A domestic clothes dryer essentially consists of a rotating heated drum in which wet clothes are put. The drum is belt driven by an electric motor and hot air is forced onto the wet clothes through the drum and expelled out through a duct. The drum is enclosed in a sheet metal box. At the bottom corner of the box the drive electric motor is mounted. In order to reduce the structure borne noise, the motor is mounted at four locations through elastomeric mounts. The physical dimensions and mass of the dryer are 53 cm x 60 cm * 72 cm and 26 kg, respectively. Motor rating and Heater rating are 300 W and 1.8 kW, respectively. The drum used inside the dryer for placing the wet clothes is epoxy coated; a maximum of 5.5 kg of wet clothes can be dried in this dryer in an operation cycle. The dryer has a safety cut-off switches which limits the temperature inside the drum to 105°C. All measurements were done in the clothes dryer while running empty. Through sound intensity method noise mapping measurements it has been found that some of the major source of noise in a clothes dryer are the rectangular sheet metal shell, the motor and the blower exhaust. Various derivatives of jute are used for the noise control; jute felt is stuck to the in­ner walls of the rectangular shell by glue, jute felt is attached to the rear panel of the shell, the duct which carries the hot air out of the clothes drum is lined with jute fiber faced of 400 gsm jute textile. An overall noise reduction of 6 dB was obtained by such a treatment. Fig. 6.20 shows an opened view of the jute-lined shell of the clothes dryer. The octave band spectrum of the radiated sound power of the treated and untreated clothes dryer is shown in Fig. 6.2162. A similar type of treatment can be done for clothes washer, dishwasher and window type room air-conditioner.

Composites are attractive materials that consist of two (or more) distinct constitu­ents, which when coupled together provides a material with completely different properties from those of the individual original components.1 Composite materials

are unique because they combine material properties in the manner not existing in nature. Such combination often results in lightweight materials with high stiffness and tailored properties for specific applications.2 Glass fiber is the most dominant fiber and is generally used in 95% of cases to reinforce thermoplastic and thermoset composites. Recent research developments manifested that in certain composite ap­plications, natural fibers demonstrate competitive performance to glass fibers.2 The most widely used composite in industries today is glass fiber-reinforced compos­ite. Although glass fiber composite has numerous advantages, it also has demerits. Glass fiber can cause irritation to the skin, eyes and upper respiratory tract. These inherent health hazards of glass fiber has fuel the extensive search for safer, cheaper and maybe better fiber than glass fiber.3,7 Natural fibers are highly potential alterna­tives for glass fibers. Natural fibers are less abrasive to tooling and not causing as many respiratory problems for workers or consumers. Moreover, they are low cost and have loading bearing potential. Therefore, the use of natural fiber based com­posites has extended to various sectors, such as aircraft, construction, automotive, etc. (Fig. 9.1).8

Biodegradable composite types are not strange materials to human civilization. Their use dates to antiquity, such as the Great Wall of China whose construction

started initially in 121 B. C. as earth works were connected and made strong by clay bricks made of local materials initially using red willow reeds and twigs with gravel during the Han dynasty (209 B. C.). The Wall was later built with clay, stone, wil­low branches, reeds, and sand during the Qin dynasty (221-206 B. C.).8,10 However, biocomposite materials have transited through significant developments in terms of using different raw materials, processes and even applications. The history of fiber — reinforced plastics began since 1908 with cellulose fiber in phenolics, later extend to urea and melamine and reaching commodity status with glass fiber reinforced plastics. The fiber reinforced composites industry is now a multibillion-dollar busi­ness.11

Biocomposites are broadly defined as composite materials made from natural fiber and petroleum derived nonbiodegradable polymers (i. e., PP, PE) or biodegrad­able polymers (PLA, PHA). The latter category of biocomposites which are derived from natural fiber and biobased polymers (bioplastic/biopolymer) are likely to be more environmental friendly and such composites are termed as green composites (Fig. 9.2) (John and Thomas, 2008).11

Tensile tests on fibers were conducted on a tow (strand) disassembled from the fab­ric. The tows in the longitudinal direction in the fabric were separated from the ones in the orthogonal direction. Tests were carried out for both series separately. The tensile properties of the fiber tow were determined at room temperature and 50% relative humidity on an Instron 5548 microtester machine, with crosshead distance of 50 mm and speeds of 120 mm/min. The maximum load at break was recorded for each specimen. A minimum 10 specimens were tested for each type of sample.

The tensile properties of the composites were evaluated at room temperature and 50% relative humidity on an Instron 5500R machine, with crosshead speeds of 5 mm/min according to ASTM 3039-00. A minimum 5 specimens were tested for each type of sample.

As indicated already, the fiber-matrix interface quality is very important to promote successful reinforcement of composite materials. There are a number of physical and chemical methods to optimize the interface for varying degrees of efficiency for the adhesion.43

14.4.4 PHYSICAL METHODS

Physical methods for improving the adhesion of surfaces attempt to enhance or im­prove existing surface chemistry or functionalities. For example, surface fibrillation is one method that has been previously used; this is a type of refining or homogeni­zation (NFC, vide supra) that takes a top-down approach in increase the surface area of the materials under study. What this means is that the macrofibers are “opened” up to reveal more of the micro and nano-fibrils that compose the fibers. Such an approach allows for the native high surface energy and area to be increased and promote adhesion. Another method is electric discharge that includes corona or cold plasma. Cold plasma has been used to increase bondability without significantly im­pacting the bulk properties of the substrate treated. Carlsson44 was able to show via a hydrogen plasma treatment of a pure cellulose substrate that the hydroxyl content on the surface was diminished to provide lower molecular weight fragments that were more hydrophobic.

The highly transparent and flexible films prepared using NFCs exhibited a dras­tic improvement mechanical properties, with a maximum enhancement in Young’s modulus of 78% and 150% for high molecular weight chitosan and water-soluble high molecular weight chitosan (WSHCH), respectively with 20 wt.% of NFC load­ing; and of 200% and 320% for low molecular weight chitosan and water-soluble low molecular weight chitosan, respectively with 60 wt.% of NFC loading. The tensile strength values were in closer agreement with the trend of modulus values. As it can be assumed from a classical reinforcement effect, the values for elongation at break were reduced.39 Similar trends was also observed using bacterial cellulose.44

In order to manufacture vast quantities of purified spider silk protein for wet spin­ning methodologies, the expression system for protein production needs to be ro­bust, cost-effective and offer rapid biochemical strategies to purify the recombinant fibroins for the spinning process. At least five other natural fibroin cDNA sequences have been used for recombinant expression, which include MaSp2, the tubuliform spidroins TuSp1 and ECP-2, PySp2, and AcSp1 (Fig. 1.6).39’5254a However, despite the availability of the seven different spidroin genetic blueprint sequences, the ma­jority of the recombinant expression studies have focused on dragline silk fibroins, specifically MaSp1. Currently, it is unclear how many companies are deeply in­vested in the large-scale production of spider silk. A few companies with spider silk interest have surfaced in the news, including a San Francisco Bay Area company, Refactored Materials, Inc., as well as a Japanese startup company, named Spiber®. Both have been pursuing the process for large-scale production of synthetic spider silk fibers in either yeast or bacteria, respectively. Spiber® has reported that it can produce several hundreds of grams of recombinant spider silk protein per day.

If tons of spider silk materials are to be manufactured for global distribution, scaling the procedure to synthesize sufficient quantities of fibroins from transgenic

cells or organisms must be optimized. Therefore, identifying the most efficient ex­pression system for recombinant spider protein production has been intensely inves­tigated and still remains as a barrier. So far, it would seem that bacteria or yeast are emerging as the likely candidates. Based upon expression studies, for example, in the methylotrophic yeast P. pastoris, it is reasonable to assume that expression of some recombinant fibroins can achieve 1 g/L of culture.72 Typically, one gram of pu­rified recombinant spidroin could produce about 29,527 feet of silk. To produce one ton of spider silk, which is the equivalent of approximately 998,412 grams, it would require about 100,000 L of culture. This is well within the range of some large in­dustrial sized fermenters that have volume capacities that can exceed 25,000 L. One of the chief advantages for using P. pastoris includes the secretion of the recombi­nant proteins into the extracellular medium, which allows for rapid purification of proteins due to the fact that little, if any, other proteins are secreted into the liquid media. Furthermore, it eliminates the need to analyze the cells and restart cultures for expression, a process that can be tedious, increase production times, and result in higher production costs and manufacturing prices. Additionally, P pastoris can be grown in bioreactors to high densities on mineral salt media and has been shown to be effective for expression of very large and complex proteins, such as collagens, which also require the coexpression of collagen prolyl 4-hydroxylase for the ther­mal stability of collagens.73 As more is revealed about the proteins involved in the spider silk assembly pathway, these components can be integrated into the expres­sion system and presumably lead to better products.

1.4 CONCLUSION

Over the past several years, the spider silk community has advanced their under­standing regarding the protein compositions of the different fiber types. With these advances, many partial cDNAs and several complete genetic blueprints coding for spider silk proteins are available for recombinant protein expression. Additionally, wet-spinning methodologies that use purified, recombinant spider protein as spin­ning dopes are becoming more commonly reported in the literature. Still, the need for further progress to increase the quantities of recombinant proteins manufactured by host cells, along with improvements and new strategies for mechanical spinning will need to be developed if spider silk synthesis is to successfully reach large-scale production with material properties that rival natural silks. Undoubtedly, the differ­ent applications for spider silk proteins as biocomposites seem endless.

1.5 ACKNOWLEGMENT

We thank Drs. Joan and Geoff Lin-Cereghino with expression studies in P pastoris. In addition, we thank Yang Hsia, Eric Gnesa, Felicia Jeffrey, Thanh Phanm, Connie Liu, Christine Ho, Lisa Pham and Ryan Pacheco for their valuable contributions. We also are indebted to Dr. Mark Brunei at the University of the Pacific, Department of Biology, for his assistance with the scanning electron microscope.

KEYWORDS

• Biocomposites

• Mechanical Properties

• Protein

• Spider Silk

The T’s measured by DMA for SPE/TA(1/1) and SPE/QC(1/1.2) were 95 °C and 86 °C, respectively, whose values were much lower than that of the cured conven­tional DGEBA (>100 °C). Therefore, when industrially available and inexpensive SPE is combined with a bio-based phenolic hardener, the hardener having a lower hydroxy value and a higher aromatic content than TA should be used. Vanillin (VN) is contained in essential oil of clove or vanilla, and is also prepared from bio-based
eugenol or guaiacol. In this section, the synthesis of a bio-based novolac is exam­ined by the reaction of PG and VN.26 As a result of the spectral analyzes of the ob­tained reaction product, it was found that pyrogallol-vanillin calixarene (PGVNC) mainly composed of guaiacyl pyrogallol[4]arene is formed. Although aryl pyro — gallol[4]arenes synthesized by the reactions of pyrogallol with benzaldehyde, p — methylbenzaldehyde and p-methoxybenzaldehyde, etc., are known compounds, their calixarenes have attracted little attention because of the very poor solubility in common solvents.7879 In contrast, the PGVNC can be easily used as building blocks of polymeric materials because of the good solubility to some organic solvents.

The reaction of PG and VN in the presence of p-toluenesulfonic acid gave PGVNC as a pale purple powder in 51% yield (Fig. 4.35). The obtained PGVNC was soluble to tetrahydrofuran, Ж. Ж-dimethylformamide and dimethylsulfoxide, and insoluble to water, methanol, ethanol, acetone, chloroform, ethyl acetate and hexane. Fig. 36 shows a FD-MS spectrum of PGVNC. A strong peak of m/z 1040 (C56H48O20:4PG+4 VN-4H2O) corresponds to a calix[4]arene, guaiacyl pyrogallol[4] arene. Other peaks at m/z 520, 398, 262 and 126 correspond to (C28H24O10: 2PG+2 VN-2H2O), (C22H22O7: PG+2 VN-2O), (C14H14O5: PG+VN-O) and (C6H6O3: PG), respectively. Although the peak of m/z 520 corresponds a calix[2]arene, the struc­ture would not be possible because of highly strained structure. From the MS spec­trum of PGVNC, we could not decide whether the peaks other than 1040 are the fragment peaks of guaiacyl pyrogallol[4]arene or due to the compounds contained in PGVNC.

Figure 4.37 shows the ‘H-NMR spectrum of PGVNC measured in J6-DMSO. Although novolac derivatives prepared from phenols and aldehydes generally show complex spectral patterns because of different substitution positions of benzene ring and degree of polymerization, PGVNC showed a simple spectral pattern, suggest­ing the formation of a single product with a symmetrical structure. Almost the main ‘H-signals can be assigned to the protons of guaiacyl pyrogallol[4]arene. The ‘H signals at 7.89 (s, 4H), 7.70 (s, 2H), 7.63 (s, 2H), 7.43 (s, 4H) and 7.19 (s, 4H) are assigned to the protons of phenolic hydroxy groups of PGVNC, because the ‘H signals disappeared by the H-D exchange by the addition of D2O. The fact that two separated hydroxy protons are observed at 7.70 (s, 2H) and 7.63 (s, 2H) in­dicates that there are two pairs of hydroxy groups with a different conformation. The ‘H signals of guaiacyl group were observed at 6.33 (d, 4H, Hb, J = 8.0 Hz), 6.17 (s, 4H, Hd), 6.10 (d, 4H, Hc, J = 8.0 Hz). The ‘H-signals of pyrogallol ring were observed at 6.06 (s, 2H, Ha) and 5.58 (s, 2H, Ha), indicating that there are two kinds of pyrogallol rings with a different conformation, and that thermodynami­cally stable rctt (cis-trans) isomer is preferentially formed. Although the ‘H NMR spectral data of aryl pyrogallol[4]arenes have not yet been reported because of the very poor solubility, the reported NMR data of acylated aryl pyrogallol[4]arenes in CDCl3 resemble those of PGVNC.78 The stable conformation of the PGVNC with rctt configuration was calculated by MM2. Fig. 38 shows the calculated structure of the rctt PGVNC. The four-pyrogallol units in the calixarene ring were divided into two groups with two pyrogallol rings at almost perpendicular direction and other two pyrogallol rings nearly in horizontal position. The stretching direction of two perpendicular pyrogallol rings is opposite. One pyrogallol ring is upper standing and the other is upside down. The four side gauiacyl groups are also divided two groups with two neighboring guaiacyl groups at left side, while other two-guaiacyl groups locating at right side. For acylated ^-methylphenyl pyrogallol[4]arene and acrylated ^-methoxyphenyl pyrogallol[4]arene, similar structure is confirmed by the X-ray crystal structure analysis.78

The water absorption of jute-based biocomposite samples were measured according to ASTM D 5708. This test is carried out to determine the amount of water absorbed and performance of the materials in water environments. This is very similar to the moisture absorption test. Three square shaped samples of 3.0 cm x 3.0 cm of 5% natural rubber based jute composite were kept in an oven at a temperature of 100°C. Then weight of the three samples were measured. After that these samples were kept in a Petri dish full of distilled water. Then after 24 h and 48 h, the weight of the samples were taken and the water absorption was calculated using the Eq. (3).

W — W

Water absorption, Wa = —1——- 1 x100 (3)

W

where W1 is original weight of the sample and W2 is final weight of the sample after 24, 48 and 120 h.

The results of water absorption test are shown in Table 6.2. The percentage of the water absorption gradually increases with time and then it reaches a saturation point and an average of 114% of water is absorbed at the end of 120 h.

The first tests are carried out for reinforcement 1 with an orientation 0°. The blank holders’ pressure is set to 1bar. The preform in its final state is presented on Figs. 7.6a and 7.6d. The final shape is in good agreement with the expected tetrahedron punch without large wrinkle or un-weaving on the useful zone. Only very small wrinkles can be observed on corners of the edges for both reinforcements 1 and 2. At the local scale, on faces and edges, the tow buckling defects (Figs. 7.6.b and 7.6.d) and misalignment of tows (Fig. 7.6.b) are identified. Tow buckling only takes place on the Face C and on the opposed edge (between Faces A and B) whereas misalign­ment of tows is observed on all faces.

Depending on the initial orientation of the fabric, tow buckling (Fig. 7.6.b) ap­pears on faces and on one edge of the formed tetrahedron shape. These buckles zones converge from the bottom of the useful shape up to the triple point (top of the tetrahedron) (Fig. 7.6.d) Due to this defect the thickness of the preform is not ho­mogeneous. The height of some of the buckles can reach 3 mm near the triple point. Due to this thickness in-homogeneity generated by these buckles, the preform could not be accepted for composite part manufacturing.

At the fabric scale, the buckles are the consequence of out of plane bending of the tows perpendicular to those passing by the triple point. The tows passing by the triple point (vertical ones, or weft tows for orientation 0°) are relatively tight. They seem to be much more stressed than the warp tows, perpendicular to the one pass­ing by the triple point. It can be expected that the size of the buckles depends on those tows tension. In this zone, there is no homogeneity of the tensile deformation. This is illustrated by the orientation of the tows perpendicular to the one passing by the triple point on both sides of the buckle zone (drawn Fig. 7.2.d). These tows are

curved instead of being straight, and this phenomenon is probably at the origin of the buckles. The tow misalignment is also observed for reinforcement 2 (Figs. 7.7.a and 7.7.b) globally at the same location as for reinforcement 1. However, tow buck­les do not appear on the faces of the shape. Only very small buckles can be observed on the edge opposed to Face C in the case of a 0° orientation with a low blank holder pressure of 1 bar, as observed in Fig. 7.8.

However, tow buckles do not appear on the faces of the shape. Only very small buckles can be observed on the edge opposed to Face C in the case of a 0° orienta­tion with a low blank holder pressure of 1 bar, as observed in Fig. 7.8.

If tow buckles and small wrinkles can be observed on the shapes formed using the tetrahedron punch, the causes of the defects have not yet been discussed. It is therefore proposed to discuss the issues concerning the appearance of the defects that can be encountered during sheet forming of natural fiber based woven fabrics.

Sugar palm tree is one of multipurpose trees grown in Malaysia. The inner part of sugar palm stem contains starch. It was used as raw material for starch and glue sub­stances.79 For the production of one ton of starch, ten to 20 trees are needed which suggests that one tree can produce 50 to 100 kg of starch.76 This accumulated starch is harvested from the trunk of matured palms (after 25 years) and can be applied as ‘green’ material. Starch will act as biopolymer in the presence of a plasticizer such as water, glycerol and sorbitol at high temperature. Previously, the characteriza­tion of sugar palm starch as a biopolymer have been done by using the glycerol as a plasticizers.76 From the research, it was found that the tensile strength of SPS/ G30 showed the highest value 2.42 MPa compared to the other concentration of the plasticizer. The higher the concentration of the plasticizers, the higher the tensile strength of plasticized SPS and optimum concentration was 30 wt.%. The tensile strength decrease to 0.5 MPa when concentrations of plasticizer was 40 wt.%. As the plasticizer content increased to 40%, not enough SPS to be well bonded with glycerol and thus poor adhesion occurred which reduce the mechanical properties of SPS/G40. This result well agreed with the finding of Laohakunjit and Noomhorm80 who claimed that the films outside this range are either too brittle (< 20 wt.%) or too tacky (> 45 wt.%).

Generally, as the plasticizer increase, the tensile strength and elongation of plas­ticized SPS increase, while the tensile modulus decreased. This phenomena indi­cates that the plasticized SPS is more flexible when subjected to tension or me­chanical stress. The results from this study prove the finding done by Beerler and Finney81 whereby they reported that the plasticizers such as glycerol will interfere the arrangement of the polymer chains and the hydrogen bonding. It is also most likely affect the crystallinity of starch by decreasing the polymer interaction and cohesiveness. Thus, this make the plasticized SPS become more flexible with the increasing of glycerol.

For the thermal properties, the Tg of dry SPS reaches 242.14 °C and decreased with addition of glycerol. This value was higher than Indica rice starch where Tg values was237°C.82 Meanwhile, Myllarinen et al.83 claimed that for dry starch the Tg reaches 227 °C. The sample with high glycerol concentrations showed lower Tg values and Tg of starch without plasticizer were higher than those of samples with glycerol (Table 9.3). This behavior was also observed by Mali et al.84 for yam starch and by Forssell et al.33, for films based on barley starch, in both cases with glycerol as plasticizer. According to Guilbert and Gontard85, plasticization decreases the in­termolecular forces between polymer chains, consequently change the overall cohe­sion, leading to the reduction of Tg. Mitrus86 has been claimed that the plasticizer decreased Tg because it facilitates chain mobility. Brittleness is one of the major problems connected with starchy material due to its high Tg.87 In the absence of plasticizers, starch are brittle. The addition of plasticizers overcomes starch brittle­ness and improves its flexibility and extensibility of the polymers.