jane gay kveton dever, b.s.t.t - tdl

THE INFLUENCE OF COTTON FIBER PROPERTIES ON THE

EFFECTIVENESS OF LINT CLEAiaNG IN GINNING

JANE GAY KVETON DEVER, B.S.T.T.M

A THESIS

CROP SCIENCE

Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for

the Degree of

MASTER OF SCIENCE

Approved

Accepted

May, 1986

c.(^p*^ ACKNOWLEDGEMENTS

I am deeply indebted to the members of my committee,

Drs. John Gannaway and Jack Gipson, co-chairmen. Dr. Robert

Steadman, Mr. Roy Baker and Mr. Harvin Smith for their

direction of this research.

I appreciate the patience and guidance of Mrs. Nell

Powell of the Textile Research Center. I also wish to thank

Mesdames Oleda Hollingsworth, Renett Feazell, Mary Rains,

Billye Rhodes, Whitney Womack, Rebecca Youngblood and

Pauline Williams for their assistance in testing the

fiber samples used in this research.

11

TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS 11

LIST OF TABLES iv

LIST OF FIGURES vi

ABSTRACT vi i

1. INTRODUCTION 1

2. REVIEW OF LITERATURE 3

3. MATERIALS AND METHODS 18

4. RESULTS 21

4. DISCUSSION 38

6. CONCLUSIONS 44

LIST OF REFERENCES 45

111

LIST OF TABLES

Page 1. Cultivars, Identification Number, And

Initial Fiber Properties 20

2. Split Plot Analysis Of Variance 21

3. Peyer AL-101 Length Array Results 29

4. Shirley-IIC Micronaire, Fineness/Maturity, Raw Fiber Neps/Grain And Non-Lint Content 30

5. Stelometer Strength And Elongation, Spinlab Estimated Count Strength Product Results 32

6. Summary Of Peyer Fiber Length Array Characteristics - Cultivar Variations 33

7. Summary Of Gin Treatment Effects On Length Array Characteristics 34

8. Analysis Of Variance For Length Characteristics As Affected By Cultivars, Gin Treatments, And Their Interaction 35

9. Changes In Length Array Properties Due To Cleaning 36

10. Summary of Cultivar Variation In Tensile Properties 37

11. Summary Of Gin Treatment Effects On Tensile Properties 38

12. Analysis Of Variance For Tensile Properties As Affected By Cultivars, Gin Treatments, And Their Interaction 39

13. Summary Of Fineness/Maturity, Non-Lint And Raw Fiber Nep Data 40

14. Summary Of Gin Treatment Effects On Fineness/ Maturity, Non-Lint And Raw Fiber Nep Data 41

IV

15. Analysis Of Variance For Other Fiber Properties As Affected By Cultivars, Gin Treatments, And Their Interaction 42

16. Correlation Coefficients Between Length Reduction And Initial Fiber Properties 48

17. Correlation Coefficients Between Neps And Initial Fiber Properties 49

v

LIST OF FIGURES

Page 1. Effect Of Lint Cleaners On Classer's Grade

And Staple Length, And Bale Weight And Value 16

2. Effect Of Saw Lint Cleaners On Nep Count, Yarn Strength And Appearance 17

3. Change In Fiber Length Proportions Of Tamcot SP-21S After Two Lint Cleaners 27

4. Change In Fiber Length Proportions Of NX-1 After Saw Ginning 28

5. Effects Of Fiber Parameters On Increases In Fibers < 0.75 Inch 47

VI

ABSTRACT

Seven sources of cotton with a wide range of fiber

properties were saw ginned and processed through tandem saw

lint cleaners or through an aggressive carding type cleaner.

Lint cleaner induced changes were compared to initial fiber

properties from roller ginned samples to determine if a

relationship existed between fiber properties and fiber

damage caused by saw ginning or lint cleaning.

Lint cleaners decreased fiber length, while increases

in short fiber content, maturity level and nep density also

were noted. Strength, elongation and micronaire were

unaffected. Examination of complete fiber length

distributions showed an increase in the proportion of fibers

shorter than 0.75 inches. Fiber damage was assessed as the

increase in fiber content below 0.75 inches after lint

cleaning. An increase in neps was also considered to be

fiber damage.

Fiber length damage from roller ginned to saw ginned

samples is negatively correlated with initial fiber strength

and strength X elongation. Change due to lint cleaning is

positively correlated to fiber fineness. Strength X

Vll

fineness, or an estimate of individual fiber strength shows

the best relationship to fiber length damage. As the

estimated parameter of individual fiber strength increases,

less length damage is incurred during lint cleaning.

Initial nep level and final nep level are higher when

fibers are finer and upper quartile length and non-lint

content of the fiber sample increases. Change in nep level

caused by lint cleaning has no significant relationship to

initial fiber properties. Mechanical manipulation of

fibers, regardless of initial fiber quality, is conducive to

nep formation.

Vlll

CHAPTER 1

INTRODUCTION

The first attempt to mechanically remove trash from

cotton was a steam engine-driven wooden cleaner constructed

by a Mississippi slave in 1840. Increased acreages and

faster harvesting necessitated additional cleaning equipment

to process the progressively trashier cotton brought to the

gin. The mechanical harvesting methods that came into

extensive use following World War II were so fast that the

ginning season gradually shrunk from six months to six or

eight weeks. Higher ginning speeds along with increased

cleaning equipment were necessary to gear the gin to the

new harvesting conditions. When rates and speeds are raised

at the cotton gin, the problem becomes one of preserving the

initial quality of the lint to meet the requirements of the

producers' customer, the textile industry.

The purpose of this research is to study the

interactions of cotton fiber properties during ginning and

lint cleaning and determine if there are varying degrees of

damage potential among fiber types.

The general effect of lint cleaning on fiber quality is

well understood. The results of lint cleaning on economic

factors such as grade, staple length, and micronaire have

been stated. Information on how to maximize lint cleaning

with minimal fiber damage can be acquired by examining the

interactions of other fiber properties on the severity of

lint cleaner effects on fiber quality. Some specific

questions to consider include: (1) Does fiber strength have

an effect on the magnitude of length decreases resulting

from lint cleaning? (2) Is the nepping potential of some

fibers greater than for other fibers? (3) Does lint

cleaning affect the average fineness and maturity of a

cotton sample by removing immature, or coarse, fibers?

CHAPTER 2

REVIEW OF LITERATURE

2.1 The History of Lint Cleaning

The climate of the southern United States is favorable

for growing cotton, but originally production had been

limited to the amount of lint that could be removed from the

seeds by hand. The ginning bottleneck was broken by Eli

Whitney's 1794 invention of the mechanical saw gin. This

gin removed fibers from the seed 100 times as fast as it

could be done by hand. The first major improvement in the

gin was made by Hodgen Holmes. His developments made the

gin operation continuous rather than a batch process.

Changing ginning from an intermittent to a continuous

operation made it more efficient and also increased capacity

(Moore, 1977).

Since ginning was no longer a limiting operation,

cotton acreage expanded. Workers no longer harvested

cotton from the stalk as carefully as before and more trash

was picked with the cotton. The trash made the fiber less

desirable to the mills because it did not spin as well and

there was more waste. Initially, the trash was picked from

the cotton by hand.

It is quite probable that there were many attempts to

clean cotton mechanically. The first evidence available is

a steam driven wooden cleaner constructed by a slave in

1840.

Additional cleaning equipment to handle trashier cotton

continued to increase the cost of ginning. Commercial

installations of ginning operations began to replace

plantation gins in the early 1900's. The more efficient

machinery became in removing trash, the rougher harvesting

methods became. A point was reached where the damp, trashy

cotton could neither be cleaned nor ginned successfully. In

1926, Mississippi Valley farmers, through Congressmen J.P.

Buchanan of Texas and W.M. Whittington of Mississippi asked

the U.S.D.A. to develop a method for drying cotton to

facilitate cleaning. The seed-cotton drier, the cotton-lint

cleaner and the stick and green-leaf machine rival the

invention of the gin itself in their importance to the

cotton industry, playing a major role in making the use of

mechanical harvesting economically feasible (Mangialardi,

1979) .

The mechanical harvesting methods that came into

extensive use following World War II made it possible to

harvest cotton so rapidly that the gin again became the

bottleneck. High capacity machines were developed that

would remove the fiber from the seed about 4 times as fast

as gins then in commercial production. Seed cotton must be

dried, cleaned, and ginned at a rate as high as 18 tons an

hour. The handling of this volume of material without fiber

damage requires automatic drying systems that do not overdry

the fibers, and more efficient lint cleaners. The saw gin

cannot improve individual fiber quality; it can only

preserve it. Present research is aimed at preserving lint

quality while operating at efficiencies dictated by the

capacity of mechanized harvesting.

2.2 Factors Affecting Fiber Quality in Lint Cleaning

Lint cleaners were developed specifically for removing

leaf particles, motes, grass, and bark left in the cotton

after the fibers were removed from the seed. Many

considerations are involved in improving the effectiveness

(maximum cleaning, minimum fiber damage) of lint cleaners.

2.2.1 Preparation

Cotton fiber moisture control is important for

obtaining the optimum fiber quality from the seed cotton

delivered to the gin. Damp cotton does not clean as well as

dry cotton and produces a sample of rough appearance that is

often downgraded by the cotton classer. Before the

widespread use of lint cleaners, cotton was dried to very

low moisture levels to obtain the highest possible grades.

Research has established that cotton fiber strength is

directly proportional to fiber moisture content (Grant

et al., 1962). The frequency of fiber breakage increases as

moisture content decreases. The optimum moisture level

range for efficient cleaning with minimum fiber damage is

said to be 6.5-8% fiber moisture content (Leonard et al.,

1970). The development of the seed cotton drier has

expanded the use of cleaning machinery since dry cotton can

be cleaned more readily. Before seed cotton is ginned, it

may go through a series of cylinder cleaners and extractors

to remove burs, sticks, stems, hulls, dirt and even tramp

metal (Pendleton and Moore, 1967). Extracting large

materials, such as burs or sticks, may increase the amount

of fine trash in the lint. The bur machine tends to

pulverize large trash particles and create fine trash

(Franks and Shaw, 1959). The amount of trash in the lint

prior to lint cleaning can affect the potential of the

cotton to form neps (Read and Kirk, 1978).

2.2.2 Operating Parameters

The uniformity and thickness of the lint batt and the

manner in which it is delivered to the lint cleaner saw

teeth can affect fiber quality. Increasing the combing

ratio and saw speed increases cleaning efficiency, but

damages fiber quality. Higher ratios and saw speeds will

result in high fiber breakage and increased nep frequency,

but speeds must be high enough to ensure acceptable

efficiency (Mangialardi, 1970).

2.2.3 Multiple Lint Cleaning

Eighty percent of the gins in the United States use two

or more lint cleaners placed in series so that the same lint

passes through all of them (Afzal & Afzal, 1985). As the

number of lint cleaners increases, grade tends to increase.

However each succeeding cleaner gives less grade

improvement than the preceding one (Mangialardi, 1980). When

grades are improved, bale weights are reduced and staple

length may dec ease. Figure 1 illustrates this relationship.

Increasing the number of saw lint cleaners at the gin

decreases manufacturing waste during spinning, but yarn

strength and appearance are adversely affected. Figure 2

shows the effect of multiple lint cleaning on spinning

performance. From a spinning standpoint, the use of more

than•two saw lint cleaners in series is discouraged (Looney

et al., 1963).

2.3 Fiber Properties

The basic characteristics a staple fiber must possess

to be spun into a yarn are: it must be at least 1000 times

longer that it is wide (sufficient length and fineness); it

must be strong and flexible enough to withstand processing;

it must have some degree of inter-fiber cohesion (Cook,

1984). The specific quality requirements of the automated

mills adopted by the textile industry following World War II

are high and stringent. Spinning performance, measured by

8

frequency of ends down, may be dictated more by preparation

and cleanliness than by fiber properties, especially at

finer counts (Price, 1984). If these requirements are not

met, the textile industry may turn to synthetic raw

materials.

2.3.1 Grade

Lint cleaners improve grade by extracting foreign

matter, blending spots, and improving preparation and color

classification (Mangialardi, 1980). Grade increases by lint

cleaning are limited by offsetting losses of staple length

and bale weight. The amount of recommended lint cleaning

depends on the original grade and the price spread between

grades (St. Clair and Roberts, 1958).

2.3.2 Cohesiveness

Mechanical cleaning of cotton is preferred over more

unorthodox procedures, such as scouring cotton prior to

processing, because it preserves inter-fiber cohesion.

Cotton is unique relative to other staple fibers because its

cohesiveness is imparted by natural convolutions caused by

the fibers collapsing when the lumen dries out (Rollins,

1949). Cleaning lint by wet-processing techniques tends to

swell the fibers so that they lose their convolutions.

2.3.3 Length Characteristics

Decrease in fiber length caused by fiber breakage is

an obvious detrimental effect of lint cleaning

(Pfieffenberger and Crumley, 1961 and 1963; Towery and

Baker, 1979). Staple length is of great importance because

of its impact on cotton price (Anthony et al., 1982).

Significant differences in hand classer's staple length are

often difficult to detect (Griffin et al., 1970). U.S.D.A.

classing offices currently are better equipped to detect

length reduction since their recent conversion to instrument

testing. Instrument testing and Suter-Webb length arrays

have detected lint cleaner induced effects on length

characteristics such as increases in short fiber content and

mean length decrease.

Even though short fiber content and uniformity ratio

(expressed as a ratio of mean length to upper quartile

length) do not affect cotton price, they are important

considerations to the spinner. The effects of lint cleaning

on short fiber content and uniformity ratio may become even

more important when the textile industry adopts new spinning

technologies, such as air-jet spinning, which require a

length-uniform fiber. Dependence of the process on length

and length uniformity is expected because roller drafting is

involved and because wrapper fibers are depended upon to

bond the structure together and impart strength to the yarn

(Price, 1986).

2.3.4 Tensile Properties

The importance of fiber strength in processing became

more obvious when strength values were added to the cotton

10

classing operation in 1984. The mechanical action of lint

cleaning is not considered to affect fiber strength.

However, fiber strength can influence the effectiveness of

lint cleaning as evidenced by the need for moisture control

during ginning (Griffin, 1977). Low humidity levels lower

fiber strength and increase fiber breakage- Fiber strength

may account for variation in the amount of fiber length

degradation during lint cleaning (Sasser et al., 1976).

Elongation is a fiber tensile property that does not

appear to be affected by lint cleaning (Baker et al., 1984).

Since fiber strength has shown a tendency to affect lint

cleaning performance, the combined effect of strength and

elongation should also be examined. The importance of fiber

stress-strain behavior in processing may also apply to lint

cleaning.

2.3.5 Micronaire and Its Components

Micronaire is an indirect, air flow measurement of

specific fiber surface. Basic theory of fluid flow (Fowler

and Hertel, 1940) indicates that the air permeability of a

test specimen should vary inversely with the square of

specific surface. The effects of lint cleaning on

micronaire are not well understood and have been reported to

be insignificant. Micronaire has been favorably correlated

with the formation of neps during mechanical processing

(Pearson, 1944).

11

A detailed investigation shows that micronaire value

(X) is closely associated with the corresponding fiber

maturity and fineness by the following relation (Lord,

1981) :

MH = M^Hg = 3.86x2 + 18.16X + 13.

where M = maturity ratio.

H = average weight/length in millitex.

Hg = standard fineness (weight/length when M = 1).

i.e., linear density attained when fibers mature

fully.

The quadratic equation arises because of the curvilinear

relation of the original empirical calibration of the

Micronaire scale. Assessment of fiber cross section solely

on the basis of micronaire value is unsatisfactory because

higher maturity (M) and increased coarseness (Hg) can

operate independently to give higher micronaire values.

Also, either immaturity or pronounced intrinsic fineness can

lower micronaire (Griffith and Goodwin, 1981) .

In order to characterize cotton fibers with regard to

their behavior during mechanical processing, geometrical

features, such as cross sectional shape and area, should be

determined (Gilhaus, 1984). The maturity and fineness of

cotton may account for variations in behavior of cotton

during gin processing (Griffin et al., 1970). Baker et al.,

(1984) found that fine-fibered cottons tended to suffer less

damage during lint cleaning then coarse fibers. Centrifugal

12

forces and air currents present in mechanical rotating

cleaning systems have different effects on coarse and fine

fibers (Szaloki, 1977). In fact, fiber waste collected from

filters in spinning often have a higher micronaire than the

original sliver (Price, personal communication). Bogdan

(1954) reported that maturity seemed to be an important raw

fiber factor relating to neppiness. Separation of

micronaire of the cotton fibers into fineness and maturity

should help study the effects of these characteristics

concerning nep potential and lint cleaning performance.

2.3.6 Yarn Strength Estimate

Perhaps the best index to cotton quality is the

performance of the fibers during spinning at the mill.

Changes in measured fiber properties caused by lint cleaning

may be insignificant, but these small changes can severely

affect yarn quality (Cocke et al., 1977*-'-). Yarn strength

is expressed as the product of a yarn's hank strength in

pounds and cotton count (yarn size in number of 840 yard

hanks per pound). A yarn stength estimate can be derived

from an equation based on measured fiber properties. This

equation may show that detrimental effects of lint cleaning

on fiber length can be better compensated for by other fiber

properties in some cotton types.

13

2.4 Varietal Effects on Lint Cleani na The influence of varietal differences in ginning has

focused on dust levels (Bevilacqua, 1982). Dust levels are

more highly correlated with harvesting method and growth

location than with variety (Hersh et al., 1980). Evidence

indicates that other effects of variety may influence lint

cleaning. An attempt to develop a mathematical model for

seed and lint cleaning was not successful until varietal

differences were considered (Read and Kirk, 1978).

An interdisciplinary Belgian research group has

determined varietal differences in the force required to

separate the fiber from the seed. Since the force required

to pull the fiber from the seed can exceed the force

required to break fiber strength, some fiber breakage may

occur in saw ginning before lint cleaning (Goldfarb, 1966) .

Differences in fiber strength may account for variation

in the amount of fiber length reduction during ginning and

subsequent lint cleaning (Sasser et al., 1976).

2.5 General Comparison of Ginning Treatments

The four ginning treatments used in this study are:

roller ginned, saw ginned with no lint cleaning, saw ginned

with two lint cleanings, and saw ginned with aggressive,

carding type lint cleaning. The lint cleaner referred to

here is the Hollingsworth Cottonmaster developed by Cotton

Incorporated. This ginning treatment is referred to as the

14

Cottonmaster in the text to distinguish it from saw lint

cleaners. Roller gins are used primarily for ginning extra

long staple cotton (Baker and Griffin, 1984). The roller

gin uses a laminated canvas/rubber roller with a fixed and

a reciprocating knife, to pinch and pull fibers from the

seed (Alberson and Stredonsky, 1964). Roller ginned cotton

generally has more dust, longer mean length, less short

fiber and fewer neps than saw ginned cotton (Cocke et al.,

1977*2) ,

Saw gins remove fibers from the seed by pulling them

through narrow slots in a metal grid by means of a rotating

saw cylinder. The seeds are too large to pass through the

slots. Saw ginning is a more efficient method for short

staple, fuzzy seed cultivars than roller ginning. The

increased opening action of saw ginning allows less trash

to be retained but increases short fiber content and neps.

Saw lint cleaners discharge foreign matter from fiber

by a combination of centrifugal force and stripping action.

The foreign matter is collected and removed pneumatically.

Mechanically harvested cotton normally requires two stages

of lint cleaning. Excessive saw lint cleaning can decrease

bale weight to an extent not compensated for by grade

improvements. Batt weight, combing ratio, saw speed, feed

rate, and fiber moisture content are all factors that

influence the performance of a lint cleaner and its effect

15

on fiber quality (Griffin et al., 1970 and Mangialardi,

1974) .

The goal of removing objectionable foreign matter while

preserving the inherent qualities of the fiber has prompted

new developments in lint cleaning. The action of the

textile carding process seems to be less damaging to fibers

than saw lint cleaning. This may be attributable to the

higher capacity in ginning operations necessitated by volume

and economic efficiency. Employing carding principles in

lint cleaning may be expected to remove more short fiber, as

that is one of the functions of the card (Szaloki, 1977).

Based on previous research, more aggressive lint cleaning

would be expected to increase grade, but decrease length

while adding to short fiber content and neppiness.

16

0

Bale Weight

Lint Cleaner Stages

Fig. 1. Effect Of Lint Cleaners On Classer's Grade And Staple Length, And Bale Weight And Value*.

*Source: Cotton Ginner's Handbook Agricultural Handbook No. 503, 1977.

17

j Yam Strength

Yarn Appearance

Lint Cleaner Stages

Fig. 2. Effect Of Saw Lint Cleaners On Nep Count, Yam Strength And J^pearance.

*Source: Cotton Ginner's Handbook Agricultural Handbook No. 503, 1977.

CHAPTER 3

MATERIALS AND METHODS

3.1 Materials

Seven cotton samples, chosen for wide variation in

length, strength and fineness were used in this study. The

test cottons were produced during the 1984 crop year on the

TAES farm at Lubbock. The test plots were stripper

harvested and split into three replicates. The cultivars

used, their corresponding test number and a general

description appear in Table 1.

3.2 Ginning Preparation

The harvested cottons were processed through an airline

cleaner, two inclined cleaners, and two stick extractors

before ginning. Fiber moisture during processing ranged

from 5.8 to 11.8 percent. The ginning treatments, with

their identification numbers are:

1 - roller ginned

2 - saw ginned; no lint cleaning

3 - saw ginned; two saw lint cleanings

4 - saw ginned; carding-type aggressive cleaner (Cottonmaster)

18

19

3.3 Fiber Tests

All the lint samples were conditioned at standard

conditions of 65% relative humidity and 70° Fahrenheit.

Fiber tests were performed according to ASTM standards.

High Volume Instrument test results were obtained from the

Spinlab line. Fiber properties were also obtained from the

following individual instruments.

Non-lint content: Shirley Analyzer

Length Characteristics: Peyer AL-101

Strength and Elongation: Stelometer, 1/8" gauge length

Linear Density and Maturity: Shirley FMT; (sample preparation in

the Shirley Analyzer)

Nep Count: Visually assessed on 10 grains of

raw fiber by two operators

The fiber test results were an average of two readings by

independent examiners.

3.4 Design of the Experiment

The experiment was a randomized split-plot design with

cultivar as the main plot and ginning treatment as the sub

plot. Three replications of each cultivar were harvested

and each replication was split into four plots for the

different ginning treatments. Sources of variation and

degrees of freedom for variance analysis are represented in

Table 2.

20

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21

Table 2. Split Plot Analysis Of Variance.

Main plots (A) = Cotton Cultivar (1 through 7).

Sub plots (B) = Ginning Treatments (1 through 4)

Source of Degrees of Variation Freedom

Replications 2

Cultivars (A) 6

Error a (Rep X Cultivar) 12

Gin Treatment (B) 3

A X B 18

Error b il

Ttotal 83

CHAPTER 4

RESULTS

4.1 Fiber Test Results

4.1.1 Length Parameters

Fiber length tests were performed on the Fibrograph and

Suter-Webb comb sorter as well as the Peyer AL-101. The

results from all the test methods were highly correlated.

The full scale histogram provided by the Peyer AL-101

results gave information which improved assessment of fiber

length damage. For this reason, length results in Table 3

are from the Peyer AL-101 instrument.

4.1.2 Properties Affecting Nep Formation

The fiber properties of micronaire, fineness, maturity

and non-lint content have traditionally been considered to

be some of the properties which influence nep formation

in cotton. The test results of these properties are grouped

together in Table 4.


It is believed that tensile properties of fibers may be

important to resisting mechanical damage. The strength and

elongation results reported in Table 5 are those from the

Stelometer at 1/8" gage length for two reasons: (1) Foster

22

23

et al. (1983), reported that the Stelometer 1/8" gage

strength measurement correlates better with yarn strength

than the 0 gage Pressley measurement; and (2) strength

measurements from HVI lines could be biased because of the

wide range of lengths exhibited by the test cottons. The

point of rupture on the length array may have been different

for different cotton samples (Price and Lupton, 1984) .

Reported fiber strength is a measurement of fiber tenacity

(force per unit linear density) in grams per tex.

Estimated yarn strength is reported in Table 5 as a

matter of interest since spinning trials and yarn analyses

were impossible in this particular study because of small

sample size. The number reported is an estimate of yarn

count strength product based on a regression equation using

fiber properties determined by the Spinlab HVI line.

4.2 Analysis of Variance Between Gin Treatments

Duncan's Multiple Range Test was used to determine the

significance of changes that occurred in fiber properties

because of gin treatments.

4.2.1 Length Characteristics

Table 6 illustrates variation between varieties (main

plots) when ginning treatments are averaged. The parameter

of percent short fiber content by weight below .75 inches

instead of below .50 inches as shown in Table 3 was used

24

because of the phenomena shown in Figures 3 and 4. These

histograms show a redistribution of the proportion of

shorter fibers occurring at the 0.75 inch point despite

cultivar, original staple length and gin treatment. Table

7 summarizes gin treatment (sub-plot) effects.

Table 8 shows that gin treatment and cultivar had a

significant effect on all the length characteristics. The

gin treatment X cultivar interaction was significant only

for short fiber content and coefficient of variation.

Although longer fibers prevailed in the ginning treatments,

some cultivars may have exhibited a greater tendency to

break during ginning. A higher frequency of fiber breakage

would alter the original variation of length within the

cultivar.

The physical changes in roller ginned length properties

due to two saw lint cleaners and Cottonmaster cleaning are

listed in Table 9. Correlation coefficients between damage

and initial fiber properties will be evaluated in the

Discussion chapter.


The ranges and significant differences between cultivar

tensile properties are illustrated in Table 10. Although

there is a large variation of strengths represented in the

test cottons. Table 11 shows that lint cleaning has no

effect on strength. Estimated yarn strength is affected,

25

presumably due to the influence of other fiber properties

involved in the calculation.

Estimated yarn strength in Table 12 is the only tensile

property with a significant gin treatment X cultivar

interaction. Gin treatment had no significant effect on

strength or elongation, but some cultivars' spinning

performance may be less affected by ginning treatment than

others. This result reiterates the assumption that other

fiber properties, as well as strength, contribute to yarn

strength.

4.2.3 Effects on Fiber Properties

Cultivar differences in the geometric features of

fineness, maturity, and micronaire are listed in Table 13

along with non-lint content and nep content. Attempts to

derive relationships between nep formation and fiber

properties appear in the Discussion chapter. Table 14

illustrates the effects of the gin treatments on these fiber

properties.

Micronaire is affected by saw ginning but not by lint

cleaning. The two components of micronaire (as defined by

Lord (1981)) are fineness and maturity. The percentage of

mature fibers tends to increase with more lint cleaning

while average linear density decreases. The lint cleaner

seems to preferentially remove coarser and less mature

fibers. This offsetting effect is not reflected in

micronaire measurements.

26

The main purpose of lint cleaning is to remove foreign

matter from the cotton and Table 14 shows that non-lint

content decreases with more lint cleaning. The adverse

effects of mechanical manipulation are seen in the

significant increases in nep density in Table 14.

Table 15 shows some significant variations in cultivars

between replicates for micronaire and maturity. These

properties are highly dependent on weather and cultural

practices, while fineness, which is more cultivar dependent,

did not have a significant replicate X cultivar interaction.

The only significant gin treatment X cultivar interaction

in Table 15 is for non-lint content. The roller ginned

non-lint content represents the original amount of trash in

each cultivar. The roller ginned non-lint content for the

seven cultivars ranges from 7.2 to 13.0 percent. The

Cottonmaster non-lint content is similarly low (1.4 to 2.0%)

for all the cultivars. The cultivars with initially more

trash in them exhibit greater cleaning efficiency because

more trash is there to be removed. This accounts for why

some cultivars appear to clean better than others even

though the end result is virtually the same.

27

20

18 I ^ 16 t

'a 14 t

>. 12|

^ 10} <U

u p

p

8 6

4

2

0

I

1 25 .5 ,75 1.00 1.25

Fiber Length (inches)

Fig. 3. Change In Fiber Length Proportions Of Tamcot SP-21S After Two Lint Cleaners.

Before Cleaning

.-. . I : . . .:•. After Cleaning

28

20 T

^ 18

S 16-IS 14-.

CQ 12-.

§ 10 I o p & 4

P

•H

8

6

4

2

0 ria 5 .75 1.00 1.25 1.5 1.75 .25

Fiber Length (inches)

Fig. 4.- Change In Fiber Length Proportions Of NX-1 After Saw Ginning.

........,., ••. •:-V.- • V-:.''.

Roller Ginned

Saw Ginned

29

Test Cotton

TAMCOT SP 21S 1/(5/18/84)

TAMCOT SP 2IS (6/6/86)

STRIPPER 31A (5/18/84)


ACALA 1517E-2 (5/18/84)

NX-1 (5/18/84)

PIMA S-6 (5/18/84)

Gin Treatment

Roller Gin Saw Gin Stand TWO Lint Clnrs Cottonmaster

Roller Gin Saw Gin Stand TWO Lint Clnrs Cottonmaster

Roller Gin Saw Gin Stand TWo Lint Clnrs Cottonmaster





Upper Quartile Length (inches)

1.03 1.04 0.99 0.98

0.91 0.87 0.87 0.84

0.95 0.94 0.92 0.92

0.83 0.83 0.83 0.84

1.19 1.16 1.15 1.14

1.33 1.30 1.29 1.28

1.25 1.21 1.17 1.17

Mean Length (inches)

0.78 0.79 0.75 0.75

0.72 0.70 0.69 0.68

0.74 0.75 0.72 0.74

0.67 0.67 0.67 0.68

0.97 0.96 0.94 0.93

1.10 1.06 1.03 1.05

1.01 0.95 0.91 0.92

Short Fiber Content (% <.5")

23.3 22.9 25.7 23.5

22.3 23.0 24.9 27.6

21.9 18.6 22.9 19.6

25.6 24.1 25.5 22.8

7.4 6.7 8.8 8.0

4.1 6.4 8.9 5.5

8.7 12.4 15.0 13.4

Coefficient of

Variation (%)

40.4 40.7 41.1 39.3

35.8 34.4 35.6 35.9

37.1 34.7 37.9 34.5

33.9 33.3 34.1 32.5

30.3 29.1 31.0 30.1

28.2 31.4 33.6 29.9

32.6 35.5 37.3 36.1

1/ — Averages of three replications

2/ — Planting date.

1 B

30

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32

l^ble 5. Stelometer Strength And Elongation, Spinlab Estimated Count Strength Product Results.!/

Estimated

Test Cotton Gin Treatment Strength Elongation Strength (g/tex) {%) (CSP)

TAMCOT SP 21S -^(5/18/84)

TAMCOT SP 2 IS (6/6/84)



ACALA 1517E-2 (5/18/84)

NX-1 (5/18/84)

PIMA S-6 (5/18/84)



Roller Gin Saw Gin Stand TWo Lint Clnrs. Cottonmaster





19.8 20.4 20.9 20.5

21.5 19.0 19.2 18.6

19.6 20.1 19.3 19.4

19.2 19.0 18.8 18.8

26.6 25.8 27.0 26.6

32.4 33.6 32.4 33.4

31.4 31.8 32.4 30.7

7.9 7.5 7.6 7.6

7.3 7.5 7.8 7.7

6.5 6.3 6.6 6.6

6.7 6.6 6.5 6.3

6.8 6.4 6.1 6.4

7.7 7.6 7.2 7.3

6.8 6.6 6.8 6.9

2065 2154 2250 2247

2036 2159 2133 2121

2128 2169 2235 2221

2091 2104 2174 2201

2417 2447 2558 2518

2631 2844 2879 2872

2800 2700 2818 2850

— Averages of three replicates.

2/ — Planting date.

33

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CHAPTER 5

DISCUSSION

The before and after cleaning fiber properties verify

the general effects of lint cleaning cited in previous

literature.

5.1 Fiber Property Changes

Cleaned cotton had poorer length characteristics than

uncleaned cotton, but there were only very small differences

between roller and saw ginning and between the two cleaning

methods. The carding-type cleaner appeared to remove more

short fibers and improve the coefficient of variation.

Roller ginned samples had more non-lint content and the

least neps followed by saw ginning, lint cleaning, and

carding-type cleaning. Linear density tended to decrease

with additional cleaning, but maturity values increased.

The possibility of an impurity bias in the Fineness/Maturity

values was lessened by individualizing and randomizing the

fibers in the Shirley Analyzer prior to FMT testing.

5.2 Fiber Property Relationships to Damage

This study is concerned with fiber property

relationships concerning two types of fiber quality damage:

length array degradation and nep formation.

43

44

5.2.1 Fiber Length Damage

The change in percentage fibers (by weight) less than

0.75 inches was used to indicate fiber breakage. The

increases caused" by tandem lint cleaners and the

Cottonmaster in percentage fiber less than .75 inch averaged

over three replicates ranged from 2.8 to 6.1 percent. An

analysis of variance indicated that these results were not

significantly different. However, these increases were

correlated with initial fiber properties and the correlation

coefficients are presented in Table 16.

The gin treatments were split because of the different

effects of fiber properties on damage. Strength and

strength X elongation correlated inversely and well with

damage that was incurred in saw ginning. Damage that

occurred after the fiber had been pulled from the seed -- in

lint cleaning -- was more highly correlated to fineness.

Attempts to develop a simple relationship between

damage and tensile properties were unsuccessful, so the

effects of fineness were considered. The Upland cultivars

(1-5) followed a trend of increased breakage as "bundle

strength X fineness" decreased. Cultivars 6 and 7 followed

the same trend but at a different level. The breakage

characteristics of the biologically finer fibers appeared to

be inherently different from the coarser Upland types. The

regression developed supports this hypothesis. Increase in

45

fibers <.75 inch = 9.9 - .0018 STF + 3.2 TOC.

R2 = .82 (n=21).

"t" values: STF = 3.2 (p = .005).

TOC = 2.9 (p = .010) .

where:

STF = bundle strength X fineness.

TOC = type of cotton; 0 = Upland, 1 = NX-1 or Pima.

This regression is illustrated graphically in Figure 5.

The strength times fineness variable represents an attempt

to estimate single fiber strength as well as to include the

importance of fiber fineness as related to fiber damage.

5.2.2 Nep Formation

There were significant differences in nep level among

cultivars, but changes in nep level due to cleaning were not

correlated well with any fiber property. Table 17 also

shows correlation coefficients between initial fiber

properties and final nep level. Final nep level is

negatively correlated with maturity and micronaire but nep

formation may be more dependent on mechanical manipulation

than inherent fiber properties.

The best regression equation that could be developed to

explain final nep level included fineness, length, and

non-lint content:

Neps = 31.2 - .24 Fineness X UQL + 3.9 NL

R2 = .50 (n=21)

46

Non-lint content allows neps to be formed around a trash

nucleus.

The initial difference in nep level between cultivars

appears to be related to maturity and to neps composed of

immature fiber entanglements. Neps that form from an

increase in mechanical manipulation are not necessarily

composed of immature fibers. The debate on the nep problem

continues with new developments such as finding neps in the

cotton boll (Hebert, 1986) and the traditional correlations

of neps with micronaire are inconclusive.

47

X u c

•H in 5

5 •

4 ••

cn p

- H &H

c •H 0 cn 03 T QJ 0 p O C M

Y = 9 .9 - .0018 STF + 3.2 TOC

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

Strength X Fineness 1000

Fig. 5. Effects Of Fiber Parameters On Increases In Fibers < 0.75 Inch.

- Upland

0 = N'Xl or Pima

48

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49

Table 17. Correlation Coefficients Between Neps And Initial Fiber Properties. _^__

Change Final in Nep Neps Level

Strength .27 .04

Elongation .30 .28

S X E .20 .23

Fineness -.24 -.38

Maturity -.11 -.50*

Micronaire -.17 -.48*

UQL -.18 .02

*Signifleant at .05 probability level.

CHAPTER 6

CONCLUSIONS

1. Length decreases resulting from fiber breakage are

related to an estimate of single fiber strength

(tenacity X tex).

2. The potential for cotton to form neps is inversely

related to maturity level (immature fiber neps) and

directly related to non-lint content (trash nuclei neps)

Increase in neps due solely to lint cleaning is more

closely related to the type of mechanical manipulation

(carding or revolving saw) than to fiber properties.

3. Lint cleaning improves the average maturity level of

cotton, possibly by removing immature fibers. Removal

of coarse fibers decreases average linear density.

4. There are no significant differences between saw-type

and carding-type lint cleaners regarding fiber breakage.

Cottonmaster cleaned cottons have more neps, less

non-lint content and lower short fiber content.

50

LIST OF REFERENCES

Afzal, M. and Afzal, I., 1985. "Ginning in Pakistan". Textile Horizons. Volume 5, p. 11.

Alberson, D.M., and Stredonsky, V.L., 1964. Roller Ginning American-Egyptian Cotton in the Southwest. USDA Agricultural Handbook 257.

Anthony, S.W., Wesley, R.A. and Brown, L.G., 1982. Dynamic Programming Model of a Cotton Ginning System. Transactions of the American Society for Agricultural Engineers, p. 179.

Baker, R.V., Brashears, A.D. and Collins, J.R., 1984. Interactions of Cotton Plant and Fiber Characteristics with Mechanical Cleaning. USDA Annual Report.

Baker, R.V. and Griffin, A.C., 1984. "Ginning." Cotton. Agronomy Monograph No. 24, p. 397.

Bevilacqua, L. , 1982. "The Dust Problem in Cotton Spinning". International Textile Bulletin. Vol. 3, p. 258.

Bogdan, J.F. 1954. "Nepping Potential of Cotton". Textile Research Journal. Vol. 24, p. 491.

Cocke, J.B., Bragg, C.K. and Kirk, I.W. 1977. Influence of Gin and Lint Cleaner Combinations and Mill Cleaning on Dust Levels and Yarn Quality of Acala Cotton. USDA Marketing Research Report No. 1064, p. 10.

Cocke, J.B., Kirk, I.W. and Wesley, R.A., 1977. Spinning Performance and Yarn Quality as Influenced by Harvesting, Ginning, and Mill Processing Methods. USDA-ARS Marketing Research Report No. 1066.

Cook, J.G. 1984. Handbook of Textile Fibers. Morrow Publishing Company. Durham, England.

Foster, E.R., Price, J.B., Whitt, R.E., 1983. "The Characteristics of Known Varieties of Cotton in Terms of Spinning Performance". Annual Report to the Natural Fibers and Food Protein Commision of Texas.

51

52

Gilhaus, K.F., 1984. "Analysis Techniques for Cotton '^leaning. International Textile Bulletin. p. 271.

''°^bv^??;n?'''" il^^: Cotton Fiber Properties as Affected by Ginning. Thesis, Georgia Institute of Technology.

'' ?QAo' * •.A "^^old, E., Andrews, F.R., and Griffin, A.C. lyb^. Drying and Cleaning Effects on Cotton Fiber Properties'. The Cotton Gin and Oil Mill Press. 63(15): Volume 7. ' ' —

Griffin, A.C. 1977. "Cotton Moisture Control." Cotton Gmners Handbook. USDA-ARS Agricultural Handbook 50 3, p. 13.

^^^^^i"' A . C , LaFerney, P.E. and Shanklin, H.E. , 1970. Effects of Lint-Cleaner Operating Parameters on Cotton Quality. USDA Marketing Research Report No. 864, p. 10.

Griffith, H.W. and P.E. Goodwin, 1981. Modern Methods for Testing Cotton Fiber Maturity. Shirley Developments Limited. Manchester, England, p. 37.

Hebert, J.J. 1986. The Anatomy of a Nep. Paper presented at the 1986 Beltwide Cotton Production Technical Conferences, Las Vegas, Nevada.

Hersh, S.P., Hobby, C.K., Fornes, R.E. and Batra, S.K., 1980 "The Effect of Cotton Grade, Variety and Growing Location on the Dust Generated in a Model Card Room". Textile Research Journal. Volume 50, No. 9, p. 539.

Leonard, C.G., Ross, J.E., and Mullikin, R.A., 1970. Moisture Conditioning of Seed Cotton in Ginning as Related to Fiber Quality and Spinning Performance. USDA Research Report 859, p. 16.

Looney, Z.M., LaPlue, L.D., Wilmot, C.A., 1963. Multiple Lint Cleaning at Cotton Gins. USDA Market Research Report 601, p. 53.

Lord, E., 1981. The Origin and Assessment of Cotton Fibre Maturity. International Institute for Cotton. Manchester, England, p- 15.

Mangialardi, G.J., 1970. Saw-Cylinder Lint Cleaning at Cotton Gins. USDA Technical Bulletin 1418, p. 73.

Mangialardi, G.J., 1974. Maximum Loading of a Lint Cleaner for Efficient Cleaning and Optimum Cotton Quality USDA Production Report No. 175, p. 5.

53

Mangialardi, G.J., 1979. "Lint Cleaning Efficiency at Gins and Its Significance". Textile Research Jounal. Textile Research Institute, Vol. 49, p. 479.

Mangialardi, G.J., 1980. Selecting Multiple Lint Cleanings to Maximize Cotton Bale Values. USDA Report to the American Society for Agricultural Engineers, p. 4.

Moore, V.P., 1977. "Development of the Saw Gin." Cotton Gmners Handbook. USDA, ARS. Washington, D.C., p. 1.

Pearson, N.L., 1944. Neps in Cotton Yarns as Related to Variety Location and Season of Growth. USDA Technical Bulletin No. 878. ~"

Pendleton, A.M., and Moore, V.P. 1967. Ginning Cotton to Preserve Fiber Quality. USDA Extension Service Report ESC-560, pg. 19.

Pfieffenberger, G. and Crumley, B., 1961 and 1963. The Effects of Different Ginning Treatments on Grade, Staple, Price, Fiber Properties, and Spinning Performance of High Plains Cotton. Reports to the Cotton Research Committee of Texas. Textile Research Laboratory.

Price, J.B. , 1984. "An Assessment of the Requirements for Texas Cottons to be Suitable for the Production of 100% Cotton Knitting Yarn at High Rotor Speed." Annual Report to the Natural Fibers and Food Protein Commission of Texas, Vol. 2, p. 37.

Price, J.B. 1986. Future Requirements for Modern Spinning Technology. Paper presented at the Texas Seed Trade Association (Cotton Division) Production and Research Conference. Dallas, Texas, p. 4.

Price, J.B. and Lupton, C.J. 1984. "Correlations Between Cotton Fiber Properties and Open-End and Ring-Spun Yarn Properties and Yarn Dyeability." Special Report to the Natural Fibers and Foot Protein Commission of Texas, p. 55.

Read, K.H. and Kirk, I.W., 1978. Mathematical Modeling of Seed Cotton and Lint Cleaning Systems. USDA Production Research Report No. 170, p. 3.

Rollins, M.L. 1949. "The Cotton Fiber". American Cotton Handbook, Volume 1. Ed. by D. Hamby. Interscience Publishers. New York.

54

Sasser, P.E., Jones, J.K. and Slater, G.A., 1976. Gin Cleaners Help Cotton Dust Problem in Textile Mills. Agro-Industrial Report. Cotton Incorporated. Volume 3, No. 3, p. 7.

St. Clair, J.S., and Roberts, A.L. 1958. Effects of Lint Cleaning of Cotton. USDA Market Research Report 238, p. 37.

Szaloki, Z.S. 1977. High Speed Carding and Continuous Card Feeding. The Institute of Textile Technology Series on Textile Processing. Textile Book Service. Plainfield, New Jersey.

Towery, J.D. and Baker, R.V., 1979. "Improving Gin Lint Cleaning for the Removal of Open-End Spinning Microdust. Textile Research Journal. Textile Research Institute. Vol. 49, p. 129.

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