Effect of x-ray irradiation on the physical properties of polyvinyl chloride

 TẠP CHÍ KHOA HỌC HO CHI MINH CITY UNIVERSITY OF EDUCATION 
 TRƯỜNG ĐẠI HỌC SƯ PHẠM TP HỒ CHÍ MINH JOURNAL OF SCIENCE 
 Tập 18, Số 3 (2021): 395-402 Vol. 18, No. 3 (2021): 395-402 
 ISSN: 
 1859-3100 Website:  
 Research Article* 
 EFFECT OF X-RAY IRRADIATION 
 ON THE PHYSICAL PROPERTIES OF POLYVINYL CHLORIDE 
 Hoang Van Ngoc1, Nguyen An Son2*, Le Viet Huy2, Nguyen Thi Minh Sang2, 
 Le Thi Thanh Tran2, Do Thi Le2 and Nguyen Thi Phuc2 
 1Thu Dau Mot University, Vietnam 
 2Dalat University, Vietnam 
 *Corresponding author: Nguyen An Son – Email: sonna@dlu.edu.vn 
 Received: October 17, 2020; Revised: December 23, 2020; Accepted: December 30, 2020 
ABSTRACT 
 In this investigation, the MBR-1618R-BE (Hitachi, Japan) machine is used to generate X-rays. 
Low energy X-rays vary with energies 0.5 kGy, 1.0 kGy, 5 kGy, and 10 kGy radiation level, and time 
is 7.83 minutes, 15.75 minutes, 78.73 minutes, and 157.46 minutes respectively. This research 
investigates the effect of X-ray irradiation doses on the physico-chemical properties of PVC. PVC 
samples before and after irradiation are transferred in liquid form by using microwave digestion 
Mars 6 and then X-ray Powder Diffraction (XRD) to determine the structural morphological 
characteristics of PVC samples. XRD results show that the change of PVC polymer structure depends 
significantly on a radiation dose. At the diffraction peaks of angles 17.670 and 26.170, the count at 
the peak region decreases sharply at a low projection dose at 0.5 kGy and 1 kGy, and in this region, 
the structural change according to the projection dose takes the form of a linear superlative function. 
With higher energy from 1 kGy to 10 kGy, the effect on the PVC structure changes gradually. The 
study results show that the application of radiation in PVC destruction can be applied to reduce the 
decomposition time. It also results in less waste disposal to the environment. 
 Keywords: Polyvinyl Chloride (PVC); X-ray irradiation; X-ray dose; XRD 
1. Introduction 
 In recent years, Polyvinyl Chloride (PVC) has become one of the most widely used 
resins. Such plastic materials as packaging, home furnishings, children's toys, auto parts, 
construction materials, and hospital supplies are made from PVC. PVC is flexible, easy to 
manipulate, and cheap. However, PVC plastic is one of the biggest pollutants for the 
environment. PVC has a lifespan of more than 50 years when buried underground. 
 PVC was firstly produced in 1872 by Baumann et al. (1872). When the tube containing 
vinyl chloride (VCM) was exposed under sunlight, it was resulted in a white powder, which 
Cite this article as: Hoang Van Ngoc, Nguyen An Son, Le Viet Huy, Nguyen Thi Minh Sang, Le Thi Thanh Tran, 
Do Thi Le, & Nguyen Thi Phuc (2021). Effect of X-ray irradiation on the physical properties of Polyvinyl 
Chloride. Ho Chi Minh City University of Education Journal of Science, 18(3), 395-402. 
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 HCMUE Journal of Science Vol. 18, No. 3 (2021): 395-402 
is due to the polymerization of a single VCM particle (CH2 = CHCl). Chlorine in PVC 
accounts for 57% of the weight of pure polymer resins. Fig. 1 shows the molecular structure 
of VCM and PVC. 
 Vinyl clorua Polyvinyl clorua 
 Fig. 1. The molecular structure of VCM and PVC 
 A large-scale study involving 15 European countries (EU-15) and six other countries 
was carried out, and predictions were made for PVC waste between 2000 and 2020 (Brown 
et al., 2000). During this period, post-consumer PVC waste accounts for about 88% of the 
total PVC waste, which is expected to increase from 3.6 to 6.4 million tons per year among 
these countries. The study points out that PVC waste is a serious issue in all over the world. 
Therefore, it is necessary to restrict the use of PVC materials and find out the treatment to 
reduce the lifespan of the materials containing PVC compounds. 
 Up to date, the treatments of PVC waste are by burial or reuse. By using irradiation, 
there have also been studies of the effects of radiation. In which, the most common is the 
manipulation of gamma radiation (Waly, et al., 2018; Younes et al., 2019; Dang et al., 2018; 
Polvi et al., 2013). All of these studies were aimed to determine the effect of irradiation on 
the polymer structure, with the advantage of high-energy gamma-ray and relatively high 
dose rates. Thus, the obtaining results were asymptotic to the saturation dose rate in short 
irradiation time. However, the disadvantage is that using a radioactive source requires an 
assurance of safety, such as shielding system. 
 In Vietnam, the study of the irradiation effects on the lifespan of PVC materials has 
rarely been conducted. Chemical methods have been implemented, but these have not been 
widely applied. Recently, not only in Vietnam but also in the world, there have been studies 
of using PVC materials in biology as well as day life equipment. 
 In this study, we aim to estimate the effect of X-ray irradiation in the structure of PVC 
material, aiming to reduce the lifespan of the material and enhance the environmental waste 
treatment. 
2. Materials and method 
2.1. Sample preparation and irradiation setup 
 PVC samples used for the study are unused plastic bags, which was cut into circular 
plates with 200 mm in diameter and 0.02 mm in thickness. A set of 10 pieces stacked up was 
subjected for each irradiation (total thickness equal to 0.2 mm). PVC samples were irradiated 
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by an X-ray generator MBR-1618R-BE (Hitachi). Fig. 2 presents the PVC sample and the 
X-ray generator. 
 The X-ray generator MBR-1618R-BE (Hitachi) is currently used for materials 
research, food preservation, microorganism killing, and gene mutation. The generator 
operates in the voltage range of 35-160 kV, and the current range is about 1-30 mA (Manual 
for users). 
 a) b) 
 Fig. 2. a) PVC sample; b) MBR-1618R-BE X-ray generator and cooling system 
 Samples were placed in the irradiation chamber inside the X-ray generator. The dose rate 
depends on the distance from the turn able to the X-ray tube. The dose rates at 150 mm, 250 
mm, and 500 mm are 18.45 Gy/min, 11.05 Gy/min, and 1.81 Gy/min, respectively. 
 The diameter of the irradiation area is dependent on the irradiation angle (Fig. 3). The 
diameters of the irradiated area at the height of 150 mm, 250 mm, and 500 mm are 160mm, 
255 mm, and 435 mm respectively. 
 1: X-ray source, 2: PVC sample position 
 b) 
 a) 
 Fig. 3. a) Irradiation chamber of the MBR-1618R-BE X-ray generator; 
 b) Dependence of irradiation angle to the distance of the X-ray source 
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 In this study, the distance from the PVC sample to the X-ray source is 250 mm. Table 
1 presents some irradiation parameters. 
 Table 1. PVC irradiation parameters 
 Amount Voltage 
 Distance from 
 of (V) and Dose rate Irradiation Total 
 No. PVC sample to X-
 samples current (Gy/mmAir) time (mins) dose(kGy) 
 ray source(mm) 
 (plates) (mA) 
 100 kV; 
 1 250 10 63.51 7.83 0.5 
 30 mA 
 100 kV; 
 2 250 10 63.51 15.75 1 
 30 mA 
 100 kV; 
 3 250 10 78.73 5 
 30 mA 
 100 kV; 
 4 250 10 63.51 157.46 10 
 30 mA 
2.2. Method 
 In order to estimate the material structure change, the samples were measured by X-
ray diffraction imaging. The X-ray diffraction properties through crystals follow the Bragg's 
law: 
 2 θ = λ (1) 
here: λk is the wavelength of X-ray diffraction, d is the distance between the lattice nodes, θ 
 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑 𝑘𝑘 𝑘𝑘
is the diffraction angle, and k (k = 1, 2, 3,...) is the diffraction order. 
 To evaluate the effectiveness of PVC structural deformation, the determination of the 
spectral peak area at the maximum diffraction was carried out. The percentage (relative ratio) 
of transformed PVC was calculated by comparing to the intensity of diffraction peaks of the 
un-irradiated PVC sample. 
3. Results and discussion 
 Pre-irradiated and post-irradiated PVC samples were measured by XRD to assess 
structural changes, using the XRD Bruker D8 system, with the X-ray wavelength λCuKα1= 
1.5406 Å. In pristine, samples were homogenized by microwave digestion. In this study, the 
MARS 6 digestion system was used, and the fineness of the sample after digestion reached 
<50 µm. Fig. 4 shows the XRD spectrum of the PVC sample before irradiation. 
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 HCMUE Journal of Science Hoang Van Ngoc et al. 
 Fig. 4. Spectrum of PVC sample before irradiation 
 XRD results show that there are two diffraction peaks corresponding to the diffraction 
angle 2θ: 17.670 and 26.170. This result is consistent with previous studies (Brunner, 1972; 
Altenhofen et al., 2011). Using formula (1) to calculate the node distance, the results are 
presented in Table 2. 
 Table 2. Bonding parameters of PVC samples 
 Diffraction peak 2θ d (Å) 
 1 17.67 5.015 
 2 26.17 3.402 
 Compare and evaluate XRD spectrum before and after irradiation 
 Fig. 5 shows the XRD spectra of PVC samples before and after irradiation for various 
doses. For un-irradiated PVC samples, the diffraction peaks at angles of 17.670 and 26.170 
are clear. When X-ray irradiation is conducted with different dose rate from 0.5 kGy ÷ 10 
kGy, the diffraction spectrum is obtained as illustrated in Fig. 3b, 3c, 3d and 3e. Visually, 
the decrease of diffraction intensity at the two peaks can also be seen. This means that 
networks with distances between the nodes of 5.015 Å and 3.402 Å are significantly reduced 
when the dose increases. 
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 Fig.5. XRD spectrum of PVC samples before and after irradiation 
 To evaluate the number of structural changes of PVC samples before and after 
irradiation, the relative intensity at the two diffraction peaks was used with various 
irradiation doses. The relative intensity was calculated as the total count on the area of the 
angular difference from 15.10 to 26.430, as shown in Table 3. 
 Table 3. Changing rate of PVC structure by X-ray dose rate 
 Un-
 0.5 kGy 1 kGy 5 kGy 10 kGy 
 Net peak area irradiated 
 19154 17719 16076 10074 7998 
 % change in structure 0% 7.49% 16.07% 47.41% 58.24% 
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 HCMUE Journal of Science Hoang Van Ngoc et al. 
 The results show that the changing rate of PVC structure is dependent on the irradiation 
dose. At low doses, there are less variation. However, the change of PVC structure is not 
followed the linearity rule, for example, when the dose was increased from 0.5 kGy to 1 kGy 
(increased by 2 times), the PVC structure changes increased by ~ 2.145 times. However, 
when the dose was continuously increased from 1 kGy to 5 kGy and 10 kGy (5 times and 10 
times, respectively), the structure of PVC changed 2.95 times and 3.624 times, respectively. 
4. Conclusion 
 In this study, the modification in PVC structure was implemented by using low-energy 
X-ray radiation, with the range of 0.5 kGy to 10 kGy. The diffraction imaging was applied 
to assess the changes in PVC structure with respect to irradiation dose. From the XRD 
results, there was a sharp change in PVC structure in the dynamic survey dose range. This 
result can be applied to polymer waste treatment, by reducing its decomposition time, thus 
contributing for environmental protection. The study has met two main objectives: 
 - Study of irradiation effect on PVC polymers: the breakdown of polymer bonding 
structure using low energy X-rays. 
 - Quantitative assessment of the degree of irradiation effect on the structure of PVC. 
 In addition, the experimental data with mean dose rate and irradiation time of X-ray 
irradiation will also bring economic benefits to the future commercial irradiation process. 
  Conflict of Interest: Authors have no conflict of interest to declare. 
  Acknowledgement: The authors wish to thank Thu Dau Mot University for the fund to this work. 
 We also wish to thank the Faculty of Physics and Nuclear Engineering – Dalat University, for 
 the operation of X-rays irradiator MBR-1618R-BE (Hitachi Power Solutions, Japan). 
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 plasticizer obtained through polyesterification of rice fatty acid. Polymer Testing, 30(5), 478-
 484. https://doi.org/10.1016/j.polymertesting.2011.03.008 
Baumann, E., Ann (1872). Ueber einige Vinylverbindungen. In: Ann. Chem. Pharm., 163(3), 
 308-322 
Brown, K. A., Holland, Boyd, M. R., Thresh, S., Jones, H., & Ogilvie, S. M. (2000). Economic 
 Evaluation of PVC Waste Management. AEA Technology 
Brunner, A. J. (1972). X-ray diffraction pattern of poly(vinyl chloride). Journal of Polymer Science 
 Part B: Polymer Letters, 10(5), 379-383. https://doi.org/10.1002/pol.1972.110100509 
Dang, W., Liu, J., Huang, X., Liang, J., Wang, C., Miao, P., An, Y., & Wang, X. (2018). Effects of 
 γ-ray irradiation on the radial structure heterogeneity in Polyacrylonitrile fibers during thermal 
 stabilization. Polymers, 10(9), 943. https://doi.org/10.3390/polym10090943 
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Manual for user “Operation manual X-rays irradiation system MBR-1618R-BE” 
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 Instruments and Methods in Physics Research Section B: Beam Interactions with Materials 
 and Atoms, 312, 54-59. https://doi.org/10.1016/j.nimb.2013.07.002 
Waly, S., Shehata, M., & Mahmoud, H. (2018). Effect of gamma irradiation on the physical and 
 chemical properties of copper-poly vinyl Pyrolidone composite films. Arab Journal of Nuclear 
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Younes, M., Abdel-Rahman H. A., & Hamed, E. (2019). Effect of Gamma-Irradiation on Properties 
 of Polymer/Fibrous/Nanomaterials Particleboard Composites, J. Chem. Soc. Pak., 41(6), 
 966-974. 
 ẢNH HƯỞNG CỦA CHIẾU XẠ TIA X LÊN CÁC TÍNH CHẤT VẬT LÍ 
 CỦA VẬT LIỆU POLYVINYL CHLORIDE 
 Hoàng Văn Ngọc1, Nguyễn An Sơn2*, Lê Viết Huy2, 
 Nguyễn Thị Minh Sang2, Lê Thị Thanh Trân2, Đỗ Thị Lệ2, Nguyễn Thị Phúc2 
 1Trường Đại học Thủ Dầu Một, Việt Nam 
 2Trường Đại học Đà Lạt, Việt Nam 
 *Tác giả liên hệ: Nguyễn An Sơn – Email: sonna@dlu.edu.vn 
 Ngày nhận bài: 17-10-2020; ngày nhận bài sửa: 23-12-2020, ngày chấp nhận đăng: 30-12-2020 
TÓM TẮT 
 Trong nghiên cứu này, chúng tôi sử dụng máy phát tia X MBR-1618R-BE (Hitachi) phát tia X 
năng lượng thấp với liều chiếu 0.5 kGy, 1.0 kGy, 5 kGy và 10 kGy tương ứng thời gian chiếu 7.83 
phút, 15.75 phút, 78.73 phút và 157.46 phút để khảo sát ảnh hưởng của liều chiếu xạ tia X lên tính 
chất hóa lí trên vật liệu PVC. Các mẫu trước và sau chiếu xạ được hóa lỏng bằng phá mẫu vi sóng 
Mars 6 và chụp ảnh nhiễu xạ tia X (XRD) để xác định đặc điểm hình thái cấu trúc của mẫu PVC. 
Kết quả chụp XRD cho thấy sự thay đổi của cấu trúc polymer PVC phụ thuộc mạnh vào liều chiếu 
xạ. Tại các đỉnh cực đại nhiễu xạ của các góc 17.670 và 26.170, số đếm tại vùng đỉnh suy giảm mạnh 
ở liều chiếu thấp tại 0.5 kGy và 1 kGy. Trong vùng này, sự thay đổi cấu trúc theo liều chiếu có dạng 
hàm tuyến tính bậc nhất. Trong vùng liều chiếu lớn hơn (từ 1 kGy đến 10 kGy), ảnh hưởng lên sự 
thay đổi cấu trúc PVC giảm dần. Kết quả nghiên cứu cho thấy, việc ứng dụng bức xạ trong phá hủy 
PVC có thể được ứng dụng để giảm thời gian phân hủy và ứng dụng trong xử lí rác thải ra 
 môi trường. 
 Từ khóa: Polyvinyl Clorua (PVC); chiếu xạ tia X; liều chiếu tia X; XRD 
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