METHOD OF PRODUCING PLANT BIOMASS-BASED BIOPLASTIC

Abstract

This invention relates to the field of producing bioplastics. Specifically, it relates to a method of producing all key ingredients of bioplastic making from pumpkins and making of bioplastic with these ingredients. More specifically, glycerin and other chemicals are extracted from pumpkin seed oil and mixed with starches that in the pumpkin flesh to make bioplastic. The bioplastic produced with the method as disclosed in this invention possess superior properties in tensile strength and biodegradability compared to bioplastic.

Claims

1. A method of making pumpkins based bioplastic, the method comprising: Separating pumpkins into flesh and seeds, and extracting organic glycerin to react with pumpkin flesh, and producing bioplastic.

2. The method of claim 1, wherein processing pumpkin seed by extracting organic glycerin by a transesterification reaction using pumpkin seed oil with methanol.

3. The method of claim 2, wherein a catalyst is added into methanol.

4. The method of claim 2, wherein a catalyst is sodium hydroxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 is a schematic representation showing a method of the producing bioplastic with two key components derived both from pumpkins.

[0014] FIG. 2 shows tensile strength comparison result between bioplastics made with pumpkins seed derived glycerin and petroleum derived glycerin.

[0015] FIG. 3 shows biodegradability comparison result between bioplastics made with pumpkins seed derived glycerin and petroleum derived glycerin.

[0016] FIG. 4 summaries the comparison of four catalysts used in bioplastic production.

DETAILED DESCRIPTION

[0017] The following disclosure covers the method of producing bioplastic from pumpkins. Specific details of the process are provided in examples for understanding of preferred embodiment.

[0018] Mechanical Separation of Pumpkins into Flesh and Seeds

[0019] To begin with, pumpkin seeds are separated from pumpkin flesh. The pumpkin flesh is ground until it is a near-homogenous mixture with minimal surface disruptions. An optional step may be applied to remove pumpkin rind from the flesh before grounding. Pumpkin seeds are separately cleaned and dried. The de-shelled seeds are subject to a mechanic extraction apparatus such as an oil extractor for seed oil. The pumpkin seeds are crushed inside the machine, and the seed oil is flowing out through the outlet the machine. The oil is collected after filtration.

[0020] The Transesterification Procedure of Making Organic Glycerin

[0021] Pumpkin seed oil will be heated to a range between 20 C. and 70 C., such as a temperature about 45 C.-55 C. Appropriate amount of methanol, between one fifth and two fifths of the pumpkin seed oil, by volume, will be measured and dispensed into a glass container. Appropriate catalyst may be added to methanol. In one embodiment, sodium hydroxide, between 1/100 to 1/200 (weight/volume) of methanol, will be added to methanol with gentle shaking until the catalyst completely dissolved in the methanol. The methanol/catalyst mixture will then be added to pumpkin seed oil and kept in an environment between 15 C. and 35 C. for fourteen days. Two definitive phases will be formed at the end of 14 days. The top layers if consisting of biodiesel, and the bottom layers includes glycerin and other chemicals.

[0022] Glycerin can be separated from biodiesel by a separating funnel into a collecting container. The bumpkin seed derived glycerin will be used in bioplastic synthesis in the next step.

[0023] Bioplastic Process

[0024] Bioplastics, like all plastics, contain at least one polymer and at least one plasticizer. Polymers contain extensive repeating groups of monomers and often feature a long carbon chain. A plasticizer is an additive that increases the pliability or flexibility of the plastic. In the pumpkin-based bioplastic, pumpkin flesh is used as the main polymer because it contains high level of starch, itself a repeating units of glucose and other monosaccharides. The primary composition of starch in pumpkin flesh is amylose which is a linear molecule that connects through (1-4) bound to glucose molecules, and amylopectin, a branched molecule broken at (1-6) position. When exposed to heat, the amylose and the amylopectin in starch became more organized (linear) due to hydrogen bonding between the hydroxyl groups. This linearization contributes to the stiffness of the bioplastic. The ratio of amylose to amylopectin somewhat determines the bioplastic's flexibility; a higher ratio (more amylose) results in a more rigid bioplastic, whereas a lower ratio (more amylopectin) results in a more flexible bioplastic. Most plant starches contain 20 percent amylose and 80 percent amylopectin.

[0025] Glycerin extracted from pumpkin seed oil will be used as a plasticizer because it contained polar hydroxyl groups at 1.51 Debye which absorbed water. Acetic acid is used to strengthen the bonds between the plasticizer and the polymer. The ions that are present in acetic acid dissociate the polymer, making it readily dissolvable. Other chemicals the present in the pumpkin seed oil that co-extracted with glycerin improved the performance bioplastic end product such as tensile strength and biodegradability. Other aspects and advantage of this invention are discussed in the embodiment with reference of drawing.

Embodiment Examples

[0026] An embodiment of this invention is given with reference to description of the drawings.

[0027] 1,000 grams of dry pumpkin seeds are peeled and placed in an oil extractor to extract oil. Extracted oil will be subject to a stainless steel screen with mesh size 100 micron. 200 ml of extracted pumpkin seed oil will be heated to 50 C. 0.4 grams of sodium hydroxide will be added to 44 mL of methanol and mixed gently until it is fully dissolved. The methanol is then added to the pumpkin seed oil in 50 C. with gentle shaking. The mixing bottle was left alone at 25 C. for fourteen days until two definitive layers of glycerin and biodiesel was observed. The top layers is consisting of biodiesel, and the bottom layers includes glycerin and other chemicals.

[0028] Glycerin can be separated from biodiesel by a separating funnel into a collecting container. The bumpkin seed derived glycerin will be used in bioplastic synthesis in the next step. Typically, 30-55 ml glycerin will be recovered.

[0029] 100 grams of pumpkin flesh with rind removed are ground until it is a near-homogenous mixture with minimal surface disruptions. 65 mL of the pumpkin mixture was poured into a glass container. 10 mL of glycerin from the previous step and 10 mL of acetic acid (5% concentration) were also poured into pumpkin mixture and heated to 93 C. 120 mL of deionized water will be added while remained at 93 C. for 10 minutes. Afterwards, the contents of the will be poured into the tray to a designed thickness and left to cool at room temperature. In one example, 100 ml of mixture will be poured into a 1212 inch tray and bioplastic film is formed in the process. For every 11 hours, the bioplastic can be lightly heated to expedite the drying process.

[0030] After harvested from the tray, the bioplastic film is undergone a series of testing for its strength and biodegradability to compare with plastic made with petroleum derived glycerin.

[0031] Bioplastic Strength Test and Result

[0032] The testing apparatus was made with the plastic samples sandwiched between two strips of wood and secured with two clamps. The wood was rested on two elevated platforms. An S-hook was latched onto the opening of the resting clamp, and to a chain underneath the clamp. The chain connected the handle of the bucket and the S-hook. The containers were used to gravel pour in the suspended bucket until the bioplastic ripped. The plastic's weight was recorded and the test was repeated for the different plastics. The result suggests that bioplastic, with tensile strength of 14.5 kg, outperformed petroleum-based glycerin, and tensile strength of 14 kg.

[0033] Bioplastic Biodegradability Test

[0034] In a plastic container that functioned as a composter, layers of garden soil and other compost materials were prepared to simulate plastic natural degradation environment for plastics. There are two layers of composts; a brown layer that is comprised of carbon-rich items including dry fall leaves, sticks, and bark, and a green layer was made of the green materials that were damp and high in nitrogen. For green layers, damp summer leaves, unprocessed organic fruits, and unprocessed organic vegetables were used.

[0035] Ten small, equally spaced, -inch diameter holes were drilled on the bottom of the composter to serve as air passages. A tray was placed along the length of the box on the ground. This was where the composter was stationed. The composter was not in direct sunlight. Two 8 cm wood planks were evenly spaced and positioned on the tray. The composter rested on the wood.

[0036] The weight of the 5 cm5 cm0.2 cm bioplastic sheet was recorded. A string two times the length of the box was tied to the bioplastic. The other end of string was tied to a piece of paper with the bioplastic ID labeled on it.

[0037] The box was filled with alternating layers of brown materials (dried and carbon-rich), soil, and green materials (damp and nitrogen-rich). Near the middle of the box, in a soil section, the bioplastics were placed with the ID label outside the box. The box was filled of repeating layers until the top. The composter was placed on the 8 cm wooden planks on top of the tray.

[0038] For aeration, the composter was mixed every second day. The compost process continued for 21 days, at the end of which the bioplastics were carefully removed and let dry for two days. Excess dirt around the bioplastic was removed. The bioplastic was weighed and the weight was recorded. Using the final and initial weights of the bioplastic, the percent mass decrease was calculated using the following formula: Percent mass loss=(initial massfinal mass)/final*100.

[0039] In general, higher pumpkin and glycerin content yielded higher biodegradability. The percent mass loss of petroleum based plastic is only 10%, while, that of pumpkins based bioplastic is 18%.