Mechanical and water absorption behaviors of corn stalk/sisal fiber-reinforced hybrid composites

Fabrication of high performance poly(vinyl alcohol)/straw composite film used for package via melt casting and biaxial stretching

A high performance poly(vinyl alcohol)/straw (PVA/SP) composite film for package was fabricated in this study by using thermal processing technology of PVA established in our research group and biaxial stretching technology. The introduction of SP disrupted the original hydrogen bonds in modified PVA by forming new hydrogen bonds with the hydroxyl groups of each component in modified system, thus promoting the stable melt casting of PVA/SP composites and also endowing the obtained PVA/SP precursor sheets with good drawability. Upon biaxial stretching, SP reinforced the crystalline structure and orientation of PVA through their hydrogen bonds with PVA, improving the mechanical strength, crystallinity and thermal stability of PVA/SP films. The film with 3.0 × 3.0 stretching ratios demonstrated the exceptional tensile strength (62.2 MPa), tear strength (119.7 kN/m), low heat shrinkage (5.2 %), and oxygen permeability coefficient (1.38 × 10-16 cm3·cm/cm2·s·Pa), which surpassed most conventional plastic films used in food packaging field. This research not only pioneered an environmentally friendly packaging solution, but also offered a novel strategy for solid-state high-value, large-scale and economical utilization of waste crop straw, greatly avoiding the adverse effects of its burning on the environment.

Effect of lignocellulosic corn stalk on mechanical, physical, and thermal properties of injection moulded low density polyethylene composites: An approach towards a circular economy

Escalating concern over global warming, which is mostly associated with deforestation, has led to the development of new classes of materials that can replace wood and better utilise natural resources. Presently, waste is a significant factor in recycling. In this regard, one of the leading contributors to waste is agricultural waste, which includes dried branches, leaves of trees, plants, and other organic materials. In the current study, waste from corn agriculture was utilised as a potential reinforcement for the fabrication of corn stalk-low density polyethylene (CS-LDPE) composites via an injection moulding technique at 170 °C. The different parameters were assessed to develop composites using CS, including physico-chemical, macromolecular, mineralogical, elemental, and morphological analysis. The amount of corn stalk (CS) was varied from 10 to 50 wt% with respect to the polymer. The mechanical, physical and thermal performance of the composites was examined. The density and water absorption of the composites were found to remain within the ranges of 1.00-1.11 g/cm3 and 0.22-1.01 %, respectively, whereas these parameters increased as the proportion of CS increased. The thermal conductivity decreases with the addition of CS from 0.36964 ± 0.020 to 0.22388 ± 0.002 W/mK. It was observed that adding CS to the composites increased their tensile and flexural properties, but decreased their impact strength. The maximum flexural strength of 14.40 ± 1.558 MPa, flexural modulus of 752.53 ± 180.409 MPa, tensile strength of 10.49 ± 0.946 MPa and tensile modulus of 539.79 ± 91.044 MPa were observed with a 50 % CS content. The results suggest that these materials have considerable potential to serve as a cost-effective substitute for the conventional lignocellulosic fillers in the manufacturing of wood-plastic composites.

Experimental investigation of properties and aging behavior of pineapple and sisal leaf hybrid fiber-reinforced polymer composites

Using plant leaf fibers as reinforcements in thermo-plastic resins to produce affordable and lightweight composites is the subject of growing interest in research. Although these fibers have several advantages over synthetic fibers, mechanical characteristics of composites such as moisture absorption, poor wettability, and insufficient adhesion between the matrix and the fiber cause disadvantages. To overcome these issues, in this experimental study, two leaf-based plant fibers are hybridized and the composites have been fabricated by hand lay-up process. The composites were subjected to several tests. The results showed that the hybridization of sisal and pineapple leaf fiber (PALF) increases the mechanical strength of the composite by a maximum tensile strength of 3.59 kN, a little lower flexural strength than the individual fiber, and a noticeably higher compressive strength. The results further showed that the decreased affinities for moisture content and the aged composites seem to be prone to be hydrophilic. Findings of the experiments reveal that the hybridization of sisal and PALF has a significant influence on the properties of the composites. The scanning electron microscopy micrographs of fractured surfaces have been examined, and the findings have effectively been investigated.

Preparation, Characterization and Tailoring Properties of Poly(Vinyl Chloride) Composites with the Addition of Functional Halloysite-Lignin Hybrid Materials

In this article, halloysite-lignin hybrid materials (HL) were designed and obtained. The weak hydrogen bonds found between the components were determined based on Fourier transform infrared spectroscopy (FTIR), proving the achievement of class I hybrid systems. The HL systems were characterized by very good thermal stability and relatively good homogeneity, which increased as the proportion of the inorganic part increased. This was confirmed by analyzing scanning electron microscope (SEM) images and assessing particle size distributions and polydispersity indexes. Processing rigid poly(vinyl chloride) (PVC) with HL systems with a content of up to 10 wt% in a Brabender torque rheometer allowed us to obtain composites with a relatively homogeneous structure confirmed by SEM observations; simultaneously, a reduction in the fusion time was noted. An improvement in PVC thermal stability of approximately 40 °C for composites with HL with a ratio of 1:5 wt/wt was noted. Regardless of the concentration of the HL system, PVC composites exhibited inconsiderably higher Young's modulus, but the incorporation of 2.5 wt% of fillers increased Charpy impact strength by 5-8 kJ/m² and doubled elongation at break. This study demonstrated that favorable mechanical properties of PVC composites can be achieved, especially with an HL system with a ratio of 5:1 wt/wt.

Enhanced Mechanical Properties of Polyvinyl Chloride-Based Wood–Plastic Composites With Pretreated Corn Stalk

Wood–plastic composites (WPCs) are a type of environmentally friendly materials widely used in daily life. This paper selected low-value biomass, corn stalk (CS), as the lignocellulosic resource for polyvinyl chloride (PVC)-based WPCs. To depict the relationship between lignocellulosic composition (cellulose, hemicellulose, and lignin) and mechanical performance of WPCs, pretreatments have been optimized to selective removal of lignin using an alkaline-EtOH stewing process and selective removal of hemicellulose using an acid stewing process. The αC sample, in which both lignin and hemicellulose were removed, shows the highest degree of crystallinity (72.60%) as estimated from X-ray diffraction analysis results and fibrous morphology with the highest aspect ratio as seen in scanning electron microscopy images. Compared with PVC/CS, PVC/αC gives a substantial increase in tensile strength and modulus by 37.21 and 21.66% and flexural strength and modulus by 29.98 and 34.88%, respectively. These improvements lie in the reinforcing effect of a fibrous structure and the improved interfacial compatibility as proven by scanning electron microscopy and dynamic mechanical analyzer results. Considering the extracted lignin and hemicellulose can be further developed to valuable biochemicals, the pretreatment to CS adds value to both WPC materials and biorefinery products.

Research on the surface morphological and electrochemical modification of polyvinyl chloride induced by KrF and ArF excimer laser direct writing

To obtain superior performance in adhesion, polyvinyl chloride (PVC) substrates were modified by excimer laser direct writing with different operating wavelengths, scanning speeds, and laser fluences. The induced morphological and electrochemical changes were detailedly tested and analyzed. Microchannels were formed on the surfaces of the PVC substrates due to the laser ablation, where the melted-resolidified droplet-like structures were distributed uniformly and can significantly improve the mechanical interlock. Furthermore, according to the Fourier transform infrared spectroscopy and x-ray photoelectron spectroscopy analyses, Lewis bases such as hydroxyl and carbonyl were formed after laser treatment, which is beneficial to the adhesion strength. These mechanical and chemical modifications may play positive roles in enhancing the bonding strength of the PVC edge bandings.

Mechanical and Thermal Characterization of Natural Intralaminar Hybrid Composites Based on Sisal

The main objective of this work was to investigate the effect of hybridization on the mechanical and thermal properties of intralaminar natural fiber-reinforced hybrid composites based on sisal. Ramie, sisal and curauá fibers were selected as natural fiber reinforcements for the epoxy matrix based composites, which were produced by the hand lay-up technique. Tensile, flexural and impact tests were carried out according to American society for testing and materials (ASTM) standards to characterize the hybrid composites, while differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to evaluate the thermal properties. It was found that the mechanical properties are improved by hybridization of sisal based composites. The thermal analysis showed that the hybridization did not significantly affect the thermal stability of the composites. A scanning electron microscopy (SEM) was used to examine the fracture surface of the tested specimens. The SEM images showed a brittle fracture of the matrix and fiber breakage near the matrix.