Source: Link Testing Instruments Co.,Ltd.
With increasing environmental pollution and heightened environmental awareness, the concept of green environmental protection has become ubiquitous across all industries, including the packaging industry. Biodegradable, recyclable, and pollution-free alternatives to traditional plastic films are emerging in an ever-increasing number of environmentally friendly packaging materials, with biodegradable shopping bags being a key component.
Traditional plastic shopping bags are extremely common and a major contributor to "white pollution." Therefore, the development and use of biodegradable materials that meet the performance requirements of shopping bags and are readily biodegradable is an effective approach to addressing pollution and reducing the environmental burden. Impact resistance is a key indicator for evaluating the suitability of these new green materials. This article introduces an impact resistance evaluation method and verification scheme based on dart impact testing.
Test Method and Standard Reference
The testing requirements for the "Dart Impact Test" in the product standard GB/T 21661-2008, "Plastic Shopping Bags," are based on the current standard GB/T 9639.1-2008, "Plastic Film and Sheeting—Test Method for Impact Resistance—Free-Falling Dart Method—Part 1: Ladder Method." We can test samples according to this standard.
In this test, we used biodegradable hand-held vest bags as test samples.
Test Instrument and Principle Introduction
The LTMC-A Dart Impact Tester, manufactured by Link Testing Instrument Co.,Ltd., was used to test the samples. This instrument complies with GB/T 9639.1 (Test Method for Impact Resistance of Plastic Film and Sheeting—Free-Falling Dart Method) and ASTM D1709 (Standard Test Method for Impact Resistance of Plastic Film by Free-Falling Dart Method). It is suitable for measuring the impact mass and energy required to break 50% of plastic film or sheeting specimens when subjected to a free-falling dart impact from a given height.
The general principle of the free-fall dart method is to select an appropriate initial dart mass and counterweight Δm at the beginning of the test, based on the sample thickness and material. During the test, the dart freely falls to impact the sample. If the sample breaks, the weight is reduced by Δm. If the sample remains intact, the weight is increased by Δm. The dart is then struck again with the changed mass, and the weight is increased or decreased based on the test results. The test is repeated in this manner. In short, the use of weights to increase or decrease the dart mass depends on whether the previous sample broke. After testing 20 specimens, the number of broken specimens, N, is calculated. If N is 10, the test is complete. If N is less than 10, additional specimens are tested until N reaches 10. If N is greater than 10, additional specimens are tested to ensure that the number of intact specimens reaches 10. The instrument then automatically calculates and displays the specimen's impact failure mass according to the standard's formula.
Test operation process
Test results and analysis
The number of undamaged samples in this test is 9, which meets the technical requirements of dart impact in GB/T 21661. Dart impact quality is an important indicator to measure the impact resistance of packaging bags. This article tests the dart impact quality of biodegradable portable vest shopping bag samples. The test process is simple, the equipment is easy to operate, and it is safe and convenient to use. The test results show that the impact resistance of the tested samples is relatively high.
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