PP Materials Research Articles

Determination of a polymeric hindered amine light stabilizer in polypropylene formulated with magnesium hydroxide flame retardant by reactive thermal desorption-gas chromatography.

A polymeric hindered amine light stabilizer (HALS), Tinuvin 622 (MW [symbol: see text] 4000), in PP materials formulated with a magnesium hydroxide flame retardant was determined by reactive thermal desorption (RTD) gas chromatography (GC). Two kinds of the HALS components that were formed through the RTD in the presence of tetramethylammonium hydroxide [(CH3)4NOH, TMAH] were clearly observed in the chromatograms of the PP samples, with negligible interference from the other additives and the PP substrate. Here, the coexisting flame retardant was proved to affect significantly the RTD process of the occluded HALS. As a result, the recovery of the HALS components in the RTD-GC chromatograms of the PP samples increased with increase in the content of the flame retardant. This enhancement of the HALS recovery is attributed mainly to the preferential exposure of the HALS on the surface of the ground PP sample through the interaction between the polymeric HALS and the flame retardant in the molten PP during kneading. In spite of such a considerable action of the flame retardant, the observed intensities of the characteristic peaks of HALS by RTD-GC showed a good linear relationship with the HALS content in the PP samples with constant content of the flame retardant (50 phr); this relationship could be used as the calibration line for the determination of the polymeric HALS in the PP materials containing the flame retardant.

Study on the thermoplastic vulcanizate using ultrasonically treated rubber powder

AbstractNowadays, waste EPDM (ethylene propylene diene monomer) increasingly has been causing significant environmental problems with increasing numbers of vehicles. From the perspective of the environment and economics, recycling is the best method to treat waste materials. This study investigated waste EPDM/PP (polypropylene) blends with waste EPDM. Waste EPDM powders were treated ultrasonically, which physically modifies the rubber particles to confer good mechanical properties. Also investigated were the relevance of the mass percentage of the dispersed phase, the influence of the geometry and rotation speeds of the screw used in extrusion, and the melting temperature of PP materials on the morphology and mechanical properties of the blend. The purpose of this study was to develop a valuable thermoplastic elastomer from waste EPDM. This study concentrated on determining the optimum conditions for producing a blend by extrusion, including parameters of screw geometry, screw rotational speed, and operating temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2503–2507, 2003

Structural change of a polymeric hindered amine light stabilizer in polypropylene during UV-irradiation studied by reactive thermal desorption-gas chromatography

The structural changes of a polymeric hindered amine light stabilizer (HALS), Adekastab LA-68LD (MW=1900) added in PP materials during UV-irradiation were investigated by reactive thermal desorption-gas chromatography (RTD-GC) in the presence of tetramethylammonium hydroxide [(CH3)4NOH, TMAH]. Not only the products formed from the residual intact HALS, but also those from its oxidized moiety (nitroxyl radical) were observed on the resulting chromatograms without the use of any troublesome sample pretreatment such as solvent extraction. The changes in the yields of these key products were then examined as a function of UV-exposure time. As a result, it was revealed that the amount of the nitroxyl radical increased in the initial stage of UV-irradiation but then slightly decreased mainly because of further decomposition into the smaller compounds, whereas that of the intact HALS monotonously decreased during exposure.

The research on aggregation structure of PP materials under different condition and the influence on mechanical properties

In this article, the study of the aggregation structure of PP material with the IAS4 Image Analysis System is reported. The result indicates that the morphology of spherulite or filling particle in the matrix of crystalline polymer can be quantitatively described by the IAS4 Image Analysis System. Through the measurement of the aggregation structure, the transformation of mechanical properties was explained. With the increase of filling quantity of nucleating agent, the crystallinity ( X c ) tends to increase, the spherulite size ( D n ) and its distribution ( C d ) tends towards decline. The different heat treatment technology influenced only the crystallinity but not the spherulite size or its distribution. The effects of X c , D n and C d on mechanical properties were investigated. It was shown that, with the decrease of X c , D n or C d , the notch impact strength increases. To the PP/talc composite, the aggregation of talc particle has relation with the original size of particle, filling quantity and the surface treatment level. With the decrease of particle size or uniform distribution, the notch impact strength rises up.

Experimental investigation of the morphology development and mechanical properties of waste ethylene propylene diene monomer/polypropylene blend in modular intermeshing corotating twin‐screw extruder

AbstractNowadays, with the increase in the number of automobiles, waste EPDM (ethylene propylene diene monomer) is causing a significant environmental problem. From environmental and economical perspectives, recycling is one of the popular methods to solve environmental problems. This study, which involved waste EPDM/PP (polypropylene) blends with the ratio range of 70/30 and 75/25, set out to ascertain the relevance of the mass percentage of the dispersed phase, the influence of the screw geometry, the screw rpm, and the melting temperature of PP materials on the morphology and mechanical properties of the waste rubber blend. The purpose of this study is to develop a high‐value thermoplastic elastomer from waste EPDM. This investigation concentrated on determining the optimum conditions for producing a blend by extrusion, relative to screw geometry, screw rational speed, and operating temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2276–2282, 2002

CRYSTALLIZATION BEHAVIOR OF PP IN A NEW GENERATION OF COMPOSITE MATERIAL

The microstructure of isotactic polypropylene (iPP) has been investigated during different steps of the processing of commingled PP/unidirectional glass fiber composites. From wide angle x-ray scattering and differential scanning calorimetry analysis, complemented by density measurements, it can be concluded that the crystalline phase in both un-reinforced PP and composite materials is only constituted of the α phase. The morphology of the crystalline phase and the two-dimensional geometric arrangement of fibers within the matrix of commingled composites reinforced by 45, 60, and 75 wt% of fibers have also been investigated using optical microscopy. The composites exhibit heterogeneous morphology whatever the fiber content is. Moreover, large spherulites can be distinguished, but the presence of a transcrystalline phase around the fibers cannot be detected.

Development of non-compounded high stiffness and high impact resistance material for interior parts

PP materials for interior trims which require different physical properties were produced by adding an optimized talc master batch to the molding process. The parts used in this material have enough stiffness and impact resistance. With this new production process the interior trim materials are easier to recycle and the cost of the door trim was reduced. This paper describes how the required properties were achieved with the addition of a talc master batch.

Crystallization of controlled rheology type polypropylene

Investigation of the crystallization behaviour of polypropylene samples of various molecular weights prepared by peroxide melt degradation of commercial polymers has shown that the spherulite growth rate does not depend on a molecular weight. The degraded and initial PP materials were crystallized in the same manner in regimes II or III according to the crystallization temperature. The II–III regime transition took place at T c=137°C. The overall crystallization rate was controlled by the number of heterogeneous crystallization nuclei. The dependence of nuclei number on the molecular weight of the degraded samples exhibited a flat minimum in the range of medium molecular weights. It was proposed as an explanation of this minimum assuming two competing processes for the probability of attachment of the polymer chain to the solid surface of heterogeneity present in the polymer: decreasing probability for shorter chains and increased probability for more polar chains.

Optimum mixtures of stabilizers for polypropylene monofilaments and films

The joint use of antioxidants of the phenolic type and SHA causes manifestation of an antagonistic action. By choosing optimum dosages of the stabilizers, this adverse effect can be reduced to a minimum. The fundamental possibility of replacing the imported stabilizers Tinuvin 327, Cyasorb UV-531, and Irganox 1010 by the domestic products diacetam 5, benzon OA, fenozan 23, and fenozan 28 in the production of PP and fibrous materials based on it has been demonstrated. In a complex of properties, the most effective mixed composition in articles based on PP is the one which contains diacetam 5 (0.2% by wt.) fenozan 23 (0.1% wt.), phosphite NF (0.2% by wt.), and DSTDP (0.2% by wt.).