Jonn A. Foulk

Enzyme-retting of flax and characterization of processed fibers

Enzyme-retting formulations consisting of Viscozyme L, a pectinase-rich commercial enzyme product, and ethylenediaminetetraacetic acid (EDTA) were tested on Ariane fiber flax and North Dakota seed flax straw residue. Flax stems that were crimped to disrupt the outer layers were soaked with various proportions of Viscozyme-EDTA solutions, retted, and then cleaned and cottonized with commercial processing equipment. Fiber properties were determined and crude test yarns were made of raw and Shirley cleaned flax fibers and cotton in various blend levels. Cleaned fibers were obtained from both seed and fiber flax types, but with variations due to treatment. Retting formulations produced fibers having different properties, with enzyme levels of 0.3% (v/v as supplied) giving finer but weaker fibers than 0.05% regardless of EDTA level. Experimental yarns of blended flax and cotton fibers varied in mass coefficient of variation, single end strength, and nep imperfections due to sample and formulation. With cost and fiber and yarn quality as criteria, results established a range in the amounts of components comprising retting formulations as a basis for further studies to optimize enzyme-retting formulations for flax. Under conditions examined herein, Viscozyme L at 0.3% (v/v) plus 25 mM EDTA produced the best test yarns and, therefore, established a base for future studies to develop commercial-grade, short staple flax fibers for use in textiles.

Flax-retting by polygalacturonase-containing enzyme mixtures and effects on fiber properties

Enzyme-retting of flax was accomplished via individual treatment with four polygalacturonase (PGase) containing solutions of various fungal sources and the resulting fibers were characterized. The retting solutions were equilibrated to contain 2.19 U of PGase activity as determined via a dinitrosalicylic acid (DNS) reducing sugar assay. As compared with the buffer control, treatment with the various enzyme solutions increased the yield of fine fibers. Treatment with Aspergillus niger PGase resulted in a 62% increase in fine fiber yield as compared with the buffer control and fiber strength did not statistically differ (P</=0.05) between these treatments. Retting via PGases of Rhizopus origin produced the weakest fibers. These results illustrate that the crude PGases differ in their ability to ret flax and that under the defined experimental conditions the A. niger PGase is a better retting agent. Light microscopy demonstrated the ability of all enzymes to separate fiber from shive and epidermal tissues. Enzyme profiles of the solutions were determined via viscometric assays. Pectinolytic activity was the predominant activity of all enzymes tested. Activity against carboxymethyl cellulose (CMC) was a minor component of all solutions except A. niger PGase for which no activity was detected.

Properties of compression-molded, acetylated soy protein films

Abstract The demand for biodegradable polymers produced from renewable natural resources continues to grow as environmental concerns increase. The objective of this study is to examine how acetylated soy protein isolate performed as a thermoplastic and how the properties of films made from it are affected by composition and morphology. SUPRO® 620 and 660 were modified and acetylated to produce SY7 and SY23 thermoplastic films. These films were formed under various compression-molding conditions to form films of two thicknesses and relative molecular weights. No plasticizer was used in forming these films. Molded films were then evaluated for total and volatile solids, nitrogen content, chemical oxygen demand, flow rate, solubility, X-ray diffraction, 1 H and 13 C NMR, differential scanning calorimetry, infrared analysis, tensile properties, oxygen and water vapor permeability. A comparison of melt flow index values, nitrogen content, total solids, volatile solids, and chemical oxygen demand demonstrated no statistical differences between films, but significant differences from SUPRO® 620 the base material used to form SY7. The SY7 films had lower solubility, lower ‘wet’ tensile strength, and higher oxygen permeability than the SY23 films. Both the SY7 and SY23 films formed at higher compression molding temperatures had higher tensile strengths, increased ‘wet’ elongation, and lower water vapor permeability than the films formed at lower compression molding temperatures. X-Ray diffraction, 1 H and 13 C NMR, differential scanning calorimetry, and infrared analysis exhibited slight or no differences between the SY7 and SY23 films. Compression molded thermoplastics produced from acetylated SUPRO® 620 and 660 appear similar and a possible commercial thermoplastic.

Influence on Flax Fibers of Components in Enzyme Retting Formulations

A series of formulations with varying enzyme and chelator components is tested for flax fiber yield and properties using a recently developed enzyme retting system on Ariane flax grown as a winter crop in southeastern South Carolina. The levels of Viscozyme L, a commercial pectinase-rich enzyme mixture, and Mayoquest 200, a commercial chelator containing 38% ethylenediaminetetraacetic acid (EDTA) as tetrasodium salt, are varied. Enzyme retted flax straw is hand-carded and passed one time through a Shirley Analyzer for cleaning. The chelator level determines the fine fiber (i.e., Shirley cleaned) yield. Fiber strength measured by Stelometer is inversely proportional to enzyme level and not affected by chelator level. Fiber fineness measured by air flow methods is better with higher enzyme levels, and within enzyme levels the higher chelator levels tend to produce fibers with the highest degree of fineness. Relative cost calculations, taking into account fiber yield with costs of enzyme and chelators, provide a framework for determining retting efficiency and fiber quality. Results indicate that fiber properties can be tailored by enzyme or chelator levels. Further, commercial enzyme mixtures and chelators effectively ret flax and can serve as a basis for large scale retting tests.

Influence of water presoak on enzyme-retting of flax

Abstract Enzyme-retting offers an alternative to the current method of dew-retting to extract fibers from flax (Linum usitatissimum L.). Additional steps could improve the efficiency of enzyme-retting and modify the properties of the resulting fibers. Samples of ‘Ariane’ flax, which were grown in South Carolina during the winter and harvested early for quality fiber or late for both fiber and seed, were presoaked with distilled water before enzyme-retting. Soaked, enzyme-retted, and air-dried fibers were compared with unsoaked, control samples for yield and properties, and the water extract (or a freeze-dried portion) was tested in various methods for its influence on enzyme-retting. Presoaking increased fine fiber yield in some cases, but fiber strength at times was reduced. Analyses of the freeze-dried residue from soaking showed a mixture of sugars (128.6 and 101 mg g−1 for early and late harvest, respectively) and aromatic components including p-coumaric and ferulic acids and guaiacyl and syringyl units (3.51 and 3.05 mg g−1 total aromatics for early and late harvest, respectively). Water extracts from presoaking treatments at 1.0–2.0% (w/v) were not inhibitory to the retting fungus Rhizopus oryzae sb or to Viscozyme used for enzyme-retting, based on the Fried test and enzyme activities. Turbidity tests showed slight growth inhibition for Eschericia coli and Streptococcus sp. in the presence of water extracts from early versus late harvest flax at 0.5% (w/v), with those from late harvest flax more inhibitory. Benefits on the efficiency of water presoaking prior to enzyme-retting were moderate and not uniform in this study, and modifications may depend upon particular flax harvests.

Processing techniques for improving enzyme-retting of flax

Information is needed to optimize enzymatic-retting of flax (Linum usitatissimum L.) based on a pectinase-rich mixture and chelators. Seed flax straw from North Dakota in 1998, ‘Natasja’ fiber flax straw from South Carolina in 1993, ‘Ariane’ fiber flax straw field-aged and dried from South Carolina in 1999, ‘Ariane’ fiber flax straw shed-dried from South Carolina in 1999, and Canadian seed flax straw in 1997 comprised diverse samples that were subjected to various tests to improve absorption of enzyme formulation by stems or to evaluate clean fiber yield. Mechanical disruption by crimping stems through fluted rollers at about 80 Newtons gave optimum fiber yield in conjunction with enzymatic-retting and was, therefore, used in further tests to evaluate enzyme absorption. Enzyme absorption was increased significantly for uncrimped flax stems with increased pressure of about 310 kPa or with a vacuum around 88 kPa. Increased pressure was effective more than the vacuum treatment. Samples with minimal post harvest handling were affected more by pressure alterations than samples that had considerable disruptions, such as seed flax straw or field-aged straw. Crimped stems showed little increase in enzyme absorption with alterations in applied pressure. Mechanical treatment of stems by crimping gave the largest increase in enzyme absorption and increased significantly the fiber yields. Based on a variety of sample types, the results suggest that normal atmospheric conditions are satisfactory for penetration of enzyme formulation into crimped stems, and that extraordinary measures are not required to expedite the enzyme-retting process.

Enzyme-Retted Flax Fiber and Recycled Polyethylene Composites

Municipal solid wastes generated each year contain potentially useful and recyclable materials for composites. Simultaneously, interest is high for the use of natural fibers, such as flax (Linum usitatissimum L.), in composites thus providing cost and environmental benefits. To investigate the utility of these materials, composites containing flax fibers with recycled high density polyethylene (HDPE) were created and compared with similar products made with wood pulp, glass, and carbon fibers. Flax was either enzyme- or dew-retted to observe composite property differences between diverse levels of enzyme formulations and retting techniques. Coupling agents would strengthen binding between fibers and HDPE but in this study fibers were not modified in anyway to observe mechanical property differences between natural fiber composites. Composites with flax fibers from various retting methods, i.e., dew- vs. enzyme-retting, behaved differently; dew-retted fiber composites resulted in both lower strength and percent elongation. The lowest level of enzyme-retting and the most economical process produces composites that do not appear to differ from the highest level of enzyme-retting. Flax fibers improved the modulus of elasticity over wood pulp and HDPE alone and were less dense than glass or carbon fiber composites. Likely, differences in surface properties of the various flax fibers, while poorly defined and requiring further research, caused various interactions with the resin that influenced composite properties.

Identification of cotton and cotton trash components by Fourier transform near-infrared spectroscopy

The high demand for cotton production worldwide has demonstrated the need for standardized classification of foreign matter present with cotton. Cotton trash can become comingled with fiber during the ginning and harvesting processes. The conventional instrumental method used to determine the amount of cotton trash present with cotton fiber, the high volume instrument (HVI), lacks specificity in the identification of individual trash components (leaf, etc.). Fourier transform near-infrared (FT-NIR) spectroscopy was investigated to distinguish the individual types of cotton trash from the fiber. In this study, the concept of monitoring differences in spectral bands of cotton and cotton trash by FT-NIR spectroscopy was demonstrated and provided a ‘proof of concept.’ A spectral library based on NIR spectral data and pre-processing methods was developed using cotton and cotton trash samples (hull, leaf, seed coat, and stem) yielding over 97% identification accuracy of cotton trash components in the prediction set.

Progress in enzyme-retting of flax

Abstract New methods for retting flax are sought to overcome problems in the current method of dew-retting of flax. Published data are reviewed and new data presented on the development and testing of a method to ret flax using pectinase-rich enzyme mixtures plus chelators based on cost and fiber yield and properties. In spray enzyme retting (SER), flax stems are crimped to physically disrupt the plants protective barrier and then sprayed until soaked with, or briefly immersed in, an enzyme/chelator formulation. Flax is then incubated at temperatures optimal for enzyme activity, washed, and dried. Pilot scale tests, conducted with 10 kg samples of flax retted with a series of formulations, showed that this method effectively retted flax stems from a variety of sources, including fiber flax, mature fiber flax, and linseed straw. Fiber yield, strength, and fineness were significantly influenced by variations in enzyme-chelator amounts. Cellulases inpectinase mixtures appeared to preferentially attack dislocations in fibers and fiber bundles resulting in loss of fiber strength. Polygalacturonases alone effectively separated fiber from non-fiber components. The SER method proved to be an effective framework for further tests on enzyme-chelator formulations that now must be integrated with physical processing to optimize the extraction of flax fibers based on cost and fiber yield and properties.

Single Cotton Fiber Properties of Low, Ideal, and High Micronaire Values

The Favimat, a single fiber testing machine, is used to quantify the affects of cotton crimp on fibers from three samples consisting of cottons containing low, high, and ideal micronaire values for textile processing. In order to get a better representation of all fibers within these samples, the cotton is further divided into the Suter-Webb array length groups. Following cotton crimp image capturing, fiber fineness is determined by the vibroscope method. The mean values for these samples indicate that cotton containing more crimp in the fibers leads to larger elongation, force to break, linear density, tenacity. and work to rupture. The seven length groups from these cottons indicate that longer cotton fibers appear to contain more crimps per cm. The results suggest that the Favimat is satisfactory for measuring current and future cotton properties.