FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10, rule 13)
1. Title of the invention: A FOAM COMPOSITION AND IMPLEMENTATIONS THEREOF
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai Maharashtra 400 030, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

FIELD OF INVENTION
[0001] The subject matter described herein relates to a foam composition and in particular, relates to a polyurethane foam composition, and further relates to a process of preparing the foam and its uses thereof.
BACKGROUND OF THE INVENTION
[0002] Sound attenuation at low frequencies poses a serious challenge in many applications, such as automobiles, aircraft, industrial machinery, artillery and mining explosions, wind turbines, compressors, and air-conditioning units as most commercially available acoustic materials exhibit high sound absorption coefficients at relatively medium to high frequencies. Often, low-frequency sound waves cannot be effectively absorbed by a single-phase medium. Low-frequency sounds are harmful to human health over long-term exposure and may lead to hearing impairment, neurasthenia, and cardiovascular ailments.
[0003] Automobile tires have air cavities that primarily transmit low-frequency sound waves which are generated from various mechanical contacts, relative motion between mechanical components, and the contact of the tire with the road. Minimizing the low-frequency noise provides a better experience while driving in addition to safety. The advent of electric vehicles in the last decade with a focus on reducing air and noise pollution is the key driver towards developing acoustic materials that can absorb low-frequency noises. In addition, industrial machinery is another source of low-frequency noises that can lead to temporary hearing losses in workers. This temporary hearing impairment can result in potential accidents highlighting the need for acoustic materials which can effectively reduce low-frequency noises.
[0004] DE102017207596A1 provides a pneumatic vehicle tire with polyurethane foam as a noise absorber and an adhesive comprising a butyl rubber with polyolefin and hydrocarbon. WO2017028963A1 provides a pneumatic vehicle tire comprising sound absorption material integrated with the pneumatic vehicle tire along with an applied adhesion promoter, wherein the sound absorption material is foam, glass wool, rock wool, cork, polystyrene, felt, fleece or schlingenware. However, the

absorption of low-frequency noises in automobiles and industries remains a challenge. Therefore, a sustainable, versatile material that can be prepared by simple cost-effective methods, that can be easily utilized in various real-world applications, and also showcase higher sound absorption at low-frequency ranges is largely sought.
SUMMARY OF THE INVENTION
[0005] In an aspect of the present disclosure, there is provided a foam composition
comprising a polymerized product of a polyol with a diisocyanate and a cellulose
filler, wherein the cellulose filler is in a weight percentage range of 1 to 10% with
respect to total weight of polyol and diisocyanate.
[0006] In another aspect of the present disclosure, there is provided a process for
preparing a foam composition comprising a polymerized product of a polyol with
a diisocyanate and a cellulose filler, the process comprising: contacting a polyol
and a cellulose filler with a diisocyanate under stirring in a speed range of 1500 to
2000 rpm to obtain the composition, wherein the cellulose filler is in a weight
percentage range of 1 to 10% with respect to total weight of polyol and
diisocyanate.
[0007] In another aspect of the present disclosure, there is provided an absorbent
article comprising a foam composition comprising a polymerized product of a
polyol with a diisocyanate and a cellulose filler, wherein the cellulose filler is in a
weight percentage range of 1 to 10% with respect to total weight of polyol and
diisocyanate.
[0008] In yet another aspect of the present disclosure, there is provided a tire
comprising a foam composition comprising a polymerized product of a polyol with
a diisocyanate and a cellulose filler, wherein the cellulose filler is in a weight
percentage range of 1 to 10% with respect to total weight of polyol and
diisocyanate.
[0009] In one more aspect of the present disclosure, there is provided use of a foam
composition comprising a polymerized product of a polyol with a diisocyanate and
a cellulose filler, wherein the cellulose filler is in a weight percentage range of 1 to
10% with respect to total weight of polyol and diisocyanate.

[0010] These and other features, aspects, and advantages of the present subject matter will be better understood with reference to the following description and appended claims. This summary is provided to introduce a selection of concepts in a simplified form. This summary is not intended to identify key features or essential features of the disclosed subject matter, nor is it intended to be used to limit the scope of the disclosed subject matter.
BRIEF DESCRIPTION OF DRAWINGS
[0011] In order that the disclosure may be readily understood and put into practical
effect, reference will now be made to exemplary embodiments as illustrated with
reference to the accompanying figures. The figures together with a detailed
description below, are incorporated in and form part of the specification, and serve
to further illustrate the embodiments and explain various principles and advantages,
in accordance with the present disclosure.
[0012] Figure 1 depicts the foam composition of the present disclosure and neat
polyurethane foam, in accordance with an implementation of the present disclosure.
[0013] Figure 2 depicts scanning electron microscopic images of the foam
composition with varying weight percentages of the cellulose filler of the present
disclosure and neat polyurethane foam, in accordance with an implementation of
the present disclosure.
[0014] Figure 3 depicts the elastic modulus of (a) existing low-density foams and
(b) the foam composition of the present disclosure with neat polyurethane foam, in
accordance with an implementation of the present disclosure.
[0015] Figure 4 depicts cyclic compression testing of foam composition (a)
representative PU foam compressed to 10 cycles (b) peak load for each cycle (c)
percentage drop in peak stress with loading cycles for all PU foam composition, in
accordance with an implementation of the present disclosure.
[0016] Figure 5 depicts the energy loss coefficient (ELC) depicting the energy loss
in each cycle at a strain rate of 0.01 s-1 for (a) low-density foam (b) the
foam composition of the present disclosure, in accordance with an implementation
of the present disclosure.

[0017] Figure 6 depicts storage modulus as a function of frequency for (a) low-density foam (b) the foam composition of the present disclosure, in accordance with an implementation of the present disclosure.
[0018] Figure 7 depicts a plot of the sound absorption coefficient of the foam composition with respect to the frequency range, in accordance with an implementation of the present disclosure.
[0019] Figure 8 depicts vehicle level tyre in-cabin noise testing on course concrete at (a) 60 kmph and (b) 80 kmph, in accordance with an implementation of the present disclosure.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Those skilled in the art will be aware that the present disclosure is subject
to variations and modifications other than those specifically described. It is to be
understood that the present disclosure includes all such variations and
modifications. The disclosure also includes all such steps, features, compositions,
and compounds referred to or indicated in this specification, individually or
collectively, and any and all combinations of any or more of such steps or features.
Definitions
[0021] For convenience, before further description of the present disclosure,
certain terms employed in the specification, and examples are delineated here.
These definitions should be read in the light of the remainder of the disclosure and
understood as by a person of skill in the art. The terms used herein have the
meanings recognized and known to those of skill in the art, however, for
convenience and completeness, particular terms and their meanings are set forth
below.
[0022] The articles "a", "an" and "the" are used to refer to one or to more than one
(i.e., to at least one) of the grammatical object of the article.
[0023] The terms "comprise" and "comprising" are used in the inclusive, open
sense, meaning that additional elements may be included. It is not intended to be
construed as "consists of only".
[0024] Throughout this specification, unless the context requires otherwise the
word "comprise", and variations such as "comprises" and "comprising", will be

understood to imply the inclusion of a stated element or step or group of elements or steps but not the exclusion of any other element or step or group of elements or steps.
[0025] The term "including" is used to mean "including but not limited to". "including" and "including but not limited to" are used interchangeably. [0026] The term “polyol” refers to compounds comprising one or more hydroxyl groups and is selected from polyester, polyether, polybutadiene, polycarbonate, and polyacrylate polyol. The polyol further comprises a blowing agent. The blowing agent refers to materials which are capable of providing cellular structure via a foaming process in polymers. The blowing agent includes but is not limited to water, pentane, chlorofluorocarbons, methyl formate, and dimethoxymethane. The polyol used in the present disclosure comprises a component selected from polyester, polyether, polybutadiene, polycarbonate, polyacrylate polyol or combinations thereof with a blowing agent. In some embodiments, the polyol comprises a component selected from polyester, polyether, polybutadiene, polycarbonate, polyacrylate polyol, or combinations thereof. The polyol reacts with a diisocyanate to obtain a polymer which primarily contains urethane linkages and is referred to as polyurethane.
[0027] The term “diisocyanate” refers to compounds comprising two isocyanate groups (NCO). In the present disclosure, the term diisocyanate refers to a compound selected from methylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, aromatic isocyanates, or combinations thereof. Diisocyanate reacts with the polyol and forms a polymerized product which is polyurethane-based polymer.
[0028] The term “cellulose filler” refers to a material rich in cellulose and acts as filler. In the present disclosure, the cellulose filler is selected from saw-dust, wood dust, wood chips, cotton fibers, or dried hemp. In the present disclosure, the cellulose filler enhances the acoustic and mechanical properties of the foam composition. The foam composition comprising the cellulose filler embedded as micro-inclusions in the cell walls of the foam impede sound wave propagation and exhibit improved sound absorption properties.

[0029] The term “polymerized product” refers to a polymer obtained by reacting a polyol with a diisocyanate and a cellulose filler. The polymerized product in the present disclosure is polyurethane which comprises the cellulose filler embedded in the cell walls of the polyurethane foam.
[0030] The term “sound absorption coefficient” is used to evaluate the sound absorption efficiency of materials and is a ratio of absorbed energy to incident energy. In the present disclosure, the foam composition is an acoustic material that is capable of absorbing sound and has an absorption coefficient in a range of 0.1 to 0.5 in a low-frequency range of 150 to 650 Hz. The foam composition absorbs sound and provides a reduced decibel in a range of 0.6 to 5.1 in a frequency range of 150 to 650Hz.
[0031] The term “elastic modulus” refers to the ability of a material to resist deformation when stress is applied to it. In the present disclosure, the elastic modulus of the foam composition is in a range of 0.03 to 0.3 MPa.
[0032] The term “low-density foam” refers to an open-cell flexible foam having a density in the range of 70 to 100 kg/m3. The pores of the low-density foam are in a range of 200 to 300 µm with cell wall thickness in a range of 50 to 100 µm. [0033] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a range of 1 to 10 % should be interpreted to include not only the explicitly recited limits of 1 % to 10 % but also to include sub-ranges, such as 2 to 9 %, 3 to 8 %, and so forth, as well as individual amounts, within the specified ranges, such as 1 %, 2.5%, 3.5%, 5% and 10 % for example.
[0034] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the

disclosure, the preferred methods, and materials are now described. All publications mentioned herein are incorporated herein by reference.
[0035] The present disclosure is not to be limited in scope by the specific embodiments described herein, which are intended for the purposes of exemplification only. Functionally equivalent products, compositions, and methods are clearly within the scope of the disclosure, as described herein.
[0036] As discussed in the background, it is well understood that low-frequency noises posing health hazards need to be avoided, and materials which can effectively absorb the low-frequency noises are essentially required. Accordingly, the present disclosure provides a foam composition comprising a polymerized product of a polyol with a diisocyanate and a cellulose filler. The polymerized product is polyurethane obtained by polymerization of polyol and diisocyanate and the cellulose filler gets embedded on the walls of the polyurethane. The cellulose filler is rich in cellulose and provides mechanical and acoustic properties. The polymerized product which is solid flexible polyurethane foam reinforced with the cellulose filler embedded as micro-inclusions in the cell walls of the foam hinder sound wave propagation and exhibit improved sound absorption properties, especially at low-frequency ranges. The porous foam composition embedded with the cellulose filler provides the enhanced noise attenuation properties. Thus, the present disclosure provides a cellulose-rich polyurethane foam obtained as a polymerized product of a polyol with a diisocyanate and a cellulose filler, wherein the cellulose filler is in a weight percentage range of 1 to 10% with respect to total weight of the polymerized product which exhibits sound absorption coefficient in a range of 0.1 to 0.5 with reduced decibel range of 0.6 to 5.1 in a frequency range of 150 to 650Hz. The present disclosure also provides a process for preparing the foam composition.
[0037] In an embodiment of the present disclosure, there is provided a foam composition comprising a polymerized product of a polyol with a diisocyanate and a cellulose filler, wherein the cellulose filler is in a weight range of 1 to 10% with respect to total weight of polyol and diisocyanate. In another embodiment of the present disclosure, the cellulose filler is 10 wt% with respect to total weight of

polyol and diisocyanate. In yet another embodiment of the present disclosure, the cellulose filler is 5 wt % with respect to total weight of polyol and diisocyanate. In one another embodiment of the present disclosure, the cellulose filler is 1 wt % with respect to total weight of polyol and diisocyanate.
[0038] In an embodiment of the present disclosure, there is provided a foam composition as disclosed herein, wherein the polyol and the diisocyanate is in weight ratio range of 10:2 to 10:7. In another embodiment of the present disclosure, wherein the polyol and the diisocyanate is in weight ratio range of 10:3 to 10:6. In yet another embodiment of the present disclosure, the polyol and the diisocyanate is in a weight ratio of 10:6.
[0039] In an embodiment of the present disclosure, there is provided a foam composition comprising a polymerized product of a polyol with a diisocyanate and a cellulose filler, wherein the cellulose filler is in a weight range of 1 to 10% with respect to total weight of polyol and diisocyanate; and the polyol and the diisocyanate is in weight ratio range of 10:2 to 10:7.
[0040] In an embodiment of the present disclosure, there is provided a foam composition as disclosed herein, wherein the cellulose filler is selected from saw-dust, wood dust, wood chips, cotton fibers, dried hemp, or combinations thereof; and has particle size in a range of 20 to 60 µm. In another embodiment of the present disclosure, the cellulose filler is saw-dust. In yet another embodiment of the present disclosure, the cellulose filler is saw-dust and has a particle size in a range of 30 to 60 µm. In one another embodiment of the present disclosure, the cellulose filler is saw-dust and has a particle size in a range of 40 to 60 µm.
[0041] In an embodiment of the present disclosure, there is provided a foam composition as disclosed herein, wherein the composition exhibits a sound absorption coefficient in a range of 0.1 to 0.5 with a reduced decibel range of 0.6 to 5.1 in a frequency range of 150 to 650 Hz. In another embodiment of the present disclosure, wherein the composition exhibits sound absorption coefficient in a range of 0.1 to 0.4 with a reduced decibel range of 0.63 to 5.1 in a frequency range of 150 to 650Hz.

[0042] In an embodiment of the present disclosure, there is provided a foam composition as disclosed herein, wherein the composition has density in a range of 70 to 105 kg/m3; and pore size in a range of 200 to 300 µm.
[0043] In an embodiment of the present disclosure, there is provided a foam composition as disclosed herein, wherein the composition has elastic modulus in a range of 0.03 to 0.3MPa. In another embodiment of the present disclosure, the composition has an elastic modulus in 0.3MPa.
[0044] In an embodiment of the present disclosure, there is provided a foam composition comprising a polymerized product of a polyol is selected from polyester, polyether, polybutadiene, polycarbonate, polyacrylate polyol, or combinations thereof, with a diisocyanate selected from methylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, aromatic isocyanates, or combinations thereof; and a cellulose filler selected from saw dust, wood dust, wood chips, cotton fibers, dried hemp, or combinations thereof, wherein the cellulose filler is in a weight range of 1 to 10% with respect to total weight of polyol and diisocyanate, the composition exhibits sound absorption coefficient in a range of 0.1 to 0.5 with reduced decibel range of 0.6 to 5.1 in a frequency range of 150 to 650Hz, the composition has density in a range of 70 to 105 kg/m3; has elastic modulus in a range of 0.03 to 0.3MPa; and pore size in a range of 200 to 300 µm.
[0045] In an embodiment of the present disclosure, there is provided a foam composition comprising a polymerized product of a polyol with methylene diisocyanate in a weight ratio of 10:6 and saw dust, wherein saw dust is in a weight range of 1 to 10% with respect to total weight of polyol and diisocyanate, the composition exhibits sound absorption coefficient in a range of 0.1 to 0.5 with reduced decibel range of 0.6 to 5.1 in a frequency range of 150 to 650Hz, the composition has density in a range of 70 to 105 kg/m3; has elastic modulus in a range of 0.03 to 0.3MPa; and pore size in a range of 200 to 300 µm.
[0046] In an embodiment of the present disclosure, there is provided a foam composition comprising a polymerized product of a polyol with a diisocyanate and a cellulose filler, wherein the cellulose filler is in a weight range of 1 to 10% with

respect to total weight of polyol and diisocyanate, and the foam composition has varying foam thickness in a range of 2 mm to 15 mm. In another embodiment of the present disclosure, the foam composition has varying foam thickness in a range of 5 mm to 15 mm.
[0047] In an embodiment of the present disclosure, there is provided a process for preparing the composition as disclosed herein, the process comprising contacting a polyol and a cellulose filler with a diisocyanate under stirring in a speed range of 1500 to 2000 rpm to obtain the composition.
[0048] In an embodiment of the present disclosure, there is provided a process for preparing the composition as disclosed herein, the process comprising contacting a polyol and a cellulose filler with a diisocyanate under stirring in a speed range of 1500 to 2000 rpm and allowing to cure for a time period in a range of 30 to 60 hours to obtain the composition. In another embodiment of the present disclosure, the composition is allowed to cure for a time period of 48 hours.
[0049] In an embodiment of the present disclosure, there is provided a process for preparing the composition comprising a polymerized product of a polyol with a diisocyanate and a cellulose filler, the process comprising contacting a polyol and a cellulose filler under stirring followed by addition of a diisocyanate under stirring in a speed range of 1500 to 2000 rpm and allowing to cure for a time period in a range of 30 to 60 hours to obtain the composition, wherein the cellulose filler is in a weight range of 1 to 10% with respect to total weight of polyol and diisocyanate and the polyol and the diisocyanate is in a weight ratio range of 10:2 to 10:7. [0050] In an embodiment of the present disclosure, there is provided a process for preparing the composition as disclosed herein, the process comprising contacting a polyol and saw-dust with methylene diisocyanate under stirring speed of 2000 rpm and allowing to cure for a time period of 48 hours to obtain the composition, wherein the saw-dust is in a weight percentage range of 1 to 10% with respect to total weight of polyol and diisocyanate and the polyol and the diisocyanate is in weight ratio of 10:6.
[0051] In an embodiment of the present disclosure, there is provided a process for preparing the composition as disclosed herein, wherein the composition is made in

desired shapes and sizes and may not involve any external force for the formation
of the foam composition.
[0052] In an embodiment of the present disclosure, there is provided an absorbent
article comprising a foam composition comprising a polymerized product of a
polyol with a diisocyanate and a cellulose filler, wherein the cellulose filler is in a
weight range of 1 to 10% with respect to total weight of polyol and diisocyanate.
[0053] In an embodiment of the present disclosure, there is provided an absorbent
article comprising a foam composition as disclosed herein with a low-density foam.
In another embodiment of the present disclosure, wherein the low-density foam has
density in a range of 70 to 100 kg/m3; pore size in a range of 200 – 300 µm with
cell wall thickness in a range of 50 to 100 µm.
[0054] In an embodiment of the present disclosure, there is provided a tire
comprising a foam composition comprising a polymerized product of a polyol with
a diisocyanate and a cellulose filler, wherein the cellulose filler is in a weight range
of 1 to 10% with respect to total weight of the polymerized product.
[0055] In an embodiment of the present disclosure, there is provided a tire
comprising a foam composition with a low-density foam.
[0056] In an embodiment of the present disclosure, there is provided use of a foam
composition comprising a polymerized product of a polyol with a diisocyanate and
a cellulose filler, wherein the cellulose filler is in a weight range of 1 to 10% with
respect to total weight of polyol and diisocyanate.
[0057] In an embodiment of the present disclosure, there is provided use of a foam
composition as disclosed herein in various industrial applications that include but
are not limited to automobiles, aircraft, industrial machinery, artillery and mining
explosions, wind turbines, compressors, and air-conditioning units.
[0058] Although the subject matter has been described with reference to specific
embodiments, this description is not meant to be construed in a limiting sense.
Various modifications of the disclosed embodiments, as well as alternate
embodiments of the subject matter, will become apparent to persons skilled in the
art upon reference to the description of the subject matter. It is therefore

contemplated that such modifications can be made without departing from the spirit or scope of the present subject matter as defined.
EXAMPLES
[0059] The disclosure will now be illustrated with the working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one ordinary person skilled in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices, and materials are described herein. It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may apply. [0060] The forthcoming example explains how the present disclosure provides a foam composition comprising a polymerized product obtained from a polyol and a diisocyanate with a cellulose filler. The present disclosure provides a simple process of preparing the foam composition which can be carried out at room temperature and involves a simple process without any external applied forces or any specific reagents. The present disclosure also provides an article comprising the foam composition and a low-density foam. The polyol used in the present disclosure is selected from polyester, polyether, polybutadiene, polycarbonate, and polyacrylate polyol. The diisocyanate is selected from methylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and aromatic isocyanates. The cellulose filler is selected from saw dust, wood dust, wood chips, cotton fibers, or dried hemp. The cellulose filler is of particle size in a range of 20 to 60 µm.
Materials and Methods
[0061] For the purpose of the present disclosure, polyol used is formulated type containing a proprietary blowing agent of grade shivapol-210, the diisocyanate is methylene diisocyanate of grade shivapol-002. The cellulose filler is saw-dust

which is sieved to obtain particle size in the range of 20 to 40 µm. The saw-dust used in the present disclosure was commercially procured from market.
EXAMPLE 1
Process of preparing foam composition
[0062] The process of the foam composition comprised obtaining a polymerized product by contacting the polyol with the cellulose filler and the diisocyanate under stirring followed by allowing to cure to obtain the foam composition. The polyol and methylene diisocyanate were taken in weight ratio of 10:6. Saw-dust (cellulose filler) of particle size 20 to 40 µm was used for the preparation of the foam composition. The amount of saw dust corresponded to 1 to 10% by total weight of the polyol and methylene diisocyanate. In an example, 10g of the polyol was mixed with 0.8g (5%) of saw-dust under sonication and stirred followed by the addition of 6g of methylene diisocyanate under stirring at a speed of 2000 rpm to obtain the composition. The composition was then transferred to a mold of the desired shape and was allowed to cure for a time period of 48 hours to obtain the foam composition. The weight ratio of the polyol and the diisocyanate was retained within the range of 10:2 to 10:7. The polyurethane (PU) foam composition obtained using 5% of saw-dust is represented as PU_5wt%. Hence PU_1wt% and PU_10wt% represent the foam composition comprising 1% of saw-dust and 10% of saw-dust respectively with respect to the total weight of the polyol and diisocyanate. The foam prepared without saw-dust is represented as neat PU foam and was prepared for comparative purposes.
[0063] It was observed during preparation of the foam composition that the higher stirring speed was essential to obtain the foam composition with required rigidity, as the stirring speed in range of 1500 to 2000 rpm provided complete dispersion of the saw-dust in polyurethane and a uniform foam structure. Further, the weight % of the saw-dust was critical to be within 1 to 10% by the total weight of the polyol and methylene diisocyanate. A lower weight % of saw dust (< 1%) did not result in a rigid foam composition and a higher weight of saw dust (>10%) resulted in brittle foam composition which is unsuitable as a sound absorbent.

EXAMPLE 2
Characterization of the foam composition
[0064] The bulk density of the foam composition was measured using the mass by
given volume of the foam. The mass of foam was evaluated using the Mettler
Toledo weighing balance and volume was evaluated from dimensions measured
using vernier calliper. Relative density of the foam composition of the present
disclosure was calculated using rule of mixture as provided in formula (1) below.

ρc is density of solid PU and saw-dust, Wf is weight fraction of saw-dust, ρf is density of saw-dust which is 0.74 g/cc, Wm is weight fraction of PU which is 0.95 and ρm is density of solid PU which is 1.2 g/cc. Table 1 provides the relative density and the density of the foam composition. The density of the foam composition is lesser than the neat PU foam which indicated the porous nature of the foam composition. Figure 1 depicts the foam composition PU_5wt% of the present disclosure and neat PU foam. Figure 1 also confirmed that the foam composition is highly porous as well as rigid.
Table 1

Foam composition Density (kg/m3) Relative density(%)
Neat PU foam 100±6 8.33
PU_1wt% 90±7.5 7.56
PU_5wt% 70±2.7 6.38
PU_10wt% 94±9.9 8.31
[0065] SEM analysis of the foam composition confirmed that the foam composition of the present disclosure is porous, and a uniform microstructure was observed. The pore size of the foam was found to be in range of 200 to 300 µm. Figure 2 depicts the SEM images of the foam composition under scales such as 1mm, 100 µm and 10 µm.

[0066] The quasi-static compression testing and multiple cyclic compression testing was carried out using Tinius Olsen, United Kingdom for the foam samples. The quasi-static compression testing was carried out to evaluate the elastic modulus and cyclic compression testing was done to evaluate energy absorption in each cycle. In order to carry out the compression testing the cylindrical foam compositions with a diameter of 10 mm and height of 6.3 mm were compressed to a strain of 80%. The strain was evaluated from the displacement of the top platen. Peak stress is the stress value corresponding to 80 % strain during each cycle. [0067] Compression testing was carried out for the foam composition as compared to the existing low-density foam having relative densities of 0.57%, 1.33%, 1.91%, 2.83% and 5%. It was found that the foam composition of the present disclosure (represented as 1wt%, 5wt% and 10wt% (Figure 3b)) were all strain rate sensitive and had the highest elastic modulus of 0.3MPa compared to the existing foams. The existing low-density foam of relative density 0.57% exhibited an elastic modulus of 0.09MPa (Figure 3a) which confirmed that the foam composition of the present disclosure was high stress resistant and mechanically rigid. This mechanical rigidity is essential for a foam composition as a sound absorbing layer, towards use in tire construction.
[0068] Cyclic compression testing was carried out for the foam composition
which confirmed that peak stress dropped in consequent cycles (Figure 4a-c). Figure 4(a) depicts the loading-unloading curve for the PU foam samples. At a strain value of 60 % the cell walls started to compress against each other, as a result of which the stress values showed an abrupt rise. The loading curves for all 10 cycles were over-lapping on each other and similarly, the un-loading curves also overlapped with each other.
[0069] Figure 4 (b) is the enlarged view of peak stress for each cycle. It was evident from Figure 4 (b) that the peak stress in the subsequent cycle dropped with respect to the previous cycle. The slight drop in peak stress was attributed to the structural weakening of microstructure with each subsequent cycle.
[0070] Figure 4 (c) is the fraction peak stress for each cycle with respect to 1st cycle. The drop in peak stress was also a function of weight % of saw-dust. Even

after 10 cycles of loading-unloading the relative drop (with respect to 1st cycle) in peak stress was higher for PU_10 wt. % which was about to 80 % strain value. Also, by comparing peak stress of neat PU and PU_10 wt. %, the PU_10 wt. % foam had higher peak stress. The drop of peak stress was due to the addition of saw-dust in the foam composition which provided stiffer cell walls to the foam.
[0071] ELC (Energy Loss Coefficient) measurements were done for the foam composition of the present disclosure in comparison to the existing low-density foams of relative densities 0.57%, 1.33%, 1.91%, 2.83% and 5% (Figure 5a-b). Energy Loss Coefficient is a measure of energy dissipated in each cycle. It was evaluated using the ratio of hysteresis loop area to the area under the loading cycle. This ratio was multiplied by 100 to obtain the ELC value for the respective cycle. It was understood that ELC was lesser for the PU foam of present disclosure and ELC % was higher than the existing foams. This confirmed that the PU foam of the present disclosure was stable compared to the existing foams.
[0072] From the dynamic mechanical thermal analysis, it was understood that elastic modulus was higher for PU foam of the present disclosure when compared to the existing foams (Figures 6a-b). Dynamic mechanical thermal analysis (DMTA; PerkinElmer, USA) was performed to study the effect of sawdust addition and relative density on the storage modulus (E') of the foams. The cylindrical foam composition of the present disclosure of diameter of 10 mm and a height of 6.3 mm were compressed to a strain value of 0.4% and were tested within elastic limits. The frequency was altered in a range of 0.1 - 30 Hz at room temperature. It was observed that the storage modulus for the foam composition was almost 4 times higher for PU_10 wt. % foam. This indicated that the foam composition had a higher tendency to store energy within itself. Also, the values of storage modulus increased with the frequency which confirmed the strain-rate sensitive behavior of the foam composition.
EXAMPLE 3
Acoustic analysis of the foam composition
[0073] The foam composition of the present disclosure prepared in Example 1 was
subjected to the determination of sound absorption coefficient. The foam

composition prepared with varying thicknesses of 6 mm, 10mm and 15 mm was subjected to acoustic analysis at a low frequency range of 150 to 650Hz. The sound absorption coefficient and the corresponding reduced decibel were calculated and is tabulated in Tables 2, 3, and 4 below. Table 2

Foam sample 6 mm thickness

α 150/db reduction 150 α 400/db reduction 400 α 600/db reduction 600 Weight of the foam (g)
Neat PU 0.07/0.63 0.08/0.72 0.11/1 19
PU_1wt% 0.075/0.67 0.09/0.82 0.13/1.2 170
PU_5wt% 0.077/0.7 0.09/0.82 0.12/1.1 132
PU_10wt% 0.072/0.65 0.09/0.82 0.11/1 178
Table 3

Foam sample 10 mm thickness

α 150/db reduction 150 α 400/db reduction 400 α 600/db reduction 600 Weight of the foam (g)
Neat PU 0.08/0.73 0.12/1.1 0.2/1.9 315
PU_1wt% 0.08/0.74 0.13/1.2 0.23/2.3 284
PU_5wt% 0.08/0.77 0.13/1.2 0.17/1.6 221
PU_10wt% 0.08/0.69 0.14/1.5 0.18/1.8 296
Table 4

Foam sample 15 mm thickness

α 150/db reduction 150 α 400/db reduction 400 α 600/db reduction 600 Weight of the foam (g)
Neat PU 0.1/0.9 0.2/1.6 0.3/3.6 473
PU_1wt% 0.1/1 0.2/2.6 0.42/4.7 426
PU_5wt% 0.1/0.9 0.2/2.5 0.4/4.2 331

PU_10wt% 0.1/0.9 0.3/2.7 0.4/5.1 445
[0074] From Tables 2, 3 and 4 it can be observed that the foam composition of the present disclosure exhibited a higher sound absorption coefficient and reduced decibel when compared to the neat PU foam. This was because the addition of saw dust to the foam composition provided enhanced acoustic property to the foam composition. Also, it was understood that irrespective of thickness, the absorption coefficient was higher for the foam composition PU_1wt% as compared to neat PU, further, it was evident that as thickness increased the absorption coefficient also increased. Further, the weight of the foam composition even after increasing the thickness was maintained within the standard weight range of an additive to the tire. This illustrated that the foam composition of the present disclosure was suitable to be added to the tire as sound absorbing material without further increasing the weight of the tire. Thus, the developed foam composition of the present disclosure demonstrated higher sound absorption properties in the frequency range of 150 – 600 Hz.
EXAMPLE 4 In-cabin noise testing
[0075] The foam composition of the present disclosure was used in tyre fabrication and the tyre was subjected to in-cabin noise testing. Vehicle level tyre in-cabin noise testing was carried out using IS 12832 (2010). The testing assembly included three microphones for in-cabin test: one each at drive ear (left and right) and another at rear seat (passenger location). Vehicle was run on a concrete course at two different speeds 60kmph and 80 kmph. 5 dBA to 7dBA noise reduction was observed with the disclosed foam at the cavity peak. In the overall cavity frequency region of 200 Hz to 250 Hz, noise reduction of 2 dBA to 3 dBA was observed at both driver ear and passenger location. Thus it was evident that tyre made of the foam composition of the present disclosure, provided significant reduction on cavity frequency range and no deterioration on other frequency range as shown in Figures 8 (a) and (b).

Advantages of the present disclosure
[0076] The present disclosure provides a foam composition comprising the polymerized product polyurethane obtained from a polyol and diisocyanate with a cellulose filler. The cellulose filler of the present disclosure provides the mechanical and acoustic properties of the foam composition. The present disclosure provides a simple, cost-effective process for preparing the foam composition. The foam composition can be prepared in desired thickness and shape and does not involve any complicated preparation process. The foam composition has a uniform microstructure with the cellulose filler homogenously dispersed providing improved mechanical property to the foam composition. The foam composition exhibits a higher elastic modulus and is thermally stable up to 260 ℃. The add-on advantage is that the cellulose filler which saw-dust is available in abundance and cause of carcinogenic and noncarcinogenic effects in the upper and lower respiratory systems of humans can be utilized most favorably. The foam composition can be conveniently used in the tire construction towards sound attenuation of low-frequency sound waves, thereby addressing hazardous aftereffects of exposure to low frequency waves. Hearing loss can also be avoided by making ear plugs for the industrial workers by using the foam composition of the present disclosure.

I/We Claim:
1. A foam composition comprising a polymerized product of a polyol with a diisocyanate and a cellulose filler, wherein the cellulose filler is in a weight range of 1 to 10% with respect to the total weight of polyol and diisocyanate.
2. The composition as claimed in claim 1, wherein the polyol and the diisocyanate are in a weight ratio range of 10:2 to 10:7.
3. The composition as claimed in claim 1, wherein the polyol is selected from polyester, polyether, polybutadiene, polycarbonate, and polyacrylate polyol or combinations thereof; and the diisocyanate is selected from methylene diisocyanate, toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, aromatic isocyanates, or combinations thereof.
4. The composition as claimed in claim 1, wherein the cellulose filler is saw dust, wood dust, wood chips, cotton fibers, dried hemp, or combinations thereof; and has a particle size in a range of 20 to 60 µm.
5. The composition as claimed in claim 1, wherein the composition exhibits a sound absorption coefficient in a range of 0.1 to 0.5 with a reduced decibel range of 0.6 to 5.1 in a frequency range of 150 to 650Hz.
6. The composition as claimed in claim 1, wherein the composition has a density in a range of 70 to 105 kg/m3; and pore size in a range of 200 to 300 µm.
7. The composition as claimed in claim 1, wherein the composition has an elastic modulus in a range of 0.03 to 0.3MPa.
8. A process for preparing the composition as claimed in claim 1, the process comprising:
contacting a polyol and a cellulose filler with a diisocyanate under stirring in a speed range of 1500 to 2000 rpm to obtain the composition.
9. The process as claimed in claim 8, wherein the composition is allowed to cure for a time period in a range of 30 to 60 hours.
10. An absorbent article comprising the composition as claimed in claim 1.
11. The article as claimed in claim 10, further comprising a low-density foam.

12. The article as claimed in claim 11, wherein the low-density foam has density in a range of 70 to 100 kg/m3; pore size in a range of 200 – 300 µm with cell wall thickness in a range of 50 – 100 µm
13. A tire comprising the composition as claimed in claim 1.
14. The tire as claimed in claim 13, further comprises a low-density foam.