Search results for "Composite"
showing 10 items of 4584 documents
“Effect of Filler Type and Processing Apparatus on the Properties of the Recycled “Light Fraction” from Municipal Post-Consumer Plastics”
2001
Plastic waste or scraps are generated from two main sources: industrial wastes and post-consumer wastes. By using the flotation method, generally two fractions are obtained from municipal post-consumer wastes: a light fraction, floating on water, and a heavy fraction. The former is essentially made of low and high density polyethylene—LDPE, HDPE—and polypropylene—PP; the heavy fraction is formed by poly(vinyl chloride)—PVC—and poly(ethylene terephthalate)—PET. In this work, the recycling of a light fraction from municipal post-consumer plastics has been studied, considering also the effect of filler type—glass fibres, calcium carbonate and wood fibres—and processing apparatus—discountinous …
Antimicrobial thermoplastic materials for biomedical applications prepared by melt processing
2014
In this work thermoplastic polymers with antimicrobial properties were prepared by incorporating an antibiotic, i.e., ciprofloxacin (CFX), by melt processing. Two different polymers were used as matrices, i.e., polypropylene (PP) and poly(lactid acid) (PLA) and different concentrations of CFX have been incorporated. The antimicrobial properties, the release kinetic and the mechanical performances of the prepared materials were evaluated.
Effect of the processing on the properties of biopolymer based composites filled with wood flour
2008
Wood-polymer composites (WPCs) are well known today in the field of industrial applications, because of several advantages they can grant if compared with mineral filler-polymer composites. These advantages regard the low cost of wood based fillers, the reduced specific weight, the lower hazards for production workers in case of inhalation, the special aesthetic features, environmental issues. The scientific literature reports studies regarding polymer matrices like, for instance, polyethylene and polypropylene, in combination with several natural-organic fillers. However, a limit of these composites is represented by the fact that there is not a full biodegradability: this, in fact, regard…
Effectiveness of organoclays as compatibilizers for multiphase polymer blends - A sustainable route for the mechanical recycling of co-mingled plasti…
2014
We prepare and characterize multiphase systems in which small amounts of recycled polymer, namely polyethylene terephtalate (PET) ground from waste bottles, are dispersed in a co-continuous blend of high-density polyethylene (HDPE) and polypropylene (PP). Some of such ternary systems are also filled with plate-like clay nanoparticles with different polarities, in order to assess their influence on the morphology and mechanical behaviour of the blends. On the basis of preliminary wettability considerations and inspections by means of scanning electron microscopy (SEM), the PET is found to preferentially locate within the PP phase. Such a positioning is desirable in order to minimize the pres…
Polymer Solidification under Pressure and High Cooling Rates
2000
Abstract Polymer solidification under processing conditions is a complex phenomenon in which the kinetics of flow, high thermal gradients and high pressures determine the product morphology. The study of polymer structure formed under pressure has been mainly made using conventional techniques such as dilatometry and differential scanning calorimetry under isothermal conditions or non isothermal conditions but at cooling rates several orders of magnitude lower than those experienced in industrial processes. A new equipment has been recently developed and improved to study the crystallization of polypropylene when subjected to pressure and cooled rapidly. An experimental apparatus essentiall…
Thermomechanical degradation of filled polypropylene
2003
The main problem in post-consumer plastics recycling is due to the thermomechanical stress acting on the melt during the reprocessing operations. The macromolecules break because of the temperature and of the mechanical stress. The extent of degradation is then correlated to the level of mechanical stress which, in turn, is proportional to the viscosity of the melt. The presence of fillers increases the viscosity of the polymers and then it is expected that the level of thermomechanical degradation of these systems is larger than that of the unfilled material. In this work the thermomechanical degradation kinetic of a polypropylene sample is investigated as a function of the calcium carbona…
Properties of PP/MWCNT-COOH /PP composites made by melt mixing versus solution cast /melt mixing methods
2015
An approach on improvement of the properties of polypropylene / carbon nanotube (PP/CNT) composites is reported. PP blend compositions with carboxylic acid functionalized multi-walled carbon nanotubes (MWCNT-COOH) at filler content 1.0 wt.% were researched. One part of the composites was manufactured by direct thermoplastic mixing PP with the filler, but the other one was made from solution casted masterbatch with the following thermoplastic mixing. An increase of mechanical properties (Young's modulus, storage modulus and tensile strength), compared to an increase of glass transition temperature indicated a reinforcement effect of CNTs on PP matrix, determined from the tensile tests and di…
Blends of polypropylene and nylon 6: Influence of the compatibilizer, molecular weight, and processing conditions
1993
The aim of this work is to study the influence of different types of compatibilizing agents, different processing conditions, and the molecular weight of the two components on the properties of immiscible blends of polypropylene and nylon 6. Increasing the content of the functional group of the modified polypropylene and the content of nylon in the blend, the effectiveness of the compatibilization improves. The same effect is observed by decreasing the molecular weight of the two components, in particular, that of the polyamide. The influence of the processing conditions is slight provided no degradation takes place during processing. © 1993 John Wiley & Sons, Inc.
Thermomechanical degradation of compatibilized and uncompatibilized nylon 6/polypropylene blends
1999
The thermomechanical degradation of compatibilized and uncompatibilized nylon 6/polypropylene blends has been followed to investigate the changes of structure, morphology and properties of these blends as a function of the type of compatibilizer and of the processing time. The degradation of the blends mostly depends on the type of functional group of the polypropylene. Indeed, the thermolability of an acrylic acid-functionalized polypropylene gives rise to a continuous decrease of the compatibilization efficiency and the properties of the blend with this polypropylene sample much worse than that observed for the blend with a maleic anhydride-functionalized polypropylene.
Multifunctional polyurethane foams with thermal energy storage/release capability
2020
In this work, polyurethane (PU) insulating panels containing different amounts of a microencapsulated paraffin with a nominal melting temperature of 24 °C, used as phase change material (PCM), were produced. The resulting panels behaved as multifunctional materials able to thermally insulate and simultaneously storing/releasing thermal energy near room temperature. The panels were characterized from a microstructural, thermal and mechanical point of view. Viscosity measurements highlighted an increase in the viscosity values of the PU liquid precursors due to the addition of the capsules, and this could lead to some difficulties during the production stages, especially in the mixing and foa…