Polymer compounds polypropylene

Substitute for Conventional Vulcanized Rubbers, For this application, the products are processed by techniques and equipment developed for conventional thermoplastics, ie, injection molding, extrusion, etc. The S—B—S and S—EB—S polymers are preferred (small amounts of S—EP—S are also used). To obtain a satisfactory balance of properties, they must be compounded with oils, fillers, or other polymers compounding reduces costs. Compounding ingredients and their effects on properties are given in Table 8. Oils with high aromatic content should be avoided because they plasticize the polystyrene domains. Polystyrene is often used as an ingredient in S—B—S-based compounds it makes the products harder and improves their processibility. In S—EB—S-based compounds, crystalline polyolefins such as polypropylene and polyethylene are preferred. Some work has been reported on blends of liquid polysiloxanes with S—EB—S block copolymers. The products are primarily intended for medical and pharmaceutical-type applications and hardnesses as low as 5 on the Shore A scale have been reported (53). 

Costa, L. Camino, G. Luda, M. P. Effect of the metal on the mechanism of fire retardance in chloroparaffin-metal compound-polypropylene mixtures, Polymer Degradation and Stability, 1986, 14(2), 113-123. 

Active and Inert Substrates. Since acrylonitrile, methylvinylpyri-dine, and mixtures of the two compounds all can be polymerized by (C2H5) oAlCl TiCl3 and benzoyl peroxide, it is desirable to study the free radical reaction in the presence of inert polypropylene powder and to compare its final product with the AFR polymerization under otherwise similar conditions. Deactivated, dry polypropylene powder in hexane suspension was treated with (C2H5)oAlCl-TiCl3, methylvinylpyri-dine, acrylonitrile, and benzoyl peroxide in a prescribed manner. The results are summarized in Table VII. When deactivated dry polypropylene powder was treated with monomers and peroxide, the amount of insoluble polar copolymer decreased as free radical temperature decreased, while for AFR polymer (active polypropylene) this amount of insoluble polar copolymer increased as temperature decreased. The polymerized comonomers in the active polymer were much less extractable than in the inert powder. 

The production and applications of polymers have gradually developed, gaining ground in many fields. The main classes of polymers, namely polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene and polyethylene terephthalate are produced in millions of tonnes annually [1]. There are many methods of polymer synthesis free-radical polymerisation (bulk, solution, emulsion and suspension), condensation polymerisation, ethoxylation, polymer compounding and formulations involving solvents, fillers, pigments and so on. Besides the high volume consumption of these common plastics, the demand for polymers with specific end-use properties has increased. 

Fritz, H.G. and Stoehrer, B. (1986) Polymer compounding process for controlled peroxide-degradation of polypropylene. Int. Polymer Processing, 1, 31-41. 

A modified polymer, also called a semisynthetic polymer, is a natural polymer compound treated by a chemical reaction. The world s first man-made polymer material—cellulose nitrate—was made from natural cellulose, such as cotton or cotton cloth, that was treated with concentrated nitric acid and concentrated sulfuric acid. A synthetic polymer is a polymer compound synthesized by small molecular weight compounds through chemical methods. Examples of synthetic polymer materials are plastics such as polyethylene, polypropylene, and polyvinyl chloride and fibers such as polyester, nylon, and other synthetic fibers. 

Lappin and Zannucci determined 4-(dodecyloxy)2-hydroxybenzophenone (DOBP) and 2,6-di-tert-butyl-p-cresol (BHT) in polypropylene by this technique (Table 1.4). The precision of the BHT determination is good but the quantity found (0.02%) was less than the amount added (0.05%) possibly due to some losses of volatile BHT during polymer compounding. DOBP determinations ranged from 0.20 to 0.35% for a sample originally containing 0.30% of the additive. 

Emcamide was compounded with two polymers isotactic polypropylene, i-PP, (6 = 16.43 (J/cm ) ) and polyamide-12, PA-12 (6=21.67 (J/cm ) ). From these data it can be calculated that the absolute difference between the solubility index of emcamide and solubility indices of i-PP and PA-12 is 3.36 and 1.88, respectively. The difference indicates that emcamide is not readily soluble in any of the two polymers (the difference of solubility indices close or larger than 2). It is also expected that... 

Surface treatment of caldte with stearic acid significantly reduces the viscosities and yield values of molten polymer compounds [4,5]. Small CaCOj particles are commercially treated with stearic add to improve their processability. Suetsugu and White [5] have investigated stearic acid effects on a calcite-filled system. They found an increasing order of reduction with decreasing particle size and decreasing shear rate. K. J. Kim and White studied the effect of stearic add on caldte and on talc particles in a polypropylene (PP) matrix [9 to 11 ]. 

Worldwide, ready-to-be-processed CaCOg filled polymers are available from a number of compounders. Polypropylene compounds, in the 10-40%wt range are available from numerous producers and grades up to 50%wt are also locally offered for special applications. Table 6.8 gives the average properties of typical commercial PP-CaCOg composites, as compiled from manufacturers data sheets (when available). 

This type of adhesive is generally useful in the temperature range where the material is either leathery or mbbery, ie, between the glass-transition temperature and the melt temperature. Hot-melt adhesives are based on thermoplastic polymers that may be compounded or uncompounded ethylene—vinyl acetate copolymers, paraffin waxes, polypropylene, phenoxy resins, styrene—butadiene copolymers, ethylene—ethyl acrylate copolymers, and low, and low density polypropylene are used in the compounded state polyesters, polyamides, and polyurethanes are used in the mosdy uncompounded state. 

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. 

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