Papers by Keyword: Polypropylene (PP)

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Authors: Xiu Yun Li, Li Yang, De Chun Liu
Abstract: The crystallization of isotactic polypropylene (iPP) and polypropylene/polyethylene-glycol (iPP/PEG) blends were investigated by in situ Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). It was found that the existence of polyethylene-glycol(PEG) does not destroy the helical structure of iPP in the melt, but changes the crystal structure of iPP in the bends. Moreover, the variation tendency of ratios of intensity A998 cm-1/A1460 cm-1 for iPP and iPP/PEG blends showed that the the onset crystallization temperature of iPP is improved by addition of PEG until the PEG content reaches to 5 wt%, and beyond this content, the crystallization point decreases.
Authors: Paulo E. Lopes, William T. Pennington, Michael S. Ellison
Abstract: Polymer crystalline regions can be characterized by wide-angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS). The in-situ study of isotactic polypropylene with measurement of wide angle and small angle X-ray scattering (WAXS and SAXS), at varying distances from the exit of the extruder have been successfully completed using an X-ray system with a standard X-ray source. The processing conditions, used were: 50, 100, 200 and 400m.min-1 for the take up speed, 0.3, 0.6, and 1.2 cm3min-1hole-1 for the melt flow rates, and a spinning temperature of 220°C. These experimental conditions produced draw down ratios ranging from 33 up to 1058. The X-ray characterization was carried in-situ at 15, 30, 45 and 60 cm from the exit of the spinneret and also ex-situ. The results obtained show the crystallinity index and the crystalline orientation to increase for the higher draw down rates, as expected under draw induced crystallization conditions, and a logarithmic relationship was observed within the experimental conditions used in this work. This communication reports the relationship between the crystallinity, crystalline orientation and lamellar long period and draw down ratio along the spin line.
Authors: Wen Cai Xu, Dong Li Li, Ya Bo Fu, Wei Shang
Abstract: The slip agents used to reduce coefficient of friction of polypropylene(PP) film, but it migrate brought the issue of food safety, to reduce of the corona effect and the peel strength of flexible film. We try another method to reduce the coefficient of friction. The result shown that the nano-modification not only reduces the coefficient of friction of PP, but also reduces the adsorption of volatile organic solvent in PP. The coefficient of friction of modified polypropylene was reduced by 50% when the concentration of nano-silica is between 1~2%. The final residues toluene in modified polypropylene was reduced to zero when the concentration of nano-silica in PP is between 1~3%. The modified polypropylene agrees quite well with food safety.
Authors: Shu Jun Liang, Jian Ping Deng, Lian Ying Liu, Wan Tai Yang
Abstract: A novel approach to functionalize polypropylene (PP) is presented. This method consists of two steps. Firstly, oligomers of glycidyl methacrylate (GMA) were synthesized via UV photo-polymerization using benzophenone (BP) as initiator. Secondly, the GMA oligomers were grafted onto PP, which was initiated by the free radicals generated through the reactivation of semipinacol dormant groups in the oligomers. By this method, the functionalization of PP could be facilely achieved in a simple system without either organic peroxide initiator or monomer; additionally, degradation of the substrate PP was not observed. This presentation is mainly focused on the characterization of the grafted PP products by XRD, DSC and TGA measurements. It is demonstrated that the melting temperature, crystallinity and the initial decomposition temperature of the grafted PP were all increased, compared with those of the origin PP; the functionalization of PP led to the change of the crystal form from the mixed form of α and β into only α form.
Authors: Mohd Hilmi Othman, Hasan Sulaiman, Md. Saidin bin Wahab
Abstract: This paper presents a review on the preparation, processing, properties and the recent applications of polypropylene-nanoclay nanocomposites. The material has attracted many researchers to explore more about the processing techniques, optimizations, and mainly the potential applications reflecting the advantages of these promising materials. The review consists of preparation of nanocomposites master batch, properties such as mechanical and thermal properties the effects of compatibilizers and clay content, as well as the recent application of these composites. The findings of this review might lead to more curiosity and investigating regarding to the above matters.
Authors: Yi Ming Sun, Dan Peng, Man Li
Abstract: Ramie fibers were incorporated into polypropylene as the reinforcement fillers. The transesterification between the hydroxyl groups of ramie fiber and the ester of maleic anhydride was employed to improve the compatibility of ramie fibers and the polypropylene matrix. The morphology of the composite surfaces and interfaces were studied using IR and SEM. The mechanical properties and water absorption of the composites were investigated. The results demonstrated that the esterification occurred on the surface of ramie fiber, due to which the compatibility between fiber and matrix treated was greatly improved. Because of the improved compatibility, the mechanical strength of the composites increased; while water absorption decreased.
Authors: Nai Xiu Ding, Li Li Wang, Mao Sheng Zhan, Liang Liu, Shuai Feng Xu
Abstract: In this paper, Carbon black was activated using titanate-type coupling agent, and then filled into polypropylene to prepare conductive composites, whose alternating current (AC) electrical properties, including impendence Z, phase angel θ, dielectric constantε and dissipation factor tgδ that is a function of frequency and carbon black concentration were investigated by AC impedance spectroscopy. The percolation threshold of 5wt% carbon black concentration was obtained from the experimental result of volume resistivity for the conductive composites. It was found that the variation of AC electrical properties, which is a function of frequency, was dramatic and dependent on the filler concentration. It was also found that dependence of the real and the imaginary parts of impendence on frequency decreased with the increased concentration of carbon black, while the phase angle, dielectric constant and dissipation factor increased. The AC electrical properties were given based on the conductive network model and the corresponding equivalent circuit were concluded
Authors: A.M.G. Pinto, A.G. Magalhães, F. Gomes da Silva, A.P.M. Baptista
Abstract: The mechanical behaviour of single lap adhesive joints was characterized, using two commercial acrylic adhesives. For this purpose the surfaces were cleaned and abraded using fine grit abrasives. The effect of temperature and moisture in the mechanical strength was, also, evaluated. For this characterization, mechanical tests were carried out according procedure and geometry foreseen by ASTM D3163-01 [1] and ASTM D4501-01 [2] standards. The results show that it is possible to get good strengths without great surface preparation. The temperature and moisture effect observed don’t seem to be relevant for the mechanical behaviour.
Authors: Jing Tao Yang, Lei Wang, Zheng Yuan Huo, Jie Feng, Feng Chen, Ming Qiang Zhong
Abstract: A super-hydrophobic surface on the polypropylene matrix was fabricated via micromolding and photograft polymerization. A micro-convex body structure was molded by etching templates. The water contact angle could be increased to 138°. The fluoro methacrylate monomers were further grafted to the surface through UV-induced photograft polymerization. The morphology characterization and the spectroanalysis indicated that the rough hierarchical structure (confirmed by scanning electron microscope) and the grafted fluoropolymers (measured by fourier transform infrared spectrum and X-ray energy dispersive spectrometer) made a critical difference. A water contact angle of 160° was arrived.
Authors: Xing Luo, Min He, Jian Bing Guo, Kai Zhou Zhang, Bin Wu
Abstract: An efficiently brominated flame retardant which composed of decabromodiphenyl oxide (DB) and antimonous oxide (AO) was used to flame retardant for long glass fiber reinforced polypropylene (LGFPP). In order to investigate the thermal stability, flame retardancy and mechanical property of DB-AO/LGFPP composites used by thermogravimetric analysis (TGA), limiting oxygen index (LOI), vertical burning (UL-94) and mechanical property tests. The results showed that brominated flame retardant improved flame retardancy of LGFPP efficiently can be proved by TGA, and had less affected on mechanical properties.
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