Post-Laboratory Discussion - Preparation of Biodegradable Plastics PDF

PRAYER BEFORE CLASS Holy Spirit, Divine Creator, true source of light and fountain of wisdom! Pour forth your brilliance upon my dense intellect, dissipate the darkness which covers me, that of sin and of ignorance. Grant me a penetrating mind to understand, a retentive memory, method and ease of le...

PRAYER BEFORE CLASS Holy Spirit, Divine Creator, true source of light and fountain of wisdom! Pour forth your brilliance upon my dense intellect, dissipate the darkness which covers me, that of sin and of ignorance. Grant me a penetrating mind to understand, a retentive memory, method and ease of learning, the lucidity to comprehend, and abundant grace in expressing myself. Guide the beginning of my work, direct its progress and bring it to successful completion. This I ask through Jesus Christ, true God, and true man, living and reigning with You and the Father, forever and ever. Amen.  UST General Santos Post-Laboratory Discussion: Preparation of Biodegradable Plastics Chemistry for Engineers Laboratory Learning Objective at the end of the experiment, students are expected to: ❖ To make a plastic film from potato starch PLASTICS - derived from crude oil (petroleum) - rely more on scarce fossil fuels - when burned → release carbon dioxide → global warming - takes longer time to decompose What are BIOPLASTICS? BIOPLASTICS - form of plastic derived from renewable biomass sources (vegetable oil or corn starch) TYPES BIOPLASTICS 1. Starch based (widely used) - made from natural starch - USES: wrappers for goods packaging, drug capsules 1. Cellulose based - made of cellulose esters - USES: thermoplastics, packaging 1. Protein based - made from proteins (soy, wheat) - USES: body panels of automobiles 1. Some aliphatic polyesters BIODEGRADABILITY biodegradation is a process where organic materials are broken down by natural processes and micro-organisms - sunlight - water - bacteria - enzymes - wind abrasion  Biodegradation of bioplastics ○ can be done by several bacteria found in the soil Pseudomonas species Streptococcus species Staphylococcus species ○ bacteria break the polymer chain of potato starch ○ addition of glycerol increases the degradation of bioplastics ability to absorb water water: medium of most bacteria and microbes DEGRADABLE PLASTICS TYPES Biodegradable plastics ○ which contain a small percentage of non oil-based material (corn starch Photodegradable plastics ○ break down when exposed to sunlight Potato Starch - polymer made up of long chains of glucose unit units joined together - contains two carbohydrate polymers: - Amylose: long-chain - Amylopectin: highly- branched molecules - majority of starch Potato Starch Based Bioplastic PURPOSE OF HCl: - breaks down amylopectin to allow film formation Potato Starch Based Bioplastic PURPOSE OF ADDING GLYCEROL: - serves as plasticizer - amylose is brittle - by adding glycerol → increases flexibility and elasticity of the bioplastic HOW? 1. Glycerol disrupts the hydrogen bonds between starch molecules → weakens the rigid structure of the starch → more flexible 2. Glycerol is hygroscopic (able to absorb moisture) → further plasticize the bioplastic → increases flexibility End of discussion Do you have any questions? PRAYER AFTER CLASS Grant me, O Lord my God, a mind to know you, a heart to seek you, wisdom to find you, conduct pleasing to you, faithful perseverance in waiting for you, and a hope of finally embracing you, Amen.