Structure-Properties Relationship Study Of Biodegradable Film Processing And Intelligent Characterization

China is an agricultural country,of which the industrial scale of agricultural film is large.The output of agricultural film in the country is increasing rapidly every year.By 2015,the output of agricultural film has reached 2.369 million tons.From the per-spective of the proportion of China's agricultural film products,however,high-end agri-cultural film products are in short supply,which accounts for only 10%.In China,the common material used to make agricultural film is polyethylene(PE)because it is cheap and low in manufacturing cost.,but the biggest disadvantage of PE is that it pollutes the environment.Therefore,people are trying to find a biodegradable material to replace the PE film.Polybutylene adipate terephthalate is a good substitute.Industrially,the film is generally processed by blown film.However,there are great problems in the processing of biodegradable film,such as:1)poor processing stability of the material;2)performance is not up to the requirements;3)workers need to spend too much time operating the machine.Therefore,it is necessary to regulate the processing parameters and modify the materials.In this paper,in response to solve the problems above,some work has been carried out as follows:1)In order to explore the relationship between the processing conditions,inner structure and the properties of the biodegradable film PBAT in the film blowing,the home-made film blowing machine and synchrotron radiation X-ray were combined to detect the bubble during the blowing processing.It is found that the evolution of the bubble can be divided into three stages:the generation of the precursor controlled by the flow field,the nucleation of the crystal controlled by the flow field and the temperature field and the growth process of the crystal controlled by the temperature field.The ad-dition of the chain extender changes the molecular chain length.Different chain length is inconsistent with the external field,leading to a different film orientation,which pro-vide a new idea for preparing film with different orientations.The addition of ADR provides a chemical cross-linking point that together with the physical cross-linking points formed by the PBAT crystals constitutes the basic skeleton of the bubble.The addition of the chain extender ADR changes the optical properties of the film.2)Based on the macroscopic stress-strain curve and the microscopic structural in-formation obtained by SAXS/WAXS,three regions are defined.In region I,the molec-ular chain of the amorphous region undergoes elastic deformation,namely affine defor-mation.After the yielding point(region ?),the oriented amorphous chain starts to crys-tallize into the metastable ?-crystal.In region ?,where the strain-hardening happens,the transition from a-crystal to P-crystal occurs through solid-solid transition mecha-nism.Therefore,the ?-crystal is found to be formed through two different pathways during stretching.Meanwhile,it can be observed that the change in transmittance and phase transition are almost synchronous.This is attributed to similarity of the refractive index of both the amorphous and crystalline region after stretching.The relationship between PBAT phase transition and optical properties is revealed from the microscopic scale,which could provide theoretical guidance for the preparation of agricultural film with higher transmittance.3)In order to realize the intelligentization of the blown film process,it is necessary to establish a knowledge map about the processing parameters and the material prop-erties,and use the machine learning algorithm to train the corresponding model.The preliminary work is to establish a polymer blown film intelligent detection platform.By improving the existing image recognition algorithm,the capture of the blown film bubble shape is realized,which is used to quantitatively characterize the stability of the blown film bubble.By designing an automated film cutting system and stretching system,integrating other optical inspection equipment onto the platform,the stability of the polymer blown film bubble and the automatic characterization of the mechanical properties and optical properties of the polymer film can be achieved.The establish-ment of a knowledge map provides high-throughput data and lays the foundation for intelligent blown film.