SYNTHESIS OF POLYMER STRUCTURES FROM MESQUITE DERIVED FEEDSTOCKS

by

SHOU-JEN R. CHEN, B.S., M.S.

A THESIS

IN

CHEMICAL ENGINEERING

Submitted to the Graduate Faculty of Texas Tech University in

Partial Fulfillment of the Requirements for

the Degree of

MASTER OF SCIENCE

IN

CHEMICAL ENGINEERING

Approved

August, 1984

ii'~

n~

n-c. 'PrtJ

ACKNOWLEDGEMENTS

I want to express my thanks to my research advisor and

committee chairman, Dr. Richard W. Tack, for his assistance

and generous help. Special thanks to Dr. Uzi Mann for the

suggestions and serving as member of my committee.

I would like to extend my gratitude to my parents and

my beloved wife, Alice Chen; without their support, this de-

gree would have been impossible.

1 1

ABSTRACT

The ozonization of mesquite wood in the presence of 60

wt % water was studied. Due to the degration by ozone and

water, weight losses of 7 per cent of the original mesquite

mass were observed. Previous studies had indicated that

much of this weight loss was due to the destruction and so-

lubilization of the lignin fraction of the wood. Based on

the results of this study it was obvious that the ozone and

water created active functional groups on the water soluble

compounds which were formed. These groups were found to be

capable of initiating free radical polymerization of styrene

and forming copolymers with the styrene. These copolymers

were examined for molecular weight and thermal transition

properties. Thermal decompositon temperatures were shifted

upward by 10-20°c indicating a stiffening effect as the lig-

nin fragments were added to the polymer backbone. Also some

condensation polymers were produced based on paraformaldeh-

yde coupling of the lignin fragments. The longer parafor-

maldehyde bridges appeared to give the condensation polymers

better structural properties as adhesive binders.

l l l

TABLE OF CONTENTS

ACKNOWLEDGEMENTS 11

ABSTRACT 111

CHAPTER

I. INTRODUCTION 1

II. LITERATURE REVIEW 4

Chemistry and Structure of Wood Lignin 4 Reaction of Lignin with Ozone 6 Grafted Copolymerization of Oxidized Lignins

with Styrene 11 Tannin-Based Adhesive Synthesis from the Extract

of Mesquite 15

III. GENERAL DESCRIPTION OF EXPERIMENTAL METHODOLOGIES AND EQUIPMENT 18

Ozonation of Mesquite Lignin 18 Grafted Copolymer Synthesis 20 Adhesive Resin Synthesis 22

Resin Preparation 25 Preparation of Resin Adhesives 26 Manufacture of Particle Board 26 Testing 26

Equipment 27 Ozone Generator 27 Gel Permeation Chromatography 27 Differential Scanning Calorimeter 30 Thermoregulator System 30 Stirring System 31 Extraction of Ground Mesquite 31

IV. RESULTS AND DISCUSSION 33

Ozone Treatment of Mesquite Lignin Grafted Copolymer Synthesis

Ratio of Styrene and Dry Filtrate from Mesquite

Time Effect

1V

33 37

37 40

Effects of Suspension Agent 41 Comparison of Extracted and Non-extracted

Mesquite as a Starting Raw Material 45 Solution pH Effect In Polymerization 46 Study of the Mechanism of Copolymerization

Reaction 47 Adhesive Resin Synthesis 50

V. CONCLUSION 53

VI. SUGGESTIONS FOR FUTURE STUDY 55

Ozonation Process 55 Copolymerization 55 Adhesive Resin Preparation 56

LIST OF REFERENCES 57

APPENDIX

A. ILLUSTRATION OF LIGNIN DOUBLE BONDS REACTION WITH OZONE BY THE STRUCTURAL UNIT DERIVED FROM CONIFERYL ALCOHOL 59

B. GEL PERMEATION CHROMATOGRAPHY CALIBRATION CURVE 61

v

LIST OF FIGURES

1. Primary Precursors of Lignin 5

2. Schematic Formula for Spruce Wood Lignin by Freudenberg, with Modification by Harkin 7

3. Structure for Normal Conifer Wood Lignin, Based on Modifications of the Spruce Lignin Formulae by Freudenberg et al. 8

4. IR Spectra of the Original and Ozonized Lignin 10

5. NMR Spectra of the Original and Ozonized Methanol Lignin as Measured in d6-DMSO 12

6. The Effect of Original and Ozonized Lignin on the Polymerization of Styrene at 700c 14

7. Apparatus for Gas Phase Ozonalysis 19

8. Apparatus for Polymerization Reaction 21

9~ Soxhlet Extraction Apparatus 32

10. IR Spectra of Sample 13 36

11. TGA Results of P-7, P-lOAA, and P-13 44

12. The Reaction Scheme for Resin I and Resin II 51

Vl

LIST OF TABLES

1. The Copolymerization Reaction Conditions

2. The Operating Conditions of The Ozone Generator

3. Chromatographic System for GPC Analysis

4. The Effect of Ozone Attack on Mesquite Lignin

5. The Experimental Results of Grafted Copolymer Synthesis

v 11

23

28

29

34

38

CHAPTER I

INTRODUCTION

The central purpose of this research is to investigate

the possibility of using water extractable lignin compounds,

derived from ozonated mesquite biomass, as potential monomer

feed stocks. These monomers will be polymerized to produce

high moleclear weight resins, or they will be combinded with

commercial monomers to produce copolymers. The second phase

of the study will be directed at determining the properties

of the polymers and copolymers formed.

Mesquite trees are found on approximately 70 million

acres 1n the Southwestern United States and on the sandy

soil of plains and mesas of arid and semi-arid climates

(Little 1950; Record 1943). As such, mesquite represents a

rather dispersed biomass resource, but one, although harve­

stable by current technology. Even so, mesquite use 1s

still very limited (Dahl, 1982).

Among other things, mesquite waste-wood biomass has

been considered as a potential, low-grade feedstock for ru­

minant animals. The biomass derived from harvesting the

entire above-ground structure has been shown to have an in

vitro digestibility of only 26% (Tock,et al. 1982).

Investigations have shown that these low digestibility

1

2

levels can be largely attributed to the shielding effect of

the lignin fraction of the wood. If this barrier could be

removed, then the full holocellulose content(65% to 70% of

the moisture free tree mass, ~cott,et al., 1960) 1s poten­

tially available for conversion by the ruminant animal. Un­

forutunately, the removal of the shielding effects of the

lignin in wood is not easily accomplished.

One thermal-chemical process developed by the Depart­

ment of Chemical Engineering at Texas Tech University looks

attractive based on the quality of the feed produced. This

process treats the biomass with water and ozone. These rea­

gents combine to produce degradation of lignin by hydrolysis

and oxidation of the aldehyde, ketone, or alcohol groups.

After the aromatic ring structures have been opened, large

portions of the lignin material become solubilized and can

be removed (Kratzl, 1976). We will utilize this technology

to generate the monomer compounds which are to be used in

this study.

Based on the many studies of wood sturctures and their

degradation by hydrolysis and oxidation, we would expect

most of the monomer fractions derived from mesquite to

contain a high fraction of aromatic structures with short,

three to four carbon side chains. The ozone, as will be

shown later can create hydroperoxides which are free radical

3

formers, and hence free radical copolymerization or grafting

with polystyrene should be possible. Also, prior work has

shown that the aromatic structures which we will be generat­

ing can be used with formaldehyde to produce a condensation

polymer. These two reaction polymerization processes, free

radical and condensation, will therefore be studied during

this investigation.

CHAPTER II

LITERATURE REVIEW

Chemistry and Structure of Wood Lignin

The word "lignin" is derived from the Latin word "Lig-

num" meaning wood. Indeed, lignins form an essential campo-

nent of the woody stems of arborescent gymnosperms and ang­

iosperms in which the amount of ligin ranges from 15% to

36%. Lignins are not, however, restricted to arborescent

plants, but are found as integral cell wall constituents 1n

all vascular plants including the hervaceous varieties.

The exact definition and the differentiation of lignins

from other polyphenolic plant constituents remained a matter

of debate until the late 1960's. As the result of a gradual

clarification of ideas, a definition of lignins has finally

emerged to which most of the investigators in the field sub-

scribe. According to this definition, we understand lignins

to be polymeric natural products arising from an enzyme- in-

itiated dehydrogenative polymerzation of three alcohol pre-

cursors: (1) trans-coniferyl, (2) trans-sinapyl, and (3)

trans-p-coumaryl alcohol (Sarkanen, 1971) (Figure 1).

In 1964, Freudenberg (Freudenberg, 1964) made the first

ser1ous attempt to unify the available information on the

4

Ho@c H=CHCH{)f-1 I

OrVle

trans-Coniferyl alcohol

OMe ) \\

HOVCH=CHCHpH

OMe

trans-Sinapyl alcohol

HC) CH=CHCH20H

trans-p-Couf'lary l alcohol

Figure 1: Primary Precursors of Lignin

5

6

dehydrogenative polymerization of coniferyl alcohol together

with the combined analytical and reactivity data on spruce

lignin. The hypothetical formula for lignin which is repro­

duced in Figure 2. It represents an average fragment of a

larger lignin molecule and contains altogether twenty mono­

meric units. The majority of these are of the p-hydroxyphe­

nylpropane type, and one (unit 10), of the syringylpropane

type. While the Freudenbergian concept of lignin structure

has represented clearification, the more recent results in

dehydrogenative polymerization and structural studies are

already suggestive of some needed modifications. One modi­

fied structure is showm 1n Figure 3. The structure of

spruce lignin is probably representative of gymnosperm wood

lignins in general, and there is good reason to believe that

more or less analogous structural patterns are present in

all plant lignins.

Reaction of Lignin with Ozone

In recent years the reaction of ozone with lignin has

attracted considerable interest, mainly because the indus­

trial bleaching of chemical and mechanical pulps with ozone

produces waste effluents that are less hazardous to the

environment than the hyproducts produced by conventional

bleaching methods. To an organic chemist, the formulas in

b H.COH

-o\~X6;-a~

Figure 2:

CH::Q-C~OH

Schematic Formula for Spruce Wood Lignin by Freudenberg, with Modification by Harkin

7

Figure 3:

H~~~ (17') 0100

H{.;OH k H,COH

cbr-o\~~-fOAr(Ligl a..~&

',Q\ ~~HtfOH ~ HO<@,JO~'IH-:H-0~~ ,-

OM<z ~ o-4a CH

OAr(Li g)

8

Structure for Normal Conifer Wood Lignin, Based on Modifications of the Spruce Lignin Formulae by Freudenberg et al.

9

Figures 2 and 3 convey a clear idea of the difficulties

facing the investigator 1n structure research. It will be

noted that most of the monomeric units are linked together

by chemical bonds which are known to have a high degree of

stability. These include the C-C linkage, either of the bi­

phenyl type or of the alkyl-aryl type. Even the ether link-

ages, with the exception of the -aryl ether bond, are quite

resistant to degradation.

The presence of a large number of var1ous functional

groups and structural units in the lignin macromolecule sug-

gests that the ozonization of this polymer is a complex pro-

cess. The first fundamental information on this process was

elicited by compar1son of the changes 1n ultraviolet, 1n-

frared, NMR and ESR spectra. Katuscak et al. have published

the IR spectra of the original and ozonized lignin (Katus-

cak, et al. 1971). As shown in Figure 4, there is a lower

intensity of the absorption bands at 1530cm- 1 and 1612 cm-1

in the ozonized sample (curves 2 and 3). These wave num-

bers are characteristic of the C-H vibrations of the substi-

tuted benzene rings, and the reduced absorption 1s evidence

of the reaction of the ozone with the aromatic r1ng of

lignin. Similarly based on an increase of the carbonyl

groups absorption band at 1720-1750 it could be

assumed that the numbers of aldehyde groups or the increase

I t !

l I

11 ___ .......... :=-------

10

T (/.] 100

80

60

40

20 1 3

0 1500 1600 1100 '1800

~ [c.rn. J

Figure 4: IR Spectra of the Original and Ozonized Lignin

11

of stretching vibrations of the C=O groups associated with

carboxylic acids have increased.

NMR spectra of the original and ozonized samples are

shown in Figure 5. From these spectra, it can also be shown

that the aromatic rings were destroyed during the ozonation

process. Katuscak and the coworkers have concluded that the

reaction between lignin and ozone 1s demonstrated by the

destruction of aromatic rings of lignin. The degree of des-

truction depends on the medium in which the ozonization is

carried out and on the type of lignin used. Moreover, ozone

can also react with double bonds in the side-chain of phe-

nylpropane units, which are more reactive than the aromatic

rings (Hatakeyama, 1967). Ligin is reported to have one

double bond per 40-60 C9 monomer1c units (Tiscenko, 1959).

It is suggested that the reaction of lignin double bonds

with ozone proceeds according to the scheme of reaction

illustrated by the structural unit derived from coniferyl

alcohol (Appendix B).

Grafted Copolymerization of Oxidized Lignins with Styrene

One important method of modifying of macromolecules is

to introduce hydroperoxide groups at random positions along

the polymer chain to form a multifunctional initiator. The

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modification, or graft copolymerization, 1s brought about by

thermal or redox activation of the hydroperoxide groups 1n

the presence of a suitable monomer (Mikulasova, 1967).

Ozonization has been successfully used to peroxidize a

ser1es of aromatic and non-aromatic polymers. In 1972,

Katuscak publised a series of papers based on his finding

of using ozonization-generated, ligin free radicals in co-

polymerization reactions with styrene (Katuscak, 1971-1972).

In one of these studies, the kinetic curves (Figure 6) show

that the original lignins and also its diazomethane methy-

lated derivative exert a weak retarding effect on the poly-

merization of styrene. Ozonized lignins, in contrast to the

original lignins, are capable of accelerating the polymeri-

zatin of styrene after a certain inhibition period. The

ability of ozonized lignins to accelerate the polymerization

of styrene indicates that ozonized lignins can act as poly-

merization initiators.

Therefore, it was concluded that ozonization 1s a su1-

table method for preparing centers on the lignin macromole-

cules which may initiate grafting copolymerization reactions

with styrene. Also lignin as the macromolecular substance

composed of substituted phenolic units, exhibits a weak

inhibitory and retarding effect on free radical poly-

merization of styrene. Even by increasing the inhibitory

. : . ~

. . -

CO,\J \v' E R S ION [~]

1. pure styrene 2. styrene+ 10% lignin 3. styrene+ 10~6 ozonized 1 ignin_

10

5 l I 1 ---0

~r---0

~

_j 0 5 10 15

TJHE {HOURS}

14

Figure 6: The Effect of Original and Ozon6zed Lignin on the Polymerization of Styrene at 70 C

15

effect of lignin by its ozonization, after overcom1ng the

inhibition period, the polymerization of styrene will pro­

ceed at a markedly higher rate in the presence of ozonized

lignins than the thermal polymerization of pure styrene

(Katuscak, 1973).

Tannin-Based Adhesive Synthesis from the Extract of Mesquite

Tannin-based wood adhesives made by the base-catalyzed

polymerization of condensed tannins with formaldehyde have

been described as substitutes for synthetic phenolic resins

by different authors (Knowles and White, 1954). Most tannin-

adhesive resins previously reported had serious disadvantag-

es. These included poor strength, poor adhesion, brittle-

ness, impractical shelf-and potlives for the . res1n, long

pressing times, or short assembly times. Such disadvantages

have severely limited the industrial use of these resins.

The approach adopted for improving the strength proper­

ties of the lignin based resin to change crosslinking by ern-

playing reagents with longer molecules. The single methy-

lene bridges formed by formaldehyde were considered too

short to bridge over the longer distances such as those

found in the case of bulky tannin molecules. A factor that

might reduce the effectiveness of formaldehyde as a hardener

16

1s the immobilization of the tannin molecules by the first

methylene bridges formed so that large distances between

reactive points preclude any further crosslinking by short

methylene bridges.

The structure of the ma1n polymeric constituents of

tannin may be represented as follows:

OH

HO

This flavonoid unit may be repeated 2-11 times, with the

different units being linked 1n the following manner:

HO

• • • • • •

OH

OH

n=2 to 11

17

When tannins undergo reaction with formaldehyde to form

resins, tannin/formaldehyde condensates tend to have a low

degree of condensation resulting in bonds lacking strength

and water resistant. Small amounts of short-length phenol/

formadehyde, phenol/resorcinol/formaldehyde, and urea/for­

maldehyde polymer can be used to increase the degree of po­

lymerization of tannin/formaldehyde res1ns, decreasing

brittleness and increasing water resistance (Pizzi, 1978).

Furthermore, Pizzi's research efforts have indicated

that the improvement in the degree of polymerization, re­

sulted in tanin/formaldehyde resins which show better per­

formance adhesives. This suggests that the early immobili­

zation of the tannin/formaldehyde network by relatively few

methylene bridges was indeed the main cause of the brittle­

ness and poor water performance of simple tannin/ formadeh­

yde condensates,and not the high reactivity of the tannin

toward formadehyde.

CHAPTER III

GENERAL DESCRIPTION OF EXPERIMENTAL METHODOLOGIES AND EQUIPMENT

Ozonation of Mesquite Lignin

All mesquite samples subjected to ozone treatment were

Honey Mesquite harvested in the Lubbock, Texas area during

the summer of 1982. The mesquite was ground to 24-60 mesh

and stored 1n a plastic bag. The average lignin, cellulose,

and hemicellulose fractions were respectively 25%, 37%, 23%.

The remaining 15% consisted of crude protein and ash (Haw-

ley, 1926).

A schemetic of the ozonation apparatus is shown in Fig-

ure 7. A OREC 03Bl-AR ozonator was used to supply ozone in

all the experimental runs. The settings on the ozone gener-

ator were always maintained at the settings recommended by

the manufacturer. Under these conditions the ozone output

was a constant rate of 12.0 mg/Liter. The reaction vessel

used down stream from the generator was a U-shaped glass

container. One arm of the reactor had a fritted glass disc

on the bottom to support the ground mesquite. Previous

studies of lignin degradation with ozone had shown that

mesquite containing 60 wt% moisture gave the greatest degree

of conversion (Chang, 1981) . Therefore, all mesquite

18

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samples were presoaked with 60 wt% water, and kept in the

refrigerator for 24 hr before ozonation. In order to main­

tain this moisture level in the mesquite,it was necessary to

saturate the ozone-air stream. To do so, a 250 ml gas wash

bottle was connected between the onone generator and the in­

let of the U-shaped reactor. (next section)

Thirty to fifty grams of the moistened mesquite were

placed in the reactor each time and contacted with ozone for

a period of 2 hours. The ozone-treated mesquite samples

were then stirred with 200 ml of distilled water for 1 hour

at ambient temperature 1n a Erylenmeyer flask. The samples

were then filtered with a coarse fritted glass funnel. In

some experiments one half of the filtrate was air dried 1n

order to performed a mass balance calculation. The results

of the balances are reported in the results and discussion

section. In all cases, the filtrate was immediately trans­

ferred to a CSTR reactor for polymerization reaction stu­

dies.

Grafted Copolymer Synthesis

The apparatus diagram is shown in Figure 8. A 500 ml,

3-necks,

stirring

round bottom flask was

was provided us1ng

used as the reactor. The

a constant speed motor and a

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',

SPEE

D CO

NTRO

LLER

0 I ~~­

'((d)

t

A

! 0

I I

i

\beN

lri' J

~Ft

I'\.

) .._.

..

1 '

glass stirrer with a teflon stirring

reaction period, an inert gas (N2 or He)

the system at all times.

22

blade. During the

was purged through

Since the mesquite derived monomers were water soluble,

suspension polymerization was selected as the method whereby

the polymerization studies would be carried out. When the

styrene monomer was added, the mesquite monomer would dis­

trubute itself between the water and the organic phases.

Filtrate from the extraction of the ozonated mesquite (see

prev1ous section) was first added to the reactor. Styrene

monomer, benzoyl peroxide (initiator), and zinc oxide (sus-

pension agent) were then added slowly while the solution was

maintained under constant agitation at 70 rpm. The ratios

of the chemical reagents were dry filtrate : styrene : ben-

zoyl perozide : zinc oxide. These numerically were l:X;

0.002:0.02, with the amount of styrene monomer, X, being

varied. The solution pH effect, reaction time, and some

other effects were also investigated.

tions are listed in Table 1.

The reaction condi-

Adhesive Resin Synthesis

Tannins from mesquite were obtained by extraction of

the mesquite with hot water. Two methods were tried:

( ] )

( 2

) R

eact

ion

* T

ime(

h)

pH

P-7

18

1

0.0

P-8

9

9.5

P-9

18

10

.0

P-10

AA

21

.-

11 .

0

---P-

lOA

B

21

9.0

p-10

8 21

10

.0

P-1

2

23

10.0

TA

BL

E

1

The

C

op

oly

meri

zati

on

R

eacti

on

C

on

dit

ion

s

( 3)

**

( 4 )

In i

t i a

tor

~~ e

i g h t

o f

D

ry

(g)

Fil

trate

fro

m

i'1es

quite

(g

)

0.

15 ~

0. 1

~ 0

.82

0.15

0.

77

_,.....-

-

0. 1

5 /

) 0.

33

/

' ----

--~~-

0. 1

5 0.

33

0.

15

0.41

0. 1

5 0

.75

( 5 )

Sty

rene

Non

omer

(g

)

40

40

40

20

--------

20

20

20

'r )

(

. )

***

Sus

pens

ion

Rat

io o

f "

. "7

0

( '

... ~]ent,

'-n

g

, C

olum

n(5)

/Col

umn(

4)

1. 5

1.5

4

8.8

1.5

51.9

1.5

60.6

1. 5

60

.6

1.5

48

.8

1.5

26

.7

(Co

nti

nu

ed)

rv

w

TA

BL

E

l (C

on

tin

ued

)

P-13

P-15

A

P-15

B

P-16

_'--

k**

( 1 )

Rea

ctio

n T

ime(

h)

21

72

72

72

( 2 ) *

pH

10

.5

10

.0

2.0

2.0

(3)

**

In i

t i a

tor

( 9)

0.

l ~

0 0 0

( 4)

~·Jei g

ht

of

Dry

~-

i l t

rat

e f

flilll

H~squi t

e

(g)

1.15

1.08

0.9

6

0.9

1

( 5 )

Sty

rene

~1onomer

(g)

10

10

10 0

( 6 )

***

Sus

pens

ion

Age

nt,

ZnO

(g)

0 0 0 0

Rat

io o

f C

olum

n(5)

/Col

umn(

q

8.7

9.2

10

.4

* *"

***

pH w

as

adju

sted

wit

h co

ne.

NH40H

, si

nce

th

e o

rig

inal

oz

onat

ed m

esqu

ite

solu

tio

n

pH=2

.0

Init

iato

r w

as

benz

oyl

~eroxide.

Sus

pens

ion

agen

t w

as

Zin

c O

xide

. *

**

*

The

mon

omer

in

th

is e

xper

imen

t w

as d

-lll

€thy

l st

yre

ne.

-"' ~d· ·

;

',,~

_'i"

_t

eo • ~

tv

~

25

i) Soxhlet extraction for 72 hr.

ii) Magnetic stirring for 6 hr.

The extracted solution was filtered. Water was removed

by vacuum distilation. The dried residue was used as the

major constituent 1n the adhesive recipes described 1n the

next section.

Resin Preparation

Two different adhesive prepolymers were prepared.

Prepolymer l :

A mixture of 14.1 parts methanol, 25 parts of 99% pure re-

sorcinol was prepared at ambient temperature. To this mix-

ture 8.2 parts 38% formalin solution and 6.6 parts of 40%

aqueous sodium hydroxide solution were added still at am-

bient temperature. The mixture was brought to reflux and

held there for 1 hr, then cooled and stored.

Prepolymer II :

Mesquite tannins 14.7 parts, 30 parts of water was mixed at

ambient temperature. To this mixture, 8.4 parts of metha-

nol, 15 parts of 99% resorcinol, 5.0 parts of 38% formalin

solution and 4.0 parts of 40% aqueous sodium hydroxide

solution were added; still at ambient temperature. The

mixture was brought to reflux and held there for 1 hr, then

cooled and stored.

. .

26

Preparation of Resin Adhesives

All the res1ns were prepared in the following manner.

Enough of a 40% aqueous sodium hydroxide solution was added

to make the solution pH equal to 7~5. Then to 100 parts re­

sin, 14 parts of a 95% powder paraformadehyde were added.

Manufacture of Particle Board

Particle boards were prepared us1ng ground mesquite

mixed with the adhesive resins. Different ratios of ground

mesquite /glue mix were tried in order to obtain the best

composite. In all cases, the following procedures were fol-

lowed during fabrication:

Press Temperature: 1200c

Pressure: 350 atm

Pressing Time: 5 minutes

At the end of the pressing time, the heaters were turned

off, and the whole system was allowed to return to ambient

temperature before the particle board was removed from the

mold cavity.

Testing

The mechanical performance of the composite particle

boards are to be tested in the polymers laboratory. Each

particle board will be inspected for quality, water res1-

7 ..

27

sance, and strength of the board. However, a discussion of

the results obtained will not be a portion of this thesis.

Equipment

Ozone Generator

Ozone was gererated with a OREC 03Bl-AR ozonator, manu­

factured by Ozone Research and Equipment Corporation. The

operating conditions are listed in Table 2.

In all cases, the ozonator was allowed to come to equl­

librium for a minimum of 5 minutes before ozone was supplied

to the reactor.

Gel Permeation Chromatography

Molecular weight distributions of synthesized polymers

were determined by gel permeation chromatography (GPC). The

GPC was performed on a Waters Associates Model 244 high

pressure liquid chromatograph, which utilized Waters Associ-

ates -styragel columns. The specifications of the system

are listed in Table 3. In all cases, samples and molecular

weight standard solutions were prepared us1ng Tetrahydrofu-

ran (MCB, Omnisolv) as the solvent. All samples were

filtered wi~h a Waters Associates' Sample Clarification Kit.

TABLE 2

The Operating Conditions of The Ozone Generator

Cooling Water Pressure:

Compressor Pressure

Generator Pressure

Generator Amerage

[•1 a i n A i r F l ow

Rat? of Ozone Output

20 ps 1

40 ps1

15 ps1

4.25 amps

0. 45 CF~1

0.50 Ozone/day (12.0 mg/ Liter)

28

TABLE 3

Chromatographic System for GPC Analysis

G2l Permeation Chromatograph

Pump

CGlumn

Detector

i~obile Phase

Recorder

Wa-cers Associ .Jtes, Inc., ~~1 0 ci 2 l ~ 4 L~

vJaters ASSCJCiates, Inc.' ~odel M 6000A Solvent de·l i ve(y sys t::m

Waters Associates, Inc., 5~-styrage1 columns in

3 0 4 0

series: 10 A->10 A 5 0 6 0 0

->10 A->10 A-,100 A

~~ate r s Associ ate s , I n c . , Differential Refractometer

Tetrahydrofuran U·1C B, Omn is o l v) Flow rate: 2.0 ml/min Temperature: ambient

Houston Instrument Omni Scribe Recorder >lodel 85217-151

29

30

Differential Scanning Calorimeter

The synthesized polymer samples were also examined by a

Perkin-Elmer Model DSC-2C differential scanning calorimeter.

This instrument indicated pr1mary and secondary phase tran­

sactions such as melting points (Tm) and glass transition

temperatures (Tg). All the samples were recorded under the

same instrumental conditions:

Temperature Program: 3200K to 5500K

Heating Rate: 20°K/minute

Full Scale Range: 10 meal/sec.

Aluminum sample pans were used in all cases. The in-

strument was calibrated every week, using indium as a stan­

dard.

Thermoregulator System

Suspension polymerizations were carried out 1n a cons­

tant temperature environment consisting of two major compo­

nents and an oil bath.

1) Versa-Therm electronic temperature controller.

Cole-Parmer Instrument Co., Model 2149-2

2) Mercury Contact-Thermometer with moving-magnet.

,

31

Stirring System

Suspension of monomer was maintained with constant agi­

tation. This was accomplished with a Cole-Parmer Instrument

Co. Model 4651, which consist of two parts:

1) G. H, Heller Corp. Model GT21-18, constant speed,

dual-shaft stirrer.

2) G. H, Heller Corp. Model MTH-4, speed controller.

Extraction of Ground Mesquite

The ground mesquite biomass (24-60 mesh) was extracted

using a Soxhlet extraction apparatus (Figure 9).

The following routine was follow with each sample of

raw mesquite. The ground mesquite (30-40 grams) was weight­

ed into the glass extraction thimble of a continuous Soxhlet

extraction apparatus. Ethanol/Benzene (2/1) solvent mixture

was used for each extraction.

was for a period of 72 hou~s,

In all cases, the extraction

At the completion of the ex-

traction, the sample was removed from the apparatus and oven

dried for 24 hours.

32

-==;-~<i--[:RYING TUBE T TUBE-~r:;,( .·,.II . h ' - . h ( fl wit CcCI~J

L

COOLING WATER+-

+-COOLING \VATEP

THIHBLE

(,..-- ', ~<-ROUND BOTTOM E 0

SO LVEI'lT -> ---~~-:·: :: :.--.--J FLASK ---;? . / ,·

Figure 9: Soxhlet Extraction Apparatus

CHAPTER IV

RESULTS AND DISCUSSION

Ozone Treatment of Mesquite Lignin

Ozone has been shown to be an effective chemical rea­

gent for the degradation of lignin structure (Kiryushina,

1971). The effects of ozone attack on mesquite lignin in

this study were examined by carefully comparing the differ­

ences in weight loss for the ozonated mesquite sawdust ver­

sus non-ozonated mesquite sawdust. The results are tabulat­

ed in Table 4.

It is obvious that when the mesquite sample was ozonat­

ed, the weight loss after water extraction was greater than

the weight loss following water extraction of the non-ozo­

nated mesquite sample. The difference is probably due to

the additional amount of water extractable material which 1s

generated during the ozonation proess. Direct evidence can

be obtained by comparing the weight lost between samples 13A

and 13AA, since 13AA was derived from 13A. The 13AA sample

had been extracted by water before being submitted to ozona­

tion. Thus, essentially all the water extractable material

should have been lost. However, the additional weight lost

after ozonation provides a good indication of ozone lignin

degradation.

33

Sam

ple

No.

13

1 31\

* 13

AA

TABL

E 4

Th

e E

ffect

of

Ozo

ne

Att

ack

on

M

esq

uit

e L

ign

in

Bon

d dr

y M

esqu

ite

0 3 T

reat

men

t S

tart

ing

Wei

ght(

g)

16.3

2 +

18.1

2

16.3

0 +

Bon

d dr

.Y ~i

esqu

i te

a f

t e

r l~ a

tr? r

Ex

trac

tio

n( g

)

1-l.S

6

16.3

5

14

.33

Wei

ght

Los

t( g

)

1. 1

5

1.04

0.4

Hei

ght

Los

t(%

)

7.0

5. 7

2.9

Err

or

(%)

3.7

4.0

9.6

*S

amp

le

13A

A

is

the

der

ivat

ive

of

sam

ple

13A

. B

oth

sam

ple

13

and

13A

A w

ere

n1oi

sted

w

ith

60 wt~

of

wat

er b

efo

re o

zona

tion

.

w ~

35

Although extensive research have been performed

concerning ligin-ozone degradation in the past 30 years, a

complete data analysis of the water extractable ozonated­

lignin fraction has not yet been reported. In this study an

attempt was made to define the reaction products of ozoniza­

tion of lignin in more detail. Sample 13, after being vacu-

urn dried, was subjected to IR analysis. The IR spectra

(Figure 10) showed strong absorptions 1n the reg1on of

3750-2500 cm- 1 and 1700 cm- 1 This indicates the presence of

carboxylic functional groups. The NMR spectra, however,

does not reveal any additional information which could be

used to specify the constituents. This is probably due to

the fact that the sample is a very heterogeneous mixture.

Thus, a random, rather than a distinct proton absorption was

probably observed.

Kratzl has shown that ozone degradation of wood lignin

yields several classes of components with maJors fractions

being carboxylic acids, alcohols, ketones, and aldehydes

(Kratzl, 1976). Based on this report,several analytical ex-

periments were conducted in an attempt to obtained addition-

al information. However, due to the apparant complexity of

the sample mixture, none of these experiments gave any

significant results. Bearing the above-mentioned results 1n

mind, the assumption 1s warranted that the ozonization of

0

c

X .-~

I '-.i)

3JN~lllwSN88li.

0 0

,'1"

~ 10

lJ) ,.......

0 0 0 _.

0

~~ t 0: r, lJ) t: _.u

......

l 0 (/) l11a: ("

r~ o:J 1 0 z

0 w IN> ; <!.. ' :l +

0 a lfl (\)

0 a a (11

a a U1 (T)

a 0 (_J

OT

36

M ...-i

Q) ...-i 0.. E co Ul

~

0

co J-. +.J u Q)

0.. Ul

~ .,__.

•• 0 ...-i

Q)

J-. :::3 0'

• .-4

~

37

lignin is a complex and random process, leading not to a

simple, well defined reaction product mixture, but to a corn-

plex mixture of many different primary and secondary oxida-

tion products.

Grafted Copolymer Synthesis

The experimental results of grafted copolymer synthesis

are summarized in Table 5. The molecular weight of the co-

polymers were determined with GPC. By comparing the reten-

tion time of the sample with a standard calibration curve

(Appendix A), the molecular weight of each sample can be 1n-

terpolated. The glass transition temperature (Tg) of the

high molecular weight polymers were examined with DSC.

Ratio of Styrene and Dry Filtrate from Mesquite

The ratio of styrene monomer and dry filtrate from mes-

quite is defined by

weight of styrene monomer Ratio=

weight of dry filtrate from mesquite

Com

mer

cial

P

olys

tyre

ne

Pol

ysty

rene

P-

7

P-8

P-9

P-10

AA

P-10

AB

P-10

8

TAB

LE

5

The

E

xp

erim

enta

l R

esu

lts

of

Gra

fted

Co

po

lym

er S

yn

thesi

s

Rea

ctio

n T

ime(

h)

18 9 18

21

21

21

In i

t i a

tor

+ + + +

+ +

pH

10.0

9.5

10.0

11.0

9.0

10.0

0

Mol

ecul

ar W

eigh

t Tg

( K)

R

igid

ity

C

olor

150,

000

379

Rig

id

Bea

d W

hite

110,

000

343

Rig

id

Bea

d ~J

i1 i t

e ..

__

_ 5,00

0 S

tick

y Gu

m B

row

nish

G

rey

100,

000

382

Sof

t Gu

m L

ight

Br

mvn

100,

000

370

Rig

id

Bea

d L

ight

Yel

lo\'1

100,

000

372

Rig

id

Bea

d L i

g h

t Y

e 11

OltJ

90,0

00

370

Rig

id

Bea

d L

ight

Yel

low

{C

on

tin

ued

)

w

OJ

TA

BL

E

5 (C

on

tin

ued

)

Rea

c t·i

on

Tim

e (h

) In

itia

tor

pH

Mol

ecul

ar W

eigh

t

P-12

23

+

10

.0

90,0

00

* P-

13

21

+

10.5

50

,000

* P-

15A

72

-

10.0

70

,000

* P-

158

72

-2.

0 50

,000

**

P-16

72

-

2.0

* W

ithou

t Zn

O as

su

spen

sion

ag

ent.

**

d.

-met

hyl

styr

ene

vJas

us

ed

as

the

mon

omer

.

0

Tg(

I<)

354

375

, ·- 354

t '

375

Rig

idit

y

Ri g

·i d

Rig

id

Rig

id

Rig

id

Col

or

Brm

·Ji s

h G

rey

Brm

1i s

h G

rey

B I'C

J,Iin

13 rr

.:m

w

\0

40

In samples P-9 and P-12, where the ratio 1s decreased

from 51.9 to 26.7, the molecular weight did not show a great

change, only a polymer softness change was noticed. This

softness change might be expected, s1nce excess amount of

unreacted styrene may still be present. To prove that the

softness was 1n fact due to the unreacted monomer present,

some of the P-9 was subjected to a high vacuum device in

which the unreacted styrene could be removed. The resulting

polymer was indeed found to have hardened after 2 hours of

high vacuum.

Time Effect

Two experiments were performed 1n order to study the

time effect 1n the copolymerization reaction. Sample P-8

was the product of a 9 hr reaction time. GPC results showed

that the polymer produced during this time span had a mole-

cular weight of 5,000. The sample was also very sticky or

gummy. The strong odor of styrene could still be detected.

Thus, it seems reasonable to assume that the polymerization

process was not yet completed. Sample P-9 on the other

hand was allowed to reacted for 18 hr. It had a molecular

weight of approxrnentely 100,000. Although the polymer was

still soft in texture, it was apparant by drying that the

excess amount of styrene was the reason for the softness.

f: I• I '

c

J

41

Longer reaction times or higher reaction temperatures should

be able to 1ncrease the conversion. In this study, however,

no further attempts were made to enhance the degree of con-

version, since we were limited to a fixed pressure and temp-

erature during reflux.

Effects of Suspension Agent

The suspension agent (ZnO} was added 1n order to help

the monomer droplet rema1n well suspended in the aqueous so-

lution. Zinc oxid_e 1s a common suspension agent. It has

been used widely in polystyrene synthesis. However, .

ZlnC

oxide also seemed to have more than this one effect on the

particular polymerization system used.

In this study it also failed to show good suspens1on

capabilities. This was observed from the resulting bead

shape of the polymer mass. In only 40% of the experiments

performed was a uniform bead shaped copolymer formed, more­

over, when copolymer samples (P-8 to P-12) were dissolved in

tetrahydrofuran (THF), the solutions had a cloudy yellow co­

lor. After microfiltration in preparation for GPC analysis,

an interesting phenomenon was observed; the solution color

disappeared and the solutions became clear. It was also

noticed that the material collected on the filter surface

was colored. Judging from this behavior it was postulated

r I

that,

42

(1) either the copolymerization had not proceeded as

expected, and hence the color of the sample was merely be­

cause of a dyeing of pure polystyrene, or (2) that if the

copolymer was formed, then the colored portions of the po­

lymer were being adsorbed by solid particles (ZnO) when sam­

ples were dissolved in THF.

Several experiments were performed to study this ef-

feet. In one experiment the mesquite, after ozonation, was

extracted with water. To this filtrate, 5 grams of pure po­

lystyrene were added and the whole solution was kept agitat­

ed in the reactor at 100°c for 18 hr. After filtration, the

polystyrene were found to retain its white color while the

resulting solution had turned to dark brown.

sumption was therefore discard.

The first as-

If we consider that the second assumption was based on

the actual formation of copolymers, and that the colored

portions of the copolymer were adsorbed by the z1nc oxide

particle, then it would be necessary to prove that:

(i) A copolymer was formed.

(ii) Zinc oxide particles were the cause of polymer

decoloration due to selective adsorption of

the colored molecular species.

43

Partial proof of copolymer formation was obtained from

the DSC data. In addition, a thermo-gravimetric analy-

sis(TGA) 1 result, as shown in Figure 11, indicated that the

homogeneous polystyrene sample P-7 degraded at 3940c, while

under same condition, both copolymers P-10AA and P-13 de-

graded at 4140c These results provide strong evidence for

formation of copolymers. It indicates that the copolymers

are structure1y different from a homopolymer of polystyrene.

The 20°c shift upward in degradation temperature is probably

caused by the mesquite derived components being incorporated

into the backbone of the copolymers making them more heat

stable. In order to confirm that zinc oxide is the reason

for the filtered THF solution decoloration, a specific ex-

periment was conducted. Copolymer P-13 was synthesized by

keeping the same reactions condition, with the only differ­

ence being that no z1nc oxide was present in the system.

Some of the P-13 was then dissolved in THF and microfilter-

red. Unlike previous results, the filtrate solution main-

tained its color after filtration. Apparantly,the colored

fractions of the copolymer are sensitive to the presence of

zinc oxide. When no zinc oxide is present, these fractions

are once more mobile in the solution and pass through the

--------------------

1 The thermo-gravimetric analysis result was performed by the analytical laboratory of Cosden Chemical Company.

Wei

ght

Los

t(%

) lG

O%

80%

. :

60%

40%

I

20%

.J

t..U

;'G

l

100

<? ('

._j >__

.)>~

"

'~)

,. "

TGA

Co

nd

itio

n:

F~un

in

11

A

ir

11

40 °f

</r

n in

40

rn

m/m

in

Cha

rt S

pect

.. 10

0% F

ull

Scd1~

Deg

rada

tion

Tem

pera

ture

:

Pur

e P

oly

sty

ren

e[P

-7]:

39

4°C

·­

Gra

fted

Cop

olym

er[P

-lO

AA

,P-1

3]:

bl4°

C

i ---

·-· ·--:

-----j~--i· --

------

--~--

----·

' I I

----

----

~ --

--r-

. : __

, --

----

-

-~-----~-

--,--

1 I

I

I I <

I

-t l

'

l i

. l

r ---

-~-~--

( "r---

-t----

. l

~ j

200

i --

L --

Fig

ure

1

1:

TGA

R

esu

lts

of

P-7

, P

-10A

A,

and

P

-13

--

r/-/?

--

//

/I

I

-I

P-10

AA

I I l -

j I L

_

I

--i-

~-

1 !

I r t

. J

, I

I I

j !

I i

__

__

L

_

I ---··

·· ..

t l-

( 10

,:

)_

~ ~

45

filter. The reason for this phenomenon is not yet fully

understood and needs to be investigated in subsequent stu­

dies.

Comparison of Extracted and Non­extracted Mesquite as a Starting Raw

Material

It has been reported that ethanol : benzene=2 : 1 sol-

vent mixture is effective 1n extracting most of the organ1c

components from mesquite (Chen, 1981). In order to study

how these components affect copolymer synthesis, both ex-

tracted mesquite and non-extracted mesquite were used in ex-

periments as a starting raw material. In experiments lOAA,

lOAB, and lOB, the raw mesquite samples had all been ex-

tracted by the method discribed in the experimental section.

The characteristic of the resulting copolymers P-lOAA,

P-lOAB, and P-lOB are shown in Table 5.

It was found that when extracted mesquite was used as

a starting raw material, a pale yellow, elliptic shaped rlg­

id polymer bead would result. These copolymers all had high

molecular weights and rather constant Tg (370°K), even

though the reactions conditions (pH) were slightly varied.

on the other hand, when non-extracted mesquite (sample

P-12, P-13, P-15) samples were used, brownish: grey colored,

gummy materials were always formed. The suspension agent

46

seem to have lost its capability to maintain solution

suspension. The molecular weights were lower, and the Tg's

fluctuated in the range of 40°K The reason is still unk­

nown. Based on this evidence, however, it was reasonable to

conclude that those tractable components removed from mes­

quite prior to the ozonation process do play an important

role in subsequent polymerizations. Chen (Chen, 1981) had

reported that when ethanol/benzene solvent mixture was used

to extract mesquite, the extracted components probably con­

sisted of chlorophyll, a wide variety of fatty acids (wax­

es), and a considerable amount of phenolic tannin compounds.

Unfortunately, the exact compositions of these extracts were

too complicate to be analyzed with the equipment available.

Solution pH Effect In Polymerization

During the investigation, the pH value of the reaction

solution was found to effect the copolymer process. In an

effort to obtain more qualitative information on the pH ef-

fects, parallel experiments were conducted. Samples P-15A

and p-15B (Table 5) were synthesized without benzoyl perox-

ide as initiator. The P-15A solution pH was adjusted to

10.0 by NH40H and P-15B solution pH was unadjusted at

pH=2.0. It was observed that when no initiator was added,

the polymerization proceeded much slower. In the case of

47

P-15A, the yield was very low (<10%, based on styrene

weight) at the end of 72 hr reaction period. In P-15B case,

however, at the end of reaction period, more then 60% yield

(based on styrene weight) of copolymer were recovered. Al-

though the molecular weight of p-15B was found lower than

P-15A, the DSC data showed that P-15B had reacted more com-

pletely than P-15A. The exact reason for this behavior is

still unknown at this time. However~ this information would

appear to be valuable in studying reaction mechanism.

Study of the Mechanism of Copolymerization Reaction

A very important area of this research project was to

study the mechanism of the copolymerization reaction. It

was found from previous experience that this is an extremely

difficult task, since a total assay of the reaction products

of ozonization of lignin is unavailable, and the synthesized

copolymer analysis is also limited to examination of molecu­

lar weight distribution, glass transition temperature, and

some physical properties. It is not possible, therefore, to

propose a complete mechanism for the reaction process.

This problem of defining a reaction mechanism can be

clarified in part by reference to published results of

similar studies. In a study by Katuscak and the coworkers

48

(Katuscak et at., 1971-1973) it was suggested that during

the initial stages of ozonization of lignin, that functional

groups with active oxygen are formed. The functional groups

formed by oxidation with ozone are considered to be of hy­

droperoxidic character. Since lignin is of phenolic charac­

ter, neither the formation of quinoide functional groups nor

paramagnetic centres can be excluded. Along with the forma­

tion of presumed hydroperoxide groups, secondary reactions

leading to destruction, cross-linked and carbonyl products,

respectively, take place when oxidizing lignin. Their re­

search also proved that by using electron sp1n reasonance

spectrometry (ESR), the active oxygens formed were confirmed

to be stable free radicals, localized on the lignin macromo­

lecule.

A scheme of proposed general mechanism 1s reported as

follow:

Lig-H + 03 -----> Lig-0. + .OOH

Lig-0. + Lig-H -----> Lig-OH + Lig.

Lig. + 02 -----> Lig-00.

(Lignin hydroperoxide radical)

49

Lig-00. + Lig-H -----> Lig-OOH + Lig.

After heating, the ozonized derivative of lignin is ca­

pable of initiating homopolymerization of the styrene, as

well as grafted copolymerization of styrene with lignin:

Lig-OOH --A-> Lig-0. + .OH

n

Lig-0

The results presented and schematic reactions shown are

not intended to describe the complex mechanism of ozon1za-

tion of lignin and grafted copolymerization. They only de-

scribe the nature of theoretical assumptions. This is, how-

ever, a very valuable data base of information to future

research.

50

Adhesive Resin Synthesis

Since one of the purposes of this study was to ob­

tained preliminary information concerning the potential use

of mesquite tannin, only limited investigations on the a­

mount and effectiveness of these tannins were conducted.

The adhesive resin synthesis procedures presented here refer

to the published results of Pizzi (Pizzi, et at. 1978). The

reactions scheme for Resin I and Resin II are shown in Fig­

ure 12. It is obvious that the cross-linked structure should

provide better strength than most of the tannin-adhesive re­

Slns previously reported.

Both resins were found to set within 40 minutes in the

ambient temperature upon addition of paraformadehyde. The

resulting cross-linked adhesive polymers of these res1ns

have a reddish brown color, and both were highly water in­

soluble (no declaration was observed after being submerged

1n the water for 48 hr).

In making particle board, the best ratio of ground mes­

quite/glue mix appeared to be 55 parts of mesquite to 45

parts of glue mix. The particle boards prepared from Resin

I demonstrated resonable tensile strengths when submerged in

water for 72 hr, a slight decoloration of the water was

observed, indicating some unreacted solubles .

. ,..., ...

.'\ r--..

8.

HCHO

[a] +

HCHO 6 :O'QCH bJse r CH~\iy2

~10~0H n

--[RESIN I]

[TANNIN] [a]

OH

OH HO ~ l

OH /v"'~ OH ,CH? :

HO~OH- . [RESii~ II]

OH

Figure 12: The Reaction Scheme for Resin I and Resin II

51

OH

52

The particle boards prepared from tannin enriched Resin

II gave similar properties, except the color of the particle

boards fabricated were a more distinctive yellow color.

,

CHAPTER V

CONCLUSION

The degradation of lignin by ozone proved to be an

effective method. Based on the information accumulated, it

was found that about 7% of the mesquite tree mass was af­

fected by one ozone treatment. The 60 wt % moisture content

seems to be favored because it is just sufficient to swell

the woody structure, yet not provide a diffusion barrier for

the ozone or reaction products.

During the research period, attention has been focused

primarily upon the lignin radical/styrene copolymer synthe­

SlS. Effects of varying reactant ratio, reaction time, pH

value, and suspension agent were assessed. The reaction ra­

tio of styrene/dry filtrate from mesquite did not appear to

be a critical factor. Reaction time and pH value of the

reaction solution were both observed to affect the proper­

ties of synthesized copolymers greatly. It appeared that an

18 hours reaction time, and a solution of pH=2 can produce

satisfactory results. Studies also showed that ZnO is not a

suitable suspension agent for this reaction system, since it

apparantly produce some side effects on the copolymeriza­

tion.

53

-~·

54

The synthesized copolymers were all examined with GPC

and DSC. All the copolymers had high molecular weights.

The glass transition temperature, were less than 50°c higher

than the homogeneous polystyrene. The color of these copo­

lymers indicated that the ozonated lignin fragments are in­

volved in copolymer structures.

Although the mechanisms of the lignin ozonation and co­

polymerization are still not clear at this stage, Katuscak's

proposed mechanism seemed to be applicable to our system.

It provided an excellant suggestion for the direction of fu­

ture studied.

CHAPTER VI

SUGGESTIONS FOR FUTURE STUDY

Ozonation Process

At the present time, the efficiency of the ozonation

process is still low, the following possibilities are sug­

gested to increase the lignin degradation:

a) Pretreat the mesquite biomass with hydrochloric

acid (HCl) to remove cellulose and hemicellulose.

b) Use solution suspension ozonation instead of

pack-bed ozonation.

c) Supply oxygen to the ozonator instead of a1r. This L

should increase the ozone concentration tremendously.

Copolymerization

The most important part of future research should be

the study of the copolymerization mechanism. Several paten-

tial experiments can be performed:

a) Since ozonated lignin was assummed to contain free

radicals, a ESR spectra of the ozonated lignin

should provide distinct evidence.

b) Separation of the ozonated lignin fragments with

column chromatography, follow by NMR, IR examination

to identify the major components.

55

56

c) A kinetic study of the copolymerization reaction.

Compare the difference between ozonated lignin and

non-ozonated lignin toward styrene copolymerization.

d) To improve the quality of the copolymer, a reactor

that can sustain higher pressures is needed. At

higher temperature and higher pressures, greater

degrees of monomer convers1on can be achieved.

Adhesive Resin Preparation

The difficulty of mass producing mesquite tannin 1s due

to lack of proper equipment. A large scale tannin extrac­

tion and drying process is needed. If ·this can be solved,

then a wide scope of investigation in particle board manu­

facture can be conducted.

LIST OF REFERENCES

Chang,J.,"Comparison Of Mesquite Thermal Chemical Trement For A Ruminant Ration," M.S. Thesis, Texas Tech University,Lubbock,Texas(l981).

Chen,R.S.,"Extraction Of Organic Chemicals From Mesquite," M.S. Thesis,Texas Tech University,Lubbock,Texas(1981).

Dahl, B. E., "Mesquite As A Rangeland Plant," Mesquite Utilization Symposium, Texas Tech University, Lubbock, Texas (1982).

Freudenberg K., Holzforschung, 18, p. 3 (1964).

Hatakeyama, M., Tonooka, T., Nakano, J., and Migita, N., J. Chern. Soc. Japan. Ynd. Chern., 70, p. 2348 (1967).

Hawley, L. F., and Wise, Louis E. The Chemistry Of Wood, American Chemical Society Monograph Series No. 28, The Chemical Catalog Company, Inc., New York, NY (1926).

~ Katuscak, S., Hrivik, A., and Mahdalik, M., "Ozonization Of Lignin. Part I. Activation Of Lignin With Ozone," Papper och Tra, 9, p. 519 (1971).

v

(~ l/

v

v

Katuscak, S., Rybarik, I., Paulinyova, E., and Mahdalik, M., "Ozonization Of Lignin. Part II. Investigation Of Changes In The Structure Of Methanol Lignin During Ozonization," Papper och Tra, 11, p. 665 (1971).

Katuscak, S., Hrivik, A., and Macak., K., "Ozonization Of Lignin. III. Stable Free Radicals In Ozonized Lignin Preparations," Papper och Tra, 4a, p. 201, (1972).

Katuscak, S., Hrivik, A., Katuscakova, G., and Schiess!, 0. "Ozonization Of Lignin. IV. The Course Of Ozonization Of Insoluble Lignins," Papper och Tra, 12, p. 861 (1972).

Katuscak, S., and Mahdalik, M., "Modification Of Oxidized Lignins With Styrene," J. Applied Polymer Science, 17, p. 1919 (1073).

Kiryushina, M. F., and Tishchenko, D. v., "Ozonization Of wood As A Method Of Studying The Nature Of Chemical Bonding Between Lignin And Carbohydrates," J. App. Chern. USSR. 4 4 ( 1) , p. 15 0 ( 19 71) .

57

Knowles, E., and White, T., "Tannin Extracts As Raw Materials For The Adhesives And Resins Industries," Ad he s i v e & Res i n , 2 ( nos . 1 0 and 11 ) , ( 1 9 54 ) .

58

Kratzl, K., Claus, P., and Reichel, G., "Reaction Of Lignin And Lignin Model Compounds With Ozone," Tappi, 59(11), p. 86 (1976).

Little, E. L. Jr., "Southern Tress: A Guide To The Native Species Of New Mexico And Arizona," Agr. Handbook, No. 9, U.S.D.A. Forest Service. U.S. Govt. Print. Off. p. 65-67 ( 1950).

Mbachu, R. A. D., and Manley, R., "Degradation Of Lignin By 03, I.," J. Polymer Science, Polymer Chemistry Ed., 19(5/8), p. 2053 (1981).

Mikulasova, D., Makromolekulova Chemis, Chemicka Fakulta SVST, Bratislava (1967).

Pizzi, A., and Scharfetter, H. 0., "The Chemistry And Development Of Tannin-Based Adhesives For Exterior Plywood," J. Applied Polymer Science, 22, p. 1745 (1978).

Pizzi, A., and Raux, D. G., "The Chemistry And Development Of Tannin-Based Weather-And Boil-Proof Cold-Setting And Fast-Setting Adhesives For Wood," J. Applied Polymer Science, 22, p. 1945 (1978).

Record, S. J., and Hess, R. w., Timbers Of The New World. Yale University Press, New Haven, Conn. p. 640 (1943).

~ , tl4 ~ Sarkanen, K.V., and Ludwig, C. H., Lignins Occurrence, L- Formation, Structure And Reactions. Wiley-Interscience,

p. i. (1971). . LJ. 7/

Scott, R. w., Millett, M.A., and Hajny, W., "Wood Wastes For Animal Feeding," Forest Products Journal, 19(4), p. 14-18 (1969).

Tack, R. W., et al., "Ruminant Rations From Mesquite Biomass Pretreated With Water And Ozone," I & EC Prod. Res. & Dev., 21, p. 101-106 (1982).

--- · ··~""~'"" •. L¥!4£ W ~~,----

APPENDIX A

ILLUSTRATION OF LIGNIN DOUBLE BONDS REACTION WITH OZONE BY THE

STRUCTURAL UNIT DERIVED FROM CONIFERYL ALCOHOL

59

FREE RADICALS

CH20H I CH-0+ I CH-oo-

OCH3 OH

60

F'

APPENDIX B

GEL PERMEATION CHROMATOGRAPHY CALIBRATION CURVE

61

MW

10~

•

-

10~ •

GEL PERME~TION CHROMATOGRAPHY CALIBRATION CURVE

= ==

----

r--

------­..

--

t ·-t=. ..

--------- -- :_ -- -

: .. t

:=

-~-I 1..

~~!:::I !:

500 ~690

200'J

\

1=-" ~~ i: 50000 110000 233000 470000 _90COOO

:L_ ,_-::; :_,--:_

~'"' ' .:: ~ .... ~: _:_ ,l.:;.l,,:~ . ;c.;:_~ ~;::x~ ·c= :~ .. : =--

L"----- ---- ~-·

---~·--- -· ~~-t----

'"'~~=· ==---:· _I;~i.:_·:.,­-==-c'{O.:,:. • ;:i· .::-.=-~~'

·-'--~ ;~-,=:=-c~'-'0~

::::-::'\, -= c-=-c:. -:==: .. ~~

'-"F!;:...'-7 ~?=~·~'~ ;J....::h_::- :.c;:2io'= :.!:ic~£.:'Z. :.~-~- :i'~ -~ :..:~=-~~ ~~ ~± .;.-~ ~~"- \.~~ :=: 'c=c

-.· ~ :-- ~ 0: ,·_~c \ .;:::'"' -=o·0

.==::~_k -:=== ==-~ -~--:-=~~~~' ~~- .:_'-- :\ .=:= c:. :.:: ~-= ·::· - = j'- =- .,.. c:-=c·\·---·--= :

~------=~~ = -' - ,_- - :- .--:-~-.=-~~~-==-~-I--~-----~.-:- ... __ .-.!_--~- _·_f:.- ··•

-- ·i -:- - :----; --_--_--

62

\