Synthesis and Characterization of Phenol

Formaldehyde Resol Resins from Bark

Extractives by Autoclave

Yong Zhao+, Ning Yan+, Martin Feng++

+ University of Toronto ++ FPInnovation

Introduction

Objectives

Methodologies

Key Results

Conclusions

Outline

2

• PF resin industry valued at

approx. $ 2.3 billion in North

America, $10 billion in the

world (in 2010).

• PF resins has been widely

used in molding, insulation,

construction, electronic

devices.

Phenol Formaldehyde Resin

Introduction

3

Resol: pH>7, F/P>1.5

OH-

3D structure after curing

• Depletion of fossil fuel

• Carbon footprint

• Rising price of petroleum -

based phenol

Introduction (cont’d)

Environmental Concerns

Using renewable biomass materials as feedstock could

be a solution. 5

Introduction (cont’d)

Bark is rich in phenolic compounds.

Bark Materials

6

Introduction (cont’d)

Mountain Pine Beetle Infestation (MPB, Dendroctonus

ponderosae Hopkins)

• MPB affected approximately 10 million hectares of pine

forests in 2007 in western Canada

• Lodgepole pine (Pinus contorta)

Value-added applications of beetle infested lodgepole pine bark is highly

advantageous for the forest industry. 7

8

• Reactivity of phenolic compounds from biomass materials

towards formaldehyde and their adhesive application have

been demonstrated in previous studies.

• Phenol liquefaction or alkaline extraction: moderate

conditions, high yield...

• Autoclave extraction: chemical elements in soil, water

soluble vitamin in milk, autoclave/water to extract tannins

from bark……

…However,

• Very few studies on alkaline extraction of MPB bark with

autoclave.

• Resin performance (Curing, thermal stability and bonding

strength)

Adhesive Application of Biomass

Objectives

1. To obtain phenol substitutes from mountain pine beetle

infested lodgepole pine (MPB) bark through autoclave

extraction in alkaline solution.

2. To formulate bio-based bark extractive-PF resol resins

and to investigate the resin properties.

9

Mountain pine beetle infested lodgepole pine Bark

Bark Extractives

(Dried under either alkaline or neutral

condition)

Resin formulation (BEA-PF, BEA-PF(N),

30%, 50% and 70% phenol replacement)

and characterization (Curing behavior

& Bond Strength)

Bark Extraction (Autoclave, 120°C, 30min,

solvent/bark ratio = 5:1 (V/m))

Separation

O

OH

OHHO

OH

O

OH

OHHO

OH

O

OHOH

HO

OH

O

OH

OHHO

OH

Methodologies

Key results

Mn (Da) Mw (Da) Mw/Mn Stiasny number

(%)

Alkaline Extractives (wet) 1.46×103 2.45×103 1.67 -

Alkaline Extractives (dry) 1.07×103 1.96×103 1.83 43.11 (37.93)

Neutralized Extractives

(wet) 1.66×103 3.01×103 1.81 -

Neutralized Extractives

(dry) 2.53×103 5.85×103 2.31 42.96 (37.50)

Properties of bark alkaline extractives

Bark alkaline extraction by autoclave

Neutralization affected molecular weight of the extractives , but did not

affect extractives’ reactivity towards formaldehyde.

Average yield of extractives = 55.32%

Extraction condition: Autoclave 120°C, 30min, solvent/bark ratio = 5:1 (V/m), 1% NaOH

Bark alkaline extractives from autoclave extraction

Extraction condition: 100°C, 120min, solvent/bark ratio = 5:1 (V/m), 1% NaOH

13

• Bark alkaline extractives obtained using or without

using autoclave extraction contained tannin,

degraded lignin and degraded hemicellulose in their

composition.

• The tannin structures of the bark extractives were

mainly procyanidin type, consisted of phloroglucinol

A-ring, catechol B-ring and pyrogallol B-ring.

• Less C4-C8 and C4-C6 interflavonoid bonds, more

degraded lignin fragments and degraded

hemicellulose were found in the bark extractives

obtained using autoclave.

pH

Solids

content

(%)

Viscosity

at

25℃(cps)

Gel

time at

120℃

(s)

Mn (Da) Mw (Da) Mw/M

n

30% BEA-PF 12.42 50.91 440 78 481.6 960.5 1.99

50% BEA-PF 11.74 48.53 370 89 452.8 1132.2 2.50

70% BEA-PF 11.25 50.84 325 105 557.8 1243.8 2.23

30% BEA-PF (N) 12.11 48.81 580 59 801.2 1261.4 1.57

50% BEA-PF (N) 11.90 48.72 520 67 905.1 1385.9 1.53

70% BEA-PF (N) 10.91 47.98 495 88 698.4 1337.4 1.91

Lab PF 11.93 48.87 25 173 258.95 327.27 1.25

Com PF 11.16 59.00 200 172 212.09 386.48 1.82

Properties of the bark extractive-PF resins

Key results

Bark extractive-PF resin had a higher viscosity, shorter gel time, and higher Mw.

Dynamic DSC of bark extractive-PF resin (30% phenol

substitution rate)

Two exothermic peaks were observed in bark extractive-PF resins with 30%

phenol substitution rate.

Cure temperature of bark extractive-PF resins with

30% phenol substitution rate

30 BEA-PF 30 BEA-PF (N)

Heating

rate

(°C/min)

Onset

(°C)

Peak 1

(°C)

Peak 2

(°C)

Onset

(°C)

Peak 1

(°C)

Peak 2

(°C)

0 100.6 104.4 132.1 99.3 104.0 131.7

5 102.1 108.3 137.6 103.3 108.7 138.6

10 111.9 118.3 151.7 110.0 117.6 151.1

15 113.8 122.9 158.1 114.0 123.9 159.8

20 114.8 126.1 162.7 118.0 127.1 165.0

Lab PF: Onset temp: 95°C, peak temperature: 136 °C

Commercial PF: Onset temp: 98°C, peak

temperature:127°C

Dynamic DSC of bark extractive-PF resin (50% phenol

substitution rate)

Single exothermic peak was observed in bark extractive-PF resins with 50%

phenol substitution rates.

Dynamic DSC of bark extractive-PF resin (70% phenol

substitution rate)

Single exothermic peak was observed in bark extractive-PF resins with 70%

phenol substitution rates.

50 BEA-PF 50 BEA-PF(N)

Heating rate

(°C/min)

Onset

(°C)

Peak

(°C)

Onset

(°C)

Peak

(°C)

0 111.5 115.8 117.4 122.2

5 117.2 121.5 121.5 126.2

10 121.9 128.4 124.0 132.5

15 129.1 134.4 127.7 136.1

20 133.2 140.0 132.3 140.5

70 BEA-PF 70 BEA-PF(N)

Heating rate

(°C/min)

Onset

(°C)

Peak

(°C)

Onset

(°C)

Peak

(°C)

0 123.7 128.6 132.4 142.3

5 127.5 133.0 135.6 145.9

10 133.5 139.8 137.1 149.1

15 137.4 146.1 139.8 152.1

20 141.1 148.5 143.5 156.2

Cure temperature of bark extractive-PF resins with

50% and 70% phenol substitution rate

Parameters of cure kinetics of different resins

E1

(kJ/mol)

A1

(/s)

E2

(kJ/mol)

A2

(/s)

30 BEA-PF 90.91 1.06X1012 74.15 7.05X108

30 BEA-PF(N) 87.76 3.76X1011 70.92 2.56X108

50 BEA-PF 95.17 1.59X1012 - -

50 BEA-PF(N) 128.44 3.29X1016 - -

70 BEA-PF 115.18 2.91X1014 - -

70 BEA-PF(N) 190.36 4.20X1023 - -

Lab PF 70.22 1.59X108 - -

Commercial PF 82.23 1.18X1010 - -

Bonding development of resins

DMA of bark extractive-PF resin (30% phenol substitution rate)

tanδ

Ttanδ

E’min

E’max

ΔE

Tgel

Tgel and T tanδ of the bark extractive-PF resins slightly decreased with

increasing phenol substitution rate in the resin formulation.

No significant difference was observed in the rigidity of resins made with 30%,

50% and 70% phenol substitution rates.

Thermal stability of cured resins

30 BEA-PF

(%)

50 BEA-PF

(%)

70 BEA-PF

(%)

Lab PF

(%)

Commercial PF

(%)

RT-200 13.12 10.17 11 11.62 13.83

200-400 17.82 23.45 28.96 10.31 22.64

400-600 13.03 11.85 9.82 14.53 15.91

600-700 2.57 2.33 1.36 2.49 2.41

Total 46.54 47.8 51.14 38.95 54.79

Bark extractive-PF resins made from autoclave bark extractives dried under

alkaline conditions

Bark extractive-PF resins made from autoclave bark extractives dried under

neutral conditions

30 BEA-PF(N)

(%)

50 BEA-PF(N)

(%)

70 BEA-PF(N)

(%)

Lab PF

(%)

Commercial PF

(%)

RT-200 17.75 8.63 12.13 11.62 13.83

200-400 17.08 27.05 26.94 10.31 22.64

400-600 11.71 11.38 10.24 14.53 15.91

600-700 3.36 2.09 1.64 2.49 2.41

Total 49.9 49.15 50.95 38.95 54.79

Bonding Strength of different resins S

he

ar

Str

en

gth

(M

pa

)

Bark extractive-PF resins with 30% phenol replacement by autoclave extractives dried

under alkaline condition and neutral condition, bark extractive-PF resin with 50% phenol

replacement by autoclave extractives dried under alkaline condition had comparable dry

and wet bonding strengths to the commercial PF.

Bark extractive-PF resins with 50% phenol replacement by autoclave extractives dried

under neutral condition exhibited similar dry and wet bonding strengths to the lab PF

resin.

Neutralization negatively affected the bonding strength of the BEPF resins when the

phenol replacement was higher than 50%.

Conclusions

• Bark alkaline extractives obtained from autoclave extraction

contained tannin, degraded lignin and degraded

hemicellulose in their composition. It had less C4-C8 and C4-

C6 interflavonoid bonds, more degraded lignin fragments

and degraded hemicellulose than that of extractives obtained

from normal alkaline extraction .

• Bark extractive-PF resins had a higher Mw, higher viscosity

shorter gel time and faster curing rate than the lab PF resin.

• Neutralization of extractives before drying process affected

the extractives’ molecular weight, curing behavior and

bonding strength of the resulting bark extractive-PF resins.

• Bark alkaline extractives obtained from autoclave extractions

is suitable to replace petroleum-based phenol for PF resin

formulation.

Prof. Ning Yan & Martin Feng.

FP Innovation Forintek Division

Lab-mates for suggestions and discussions.

Acknowledgement

Acknowledgement

• Ontario Ministry of Economic Development and Innovation

30

• Industry partners

• Participating institutions

MINISTRY OF ECONOMIC DEVELOPMENT AND

INNOVATION

Thanks!

FTIR of extractives

1000 1500 2000 2500 3000 3500

Wavenumber cm-1

Tra

nsm

itta

nce

Bark autoclave extractives

dried under alkaline condition

Bark autoclave extractives

dried under neutral condition