Introduction to Composite Materials

Composite materials have played an important role throughout human history, from housing early civilizations to enabling future innovations. Composites offer many benefits; the key among them are corrosion resistance, design flexibility, durability, light weight, and strength. Composites have permeated our everyday lives such as products that are used in constructions, medical applications, oil and gas, transportation, sports, aerospace, and many more. Some applications, such as rocket ships, probably would not get off the ground without composite materials. This chapter addresses the advantages of fibre composite materials as well as fundamental effects, product development, and applications of fibre composites, including material chemistry, designing, manufacturing, properties, and utilisation of the materials in various applications

Natural Fibers for Sustainable Bio-Composites

Over the past decade, the concept of utilizing green materials has become more mainstream. With considerable awareness of preserving the environment, sincere efforts across the globe can be cited in looking for bio-degradable and bio-based sources. Applications of bio-based materials from renewable and bio-degradable sources for preparation of higher valued green chemicals and bio-based products have forced many scientists to investigate the potential use of natural fibers as reinforcement materials for green bio-composites. Cellulosic fibers are becoming very interesting for bio-based material development as they possess advantages with their mechanical properties, low density, environmental benefits, renewability, and economic feasibility. Recently, natural-fiber polymer composites have received much attention for different industrial applications because of their low density and renewability. The bio-composites with natural fiber components are derivatives of depleting resources and can be considered to have substantial environmental and economic benefits. This chapter addresses the potential utilization of natural fiber for the development of green polymer composite materials, with the objective to elucidate the possibility of using these bio-based materials for various industrial applications

Application of Lignins in Formulation and Manufacturing Bio- Based Polyurethanes by 31P NMR Spectroscopy

The application of several industrial and technical biomass lignins from forestry and agricultural residues extracted by different chemical pulping processes in view of bio-based polyurethanes were studied. Several qualitative and quantitative methods were utilized to characterize and elucidate lignin profiles by evaluating their physical and chemical properties as a potential substitute for petroleum-based polyols. The morphology, molecular weight distributions, elemental compositions, glass transition temperature and several important functional groups containing hydroxyl units were classified and their contents were determined quantitatively. In this chapter, lignin substitution in polyurethane by (i) direct substitution, (ii) with combination of polyols or (iii) chemically modified was reviewed. The emerging information aims at addressing a number of pressing issues relevant to the scientific development for value-added applications from lignins during industrial production of biofoams

Targeting Deforestation Through Local Forest Governance in Indonesia and Vietnam

Community-based forest management (CBFM) is recognized as an effective solution to find a balance between forest conservation and livelihood improvement in localities. Both Indonesia and Vietnam initiated CBFM during the 1990s due to similar contexts of rapid deforestation, high rate of poverty, and urgent demand for local participation in forest management. Given the difference in geographical, socioeconomic and sociopolitical settings, the progress of CBFM setting and operation in each country was different. In Indonesia, the government has adopted traditionally favored large-scale, capital-intensive industries that had monopolized the forest economy, resulting in serious ecological and economic problems. This management style has caused serious illegal logging and forest conversion activities that destroyed 70% of country forest areas during last 50 years (Rukmantara, 2006). In Vietnam, the government has managed forests through its state forest enterprises (SFEs) since the country’s reunification in 1975. During the period 1943–1993, Vietnam lost about 5 million hectares of forests, which reduced forest cover from 43% to 27.8% (de Jong et al., 2006). Both countries have adopted centrally managed forest management systems where all decision- making power comes from the state. This system excludes local people from participating in the decision-making process, abandoning them from access to forest rights, and eliminating them from their forest-dependent livelihood practices. Consequently, it has caused serious impacts on ecological and economic issues at global, national, and local levels. This chapter identifies some common elements that influenced local forest governance through CBFM and their implications to ensure the access for the poor to natural resources for improving their livelihoods and guaranteeing the sustainability of the forest ecosystem service

Understanding the effect of adding nanoclays into epoxies

Different preparation methods and formulations of epoxy nanocomposites have been examined. The effects of each parameter, such as different types of clay, different types of curing agent, and processing conditions (temperature, time, speed), on dispersion of the clay particles were evaluated using different means, such as field emission gun scanning electron microscopy (FEGSEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and viscometer. Curing behavior was studied by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Thermal properties of epoxy nanocomposites were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI). Dynamic mechanical properties were studied by dynamic mechanical analysis (DMA). Tensile, flexural, compression, impact, surface hardness and fracture toughness were also examined. A new method to disperse organoclay into epoxy without using solvent, and using high speed mixing (TS), is proposed. The results obtained from this study provide a good understanding of the relationship between the formulation, processing conditions and performance. Significant improvement in stiffness and storage modulus was observed in nanocomposites formulated with better dispersion using TS. However, the extent of the improvement of the nanocomposites' performance depends on the type of the clay and the curing agent. In addition, the processing conditions have great effects on the final properties of epoxy nanocomposites

The acacia plantation boom in Thừa Thiên Huế Province, Central Vietnam: A survey of tree farmers' shifting livelihoods, environmental perceptions, and occupational perspectives

The rise of exotic-species-based plantation forestry in biodiverse tropical countries transforms livelihoods and environmental qualities in various ways. Through 180 structured interviews of different types of acacia plantation owners (producers of woodchips/sawlogs, with/without membership in a recent Forest Stewardship Council [FSC] program) we investigated such transformations in three districts along a lowland-upland gradient in Thừa Thiˆen Huế Province, Central Vietnam. We focused on how trajectories of livelihood and income changes related to the farmers’ perceptions on environmental changes, and how this, in turn, was linked to the farmers’ assessments of opportunities, risks, and concrete plans in tree cultivations. Sawlog producers (especially with FSC-certification) in the lowlands had been among the first to plant acacias in the 1990s, and in 2018 usually owned large plantations. In contrast, most farmers producing just woodchips were smallholders. Before acacias the farmers’ livelihoods were often more diversified in terms of agricultural products. Since then, many farmers (especially in the lowlands) abandoned rice/cassava production and/or livestock keeping to concentrate on wood production, willingly and/or as an outcome of land conversion (enclosure) to privatised plantations. Farmers’ incomes and material assets usually increased (especially FSC-farmers), but most smallholders still depended on incomes from subsidiary wage labor. Within a context of ‘development’ improvements were also seen in infrastructure (buildings, roads, water provisioning) and public services (education, health). Considering acacia planting most farmers (especially FSC-farmers in the lowlands) saw environmental improvements in terms of soil fertility and landscape amenity, but not wildlife habitat. Most farmers also saw plantation value (especially on longer rotations) in terms of natural hazards mitigation (i.e. floods, droughts, soil erosion), but storms were also noted as the main risk to plantations (especially in the uplands). Another emerging risk was posed by plant diseases affecting acacias in the mid-/lowlands. Projective future plans to change plantation areas and/or crop rotations depended on the farmers’ economic strengths in terms of plantation land or other capital. Regarding future risks most farmers noted environmental impacts (storms, plant diseases) rather than economic factors (with wood market prices considered stable). Overall, the results suggest an appreciable value of acacia plantations to farmers, however with some marked distinctions between richer (FSC-certified) and poorer (smallholder) farmers as well as farmers in different regions with distinct terrain and land use management histories. We discuss such distinctions whilst also noting relevant study limitations connected to the complex socio-politics of land titling and uses, especially in the uplands

The Culture of Names – A Comparison between Vietnam and Denmark

This project discusses the topic of personal names and the cultures of different peoples and their particularities, specifically in Vietnam and Denmark. The first part of this paper gives a brief history of naming traditions (mostly relating to Western European traditions). The second part of the paper compares two families of different ancestries (the Trịnhs and the Albertsons) and their naming strategies as they immigrated to the United States. By looking at the names given to each child in the Trịnh family in different generations, it is possible to describe the merging process taking place between the Vietnamese and American cultures. Likewise, with the Albertson family, it is possible to describe their family history by looking at their surnames over the generations as they immigrated to America from Denmark. Materials cited in this research include personal interviews, books on culture and language (in English and Vietnamese), as well as various data records (in English and Danish)

Acacia Plantation Development and the Configuration of Tree Farmers' Agricultural Assets and Land Management—A Survey in Central Vietnam

Since 1990 acacia-based tree plantations have fast expanded in Vietnam, now supporting a multi-billion-dollar export-oriented wood industry which is transforming from woodchip production to value-added products. Within this dynamic context, tree farmer associations have started to produce sawlogs under FSC (Forest Stewardship Council) certification. In this paper, we retrace the development of plantation assets, investigating farmers’ current livelihoods and land management, specifically considering various aspects of sustainability. We interviewed 180 tree farmers in three districts (lowland–upland regions) of Thừa Thiên Huế Province, including sawlog producers with and without FSC and smallholder producers of woodchips. Acacia planting in ‘barren lands’ was initiated through state programs in the 1990s (low-/midlands) and 2010s (uplands). Farmers now producing FSC sawlogs were among the first to gain forestland tenure; they now own large plantations (on good terrain), are in tune with policies and maintain resources/capacities to adopt management in line with FSC standards. Yet, most farmers also retain plots for easy-to-manage and low-risk woodchip production. Soil/vegetation conservation depends on farmers’ status/capacities and environmental awareness; FSC membership added economic-political benefits. Findings are discussed within a regional historic context. Plantations contribute to economic development, but issues persist/emerged in terms of land equity and environmental governance, risks (e.g., plant pathogens), and spaces/impetus for farm-based innovation and adaptiveness

Genetic diversity and cross-species transmission of kobuviruses in Vietnam.

Cross-species transmission of viruses poses a sustained threat to public health. Due to increased contact between humans and other animal species the possibility exists for cross-species transmissions and ensuing disease outbreaks. By using conventional PCR amplification and next generation sequencing, we obtained 130 partial or full genome kobuvirus sequences from humans in a sentinel cohort in Vietnam and various mammalian hosts including bats, rodents, pigs, cats, and civets. The evolution of kobuviruses in different hosts was analysed using Bayesian phylogenetic methods. We estimated and compared time of origin of kobuviruses in different host orders; we also examined the cross-species transmission of kobuviruses within the same host order and between different host orders. Our data provide new knowledge of rodent and bat kobuviruses, which are most closely related to human kobuviruses. The novel bat kobuviruses isolated from bat roosts in Southern Vietnam were genetically distinct from previously described bat kobuviruses, but closely related to kobuviruses found in rodents. We additionally found evidence of frequent cross-species transmissions of kobuviruses within rodents. Overall, our phylogenetic analyses reveal multiple cross-species transmissions both within and among mammalian species, which increases our understanding of kobuviruses genetic diversity and the complexity of their evolutionary history

Detection and Characterization of Homologues of Human Hepatitis Viruses and Pegiviruses in Rodents and Bats in Vietnam.

Rodents and bats are now widely recognised as important sources of zoonotic virus infections in other mammals, including humans. Numerous surveys have expanded our knowledge of diverse viruses in a range of rodent and bat species, including their origins, evolution, and range of hosts. In this study of pegivirus and human hepatitis-related viruses, liver and serum samples from Vietnamese rodents and bats were examined by PCR and sequencing. Nucleic acids homologous to human hepatitis B, C, E viruses were detected in liver samples of 2 (1.3%) of 157 bats, 38 (8.1%), and 14 (3%) of 470 rodents, respectively. Hepacivirus-like viruses were frequently detected (42.7%) in the bamboo rat, Rhizomys pruinosus, while pegivirus RNA was only evident in 2 (0.3%) of 638 rodent serum samples. Complete or near-complete genome sequences of HBV, HEV and pegivirus homologues closely resembled those previously reported from rodents and bats. However, complete coding region sequences of the rodent hepacivirus-like viruses substantially diverged from all of the currently classified variants and potentially represent a new species in the Hepacivirus genus. Of the viruses identified, their routes of transmission and potential to establish zoonoses remain to be determined