For a long time, around the waste caused by plastic "white pollution", there are a lot of controversy in society. Whether it is landfill or other methods, waste plastic products persist in the environment very long time, will be left behind four decades, blocked sewers and drains, scattered in the river, beach, trees, ocean, pose a threat to wildlife . To this end, it was proposed to ban plastic packaging, it was suggested that tax.

Good environment to manage. Needless to say, we should minimize the use, reusable bag reuse and recycling used plastic products. This strategy there are still many limitations, some can not be recycled, it is difficult recovery, recycling of plastic products cost much, we need to increase efforts to find better and more practical approach. Currently, the worldwide research and development focused on the use of degradable plastic hot the plastic products manufacturing. Therefore, we are faced with resource and plastic, plastic and the environment, the balance between costs and benefits, etc., can follow the "little less, recycling point, the degradation that" the principle of strategy.

Degradable plastics research and development a long time. Early for the polyolefin (PO) photodegradation of plastics, light - biodegradable, inorganic fill a large number of medium-term environment can be modified consumptive materials have made some progress and market research applications. The problem is that such products are not biodegradable polyolefin effectively control life, the ultimate degradation products can not ensure complete conversion to CO2, water and humus (biomass). As in recent years, biodegradable polyester materials (plastics can be hydrolyzed) the advent and application of degradable polyolefin plastics research seems to be an end.

Degradation of Polyethylene film technology to face the confusion

Degradation of Polyethylene film of China in twenty years, has experienced a degradation of light, light - biodegradable technology stage. The main technical measures are added photosensitizers or photosensitizer filled with starch modified sharing. After years of testing, the conclusion mixed, the result is basically negative. Focus on film life is controllable, can completely degrade. China is a vast, climate and soil conditions vary widely, nonwoven bag farming methods are very different. Successfully tested in the Northeast region controlled the life of the product, to use the results of different Northwest, Southwest is changing to a different conclusion. If life is shorter than the design life, moisture damaged, leading to crop failures, or even never produced; if life longer than the design life, or spend a lot of labor costs and Collection of plastic film, plastic film or so left in the land. Remain on the land of the plastic film if the light, heat, oxygen, water, microbes, bacteria and other factors, completely degraded, and finally into CO2, water and biomass (humus), does not affect the subsequent planting, is completely to accept. But now the result is that no matter what kind of degradation of technologies based on polyethylene film was buried on land or thrown in the fields, are not completely degraded, remain a long period (last ten years), seriously affecting the subsequent planting, but also cause visual pollution. As a result, the original film back to the starting point, re-use of ordinary polyethylene blown film.
Do they go to the other. Since the degradation of technology is not reliable, imperfect, industry scholars, it should be easy to use anti-aging recycling technology to reduce pollution and increase recycling rates of oil resources. Granulator recycling plastic film made of other renewable plastics can also be burned as supplemental fuel for heat. United States and Europe for a long period of time using the technology, the effect is good. New problem has emerged: anti-aging and easy recovery of film thickness increases, rising raw material costs, labor costs even more than recycling the scrap value of the membrane. Technology to promote frustration, especially in China, high input and low output, a huge social event almost no interest. Cycle, agricultural mulch film back is neither weather, nor the general degradation of polyethylene blown film.

Biodegradable plastic film technology is to be recognized and welcomed the growing industry, the crux of the problem is technical perfection. China has become the world's unique agricultural plastic use power. The average annual consumption of agricultural film to 45 million tons, covering an area of
​​more than 2 million mu. Agricultural sector had a statistical study of plastic debris in the residual land is less than 7 kg / acre, not affect the subsequent planting. But today the situation is, the land of plastic debris in the residue is much higher than this limit. According to the author two months ago in China, the largest amount of agricultural plastic film used to cover the largest area of ​​the Xinjiang regional survey showed that: the ground covered by plastic film to promote the most extensive and in-depth Xinjiang Production and Construction Corps, for example, the various groups in their jurisdiction cotton, tomato cultivation, the land remains in the film accumulated up to 35 kg / mu seriously affected crops and growth. Residual plastic debris in the soil and put up a barrier between the seeds, blocking the water, fertilizer and other nutrients, leading to seed does not germinate, recycle PET reusable bag no emergence. Author of many workers had to replant, spend a lot of manpower, material resources, also affect production. Corps to take a lot of incentives or coercive measures to create a dedicated machine, requiring recycling of plastic film, but with little success. Therefore, China needs to control the entire life of degradation of plastic film.

Advances in technology for the solution to the problem provides a new way. Since the degradation of polyethylene film or the use of anti-aging technology in this or that problem, why do not we use non-biodegradable polyethylene transparent cover material? In recent years, recycling bag polylactic acid (ester) PLA, aliphatic polyester (PBS) and other biodegradable resins have been brought forth. The type of resin used for agricultural mulch film are growing. However, there are several practical problems can not be avoided. Chinese farmers need is a low investment, low one-time investment of production. China has the world's thinnest polyethylene film to do (0.003mm), the average life of 60-90 days. The cost of polyester or modified polyester or prices can compete with polyethylene or competition? The ultra-thin polyester molding technology is not yet pass. More of a problem can not be ignored, farming is a high-water, high temperature, high humidity environment, multi-microbial environment, multi-chemical environment, is a composting environment, the main mechanism of the hydrolysis of polyester products can meet the growing life term needs, life control can be achieved?

With biodegradable polyester material, the degradation of polyethylene film on the abolition of the industry's increasing calls, even thought it was a final ruling of the death penalty has been technology. Indeed, polyethylene is not biodegradable (ie can not be completely degraded), but its oxidation products can not biodegradable? The environment can eventually consumptive? Can not but affect the soil structure and fertility (nutrients)?

Oxidation - biodegradable plastic additives opportunities

Oxidation developed by EPI Canada - bio-degradable plastic additive technology used in traditional polyolefin plastic products, plastic does not change or affect the traditional manufacturing process; products can use in the production life of the "programming" manufacturing; rpet bag products with the traditional strength and other characteristics Plastic same; products can also be recycled and recycling use; products either compost, landfill, or discard, and ultimately can become CO2, water and biomass. Also, oxidation - biodegradable plastic additives meet the U.S. FDA and EU for food applications EFSA.

More than three years, EmoChiellini research team led by Professor University of Pisa has been added to the polyolefin EPI's TDPA comprehensive investigation. Investigation involves the study of oxidative degradation of the sample, followed by the oxidation of solid material in the media (soil and compost) in the biodegradation. Today's work focuses on TDPA-PE samples.

TDPA-PE shopping bags with LDPE and LLDPE samples, based on the temperature up to 70
in the air, with a high tendency to oxidation (by measuring the absorption of oxygen). Oxidation process in the molecular weight polyethylene significant, progressive reduction (carbon chain is broken into smaller molecules). Degradation rate depends on temperature and relative humidity. Temperature, relative humidity decreases, the speed continues to increase. Oxidation of the polymer molecules break down into fragments due to the oxidation process. Film inevitably weakened, broken down into smaller and smaller fragments. These hydrophilic fragments, exposed or buried in the soil, recycle PET bag or mixed with mature compost, at a set time, biodegradable as 65% -75% of the mineralized material (by micro-organisms to convert carbon dioxide) and 10% - 15% of the cell biomass. In all cases, the evidence in the ordinary PE sample was inert under the conditions, TDPA-PE samples to oxo-biodegradable.

Based on EPI's Totally Degradable Plastic Additives (TDPA?) Technology, we try and apply it to the polyolefin agricultural film, accelerated aging laboratory and field evaluation of a combination of experimental impact assessment, carried out their preliminary study.

New technology in the pilot study of film

Oxidation - technology does not change the general biodegradable plastics processing, equipment, performance, life can use the flux region, recycle bag the use of seasonal maximum temperature, minimum temperature, average temperature, and humidity, rainfall, altitude, target life to tailor-made additives (programming). Moreover, processing and storage time does not affect the manufacturing performance and life; oxidation - biodegradable plastics can also be recycled, re-use. In view of oxidation - the technical characteristics of biodegradable, we chose the southwestern province of a trial, the oxidation - biodegradable mulch film applications studied.

Test to climatic conditions

Test is located east longitude 97 ° 31 'to 106 ° 11', latitude 21 ° 8 'to 29 ° 15', with an average altitude of 2000 meters, the annual temperature is small, large diurnal temperature range, the warmest month average temperature of 19-22
, the coldest average temperature of 6-8 , light intensity 125kcL/cm2 / year, maximum temperature 35 .

Test the technical parameters of film

With a melt index of polyethylene blown film of 2.0 g / main 10 points of LLDPE, the thickness of 0.005mm, tensile load (vertical / horizontal)
1.0N, elongation at break (vertical / horizontal)% 120, right angle tear crack load (vertical / horizontal) 0.4N; Appearance: No big fish eyes, no hole in the bubble. Design divided into two groups, a group of 35 days break, the second group 50 days break. Plastic film in place after the rupture of the earth at 30cm from the surface, there should be one year after the debris was visible.

According ASTMD3826 provides that when more than 75% of the test specimen elongation is less than 5%, the degradation to complete. Therefore, according to product elongation and elongation retention rate to measure the degree of degradation products.

Designed to break-up time of 35 days of polyethylene plastic film elongation at break and elongation retention rate results in Table 2. The film rupture in the first 40 days and 45 days buried in the land, observe the bio-degradation.

Our testing is ongoing. This paper aims to initiate, recommend not to give up the industry and technical personnel of polyethylene oxide - biodegradable technology development and utilization, do not give up agricultural polyethylene film and other difficult to recycle, recycling costly, recycling lead to secondary pollution of polyethylene oxidation products - biodegradation technology development. In the new biodegradable polyester material came at the same time, non woven bag china should not be more cost-effective technology swept the shelf polyethylene degradation or abandoned, the two can co-exist entirely.

Oxidation - the hydrolysis of biodegradable plastics and polyester-type (starch) Comparison of biodegradable plastics

Oxo-biodegradable plastics and biodegradable polyester hydrolytic (starch-based) products, compared with some of the key features:

1) in any outdoor or indoor environment degradation, even without water. Most of hydrolytic microbial biodegradable plastics require more in the environment (such as compost piles) to degrade.

2) The hydrolytic degradation of biodegradable plastics generate methane, while the oxo-biodegradable plastic does not.

3) oxo-biodegradable plastics in the manufacturing process can be life planning, degradation within the stipulated time. Hydrolytic degradation of biodegradable plastics can not be pre-set speed.

4) oxo-biodegradable plastics stronger, more versatile, cheaper.

5) when the oxo-biodegradable plastics manufacturing labor and machinery used in traditional plastics with the same, will not reduce the manufacturing jobs.

6) oxo-biodegradable plastics thinner, storage and transportation space, and produce less material.

7) oxidized at room temperature biodegradable bags can be processed in conventional equipment associated with plastic waste recycling, re-manufacturing, and hydrolytic biodegradable bags can not.

8) The hydrolysis of polyester type biodegradable material costs. Starch as the starting material, consumes much energy.