What are the sensitivities of biodegradable tableware to humidity and temperature during production

Main Material Characteristics of Degradable Tableware
The raw materials for degradable tableware primarily include polylactic acid (PLA), modified polylactic acid (CPLA), polybutylene adipate/terephthalate (PBAT), starch-based composites, and pulp molding materials. These materials are generally hydrophilic or heat-sensitive in their molecular structures, resulting in stringent requirements for humidity and temperature during the production process. The raw materials' hygroscopicity and thermal stability determine the parameters of production equipment and influence the product's molding quality and performance.

The Impact of Humidity on the Production Process
Humidity is a critical factor in the production of degradable tableware. Many bio-based polymer raw materials, such as PLA and starch-based composites, are highly hygroscopic. In high humidity environments, these raw materials readily absorb moisture from the air, causing molecular chain hydrolysis and reducing molecular weight, thereby affecting the mechanical properties and heat resistance of the finished product.

During the injection molding or extrusion process, excessively high moisture content in the raw materials can easily lead to defects such as bubbles, silver streaks, and surface unevenness, impairing the tableware's appearance. Humidity control is even more critical for pulp-molded tableware. During the molding process, the slurry's moisture content must be maintained within an appropriate range. Excessive humidity will require longer drying time after the tableware is formed; insufficient humidity can weaken the fiber bonding and lead to brittle cracking.

Therefore, humidity control directly impacts production efficiency and product quality. Pre-drying of raw materials is typically required during production to keep the moisture content within a specified range to ensure the stability of the physical properties of biodegradable tableware.

The Impact of Temperature on the Production Process

Temperature is another crucial parameter. Different biodegradable materials have significantly different suitable temperature ranges for thermal processing. For example, PLA has a glass transition temperature between 55°C and 60°C, and a melting point between 160°C and 180°C. If the temperature is too low, PLA will not fully melt, resulting in insufficient fluidity and weld marks on the tableware surface. If the temperature is too high, the PLA molecular chains may thermally degrade, releasing lactic acid monomers, resulting in reduced product strength and yellowing.

PBAT has better thermal stability than PLA, but it also decomposes at high temperatures. Temperature control is particularly important for starch-based composites. Excessively high temperatures may cause starch granules to over-gelatinize, affecting the structural strength of the tableware; excessively low temperatures can result in incomplete molding. The hot pressing process for pulp molded products typically requires temperatures between 180°C and 220°C. Instantaneous temperature control can easily lead to deformation or surface roughness.

Temperature control not only affects molding results but also directly affects production energy consumption and costs. Properly setting the temperature range can improve production efficiency while ensuring product quality.

The Synergistic Effect of Humidity and Temperature

In actual production, humidity and temperature often interact with each other. Under high humidity conditions, residual moisture in the raw materials evaporates rapidly during high-temperature processing, creating bubbles and voids, which degrades the mechanical properties of the tableware. Excessively high temperatures accelerate moisture evaporation, easily causing surface cracks or internal holes.

In pulp molded tableware production, the balance of humidity and temperature is particularly important. The molding process requires high temperatures to shape and solidify the fibers, and the moisture in the pulp must be controlled and evaporated during the appropriate drying stage. If the humidity and temperature are not properly balanced, the finished tableware may experience uneven shrinkage, warping, and even partial charring. Therefore, manufacturers typically establish strict humidity and temperature monitoring systems, using automated control equipment to adjust processing conditions in real time to ensure product consistency and stability.

Quality Control and Process Optimization Directions
In the production of biodegradable tableware, humidity and temperature sensitivity present quality control challenges while also driving the development of process optimization. Companies typically implement the following measures to ensure product performance:
Pre-drying raw materials to ensure moisture content is below safety standards;
Precisely setting processing temperature ranges to prevent overheating and degradation;
Using automated monitoring systems to achieve a dynamic balance between humidity and temperature;
Optimizing cooling and drying processes to reduce stress concentration and deformation.