Kulkarni Apoorva, Emrich Jakob, Narayan Ramani
Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI 48824, USA.
Polymers (Basel). 2024 Dec 3;16(23):3402. doi: 10.3390/polym16233402.
In this study, water-insoluble, moisture-resistant starch foams were prepared using an optimized one-step extrusion-foaming process in a ZSK-30 twin screw extruder. The extrusion parameters, including temperature, screw configuration, die diameter, water content, and feeding rates, were optimized to achieve foams with the lowest density and controlled expansion. A screw configuration made up of three kneading sections was found to be the most effective for better mixing and foaming. Polyvinyl butyral (PVB) acted as a plasticizer, resulting in foams with a density of 21 kg/m and an expansion ratio of 38.7, while chitosan served as a nucleating agent, reducing cell size and promoting a uniform cell size distribution. The addition of PVB and chitosan reduced the moisture sensitivity of the foams, rendering them hydrophobic and water-insoluble. The contact angle increased from 0° for control foams to 101.5° for foams containing 10% chitosan and 10% PVB. Confocal laser scanning microscopy (CLSM) confirmed the migration of chitosan to the foam surface, enhancing hydrophobicity. Aqueous biodegradation tests, conducted at 30 °C in accordance with ISO 14852 standards, demonstrated that despite enhanced moisture resistance, the foams remained readily biodegradable, achieving approximately 80% biodegradation within 80 days. These modified starch foams present a sustainable solution for packaging and insulation applications that demand long-term humidity resistance.
在本研究中，使用ZSK - 30双螺杆挤出机中优化的一步法挤出 - 发泡工艺制备了水不溶性、防潮淀粉泡沫。对挤出参数，包括温度、螺杆构型、模头直径、含水量和进料速率进行了优化，以获得密度最低且膨胀可控的泡沫。发现由三个捏合段组成的螺杆构型对于更好的混合和发泡最为有效。聚乙烯醇缩丁醛（PVB）用作增塑剂，得到密度为21 kg/m且膨胀比为38.7的泡沫，而壳聚糖用作成核剂，减小泡孔尺寸并促进泡孔尺寸均匀分布。PVB和壳聚糖的添加降低了泡沫的湿度敏感性，使其具有疏水性和水不溶性。接触角从对照泡沫的0°增加到含有10%壳聚糖和10% PVB的泡沫的101.5°。共聚焦激光扫描显微镜（CLSM）证实壳聚糖迁移到泡沫表面，增强了疏水性。按照ISO 14852标准在30°C下进行的水性生物降解试验表明，尽管防潮性增强，但泡沫仍易于生物降解，在80天内实现了约80%的生物降解。这些改性淀粉泡沫为需要长期耐湿性的包装和隔热应用提供了一种可持续的解决方案。
