Weathering performance

The ability to downgauge, decrease part weight, improve barrier properties and reach new levels of product performance are propelling polyolefins into new markets previously dominated by other plastics. The high growth rate in PP production capacity is mainly being driven by the ability of PP to replace other resins on a cost/performance basis. For example, functionalisation of PP by incorporation of acrylic functionality has extended its weatherability performance. Interpolymer competition will have a significant impact on the amount and type of additives used. 

The results from this study support what has been dealt with throughout the text and especially focused on in Chapter 5 the concept s ability to predict wastewater quality changes in a sewer. The example shows that the corresponding process model can be used to simulate the average dry-weather performance of the sewer and serve as a tool for process design and management. The sewer, with its relation to the subsequent treatment plant, is generally... 

The text deals with the microbial and chemical process engineering of sewer networks. It emphasizes dry-weather processes and not the wet-weather impacts that are primarily controlled by physical processes. Under such conditions, the physical in-sewer processes in terms of, for example, hydraulics, sediment and biofilm erosion and solids transport are important. A quite different approach must be applied when wet-weather conditions in sewers dominate. However, wet-weather performance of sewers also requires that sediment deposition be dealt with during dry-weather periods. 

Briefly expressed, the sustainable approach of the sewer process concept can be interpreted by changing wastewater management from an end-of-pipe treatment to a pipe and plant treatment. This is not the only way of approaching a sustainable solution for an urban wastewater system, however, it is a contribution. But, it is certainly true that the sewer process concept tends to put much more focus on the dry-weather performance of the sewer than is typically done. 

Traditionally, books dealing with sewer systems have been devoted to hydraulics and pollutant transport phenomena. In this context, urban drainage and wet-weather performance, as well as the sewer s interaction with treatment plants and receiving waters, were main focal points. 

Figure 12.3 Examples of the weathering performance of (a) a stabilised HDPE nonwoven and (b) a polyamide/polyester nonwoven deliberately unstabilised against ultraviolet radiation. Both were exposed to artificial weathering using three different types of apparatus and to natural weathering in two locations. All results are plotted against radiant exposure (total ultraviolet light energy...

In point of fact, when considering the weathering performance of plastic materials, there exists even more interplay between weathering factors than the factors noted above, such as the ambient temperature, temperature of the actual specimens under exposure and the humidity during exposure of the materials. If the... 

Wood modification is a means of altering the material to overcome or ameliorate one or more of its disadvantages. The aim of a modification may be to bring about an improvement in decay resistance or dimensional stability, to reduce water sorption, to improve weathering performance and so on. The term wood modification applies to the application of a process that alters the properties of the material such that during the lifetime of a product no loss of the enhanced performance of the wood should occur. 

In addition to improved translucency with better colorability, an improved weathering performance can also be expected for the mixture compared to MMASAN alone and improved physical properties can be expected for the mixture compared to PMMA alone. Example formulations are shown in Table 12.3... 

An attempt to improve the weatherability performance has been to increase pigmentation, particularly TiC>2. However, this additive contributes to the overall opacity, and therefore reflectivity and weatherability, of the resultant exterior siding. 

Chemical Properties Optical Properties Weathering Performance Electrical Properties Thermal Stability... 

Two reports in the patent literature claim the invention of CFI additives specifically designed to improve the cold weather performance of biodiesel (Scherer and Souchik, 2001 Scherer et al, 2001). Block copolymers of long-chain alkyl methacrylates and acrylates were effective as PPD and flow improv-... 

CPE impact modifiers contain around 35% of chlorine and are thermoplastic in nature. With a similar melting point to PVC, they initially form a network structure which changes to a particulate structure on processing (134). They also have good processability and excellent weathering performance consequently they are also used for window profiles (287). The effect of residual... 

Black pigment selection for outdoor use has to consider weathering performance. Different infrared reflecting blacks have been evaluated in relation to heat build-up properties and actual weathering characteristics. The influence of free iron has also been examined (344). 

There are various accelerated light stability test methods available and/or exposure in harsher climates (Florida, Arizona) to test the weathering performance. The prediction of photoageing stability based on accelerated laboratory testing is very difficult, but some attempts have been made for PVC-P (445). The most relevant point is to use as reference a formulation known to have good outdoor weathering performance. 

Protection of exterior reconstituted panel products (in particular particle board) by surface coatings, treatments and overlays, and subsequent weathering performance, has received considerable attention (J, JJ, 74, J33, 153-155, 157-159), Painted and overlaid boards are much more durable than unfinished boards. Addition of wax as a water repellent benefits performance of the boards, but does not protect against water vapor (J, 11, 74). 

In order to reconstruct the process of chemical weathering, it is necessary to select a substance in the source rock and resultant soil that can be considered relatively inert to weathering, with which concentrations of other soil constitutents can be compared. AI2O3 and Ti02 have been used for such purposes. Once an inert "tracer has been selected, how is such an analysis of weathering performed ... 

RANKING OF THE WEATHERING PERFORMANCE OF POLYMER/MIRROR ASSEMBLIES... 

Lange SE, RoweU RM. Weathering performance of aspen-polypropylene composites. Proceedings of the 7th International Conference on Woodfiber-Plastic Composites, 2003 Madison, WI. Wisconsin Forest Products Society 2004. p 317. 

Using CPE-25 opens new possibilities not available with CPE-36. It gives faster fusion and enhanced melt strength without reduction of impact strength and weathering performance. 

Lead stabilizers are still used for this production in Europe but replacement Ca/Zn stabilizers are available and their weathering performance is better than that provided by traditional lead stabilizers. 

Climates can be classified into a number of types such as temperate, subtropical, desert, arctic and Mediterranean [2]. Additionally, they can be industrial, rural or marine in nature. The effects of weathering will vary in each of these, as well as from season to season and from year to year. How, then, can the weathering performance of one material be defined and compared with that of another The short answer is that it is extremely... 

The constitution of the unsaturated polyester resin used to make a gelcoat is obviously a prime factor in determining its weathering performance. Base polyesters (which are subsequently dissolved in the monomer) are made by reacting together saturated and unsaturated diacids and diols, and variation of these ingredients enables properties such as flexibility, heat distortion... 

Features Cost-effective extreme toughness, abrasion/mar resist. exc. water/chem. resist., exterior weathering performance broad adhesion crosslinkable to enhance performance Properties Dens. 8.7 Ib/gal vise. 50-250 cps soften, pt. 305 F pH 8-9.5 VOC 0.42 Ib/gal hardness (Sward) 52 40 01% solids Hauthane HD5004 [C.L. Hauthaway]... 

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