Chopped glass and recycled newspaper as reinforcement fibers in injection molded poly(lactic acid) (PLA) composites: A comparative study

Functionalization, compatibilization and properties of polypropylene composites with Hemp fibres

Recycled newspaper cellulose fiber (RNCF) reinforced poly(lactic acid) (PLA) biocomposites were fabricated by a microcompounding and molding system. RNCF-reinforced polypropylene (PP) composites were also processed with a recycled newspaper fiber content of 30 wt % and were compared to PLA/RNCF composites. The mechanical and thermal−mechanical properties of these composites have been studied and compared to PLA/talc and PP/talc composites. These composites possess similar mechanical properties to talc-filled composites as a result of reinforcement by RNCF. The tensile and flexural modulus of the biocomposites was significantly higher when compared with the virgin resin. The tensile modulus (6.3 GPa) of the PLA/RNCF composite (30 wt % fiber content) was comparable to that of traditional (i.e. polypropylene/talc) composites. The DMA storage modulus and the loss modulus of the RNCF−PLA composites were found to increase, whereas the mechanical loss factor (tan δ) was found to decrease. Differential scanning c...

A Study on Biocomposites from Recycled Newspaper Fiber and Poly(lactic acid)

Summary: Functionalized MWNTs were incorporated into PU by solution mixing to improve the mechanical and thermal properties of composites. A homogeneous dispersion of MWNTs was successfully achieved in PU matrix as evidenced by scanning electron microscopy. It may be attributed to the hydrogen bonds existing between CO groups of hard segments of PU chains and COOH groups of the MWNT-COOH. The incorporation of the MWNTs effectively enhanced the crystallization of the PU matrix through heterogeneous nucleation, and the nucleation effect was more evident at 10 wt.-% functionalized MWNTs as compared to other composite systems. Mechanical properties of the PU-MWNTs composites were assessed as a function of MWNT concentration and dispersion of MWNT in PU matrix. The most significant improvement in mechanical properties was obtained, e.g., 740% increase in modulus and 180% increase in tensile strength over pure PU with 20% MWNT content. The thermal stability of composites due to thermal gravimetric measurements was significantly improved.

A possible interaction of H-bonding existed between PU chain and MWNT-COOH.

Effect of Functionalized Carbon Nanotubes on Molecular Interaction and Properties of Polyurethane Composites

Publisher Summary The use of natural fibres in composite materials is increasing due to legislation forcing automotive manufacturers to reuse and recycle materials, which is leading to an increase in the bio-based material content in automotive applications. Natural fibres being eco-friendly, lightweight, strong and low cost have already started to replace glass and mineral fillers in numerous engineering applications in automobiles, furniture, packaging and construction. The automobile industry has discovered the advantages to be gained from natural fibres and the Natural-Fibre Composites (NFC) made through the combination of natural fibres with different polymers such as: Polypropylene (PP), Polyethylene (PE), and Polyvinylchloride (PVC). A potentially large area of usage of these composites is the automotive industry because the need is greatest. Fibre-reinforced composites have gained importance in the automotive sector where high mechanical properties and dimensional stability must be coupled with low weight. However, the use of natural fibres also has some limitations. They are moisture sensitive and their bonding with polymer matrices is weak. Moreover, there are some concerns over natural-fibre quality, consistency and processing temperature limits.

Natural-fiber composites in the automotive sector

Application of different macrokinetic models to the isothermal crystallization of PP/talc blends

Abstract The non-isothermal behaviour of crystallization of polypropylene (PP) and its talc-filled composites was investigated by means of differential scanning calorimetry. Different analytical methods were used to describe the crystallization process. According to the behaviour of crystallization temperature, crystallization activation energy and crystallization parameters and coefficient, talc results in an increase in PP crystallization rate and in a decrease in total energy opposing to homogeneous crystallization. Velisaris-Seferis’ kinetic equation was found to describe reasonably well the non-isothermal behaviour of crystallization of PP and its filled composites.

Carmen Ustariz

Papers

Application of different macrokinetic models to the isothermal crystallization of PP/talc blends

Characteristics of non-isothermal crystallization of polypropylene with and without talc