Strength Behavior of Single Australian Superfine Merino Wool (ASFW) and


StrengthBehavior of Single Australian Superfine Merino Wool (ASFW) and InnerMongolia Cashmere (IMC) Fibers as a Major Contributor to Mfd andStrength Variations Affected by Different True Length Groups andLength-Diameter Groups

StrengthBehavior of Single Australian Superfine Merino Wool (ASFW) and InnerMongolia Cashmere (IMC) Fibers as a Major Contributor to Mfd andStrength Variations Affected by Different True Length Groups andLength-Diameter Groups

Staplestrength (SS) is among the key determinants of performance of the rawwool during the early-stage processing (1). Research has shown thatabout 80 % of variance in SS between fed various levels of nutritionand sheep bred sheep for low and high SS was positively associatedwith variation in diameter that occurs along and between individualpieces of fiber (2). Genetic variations found in the SS were causedby CVFD between the fibers. Nutrition, on the other hand, influencedSS by causing CVFD along the fibers. An increase in the minimum fiberdiameter (mFD) 1 µm was attributed to the increase in SS by about 5N/ktex. Other research findings have confirmed the existence of astrong association between SS and mFD long the staple (3 4 5).However, it is still not clear whether the association existingbetween SS and mFD should be solely attributed to the amount ofmaterial that is available to put up with the load, or whether thedifferences observed in the average stress at the break (BF) of eachfiber also plays a role in determining variations in SS betweensheep. Studies have also shown that differences in SS, which occursbetween ‘tender’ wool lines and ‘sound’, may be caused bydifferences that occur in BF (6). This contention has been supportedby a significant phenotypic association that occurs between SS and BFfor Merino (7) and Romney (8). However, other studies have indicatedthat such an association is not always obvious (9, 10). Thestrain-stress properties found in the wool fibers has three regionswith distinct mechanical behavior. The desire to interpret thedifferences found in stress-strain behavior and the possible role ofgeometry, molecular and cellular structure of the fiber has been asource of attraction for researchers (11).

Testsfor the specific properties of individual wool fibers can be quiteexpensive and time consuming, which has discouraged researchers whowould like to determine those properties. However, general knowledgehas it that a bundle of fibers is stronger than an individual pieceof fiber. The differences can be attributed to disparity of anindividual fiber in terms of strength. In addition, changes thatoccur in mFD affect the BF of the fiber. Studies [12, 13] examiningthe rectilinear relationship between the square diameter of the fiberand its BF indicate that the scattering of both the BF and mFDfollows the log-normal distribution [14, 15]. However, some naturalfibers (such as wool) show some CVFD along as well as between-fiber.A study has shown that the CVFD alters the tensile behavior of thefiber. In addition, the observed decline in BF tends to be biggerwhen non-uniformity of the fiber is more pronounced [16]. A similarstudy reported a negative impact on CVFD along the fibers that had asimilar average diameter [17]. Moreover, the breaking force andvariation and FD are statically correlated. A study has also shownthat the fiber’s diameter affects the BF that is being tested [14].This implies that one should employ the variations that occur in theminimum fiber across the section thickness (CVmfd),instead of using the CVFD [18]. This relationship is based on two keyassumptions. First, it is assumed that a rectilinear relationshipexists between the minimum FD square and the BF. Secondly, it isassumed that the distribution of mFD follows the log-normaldistribution. The CVBF may also be anticipated from the CVmfdfrom the unprocessed wool, which is attributed to fractures thatoccur in the cross-sectional areas [19]. Morphological flaws in thefiber may also affect its BF [15]. Mechanical behavior of the fibermay be examined using numerical modeling [18].

Currently,the distribution of individual IMC and ASFW strength within thelength of the single fiber as well as the length-diameter groups hasnot been established scientifically. The experiment considered inthis paper tested the impact of CVFD along-fiber and mFD on thestrength behavior. The experiment also examined the correlationbetween CVmfdand CVBF. The changes may be applied to IMC and ASFW fibers in groupsof different true single fiber length (1mm and 10mm intervals) andlength-diameter groups at the fixed gage length, which leads to aresultant indication of the strength of the strength of theparticular fibers.