**4.1 Applications of recycled HDPE**

*Thermosoftening Plastics*

functional group dictates chemical reaction between the polymers and modifier, resulted to change in absorption peak correlate change in strength and modulus of

*FTIR of recycled thermoplastics (a) HDPE [29], (b) LDPE [30], (c) PCV [29], (d) PET [29], and (e) PP [29].*

The scanning electron microscopy depicts the morphology of virgin and recycled thermoplastics at fracture surfaces when stressed and characterized the ductile, toughness, stiffness, and brittle nature of HDPE, LDPE, PCV, PET, and PP without modification [32], but improvement in compatibility using EPDM compatibilizer has been reported [2, 70]. The improvement in rheological morphology does not indicate an improvement in compatibility as well as mechanical properties [71]. Modification of recycled HDPE with treated natural fiber using NaOH, SLS, acetic anhydride, CaCO3 filler, and zeolites as well as synthetic fibers is characterized with improvement in polymer dispersion, even distribution of fibers, interfacial adhesion, fiber tearing, micro-crack formation, modifier content and size, nature of the modifier, and reduction in void formation [20, 43, 72–75]. This indicated the enhanced compatibility which corroborates the improvement in physical, mechanical, and thermal properties of the modified

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the thermoplastics.

**Figure 3.**

**3.2 Scanning electron microscopy**

recycled thermoplastics and dictates its applications.

The application of the HDPE composites is a function of the favorable properties coupled with cost implication of the production, and it may be affected by additional modified agents such as fiber or filler, NaOH, acetic anhydride, zeolite, and sodium lauryl sulfate. The use of recycled HDPE composites has been reported for many applications such as packaging (food storage containers and bottles for milk jugs) [13, 28, 38], banners, swimming pool installation, corrosion protection for steel pipelines, folding chairs and tables, electrical and plumbing boxes, plastic surgery (skeletal and facial reconstruction) [27], modified asphalt for pavement and road construction [29, 59, 75], housewares, industrial wrapping and gas pipes [30], and storage sheds, enhancing the economic, health, and social values as well as minimizing environmental issues that might be posed by HDPE disposal [38]. Applications of recycled HDPE in the encapsulation of radioactive, hazardous, and mixed wastes have been reported by Lageraaen and Kalb [76].
