Isotactic polypropylene 470 INDEX

The isotactic polypropylene (iPP) was supplied by FiberVisions, Georgia, in the form of homopolymer pellets with a melt flow index of 35g/10 min (230 °C, 160 g) and a density of 0.91 g cm-3. The reinforcing filler was rice straw fibril and fibril aggregates (RSF) obtained from rice straw pulp fiber (Taonan paper and pulp company, Jihn ptrovinoe. North-east of China) that was cut to pass a screen (room temperature and relative humidity of 30%) with holes of 1 mm in diameter by a Willey mill before treatment. The maleated polypropylene (MAPP) was used as compatibilizing agent and Epolene G-3003 P has an acid number of 6 and a molecular mass of 125 722. 

The wood flour pjartides of 425 microns (40-mesh) in size were kindly donated by American Wood fibers (Schofield, WI) and are constituted predominantly with p>onderosa pine, maple, oak, spruce, southern yellow pine, cedar. The wood was oven dried at 100°C for 24 h before processing to remove moisture. The isotactic polypropylene matrix (PP) has a density of 0.9 g/cm and a melt flow index of 2.5 g/10 min, it was provided by Solvay Co. Polypropylene grafted with maleic anhydride (MAPP) with an approximate maleic anhydride (MA) content of 3 wt. % was purchased from Aldrich Chemical Company, Inc. (Milwaukee, WI). All ingredients were used as received. 

Isotactic polypropylene Malen P-F401 iPP, for extrasion, made by Orlen SA flow index 2.4-33.2 g/10 min, yield point in stretching 28.4 MPa, crystallinity level 95% ... 

Unlike polyethylene, which crystallizes in the planar zigzag form, isotactic polypropylene crgtaUizes in a helical form because of the presence of the methyl groups on the chain. Commercial polymers are about 90 to 95 percent isotactic. The amount of isotac-ticity present in the chain will influence the properties. As the amount of isotactic material (often quantified by an isotactic index) increases, the amount of crystallinity will also increase, resulting in increased modulus, softening poinL and hardness. 

In addition to polymerization time, the concentration of PES also influences the stereospecificity of the catalyst system (Table 4, Figure 3). The isotacticity of polypropylene obtained in absence of PES is found to be 72%. The addition of PES improves the isotactic index from 72 to 87%. Increase of Si/Al ratio up to 0.2 depresses atactic polypropylene formation by 70% and isotactic polypropylene by... 

In one study. X-ray diffraction, Fourier transform infrared (FTIR) spectroscopy and refractive index measurements were utilized to characterize the state of molecular orientation in one-way and two-way (bi-axially) drawn isotactic polypropylene (iPP) films [6]. It was shown that the use of all three techniques leads to much greater confidence in the orientation averages deduced than can be obtained by using any two of the techniques. It was observed that, with one-way drawing, the chain axes of both crystalline and amorphous regions orient towards the direction of drawing. The crystalline chains are more highly oriented than the amorphous chains and tend to orient towards the plane of the... 

First Polymer Series. The first series of polymers was investigated, in order to limit the interaction between an AFM probe and polymer surfaces to only the dispersion (London) component of the Van der Waals force. Adhesional forces were measured between a S10,t probe and a set of nonpolar polymers that provided a range of refractive indexes (as measured) polystyrene (1.582), isotactic polypropylene (1.501), poly(vinylidene fluoride) (1.407), and poly(tetrafluoroethylene-co-hexafluoropropylene) (1.348). The histograms of the pull-off forces, measured with a SiOx probe, are shown in Figure 2 and tabulated with the calculated values for adhesion energy in Table 1. 

We have found an extreme combustion behavior for a system polypropylene-polypropylene-co-polyethylene [238], It can be explained in terms of oxidative degradation of polymer materials. We studied the features of autooxidation and combustibility of blends of isotactic polypropylene (PP) and ethylene-propylene copolymers (PP-co-PE) as thin films (50-80 ). ASTM D2863 (ISO 4589 Part 2) was used to determine the oxygen index (LOI) for polymer films 140 by 52 mm. 

This method has been tested on thin films of isotactic polypropylene and may be transferred to other type of radiation-stable optical transparent polymers, where it is possible to change the refractive index at definite doze of gamma-irradiation and their large application in the optical engineering [17, 76]. 

Acronyms and variables cold crystalhzation (CC) cobalt molybdenum catalyst (CoMoCAT) chemical vapor deposition (CVD) dichlorobenzene (DCB) high-pressure carbon monoxide (HiPCO) isotactic polypropylene (iPP) melt crystalhzation (MC) melt flow index (MFl) poly( -caprolactone) (PCL) polydispersity index (PDD polyethylene (PE) polyethylene oxide (PEO) poly (ethylene-propylene-diene) [P(E-PP-diene)] poly(ethylene 2,6-naphthalate) (PEN) poly(ethylene terephthalate (PET) poly(L-lactic acid) (PLLA) poly(trimethylene terephthalate (PTMT) poly(vinyl alcohol) (PVA) 1,1,2,2-tetrachloroethane (TCE) tetrahydrofuran (THE) weight-average molecular weight = ] number-average molecular weight Avrami exponent for neat polymer = Avrami exponent for CNT composite = Avrami rate constant for neat polymer = Avrami exponent for composite = neat polymer crystalhzation... 

Non-Polar Polymers. The ability to distinguish between polymers of differing refractive index was tested 10) by measuring pull-off forces between a silica tip and a series of four non-polar polymer samples in perfluorodecalin (a non-polar, low-refractive-index liquid, =1.317) polystyrene (PS, =1.582), isotactic polypropylene... 

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... 

Fig. 16 The modification in a average numerical molecular weights and b dispersion indexes for (filled square) isotactic polypropylene, (filled diamond) syndiotactic polypropylene, (filled triangle) high density polyethylene...

The properties of isotactic polypropylene in its jS-crystalline form can be compared with commercial IPP of same grade in its a-crystalline form. The differences show up most clearly in impact resistance. The characteristic properties of two commercial grade polypropylene HGX330 and GP186 having melt flow index of 33 and 3 g /10 min, respectively, supplied by Phillips Petroleum Company in its a- and iS-form at room temperature are reported in Tabs. 1-3. 

Fortunately, the Herman orientation function, F, can be determined by a number of independent techniques, including X-ray diffraction, birefringence, sonic modulus, and refractive index measurements. These methods, coupled with IR dichroic measurements of absorption, can be used to calculate quantitative values for the transition-moment angles by using Eq. (2.15). A plot of F measured by X-ray diffraction versus (i — )/(/ -f 2) will be linear with a zero intercept. A least-squares evaluation of the data from this line will yield the slope, (/ o + 2)/(Ro — ) When is 0° (parallel to the molecular chain axis) the slope equals 1.0 and when equals 90°, the slope equals —2.0. A quantitative value of the transition-moment angle can then be calculated. Transition-moment angle measurements have been published for isotactic polypropylene and some of the results are as follows [22] ... 

The isotactic polypropylene and polystyrene were obtained from The Dow Chemical Company. The PP used was Dow ZN5D98 having a bulk density of 0.900 g cm and melt flow index of 3.4 g per 10 min. The PS used was Dow STYRQN 685D having a bulk density of 1.040 g cm and melt flow index of 1.5 g per 10 min. 

The properties of commercial polypropylene vary widely according to the percentage of crystalline isotactic polymer and the degree of polymerization. Polypropylenes with a 99% isotactic index are currently produced. 

Polypropylene is characterised by isotactic index which is percentage of polymer not dissolving in boiling, n-haptane Commercial polypropylenes are having isotactic index of 95-98 per cent. 

ISO 9113 1986 Plastics - Polypropylene (PP) and propylene-copolymer thermoplastics -Determination of isotactic index... 

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