Weatherability of rigid vinyl siding

Vinyl siding is described as a product in the early maturity stage of business development. The competitive position of rigid vinyl siding vis-a-vis other products is discussed. Total weathering exposures from point sources not usually thought of are reviewed. Methods of control for weathering caused changes as well as resistance evaluation are covered. The impact on the industry of the voluntary product standard PS55-72 is mentioned.     

Compound requirements for vinyl siding

Basic principles of good compounding for weatherable vinyl siding are discussed. Appropriate level of stabilizer is such that 50 percent of initial should remain after the extrusion process. Balanced lubrication is necessary. Judicious choice of pigments and impact modifiers is called for. The cited references give added substance to this review paper.     

Attack of the artillery fungus on vinyl siding

The artillery fungus, Sphaerobolus stellatus, ejects dark‐colored spores for a distance of several meters. These are enclosed in an adhesive layer comprised of carotenoid pigments. On exposure to sunlight, the pigment layer resinifies and develops a strong bond to vinyl siding capstock. The damage is compounded when the homeowner removes the bonded spores abrasively, destroying the protective capstock layer. Strategies to protect vinyl siding or to defeat the microorganism are discussed. J. VINYL. ADDIT. TECHNOL., 11:63–64, 2005. © 2005 Society of Plastics Engineers     

A novel impact modifier system for vinyl siding and profile substrate

The use of a newly developed ABS impact modifier in coextruded vinyl siding and window profile substrate is discussed. Considerations of toughness at room and low temperature, output, reduced lubricant levels, and weatherability of the finished siding are reviewed. Actual outdoor weathering results are presented, along with long-term heat aging tests, showing the modifier to have good property retention characteristics.     

Formulations for vinyl house siding: History,present, future

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.     

Precipitated calcium carbonates as weathering enhancers and impact modifiers for rigid PVC siding and profiles

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.     

Fourier transform infrared micro spectroscopy mapping. Applications to the vinyl siding industry

Fourier transform infrared (FT-IR) micro spectroscopy is a powerful analytical technique capable of yielding high quality information with a spatial resolution as low as 10 microns. When coupled with an automated mapping stage it can offer unique evaluation capabilities. This paper describes a number of applications of FT-IR micro spectroscopy mapping to the vinyl siding industry. Examples will focus on determining, in single sample mapping experiments, the compositional changes associated with capstock to substrate transition and evaluating the degradation species and level observed during weathering exposure throughout the thickness of the siding panel.     

World-wide weathering of poly(vinyl chloride)

In order to determine the effect of outdoor aging in various areas of the world, poly(vinyl chloride), PVC, compositions were exposed at test sites in Australia, Canada, England, Germany, South Africa, and in Piscataway, New Jersey. These results are related to the climatological data from the different test sites. The data obtained show the effects of a three-year period of exposure on clear and filled, flexible and rigid PVC compositions. The merits of various types of additives are shown in respect to the outdoor aging properties of PVC compounds. It was observed that the exposure conditions vary from severe for Australia and South Africa to mild for England. However, the general results obtained throughout the world correlate well with those from the exposure site in New Jersey.     

Superior balance of weatherability and impact performance with acrylic‐capped vinyl siding

Vinyl siding, particularly in darker colors, has to be durable and be able to retain most of its original color when exposed outdoors. As the color palette for vinyl siding has been expanding and more and more colors are being offered to the homeowner, the need exists to improve color hold. A new acrylic capstock polymer, based on core‐shell technology, which can be coextruded onto vinyl siding, has been shown to provide excellent color retention, with good processability, impact and impact retention, and suitable gloss. The properties of this new capstock polymer are compared to other choices for capping vinyl siding. J. VINYL ADDIT. TECHNOL., 13:26–30, 2007. © 2007 Society of Plastics Engineers.     

The appearance retention properties of poly (vinyl chloride) compounds during weathering

Damage to poly (vinyl chloride) (PVC) compounds due to thermal degradation during processing has an important influence on its subsequent weatherability. High melt temperatures and/or high residence times cause white PVC to become more yellow and colored PVC to fade and bleach more upon weathering. If high melt temperatures are used, then short residence times are needed to maintain excellent weatherability. In addition to careful consideration of extrusion conditions, stream-lined equipment is necessary to produce extrudate of uniform thermal history. Also, relatively high thermal stabilizer levels help reduce thermal damage and, therefore, improve weatherability. Impact resistance is better retained when processing occurs at higher melt temperatures. A reasonable compromise between extrusion rate and temperature must be reached to provide for adequate color and impact retention.     

Prediction of the long-term outdoor weathering of poly(vinyl chloride)

The prediction of the long-term durability of PVC polymeric material has been a controversial subject for a long time. Attempts to evaluate this durability have indeed largely preceded experiments on the basic mechanisms of PVC degradation, and they have been essentially empirical. The present paper reports on the general rules that have to be followed to avoid basic errors in predicting the performance of PVC compounds from accelerated weathering experiments.     

Effects of process temperature on the weathering performance of rigid poly(vinyl chloride)

Elevated process temperatures can accompany current high extrusion rates of rigid poly(vinyl chloride). Various colored weatherable siding compounds were studied in the processing temperature range of 193°C to 227°C. The extruded compounds showed only minor color shifts due to increased melt temperatures. Outdoor exposure through four years in Arizona, Florida, and Ohio demonstrated typical color change but did not exhibit significant color shift relating to the initial processing temperatures. The samples extruded at elevated melt temperatures did demonstrate reduced impact strengths prior to outdoor exposure. Florida‐exposed and Ohio‐exposed samples lost impact strength throughout five years of exposure, with the samples processed at higher temperatures continuing to show lower impacts over time.     

The weathering of engineering thermoplastics

The photostability of four engineering thermoplastics, ARDEL, CYCOLOY, NORYL, and HOVEL, have been examined by mandrel bend tests on extruded channel as well as infrared and ultraviolet-visible spectroscopy on thin films. ARDEL D-100 and ROVEL 501 resins were found to have excellent stability to simulated sunlight, while CYCOLOY HHI and NORYL PX 1278 were found to have poor light stability. ARDEL is a polyarylate composed of bisphenol A. terephthalic acid, and isophthalic acid condensation units. CYCOLOY is an alloy of acrylonitrile-butadiene-styrene and polycarbonate. NORYL is a blend of poly(phenylene oxide) and polystyrene. ROVEL is an olefin-modified styrene-acrylonitrile.     

Accelerated weathering of pectin/poly(vinyl alcohol) blends studied by spectroscopic methods

The blends of pectin (PEC) and poly(vinyl alcohol) (PVA) at different components ratios were prepared by mixing in water. Thin polymeric films of PEC/PVA blends and pure polymers were obtained by casting method. All samples were then artificially aged using Suntest apparatus (Atlas) up to 780 h. The changes in chemical structure during sample ageing have been monitored by infrared and ultraviolet‐visible absorption spectroscopies. The first stage of weathering (up to ～ 300 h) was very slow and alteration of chemical structure was negligible in all samples. Prolonged ageing (>300 h) caused more significant degradation processes. FTIR spectra exhibited the highest changes in hydroxyl and carbonyl band ranges indicating the efficient photooxidation of macromolecules. The mechanisms of the observed processes have been discussed. It was found that PVA undergoes faster photoxidative degradation than pectin aged at the same conditions. The PEC/PVA blends exhibited the improved resistance to weathering comparing with both polymers aged individually. Mutual stabilization effect can be explained by intermolecular interactions between PEC and PVA confirmed by spectroscopic methods. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The weathering degradation of polyolefins

The mechanism of weathering degradation of polyolefins is discussed. Variations in spectral radiation, temperature, density, polymer absorption spectra, orientation, and sample thickness are related to property deterioration. Organic ultraviolet stabilizers, zinc oxide stabilization, and UV catalyzed degradation are briefly reviewed.     

Effects of O3 and NO2 on the natural weathering of plasticized poly(vinyl chloride)

The aim of this work was to study the natural aging of plasticized poly(vinyl chloride) (PVC) stabilized with epoxidized sunflower oil and Ca/Zn stearates. For that purpose, PVC samples were exposed in Algiers (hot Mediterranean climate) in two sites where the concentration of atmospheric pollutants (NO₂ and O₃) was known for 2 years. Site I contained NO₂ and O₃, and site II contained only NO₂. Samples were taken off every four months and characterized (mechanical properties and chemical modifications). The results showed a drop in tensile properties and an increase in Shore D hardness. The UV–Visible spectra evidenced the formation of short polyenes. Chemical structures due to the degradation were evidenced by ATR and transmission FTIR spectroscopy. It was found that the combination of O₃ and NO₂ exerted the most deleterious effect. J. VINYL ADDIT. TECHNOL., 2011. © 2011 Society of Plastics Engineers