Polypropylene thermal properties

Table 11.1 Some mechanical and thermal properties of commercial polypropylenes...

As shown in the previous section the mechanical and thermal properties of polypropylene are dependent on the isotacticity, the molecular weight and on other structure features. The properties of five commercial materials (all made by the same manufacturer and subjected to the same test methods) which are of approximately the same isotactic content but which differ in molecular weight and in being either homopolymers or block copolymers are compared in Table 11.1. 

Isostatic molding, 18 300 Isostatic refractory pressing, 21 504 Isostearic acid, physical properties, 5 35t Isotachophoresis, 9 738, 742, 748 Isotacticity, of polypropylene, 20 529 Isotactic PB resins, thermal properties of, 20 417... 

Blends of poly (ethylene terephthalate) (PETP) and polypropylene (PP) with different rheological properties were dry blended or compounded, and extrusion foamed using both physical blowing and chemical agents, and the foam properties compared with those of foam produced from the individual components in the absence of compatibilisers and rheology modifiers. The foams were characterised by measurement of density, cell size and thermal properties. Low density foam with a fine cell size was obtained by addition of a compatibiliser and a co-agent, and foamed using carbon dioxide. The presence of PP or a polyolefin-based compatibiliser did not effect... 

This mixed product consists of small, platy particles with a relatively high surface area (15-20 m g ). The principal interest has to date been as a flame retardant Aller, principally for polypropylene. Both component phases decompose endothermically with the release of inert gas at relatively low temperatures. They are stable enough to allow incorporation into polymers such as polypropylene, but not polyamides. The performance of the two phases alone and in combination in polypropylene has been reported [91]. As expected from their thermal properties, hydromagnesite was the more effective flame retardant. The decomposition pathway of hydromagnesite has been shown to be considerably affected by pressure and this may affect its flame retardancy [71]. 

Fichera, A. and Zannetti, R. Thermal properties of isotactic polypropylene quenched from the melt and annealed. Makromol. Chemie 176, 1885 (1975)... 

The most common advanced composites are made of thermosetting resins, such as epoxy polymers (the most popular singlematrix material), polyesters, vinyl esters, polyurethanes, polyimids, cianamids, bismaleimides, silicones, and melamine. Some of the most widely used thermoplastic polymers are polyvinyl chloride (PVC), PPE (poly[phenylene ether]), polypropylene, PEEK (poly [etheretherketone]), and ABS (acrylonitrile-butadiene-styrene). The precise matrix selected for any given product depends primarily on the physical properties desired for that product. Each type of resin has its own characteristic thermal properties (such as melting point... 

On mechanical rather than thermal properties, plastics which were harder were also more difficult to cut and to fabricate satisfactorily. Chemically, plastics which resisted organic solvents were also more difficult to print safely and with good results, and so forth. Often, in practice, intractable properties were modified to the required degree by the inclusion of small amounts of other monomers (vinyl acetate in vinyl chloride a-olefins in polypropylene, etc.)—just as an unwanted property like brittleness in polystyrene was ameliorated by adding to it styrene-butadiene. 

Polypropylene is also used in a number of blends, some of them with applications in rubber industry, automotive industry, home constructions, etc. Some of the copolymers and blends used in rubber industry are vulcanized. Studies on thermal properties and pyrolysis of these copolymers and blends are common in literature [97, 105,110-118]. 

Pezelj E, Cunko R and Andrassy M, The influence of repeated maintenance treatments on chemical and thermal properties of polypropylene fibers 78th World Conference of the Textile Institute, 5th Textile Symposium ofSEVE and SEPVE, volume HI, 395-400, Thessaloniki, Greece, 1997. 

The storage modulus for the cured resins with different polypropylene carbonate contents (Fig. 21.20) did not change over the temperature range lower than their a-relaxation, compared with the parent epoxy resin. This implied that the epoxy matrix was toughened by the addition of PPC at no expense of its modulus but with a sacrifice to its thermal properties. The molecular weight of polypropylene carbonate... 

Analogous results have been recently obtained by other research groups. The effect of -COOH- and phenol-functionalized CNTs on mechanical, dynamic mechanical and thermal properties of polypropylene (PP) nanocomposites were considered, and the results confirmed in both cases that the percentage crystallinity was found to increase on phenol and carboxylic functionalization of MWNTs. 

With 10-40 % by weight short glass fibers (length 0.01-0.5 mm mean length of glass fibers approximately 0.2 mm) mixed into, for example, polypropylene, the mechanical and thermal properties of the material can be improved to such an extent the applications listed above, often in housings and casings, can be realized. 

The average length of the polymer chains and the breadth of distribution of the polymer chain lengths determine the main properties of PP. In the solid state, the main properties of the PP reflect the type and amoimt of crystalline and amorphous regions formed from the polymer chains. Polypropylene has excellent and desirable physical, mechanical and thermal properties when used in room temperature applications. It is relatively stiff and has a high melting point, low density and relatively good resistance to impact. 

In recent years polypropylene (PP) nanocomposites have attracted great interest in academia. The attractiveness of this new class of material hes in the large improvements in both mechanical and thermal properties, as well as in gas barrier and fire resistance (Grunes et al., 2003). Nanofillers, being additives of nanometre scale, are dispersed in PP matrix, offering multifunctional and high-performance pwlymer characteristics beyond those possessed by traditional filled materials. 

An example of a typical material composition is the combination of a polymer and a filler. Because compounding is a techiuque that can complement the drawbacks of conventional polymers, it has been studied over a long period and its practical apphcations are well known. Reinforcing materials such as short-fiber are often used for compounding with thermoplastic polymers in order to improve their mechaiucal or thermal properties. Polypropylene and polyamide (nylon) are used for the thermoplastic polymers, while glass fiber and carbon fiber are mainly used as reinforcing materials. A few ttm... 

EFFECT OF SYNDIOINDEX ON THE THERMAL PROPERTIES OF SYNDIOTACTIC POLYPROPYLENE. 

THERMAL PROPERTIES OF MELT AND SOLUTION CRYSTALLIZED ISOTACTIC POLYPROPYLENE. 

THERMAL PROPERTIES OE THE POLYPROPYLENE/MULTI-WALLED CARBON NANOTUBE COMPOSITES... 

A number of papers pointed at synthesis and research of thermal properties of nanocomposites (atactic polypropylene (aPP)/MWCNT) were reported [10-12]. It is remarkable that PP/MWCNT composites with minor level of nanocarbon content (1-5% by weight) were determined to obtain an increase in thermal and thermal-oxidative stability in the majority of these publications. 

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