Description:TECHNICAL FIELD
[0001] The present disclosure relates to a process for recycling waste polymeric material. Further, the presently claimed invention also relates to a shaped article obtained by shaping extrudates and a process for preparing the same.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Plastics play a major role in the current era. Most of the plastics today are non-bio degradable, and hence, produce higher amounts of waste. While plastic has been one of the most cherished invention of the mankind, the short- and long-term effects of inefficient and incorrect disposal techniques have negatively impacted the living beings. As a matter of fact, a recent survey has concluded that India's per capita plastic consumption is approx. 8 gm per day, thereby leading to about 3.3 million tons of plastic waste being generated annually. The quantum of waste that is being generated today on a global scale is a warning figure and therefore requires serious steps towards recycling, reclaiming and reutilizing the waste plastic materials. To this effect, a plethora of techniques and methods for recycling and reutilizing the waste plastic have been reported.
[0004] One such process of recycling waste polymeric material is disclosed in US5914353A, wherein, the process includes taking a mixture of waste polymeric material wherein the waste polymeric material includes from about 0 to 40 percent aliphatic polyamide material; granulating and densifying the chopped mixture into fragments at least about 100 times smaller than the size of the waste polymeric material; and extruding the ground mixture at a temperature that does not exceed the temperature at which the largest portion of polymer based material decomposes.
[0005] Another process disclosed in US4250222A proposes - coarsely grinding a mixture of two or more mutually incompatible thermoplastic resins; incorporating into the coarsely ground thermoplastic resin mixture, through the application of heat and pressure, from about 5 to about 25 parts of weight of a fibrous material; and forming the resin/fiber mass into an article.
[0006] US4158645A proposes applying a shearing force (e.g., using a Banbury mixer) to tear the fabric fibers into lengths no greater than about 0.25 inch to form a mixture of thermoplastic-resin and short lengths of fabric fibers. The resulting mixture is to be subjected to heat and pressure, such as by a drop mill and thus banded. After the mixture is banded, it can be calendared onto a web of fabric to form a finished reinforced sheet or extruded into various continuous forms such as sheets or strips. The process is described as being particularly useful when applied to scrap polyvinyl chloride sheet material reinforced with cotton fabric.
[0007] Of the various types of polymeric products being consumed today, a majority of them are made out of polyolefin and/or synthetic rubber. An estimate of the waste generation can be easily predicted from the perspective of a large research organization dealing in chemicals research. Such an organization would typically generate approx. 20 gm of polyolefin (particularly polypropylene) waste per day and is therefore estimated to produce approx. 2.2 tons of polyolefin waste per year. Similarly, the per capita synthetic rubber consumption (particularly in the form of nitrile gloves) for chemical handling in the organization would be approx. 16 gm per day, which amounts to 1.5 tons of waste being generated every year. On a global scale, if these figures are extrapolated considering existence of a large number of similar organizations, the resulting figure would be a tremendous waste being generated daily or annually. While there exist several technologies and processes for separately dealing with each of these waste materials, recycling becomes a challenge when the polymeric waste is a mixture of polymeric materials, for instance a mixture of polyolefins and synthetic rubber. Accordingly, there is a dire need to tackle this menace/problem.
[0008] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

OBJECTS
[0009] An object of the present disclosure is to arrive at a process for recycling a waste polymeric material comprising a mixture of a waste polyolefin and a waste synthetic rubber.
[0010] Another object of the present disclosure is to provide recycled extrudates/materials having improved properties when compared to non-recycled (or fresh) polymeric materials for deriving shaped articles therefrom.

SUMMARY
[0011] The present disclosure relates to a process for recycling waste polymeric material. Further, the presently claimed invention also relates to a shaped article obtained by shaping extrudates and a process for preparing the same.
[0012] An aspect of the present disclosure relates to a process for recycling a waste polymeric material comprising a mixture of at least one waste polyolefin and at least one waste synthetic rubber. The process includes the steps of: (a) extruding a first mixture comprising an initiator and a comminuted polyolefin at a temperature ranging from 160°C to 230°C to obtain a modified polyolefin having a melt flow index (MFI) ranging from 3 g/10 min to 70 g/10 min; (b) devulcanizing the waste synthetic rubber in presence of a devulcanizing agent to obtain a synthetic rubber powder; and (c) extruding a second mixture comprising the modified polyolefin, at least one filler and the synthetic rubber powder at a temperature ranging from 160°C to 230°C to obtain recycled extrudates.
[0013] In some embodiments, the process comprises the sub-steps of grinding the waste polyolefin to obtain the comminuted polyolefin. The comminuted polyolefin has a particle size ranging between 1 to 100 mm. The process further comprises washing and drying the comminuted polyolefin in hot air at a temperature ranging between 80°C to 150°C followed by mixing the initiator and the comminuted polyolefin to obtain the first mixture. The process also comprises extruding the first mixture at temperature ranging between 160°C to 230°C to obtain the modified polyolefin having the melt flow index ranging in between 3 g/10min to 70 g/10min.The modified polyolefin is subsequently cooled at a temperature ranging between 20°C to 30°C, followed by pelletizing the modified polyolefin.
[0014] In some embodiments, the initiator comprises organic peroxide and/or hydroperoxide selected from the group consisting of: tert-butyl peroxide, cumene hydroperoxide, pinane hydroperoxide, diisopropylphenyl hydroperoxide, dibenzoyl peroxide, dilauroyl peroxide, and diacetyl peroxide. In some embodiments, the amount of the initiator in the first mixture is in the range of 250 ppm to 10000 ppm based on the total weight of the first mixture.
[0015] In some embodiments, the devulcanizing agent is urea and/or its derivative. In some embodiments, the devulcanizing agent is added in an amount ranging from 1 wt.% to 25 wt.% based on total weight of the waste synthetic rubber.
[0016] In some embodiments, the devulcanizing is carried out at a temperature ranging between 50°C to 150°C.
[0017] In some embodiments, the filler is selected from the group consisting of: glass fibers, carbon fibers, aramid fibers, natural fibers, clay, kaolin, mica, wollastonite, silica, talc, titanium dioxide, Portland cement and mixtures thereof. In some embodiments, the filler is added in an amount ranging from 5 wt.% to 70 wt.% based on the amount of the modified polyolefin.
[0018] In some embodiments, the amount of synthetic rubber powder in the second mixture is in the range of 3 wt.% to 60 wt.% based on the amount of modified polyolefin. In some embodiments, the synthetic rubber powder has a particle size in the range of 100 microns to 10000 microns.
[0019] In some embodiments, the waste polyolefin is a polyolefin article made from polypropylene, polyethylene, and mixtures thereof. In some embodiments, is a synthetic rubber article made from nitrile rubber, butyl rubber, neoprene rubber, isoprene rubber, polybutadiene rubber and mixtures thereof.
[0020] Another aspect of the present disclosure provides a shaped article obtained by shaping the recycled extrudates obtained in the above process. The shaping is carried out by subjecting the recycled extrudates to molding and/or casting methods. In some embodiments, shaped article is selected from table coasters, pavement bricks, tiles, and aesthetic products.
[0021] Further aspect of the present disclosure relates to a process for preparing the above shaped article by shaping the recycled extrudates obtained from the process above.
[0022] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments.

DETAILED DESCRIPTION
[0023] The following is a detailed description of embodiments of the present invention. The embodiments are in such detail as to clearly communicate the invention. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
[0024] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0025] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability.
[0026] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.” It is to be appreciated that the terms "comprising", "comprises" and "comprised of" as used herein includes the terms "consisting of", "consists" and "consists of" within their meaning.
[0027] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0028] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0029] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.
[0030] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0031] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0032] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention. The terms "first", "second", "third" or "(a)", "(b)", "(c)", "(d)", etc. and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein. In case the terms "first", "second", "third" or "(A)", "(B)", and "(C)" or "(a)", "(b)", "(c)", "(d)", "I", "ii", etc. relate to steps of a method or use or assay, there is no time or time interval coherence between the steps, that is, the steps may be carried out simultaneously or there may be intervals of seconds, minutes, hours or even days between such steps, unless otherwise indicated in the application as set forth hereinabove or below.
[0033] The following discussion provides many example embodiments of the inventive subject matter. Although each embodiment represents a single combination of inventive elements, the inventive subject matter is considered to include all possible combinations of the disclosed elements. Thus if one embodiment comprises elements A, B, and C, and a second embodiment comprises elements B and D, then the inventive subject matter is also considered to include other remaining combinations of A, B, C, or D, even if not explicitly disclosed.
[0034] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0035] The present disclosure relates to a process for recycling waste polymeric materials. The present disclosure also relates to a shaped article obtained by shaping the extrudates and a process for preparation thereof.
[0036] An aspect of the present disclosure is directed to a process for recycling waste polymeric material comprising a mixture of at least one waste polyolefin and at least one waste synthetic rubber.
[0037] In some embodiments, the process includes the steps of: (a) extruding a first mixture comprising an initiator and a comminuted polyolefin at a temperature ranging from 160°C to 230°C to obtain a modified polyolefin having a melt flow index (MFI) ranging from 3 g/10 min to 70 g/10 min; (b) devulcanizing the waste synthetic rubber in presence of a devulcanizing agent to obtain synthetic rubber powder; and (c) extruding a second mixture comprising the modified polyolefin, at least one filler and the synthetic rubber powder at a temperature ranging from 160°C to 230°C to obtain recycled extrudates.
[0038] For the purpose of the present disclosure, the term "waste polyolefin" refers to the articles and/or shaped products made from one or more of recycled, non-recycled, and fresh polyolefin. The present disclosure is not limited by the shape, size and dimension of such articles and/or shaped products. In some embodiments, the waste polyolefin is a polyolefin article made from polypropylene, polyethylene, and mixtures thereof.
[0039] For the purpose of the present disclosure, the term "waste synthetic rubber" refers to shaped articles and/or shaped products made from one or more of recycled, non-recycled, and fresh synthetic rubber. The present disclosure is not limited by the shape, size and dimension of such articles and/or shaped products. In an embodiment, the waste synthetic rubber is a comminuted synthetic rubber articles made from one or more of nitrile rubber, butyl rubber, neoprene rubber, isoprene rubber, polybutadiene rubber and mixtures thereof.
[0040] For the purpose of the present disclosure, the term “comminution” refers to the reduction of particle size to small or minute particles, performed by one or more of shearing, shredding, grinding, and crushing. Such comminution is commonly performed by feeding waste polyolefin into the interface of counter-rotating intermeshing cutter members.
[0041] For the purpose of the present disclosure, the "mixing" is carried out using suitable mixer means such as, but not limited to, a stirrer or a mixer. Suitable stirring rate or rpm is known to persons skilled in the art and hence, the present disclosure is not limited by the same.
[0042] In an embodiment, the modified polyolefin of step (A) is obtained as follows:
(a1) grinding the waste polyolefin to obtain the comminuted polyolefin, wherein the comminuted polyolefin has a particle size ranging between 1 mm to 100 mm,
(a2) washing and drying the comminuted polyolefin in hot air at a temperature ranging between 80°C to 150°C,
(a3) mixing the initiator and the comminuted polyolefin of step (A2) to obtain the first mixture,
(a4) extruding the first mixture at temperature ranging between 160°C to 230°C to obtain the modified polyolefin having MFI ranging in between 3 g/10min to 70 g/10min, and
(a5) cooling the modified polyolefin at a temperature ranging between 20°C to 30°C followed by pelletizing the modified polyolefin.
[0043] In one embodiment, the following temporal sequence of steps is followed for recycling the waste polymeric material comprising a mixture of a waste polyolefin and a waste synthetic rubber: (a1)  (a2)  (a3)  (a4)  (a5)  (b)  (c).
[0044] Suitable means for grinding the waste polyolefin are well known to the person skilled in the art. For instance, a cutting mill may be employed for obtaining the comminuted polyolefin. The grinding is carried out at suitable rpm, for instance, ranging between 100 rpm to 5000 rpm, or 100 rpm to 3000 rpm, or 500 rpm to 3000 rpm, or 800 rpm to 200 rpm, to obtain the comminuted polyolefin.
[0045] In some embodiments, the waste polyolefin has a particle size ranging from 1 mm to 90 mm, or 1 mm to 60 mm, or 5 mm to 50 mm, or 5 mm to 30 mm.
[0046] Subsequently, the waste polyolefin having desired particle size is washed and dried in hot air at a temperature ranging from 80°C to 150°C. This is to ensure hygienic handling of the waste polyolefin for subsequent processing as well as to remove any dust particles.
[0047] Polyolefins generally being viscous in nature, their flowability can be improved by using the technique of controlled rheology. For this, suitable initiators are mixed before extrusion. Accordingly, in some embodiments, the waste polyolefin is mixed with the initiator to obtain the first mixture. Suitable initiators comprise of organic peroxides and/or hydroperoxides.
[0048] In some embodiments, the initiator comprises organic peroxide, hydroperoxide or mixtures thereof. In some embodiments, the initiator is selected from the group consisting of: tert-butyl peroxide, cumene hydroperoxide, pinane hydroperoxide, diisopropylphenyl hydroperoxide, dibenzoyl peroxide, dilauroyl peroxide, and diacetyl peroxide. In an embodiment, the initiator is tert-butyl peroxide, cumene hydroperoxide or mixtures thereof.
[0049] In some embodiments, the amount of the initiator in the first mixture is in the range of 250 ppm to 10000 ppm based on the total weight of the first mixture. In some embodiments, the amount is in the range of 250 ppm to 8000 ppm, or 250 ppm to 5000 ppm, or 250 ppm to 3000 ppm, or 500 ppm to 2000 ppm.
[0050] The first mixture is subjected to extrusion at a temperature ranging from 160°C to 230°C to obtain the modified polyolefin having MFI ranging from 3 g/10min to 70 g/10min. In some embodiments, reactive extrusion of the waste polyolefin with the initiator is carried out. Suitable extrusion means or extruders are well known to the person skilled in the art. For instance, the extruder may be a single screw extruder, co-rotating twin-screw extruder or a counter rotating twin-screw extruder. Further, the temperature range of 160°C to 230°C depicts the temperature profile prevalent in the extruder, for instance, across a feed zone to a die zone.
[0051] In some embodiments, the modified polyolefin has MFI ranging from 3 g/10 min to 70 g/10 min, or 3 g/10 min to 50 g/10 min, or 5 g/10 min to 50 g/10 min, or 10 g/10 min to 40 g/10 min. MFI is determined in accordance with ASTM D 1238.
[0052] In some embodiments, devulcanizing of the waste synthetic rubber is carried out at a temperature ranging from 50°C to 150°C. In some embodiments, temperature ranges from 50°C to 120°C, or 50°C to 100°C, or 60°C to 90°C.
[0053] It is well known to the persons skilled in the art that a spatial network of sulfur-cured elastomers has three types of chemical bonds: C-C, S-C, and S-S, i.e., carbon-carbon bonds, sulfur-carbon bonds and sulfur-sulfur bonds. Devulcanization is conducted by means of destruction of the inter-chain cross bonds S-C and S-S in the elastomer, which bonds are weaker than main-chain C-C bonds. Although, various methods exist for carrying out devulcanization, the present disclosure relies, for instance, on the Mechano-chemical devulcanization method described in The Current Status of Sulphur Vulcanization and Devulcanization Chemistry: Devulcanization by Joseph et.al., Rubber Science, 29(1): 62-100, 2016, the contents whereof is incorporated herein in its entirety by way of reference. In some embodiments, the devulcanizing agent is urea and/or its derivative. Non-limiting examples of the urea derivatives include diphenyl urea, and methyl urea.
[0054] In some embodiments, the waste synthetic rubber is first chopped into small pieces, for instance in a size ranging between 5 mm to 100 mm, or 5 mm to 50 mm, or 10 mm to 20 mm. The chopped waste synthetic rubber is then mixed with the devulcanizing agent in suitable amounts and process conditions described herein for a time duration ranging from 0.1 h to 2 h to obtain the synthetic rubber powder. In some embodiments, mixing is carried out at rpm ranging from 10 rpm to 200 rpm, or 10 rpm to 100 rpm, or 30 rpm to 80 rpm. In some embodiments, the synthetic rubber powder obtained after devulcanization has a particle size in the range of 100 microns to 10000 microns. In some embodiments, the particle size ranges from 100 microns to 5000 microns, or 100 microns to 3000 microns, or 100 microns to 1500 microns.
[0055] In some embodiments, the waste synthetic rubber is a synthetic rubber article made from one or more of nitrile rubber, butyl rubber, neoprene rubber, isoprene rubber, polybutadiene rubber and mixtures thereof. In some embodiments, the synthetic rubber article is made from one or more of nitrile rubber, and butyl rubber. In some embodiments, the synthetic rubber article is made from nitrile rubber. Non-limiting example of such an article includes a nitrile glove.
[0056] In some embodiments, the devulcanizing agent is added in an amount ranging from 1 wt.% to 25 wt.% based on total weight of the waste synthetic rubber. In some embodiments, the devulcanizing agent is added in an amount ranging from 1 wt.% to 20 wt.%, or 1 wt.% to 15 wt.%, or 1 wt.% to 10 wt.%.
[0057] In some embodiments, the second mixture is prepared by mixing the modified polyolefin, at least one filler and the synthetic rubber powder, as described herein. The mixing can be carried out for a time duration ranging between 0.1 h to 3 h, or 0.1 h to 2 h, or 0.1 h to 1 h.
[0058] In some embodiments, the amount of synthetic rubber powder in the second mixture is in the range of 3 wt.% to 60 wt.% based on the amount of modified polyolefin. In some embodiments, the synthetic rubber powder is added in an amount ranging from 3 wt.% to 50 wt.%, or 3 wt.% to 40 wt.%, or 4 wt.% to 30 wt.%.
[0059] Suitable fillers for the purposes of the present disclosure include: fibers and/or particulates. Examples of fillers include, but not limited to, metal fibers, metalized inorganic fibers, metalized synthetic fibers, glass fibers, polyester fibers, polyamide fibers, graphite fibers, carbon fibers, ceramic fibers, mineral fibers, basalt fibers, inorganic fibers, aramid fibers, natural fibers, kenaf fibers, jute fibers, flax fibers, hemp fibers, cellulosic fibers, sisal fibers, and coir fibers. Examples of particulates include, but not limited to, clay, kaolin, mica, wollastonite, silica, talc, titanium dioxide, and Portland cement.
[0060] In some embodiments, the filler is selected from the group consisting of: glass fibers, carbon fibers, aramid fibers, natural fibers, clay, kaolin, mica, wollastonite, silica, talc, titanium dioxide, Portland cement and mixtures thereof. In some embodiments, the filler is added in an amount ranging from 5 wt.% to 70 wt.% based on the amount of the modified polyolefin. In some embodiments, the filler is added in an amount ranging from 5 wt.% to 60 wt.%, or 5 wt.% to 50 wt.%, or 5 wt.% to 45 wt.%.
[0061] The second mixture is subjected to extrusion at a temperature ranging between 160°C to 230°C to obtain recycled extrudates. Suitable extrusion means or extruders that may used for the said purpose are well known to the person skilled in the art. For instance, the extruder may be a single screw extruder, co-rotating twin-screw extruder or a counter rotating twin-screw extruder. Herein, the temperature range of 160°C to 230°C depicts the temperature profile prevalent in the extruder, for instance, across a feed zone to a die zone.
[0062] In some embodiments, the recycled extrudates is subjected to the step of shaping to obtain desired articles. The present disclosure is not limited by the shape and size of such articles. In some embodiments, the shaping is carried out by subjecting the recycled extrudates to molding and/or casting methods.
[0063] In some embodiments, the waste polyolefin is a polyolefin article made from polypropylene, polyethylene, and mixtures thereof. In some embodiments, the waste synthetic rubber is a synthetic rubber article made from nitrile rubber, butyl rubber, neoprene rubber, isoprene rubber, polybutadiene rubber and mixtures thereof.
[0064] Another aspect of the present disclosure relates to a shaped article. In some embodiments, the shaped article is obtained by shaping the recycled extrudates obtained from the above process. Accordingly, the embodiments pertaining to the method as described above are applicable here as well.
[0065] The possible geometries of the shaped articles are essentially not subject to any restrictions. Further, fabrication of these shaped articles is possible, in principle, via any suitable procedure. In some embodiments, the shaping is carried out by subjecting the recycled extrudates to molding, casting or combinations thereof. Examples of the shaped article include table coasters, pavement bricks, tiles, and aesthetic products.
[0066] Further aspect of the present disclosure relates to a process for preparing the shaped article, as described hereinabove.
[0067] In some embodiments, the shaped article is obtained by shaping the recycled extrudates obtained from the above process. Accordingly, the embodiments pertaining to the method as described above are applicable here as well.
[0068] Advantageously, the present disclosure addresses the need of increasing polymeric wastes by providing the above-described economical process, which is easily scalable. The recycled extrudate obtained in accordance with the present disclosure has improved or acceptable properties as compared to non-recycled (or fresh) polymeric materials for deriving shaped articles therefrom. Further, since the polymeric waste is recycled in the present process and converted to various useful articles, the ever-increasing demand for such articles can easily be supplemented with this process.
[0069] While the foregoing description discloses various embodiments of the disclosure, other and further embodiments of the invention may be devised without departing from the basic scope of the disclosure. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

EXAMPLES
[0070] For the purpose of conducting experiments, Polypropylene article (WPP) was used as the waste polyolefin; Nitrile rubber gloves (WNG) was used as the waste synthetic rubber; Cumene hydroperoxide (CHP) and/or Tert-butyl peroxide (TBP) were used as the initiator; urea was used as the devulcanizing agent; Talc (particle size approx. 60 microns), Titanium dioxide (particle size approx. 40 microns) and/or Portland cement (particle size approx. 50 microns) were used as the filler.
[0071] Testing methods:
[0072] Density was determined as per ASTM D792. Moisture content was determined as per ASTM D6980. Compressive strength was determined as per ASTM D695. MFI was determined as per ASTM D1238.
[0073] Recycling of waste polymeric material
[0074] Collection and segregation of waste: A typical R&D setup was considered for determining the waste generation and subsequent collection for the purpose of experiments. WPP and WNG were collected separately from various labs in the R&D setup. Waste collection containers were used for segregation using simple plastics identification techniques.
[0075] Comminution and washing of WPP: WPP was ground into small flakes using cutting mill (SM 300 from M/s Retsch GMBH, Germany). The mill was equipped with 6-disc rotor with 18 replaceable and reversible hard metal cutting tips. Comminution was carried out at 1000 rpm for a duration of 5 to 10 minutes to obtain comminuted polypropylene waste. The comminuted polypropylene waste was washed with water to remove dust and hygiene handling. Subsequently, the comminuted polypropylene waste was dried in hot air oven at 105°C for 2 to 3 hours.
[0076] Controlled rheology of comminuted polypropylene waste: The comminuted polypropylene waste was mixed with the initiator in suitable amounts (details provided in Table 1 below) to obtain the first mixture. Prior to subjecting the first mixture to extrusion, mixing between the comminuted polypropylene waste and the initiator was carried out in a high-speed mixer for 5 to 20 min.
[0077] Extrusion: Extrusion was carried out in a co-rotating twin-screw extruder (obtained from M/s Boolani Engineering Corporation, Mumbai, India) having screw diameter of 30 mm, L/D of 48/1 and equipped with eight heating zones. The Temperature profile of the extruder ranged between 160°C to 230°C from the feed zone to the die zone. Feeder screw and extruder screw speeds were set at 10 rpm and 225 rpm, respectively. The extrudates obtained were cooled by passing it through a water bath (maintained at 25°C with continuous water circulation) and pelletized subsequently. Table 1 below summarizes the details of the modified polypropylene obtained using different initiators.
Table 1: Details of modified polypropylene obtained using different initiators
Sr. No. Sample Name WPP (g) Initiator (g, ppm) MFI (g/10min)
1 WPP 1000 0, 0 20.1
CHP as initiator
2 CWPP1 1000 0.5, 500 14.9
3 CWPP2 1000 1, 1000 31.6
4 CWPP3 1000 1.5, 1500 33.2
TBP as initiator
5 TWPP1 1000 0.5, 500 20.1
6 TWPP2 1000 1, 1000 17.9
7 TWPP3 1000 1.5, 1500 27.9

[0078] Devulcanization of WNG: WNGs were cut into small pieces (approx. 10 to 20 mm size) and then devulcanized (DWNG) with urea in rheomixer for converting WNG into devulcanized powder (DWNG) as per the Mechano-chemical devulcanization method detailed in The Current Status of Sulphur Vulcanization and Devulcanization Chemistry: Devulcanization by Joseph et.al., Rubber Science, 29(1): 62-100, 2016. The process parameters for devulcanization are provided in Table 2 below.
Table 2: Process parameters for devulcanization
Description Value
Urea 10 wt.%
Temperature 80°C
RPM 50
Duration 0.5 h
Particle size of synthetic rubber powder 0.1 mm to 1 mm

[0079] Extrusion and shaping: CWPP (refer Table 1) was mixed with DWNG in a high-speed mixer for 5 to 20 min and then fed into the extruder through hopper. Extrusion was performed in a co-rotating twin-screw extruder (M/s Boolani Engineering Corporation, Mumbai, India) having screw diameter of 30 mm, L/D of 48/1 and equipped with eight heating zones. The Temperature profile of the extruder ranged between 160°C to 230°C from the feed zone to the die zone. Feeder screw and extruder screw speeds were set at 10 rpm and 225 rpm, respectively. The recycled extrudate was collected, in the molten form, in bricks making mold having dimension of 170 mm x 170 mm x 60 mm, made of aluminum and having a thickness of 1 mm. The mold was cooled to obtain bricks made of waste polymeric material.
[0080] Several bricks were made as per formulations mentioned in Examples 1 to 24 (below) and compared with non-recycled (or fresh) polypropylene and commercial bricks.
[0081] Examples 1-10:
[0082] Examples 1-10 deal with the formulations, wherein a model polymer (MPP12, fresh polypropylene) was added with DWNG and filler (talc) to understand the effect of additions on the density of the prepared material. Prepared compositions and obtained density values are listed in Table 3.
Table 3: Details of the compositions and density thereof
Sr. No. Example MPP12
(g) DWNG
(g) Talc
(g) Density
(g/cc)
1 Example 1 1000 - - 0.86
2 Example 2 1000 100 - 0.85
3 Example 3 1000 200 - 0.87
4 Example 4 1000 300 - 0.86
5 Example 5 1000 100 100 0.95
6 Example 6 1000 200 100 0.93
7 Example 7 1000 300 100 1.00
8 Example 8 1000 100 200 1.23
9 Example 9 1000 200 200 1.04
10 Example 10 1000 300 200 1.02

[0083] Examples 11-17
[0084] Examples 11-17 deal with the formulations, wherein MPP12 was added with DWNG and higher concentration of filler (talc) to understand the effect of additions on the density of the prepared material. Prepared compositions and the obtained density values are listed in Table 4 below.
Table 4: Details of the compositions and density thereof
Sr. No. Example MPP12
(g) DWNG
(g Talc
(g Density
(g/cc)
1 Example 1 1000 - - 0.86
2 Example 11 1000 - 500 1.04
3 Example 12 1000 - 750 1.14
4 Example 13 1000 - 1000 1.22
5 Example 14 1000 100 1000 1.18
6 Example 15 1000 200 1000 1.12
7 Example 16 1000 300 1000 1.16
8 Example 17 1000 400 1100 1.09

[0085] Examples 18 and 19
[0086] Examples 18 and 19 deal with the formulations wherein MPP12 was added with DWNG and filler (titanium dioxide) to understand the effect of additions on the density of the prepared material. Prepared compositions and the obtained density values are listed in Table 5 below.
Table 5: Details of the compositions and density thereof
Sr. No. Example MPP12
(g) DWNG
(g) Titanium dioxide
(g) Density
(g/cc)
1 Example 1 1000 - - 0.86
2 Example 18 1000 300 1000 1.19
3 Example 19 1000 400 1100 1.16

[0087] Examples 20 and 21
[0088] Examples 20 and 21 deal with the formulations, wherein MPP12 was added with DWNG and filler (cement) to understand the effect of additions on the density of the prepared material. Prepared compositions and the obtained density values are listed in Table 6 below.
Table 6: Details of the compositions and density thereof
Sr. No. Example MPP12
(g) DWNG
(g) Portland cement
(g) Density
(g/cc)
1 Example 1 1000 - - 0.86
2 Example 20 1000 300 1000 1.20
3 Example 21 1000 400 1100 1.21

[0089] Examples 22-24
[0090] Examples 22 to 24 deal with the formulations, wherein CWPP2 was added with DWNG and filler (Portland cement) to understand the effect of additions on the density of the prepared material. Prepared compositions and the obtained density values are listed in Table 7 below.
Table 7: Details of the compositions and density thereof
Example CWPP2
(g) DWNG
(g) Portland cement (g) Density
(g/cc) Moisture Content (%) Compressive Strength (MPa)
Example 22 1000 - - 0.86 0.1 37.0
Example 23 1000 300 1000 1.23 0.2 23.0
Example 24 1000 400 1100 1.22 0.3 24.0
Commercial Brick - - - 1.9 6.0 12.2

[0091] In order for a material to be used as a brick, it is essential that its density be more than 1 g/cc. Since Example 22 (brick made solely of recycled waste polyolefin) has a density less than 1 g/cc, it was found not to be suitable as a brick. The brick made from recycled extrudate (Examples 23 and 24) in accordance with the present disclosure is comparable with a commercially available brick. In fact, the compressive strength of the brick made from recycled extrudates was found to be twice than that of the commercially available brick.
[0092] Form the foregoing, it is evident that the recycled extrudate of the present disclosure has improved properties when compared to non-recycled (or fresh) polymeric materials for deriving shaped articles therefrom.

ADVANTAGES
[0093] The present disclosure relates to a process for recycling a waste polymeric material including a mixture of a waste polyolefin and a waste synthetic rubber, which is economical, scalable and technologically feasible.
[0094] The present disclosure provides recycled extrudates/materials having comparable or improved properties when compared to non-recycled (or fresh) polymeric materials for deriving shaped articles therefrom, while being economical.
, Claims:1. A process for recycling a waste polymeric material comprising a mixture of at least one waste polyolefin and at least one waste synthetic rubber, said process comprising the steps of:
(a) extruding a first mixture comprising an initiator and a comminuted polyolefin at a temperature ranging from 160°C to 230°C to obtain a modified polyolefin having a melt flow index (MFI) ranging from 3 g/10 min to 70 g/10 min;
(b) devulcanizing the waste synthetic rubber in presence of a devulcanizing agent to obtain a synthetic rubber powder; and
(c) extruding a second mixture comprising the modified polyolefin, at least one filler and the synthetic rubber powder at a temperature ranging from 160°C to 230°C to obtain recycled extrudates.
2. The process as claimed in claim 1, wherein the step (a) comprises the following sub-steps:
(a1) grinding the waste polyolefin to obtain the comminuted polyolefin, wherein the comminuted polyolefin has a particle size ranging from 1 mm to 100 mm;
(a2) washing and drying the comminuted polyolefin in hot air at a temperature ranging from 80°C to 150°C;
(a3) mixing the initiator and the comminuted polyolefin of step (a2) to obtain the first mixture;
(a4) extruding the first mixture at temperature ranging from 160°C to 230°C to obtain the modified polyolefin having the melt flow index ranging from 3 g/10 min to 70 g/10 min; and
(a5) cooling the modified polyolefin at a temperature ranging from 20°C to 30°C followed by pelletizing the modified polyolefin.
3. The process as claimed in claim 1 or 2, wherein the initiator comprises organic peroxide, and/or hydroperoxide selected from the group consisting of: tert-butyl peroxide, cumene hydroperoxide, pinane hydroperoxide, diisopropylphenyl hydroperoxide, dibenzoyl peroxide, dilauroyl peroxide, and diacetyl peroxide.
4. The process as claimed in one or more of claims 1 to 3, wherein the devulcanizing agent comprises urea and/or its derivative.
5. The process as claimed in one or more of claims 1 to 4, wherein the devulcanizing agent is added in an amount ranging from 1 wt.% to 25 wt.% based on the total weight of the waste synthetic rubber.
6. The process as claimed in one or more of claims 1 to 5, wherein devulcanizing is carried out at a temperature ranging from 50°C to 150°C.
7. The process as claimed in one or more of claims 1 to 6, wherein the filler is selected from the group consisting of: glass fibers, carbon fibers, aramid fibers, natural fibers, clay, kaolin, mica, wollastonite, silica, talc, titanium dioxide, and Portland cement.
8. The process as claimed in one or more of claims 1 to 7, wherein the filler is added in an amount ranging from 5 wt.% to 70 wt.% based on the amount of the modified polyolefin.
9. The process as claimed in one or more of claims 1 to 8, wherein the amount of synthetic rubber powder in the second mixture is in the range of 3 wt.% to 60 wt.% based on the amount of modified polyolefin.
10. The process as claimed in one or more of claims 1 to 9, wherein the waste polyolefin is a polyolefin article made from polypropylene, polyethylene, and mixtures thereof.
11. The process as claimed in one or more of claims 1 to 10, wherein the waste synthetic rubber is a synthetic rubber article made from nitrile rubber, butyl rubber, neoprene rubber, isoprene rubber, polybutadiene rubber and mixtures thereof.
12. A shaped article obtained by shaping the recycled extrudates obtained in accordance with the process as claimed in one or more of claims 1-11.
13. The shaped article as claimed in claim 12, wherein the shaping is carried out by subjecting the recycled extrudates to molding and/or casting methods.
14. The shaped article as claimed in claim 12 or 13, wherein the shaped article is selected from table coasters, pavement bricks, tiles, and aesthetic products.
15. A process for preparing a shaped article, said process comprising the step of shaping the recycled extrudates obtained from the process as claimed in one or more of claims 1-11.