, and increase the mechanical and physical properties of polypropylene (PP)/wood–fiber composites. The study showed that adding maleated PP (MA-PP) can significantly improves the bio-fiber or flour/matrix bonding [ 16 – 19 ]. Qiu et al . [ 20 ] reported
Authors:M. J. Galante, L. Mandelkern, R. G. Alamo, A. Lehtinen, and R. Paukker
The crystallization kinetics from the melt of metallocene type isotactic poly(propylenes) having the same chain defect concentration and molecular weights ranging from 68480 to 288430 have been studied by differential scanning calorimetry. The crystallization rates and the variation of the rates with crystallization temperature follow a pattern that is basically independent of molecular weight. This result contrasts with the molecular weight dependence on the crystallization rate observed in linear polyethylene, random ethylene copolymers as well as other semicrystalline systems.
Authors:J. Suñol, J. Saurina, R. Berlanga, D. Herreros, P. Pagès, and F. Carrasco
A crystallization kinetics analysis of several polypropylene-polyethylene (PP-PE), PP-rich copolymers was made by means of
differential scanning calorimetry. The crystallization was studied via calorimetric measurements at different cooling rates.
Several additives were added to the base material. Some test samples were subjected to artificial ageing processes. A modified
isoconversional method was used to describe the crystallization process under non-isothermal conditions. The value of the
Avrami parameter was determined for primary and secondary crystallization.
Authors:Nan Zhang, Qin Zhang, Ke Wang, Hua Deng, and Qiang Fu
As one of the most important semicrystalline polymers, isotactic polypropylene (iPP) has been widely studied for its polymorphic characteristic (monoclinic α-modification, trigonal β-modification, orthorhombic γ
This work is dealing with grafting of poly-propylene fibres /POP/ prepared by the pre-irradiation technique. A hydrophility change in irradited and modified samples was studied. Irradiation was performed in a chamber type RCH-gamma-30 radiation equipment, containing60Co. In the radiation modified samples of POP fibres prepared by the preirradiation technique the humidity adsorption increased from 0.1% to 0.56% after the radiation dose of 24.5 kGy has been used. The sorption properties of the samples were studied on McBeen balances with regard to temperature and water-vapour pressure.
Authors:Elaine Gomes, Leila Visconte, and Elen Pacheco
Vermiculite clay (VMT) was organically modified with a quaternary organic salt and added to polypropylene (PP). The compounds
were prepared by melt intercalation using a twin extruder. The morphology of the composites was investigated through wide-angle
X-ray diffraction (WAXD). The WAXD results suggested that exfoliation phenomena were found for the composites with modified
clay. The thermal properties of the obtained composites were studied by means differential scanning calorimetry (DSC) and
thermogravimetry (TG) measurements. A variation in the crystallinity of PP was found. A significant increase of the thermal
stability of PP was achieved in the presence of the modified VMT.
In the case of isotactic polypropylene (PP) as the matrix, the transcrystalline morphology is potentially complex because of the polymorphic nature of this polymer. Depending on the polymerization procedure, thermal history and use of different
Authors:Gy. Marosi, R. Lágner, Gy. Bertalan, P. Anna, and A. Tohl
Interfacial structure plays an important role in the performance of polypropylene composites. Transcrystalline interfacial layer were determined in talc filled polypropylene. The crystallization and melting behaviour of talc and CaCC3 filled polypropylene could be modified with smaller amount of additives like elastomer and surfactants. Through the effect of these additives the structure of interface and the degree of crystallinity could be controlled in filled polypropylene.
Authors:Gy. Marosi, P. Anna, I. Balogh, Gy. Bertalan, A. Tohl, and M. A. Maatoug
Engineering application of polypropylene requires the employment of flame retardants. Reactive compounding of ammonium-polyphosphate and synergist additives with polypropylene is an effective way for forming flame retardant polypropylene. Both the ammonium-polyphosphate and the additives used for improving its performance effect the crystallization and melting behavior of polypropylene. Encapsulation of flame retardant additives with appropriate elastomer, in order to improve their water resistancy, causes further changes in degree of crystallinity and consequently in the mechanical properties.
The modification of polypropylene fibres (POP) and POP fleece prepared by preirradiation technique is discussed. Grafting measure, hydrophility change and dyeing ability of the radiation modified samples were studied. The preirradiation and the simultaneous one were performed in a chamber type RCH-gamma-30 radiation equipment, having the emitters charge of60Co. For radiation-induced grafting 5–30% acrylic acid solution was used. It was proved that the percentage of irradiation-induced grafting of both POP fibres and POP fleece increased with an increase in the radiation dose and the concentration of acrylic acid. Samples modified by this technique have a good dyeing ability and their dyeing intensity increased parallel with the percentage of grafting.