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GB/T19277.1-2025 is about to be implemented, testing, application and analysis of fully biodegradable plastic shopping bags
Date: 2025-11-04Read: 74
In recent years, with the development of new formats such as e-commerce, express delivery, and food delivery, the consumption of plastic shopping bags has shown a rapid upward trend, resulting in increasingly severe pollution to the environment. selfNational standard for biodegradable plastic shopping bags (GB/T 38082-2019)Since its implementation more than five years ago, in line with the national "plastic limit order" policy, China has reduced about 20 billion traditional plastic bags annually, equivalent to saving 1.2 million tons of oil resources and reducing 840000 tons of carbon dioxide emissions.
Biodegradable plastics refer to the degradation of natural microorganisms under conditions such as soil and/or sandy soil, and/or specific conditions such as composting, anaerobic digestion, or aqueous media, which ultimately degrade into carbon dioxide (CO)2）Or/and methane (CH)4）Water (H)2O) A plastic containing mineralized inorganic salts of its elements and new biomass. The degradation mechanism of biodegradable plastics is shown in Figure 1. Promoting the use of biodegradable plastics instead of disposable non biodegradable plastics can to some extent solve the problem of plastic pollution.
Figure 1 Degradation mechanism of biodegradable plastics
At present, the main components of biodegradable plastic products in the market are polybutylene terephthalate (PBAT), polylactic acid (PLA), starch (ST), as well as inorganic fillers (TALC) or calcium carbonate (CaCO)3）Made. Under the promotion of the Chinese government, significant progress has been made in biodegradable plastic technology in China. The technological level of biodegradable materials such as PLA, PBAT, and PHA continues to improve, and production costs gradually decrease, providing technical support for the widespread application of biodegradable plastic shopping bags.
Table 1 Technical Comparison between Two Versions of GB/T19277.1
Both revisions are equivalent to using ISO14855-1, mainly because the second edition of ISO 14855-1 replaces the first edition (ISO 14855-1:2005). The second edition has made minor revisions to the first edition, mainly aimed at clarifying the wording of the fourth paragraph of clause 8.1.
This article is based on the principle of composting testing to test and analyze the biodegradation rate and compliance of fully biodegradable plastic shopping bags (material: PBAT+PLA+ST).
Total dry solids test: The proportion of the mass of the sample after cooling and constant weight under 105 ℃ air drying conditions to the original sample Volatile solids (organic components) testing: The percentage of mass loss to the total dry solids content after burning the sample at a high temperature of 550 ℃ Total Organic Carbon Content (TOC) Test: Dry basis results were obtained using TOC-L CPH+Solid Sample Module SSM-5000A Total Organic Carbon Analyzer
Conduct tests on the total dry solids, volatile solids, total organic carbon, and pH of the docking material, reference material, and test material, respectively. Before using compost soil, remove large inert substances and screen with a 0.5 cm sieve. Cut the test material (plastic bag) into pieces with a maximum surface area of no more than 2cm * 2cm. The processed sample is shown in Figure 2.
Figure 2: Pre treated reference materials, experimental materials, and inoculum
According to the requirements of GB/T19277.1-2025 and GB/T 38082-2019 standards, the sample pretreatment and indicators are shown in Table 2, and the sample test results are shown in Table 3.
Table 2 Appearance and Indicators of Samples
Table 3 Sample Test Results
2.2.2 Controlled Industrial Composting Test
Based on the standard GB/T19277.1-2025, biodegradation performance testing was conducted under aerobic industrial composting conditions. The experimental temperature is 58 ℃± 2 ℃, and the moisture content of the inoculum is controlled at 50%~55%. The sample material (or reference material) and inoculum are thoroughly stirred and mixed in a dry weight ratio of 1:6, and loaded into the reaction vessel. The experimental process requires sufficient aeration, with an oxygen concentration of not less than 6%, and regular mixing. Blank test, reference test, and sample test each require testing 3 parallel samples and taking the average. During the routine 45 day to 6 month experimental period, a continuous infrared carbon dioxide sensor is used to quantitatively test the carbon dioxide content emitted from each composting container. The ratio of the cumulative carbon dioxide release after deducting the blank to the theoretical carbon dioxide release is the biological decomposition rate.
The test material for this test reached a relatively stable state in the biodegradation rate curve after 128 days of testing, and the test was terminated. According to the requirements of GB/T38082-2019, the relative biodegradation rate of the mixture should be ≥ 90%. The relative biodegradation rate is the ratio of the sample biodegradation rate to the reference biodegradation rate. The biodegradation rate of the reference material in this experiment is89.34%The biodegradation rate of the experimental material is81.27%The relative biodegradation rate is90.97%Meet the requirements of the standard biodegradation rate index. The carbon dioxide emissions of the test materials and reference materials during the experimental period are shown in Figure 3, and the biodegradation rate is shown in Figure 4.
Figure 3: Carbon dioxide emissions from experimental and reference materials
Figure 4: Biodegradation rates of experimental and reference materials
In the composting experimentearlyThree key indicators require special attention:
(1) After 45 days, the decomposition rate of the reference material exceeded 70%;
(2) During the experiment, the relative deviation of the biodegradation rate of each compost container shall not exceed 20%;
(3) Within 10 days of cultivation, the average amount of CO produced by the inoculum per gram of volatile solids in a blank container250mg~150mg。 Only when the experiment meets the indicators can it be recognized as valid.
The experimental period is relatively long, with a temperature maintained at 58 ℃. The inoculum is prone to dehydration and agglomeration, requiring regular replenishment of distilled water and regular stirring to ensure that the inoculum and material mixture are in a moist state with a moisture content of about 50%, which is beneficial for the effective activity of microorganisms.
Although there are currently many rapid detection technologies available in the degradation detection market, utilizing material characterization techniques such as FTIR, DSC, etc. for rapid component analysis. However, a single characterization method cannot accurately identify the composition of mixed materials/products, nor can it determine whether the biodegradation rate meets the standard. Testing using composting methodSingle material or mixed materialBiodegradable products are still one of the current methods.
The quantitative methods of composting include titration, weight method, gas chromatography, continuous infrared analyzer, etc. In order to solve the problems of long testing time, high cost, and manual monitoring, it is recommended to use intelligent equipment with continuous infrared carbon dioxide sensors for quantitative testing to complete the degradation performance testing of biodegradable materials/products. It can achieve intelligent monitoring of the entire process, automatic temperature control, regular mixing, sufficient aeration, and automatic judgment of data validity. During the experiment, the daily carbon dioxide generation and degradation rate data of each composting container, as well as the released carbon dioxide curve and biodegradation rate curve, can be directly exported for final reporting. Helps to improve the quality and efficiency of compostable degradation testing projects.