Polypropylene nucleation

Luzenac talcs for polypropylene nucleation, supplier product guide (POL T GB 31 07). RioTinto Minerals. 

Figure 5.22. Impact strength of polypropylene nucleated by modified and unmodified zeolite vs. content of the nucleating agent. [Adapted, by permission, from Lv Z Wang, K Qiao, Z Wang, W,Mater. Design, 31, 3804-9, 2010.]...

Urea phenyl derivatives are used as polypropylene nucleating agerrls."" They give excellent crystallizability, high transmittance, high clarity, low haze, arrd irrrproved thermal stability.""... 

B Monasse. Polypropylene nucleation on a glass fibre after melt shearing. J Mater Sci 27 6047-6052, 1992. 

Term N J, Fairclough P A, Towns-Andrews E, Komanshek B U, Young R J and Ryan A J 1998 Density fluctuations the nucleation event in isotactic polypropylene crystallization Polymer 29 2381- 5... 

Polypropylene molecules repeatedly fold upon themselves to form lamellae, the sizes of which ate a function of the crystallisa tion conditions. Higher degrees of order are obtained upon formation of crystalline aggregates, or spheruHtes. The presence of a central crystallisation nucleus from which the lamellae radiate is clearly evident in these stmctures. Observations using cross-polarized light illustrates the characteristic Maltese cross model (Fig. 2b). The optical and mechanical properties ate a function of the size and number of spheruHtes and can be modified by nucleating agents. Crystallinity can also be inferred from thermal analysis (28) and density measurements (29). 

The consumption of 4-/ f2 -butylphenol in the production of phenohc resins represents an appHcation in a mature market and Htfle growth is projected. Its use in end-capping polycarbonates, in the production of glycidyl ethers, and in the production of nucleation agents for polypropylene is expected to grow at a rate above the growth of the GNP (see Table 3). 

Nucleating agents are used to improve the clarity of crystalline polymers such as polypropylene. Species such as diparamethyl-dibenzylidene sorbitol are... 

Many industrial semi-crystalline polymer materials like polypropylene, polyamides, or polyesters contain nucleating agents or clarifiers which form needle-shaped aggregates already in the polymer melt. "For this purpose the pattern is desmeared using the measured primary beam. For a less involved treatment it may be sufficient to know the integral width of the primary beam profile in fiber direction. 

Grein, G Toughness of Neat, Rubber Modified and Filled -Nucleated Polypropylene From Fundamentals to Applications. Vol. 188, pp. 43-104. 

Fig.l Differential scanning calorimetry (DSC) cooling scans from the melt, at 10°Cmin 1, of the following materials (from top to bottom) Isotactic polypropylene (iPP) iPP after self-nucleation treatment at TS = 162°C 80/20 polystyrene (PS)/iPP melt mixed blend 80/20 PS/iPP melt mixed blend after self nucleation treatment at Ts = 161 °C 80/20 PS/iPP unmixed blend (UB), see text and atactic PS homopolymer. (From [68] with permission)... 

Figure 7. Nucleation of isotactic polypropylene right unnucleated sample.

EFFECT OF NUCLEATING AGENTS ON POLYPROPYLENE FOAM MORPHOLOGY... 

EFFECT OF TALC ON CELL NUCLEATION IN EXTRUSION FOAM PROCESSING OF POLYPROPYLENE WITH CARBON DIOXIDE AND ISOPENTANE... 

Antec 96. Volume II. Conference proceedings. Indianapolis, 5th-10th May 1996, p.1941-7. 012 EFFECT OF BRANCHED STRUCTURE ON THE CELL MORPHOLOGY OF EXTRUDED POLYPROPYLENE FOAMS. I. CELL NUCLEATION... 

Addition of small amounts of nucleating agents influence the spherulitic crystallization of polypropylene and improve transparency (Sect. 1.3.3.3 and Example 3-20). 

In the crystallization of isotactic polypropylene from the melt, the number and size of the spherulites (and hence the rate of crystallization) can be influenced by the addition of certain nucleating agents.The smaller the spherulites, the greater is the transparency of the polypropylene film.The mechanical properties can also be affected in some cases. 

The effect of heterogeneous nucleation on the crystallization of isotactic polypropylene from the melt can be easily established as follows. A small amount of powdered polypropylene is well mixed with about 0.1 wt% of sodium benzoate in a mortar or by means of an analytical mill. Some of the mixture is transferred with a spatula to a microscope slide and melted at about 250 °C on a hot block. A cover slip is pressed on to the melt with a cork to obtain as thin a film as possible.The sample is held at 200-250 °C for some minutes and then allowed to crystallize at about 130 °C on the hot stage of the microscope an unadulterated polypropylene sample is crystallized in the same way. Both samples are observed under a polarizing microscope during crystallization,the difference in spherulite size between nucleated and untreated polypropylene can be seen very clearly. An ordinary microscope can also be used by placing polarizers on the condenser and eyepiece, and adjusting these to give maximum darkness. 

Galeski A (1995) Nucleation of polypropylene. In Karger-Kocsis J (ed) Polypropylene structure, blends composites, vol 1. Chapman Hall, London, p 116... 

The structure of crystalline polymers may be significantly modified by the introduction of fillers. All aspects of the structure change on filling, crystallite and spherulite size, as well as crystallinity, are altered as an effect of nucleation [9]. A typical example is the extremely strong nucleation effect of talc in polypropylene [10,11], which is demonstrated also in Fig. 2. Nucleating effect is characterized by the peak temperature of crystallization, which increases significantly on the addition of the filler. Elastomer modified PP blends are shown as a comparison crystallization temperature decreases in this case. Talc also nucleates polyamides. Increasing crystallization temperature leads to an increase in lamella thickness and crystallinity, while the size of the spherulites decreases on... 

Microstructure-property correlations in dynamically vulcanized thermoplastic elastomers based on polypropylene (PP)/EPDM have shown that clay was nearly exfoliated and randomly distributed into the continuous polypropylene phase [23]. SEM photomicrographs revealed that the size of rubber particles increased with clay incorporation. Also, the clay layers act as nucleating agents, resulting in higher crystallization temperature and reduced degree of crystallinity. 

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