What is pl？

Core Properties and Production Process of PL

1. Raw Material Sources

    

   The core feedstocks of PL are renewable biomass, most commonly starch-rich crops such as corn, cassava and sugarcane (agricultural wastes like straw can also be utilized). Starch is converted into lactic acid through fermentation, which is then used as the monomer for polymerization.
    
2. Production Process

    

   The industrial production of PL mainly involves two core steps: the first is lactic acid purification, which refines lactic acid derived from starch or sugars into high-purity lactic acid; the second is polymerization reaction, with the mainstream process being lactide ring-opening polymerization—lactic acid is first dehydrated to form lactide, which then undergoes ring-opening polymerization under the action of a catalyst to produce polylactic acid (PL). Subsequent secondary processing, including pelletizing, extrusion, injection molding and film blowing, yields a variety of finished products.
    
3. Key Properties

    

   Its core advantage is complete biodegradability: under industrial composting conditions (temperature 55–70°C, suitable humidity and microbial participation), it can be fully decomposed into carbon dioxide and water, returning to nature without environmental residues. It also exhibits good mechanical strength, transparency and processability, comparable to traditional plastics (e.g., polyethylene, polypropylene). However, it has poor heat resistance (heat deflection temperature around 55–60°C) and low-temperature toughness, which can be improved through modification methods such as blending and fiber reinforcement.
    
4. Application Scenarios

    

   PL is mainly used in disposable eco-friendly products, packaging materials and biomedical fields, such as disposable tableware, food packaging films, shopping bags, biodegradable mulch films, as well as medical sutures and tissue engineering scaffolds (medical-grade PL must meet higher standards for purity and biocompatibility).
    

Core Differences Among PL, PEL, PAL and Bio-based Nylon

1. Molecular Structure Differences
    
   • PL: The main chain has ester bonds as repeating units, with a polylactic acid homopolymer structure.
   • PEL: The main chain has ester bonds as repeating units, belonging to a polyester elastomer structure (containing flexible segments).
   • PAL: The main chain consists of amide bonds (rigid segments) + elastomer segments (flexible segments), with a copolymerized polyamide elastomer structure.
   • Bio-based nylon: The main chain only contains amide bonds as repeating units, with a rigid polyamide structure.
    
2. Performance Focus Differences
    
   • PL: Core strengths are complete biodegradability + good processability, with moderate rigidity, no elasticity and poor heat resistance.
   • PEL: Core strengths are high elasticity + degradability, with the best elastic recovery rate but the weakest rigidity.
   • PAL: Core strength is a balance between rigidity and elasticity, with higher strength and wear resistance than PEL, and better elasticity than bio-based nylon.
   • Bio-based nylon: Core strengths are high strength + high wear resistance + oil resistance, with the highest rigidity, the poorest elasticity and better heat resistance than the other three.
    
3. Application Scenario Differences
    
   • PL: Suitable for disposable eco-friendly products, packaging materials and basic medical supplies (scenarios with no elasticity requirements).
   • PEL: Suitable for eco-friendly scenarios requiring high elasticity (e.g., degradable elastic packaging films, biomedical elastic components).
   • PAL: Suitable for eco-friendly scenarios requiring both strength and elasticity (e.g., automotive elastic structural parts, high-end stretch fabrics).
   • Bio-based nylon: Suitable for eco-friendly structural part scenarios requiring high strength, rigidity and oil resistance (e.g., automotive parts around engines, gears and bearings).