The impact strength of polypropylene resin is an important property index. Before using a cantilever beam to measure the impact strength of polypropylene resin, the test spline needs to be injection molded and V-shaped incision made. The article uses two different melting indexes of random copolymer polypropylene resin. By adjusting the injection molding conditions and the notch strength of the spline opening by incision machine, The effects of injection molding conditions and opening depth, incision radian and curvature radius of incision root on the Izod impact strength of two kinds of random copolymer polypropylene were investigated in order to provide a basis for correctly evaluating the impact strength of plastic materials. The results show that the Izod impact strength of random copolymer polypropylene can be improved by reducing the melting temperature of polypropylene, reducing the injection speed and injection pressure, and reducing the holding time. Different opening machines are used to open the injection molded spline, which has a great influence on the impact strength of the spline, and the impact strength of the two polypropylene resins has the same change trend. The shallower the notch depth, the larger the radius of the root curvature, the larger the notch angle, the more concentrated the stress and strain at the notch, and the greater the Izod impact strength of the random copolymer polypropylene.

The aim of this study was to investigate the effects of different particle sizes (small particle size 777A, large particle size T84) of talc powder on the mechanical properties and heat resistance performance of PE composites by enhancing modified polyethylene (PE) with different particle sizes of talc powder. The results showed that the working properties, mechanical properties and heat resistance performance of PE composites were effectively improved by adding different particle sizes of talc powder. When the content of 777A and T84 talc powder was 15%, the melt flow rate of the PE composites prepared by them were 5.93, 6.01 g/10 min, respectively, the apparent densities were 1.011, 1.128 g/cm³, respectively the tensile strength were 28.21, 29.56 MPa, respectively, and the Vicat softening temperature were 89, 92 ℃, respectively. The improvement effect of PE composites prepared by T84 talc powder with larger particle size is the best.

Poly(lactic acid) (PLA) is considered one of the most promising sustainable bio-based polymers due to its renewability, biodegradability, excellent biocompatibility, high rigidity, high strength, and good processability. However, its inherent brittleness and poor ductility limit its widespread application. Researchers have focused on toughening PLA through various materials. Specifically, the research on toughening PLA using biodegradable materials has garnered significant attention and has achieved a series of important results. The article briefly introduces the synthesis and toughening mechanisms of PLA, and then reviews the latest research progress on the toughening of PLA using various biodegradable materials such as poly(butylene adipate-co-butylene terephthalate) (PBAT), poly(butylene succinate) (PBS), poly(butylene succinate-co-butylene adipate ) (PBSA ), poly (ε-caprolactone) (PCL), polyhydroxyalkanoates (PHA), poly (3-hydroxybutyrate ) (PHB), starch and lignin, etc., discusses the key factors and related toughening mechanisms, and finally points out the challenges and future development directions of toughening PLA with biodegradable materials. The review aims to provide some useful suggestions and guidance for subsequent sustainable research on toughening of PLA.