Materials Sciences and Applications, 2012, 3, 151-156
http://dx.doi.org/10.4236/msa.2012.33023 Published Online March 2012 (http://www.SciRP.org/journal/msa) 151
Testing the Use of Coconut Fiber as a Cushioning Material
for Transport Packaging
Clívia D. Pinho da Costa Castro1, José de Assis Fonseca Faria1, Tiago Bassani Hellmeister Dantas2
1Faculty of Food Engineering, University of Campinas-UNICAMP, Campinas, Brazil; 2Centre for Packaging Technology-ITAL,
Campinas, Brazil.
Email: assis@fea.unicamp.br
Received December 21st, 2011; revised January 17th, 2012; accepted February 21st, 2012
ABSTRACT
In spite of being a raw material of virtually unlimited availability due to the massive consumption of the highly popular
coconut water, fiber produced from green coconut is much less used than the dried coconut fiber. The objective of this
study was to investigate the performance of green (white) coconut fiber as a cushioning material for use in packaging
systems. The mechanical performance of both green coconut fibers in their natural state as well as those molded into the
shape of cushioning pads were evaluated by shock absorption tests. The results showed that the fibers without aggluti-
nation agents exhibited the best performance when submitted to increasing static loads by presenting the greatest capac-
ity to reduce impact acceleration. In addition, green coconut fiber presented behavior similar to that of cellulosic cush-
ioning materials and in certain situations can be considered effective in protecting products that are considered fragile.
Keywords: Coconut Fiber; Impact; Cushioning
1. Introduction
Among vegetable fibers, coconut fiber (Cocos nucifera)
has been extensively used in the development of eco-
logical products, probably due to its characteristic as or-
ganic solid waste. Within this context, the traditional
making of ropes, brushes, carpets, mats, and more re-
cently, the manufacture of automotive components and
gardening products, all of which generally use the dried
fibers of mature coconut molded with vulcanized rubber.
However, large volumes of post-consumer white coconut
fibers pose enormous ecological problems—particularly
in large urban centers where they are generated as solid
waste by coconut water processing industries—and for
which, so far, only very few applications have been
evaluated. On the other hand, even being available in
huge quantities as a result of the increasing consumption
of coconut water, green (white) coconut fiber has not
established itself on the Brazilian market as a raw mate-
rial source. A recent survey estimated that in 2008 ap-
proximately 2.5 million metric tons of coconut husks
were generated in Brazil [1]. However, of the total
amount of coconuts harvested in the world, only 15% of
the fibers are put to good use [2].
The lack of knowledge concerning the properties of
white coconut fiber is the reason why it is much less used
compared to the mature coconut husk fiber [3]. For that
reason, a viable alternative would be the use of coconut
fiber as a protective material in packaging systems.
Though some studies do mention this possibility [4,5], no
research studies were found in the literature on the cush-
ioning properties of this material or of any other potential
applications.
In cushioning systems, the use of cellulosic materials
has been common practice for quite some time; however,
the preference for plastic materials in the cushioning
segment is related to the level of protection of the prod-
uct provided per amount of material and also by its resil-
ience properties. In a comparative study [6], concluded
that plastic materials provide better protection for a
smaller amount of material compared to non-plastic ma-
terials. Furthermore, plastic materials are not affected by
moisture, are decomposition-resistant and resist fungal
growth. However, ecological requirements have been
encouraging reducing the amounts of plastic materials
used in the manufacturing of packagings, as well as re-
search and development of alternative materials and
technologies. Within this context, based on the results of
mechanical tests, this study investigates the levels of
protection that can be provided by coconut fiber, both
when used in its natural form and as molded into cush-
ioning pads with the aid of natural agglutination agents.
2. Experimental
2.1. Material
The raw materials used were: 1) green coconut husk was
Copyright © 2012 SciRes. MSA
Testing the Use of Coconut Fiber as a Cushioning Material for Transport Packaging
152
used to obtain fibers; 2) natural agglutination agents were
used to shape and mold the coconut fibers pads.
The fibers were obtained by a mechanical de-husking
process of the husk coconut, which is a post-consumer
waste product after the extraction of coconut water, a
popular thirst quencher consumed in urban settings such
as kiosks and leisure areas located in the city of Campi-
nas, SP, Brazil.
For the manufacture of pads were used as agglutina-
tion the following agents: centrifuged natural rubber la-
tex, supplied by Braslátex Ind. e Com. de Borrachas Ltda,
Bálsamo-SP and cassava starch purchased from a local
retail outlet in Campinas, SP, Brazil.
2.2. Methods
2.2.1. Extraction of Coconut Fiber from the Fruit
Husk by Mechanical Defibration
After harvesting, the whole coconut husks were first
passed through a dry pre-cleaning process and then defi-
brated by a mechanical process, that is, without previous
crushing of the husks into fragments [7,8]. Basically, the
process use a rotating machine where the coconut husk
are exposed to high impact in order to disintegrate the
husk into fiber and dust. After disintegration the fibers
were separated from the coconut dust by using a rotary
sieve and subsequently sun dried to a final a moisture
content of 15%.
2.2.2. Evaluation of the Coconut Fiber
Whereas the aim of the defibration was to obtain long
fibers in order to obtain a better cushioning performance,
the length of one hundred individual fibers was measured
at room temperature 26˚C ± 2˚C by using a caliper with
accuracy of 1 mm [2].
2.2.3. Preparation of the Test Specimens of Coconut
Fiber
The coconut fibers were used to make test specimens that
subsequently were used for shock absorption testing.
Two types of test specimen were obtained: 1) fiber in
their natural way or without using any additive; 2) fiber
pads bonded with natural agglutination agents.
Test specimens of fiber pads without additive: consid-
ering the difficulty to determine the thickness of bulk
materials, it was decided to evaluate the materials as a
function of their weight and not based on the thickness,
as would be usual. Thus, test specimens with masses of
0.025 kg, 0.050 kg, 0.075 kg e 0.100 kg of fiber, were
weighed in a semi-analytical balance.
Test specimens of fiber pads with agglutination agents:
it was prepared by varying the thickness of the test
specimen (0.025 m and 0.050 m) and the type of agglu-
tination agent (latex and starch). All cushioning pads
were molded to the same mass (0.050 kg for 0.025 m and
0.100 kg for 0.050 m) and same shape of the test speci-
mens (0.2 × 0.2 mm). For this, the fibers were molded in
a cardboard box containing the dimensions of the test
specimen. During the preparation of the pads containing
agglutinant the latex was diluted with water up to a ratio
of 5% rubber solids. The agglutinants were sprayed onto
the fibers using a pneumatic pulverizer. The material was
deposited into a mold of suitable size and shape and the
resulting pads were dried in the sun during 30 minutes
followed by the removal of mold and dry the pads up to a
moisture content of 15%. For the pads with starch, the
gel was adjusted to contain 5% starch by heating with
water at 80˚C. As previously, the agglutinant was sprayed
onto the fibers, molded and dried in sun [7].
All test specimens were conditioned for 48 hours in a
room with conditioning atmosphere at 23˚C ± 1˚C e 50% ±
2% RH, until the time of impact test based on the princi-
ples and guidelines of ASTM Standard Test Method D
685 (1993).
2.2.4. Shock Absorption Test
The impact absorption capacity of the coconut fiber was
evaluated using a shock absorption test based on the
principles and guidelines of ASTM Standard Test Method
D 4168 (2002). In this test, wooden boards were used as
static load subjected to vertical free fall under the coco-
nut fibers pads in order to assess the ability of fiber to
slow the impact. The drop testing equipment used in-
cluded a MTS Model 868 Shock Absorber Test System,
a PCB model 8626M01 accelerometer, attached to the
shock absorber bench; a Dytran model 3105A acceler-
ometer, attached to wooden boards used as static load;
and a wooden box used as a support for the samples.
Signal analysis was performed with the GHI Wincat
sofware program (version 2.00), using a 500 Hz filter.
The tests were performed in two stages. In the first
stage, the test specimens consisting of coconut fibers
pads without additive; and in the second stage, test s-
pecimens consisting of coconut fibers pads with aggluti-
nation agents. All tests were conducted at room tem-
perature 21˚C ± 2˚C and relative humidity of 60% ± 3%.
To assess the performance of the natural coconut fiber,
the drop height was 0.30 m and the following variables
were selected: 1) Static pressure varying from 0.11 to
0.94 kPa, a range which falls into the category classified
as “light” [9]; 2) mass of test specimen varying from
0.025 to 0.100 kg. Under these conditions forty trials
were performed in triplicate, as planned in Table 1. After
these tests, evaluated the best points of the curve on the
level of protection and the tests were repeated for a drop
height standard of 0.75 m. Thus was possible estimate
the loss of thickness of each specimen immediately after
the shock absorption.
Copyright © 2012 SciRes. MSA
Testing the Use of Coconut Fiber as a Cushioning Material for Transport Packaging 153
To assess the performance of the coconut fiber pads
using agglutination agents, the other parameters were the
same as the previous plan, but only five values were ap-
plied static pressure, as shown in Table 2.
3. Results and Discussion
3.1. Evaluation of Coconut Fiber
The fact that the coconut husk did not have to be previ-
ously crushed, not only speeded up the defibration proc-
ess and made it more agile, it also produced a greater
proportion of long fibers, with an average length of 153 ±
49 mm. With the defibration process, white fibers are
obtained which turn brown during drying due to the ac-
tion of polyphenol oxidase. This enzyme is commonly
found in fruits and vegetables and promotes aerobic oxi-
dation of a variety of phenolic substrates [10]. Its action
resulted in the formation of brown fibers, due to the rup-
ture of tissue (husk) during defibration and contact with
ambient air during drying (Figure 1).
3.2. Shock Absorption Behavior of Coconut
Fiber Pad without Agglutinants
The results of the shock absorption test are presented in
Table 1. Planning of shock absorption test using coconut
fibers without agglutinants, as static pressure and mass of
test specimen.
Static (kPa)
Mass (kg) 0.11 0.18 0.28 0.38 0.48 0.55 0.65 0.74 0.84 0.94
0.025 1 2 3 4 5 6 7 8 9 10
0.050 11 12 13 14 15 16 17 18 19 20
0.075 21 22 23 24 25 26 27 28 29 30
0.100 31 32 33 34 35 36 37 38 39 40
Table 2. Planning of shock absorption test using coconut
fibers with agglutinants, as static pressure and thickness of
test specimen.
Static (kPa)
Thickness (m) 0.11 0.18 0.28 0.38 0.48
0.025 1 2 3 4 5
0.050 6 7 8 9 10
Figure 1. Coconut fiber after mechanical defibration.
the Figures 2 and 3, that is, deceleration peaks on the
vertical axis and static load on the horizontal axis. Fig-
ure 2 shows the behavior of natural coconut fiber using
test specimens of fiber pads without additive with four
different weights, static charge in the range from 0.11 to
0.94 kPa and drop height of 0.30 m. Under these condi-
tions, all curves showed an increase of slowing up with
increasing static load, except at the point of 0.55 kPa,
where there is a sharp drop of the slowdown in the four
test specimens. This behavior highlights best level of
protection compared to 0.55 kPa at higher loads, how-
ever would need further study load in less than 0.55 kPa.
Also in Figure 2, it was observed that after 0.65 kPa,
most of the curves showed a mixed but tending to the
gradual reduction in the levels of deceleration, as in-
creased static charge. This observation could not be ex-
tended to the curve of 0.025 kg, because the material had
very high level of deceleration, making it impractical to
continue testing.
When evaluating the individual performance of the
curves in Figure 3 and compare them to the critical ac-
celeration of some products [11], evidences that coconut
fiber pads without additives was effective to protect
Figure 2. Performance of coconut fiber pad without agglu-
tinants subjected to drop testing; means of three cumulative
impacts, drop height of 0.30 m, in the static load range be-
tween 0.11 - 0.94 kPa, at 21˚C ± 2˚C e 60% ± 3% RH.
Figure 3. Performance of coconut fiber pad without agglu-
tinants subjected to drop testing and correlation with pro-
duct resistances: means of three cumulative impacts from a
drop height 0.30 m, in the static load range between 0.47 -
0.75 kPa; at 21˚C ± 2˚C e 60% ± 3% RH.
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Testing the Use of Coconut Fiber as a Cushioning Material for Transport Packaging
154
products with fragility levels lower than 40 G, provided
that the drop conditions of the 0.075 and 0.100 kg are
used, which are capable of decelerating the impact of a
load of 0.55 kPa to 28 and 19 G, respectively. Theoreti-
cally, coconut fiber pads without additive, when used in
small quantities such as in the curves at 0.025 kg and
0.050 kg, could only be used for protecting robust prod-
ucts such as machinery and tools with critical accelera-
tion above 100 G [12].
In this way, it was found that coconut fiber might be
effective in protecting fragile products (G factor < 60);
including apples which, according to [13], have a critical
acceleration value greater than 78 G. However, it is nec-
essary to emphasize that this condition is applicable only
to drop heights no greater than 0.30 m and to products
with a low weight x surface area ratio (0.55 kPa). In
practice, this means that a product with a fragility of 60
G and weighing approximately 0.560 kg should occupy
an area of 0.01 m2 on the fiber to ensure that, when fal-
ling from a height of 0.30 m, deceleration after impact
would not exceed 60 G. In this situation, 0.05 kg of the
coconut fiber distributed over a surface area of 0.04 m2
would provide a deceleration of 51 G, and for that reason,
would be not only the more economical option, but also,
and the same time, offer more effective protection to this
hypothetical product.
For a drop height of 0.75 m, the results of the 0.075 kg
and 0.100 kg curves are depicted in Figure 4. It can be
observed that loose coconut fiber presented a pronounced
reduction in deceleration capacity, due to the increased
drop height. However, for the condition of the 0.100 kg
curve, it still proves to be effective to protect products
considered fragile. During this test, it was possible to
estimate the loss in thickness of the coconut fiber after
successive impacts, with the loose fibers showing a loss
of more than 10%, as can be seen in Figures 5 and 6. In
comparison, it can be seen that the static load of 0.55 kPa
caused a greater loss in thickness for lower deceleration
values, both for the 0.075 kg curve as for the 0.100 kg
curve. This behaviour occurred due to the energy impact
to be absorbed by the cushioning, thereby causing the
Figure 4. Performance of coconut fiber pad without agglu-
tinants relative to the protection of products with varying
degrees of resistance: means of three cumulative impacts
from a drop height of of 0.75 m, in the static load range
between 0.47 - 0.75 kPa, at 21˚C ± 2˚C e 60% ± 3% UR.
deformation of the material. However, it would be inter-
esting to evaluate the loss of thickness of the pad caused
over time under load creep tests, because a smaller thick-
ness may be insufficient to protect it from shocks [14,
15].
3.3. Evaluation of the Process of Obtaining
Coconut Fiber Pads
As for the fiber pads with agglutination agents (Figure 7),
its process of obtainment was favored by the ease mold-
ing of the fiber. It was observed that the fibers take on
the desired shape by simple hand pressure, which greatly
Figure 5. Means of the deceleration and loss of thickness of
coconut fiber pad without agglutinants with initial mass of
75 g, after three cumulative drop impacts from a drop
height of 0.75 m, in the 0.47 - 0.75 kPa static load range, at
21˚C ± 2˚C e 60 ± 3% UR.
Figure 6. Means of the deceleration and loss of thickness of
coconut fiber pad without agglutinants with initial mass of
100 g, after three cumulative drop impacts from a drop
height of 0.75 m, in the 0.47 - 0.75 kPa static load range, at
21˚C ± 2˚C e 60% ± 3% UR.
Figure 7. Cushioning pads made of coconut fiber, starch
and latex.
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Testing the Use of Coconut Fiber as a Cushioning Material for Transport Packaging 155
facilitated the molding of the pads. In spite of the fact
that the agglutinants had been applied under pressure
onto the fibers, it was noticed that after drying, the starch
gel and diluted latex were found to be present for the
most part only at the outer surface of the pads.
The use of agglutinants and the molding process used
did not favor natural agglomeration of the fibers, but
instead lead to compaction of the pads, eliminating the
voids or empty spaces between the fibers which provide
resilience to the material. According to [16], cushioning
resilience depends on the orientation of the fibers and,
when fibers are rolled up, frayed and tangled up, this
procedure results in better cushioning properties due to
its greater resilience, once the fiber is aligned in the same
direction in which the force is applied.
3.4. Behavior under Shock of Coconut Fiber
Pads
The results reveal that the use of agglutinants did not
contribute to increasing the performance of the fiber pads
as cushioning material. As for the molded coconut fiber,
the curves of each type of material are compared in Fig-
ures 8 and 9, for a static load ranging from 0.11 to 0.48
kPa, and thickness of 0.025 m and 0.050 m, respectively.
Among the pads evaluated, fibers without added aggluti-
nants stood out as having better performance than the
other alternatives tested, in view of the fact that with in-
creasing static load, they exhibited the greatest capacity
to reduce impact acceleration.
As for the pads formed using latex, higher acceleration
values were observed, probably because the fibers em-
bedded in or covered by vulcanized rubber are less effec-
Figure 8. Comparison between the shock test results for
pads of 0.025 m thickness and made of fibrous material for
a drop height of 0.30 m, in the 0.11 - 0.48 kPa static load
range at 21˚C ± 2˚C e 60% ± 3% UR.
Figure 9. Comparison between the shock test results for
pads of 0.050 m thickness and made of fibrous material for
a drop height of 0.30 m, in the 0.11 - 0.48 kPa static load
range at 21˚C ± 2˚C e 60% ± 3% UR.
tive for cushioning purposes [4]. As for the starch gel,
there was a behavior similar to latex. However, it is im-
portant emphasize that the addition of plasticizer(s) to the
starch gel could provide greater malleability after drying
[17], and maybe lead coconut fiber to producing better
results.
4. Conclusion
Based on the shock tests it was concluded that coconut
fiber as tested in its natural form presented better cush-
ioning effect as compared to pads of fiber molded with
agglutinants. The cushioning effect of the fiber was en-
hanced because of the higher length of the fiber produced
from the green coconut husk. However, the use of agglu-
tination agents increase the possibilities for use of coir as
an alternative cushioning material since they facilitate
handling and may improve the resilience of pads.
5. Acknowledgements
The authors gratefully acknowledge the research funds
from Fundação de Amparo à Pesquisa do Estado de São
Paulo (FAPESP) and the scholarship from Conselho
Nacional de Desenvolvimento Científico e Tecnológico
(CNPq).
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