the midplane temperatures of vinyl extrusions. Knowing the surface temperature, cooling medium temperature, and flow rates, the theoretical midplane temperature can be calculated. Determining and controlling midplane temperatures of vinyl extrudates is essential for consistent part fabrication. Data are presented illustrating how flow rate of the cooling medium affects surface and midplane temperatures of the vinyl extrudate. Enthalpy and flow rate data are used to determine cooling bath requirements.
TL;DR: In this article, a comparison of some of the more commonly used air release tests of the PVC plastisol industry, i.e., Huff ring test, air injection by syringe, and air entrapment by stirring, is presented.
Abstract: The formation of stable air bubbles during processing is one of the most critical problems encountered in many PVC plastisol applications (often referred to as the “air release problem”). Stable bubbles can lead to both cosmetic and structural defects in finished products. Analysis of the air release problem has been difficult not only because air release is affected by many variables (some of which are interrelated), but also because no air release test has been universally accepted as being reliable. This paper presents a comparison of some of the more commonly used air release tests of the PVC plastisol industry, i.e., the Huff ring test, air injection by syringe, and air entrapment by stirring. Our investigation indicates that results obtained from these air release tests strongly depend upon test procedure, test environment, plastisol age, and even the amount of plastisol in the test container. Among the test methods which were examined, air entrapment by stirring was found to be the most convenient and reliable. Possible causes for the observed discrepancies among the tests and data scatter within each test are discussed in terms of variables which affect bubble stability, such as bubble size, rheology, film stress distribution, surface tension, and the Marangoni effect.
TL;DR: In this article, the suitability of both organic and inorganic pigments for rigid vinyl windows is discussed, and the contribution of other additives to appearance retention of colored rigid PVC is discussed.
Abstract: Europe has experienced phenomenal growth in the market share of rigid vinyl windows. The American market has shown intensified interest in dark brown rigid vinyl windows. European experience with these pigmentation systems provides a useful data base for designing these dark brown shades suitable for use in North American climatic conditions. Criteria for pigment selection are discussed, including the suitability of both organic and inorganic pigments. Test data are provided for selected pigment systems to show their suitability with regard to several application parameters. The contribution of other additives to appearance retention of colored rigid PVC is discussed. Typical formulations are presented in detail.
TL;DR: The use of poly(Vinyl chloride) is the basic material for a huge number of products which are fabricated using very many different techniques, such as molecular orientation, foaming, and cross-linking.
Abstract: Poly(Vinyl chloride) is the basic material for a huge number of products which are fabricated using very many different techniques. Established processing techniques continue to be improved, leading to additional benefits in process efficiency and product quality. New processes are also being introduced which are intended to increase the efficiency of material usage and to open up new application areas. These include: molecular orientation, foaming, and cross-linking. Developments are also occurring in the use of PVC in conjunction with other materials as micro- or macro-composites. Processing techniques include coextrusion and lamination. Many processing methods are likely to benefit from the microelectronics revolution in process control and monitoring.
TL;DR: Pigments selected from the iron oxide, chromium oxide and furnace black families, which offer the possibility of preferred earthtone colors, were characterized for: their stability at PVC processing temperatures; their effect on longterm ultraviolet exposure, and their infrared absorption properties that relate to heat buildup and buckling in the composite as discussed by the authors.
Abstract: Pigments selected from the iron oxide, chromium oxide and furnace black families, which offer the possibility of preferred earthtone colors, were characterized for: their stability at PVC processing temperatures; their effect on long-term ultraviolet exposure, and their infrared absorption properties that relate to heat buildup and buckling in the composite. This study has basically ranked the pigments into three categories in terms of their overall performance. Besides the earthtone color, the added economics of these pigments makes them of prime interest for external applications.
TL;DR: The correction for polymer and mercury compressibility is essential to the use of mercury porosimetry for the evaluation of the porosity of poly(vinyl chloride) (PVC) suspension granules as mentioned in this paper.
Abstract: The correction for polymer and mercury compressibility is essential to the use of mercury porosimetry for the evaluation of the porosity of poly(vinyl chloride) (PVC) suspension granules. The polymer compressibility, however, varies with the morphology type of the granules. The technique outlined in this paper allows the appropriate correction to be made without the need for the prior determination of the polymer compressibility. Bulk-compressibility factors for the polymer samples are derived from the porosimetry data.
Surface areas of PVC granules, as derived from porosimetry data using two fundamentally different techniques, are in error because of the presence of “ink-bottle” shaped pores.
TL;DR: In this article, the authors present the reasons of the economic recession prevaling in the European plastics industry for a number of years, notwithstanding the temporary upsurge of 1979, in a review of aspects relative to internal economic government policies in Europe, relative to external trade and relative to the Community's policies towards Third World countries.
Abstract: Following a decade of strong development of plastics consumption, the European market and the production of European manufacturers have fallen back into stagnation since the oil crisis of 1973, followed by the second oil-price explosior. of 1979. The author presents the reasons of the economic recession prevaling in the European plastics industry for a number of years, notwithstanding the temporary upsurge of 1979, in a review of aspects relative to internal economic government policies in Europe, relative to external trade and relative to the Community's policies towards Third World countries. Prospects for the European plastics industry are considered as a function of economic and industrial government policies in Europe, of development in third countries, and of new approaches by the European industry. The various aspects considered are illustrated in particular by the case of PVC, a typical representative of the major plastics reviewed.