Summer and summer came quietly, and the shoe cabinet at home began to smell of mystery again, and after a pair of investigations, it was found that the "culprit" was the plastic slippers that had just been replaced.
However, washing the slippers as soon as they stink doesn't work, even if they are good for a while, they stink again after a while. Even if you buy new slippers, even if you don't have any foot odor, plastic slippers will soon smell stinky.
If you don't understand, ask why plastic slippers can't escape the fate of stinking?
The number of sweat glands in the center of our feet is as high as 620 per cm², which is much higher than the 143-339 sweat glands in other parts of the hand [1]. These metabolites don't have a taste of their own, but they are the "happy home" of bacteria.
In a healthy state, the surface of our skin has a complex microbial community, and the "microbiome" of the feet is mainly composed of Acinetobacter, Staphylococcus, and Bacterius [2], although some of these bacteria can only survive in a strictly anaerobic environment, while some have evolved a set of methods to survive in an anaerobic environment, but in terms of odor, they are all the same - they all produce volatile organic compounds such as amines and sulfur-containing compounds.
Anaerobes prefer moist and enclosed environments, they often grow in large numbers inside slippers and emit an unpleasant sour smell similar to that of a toilet / Picture bug idea
These compounds smell like rotten fish, shrimp and rotten meat, and they're the main source of the smell of your plastic slippers. If you think about the alternating aerobic and anaerobic environment where you sweat and sweat, it's hard to think that slippers don't stink so prominently that they're two germs working together.
After wading through the rain and water, bathing in the bathroom, and wearing a summer, the moisture in the humid environment is mixed with bacteria to form an inorganic brine solution suitable for bacterial reproduction, and then after years of "anaerobic fermentation", the plastic slippers have simply become wearable Laotan sauerkraut.
The stinking "pot" of slippers has to be carried by a structure.
Look at your plastic slippers, bumpy ravines and even porous soles, which are water-permeable and lightweight in the shower, but they also provide shelter for dander and bacteria.
Non-slip slippers are quite common by the pool and at the beach / Picture Worm Creative
But! In addition to the design reasons that are visible to the naked eye, the microstructure determined by the material also hides a bigger smelly easter egg!
Common plastic slippers can be divided into three categories: EVA (ethylene-vinyl acetate copolymer), PVC (polyvinyl chloride), and TPU (thermoplastic polyurethane) according to their molecular structure [3].
The difference in material determines the difference in the microscopic molecular structure of the slippers, resulting in a very different living environment for bacteria, so that the slippers have the difference between smelly and smelly - you read that right, not the difference between fragrant and smelly, but the difference between smelly and more smelly.
So it's true that slippers stink is its ultimate fate.
"Feeling of" slippers have poor air permeability and are easy to breed bacteria / Picture insect creativity
Even if it's the same material, the difference in craftsmanship will make it stink very different. From the perspective of materials, the "-feeling" slippers that we commonly see today are essentially the same as the crystal sandals with "a pair of human feet" when we were children, but the mixing of foaming agents and the application of foaming process make the slippers light and soft on the one hand, shiny and not easy to be contaminated with dust, and on the other hand, they also bring the risk of bacteria settling down due to the open bubble holes caused by the damage of the bubble holes [4][5].
On the other hand, EVA material is soft and shock-resistant, has the characteristics of non-water absorption [6], and is wear-resistant and high-temperature resistant [6], which not only wears for a long time, but also adapts to the high-temperature environment of bathing; In addition, due to the longer molecular chains, the inside of the foam remains closed, even after the foaming process, reducing the hiding place for bacteria.
TPU is harder than EVA, has good stability, does not absorb water, and helps keep feet dry, and other auxiliary materials are added to enhance antibacterial and sweat absorption and breathability when used in shoe production, thereby reducing foot odor caused by sweating bacteria [7].
The structure of closed-cell microporous plastics (a) and open-cell microporous plastics (b) is different / [5]
However, the "pot" of the stinking slippers worn on the feet cannot be thrown all over the shoes themselves, and it depends on your stinky feet.
Therefore, do not neglect the toe and nail seams, which contain less oxygen and are more likely to harbor aerobic bacteria, when washing your feet [8]. You can also refer to the two commonly used national standards for the determination of deodorizing performance of antibacterial knitwear (FZ/T 73023-2006) or textiles (GB/T 33610-2019) to buy and wear socks with antibacterial properties.
After the operation, if your slippers are still stinky, we might as well give up the plastic slippers and find our own "gratitude" slippers again, such as linen slippers with better breathability and moisture absorption.