Property—processing-cost performance

PBAs are designed explicitly to meet the needs of specific applications on the basis of their property-processing-cost performances. One polymer is incorporated into the matrix of other polymers to impart specific characteristics as per the requirement along with the appropriate compatibilizer to ensure stress transfer in between phases. The polymer blend constituents and composition must, therefore, be selected on the basis of the compensation of properties, considering the advantages and disadvantages associated with each phase. Table 12 indicates some of the components used as modifiers. 

Why Blend All new materials attract interest on the basis of their property-processing-cost performance. With regard to properties, polymer blends can be expected to exhibit any of the following three possibilities for a given property. 

While dispersant hydrocarbon backbones are currently dominated by conventional polyisobutylene, many more backbones are on the horizon with the potential to provide improved properties, processing, overall performance per cost, and the ability to optimize properties to respond to specific engine performance characteristics. Some of these (Fig. 8) include high vinylidene PIB, olefin copolymers (OCP) and poly-alpha olefins (PAO). Each of these will be discussed in terms of their structure and reactivity, physical properties and how these translate into strengths and weaknesses in the final application. 

Optimize design to reduce cost or satisfy functional and performance requirements General configuration Configuration proportions such as rib depths, shell radii, fillet radii, etc. Material thickness Material alternatives—consider additives to tailor properties Process alternatives... 

Both techniques have their advantages and their limitations with respect to process time, process temperatures, and process costs. However, the crucial question is How much does crosslinking contribute to the desired properties of the material The performance of the final product is, of course, the major issue. A lot of information on crosslinked polymers is available in the literature. There have been several attempts in the past [1-7], and also more recently [8-10], to sort out this accumulation of scientific data. Yet, it is neither simple nor particularly rewarding to undertake such a venture due to the multitude of variables which make direct comparisons difficult, and to the incidence of apparent contradictions. 

Selecting a flame retardant for an adhesive system has many ramifications, depending on the formulation being modified, the end use, how it will be processed, and the cost/performance ratio. When one is choosing a flame retardant, characteristics such as water extraction, particle size, viscosity, toxicity, dusting, uniformity, as well as economics must be considered. The materials chosen to perform the function of flame retardation must not interfere with the final product s performance. The major problem with incorporating flame retardants in adhesives is that very often a significant amount is required, and they interfere with the other properties of the adhesive and contribute to the cost. This is why bromo bisphenol epoxy resins are often employed in flame-retardant epoxy adhesives. 

At the moment, there are a growing number of biodegradable polymers performing well in niche applications. Many of these materials can be even more cost competitive in the future compared to petroleum-based resins including PET, polyethylene (PE), and polypropylene (PP) as suppliers develop better material properties that can lead to thinner films or lower processing costs. 

The main groups of additives have already been listed in Section 2. PVC formulation technology depends on the correct combination of several of these additives to suit the processing and end-use requirements. A basic rigid PVC-U formulation will contain medium to low molecular weight resin plus lubricant and heat stabiliser. Other additives will be included to improve processability and physical properties, give weathering resistance, improve cost performance, colour, etc. 

This work aims to produce mixed calcium carboxylate stabilisers for use in place of calcium stearate for the stabilisation of PVC. The new stabilisers are based on mixed salts of stearic acid with derivatives of phthalic or maleic acid and also with branched alpha, alpha-branched carboxylic (C12-C16) acids, noted for their lower cost and adequate effectiveness. Test results are examined in detail for the performance of these stabilisers in terms of service properties, processability, and stabilising action. 2 refs. (Translated from Plasticheskie Massy, No.5, 2000, p.19)... 

Improvement in cost, processability, and performance of polymers can also be achieved through blending two or more polymers. The blends may be homogeneous, heterogeneous, or a bit of both. Properties of miscible polymer blends may be intermediate between those of the individual components (i.e., additive behavior), as is typically the case for Tg. In other cases, blend properties may exhibit either positive or negative deviation from additivity. 

The combination of SHAC catalyst and SHAC ADT enables Dow s catalyst systems to achieve low cost and easy production of polypropylene polymer with superior properties. The exceptional performance of the SHAC catalyst systems also finds applications in other PP processes. 

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