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<p>Starch-based plastics offer a sustainable alternative to conventional polymers, but their practical use remains limited due to low mechanical strength and high moisture sensitivity. This study presents a systematic comparison of thermosetting plastics derived from dialdehyde starches (DAS) prepared from six botanical sources, rice, sago, cassava, corn, potato, and pineapple, with particular emphasis on the valorization of pineapple stem starch, an abundant agricultural waste. All starches were converted into dialdehyde starch via aqueous periodic acid oxidation, aldehyde contents of approximately 30–34%. The DAS powders were plasticized with 40 wt% glycerol and processed by hot compression molding to yield thermoset-like materials, likely through acetal and hemiacetal linkages. Compared with thermoplastic starches fabricated from native starch (modulus ≈ 56–64&#xa0;MPa; tensile strength ≈ 2–4&#xa0;MPa), the DAS-based thermosets exhibited markedly improved mechanical properties, with modulus values of ~ 1200–1900&#xa0;MPa and tensile strengths of ~ 19–42&#xa0;MPa. Dialdehyde pineapple starch-based plastic exhibited the highest tensile strength (~ 42&#xa0;MPa), which may be associated with its higher apparent amylose content and structural characteristics. XRD indicated predominantly amorphous structures for the DAS-based plastics, while SEM showed generally more homogeneous fracture morphologies than native-starch plastics, except for D-sago, which retained heterogeneous features. For the pineapple-derived system, ATR-FTIR analysis after hot compression showed weakening of the aldehyde-related band, providing supportive evidence for chemical interactions during molding consistent with thermoset-like network formation. The modified plastics also demonstrated reduced water absorption and generally increased hydrophobicity with water contact angles of ~ 66–69° for most samples, except D-sago (~ 48°). All DAS materials showed biodegradation under controlled aerobic composting conditions, although at a slower rate than the native-starch plastics over the 60-day test period. These findings indicate that dialdehyde starch, particularly from pineapple stem waste, is a promising precursor for stronger and more water-resistant starch-based materials under the conditions studied, while emphasizing the importance of balancing mechanical performance and recovery yield across different botanical starch sources.</p>

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Botanical origin influences the performance of thermosetting plastics derived from dialdehyde starches including pineapple stem starch

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年7月31日

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  • Wasan Tessanan,
  • Rawinun Sutthikitivorakul,
  • Jitti Niyompanich,
  • Meyphong Leang,
  • Taweechai Amornsakchai

摘要

Starch-based plastics offer a sustainable alternative to conventional polymers, but their practical use remains limited due to low mechanical strength and high moisture sensitivity. This study presents a systematic comparison of thermosetting plastics derived from dialdehyde starches (DAS) prepared from six botanical sources, rice, sago, cassava, corn, potato, and pineapple, with particular emphasis on the valorization of pineapple stem starch, an abundant agricultural waste. All starches were converted into dialdehyde starch via aqueous periodic acid oxidation, aldehyde contents of approximately 30–34%. The DAS powders were plasticized with 40 wt% glycerol and processed by hot compression molding to yield thermoset-like materials, likely through acetal and hemiacetal linkages. Compared with thermoplastic starches fabricated from native starch (modulus ≈ 56–64 MPa; tensile strength ≈ 2–4 MPa), the DAS-based thermosets exhibited markedly improved mechanical properties, with modulus values of ~ 1200–1900 MPa and tensile strengths of ~ 19–42 MPa. Dialdehyde pineapple starch-based plastic exhibited the highest tensile strength (~ 42 MPa), which may be associated with its higher apparent amylose content and structural characteristics. XRD indicated predominantly amorphous structures for the DAS-based plastics, while SEM showed generally more homogeneous fracture morphologies than native-starch plastics, except for D-sago, which retained heterogeneous features. For the pineapple-derived system, ATR-FTIR analysis after hot compression showed weakening of the aldehyde-related band, providing supportive evidence for chemical interactions during molding consistent with thermoset-like network formation. The modified plastics also demonstrated reduced water absorption and generally increased hydrophobicity with water contact angles of ~ 66–69° for most samples, except D-sago (~ 48°). All DAS materials showed biodegradation under controlled aerobic composting conditions, although at a slower rate than the native-starch plastics over the 60-day test period. These findings indicate that dialdehyde starch, particularly from pineapple stem waste, is a promising precursor for stronger and more water-resistant starch-based materials under the conditions studied, while emphasizing the importance of balancing mechanical performance and recovery yield across different botanical starch sources.