MINISTERY OF EDUCATION
AND TRAINING
VIETNAM ACADEMY OF
SCIENCE AND TECHNOLOGY
GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY
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NGUYEN TUAN NAM
STUDY ON THE MANUFACTURING AND PROPERTIES OF GAS
BARRIER MULTILAYERS FILMS AND APPLICATIONS
Scientific Field: Organic Chemistry
Classification Code: 62 44 01 14
DISSERTATION SUMMARY
HA NOI - 2020
The dissertation was completed at:
Institute of Chemistry
Vietnam Academy of Science and Technology
Scientific Supervisors:
1. Dr. Nguyen Tien Dung
The Faculty of Chemistry – Hanoi National University of Education
2. Dr. Nguyen Thanh Tung
Institute of Chemistry - Vietnam Academy of Science and Technology
1st Reviewer: ...........................................................................
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2nd Reviewer: ..........................................................................
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3rd Reviewer: ...........................................................................
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The dissertation will be defended at Graduate University of Science And
Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc
Viet, Cau Giay District, Ha Noi City.
At ….. hour….. date….. month …..2020.
The dissertation can be found in National Library of Vietnam and the library
of Graduate University of Science And Technology, Vietnam Academy of
Science and Technology.
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A. INTRODUCTION
1. Background
Packaging plays an important role in the food supply chain. They are
not only used to store, preserve and transport products but also used as a
marketing tool to bring added value to the product. Packaging protects food
from environmental influences such as oxygen, moisture, light, dust, volatile
compounds and microorganisms [1], it acts as a barrier between the
atmosphere around food and the outside environment. Oxygen and steam are
the two main reasons leading to the deterioration of food quality. Therefore,
the development of the gas barrier packaging products with low air and water
vapor permeability is a research direction that has been interested recently.
According to Smithers Pira, in 2015, the world consumed about 1.4 million
tons of gas barrier packaging films, in 2016 it was 1.86 million tons, with the
growth rate of 4.7%/year. The regions using the most gas barrier packaging
films were Asia-Pacific with 30.9%, followed by Western Europe (27.6%)
and North America (26.8%).
Among the materials used for packaging, plastic in the form of thin
films has many outstanding advantages compared to other packaging types
such as: light, durable, elastic, transparent, resistant to air and vapor. High
water, and at the same time have good heat sealing and sealing ability.
Polyethylene (PE) is the most commonly used plastic for packaging thanks to
its good moisture barrier, low cost, but poor resistance to O2, aromas and
essential oils. Like PE, PA6 has good moisture barrier but poor O2 and CO2
barrier. Therefore, the recent trend that scientists are most interested in
developing is to combine these polymers with another polymer with high gas
barrier ability in the form of polymer blends or multilayer films. The most
widely used and highly gas barrier polymer is EVOH [2]. Combining EVOH
with PE or PA6 can create a material that has both highly mechanical and
good gas, solvent, and moisture resistance, suitable for applications requiring
high gas barrier such as food packaging or dry agricultural packaging ...
Agriculture plays an important role in Vietnam's economy with great
developments. However, post-harvest losses of agricultural products are still
high, from 15-20% for foods, the main reason is that the research, application
and deployment of post-harvest technologies have not timely responded and
are full of requirements. In the country, there are also studies on the use of
gas barrier packaging to preserve dry food and agricultural products, but the
gas barrier packaging products on the market today are all imported products
with expensive prices. Stemming from the above problems, the thesis focuses
on: "Study on the manufacturing and properties of gas barrier
multilayer films and applications".
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2. Objectives of the dissertation
Researching and fabricating gas barrier multilayer films based on the
polyme blends and exploring the applicability of packaging to preserve dry
agricultural products.
3. Main contents of the thesis
- Study on fabrication and properties of some polymer blends based on
EVOH (PE/EVOH and PA6/EVOH polymer blends).
- Fabrication and study on properties of gas barrier multilayer polymeric
films based on polymer blends of EVOH.
- Study on application of gas barrier multilayer packaging to preserve
some dry agricultural products (maize, soybeans).
4. Cấu trúc của luận án
The dissertation has 111 pages, including the Preface, Chapter 1:
Overview, Chapter 2: Experiment, Chapter 3: Results and discussions,
Chapter 4: Conclusions, Pubblications, with 29 images, 21 tables and 90
references.
DISSERTATION CONTENTS
CHAPTER 1. LITERATURE REVIEW
In Vietnam, although the share of the agricultural sector in the country's
GDP has decreased in recent years, its contribution to growth has remained
stable at 16-18%. The agricultural still plays an important role when it creates
more than 40% of total employment for the whole country. According to the
World Food and Agriculture Organization (FAO), postharvest losses in
developing countries amount to 20-30%. In our country, the statistics show
that the loss of yield during and after harvest for rice of 11-13%, maize of 13-
15%, concentrated in the stages of harvesting, drying, preserving and milling.
The main cause is due to harvesting, packaging, transport and storage. On the
basis of synthesizing domestic and foreign research documents, it can be seen
that gas barrier storage is an advanced preservation method, widely applied in
the world today. Packaging materials capable barrier of gas, moisture and
solvents are increasingly popular, especially in the field of food preservation
and dry food. However, non-polar hydrocarbon solvents and their mixtures
(such as xylene, toluene, white oil, etc.) can easily seep through the
conventional polymer packaging (PE and PP) to degrade and cause health
and food safety issues. Therefore, combining polymers with specific features
into new polymer materials that have all the preeminent features of the
component polymers, meeting the technical requirements of gas barrier
packaging products are essential. .
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Studies have shown that EVOH has good hydrocarbon barrier
properties and is considered an oxygen barrier in food packaging applications
where oxygen is essential due to its high oil resistance and gas barrier
properties. However, its moisture-absorbing properties, being relatively
brittle and expensive, diminish its advantages. In order to reduce costs while
maintaining good gas barrier properties, studies on polymer blends of EVOH
have attracted a lot of attention in recent years, especially polymer blends of
EVOH with PE and PA6.
In the gas barrier packaging technology, the multi-layer extrusion
technology proved to be effective in improving the poor gas barrier
properties of polyolefin packaging. This technique allows the desired
properties of polymers to be combined into one structure with enhanced
performance. In this way it is possible to take advantage of the inherent
barrier properties and protect the plastic layer from high relatively humidity.
In addition, this plastic layer is also protected from corrosion, avoiding
miscibility problems and improving transparency of film.
In Vietnam, there are no research projects on manufacturing gas-barrier
multilayer polymeric packaging for agricultural preservation applications,
especially dry agricultural products. Therefore, this dissertation chooses the
topic "Study on the manufacturing and properties of gas barrier multilayer
films and applications".
CHAPTER 2. EXPERIMENTS
2.1. Materials and equipments
2.1.1. Materials
Linear low density polyethylene (LLDPE), ethylene-vinyl alcohol
copolymer (EVOH), low density polyethylene graft maleic anhydride (PE-g-
MAH, MAH content of 0,1%), polyamide 6 (PA6), corn seed HQ 2000,
soybean seed DT96.
2.1.2. Equipments
Supermix high-speed mixer, Brabender Plastograph®EC device
(Germany), hydraulic press, LyssyL-100-5000 water vapor permeability
tester, N500 gas permeability tester, plastic SD-35 single screw extruder,
3SJ-G2000 multilayer film blowing device, BP-1068 mechanical measuring
device, Thermo Nicolet Nexus 670 Fourier Transform Infrared
Spectroscopy, differential scanning calorimeter (DSC 204 F1 Phoenix) and a
thermogravimetry analysis system (TGA 209 F1 Libra), SM-6510LV and
JEOL 6490 scanning electron microscope, BZQ 500 vacuum device,
Mitutoyo IP67 electronic film thickness measuring device, scientech scales,
readability 0,001 (g), oven and laboratory equipments.
