Extruded versus solvent cast blends of poly(vinyl alcohol-co-ethylene) and biopolymers isolated from municipal biowaste

Water-soluble biopolymers (SBO) were isolated from the alkaline hydrolysate of two materials sampled from an urban waste treatment plant; that is, an anaerobic fermentation digestate and a compost. The digestate biopolymers contained more lipophilic and aliphatic C, and less acidic functional groups than the compost biopolymers. The SBO were blended with poly (vinyl alcohol-co-ethylene), hereinafter EVOH. The blends were extruded and characterized by FTIR spectroscopy, size exclusion chromatography (SEC)– multi angle static light scattering (MALS) analysis, and for their thermal, rheological, and mechanical properties. The blends behavior depended on the type of SBO and its relative content. Evidence was obtained for a condensation reaction occurring between the EVOH and SBO. The best results were obtained with the blends containing up to 10% SBO isolated from the biowaste anaerobic digestate. Compared with the neat EVOH, these blends exhibited lower melt viscosity and no significant or great difference in mechanical properties. The results on the extrudates, compared with those previously obtained on the same blends obtained by solvent casting, indicate that the blends properties depend strongly also on the processing technology

Macro and micromechanics analysis of short fiber composites stiffness: The case of old newspaper fibers-polypropylene composites

Stiffness is one of the most relevant characteristics of composite materials. Natural wood fibers have demonstrated their ability to increase the Young's moduli of composite materials, and old newspapers are a potential source of reinforcing fibers for composite materials. There are some micromechanic models to predict the Young's modulus of composite materials, and one of the input data is the intrinsic modulus of their fibers. This intrinsic modulus is a value which is difficult or impossible to measure in the case of wood fibers, due to their measures. This paper evaluates the stiffening abilities of old newspaper fibers and the possibility to back calculate the value of the intrinsic Young's Modulus by means of micromechanic models. Different percentages of old newspaper fibers were compounded with polypropylene (PP). Micromechanics of the fibers were obtained using Hirsch model, Cox-Krenchel's model, Tsai-Pagano model and Halpin-Tsai equations. The most important results were the average intrinsic Young's modulus of the fibers, the mean orientation angle and the mean modulus efficiency factor.Serrano, A.; Espinach, FX.; Tresserras, J.; Rey Tormos, RMD.; Pellicer, N.; Mutje Pujol, P. (2014). Macro and micromechanics analysis of short fiber composites stiffness: The case of old newspaper fibers-polypropylene composites. Materials and Design. 55:319-324. doi:10.1016/j.matdes.2013.10.011S3193245

Review of natural fibre-reinforced hybrid composites

Natural fibre-reinforced hybrid composites which contain one or more types of natural reinforcement are gaining increasing research interest. This paper presents a review of natural fibre-reinforced hybrid composites. Both thermoplastic and thermoset composites reinforced by hybrid/synthetic fibres or hybrid/hybrid fibres are reviewed. The properties of natural fibres, the properties and processing of composites are summarised

Influence of Short Glass Fiber Addition on the Mechanical Properties of Sisal Reinforced Low Density Polyethylene Composites

This paper presents the evaluation of enhancement in the mechanical properties of short sisal fiber reinforced polyethylene composites by the incorporation of short glass fiber as an intimate mix with sisal. Intimately mixed short glass-sisal hybrid fiber reinforced polyethylene composites (GSRP) were prepared by solution mixing technique. The effects of fiber orientation and alkali treatment on sisal fiber in GSRP were studied. Addition of relatively small volume fraction of glass (0.03) to the sisal reinforced polyethylene matrix (SRP) enhances the tensile strength of longitudinally oriented composites by about 80%. Addition of the same volume fraction of glass to the alkali treated sisal incorporated SRP enhances the tensile strength by more than 90%. The flexural strength of the longitudinally oriented composites was also studied. The incorporation of glass fiber ( V f = 0.03) to SRP enhances the flexural strength by more than 60%. The effect of hybridization on water absorption tendency of the sisal fiber was studied by immersing SRP and GSRP in boiling water for 3 hours. It was observed that water uptake of GSRP was 2 to 4 times less than that of SRP composites. Halpin-Tsai equation for composites was tried for calculating the tensile modulus of longitudinally oriented GSRP. </jats:p