应用于包装领域的明胶泡沫性能研究

目的 制作和表征基于明胶的生物基可堆肥降解泡沫材料，并应用于包装领域。方法 明胶泡沫通过机械发泡和在周围环境中干燥制成。研究明胶含量、表面活性剂含量以及发泡温度对泡沫最大发泡倍率(MER)、收缩、密度、结构以及压缩性能的影响。此外，研究不同明胶含量样品的导热率。结果 研究的3个因素对泡沫性能和结构有显著影响。MER值和收缩是黏度相关，并极大地影响泡沫密度、力学性能以及热导率。增加明胶含量制造出了密度和压缩强度更高的泡沫(由于MER值更低)。表面活性剂质量分数从0.75%增加到1.5%由于发泡性提升造成泡沫密度轻微下降。然而，进一步将表面活性剂质量分数提升至3%造成黏度显著增加、MER值下降，从而导致泡沫密度增加。更高的发泡温度可以得到更高的MER，但是由于液态泡沫稳定时间更长，收缩程度更大，泡沫密度更大。结论 明胶泡沫展现出作为低密度传统塑料泡沫(密度小于30 kg/m³)环保替代品极具潜力的性能。研究成功实现了明胶泡沫的低热导率〔0.038～0.039 W/(m.K)〕和相对较低的收缩程度。

Properties of Gelatine Foams for Packaging Applications

The work aims to produce and characterise biobased and compostable foams based on gelatine for packaging applications. The gelatine foams were made by mechanical foaming and drying in surrounding environment. The effects of gelatine content, surfactant content and foaming temperature on the maximum expansion ratio (MER), shrinkage, density, structure and compression properties of foams were investigated. In addition, the thermal conductivity of samples prepared with different contents of gelatine was studied. The three factors studied significantly affected the foam properties and structure. MER and shrinkage were viscosity-dependent and considerably affected the foam density, mechanical properties and thermal conductivity. An increase in gelatine content resulted in denser foams and higher compression strength due to lower MER. An increase of surfactant content from 0.75 wt.% to 1.5 wt.% caused a slight decrease in density due to an increase in foamability. However, further surfactant addition up to 3 wt.% led to denser foams due to considerable increase of viscosity and MER decrease. Higher foaming temperature led to higher MER, but because the liquid foam had a longer stability time, the shrinkage degree was larger and foam density was higher. The gelatine foams exhibit promising properties for being an environmentally friendly alternative to conventional low-density plastics foams (<30 kg/m3). The low thermal conductivity 0.038 ~ 0.039 W/(m k)] and relatively low shrinkage of gelatine foams are successfully achieved.