Muhammad Pervaiz

Carbon storage potential in natural fiber composites

Abstract The environmental performance of hemp based natural fiber mat thermoplastic (NMT) has been evaluated in this study by quantifying carbon storage potential and CO2 emissions and comparing the results with commercially available glass fiber composites. Non-woven mats of hemp fiber and polypropylene matrix were used to make NMT samples by film-stacking method without using any binder aid. The results showed that hemp based NMT have compatible or even better strength properties as compared to conventional flax based thermoplastics. A value of 63 MPa for flexural strength is achieved at 64% fiber content by weight. Similarly, impact energy values (84–154 J/m) are also promising. The carbon sequestration and storage by hemp crop through photosynthesis is estimated by quantifying dry biomass of fibers based on one metric ton of NMT. A value of 325 kg carbon per metric ton of hemp based composite is estimated which can be stored by the product during its useful life. An extra 22% carbon storage can be achieved by increasing the compression ratio by 13% while maintaining same flexural strength. Further, net carbon sequestration by industrial hemp crop is estimated as 0.67 ton/h/year, which is compatible to all USA urban trees and very close to naturally, regenerated forests. A comparative life cycle analysis focused on non-renewable energy consumption of natural and glass fiber composites shows that a net saving of 50 000 MJ (∼3 ton CO2 emissions) per ton of thermoplastic can be achieved by replacing 30% glass fiber reinforcement with 65% hemp fiber. It is further estimated that 3.07 million ton CO2 emissions (4.3% of total USA industrial emissions) and 1.19 million m3 crude oil (1.0% of total Canadian oil consumption) can be saved by substituting 50% fiber glass plastics with natural fiber composites in North American auto applications. However, to compete with glass fiber effectively, further research is needed to improve natural fiber processing, interfacial bonding and control moisture sensitivity in longer run.

Mechanical, morphological and structural properties of cellulose nanofibers reinforced epoxy composites

Present study, deals about isolation and characterization of cellulose nanofibers (CNFs) from the Northern Bleached Softwood Kraft (NBSK) pulp, fabrication by hand lay-up technique and characterization of fabricated epoxy nanocomposites at different filler loadings (0.5%, 0.75%, 1% by wt.). The effect of CNFs loading on mechanical (tensile, impact and flexural), morphological (scanning electron microscope and transmission electron microscope) and structural (XRD and FTIR) properties of epoxy composites were investigated. FTIR analysis confirms the introduction of CNFs into the epoxy matrix while no considerable change in the crystallinity and diffraction peaks of epoxy composites were observed by the XRD patterns. Additions of CNFs considerably enhance the mechanical properties of epoxy composites but a remarkable improvement is observed for 0.75% CNFs as compared to the rest epoxy nanocomposites. In addition, the electron micrographs revealed the perfect distribution and dispersion of CNFs in the epoxy matrix for the 0.75% CNFs/epoxy nanocomposites, while the existence of voids and agglomerations were observed beyond 0.75% CNFs filler loadings. Overall results analysis clearly revealed that the 0.75% CNFs filler loading is best and effective with respect to rest to enhance the mechanical and structural properties of the epoxy composites.

Evaluation of the Influence of Fibre Length and Concentration on Mechanical Performance of Hemp Fibre Reinforced Polypropylene Composite

Abstract The paper deals widi die evaluation of interfacial shear stress (ISS) between reinforcement fibre (hemp) and polypropylene matrix through single fibre pull-out method and subsequently the critical length of the composite grade hemp fibre has been determined. In the present study the average ISS value of 5.9 MPa was used to determine the critical length of hemp fibre, which was found to be 3.4 mm. The theoretical prediction of the tensilestrength and modulus of hemp-polypropylene composite by using Kelly-Tyson and Cox-Krenchel models, respectively, have been reported in the paper. Model results were validated by experimental works with different fibre lengths and volume fraction of hemp fibre in the composite. The effect of fibre length and content on the flexural strength and stiffness of the hemp-polypropylene composite has also been studied. The effect of moisture absorption on composite tensile strength was predicted by modifying the Kelly-Tyson model. The model curve was also compared with another set of experimental works done at differentmoisture contents in the composite.

Cellulose-Enabled Polylactic Acid (PLA) Nanocomposites: Recent Developments and Emerging Trends

Environmental consciousness, technology improvement, and stringent regulations have significantly increased the interest of biodegradable polymers in the industry in the past decade and polylactic acid (PLA) represents one of the most promising biopolymers. However, compared to the conventional petroleum-based polymers, owing to its inherent chemistry, PLA has relatively poor mechanical and thermal properties. To broaden its application, it becomes necessary to introduce inorganic/organic fillers into the biopolymer to meet the performance requirements and facilitate the processing. The use of nanoscale fillers is the strategy by exploiting the nature and properties of the nanoparticulates, such as huge surface area per mass, high aspect ratios, and low percolation threshold. Different inorganic particulates (e.g., nanoclay, nanosilica, carbon nanotubes, etc.) have been extensively studied. However, these added nanoparticulates are inorganic and pose considerable health risks from the manufacturing process to their final disposal. In contrast, nanocellulose, produced from renewable resources, has attracted great interest in recent years due to their sustainability and natural abundance. The combination of PLA and nanocelluloses results in a novel class of fully biorenewable resource-based composites. The recent developments and future trends (i.e., processing methods, various properties, and potential applications) of this novel nanocomposite have been discussed in this chapter.

Green Composite Manufacturing via Compression Molding and Thermoforming

Increasing concern over material usage and its impact on the environmental have escalated the growth of green composite materials. There are tremendous opportunities where conventional mineral and synthetic-based materials can be replaced with green composite materials. Before green composites can be used to manufacture various products, it is important to understand their processing steps and optimize process parameters. Past researches on green composites were focused mostly on characterization, and less research can be found in manufacturing of green composites. Common technologies include but are not limited to injection molding, extrusion, thermoforming, and compression molding. In this chapter, manufacturing process of green composites via compression molding and thermoforming is developed based on patents and literature review. Main emphasis is given toward key processing steps, such as material selection, preprocessing, semifinished product manufacturing, and green composite fabrication. Moreover, processing data of some commercially available green composites and biopolymers is summarized.