Highly Filled Polypropylene Rubber Wood Flour Composites

In this research, polypropylene composites filled with Hevea Brasilliensis wood flour at filler content up to 60 wt% were prepared and investigated in order to determine the effects of polymer melt flow rate (MFR), number of reprocessing times, filler size, and filler content on thermal and mechanical properties. The results reveal that the composites of polypropylene with higher melt flow rate (lower viscosity) provided greater values of flexural and tensile properties. The study additionally exhibits the recyclability potential without losing mechanical properties. Furthermore, both flexural and tensile modulus increased, while both flexural and tensile strength decreased with increasing wood flour contents. In addition, the average particle size of wood flour that was suitable for improving the mechanical properties was approximately 200-300 μm. In the last section of the research, the effects of maleic anhydride grafted polypropylene (MAPP) coupling agent were investigated. It is worth noting that, the flexural strength and tensile strength of highly filled composites with MAPP at 5 wt% (based on wood flour) were approximately 110% and 87% higher than those of the composites without MAPP, respectively. In the presence of coupling agent, the enhancement of interfacial adhesion was analyzed using scanning electron microscope (SEM)

Thermomechanical and Rheological Behaviours of Waste Glass Fibre-Filled Polypropylene Composites

The composites between the reinforced glass fibre wastes obtained from surfboard manufacturing industry and polypropylene were developed for value adding and environmental reasons. The thermomechanical and rheological behaviours of the composites were investigated. Glass fibre contents were varied from 5 to 30 wt%. The effects of maleic anhydride grafted polypropylene (MA-PP) compatibilizer on the behaviours were also determined. The results revealed that the addition of glass fibre was able to reduce the heat of fusion of the composite. Additionally, the tensile and flexural properties were increased with increasing the glass fibre contents following the rule of mixtures. The addition of MA-PP led to enhance tensile and flexural properties due to the improvement of the adhesion between matrix and glass fibre, which is correlated with morphological observations. From the rheological studies, the apparent flow activation energy revealed that the addition of glass fibre decreased the fluidity of the molten composite materials; however, it could be slightly improved by using MA-PP

Rheological and Thermomechanical Characterizations of Fumed Silica-Filled Polybenzoxazine Nanocomposites

The composites of fumed silica-filled polybenzoxazine at various nanofiller contents ranging from 0 to 10 wt% were fabricated. In this study, the rheological and thermomechanical analysis of neat polybenzoxazine and its nanocomposites were performed. The rheograms show the shear thinning behaviours of the melted nanocomposite compound. In addition, the complex viscosity of the nanocomposites revealed that the liquefying temperature of these molding compounds increased with increasing the amount of fumed silica, while the gel-point temperature was not changed even though the amount of nanofiller was increased. The DSC thermograms confirmed that fumed silica loading had neither retarding nor accelerating effect on the thermal curing reaction of the benzoxazine monomer. Furthermore, the flexural modulus and microhardness of the nanocomposites were increased with an increase of the nanofiller. DMA thermograms also revealed that the glass transition temperatures (Tg) of pure polybenzoxazine were shifted from 157oC to higher values from the presence of the fumed silica

Comparison of Gamma Radiation Crosslinking and Chemical Crosslinking on Properties of Methylcellulose Hydrogel

In this research, characteristics of methylcellulose (MC) films modified with two crosslinking methods were investigated. The first method was the use of a glutaraldehyde (GA) crosslinker to promote hemi-acetal linkages between MC chains. The second one was gamma irradiation to form insoluble MC gel by intermolecular crosslinking. The effects of the MC concentration on the degree of crosslinking, water absorption, gel content, degree of swelling, and thermomechanical properties were determined. The results indicate that the chemically crosslinked MC films show lower polarity than the radiation crosslinked films. The nature of the crosslinkings was also revealed with FTIR spectra. The water-swelled films of chemically crosslinked MC were found to provide homogeneous gel structure whereas the radiation crosslinked MC films were observed to render less uniform crosslinked films

KevlarTM Fiber-Reinforced Polybenzoxazine Alloys for Ballistic Impact Application

A light weight ballistic composites from KevlarTM-reinforcing fiber having polybenzoxazine (BA)/urethane prepolymer (PU) alloys as a matrix were investigated in this work. The effect of alloy compositions on the ballistic composite properties was determined. The results revealed that the enhancement in the glass transition temperature (Tg) of the KevlarTM-reinforced BA/PU composites compared to that of the KevlarTM-reinforced polybenzoxazine composite was observed. The increase of the elastomeric PU content in the BA/PU alloy resulted in samples with tougher characteristics. The storage modulus of the KevlarTM-reinforced BA/PU composites increased with increasing the mass fraction of polybenzoxazine. A ballistic impact test was also performed on the KevlarTM-reinforced BA/PU composites using a 9 mm handgun. It was found that the optimal contents of PU in the BA/PU alloys should be approximately 20wt%. The extent of the delaminated area and interfacial fracture were observed to change with the varied compositions of the matrix alloys. The appropriate thickness of KevlarTM-reinforced 80/20 BA/PU composite panel was 30 plies and 50 plies to resist the penetration from the ballistic impact equivalent to levels II-A and III-A of NIJ standard. The arrangement of composite panels with the higher stiffness panel at the front side also showed the best efficiency of ballistic penetration resistance

Development of NIR light-responsive shape memory composites based on bio-benzoxazine/bio-urethane copolymers reinforced with graphene

In this work, shape memory polymers (SMPs) were developed from a combination of a bio-based benzoxazine (BZ) monomer and polyurethane prepolymer (PU-prepolymer), both derived from bio-based raw materials. The bio-based BZ monomer (V-fa monomer) was synthesized through a Mannich condensation reaction using vanillin, paraformaldehyde, and furfurylamine. The bio-based PU-prepolymer was obtained by reacting palm oil polyol (MW = 1400 Da) and toluene diisocyanate (TDI). To investigate the curing behavior of poly(V-fa/urethane), with a mass ratio of 50/50, differential scanning calorimetry was employed. The structure of the resulting poly(V-fa/urethane) was confirmed using Fourier transform infrared spectroscopy. Furthermore, the synthesized V-fa/urethane copolymers with weight ratios of 70/30, 60/40, 50/50 and 40/60 were observed to exhibit shape memory behaviors induced by near-infrared irradiation (808 nm). Poly(V-fa/urethane), specifically with a mass ratio of 50/50, demonstrated superior shape memory performance. It exhibited a remarkable capacity to retain the temporary shape up to 90%, achieve 99% shape recovery, and exhibit a recovery time of 25 s. The shape memory properties were further improved with the addition of 3 wt% graphene nanoplatelets (GNPs), exhibiting an improvement in the shape fixity value to 94%, and shape recovery time value to 16 s. Moreover, our findings suggest that 60/40 poly(V-fa/urethane) reinforced with 3 wt% GNPs possesses favorable characteristics for applications as multiple SMPs, with shape fixity values of 97% and 94%, and shape recovery values of 96% and 89% for the first and second shapes, respectively. Graphical abstract: Development of NIR light-responsive shape memory composites based on bio-benzoxazine/bio-urethane copolymers reinforced with graphen

Effects of Alkyl-Substituted Polybenzoxazines on Tribological Properties of Non-Asbestos Composite Friction Materials

A series of substituted polybenzoxazines was synthesized and studied as binders in non-asbestos friction composite materials. The structures of the polybenzoxazines were varied in a systemic fashion by increasing the number and position of pendant alkyl (methyl) groups and was accomplished using the respective aromatic amines during the polymer synthesis step. By investigating the key thermomechanical and tribological characteristics displayed by the composite materials, the underlying structure-properties relationships were deconvoluted. Composite friction materials with higher thermomechanical and wear resistance properties were obtained from polybenzoxazines with relatively high crosslink densities. In contrast, polybenzoxazines with relatively low crosslink densities afforded composite friction materials with an improved coefficient of friction values and specific wear rates

Alloys and composites of polybenzoxazines: properties and applications

This book provides an introduction to the unique and fascinating properties of alloys and composites from novel commercialized thermosetting resins based on polybenzoxazines. Their outstanding properties such as processability, thermal, mechanical, electrical properties as well as ballistic impact properties of polybenzoxazine alloys and composites make them attractive for various applications in electronic packaging encapsulation, light weight ballistic armour composites and bipolar plate in fuel cells

Alloys and Composites of PolybenzoxazinesProperties and Applications /

IX, 159 p. 114 illus., 7 illus. in color.online r

Thermomechanical and rheological behaviours of waste glass fibre-filled polypropylene composites

The composites between the reinforced glass fibre wastes obtained from surfboard manufacturing industry and polypropylene were developed for value adding and environmental reasons. The thermomechanical and rheological behaviours of the composites were investigated. Glass fibre contents were varied from 5 to 30wt%. The effects of maleic anhydride grafted polypropylene (MA-PP) compatibilizer on the behaviours were also determined. The results revealed that the addition of glass fibre was able to reduce the heat of fusion of the composite. Additionally, the tensile and flexural properties were increased with increasing the glass fibre contents following the rule of mixtures. The addition of MA-PP led to enhance tensile and flexural properties due to the improvement of the adhesion between matrix and glass fibre, which is correlated with morphological observations. From the rheological studies, the apparent flow activation energy revealed that the addition of glass fibre decreased the fluidity of the molten composite materials; however, it could be slightly improved by using MA-PP