Crimson Publishers Publish With Us Reprints e-Books Video articles

Full Text

Annals of Chemical Science Research

A Study of the Dry Mechanical Properties of a Paper Wrapping Plastic Film

Katerina Chryssou* and Eugenia Lampi

General Chemical State Laboratory, B’ Chemical Division of Athens, Department A’ Tsocha 16, Greece

*Corresponding author:Katerina Chryssou, General Chemical State Laboratory, B’ Chemical Division of Athens, Department A’ Tsocha 16, 11521 Athens, Greece

Submission: December 26, 2024;Published: January 16, 2025

DOI: 10.31031/ACSR.2025.05.000604

Volume5 Issue1
January 16, 2025

Abstract

The determination of dry tensile properties of a paper wrapping plastic film was performed as well as the percent strain at break, the elongation in mm, in both directions, the machine direction, and the counter machine direction. We observed a correlation between stress and tensile strain in % by linear function. Also, the thickness of the plastic film was measured and was found to be 0.16mm. The dry tensile strength in the machine direction increased linearly with decreasing film thickness. The tensile strain at break in % increased linearly with increasing film thickness in the machine direction. The dry tensile strength across the cross-machine direction increased linearly with increasing film thickness. Also, the geometrical mean of the tearing resistance in mN was calculated and was correlated linearly with film thickness. The elongation at break in % in both directions increased as the film thickness increased. Finally, the plastic film was considered isotropic.

Keywords: Paper wrapping thin plastic film; Tensile strength; Thickness; Tearing resistance; Geometrical mean tearing resistance

Introduction

The need for soft, elastic materials to resemble the elastic nature of soft tissues has driven the development of various biodegradable elastomeric polymers in tissue engineering and drug delivery. These materials are mechanically weak with a tensile strength at dry state, not more than 10MPa. Effectively balancing the mechanical properties and biodegradation of the plastic films, especially bio-functionalisation, to regulate cell/tissue biomaterial interactions is a challenge [1]. In general polymer thin films are difficult to be handled, and their mechanical properties have been poorly understood [2]. In this work a paper wrapping plastic film’s dry tensile and other mechanical properties are studied. The tensile properties vary with specimen thickness, specimen width, the rate of grip separation, and the initial gauge length. The tensile properties indicate anyway how well the plastic film can withstand tension [3]. Generally, tensile strength and elongation are seen as important barometers in later estimating photo-degradability, and the ultimate tensile strength and elongation values at the break point would be later statistically compared to determine photo-degradability. Elongation is more closely related to degradability. Changes in average elongation of the test sample toward cross direction (CD), and machine direction (MD) can be tested during periods of UV-irradiation [4].

Materials and Methods

Instruments and materials

Ten or more test pieces 21cm x 1.5cm were cut from the plastic film sample by a guillotine IDEAL 1043 GS. These test pieces were conditioned at 23 °C and 50% RH for 16hr in a conditioning chamber [5]. The tensile testing machine Zwick Roell Z2.5 BT1-FR 2.5th D14/2008, S.N. 181435/2008, was used for measuring the tensile strength [TS (MPa)] and percentage elongation at break (%) [E (%)] and elongation in (mm) of the wrapping plastic film, according to ASTM Standard Method D 882-10 [6]. The machine extended the plastic test pieces at 500mm/min constant rate of elongation (cross head speed), and measured both the tensile force and the elongation produced. Two clamps holded the plastic test pieces of 15mm width and grab them along a straight line across the full width of the plastic test pieces. The initial grip to grip separation was set at 50mm [6].

The thickness of the plastic film sample was measured using the digital precision micrometer TMI Model No 49-61-01-0002, S.N. 33421-01, with range 0-1.270mm. Twenty measurements were made on each test piece of 10cm x 10cm dimensions and mean thickness was calculated [7]. These test pieces were also conditioned at 23 °C and 50% RH for 16hr in a conditioning chamber [5].

The tearing resistance, Elmendorf method, was measured in a Lorentzen & Wettre, Stockholm Sweden, pendulum-type manual tearing tester with serial number 1210, code:009, type:95021, No:5529. The test piece dimensions were 7.6cm x 6.3cm and it was a pack of four rectangular sheets of the same size (7.6cm x 6.3cm), that it was tested according to ISO 1974:2012 [8]. These test pieces were also conditioned at 23 °C and 50% RH for 16hr in a conditioning chamber [5].

Results and Discussion

As in a model where the polymer molecules and the bonds were simplified as homogeneous and isotropic continua, the tensile properties of the plastic film were determined. The method used was specified in ASTM D882-10 [6]. Ten replicates were measured in the machine direction (MD) and eleven replicates were measured in the counter machine direction (CD) [9] (Figure 1).

Figure 1:Tensile force curves in Newton versus strain in mm, for the ten specimens of the paper wrapping plastic film tested in the machine direction (MD), and the relevant statistics.


The elongation at break values, of several hundred found during testing were common for film packaging plastics [10].

In Figure 2 we had correlation between stress and tensile strain in % by a linear function [11].

Figure 2:Linear in plane dry tensile stress-strain curve in the MD direction of a wrapping plastic film (Table 1).


Table 1:MD stress in MPa and the corresponding values of MD strain at break in%, and in mm, of a sample of paper wrapping plastic film [9].


Figure 3:Linear in plane dry tensile stress-elongation at break curve in the MD direction of a wrapping plastic film (Table 1).


Figure 4:Linear dry tensile stress in the MD direction-thickness curve of a wrapping plastic film (Table 2).


Table 2:MD stress in MPa and the corresponding values of thickness in mm, of a sample of paper wrapping plastic film.


The dry tensile strength across the machine direction increased linearly with decreasing polymer film thickness within the film thickness range studied [13].

Tensile strain at break in % increased linearly with increasing film thickness within the range studied (Figure 5 & Figure 6) [14].

Figure 5:Linear dry tensile strain at break in % in the MD direction-thickness curve of a wrapping plastic film (Table 2).


Figure 6:Tensile force curves in Newton versus strain in mm, for the eleven specimens of the paper wrapping plastic film tested in the counter machine direction (CD), and the relevant statistics.


Eleven replicates were measured in the counter machine direction as specified in ASTM D882-10 [6] (Figure 7).

Figure 7:Linear in plane dry tensile strength-strain curve in the CD direction of a wrapping plastic film (Table 3).


The mechanical properties helped us to understand the workability and applicability of the paper wrapping polymer film and were understood in terms of the tensile strength and strain at failure (flexibility) also in the counter-machine direction (CD) [15] (Figure 8).

Figure 8:Linear in plane dry tensile strength-elongation in mm curve in the CD direction of a wrapping plastic film (Table 3).


Table 3:CD stress in MPa and the corresponding values of CD strain at break in%, and in mm, of a sample of wrapping plastic film.


From the results of the tensile tests the conclusion could be drawn that the film with an average thickness of 159μm could be considered isotropic [16].

The tensile strength in the CD direction of the film was offset by the increase in the film thickness [17]. The dry tensile strength across the cross-machine direction (CD) increased linearly with increasing film thickness within the film thickness range studied (Figure 9 & Figure 10).

Figure 9:Linear dry tensile strength in the CD direction-thickness curve of a wrapping plastic film (Table 4).


Figure 10:Linear dry tensile strain at break in % in the CD direction-thickness curve of a wrapping plastic film (Table 3 and Table 4).


Table 4:CD stress in MPa and the corresponding values of thickness in mm, of a sample of wrapping plastic film.


Tearing was one of the most critical mechanical properties of polymeric films. The tearing process of ductile films was very similar to the tensile process because of the large deformation in the direction of loading [18,19].

The performance of the Elmendorf tearing test was an important end-use test of the plastic film and was used to determine the range of the film application, as well as the price of the film-grade resin, and to compare polymerization catalysts, and also the processes employed for the synthesis of the respective polymer [20].

The tearing strength depended strongly on the thickness of the film, as could be seen in Figure 11.

Figure 11:Geometrical mean tearing versus thickness curve, of a wrapping plastic film (Table 5).


Table 5:MD Tearing in mN and CD tearing in mN, Geometrical mean tearing, and the corresponding values of thickness in mm, of a sample of wrapping plastic film [19].


Conclusion

The elongation at break in % (E) values for the film varied linearly with the tensile strength in MPa (TS). The elongation at break (%) (E) in general increased as the film thickness increased, so in general comparison of (E) should also include film thickness. No anisotropy effect was observed. Isotropy was expected and, was observed, since there was the same molecule orientation in all directions of the plastic film.

References

  1. Jinshan Guo, Zhiwei Xie, Richard T Tran, Denghui Xie, Dadi Jin, et al. (2014) Click chemistry plays a dual role in biodegradable polymer design. Adv Mater 26(12): 1906-1911.
  2. Hiroki Hasegawa, Takashi Ohta, Kohzo Ito, Hideaki Yokoyama (2017) Stress-strain measurement of ultra-thin polystyrene films: Film thickness and molecular weight dependence of crazing stress. Polymer 123: 179-183.
  3. Milton Ohring (2002) Tensile testing, Chapter 12-Mechanical properties of thin films. Materials Science of Thin Films (Second Edition), pp. 711-781.
  4. Myong-Soo Chung, Wang-Hyun Lee, Young-Sun You, Hye-Yoang Kim, Ki-Moon Park, et al. (2006) Assessment and application of multi-degradable polyethylene films as packaging materials. Food Sci Biotechnol 15(1): 5-12.
  5. ISO 187 (2022) Paper, board and pulps-standard atmosphere for conditioning and testing and procedure for monitoring the atmosphere and conditioning of samples, (3rd edn), pp. 1-7.
  6. ASTM D882-10 (2010) Standard test method for tensile properties of thin plastic sheeting, pp. 1-8.
  7. International Standard, ISO 534 (2011) Paper and board-Determination of thickness, density, and specific volume, pp. 1-13.
  8. International Standard, ISO 1974 (2012) Paper-Determination of tearing resistance-Elmendorf method, pp.1-13.
  9. Park JW, Testin RF, Park HJ, Vergano PJ, Weller CL (1994) Fatty acid concentration effect on tensile strength, elongation, and water vapor permeability of laminated edible films. J Food Sci 59(4): 916-919.
  10. Ahmed M El-hadi (2017) Increase the elongation at break of poly(lactic acid) composites for use in food packaging films. Sci Rep 7: 46767.
  11. Mohammad Amjadi, Ali Fatemi (2020) Tensile behavior of high-density polyethylene including the effects of processing technique, thickness, temperature, and strain rate. Polymers 12(9): 1857.
  12. Damian Palomba, Gustavo E Vazquez, Monica F Diaz (2014) Prediction of elongation at break for linear polymers. Chemom Intell Lab Syst 139: 121-131.
  13. Cholwasa Bangyekan, Duangdao Aht-Ong, Kawee Srikulkit (2006) Preparation and properties evaluation of chitosan-coated cassava starch films. Carbohydr Polym 63(1): 61-71.
  14. Seyyedvahid Mortazavian, Ali Fatemi (2015) Effects of fiber orientation and anisotropy on tensile strength and elastic modulus of short fiber reinforced polymer composites. Compos Part B: Engineering 72: 116-129.
  15. Harpreet Kaur, Tarlok Singh Banipal, Sourbh Thakur, Mandeep Singh Bakshi, Gurinder Kaur, et al. (2013) Novel biodegradable films with extraordinary tensile strength and flexibility provided by nanoparticles. ACS Sustain Chem Eng 1(1): 127-136.
  16. Velzen ER (1990) Determination of the tensile properties of Upilex-R thermoplastic polyimide film. Delft University of Technology, Department of Aerospace Engineering, Materials and Structures.
  17. Jung-Soo Lee, Min A Park, Chan Suk Yoon, Ja Hyun Na, Jaejoon Han (2019) Characterization and preservation performance of multilayer film with insect repellent and antimicrobial activities for sliced wheat bread packaging. J Food Sci 84(11): 3194-3203.
  18. Byoung Ho Choi, Mehmet Demirors, Rajen M Patel, Willem de Groot A, Kenneth W Anderson, et al. (2010) Evaluation of the tear properties of polyethylene blown films using essential work of fracture concept. Polymer 51(12): 2732-2739.
  19. Nizam Uddin Md, Zhen-Dong Huang, Yiu-Wing Mai, Jang-Kyo Kim (2014) Tensile and tearing fracture properties of graphene oxide papers intercalated with carbon nanotubes. Carbon77: 481-491.
  20. Yury V Kissin (2011) Elmendorf tear test of polyethylene film: Mechanical interpretation and model. Macromol Mater Eng 296(8): 729-743.

© 2025 Katerina Chryssou. This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and build upon your work non-commercially.

About Crimson

We at Crimson Publishing are a group of people with a combined passion for science and research, who wants to bring to the world a unified platform where all scientific know-how is available read more...

Leave a comment

Contact Info

  • Crimson Publishers, LLC
  • 260 Madison Ave, 8th Floor
  •     New York, NY 10016, USA
  • +1 (929) 600-8049
  • +1 (929) 447-1137
  • info@crimsonpublishers.com
  • www.crimsonpublishers.com