Properties of thermoplastic composites with cotton and guayule biomass residues as fiber fillers

This study was conducted to evaluate the suitability of using residual plant fibers from agricultural waste streams as reinforcement in thermoplastic composites. Three groups of plant fibers evaluated included cotton burrs, sticks and linters from cotton gin waste (CGW), guayule whole plant, and guayule bagasse. The plant fibers were characterized for physical (bulk density and particle size distribution) and chemical properties (ash, lignin and cellulose contents). A laboratory experiment was designed with five fiber filler treatments, namely control (oak wood fiber as the filler - OWF), cotton burr and sticks (CBS), CBS with 2% (by weight) second cut linters (CBL), CBS with 30% (by weight) guayule whole plant (CGP), and CBS with 30% (by weight) guayule bagasse (CGB). The composite samples were manufactured with 50% of fiber filler, 40% of virgin high-density polyethylene (HDPE), and 10% other additives by weight. The samples were extruded to approximately 32 × 7 mm cross-sectional profiles, and tested for physico-mechanical properties. The CBS and CBL had considerably lower bulk density than the other fibers. Cotton linters had the highest α-cellulose (66.6%), and lowest hemicellulose (15.8%) and lignin (10.5%) of all fibers tested. Guayule whole plant had the lowest α-cellulose and highest ash content. Both CBS and guayule bagasse contained α-cellulose comparable to OWF, but slightly lower hemicellulose. Evaluation of composite samples made from the five fiber treatments indicated that fibers from cotton gin byproducts and guayule byproducts reduced the specific gravity of the composites significantly. However, the CBS and CBL samples exhibited high water absorption and thickness swelling, but the addition of guayule bagasse reduced both properties to similar levels as the wood fiber. The CGP exhibited significantly lower coefficient of thermal expansion. Composite samples with the five different fiber fillers showed similar hardness and nail holding capacity, yet oak fibers imparted superior strength and modulus under flexure and compression with the exception of the compressive modulus of CGB composites. In general, both cotton ginning and guayule processing byproducts hold great potential as fiber fillers in thermoplastic composites.     

Flax-cotton fiber blends: Miniature spinning,gin processing,and dust potential

Development of a flax (Linum usitatissimum L.) industry in North America is desired to supply a domestic source of clean, consistent quality textile fiber for blending with cotton. The objective of this work was to evaluate portions of traditional cotton gin equipment (extractor feeder and lint cleaner) and the “50-g cotton-spinning test (CST)” for flax. Dust was collected on an area sampler in an isolated card room to evaluate dust potential during textile pilot plant processing. Fibers retted by diverse means were cleaned on two separate portions of Continental Eagle's pilot plant cotton gin stand, the Super 96 Feeder and the 24D lint cleaner. Fibers separated and removed from flax stalks by these gin sections were compared against the standard ‘unified line’ processing technique of the USDA Flax Pilot Plant. Test yarns were then made in a CST with cotton and flax blends to provide an indirect measurement of fiber properties that can be related to the retting and gin cleaning processes. The yarns were tested for strength and evenness. Flax fibers that displayed the most favorable properties in the CST were then spun in 23 kg lots in the pilot plant at the following cotton/flax blend ratios: 100/0, 75/25, 50/50, 25/75, and 20/80. With modifications, it appears that portions of a cotton gin stand are able to process adequately small samples of properly retted flax stalks. The CST with minor adjustments provides useful data for ranking and further large-scale flax processing. As expected, it appears that flax fiber can be successfully cleaned on a cotton processing line and that increasing the amount of flax generates additional dust.     

The potential use of Ricinus communis L. (Castor) stalks as a lignocellulosic resource for particleboards

Castor (Ricinus communis L.) stalks, which are a readily available by-product of this plant mainly cultivated for seed production, derived from experimental plantations grown in Northern Greece during the period April–October 1996 were assessed for their suitability as feed stocks for direct substitution of wood in particleboard. The average stalk yield of castor reached about 10 dry t/ha, which is higher than the average yield of forest in temperate zones. After harvesting, castor stalks were dried in a greenhouse to about 12% moisture content, and chipped by an automobile chipper and re-chipped in a hammermill. Castor particles and industrial wood particles mixed in various proportions were used as raw material for one-layer and for the middle layer of three-layer particleboards. A commercial E₂ grade UF-resin was used as binder. Castor particles were characterized by a lower slenderness ratio and lower bulk density than industrial wood particles. The evaluation of the mechanical and hygroscopic properties of panels showed the following results: Partial substitution of wood by castor stalks resulted in the deterioration of all board properties. The presence of the unlignified pith and the configuration of castor particles seem to be responsible for the deleterious effect of castor stalks on board properties. However, comparing the properties of the boards produced in this study to relevant European and American Standards, it was found that, with the exception of screwholding strength for three-layer boards, the experimental one layer-, and three-layer boards containing up to 25% and 75% castor particles respectively meet or exceed the Standards requirements for interior boards.     

A survey of extent of infection and contamination of cotton-seed market and commercial gin samples by Xanthomonas malvacearum (E.F. Smith) Dowson in the Northern States of Nigeria

The extent of infection and contamination of 32 market (hand-ginned) and commercial gin samples of cotton seed by Xanthomonas malvacearum (E.F.Sm.) Dowson, the cause of bacterial blight of cotton, was assessed in the 1979 and 1980 growing seasons at Samaru by scoring the incidence and severity of bacterial blight on seedlings grown from the samples. Cotton-seed samples from various markets in the northern and southern cotton-growing zone, where Samaru 71 is the commercial cultivar, gave higher levels of bacterial blight than samples from the eastern cotton-growing zone where Samaru 72 is the commercial cultivar. There was some variability in blight levels from samples obtained from the northern and eastern zones. Commercial gin samples tended to produce higher levels of bacterial blight than the hand-ginned market samples.     

Effect of resin content and pressure on the performance properties of rubberwood-kenaf composite Board Panel

The possibility of manufacturing rubberwood and kenaf (Hibiscus cannabinus L.) stem medium density fibreboard (MDF) panels at different pressure and resin content were investigated. The effect of mechanisms of interacted independent variables (resin content and pressure) on MDF properties was analyzed. The board performance was evaluated by measuring internal bond (IB) strength, modulus of rupture (MOR), modulus of elasticity (MOE), water absorption (WA) and thickness swell (TS). The test results were statistically analyzed by using response surface method (RSM) to determine the significant independent variables that influenced MDF properties. A mathematical simulation or response surface models were developed to predict the MDF properties (MOR, MOE, IB, WA and TS). The obtained results showed that MDF density and all interactions between the experimental variables were significant factors that influenced the mechanical properties of MDF. At 8 bar and 14 % resin content, the MDF recorded WA of 83.12 % and TS of 20.2 %. It can be inferred that two parameters (resin content and pressure) had positive effect on physical and mechanical properties of MDF. We concluded that resin content show more significant effects on MDF manufacturing as compared to pressure parameters.     

Guayule as a feedstock for lignocellulosic biorefineries using ammonia fiber expansion (AFEX) pretreatment

Natural rubber latex extraction from guayule leaves behind greater than 90% (by weight) of agricultural residue as a feedstock suitable for conversion to biofuels via a thermochemical or biochemical route. Untreated guayule shrub and bagasse (after latex extraction) has shown to be very recalcitrant to enzymatic hydrolysis, necessitating application of a chemical pretreatment to enhance cellulase accessibility. The objective of this work was to carry out detailed compositional analysis, ammonia fiber expansion (AFEX¹) pretreatment, enzymatic hydrolysis and ethanol fermentation for various guayule-derived biomass fractions. Plant feedstocks tested were derived from two sources; (a) a mature 2007 AZ-2 whole guayule shrub plant obtained from USDA/ARS² research fields, and (b) the guayule latex-extracted commercial grade bagasse (62505) from Yulex Corporation. Compositional analysis and enzymatic hydrolysis were carried out using standard NREL³ protocols (www.nrel.gov/biomass/analytical_procedures.html). AFEX pretreatment was carried out using concentrated ammonium hydroxide at elevated temperatures for desired residence times in a pressurized reactor. Yeast fermentations on biomass hydrolyzates were carried out micro-aerobically using Saccharomyces cerevisiae (424A strain) in shake flasks.AFEX pretreatment was found to substantially improve overall enzymatic digestibility by 4-20 fold for both untreated guayule shrub and latex-extracted bagasse. Maximum glucan and xylan conversion achieved for the latex-extracted bagasse was 40% and 50%, respectively. The yeast was readily able to ferment both glucose and xylose to ethanol from the guayule bagasse hydrolyzate with or without external nutrient supplementation (i.e., yeast extract and tryptone). Our results highlight the possible utilization of guayule as a feedstock for lignocellulosic refineries co-producing natural rubber latex and biofuels. However, further process improvements (e.g., lignin/resin extraction and cellulose decrystallization using a modified AFEX process) are necessary to increase the effectiveness of ammonia-based pretreatments for further enhancing enzymatic digestibility of guayule-derived hardwood biomass.     

Chemical constituents and physical properties of guayule wood and bark

About 15 Parthenium species grow in the North American continent with Parthenium argentatum (guayule) as the only species containing harvestable amounts of the rubber latex. The predicted commercialization of the guayule plant for its hypoallergenic latex will result in a significant amount of waste fiber or bagasse biomass that can also be put to use for making wood, paper, and other chemical products, as well as in energy production. Thus, the guayule wood and bark fibers can be considered a new source of plant biomass that may be used as a direct substitute for forest-based wood fiber. However, little information is available on the chemical composition of the wood and bark tissues of guayule (P. argentatum). The objectives of this study were to determine the chemical and fiber composition of guayule and to compare it with other wood fiber sources.Three germplasm lines of mature guayule (Cal-6, AZ-101, and G7-15) and another species of Parthenium (P. tomentosum, PT), juvenile soft maple (Acer rubrum), a deciduous tree, and milkweed (Asclepias syriaca L.) that has long fibers were the plant sources. Separate wood and bark tissues were analyzed for hot water, 1% sodium hydroxide, and alcohol–toluene extracts. In addition, the lignin, holocellulose, alpha-cellulose, and pentosan contents were determined.All the chemical components in the wood fibers for the Partheniums were equal to or greater than the juvenile maple tree. Milkweed had higher alpha-cellulose and lower alcohol–toluene extract contents than both the guayule and soft maple. The guayule bark fibers had more chemical extracts than the wood fibers. The specific gravity of guayule wood was greater than the deciduous wood species. However, the fiber lengths of soft maple wood, guayule wood, and milkweed are similar. Based on the chemical composition, P. argentatum and P. tomentosum could serve as raw materials for the paper and chemical industries as well as for energy production.     

Feeding behavior of a potential insect pest, Lygus hesperus, on four new industrial crops for the arid southwestern USA

Camelina (Camelina sativa), guayule (Parthenium argentatum), lesquerella (Physaria fendleri), and vernonia (Centrapalus pauciflorus [formerly Vernonia galamensis]) are either under limited commercial production or being developed for production in the southwestern USA. Insect pests are a potential economic threat to all these new crops, with Lygus hesperus, the western tarnished plant bug, among the most prominent due to its regional abundance and propensity to feed on reproductive plant tissue. The objectives of this study were to establish baseline data on the feeding behavior and potential impact of L. hesperus on camelina, guayule, lesquerella and vernonia. Behavioral observations of adult females and males, and nymphs of this insect were made in the laboratory. Insects spent ≈35% of their time either probing (=tasting) or feeding on various reproductive and vegetative tissues of guayule, lesquerella or vernonia, but only 20% on camelina. When insects did probe and feed they preferred reproductive tissues, primarily flowers and siliques/achenes, and there were differences in these behaviors relative to crop but not generally to insect stage or sex. Insects probed and fed more on flower tissue of guayule and vernonia compared with camelina and lesquerella, and more on siliques of lesquerella compared with achenes of vernonia. When probing and feeding on vegetative tissue, there was generally a preference for stems compared with leaves in all crops except guayule. Results show that L. hesperus will readily feed on the economically important tissues of all crops, and although research has shown that this feeding did not consistently affect lesquerella yield, further work will be needed to determine if such feeding poses a risk to commercial production of camelina, guayule or vernonia.     

不同颜色色板对茶棍蓟马的诱集效果试验

本文研究了数字化黄板和蓝板对茶棍蓟马的诱集效果试验。3次试验结果均表明数字化蓝板相比黄板对茶棍蓟马具有更好的诱杀效果,且2种色板的诱虫量达到极显著差异(P0.01)。     

不同颜色色板对假眼小绿叶蝉和天敌缨小蜂及其它蜂类的引诱效应?

研究了不同颜色色板对假眼小绿叶蝉诱集效果和对天敌缨小蜂的引诱作用，结果表明黄色板诱集的小绿叶蝉数量最多为68.33头·板-1，紫色板最低5.28头·板-1，黄色板诱集数量极显著高于其他色板（F=10.50，P＜0.01），不同色板的诱集效果为黄色＞绿色＞黑色＞灰色＞红色＞蓝色＞白色＞紫色。不同色板诱集缨小蜂的数量差异极显著（F=16.82，P＜0.01），黄色板诱集缨小蜂数量最多19.00头·板-1，色板引诱缨小蜂的数量为黄色＞绿色＞蓝色＞白色＞红色＞紫色＞灰色＞黑色。黄色板对寄生蜂的引诱力最强，平均每板30.89头，不同色板诱集的缨小蜂与假眼小绿叶蝉的益害比差异不显著（F=1.20， P＞0.05）。     

Effects of extrusion cooking on some functional properties of soy-sweet potato mixtures – A response surface analysis

Mixtures of defatted soy flour and sweet potatoes wereextruded at 0:100, 25:75, 50:50, 75:25 and 100:0ratios in an Insta-Pro 600 single screw extruderoperated at 180, 200, 220 rpm.Oil (3–5%) was added into the mix before extrusion.A 5×3² fractional factorial central compositeresponse surface design was adopted forinvestigating the variables: feed composition, % oil,and screw rotation speed (RPM). Percent oil andscrew speed were randomly investigated at threelevels, while feed composition was randomlyinvestigated at five levels. Effect of extrusioncooking on functional properties: bulk density,expansion ratio, water absorption and solubilityindices and trypsin inhibitor were assessed.Results showed that feed composition and screw speedhad strong influences on the process. The effect ofadding oil, into defatted soybean significantly(p<0.05) affected only trypsin inhibitor content.High extrusion temperature (>130 ^°C), andaccompanying high shear, were the result of thenon-pasting nature of the extrudate. Therefore theproducts may have limited uses.     

Low stress mechanical properties of fabrics woven from bamboo viscose blended yarns

This paper presents the low stress mechanical properties of plain fabrics woven from cotton, bamboo viscose and cotton-bamboo viscose blended yarns. Three blends (100 % cotton, 50:50 cotton-bamboo and 100 % bamboo) were used to produce three yarn counts (20, 25 and 30 Ne). Each of these yarns was used to make fabrics with different pick densities (50, 60 and 70 picks per inch). It was found that bending rigidity, bending hysteresis, shear rigidity, shear hysteresis and compressibility is lower for bamboo fabrics as compared to those of 100 % cotton fabrics. On the other hand, extensibility, tensile energy and compressional resilience are higher for 100 % bamboo fabrics than 100 % cotton fabrics. Higher pick density increases linearity of load-elongation curve, bending rigidity, shear rigidity and compressional resilience. Shear and bending rigidities show very good correlation with the respective hysteresis values.     

Effects of blend ratio and heat treatment on the properties of the electrospun poly(ethylene terephthlate) nonwovens

Semicrystalline poly(ethylene terephthalate) (cPET)/amorphous poly(ethylene terephthalate) with isophthalic acid (aPET) blends with 100/0, 75/25, 50/50, 25/75, and 0/100 by weight ratios were dissolved in a mixture of trifluoroacetic acid (TFA)/methylene chloride (MC) (50/50, v/v) and electrospun via the electrospinning technique. Solution properties such as solution viscosity, surface tension and electric conductivity were determined. The solution viscosity slightly decreased as aPET content increased, while there was no difference in surface tension with respect to aPET composition. The characteristics of the electrospun cPET/aPET blend nonwovens were investigated in terms of their morphology, pore size and gas permeability. All these measurements were carried out before and after heat treatment for various blend weight ratios. The average diameter of the fibers decreased with increasing aPET composition due to the decrease in viscosity. Also, the morphology of the electrospun cPET/aPET blend nonwovens was changed by heat treatment. The pore size and pore size distribution varied greatly from a few nanometers to a few microns. The gas permeability after heat treatment was lower than that before heat treatment because of the change of the morphology.     

Plant population,planting date,and germplasm effects on guayule latex,rubber, and resin yields

Guayule (Parthenium argentatum Gray) is a perennial shrub native to the Chihuahuan Desert. While guayule traditionally has been cultivated for rubber, more recently it is being cultivated for its hypoallergenic latex. Other uses including termite resistant wood products and an energy source have also been identified. However, the effects of various agronomic practices, such as planting and harvesting dates, plant spacing, cutting height and frequency, irrigation frequency, and herbicide application, on latex concentration and yield of newly developed germplasm have not been reported. The objectives of this study were to determine the yield and concentration of latex, rubber, and resin of four guayule lines planted at two populations and two planting dates. Four guayule lines (AZ-1, AZ-3, AZ-5, and 11591) were transplanted at two dates (28 November 2000 and 7 June 2001) and two plant populations (27,000 and 54,000 plants ha^?1). Treatments were replicated four times. Each treatment plot was subdivided into six subplots for harvesting at 6-month intervals beginning 1 year after transplanting. Results showed that transplanting date did not affect plant size or latex concentration or yield consistently. Instead, it appeared that the time of harvest (fall vs. spring) was more important. The sixth (last harvest) in the fall planting date and the fifth harvest date in the spring planting date were the optimum for plant biomass and latex, rubber, and resin concentrations and yields. The lines AZ-1 and AZ-3 were larger, whereas AZ-5 had higher latex and rubber concentrations than the control, 11591. The greater plant population (54,000 plants ha^?1) had higher biomass, rubber, and resin yields than the lower population (27,000 plants ha^?1) at the early harvest dates, but not at the later harvest dates (5 and 6). More studies must to be conducted to determine the optimum plant population and transplanting date for other newly developed guayule germplasm lines.     

Biodiversity of termite (Insecta: Isoptera) in tropical peat land cultivated with oil palms

Termites are the major decomposers in tropical region but yet their occurrences in oil palm plantation especially in peat soil are generally treated as pest. Study of termite species in peat land was conducted in selected oil palm plantations in North Sarawak with 5-7 years old palms and South Sarawak with 13-15 years old palms with two sites in each area. Results of quadrate (25 x 25 x 30 cm) sampling showed termite was significantly higher in relative density with increasing depth of soil (0-10 = 21.23, 10-20 = 42.52 and 20-30 cm = 81.12%) which could be advantaged from being predated by ants (Hymenoptera: Formicidae) which were higher in density from soil surface to 10 cm soil depth with relative density of 31.84%. Modified transect sampling (50x6 m) had successfully sampled 18 species of termites from 2 families (Rhinotermitidae and Termitidae), 5 subfamilies (Rhinotermitinae, Coptotermitinae, Termitinae, Macrotermitinae and Nasutitermitinae) and 11 genera (Coptotermes, Schedorhinotermes, Termes, Macrotermes, Nasutitermes, Globitermes, Amitermes, Parrhinotermes, Pericapritermes, Havilanditermes and Prohamitermes). Both plantation sites have termite dominantly feeding on rotten wood as a result of abundant dead woods. However, Coptotermes curvignathus Holmgren was identified to feed on the living tissues of oil palm causing damage or death of the tree. Study showed higher encounter of soil-feeding termite in longer established plantation. It indicates the gradually shifting of soil condition towards a stabilized environment which favors the successful settlement of soil feeder termite species. Termite control should be more targets specific to avoid harming beneficial termites.     

Preparation and property evaluation of sound-absorbing/thermal-insulating PU composite boards with cushion protection

This study used recycled fibers and inflaming retarding fibers to form composite nonwoven and then compounded with PU foam preparing composite board with sound-absorbing, thermal-insulating and cushion properties. Effects of foam density and composite nonwoven on three properties of PU composite board have studied. Result shows that, with increase of foam density, composite boards had higher sound absorbing coefficient at medium and high frequencies, lower thermal insulation as well as firstly improved and then decreased cushion property. After assessment, the optimal foam density was 60 kg/m³. For diverse requirements, PU foam matches with different kinds of composite nonwoven to achieve excellent cushion property. The resulting composite board can effectively ease hurts from rigid wall, and could be applied in kindergarten, music hall, audio-visual room, pub and recreational centre etc in the future.     

我国转基因棉花研究与应用进展

我国转基因棉花研完近10年，取得重大进：研制出单价Bt和双价Bt/CpTI转基因抗虫棉。已审定的品种正在生产上大面积推广，累计达160khm^2；建立了Bt棉的遗传育种、栽培、良种繁育、抗虫性鉴定、棉铃虫的抗性治理、棉田害虫综合防治以及安全性评估等一整套技术体系；棉花抗病基因工程和棉纤维品质改良的基因工程也取得了进展。     

陆地棉F2代经济性状的对应分析

本文运用时应分析的方法对4个陆地棉亲本及其10个F2代组合共14个材料的16个主要产量性状和品质性状进行了研究，并利用因子距离探讨了材料与性状的关系。结畏表明：对应分析能有效地揭示性状间、品种间、性状与品种间的关系。经分析影响单株产量性状的主要因子是单株有效铃数、单铃重、籽指、衣指。由聚类分析可将供试的14个陆地棉材料划分为3个不同遗传差异的类群。     

Quality of guayule seeds separated by physical attributes

Guayule (Parthenium argentatum Gray) is being developed as a new commercial crop to be grown in arid and semiarid regions. Guayule stands are presently established using transplants; however, establishment by direct-seeding would reduce costs and make production more economical. A major difficulty in field establishment by direct-seeding is the variation in the quality of guayule seeds. Guayule seeds vary greatly in color, size, and weight, which are the attributes believed to be associated with the observed germination differences among and within seed lots. To determine the importance of these attributes, guayule seeds from different seed lots were separated by size (diameter) and color, each separation class was weighed and then seed quality determined by germination percentage and rate. X-ray analysis was used to distinguish filled from unfilled seeds, and this was related to the germination results. In six guayule breeding lines (N565, 11591, AZ-2, AZ-3, AZ-4, and AZ-5), the highest quality seeds were darker (opaque-black and gray), small to medium in diameter (1.4–1.6 mm), and were heavier (a greater proportion of filled seeds). Color appeared to be a more efficient separator for seed quality than seed size; however, separation by size may be acceptable on a large scale and still provide higher quality and more uniform seed lots.     

Study of gene effects for cotton yield and Verticillium wilt tolerance in cotton plant (Gossypium hirsutum L.)

Verticillium wilt (VW), caused by Verticillium dahliae Kleb., is a destructive disease of cotton (Gossypium hirsutum L.). The use of resistant cultivars has long been considered the most practical and effective mean of control. The aim of this work was to study the quantitative genetic basis of Verticillium wilt resistance in Upland cotton by using five genotypes and their possible crosses without reciprocals selecting simultaneously for resistance and desirable agronomic characteristics. Five cotton cultivars and 10 F1s from half-diallel crosses were analyzed for VW resistance. The seed cotton yield, the number of bolls/ plant, and boll weight were measured and Verticillium wilt index (VWI) was estimated during two crop seasons in two different sites each year always on plots with naturally infested soil. Genetic components of variance were analyzed using the Hayman model. Analysis of variance for all characters showed significant differences between genotypes, without genotype-site interaction in most cases. Both, additive genetic variance component (D) and dominance genetic variance components (H1 and H2) were presented in all characters, except for VWI. D was the most important component for boll weight and VWI. Boll weight was the most correlated character with seed cotton yield and VWI. Broad sense heritability was high for boll weight and VWI, moderate for seed cotton yield and low for bolls per plant. Narrow sense heritability was moderate for boll weight, and high for VWI.