阅读说明：本技术 一种废旧塑料再生工艺 (Waste plastic regeneration process ) 是由 段伟 段朋朋 段志豪 于 2021-08-23 设计创作，主要内容包括：本发明公开了一种废旧塑料再生工艺,属于废旧塑料再生技术领域。且该工艺包括以下步骤：一、将废旧塑料粉碎、过筛,碱液浸泡,清洗,烘干,得废旧塑料颗粒；二、将废旧塑料颗粒和助剂在110-120℃下搅拌混合均匀,再经挤出造粒,得废旧塑料再生塑料。且本发明在废旧塑料再生工艺过程中添加了助剂,从而达到解决废旧塑料再生料质脆、韧性差,耐磨性差的技术问题,所述助剂是由改性蓖麻油、二羟基POSS、含羧基二元异氰酸酯和端羟基聚醚改性聚二甲氧基硅氧烷逐步反应获得的,使其分子中含有POSS结构、直链硅氧烷链、聚醚链,使该助剂与废旧塑料具有优异的相容性,其的加入提高了废旧塑料颗粒的韧性、强度和耐磨性。(The invention discloses a waste plastic regeneration process, and belongs to the technical field of waste plastic regeneration. And the process comprises the following steps: firstly, crushing and sieving waste plastics, soaking in alkali liquor, cleaning and drying to obtain waste plastic particles; and secondly, uniformly stirring and mixing the waste plastic particles and the auxiliary agent at the temperature of 110-120 ℃, and then extruding and granulating to obtain the waste plastic regenerated plastic. The auxiliary agent is obtained by gradually reacting modified castor oil, dihydroxy POSS, carboxyl-containing diisocyanate and hydroxyl-terminated polyether modified polydimethoxysiloxane, so that the molecule of the auxiliary agent contains a POSS structure, a linear siloxane chain and a polyether chain, the auxiliary agent and the waste plastic have excellent compatibility, and the addition of the auxiliary agent improves the toughness, strength and wear resistance of waste plastic particles.)

1. A waste plastic regeneration process is characterized in that: the method comprises the following steps:

firstly, crushing and sieving waste plastics, soaking in alkali liquor, cleaning and drying to obtain waste plastic particles;

secondly, stirring and mixing the waste plastic particles and the auxiliary agent uniformly at the temperature of 110-120 ℃, and then extruding and granulating to obtain the waste plastic regenerated plastic;

the auxiliary agent is prepared by the following steps:

s1, mixing the modified castor oil, the dihydroxy POSS and the N, N-dimethylformamide, adding p-toluenesulfonic acid, reacting at 75 ℃ for 3 hours, performing rotary evaporation, and performing vacuum drying to obtain an intermediate 1;

s2, mixing the intermediate 1, the carboxyl-containing diisocyanate and the anhydrous dichloromethane, heating to 80 ℃, reacting for 3 hours, adding the hydroxyl polyether modified polydimethoxysiloxane, continuing to react for 6 hours, decompressing, steaming, and drying in vacuum to obtain the auxiliary agent.

2. The process for recycling waste plastics according to claim 1, characterized in that: and in the first step, the sieving is to pass through a 70-mesh sieve.

3. The process for recycling waste plastics according to claim 1, characterized in that: in the first step, the soaking time is 30-60 min.

4. The process for recycling waste plastics according to claim 1, characterized in that: the drying temperature in the first step is 30-50 ℃.

5. The process for recycling waste plastics according to claim 1, characterized in that: the temperature of the extrusion in the second step is controlled at 140-190 ℃.

6. The process for recycling waste plastics according to claim 1, characterized in that: the waste plastic is one of polyethylene, polypropylene and polyvinyl chloride.

7. The process for recycling waste plastics according to claim 1, characterized in that: the dihydroxy POSS is made by the steps of:

mixing hydrogen-containing POSS and anhydrous tetrahydrofuran, adding chloroplatinic acid, dropwise adding an allyl alcohol tetrahydrofuran solution, reacting at 60-90 ℃ for 24 hours, performing rotary evaporation, and performing vacuum drying to obtain the dihydroxy POSS.

8. The process for recycling waste plastics according to claim 7, characterized in that: the hydrogen-containing POSS is made by the following process:

adding anhydrous tetrahydrofuran into octaphenyl POSS sodium salt under the protection of nitrogen, stirring uniformly, adding triethylamine, reacting for 1h in ice bath at 0 ℃, dropwise adding a tetrahydrofuran solution of methyldichlorosilane, reacting for 4h, then raising the temperature to room temperature, reacting for 16h, filtering, performing column separation after spin-drying the filtrate, and performing vacuum drying to obtain hydrogen-containing POSS.

9. The process for recycling waste plastics according to claim 1, characterized in that: the carboxyl-containing diisocyanate is prepared by the following steps:

mixing hexamethylene diisocyanate and anhydrous dichloromethane, heating to 75 ℃, dropwise adding an anhydrous dichloromethane solution of 2, 2-dimethylolpropionic acid, reacting for 2 hours, and performing rotary evaporation to obtain the carboxyl-containing diisocyanate.

Technical Field

The invention belongs to the technical field of waste plastic regeneration, and particularly relates to a waste plastic regeneration process.

Background

The plastic belongs to a high polymer material, is difficult to decompose in the nature after being discarded, and generates toxic gas to harm human health during incineration treatment. But the waste plastics belong to recyclable garbage, and the waste plastics are made into plastic particles as raw materials of the plastics, so that the waste plastics can be recycled, and the pollution of the waste plastics to the environment is reduced. However, the waste plastic reclaimed material has the defects of brittle quality, poor toughness and poor wear resistance.

For example, chinese patent CN 107746491B discloses a method for regenerating a composite flame retardant material from waste plastics, which comprises the following steps: 1) treating waste plastics; 2) mixing materials: drying the waste plastic particles, fly ash, rutile type titanium dioxide, a lubricant, a binder, a phosphorus flame retardant, a light stabilizer and dilauryl thiodipropionate according to the weight ratio of (60-80): (120-160): (20-40): (3-8): (1-6): (0.02-0.08): (0.3-0.9): (0.2-0.6) uniformly mixing and stirring in a high-speed stirrer to obtain a mixture; 3) granulating; 4) and (4) extrusion molding. The invention recycles the waste thermosetting plastic, and overcomes the defects of brittle quality, bending strength, tensile strength, elongation at break and poor flame retardant property of the plastic recycled material. In order to increase the strength of the regenerated plastic, fly ash and rutile type titanium dioxide filler are added. However, the dispersibility of the fly ash and rutile type titanium dioxide filler in a waste plastic system cannot be effectively ensured, and various properties of the obtained material are influenced.

Therefore, the invention provides a waste plastic regeneration process.

Disclosure of Invention

The invention aims to provide a waste plastic regeneration process.

The technical problems to be solved by the invention are as follows: the regenerated material of the waste plastics has the technical problems of brittleness, poor toughness and poor wear resistance.

The purpose of the invention can be realized by the following technical scheme:

a waste plastic regeneration process comprises the following steps:

firstly, crushing and sieving waste plastics, soaking in alkali liquor, cleaning and drying to obtain waste plastic particles;

secondly, adding the waste plastic particles and the auxiliary agent into a high-speed stirrer, stirring and mixing uniformly at the temperature of 110-120 ℃, and then extruding and granulating to obtain the waste plastic regenerated plastic.

Further, the sieving in the step one is a 70-mesh sieving, so that the alkali liquor is fully contacted with impurities in the subsequent soaking operation.

Further, the soaking time in the step one is 30-60min, so that impurities on the waste particles can be conveniently removed.

Further, the drying temperature in the first step is 30-50 ℃.

Further, the temperature of the extrusion in the second step is controlled at 140-190 ℃.

Further, the waste plastic is one of polyethylene, polypropylene and polyvinyl chloride.

Further, the auxiliary agent is prepared by the following steps:

s1, mixing the modified castor oil, the dihydroxy POSS and the N, N-dimethylformamide, adding p-toluenesulfonic acid, reacting for 3 hours at 75 ℃, cooling to 20 ℃, performing rotary evaporation to remove the solvent, drying in vacuum at 60 ℃ to constant weight to obtain an intermediate 1, and reacting carboxyl and hydroxyl by using the reaction, wherein the molar ratio of the modified castor oil to the dihydroxy POSS is 1: 3.2 to 3.4, wherein the adding mass of the p-toluenesulfonic acid is 0.3 to 1 percent of the mass of the modified castor oil;

the molecular structural formula of the intermediate 1 is shown as follows:

s2, mixing the intermediate 1, the carboxyl-containing diisocyanate and the anhydrous dichloromethane, heating to 80 ℃, reacting for 3 hours, adding the hydroxyl-terminated polyether modified polydimethoxysiloxane, continuing to react for 6 hours, carrying out reduced pressure rotary evaporation, and drying in vacuum at 40 ℃ to constant weight to obtain the auxiliary agent, wherein the reaction of isocyanate and hydroxyl is utilized, and the molar ratio of the intermediate 1, the carboxyl-containing diisocyanate and the hydroxyl-terminated polyether modified polydimethoxysiloxane is 1: 3.1-3.3: 3.1-3.3.

The molecular structural formula of the assistant is as follows:

is-

Further, the modified castor oil is prepared by the following steps:

mixing castor oil, tetrahydrofuran and succinic anhydride, adding p-toluenesulfonic acid, performing reflux reaction for 12 hours at 85 ℃ under stirring, performing reduced pressure rotary evaporation, and performing vacuum drying at 45 ℃ to obtain modified castor oil, wherein the molar ratio of castor oil to succinic anhydride is 1: 3.4-3.6, wherein the adding mass of the p-toluenesulfonic acid is 0.5-1.2% of the adding mass of the castor oil.

The reaction formula is shown as follows:

further, the dihydroxy POSS is made by the steps of:

adding isopropanol into a flask provided with a condensation pipe and magnetic stirring, sequentially adding phenyltrimethoxysilane, deionized water and flaky sodium hydroxide under stirring, uniformly stirring, heating a reaction system to 72 ℃ by using an oil bath pot, carrying out reflux reaction for 6 hours under the nitrogen atmosphere, stirring and reacting for 18 hours at normal temperature, removing the isopropanol from the obtained mixed solution through rotary evaporation, and carrying out vacuum drying for 12 hours at 65 ℃ to obtain octaphenylPOSS sodium salt, wherein the dosage ratio of the isopropanol, the phenyltrimethoxysilane, the deionized water and the flaky sodium hydroxide is 120-200 mL: 0.13-0.14 mol: 2-4 mg: 0.1 mol; adding octaphenyl POSS sodium salt into a three-neck flask, adding anhydrous tetrahydrofuran under the protection of nitrogen, stirring uniformly, adding triethylamine, reacting for 1h in ice bath at 0 ℃, slowly dropwise adding a tetrahydrofuran solution of methyl dichlorosilane by using a constant-pressure funnel at a dropwise speed of 2-4 drops/second for 4h, then raising the temperature to room temperature for 16h, filtering after the reaction is finished, performing column separation after the filtrate is dried in a spinning mode (the volume ratio of dichloromethane to petroleum ether is 1: 2), and performing vacuum drying to constant weight to obtain hydrogen-containing POSS, wherein the molar ratio of octaphenyl POSS to triethylamine to dimethylchlorosilane is 1: 2-2.5: 2.3-3; mixing hydrogen-containing POSS and anhydrous tetrahydrofuran, adding chloroplatinic acid, slowly dropwise adding an allylic alcohol tetrahydrofuran solution by using a constant pressure funnel, wherein the dropwise adding speed is 1 drop/second, the reaction is carried out at 60-90 ℃ for 24 hours, the constant weight of rotary evaporation and vacuum drying is obtained, dihydroxy POSS is obtained, and the hydrosilylation reaction of olefin is utilized, wherein the molar ratio of the hydrogen-containing POSS to the allylic alcohol is 1.1-1.3: 4, the mass of the chloroplatinic acid is 8-15% of that of the allyl alcohol.

The reaction formula is shown as follows:

further, the carboxyl group-containing diisocyanate is prepared by the following steps:

mixing hexamethylene diisocyanate and anhydrous dichloromethane, heating to 75 ℃, dropwise adding an anhydrous dichloromethane solution of 2, 2-dimethylolpropionic acid by using a constant-pressure funnel at a dropping speed of 1 drop/second, stirring for reacting for 2 hours, removing a solvent by rotary evaporation to obtain carboxyl-containing diisocyanate, and utilizing the reaction of hydroxyl and isocyanate, wherein the molar ratio of the 2, 2-dimethylolpropionic acid to the hexamethylene diisocyanate is 1: 2.1-2.3.

The reaction formula is shown as follows:

the invention has the beneficial effects that:

the invention adds the auxiliary agent in the process of the waste plastic regeneration process, thereby solving the technical problems of brittle quality, poor toughness and poor wear resistance of the waste plastic regeneration material.

The assistant has excellent compatibility with waste plastics, which is shown in the following steps: compared with inorganic filler, the auxiliary agent has better compatibility with the waste plastic because the auxiliary agent and the waste plastic particles are both high polymer materials, and the auxiliary agent has better compatibility with the waste plastic because the auxiliary agent contains a large number of silica chains which have excellent flexibility and mobility (determined by the low surface energy property of the silica chains) and can migrate in the composite high polymer material compared with common high polymer materials, so that the excellent compatibility between the auxiliary agent and the waste plastic is created, and a good foundation is laid for modifying the performance of the waste plastic by the auxiliary agent;

the auxiliary agent is obtained by gradually reacting modified castor oil, dihydroxy POSS, carboxyl-containing diisocyanate and hydroxyl-terminated polyether modified polydimethoxysiloxane, so that the molecule of the auxiliary agent contains a POSS structure, a linear siloxane chain, a polyether chain and carboxyl, the POSS structure is a closed cage-shaped structure consisting of inorganic Si-O-Si chain links, and the molecule mainly contains Si-O bonds and has high bond energy, so that the auxiliary agent belongs to a typical nano-sized material, and the introduction of the auxiliary agent improves the strength, wear resistance, heat resistance and flame retardance of waste plastic particles; secondly, the linear siloxane chain and the polyether chain are used as flexible chains, and the introduction of the flexible chains can greatly improve the toughness of the waste plastic particles and improve the defect of brittleness of the waste plastic particles; finally, the auxiliary agent takes castor oil as a core, belongs to natural vegetable oil and has good degradability.

In conclusion, the waste plastic particles obtained by the waste plastic regeneration process provided by the invention have good toughness, strength and wear resistance.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

the modified castor oil is prepared by the following steps:

mixing 0.1mol of castor oil, 100mL of tetrahydrofuran and 0.34mol of succinic anhydride, adding 0.5 mass percent of p-toluenesulfonic acid into the castor oil, carrying out reflux reaction for 12h at 85 ℃ under stirring, carrying out reduced pressure rotary evaporation, and carrying out vacuum drying at 45 ℃ to obtain the modified castor oil.

Example 2:

the modified castor oil is prepared by the following steps:

mixing 0.1mol of castor oil, 100mL of tetrahydrofuran and 36mol of succinic anhydride, adding 1.2 mass percent of p-toluenesulfonic acid into the castor oil, carrying out reflux reaction for 12 hours at 85 ℃ under stirring, carrying out reduced pressure rotary evaporation, and carrying out vacuum drying at 45 ℃ to obtain the modified castor oil.

Example 3:

the dihydroxy POSS is made by the steps of:

adding 120mL of isopropanol into a flask provided with a condenser pipe and magnetic stirring, sequentially adding 0.14mol of phenyltrimethoxysilane, 4mg of deionized water and 0.1mol of flaky sodium hydroxide while stirring, heating a reaction system to 72 ℃ by using an oil bath pot after uniformly stirring, carrying out reflux reaction for 6 hours under the nitrogen atmosphere, carrying out stirring reaction for 18 hours at normal temperature, removing the isopropanol from the obtained mixed solution through rotary evaporation, and carrying out vacuum drying for 12 hours at 65 ℃ to obtain octaphenyl POSS sodium salt; adding 0.1mol of octaphenyl POSS sodium salt into a three-neck flask, adding 150mL of anhydrous tetrahydrofuran under the protection of nitrogen, stirring uniformly, adding 0.2mol of triethylamine, reacting for 1h at 0 ℃ in an ice bath, slowly dropwise adding 0.23mol of a tetrahydrofuran solution of methyl dichlorosilane by using a constant-pressure funnel at a dropwise adding speed of 2 drops/second, reacting for 4h, raising the temperature to room temperature, reacting for 16h, filtering after the reaction is finished, spin-drying the filtrate, performing column separation (the volume ratio of dichloromethane to petroleum ether is 1: 2), and performing vacuum drying to constant weight to obtain hydrogen-containing POSS; mixing 0.11mol of hydrogen-containing POSS and 150mL of anhydrous tetrahydrofuran, adding 8% chloroplatinic acid of the mass of the propenol, slowly dropwise adding 4mol of tetrahydrofuran solution of the propenol by using a constant-pressure funnel at the dropping speed of 1 drop/second, reacting for 24 hours at 60 ℃, performing rotary evaporation, and performing vacuum drying to obtain the constant weight of the dihydroxy POSS.

Example 4:

the dihydroxy POSS is made by the steps of:

adding 200mL of isopropanol into a flask with a condenser pipe and magnetic stirring, sequentially adding 0.14mol of phenyltrimethoxysilane, 4mg of deionized water and 0.1mol of flaky sodium hydroxide while stirring, heating a reaction system to 72 ℃ by using an oil bath pot after uniformly stirring, carrying out reflux reaction for 6 hours under the nitrogen atmosphere, carrying out stirring reaction for 18 hours at normal temperature, removing the isopropanol from the obtained mixed solution through rotary evaporation, and carrying out vacuum drying for 12 hours at 65 ℃ to obtain octaphenyl POSS sodium salt; adding 0.1mol of octaphenyl POSS sodium salt into a three-neck flask, adding 150mL of anhydrous tetrahydrofuran under the protection of nitrogen, stirring uniformly, adding 0.25mol of triethylamine, reacting for 1h at 0 ℃ in an ice bath, slowly dropwise adding 0.3mol of a tetrahydrofuran solution of methyl dichlorosilane by using a constant-pressure funnel at a dropwise adding speed of 2 drops/second, reacting for 4h, then raising the temperature to room temperature, reacting for 16h, filtering after the reaction is finished, spin-drying the filtrate, performing column separation (the volume ratio of dichloromethane to petroleum ether is 1: 2), and performing vacuum drying to constant weight to obtain hydrogen-containing POSS; mixing 0.13mol of hydrogen-containing POSS and 150mL of anhydrous tetrahydrofuran, adding chloroplatinic acid accounting for 15% of the mass of the allyl alcohol, slowly dropwise adding a tetrahydrofuran solution of 4mol of the allyl alcohol by using a constant-pressure funnel at the dropping speed of 1 drop/second, reacting at 90 ℃ for 24 hours, performing rotary evaporation, and performing vacuum drying to obtain the constant weight dihydroxyPOSS.

Example 5:

the carboxyl-containing diisocyanate is prepared by the following steps:

mixing 0.21mol of hexamethylene diisocyanate and 100mL of anhydrous dichloromethane, heating to 75 ℃, dropwise adding 50mL of anhydrous dichloromethane solution containing 0.1mol of 2, 2-bis (hydroxymethyl) propionic acid by using a constant-pressure funnel at a dropping speed of 1 drop/second, stirring for reaction for 2h, and removing the solvent by rotary evaporation to obtain the carboxyl-containing diisocyanate.

Example 6:

the carboxyl-containing diisocyanate is prepared by the following steps:

mixing 0.23mol of hexamethylene diisocyanate and 100mL of anhydrous dichloromethane, heating to 75 ℃, dropwise adding 50mL of anhydrous dichloromethane solution containing 0.1mol of 2, 2-bis (hydroxymethyl) propionic acid by using a constant-pressure funnel at the dropping speed of 1 drop/second, stirring for reaction for 2h, and removing the solvent by rotary evaporation to obtain the carboxyl-containing diisocyanate.

Example 7:

the auxiliary agent is prepared by the following steps:

s1, mixing 0.1mol of the modified castor oil prepared in the embodiment 1, 0.32mol of the dihydroxy POSS prepared in the embodiment 3 and 150mLN, N-dimethylformamide, adding p-toluenesulfonic acid accounting for 0.3-1% of the mass of the modified castor oil, reacting at 75 ℃ for 3h, cooling to 20 ℃, performing rotary evaporation to remove the solvent, and performing vacuum drying at 60 ℃ to constant weight to obtain an intermediate 1;

s2, mixing 0.1mol of intermediate 1, 0.31mol of carboxyl-containing diisocyanate prepared in example 5 and 100mL of anhydrous dichloromethane, heating to 80 ℃, reacting for 3h, adding 0.31mol of hydroxyl-terminated polyether modified polydimethoxysiloxane, continuing to react for 6h, decompressing and rotary steaming, and drying in vacuum at 40 ℃ to constant weight to obtain the assistant.

Example 8:

the auxiliary agent is prepared by the following steps:

s1, mixing 0.1mol of the modified castor oil prepared in the embodiment 2, 0.34mol of the dihydroxy POSS prepared in the embodiment 4 and 150mLN, N-dimethylformamide, adding p-toluenesulfonic acid accounting for 0.3-1% of the mass of the modified castor oil, reacting at 75 ℃ for 3h, cooling to 20 ℃, performing rotary evaporation to remove the solvent, and performing vacuum drying at 60 ℃ to constant weight to obtain an intermediate 1;

s2, mixing 0.1mol of intermediate 1, 0.33mol of carboxyl-containing diisocyanate prepared in example 6 and 100mL of anhydrous dichloromethane, heating to 80 ℃, reacting for 3h, adding 0.33mol of hydroxyl-terminated polyether modified polydimethoxysiloxane, continuing to react for 6h, decompressing and rotary steaming, and drying in vacuum at 40 ℃ to constant weight to obtain the assistant.

Example 9:

a waste plastic regeneration process comprises the following steps:

firstly, crushing and sieving polyethylene waste plastics by a 70-mesh sieve, soaking in alkali liquor for 30min, cleaning, and drying at 30 ℃ to obtain waste plastic particles;

secondly, adding the waste plastic particles and the auxiliary agent prepared in the embodiment 7 into a high-speed stirrer, stirring and mixing uniformly at 110 ℃, and then extruding and granulating to obtain the waste plastic regenerated plastic, wherein the extrusion temperature is controlled at 140 ℃.

Example 10:

a waste plastic regeneration process comprises the following steps:

firstly, crushing and sieving polypropylene waste plastics by a 70-mesh sieve, soaking in alkali liquor for 40min, cleaning, and drying at 40 ℃ to obtain waste plastic particles;

secondly, adding the waste plastic particles and the auxiliary agent prepared in the embodiment 7 into a high-speed stirrer, stirring and mixing uniformly at 115 ℃, and then extruding and granulating to obtain the waste plastic regenerated plastic, wherein the extrusion temperature is controlled at 150 ℃.

Example 11:

a waste plastic regeneration process comprises the following steps:

firstly, crushing and sieving polyvinyl chloride waste plastics by a sieve of 70 meshes, soaking in alkali liquor for 60min, cleaning, and drying at 50 ℃ to obtain waste plastic particles;

secondly, adding the waste plastic particles and the auxiliary agent prepared in the embodiment 7 into a high-speed stirrer, stirring and mixing uniformly at 120 ℃, and then extruding and granulating to obtain the waste plastic regenerated plastic, wherein the extrusion temperature is controlled at 190 ℃.

Comparative example 1:

compared with the example 9, the waste plastic regeneration process is different in that no auxiliary agent is added, and the rest is the same.

Comparative example 2:

compared with the example 10, the waste plastic regeneration process is different in that no auxiliary agent is added, and the rest is the same.

Comparative example 3:

compared with the example 11, the difference of the waste plastic regeneration process is that no auxiliary agent is added, and the rest is the same.

Example 12:

the waste plastic particles obtained in examples 9 to 11 and comparative examples 1 to 3 were subjected to the following performance tests:

impact strength of the simply supported beam notch: testing the impact performance of the GB/T1043 plastic simply supported beam;

tensile property: testing according to GB/T528;

wear resistance: testing according to GB/T1698;

heat distortion temperature: testing according to the measurement of GB/T1634 plastic load deformation temperature;

the test results are shown below:

from the above data, it can be seen that the strength, wear resistance and thermal stability of the waste plastics obtained in examples 9 to 11 are superior to those of the corresponding properties of the waste plastics obtained in comparative examples 1 to 3.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The foregoing is illustrative and explanatory only and is not intended to be exhaustive or to limit the invention to the precise embodiments described, and various modifications, additions, and substitutions may be made by those skilled in the art without departing from the scope of the invention or exceeding the scope of the claims.