CLIAMS:1. A Ziegler-Natta catalyst system comprising i. a pro-catalyst comprising magnesium alkoxide based support and at least one transition metal; and ii. at least one external electron donor selected from the group consisting of substituted silanediyl diacetate, trialkyl borate and tetraalkoxysilane.

2. The catalyst system as claimed in claim 1, wherein the magnesium alkoxide is spheroidal magnesium alkoxide.

3. The catalyst system as claimed in claim 1, wherein the Ziegler-Natta catalyst system is further based on a silica support and the ratio of magnesium to silica ranges from 1:10 to 1:30.

4. The catalyst system as claimed in claim 1, wherein the Ziegler-Natta catalyst system is further based on silica, said catalyst system comprising at least one external electron donor selected from the group consisting of trialkyl borate and tetraalkoxy silane.

5. The catalyst system as claimed in claim 1, wherein

- the substituted silanediyl diacetate is at least one selected from the group consisting of diethyl-2,2’-(dimethylsilanediyl)diacetate; diethyl-2,2’-(phenyl(methyl)silanediyl)diacetate and diethyl-2,2’-(diisopropylsilanediyl)diacetate;
- the trialkyl borate is at least one selected from the group consisting of triethyl borate and trimethyl borate; and
- the tetraalkoxy silane is at least one selected from the group consisting of tetramethoxysilne, tetraethoxy silane, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, diethyldiethoxysilane, diisobutyldimethoxysilane.

6. The catalyst system as claimed in claim 1, wherein the transition metal is selected from the group consisting of titanium (Ti), Zirconium (Zr) and Hafnium (Hf) and the molar ratio of the transition metal to the external donor ranges from 1:2 to 1:50.

7. The catalyst system as claimed in claim 1, further comprises at least one organo-aluminium metal compound as a co-catalyst, wherein the ratio of the organo-aluminium compound to the external electron donor ranges from 2:1 to 50:1.

8. The catalyst system as claimed in claim 1, is used for polymerizing olefins, wherein polymerizing olefins comprises a. mixing at least one external electron donor with (i) a pro-catalyst comprising magnesium alkoxide and optionally, silica as a base support, and at least one transition metal; and (ii) at least one co-catalyst to obtain a Ziegler-Natta catalyst system; b. adding the Ziegler-Natta catalyst system to a reaction mass containing at least one olefin; c. polymerizing the olefin optionally, in the presence of chain transfer agent to obtain a polyolefin having molecular weight in the range of 1.0 million g/mol to 14 million g/mol, bulk density in the range of 0.3 to 0.5 g/cc, preferably 0.32 to 0.41 g/cc; wherein the olefin is ethylene, the polyolefin is polyethylene and the chain transfer agent is hydrogen.

9. The catalyst system as claimed in claim 9, wherein the method step of polymerizing is carried out at a temperature ranging from 50 to 90 oC, preferably 70 oC and at an olefin pressure ranging from 5 Kg/cm2 to 15 Kg/cm2, preferably 6 Kg/cm2 for a time period ranging from 10 minutes to 120 minutes, preferably 60 minutes.

10. A process for preparing the Ziegler-Natta catalyst system as claimed in claim 1, said process comprising mixing said external electron donor with (i) a pro-catalyst comprising magnesium alkoxide and optionally, silica as a base, and at least one transition metal; and (ii) at least one co-catalyst before using said catalyst system for polymerizing olefins. ,TagSPECI:FIELD:
The invention disclosed in the present disclosure relates to external electron donors for Ziegler-Natta catalyst systems to produce polyethylene. Particularly, the invention disclosed in the present disclosure relates to external electron donors for Ziegler-Natta catalyst systems which are based on magnesium alkoxide and/or silica for the production of Ultra High Molecular Weight Polyethylene.

BACKGROUND:
An electron donor in a Ziegler-Natta catalyst system has a significant impact on the properties such as molecular weight, molecular weight distribution (MWD) and intrinsic viscosity of the resulting polymer. The electron donor also affects the catalyst activity in polymerization reactions. Therefore, efforts are made to arrive at a catalyst system that comprises an electron donor which upon using provides polymer or polyolefin having desired properties such as ultra-high molecular weight.

A Ziegler-Natta catalyst system suggested in US20040242409 and US20020045537 contain boron compounds as solubilizing or clipping agents or as an internal donor for the preparation of polyethylene and UHMWPE.

US8268945 suggests a Ziegler-Natta catalyst system containing an organic silicon compound for ethylene polymerization.

WO2012139897 suggests a Ziegler-Natta catalyst system modified with ether and succinate and containing silicon alkoxides as external electron donor for the preparation of polyethylene.

EP0267794 and EP0195497 suggest Ziegler-Natta catalyst systems containing tetraethoxy silane as an external donor, whereas WO2011000692 and EP0195497 suggest Ziegler-Natta catalyst systems containing triethyl borate as an internal donor.
WO2010120973 suggests a Ziegler-Natta catalyst system containing silyl glutarates such as diethyl-2,2’-(dimethylsilanediyl)diacetate; diethyl-2,2’-(diethylsilanediyl)diacetate; diethyl-2,2’-(dipropylsilanediyl)diacetate; diethyl-2,2’-(diisopropylsilanediyl)diacetate diethyl-2,2’-(dibutylsilanediyl)diacetate; diethyl-2,2’-(diisobutylsilanediyl)diacetate as internal donors for polymerization of olefins.
The drawback associated with the suggested Ziegler-Natta catalyst systems modified with internal electron donors, is that they are costly as compared to Ziegler-Natta catalyst systems modified with external electron donors for the reason that the process for the preparation of Ziegler-Natta catalyst systems modified with internal electron donors require particular process, processing parameters and equipment. Further, polyolefins obtained using these catalyst systems including catalyst systems comprising silyl glutarates as internal donors, are more likely to possess unacceptable morphological properties as these catalyst systems are incapable of controlling the morphological properties of polyolefins. Still further, the drawback of these suggested catalyst systems is that they are effective at high temperature conditions thereby, making use of these catalysts energy inefficient.
Therefore, there is a felt need for Ziegler-Natta catalyst systems which are cost effective and energy efficient as compared to the suggested catalyst systems and capable of controlling morphological properties of polyolefins effectively.
OBJECTS:
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide Ziegler-Natta catalyst systems for polymerizing olefins.
Another object of the present disclosure is to provide Ziegler-Natta catalyst systems capable of controlling morphological properties of polyolefins effectively.
Still another object of the present disclosure is to provide Ziegler-Natta catalyst systems which are easy to prepare.
Yet another object of the present disclosure is to provide Ziegler-Natta catalyst systems which are capable of providing ultrahigh molecular weight polyolefins.
Other objects of the present invention will be more apparent to a person skilled in the art from the description provided herein after.

SUMMARY:
Accordingly to overcome the drawbacks associated with these suggested catalyst systems the invention disclosed in the present disclosure provides a Ziegler-Natta catalyst system comprising at least one external electron donor. The external donor used for preparing the Ziegler-Natta catalyst system is at least one compound selected from the group consisting of trialkyl borate substituted silanediyl diacetate and tetraalkoxy silane. The pro-catalyst of the Ziegler-Natta catalyst system comprising at least one transition metal is based either on magnesium alkoxide or magnesium alkoxide and silica.
In contrast to the teachings of an article titled “Preparation of ultra-high molecular weight polyethylene with MgCl2/TiCl4 catalyst: effect of internal and external donor on molecular weight and molecular weight distribution” published in Polym. Bull. 2011 (66), 627-635, the invention disclosed in the present disclosure shows that the application of external electron donors results into polyolefin having molecular weight (MW) of polyethylene up to 14 million g/mol. Further, the Ziegler-Natta catalyst system disclosed in the present disclosure is capable of synthesizing ultrahigh molecular weight polyolefin particularly, ultrahigh molecular weight polyethylene (UHMWPE) having intrinsic viscosity upto 47.0 dl/g.

The invention disclosed in the present disclosure provides an easy and efficient approach through external modification of the catalyst system to produce polyethylene having molecular weight (MW) up to 14 million g/mol and narrow molecular weight distribution. The externally modified catalyst systems of the present disclosure are economically more advantageous as compared to internally modified catalyst systems since, the process for the preparation of Ziegler-Natta catalyst systems modified with internal electron donors require particular process, processing parameters and equipment.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING/S:
Figure 1 illustrates- SEM images of UHMWPE
(A) UHMWPE synthesized using donor free system;
(B) UHMWPE synthesized using DSD-1;
(C) UHMWPE synthesized using DSD-2; and
(D) UHMWPE synthesized using DSD-3.

DETAILED DESCRIPTION:
The invention disclosed in the present disclosure provides Ziegler-Natta catalyst systems in which the pro-catalyst comprising at least one transition metal is based on magnesium alkoxide and/or silica and is externally modified by external electron donors. Examples of the transition metal includes group IV metals such as titanium (Ti), Zirconium (Zr), Hafnium (Hf) and the like and aluminum metal compound, particularly organo-aluminium compound as a co-catalyst. The amount of aluminium metal compound to be used as a co-catalyst is such that the ratio of the aluminium metal compound to the external electron donor is maintained in the range of 2:1 to 50:1.
Further, the ratio of the transition to the external electron donor in the Ziegler-Natta catalyst of the present disclosure, ranges from 1:2 to 1:50.

The external electron donors using which the Ziegler-Natta catalyst system of the invention disclosed in the present disclosure is modified comprises substituted silanediyl diacetates such as diethyl-2,2’-(dimethylsilanediyl)diacetate; diethyl-2,2’-(phenyl(methyl)silanediyl)diacetate; diethyl-2,2’-(diisopropylsilanediyl)diacetate and combinations thereof; trialkyl borates such as triethyl borate, trimethyl borate and combination thereof; and tetraalkoxysilanes such as tetramethoxysilne, tetraethoxy silane, cyclohexylmethyldimethoxysilane, dicyclopentyldimethoxysilane, diethyldiethoxysilane, diisobutyldimethoxysilane and combinations thereof.

Though the magnesium alkoxide in the Ziegler-Natta catalyst system of the invention disclosed in the present disclosure can be of any shape it is observed that the desired results in terms of properties of resulting polyolefin and the activity of the catalyst was obtained for the spheroidal magnesium alkoxide, since, the spheroidal magnesium alkoxide effectively controls the shape and activity of the catalyst during the polymerization reactions.

It is also observed that the Ziegler-Natta catalyst system comprising magnesium alkoxide and silica as support or base provides desired results when trialkyl borate and/or tetraalkoxy silane are/is used as an external electron donor. Further, when the Ziegler-Natta catalyst system comprising only magnesium alkoxide as a base provides desired results when substituted silanediyl diacetate is used as an external electron donor.

Still further, the Ziegler-Natta catalyst system comprising magnesium alkoxide and silica as support or base and substituted silanediyl diacetate as an external electron donor; and the Ziegler-Natta catalyst system comprising magnesium alkoxide as a support or base and trialkyl borate and/or tetraalkoxy silane as an external electron donor may also provide acceptable results.
The ratio of magnesium to silica also has an effect on the activity of the catalyst and therefore the ratio of magnesium to silica is optimized to be in the range of 1:10 to 1:30

The Ziegler-Natta catalyst systems modified externally using the external electron donors is useful for polymerizing olefins.

The invention disclosed in the present disclosure also provides a process for preparing a polyolefin. In the first step, at least one external electron donor is mixed with a pro-catalyst comprising magnesium alkoxide and/or silica as a base and at least one transition metal; and at least one co-catalyst to obtain a Ziegler-Natta catalyst system.

The Ziegler-Natta catalyst system is added to a reaction mass containing at least one olefin to obtain a reaction mixture. The olefin is then subjected to polymerization reaction at a temperature ranging from 50 to 90 oC, particularly 70 oC and at a pressure from 5 Kg/cm2 to 15 Kg/cm2, particularly 6 Kg/cm2 for a time period ranging from 10 minutes to 120 minutes, particularly 60 minutes to obtain a polyolefin. The polymerization reaction may be carried out in the presence of chain transfer agent such as hydrogen.

The polyolefin obtained as a result of using the external electron donors of the invention disclosed in the present disclosure, possesses ultrahigh molecular weight ranging from 1.0 million g/mol to 14 million g/mol, bulk density in the range of 0.3 to 0.5 g/cc. The polyolefin obtained as a result of using the external electron donors of the present invention particularly has a bulk density in the range of 0.32 to 0.41 g/cc.
Particularly, the Ziegler-Natta catalyst system of the invention disclosed in the present disclosure is applied for polymerizing ethylene to obtain ultrahigh molecular weight polyethylene (UHMWPE).
The present disclosure also provides a process for preparing the Ziegler-Natta catalyst system which involves a step of mixing the external electron donor with a pro-catalyst comprising magnesium alkoxide and optionally, silica as a base, and at least one transition metal and a co-catalyst.
The invention disclosed in the present disclosure will now be described in light of the following non-limiting examples.

Example 1: Ethylene polymerization using substituted silanediyl diacetate compounds as external electron donors in Ziegler Natta (ZN) catalyst system

The ZN monoester (Ethyl benzoate as internal donor for MgCl2 supported Ti based catalyst) pro-catalyst based on spheroidal magnesium alkoxide precursor was modified by the application of substituted silanediyl diacetate compounds as external electron donors and used for the polymerization of ethylene to obtain ultrahigh molecular weight polyethylene.

Ethylene polymerization experiments were performed at the ratio of Al/Ti=250 and Al/ED=5 using substituted silanediyl diacetate compounds as external electron donors to investigate the effect of donor on the polymer properties. For comparison, the experiments were carried out with p-ethoxyethyl benzoate (PEEB) as an external electron donor and without external electron donor i.e. ‘donor free system’ in the same polymerization conditions. The results are provided herein table 1.
Table 1: Characterization data of ZN catalyst comprising substituted silanediyl diacetate as an external donor and polyethylene obtained using the ZN catalyst

Key: ED: External electron donor; BD: Bulk density; Xc:% crystallization; a polymerization without
hydrogen; bSolution viscosity method using Ubbelohde viscometer; [?]in Intrinsic viscosity

DSD1 is Diethyl 2,2'-(dimethylsilanediyl)diacetate;

DSD2 is Diethyl 2,2'-(phenyl(methyl)silanediyl)diacetate; and

DSD3 is Diethyl 2,2'-(diisopropylsilanediyl)diacetate

The ethylene polymerization using the catalyst system of the present invention, the molecule weights have been found in the range of 6.0 to 6.8 million g/mol. As compared to ‘donor free’ system molecular weight has been increased up to four times. It is evident that the substituted silanediyl diacetate compounds used as external electron donors exert a significant effect on the molecular weight of the polymer.
Furthermore, improved catalyst systems reflect less number of active centers present in the catalyst at the time of polymerization as compared to ‘donor free’ system, since the former has less polymer productivity. However, at the same time it prevents the chain termination of the growing polymer chain in a far better way as compared to ‘donor free’ system that in-turn significantly increases the molecular weight. It indicates that modified catalyst system has lesser tendency for formation of a-oligomers such as 1-butene which are accountable for chain termination of growing polymer chain. Interestingly, in case of DSD3 the presence of bulkier isopropyl substitution has a significant effect that not only prevents the chain termination at the active center but also allows the presence of abundant number of active sites. This is reflected in terms of increased productivity of the polymer as well as molecular weight as compared to DSD1 and DSD2. Moreover, an increase in % crystallinity measured by DSC analysis shows that UHMWPE synthesized by improved catalyst system has a less degree of entanglements as compared to ‘donor free’ system. The polymer resin synthesized by modified catalyst system shows a high bulk density in the range of 0.33 to 0.38 g/cc. The average particle size of polymer resin decreases as the bulkiness of donor increases its shows Average Particle Size (APS) of polymer resin can be altered by the use of different electron donors. The morphological images of polymer resins are showed in Fig. 1.

Example 2: Ethylene polymerization using substituted silanediyl diacetate compounds as external electron donors in Ziegler Natta(ZN) catalyst system in the presence of chain transfer agent (hydrogen)
A set of experiments was carried out in presence of hydrogen to analyze the effect of chain transfer agent on the properties of the end polymer resins using DSD1 as an external electron donor. The results are provided in Table 2

Table 2: Characterization data of ZN catalyst comprising DSD1 as an external donor and polyethylene obtained using the ZN catalyst in the presence of chain transfer agent (hydrogen)

Key:aSolution viscosity method using Ubbelohde viscometer; ED: External electron donor; BD: Bulk
density; Xc:% crystallization; [?]in Intrinsic viscosity

The rate of chain termination at the active center increases with an increase in concentration of chain transfer agent which reflects in decreased molecular weight of polyethylene. It shows that improved catalyst system is capable to produce HDPE in same conditions in presence of chain transfer agent with a less variation in the % crystallinity of the polymer.

Example 3: Ethylene polymerization using triethyl borate as an external electron donor

The ZN monoester procatalyst based on spheroidal magnesium alkoxide precursor was modified by using triethyl borate as an external electron donor. The ethylene polymerization reactions were carried at the ratio of Al/Ti=250 and Al/ED=20-40. The results are provided in Table 3.

Table 3: Characterization data of ZN catalyst comprising triethyl borate as an external donor and polyethylene obtained using the ZN catalyst

Key: ED: External electron donor; BD: Bulk density; Xc:% crystallization; a polymerization without
hydrogen; bSolution viscosity method using Ubbelohde viscometer; [?]in Intrinsic viscosity

The catalyst system comprising triethyl borate as an external electron donor has significant effect on the molecular weight. The synthesized resins have high polymer density. Moreover, the bulk density of UHMWPE can be altered by variation in donor concentration without changing the morphology of the polymer resins.

Example 4: Ethylene polymerization using triethyl borate as external electron donors in Ziegler Natta(ZN) catalyst system in the presence of chain transfer agent (hydrogen)

The effect of chain transfer agent on the properties of the end polymer resins in the presence of triethoxy borate is also evaluated by conducting a set of experiments at Al/Ti=250 and Al/D=30. The results are provided in Table 4.

Table 4: Characterization data of ZN catalyst comprising triethyl borate as an external donor and polyethylene obtained using the ZN catalyst in the presence of chain transfer agent (hydrogen)

Key:aSolution viscosity method using Ubbelohde viscometer; ED: External electron donor; BD: Bulk
density; Xc:% crystallization; [?]in Intrinsic viscosity

The presence of chain transfer agent enhances the polymer chain termination that evident from the decreased molecular weight of polyethylene. This demonstrates that the modified catalyst system using triethyl borate is able to synthesize HDPE in same conditions in presence of chain transfer agent.

Example 5: Ethylene polymerization using triethyl borate as an external electron donor, wherein the ZN is diester (diethyl phthalate as internal donor for MgCl2 supported Ti based catalyst) catalyst system

The ZN diester procatalyst based on spheroidal magnesium alkoxide precursor was modified by the application of triethoxy borate as external electron donors. The results are provided in Table 5

Table 5: Characterization data of ZN catalyst comprising triethyl borate as an external donor and polyethylene obtained using the ZN catalyst

Key: ED: External electron donor; BD: Bulk density; Xc:% crystallization; a polymerization without
hydrogen; bSolution viscosity method using Ubbelohde viscometer; [?]in Intrinsic viscosity

The modified diester catalyst system by triethoxy borate synthesizes UHMWPE of 8 million g/mol molecular weight with improved activity and high bulk density.

Example 6: Polymerization reactions
The polymerizations were performed in hexane medium with triethylaluminium as co-catalyst (Al/Ti=100). To investigate the effect of temperature on productivity and molecular weight of the polymer resins a systematic temperature study has been carried out. The study reveals that catalyst activity is improved with increase in polymerization temperature, whereas the molecular weight decreases. An advantage of the catalyst of the present invention is that the catalyst performs at low temperature, which provides an energy efficient process. The polymer resins synthesized by catalyst system shows high bulk density that found in the range of 0.40 to 0.46 g/cc and also shows narrow particle size distribution. The results are provided in tables 6 to 10.

Table 6: Ethylene polymerization using Si-Mg catalyst at different temperature in hexane medium

Key: ED: External electron donor; BD: Bulk density; Xc:% crystallization; bSolution viscosity method
using Ubbelohde viscometer
Example 6a:

The effect of chain transfer agent (hydrogen) was determined that shows that modified catalyst system is capable to produce moderate to ultrahigh molecular weight polyethylene in same conditions in presence of chain transfer agent. The results are provided in table 7

Table 7: The effect of chain transfer agent in Si-Mg-Ti catalyst for ethylene polymerization at 70 ºC

Key: Solution viscosity method using Ubbelohde viscometer; BD: Bulk density; Xc:%
crystallization

Example 6b:

The effect of organic modifier (silicon tetraethoxide) as an external donor with Si-Mg-Ti was carried out at 70 ºC. The polymerization were carried at the ratio of Al/Ti=100 and Al/ED=2 to 20. (Table 10) A significant effect on the molecular weight has observed and polymer resin with molecular weight in range of 5-11 million g/mol was obtained. The bulk density of UHMWPE has been decreases as donor concentration increases. The results are provided in table 8.

Table 8. Effect of silicon tetraethoxide on ethylene polymerization using Si-Mg-Ti
catalyst at 70 ºC

Key: Solution viscosity method using Ubbelohde viscometer; BD: Bulk density; Xc:%
Crystallization

Example 6c:

Si-Mg-Ti catalyst was externally modified by triethoxy borate. The polymerization were carried at the ratio of Al/Ti=100 and Al/ED=10 to 40. The catalyst system comprising triethoxy borate has significant effect on the molecular weight and shows molecular weight in range of 5-12 million g/mol. The bulk density of UHMWPE has been decreases as donor concentration increases however, morphology of polymer retain similar. The results are provided in table 9.

Table 9: Effect of borate donors on ethylene polymerization using Si-Mg-Ti catalyst at 70 ºC

Key: Solution viscosity method using Ubbelohde viscometer; BD: Bulk density; Xc:% crystallization

The modified Si-Mg-Ti catalyst system with borate donor has much lesser tendency for formation of a-oligomers such as 1-butene as compared that of Mg-Ti catalyst system which results in increase in the molecular weight of polyethylene up to 11.7 million g/mol.

Example 6d:
A set of experiments was carried out in presence of hydrogen to analyze the effect of chain transfer agent on the properties of the end polymer resins using triethoxy borate as an external electron donor. It shows that modified catalyst system is capable to produce moderate to ultra high MW polyethylene. The results are provided in Table 10.

Table 10: The effect of chain transfer agent in borate modified Si-Mg-Ti catalyst for ethylene polymerization at 70 ºC

Key: Solution viscosity method using Ubbelohde viscometer; BD: Bulk density; Xc:%
crystallization

ADVANTAGES OF THE INVENTION DISCLOSED IN THE PRESENT DISCLOSURE:
The use of improved spheroidal magnesium alkoxide precursor results in the production of polyolefins, mainly polyethylene having improved properties.

The invention disclosed in the present disclosure provides a direct process for catalyst modification.

The invention disclosed in the present disclosure involves external modification of catalyst system which is cost effective as compared to internal modification of catalyst system.

The invention disclosed in the present disclosure provides polyethylene with a molecular weight in the range of 1- 14 million g/mol by means of external donor modification and chain transfer agent.

The invention disclosed in the present disclosure also provides improved morphological controlled polyethylene resin.

The invention disclosed in the present disclosure provides a catalyst that performs at low temperature, making the polymerization process energy efficient.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.