How was the composition of plastics and paper products changed in the last 30 years? State possible reasons for such changes.

To understand how the composition of plastics and paper products has changed over the last 30 years, we can look into scientific advancements, environmental concerns, and market demands. Here's an explanation of the changes and possible reasons for each:

1. Plastics:
Plastics have experienced several composition changes due to the following reasons:

a) Shift towards biodegradability: Environmental concerns have driven the demand for biodegradable plastics, meaning plastics that can break down naturally and minimize their environmental impact. This has led to the development of new plastic compositions, such as biopolymers derived from renewable sources like cornstarch, sugarcane, or algae.

b) Reduction of hazardous additives: Over the years, there has been a push to reduce the use of hazardous additives in plastics, such as phthalates and bisphenol A (BPA). These additives were commonly used to enhance flexibility or durability but have been found to pose health and environmental risks. Substitutes and alternative compositions have been developed to replace these additives.

c) Improved strength and performance: Advancements in polymer science and engineering have allowed for the development of plastics with improved strength, durability, and performance characteristics. This includes the incorporation of reinforcing fibers, nano-fillers, or combinations of different polymer types to enhance specific properties like heat resistance or impact strength.

2. Paper products:
The composition of paper products has also undergone changes due to various factors:

a) Recycled content: With increasing concerns about deforestation and sustainability, there has been a greater emphasis on using recycled materials in paper production. Over the last 30 years, the percentage of recycled content in paper products has generally increased, reducing the reliance on fresh wood fibers.

b) Fiber sourcing: In recent years, there has been a growing demand for papers made from alternative fiber sources, such as agricultural residues (e.g., wheat straw) or non-wood fibers (e.g., bamboo, hemp). These alternatives offer advantages like rapid regrowth and lower environmental impact, prompting manufacturers to incorporate them into paper compositions.

c) Chemical processes: Advances in chemical processes have allowed for more efficient and eco-friendly paper production. For instance, the use of chlorine-based bleaching agents has been reduced or eliminated, leading to less toxic byproducts and a decrease in environmental impact.

It's important to note that the changes in plastic and paper compositions are ongoing, driven by continuously evolving scientific research, environmental concerns, and consumer preferences.