ABSTRACT This research investigates the application of near‐infrared (NIR) laser heating technology applied to polyethylene terephthalate (PET) and polypropylene (PP) preforms to mitigate the high energy consumption and low efficiency associated with conventional halogen lamp heating. Compared to traditional methods, NIR laser heating exhibits significant advantages in terms of both spectral selectivity and angular directivity of the radiation. In this study, the laser beam was successfully shaped and homogenized into a uniform spot using a customized optical system based on a segmented freeform mirror. The photothermal transfer process was simulated based on fundamental principles, including the Beer–Lambert law, employing finite element analysis. Experimental results demonstrate that laser heating allows for the control of the outer‐to‐inner surface heating rate ratio of PET sheets at 1.24, which falls within the acceptable range for the stretch blow molding process. Furthermore, a surface morphology engineering strategy, utilizing the light trapping effect induced by surface microstructures, was implemented to enhance the optical absorption properties of both PET and PP materials. This strategy leads to a 26.9% increase in the absorptance of PET preforms and a further 25% improvement in heating efficiency, thereby effectively elevating the photothermal conversion efficiency during the laser heating process. Crucially, the proposed system radicalizes energy efficiency, achieving an energy‐saving ratio of over 75% by reducing power consumption from 20 kW in traditional ovens to below 5 kW. This work demonstrates considerable application potential within the plastic packaging industry for technological upgrading and sustainable development.
Lin et al. (Sat,) studied this question.