Polypropylene, minerals

Ferrex. (Ferro] Polypropylene, mineral-fllled for high gloss applies. 

Besides, a decrease in the critical particle size for the polymer/polymer systems could also be obtained due to the decrease in the Weber number values, caused by an increase in the interfacial area available. A saturation level at the interaction plane across the interphase and in the concentration of the interfacial modifiers also emerges from the finite dimensions of the interphase. Above a critical concentration, the interfacial modifier could form its own phase, and then a nth phase ought to be considered in the studies rather than a model based on modified interfaces. Following sections show some examples of the role of the interfacial modifiers from the matrix side for both rigid and nondeformable dispersed phase polypropylene/mineral reinforcement system and polymer/polymer binary system based on polypropylene and polyamide 6. 

As waxes are a relatively expensive raw material, in the production of cosmetics and candles they have been replaced by mineral hydrocarbon fractions (paraffin), solid triglycerides (tristearin, also known as stearin) or by various synthetic materials (polyethylene and polypropylene). Mineral waxes are used almost exclusively for non-food purposes. The so-called montanic acid esters and oxidised polyethylene wax can also be used to modify the surfaces of fresh citrus fruits. Montanic acid esters are used pharmaceutically to improve the retardation of drug release from tablets. 

Polypropylene polymers are typically modified with ethylene to obtain desirable properties for specific applications. Specifically, ethylene—propylene mbbers are introduced as a discrete phase in heterophasic copolymers to improve toughness and low temperature impact resistance (see Elastomers, ETHYLENE-PROPYLENE rubber). This is done by sequential polymerisation of homopolymer polypropylene and ethylene—propylene mbber in a multistage reactor process or by the extmsion compounding of ethylene—propylene mbber with a homopolymer. Addition of high density polyethylene, by polymerisation or compounding, is sometimes used to reduce stress whitening. In all cases, a superior balance of properties is obtained when the sise of the discrete mbber phase is approximately one micrometer. Examples of these polymers and their properties are shown in Table 2. Mineral fillers, such as talc or calcium carbonate, can be added to polypropylene to increase stiffness and high temperature properties, as shown in Table 3. 

Polypropylene can be fabricated by almost any process used for plastics (see Plastics processing). The extmsion of pipe and injection mol ding of fittings present no unusual problem. However, there is no way to bond the fittings to the pipe except by remelting the polymer, which is impractical on most constmction sites. The resin can be reinforced by glass fibers, mineral fillers, or other types of fillers and can be pigmented readily. 

Polypropylene Polypropylene (PP) pipe and fittings have excellent resistance to most common organic and mineral acids and their salts, strong and weak alkahes, and many organic chemicals. They are available in sizes V2 through 6 in, in Schedules 40 and 80, but are not covered as such by ASTM specifications. 

Polypropylene has a chemical resistance about the same as that of polyethylene, but it can be used at 120°C (250°F). Polycarbonate is a relatively high-temperature plastic. It can be used up to 150°C (300°F). Resistance to mineral acids is good. Strong alkalies slowly decompose it, but mild alkalies do not. It is partially soluble in aromatic solvents and soluble in chlorinated hydrocarbons. Polyphenylene oxide has good resistance to ahphatic solvents, acids, and bases but poor resistance to esters, ketones, and aromatic or chlorinated solvents. 

In appearance and on handling the material is somewhat intermediate between a wax and a rubber. It is also semi-tacky. Like isotactic polypropylene it is attacked by oxygen but unlike the isotactic material it swells extensively in aliphatic and aromatic hydrocarbons at room temperature. It is also compatible with mineral fillers, bitumens and many resins. 

It has been found that, for a fixed mineral filler content, the viscosity of PMF-based composites increases when the coat is made of polyethylene [164, 209, 293], poly(vinyl chloride) [316] and polypropylene [326, 327], The picture was different, however, for composites based on the ethylene/vinyl acetate copolymer to which kaolin with grafted poly (vinyl acetate) was added [336]. Addition of PMF with a minimum quantity of grafted polymer results in a sharp drop of flowability (rise of viscosity), in comparison to addition of unmodified filler but with a further increase of the quantity of grafted polymer the flow gradually increases and, depending on the kaolin content and quantity of grafted polymer, may even become higher than in specimens with unmodified filler, for equal concentrations. 

Between 250 and 450°F (121 and 232°C), plastics used include glass or mineral-filled phenolics, melamines, alkyds, silicones, nylons, polyphenylene oxides, polysulfones, polycarbonates, methylpentenes, fluorocarbons, polypropylenes, and diallyl phthalates. The addition of glass fillers to the thermoplastics can raise the useful temperature range as much as 100°F and at the same time shortens the molding cycle. 

Homopolymerisation which accompanies copolymerisation increases at higher styrene concentrations, thus the grafting efficiency decreases with increasing styrene concentration (Table V). These results are similar to analogous data for polypropylene (5, 6). Inclusion of mineral acid increases homopolymerisation, however not to the same degree as it enhances copolymerisation, thus, overall, grafting efficiency is significantly improved in the presence of acid. 

M. LeBras., Mineral fillers in intumescent fire retardant formulations - Criteria for the choice of a natural clay filler for the ammonium polyphosphate/pentaeythritol/polypropylene system, Fire and Materials, vol. 20, pp. 39-49,1996. 

Table 3.5 shows some examples of the property effect ratios for mineral filler-reinforced polypropylene. The effect ratio is the performance of the reinforced polymer divided by the performance of the neat polymer. Properties of low-level glass fibre reinforced polypropylene are given for comparison. 

Table 3.5 Examples of the effect of mineral fillers on polypropylene properties...

These results are of the same order as those in Table 3.5 for mineral-filled polypropylene. Versus neat polymer ... 

In most, but not all, cases the incorporation of mineral fillers at the levels needed to produce useful effects causes a significant decrease in the toughness or impact strength of the composite. The major exception is in polypropylene, where certain types of calcium carbonate can give a very significant increase in toughness at loadings of 30-40 wt% [33]. 

Frothers are chemicals whose molecules contain both a polar and a nonpolar group. The purpose of a froth is to carry mineral-laden bubbles lor a period of lime until the froth can be removed from the flotation machine for recovery of ils mineral content. Typical frothing chemicals are alcohols, cresylic acids, eucalyptus oils, camphor oils, and pine oils, all of which are slightly soluble in water. Soluble frolhers in common use include alkyl ethers and phenyl ethers of propylene and polypropylene glycols. 

On low energy surfaces such as polyethylene, polypropylene, or polytetrafluoroethylene many liquids have finite contact angles and Tre values are generally zero (3). On high energy surfaces such as most mineral oxides most liquids have no contact angle, tt6 values are quite appreciable and... 

Polyolefins. Polyethylene (conventional and linear) and polypropylene have excellent chemical resistance and are readily molded and machined, although they are rather soft. Conventional polyethylene adheres well to metals, and polyethylene tubing can be readily sealed around metal rods and wires to make simple electrodes suitable for use at temperatures below 60°C. The material is resistant to mineral acids and bases (except concentrated sulfuric and perchloric acids) and most organic solvents except halogenated or aromatic hydrocarbons. 

Bertelli, G., Goberti, P., Marchini, R., Camino, G., and Luda, M.P., Combined melamine/mineral fillers as fire retardants for polypropylene, Proceedings from 6th European Meeting on Fire Retardancy of Polymeric Materials (FRPM 97), Lille, France, 1997, p. 34. 

Polymer manufacturers offer paintable grades of polypropylene or copolymer blends with talcum or other mineral fillers with such grades the tolerance of over-treatment seems to be increased—which can be advantageous, especially with flame treatment. 

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