Synthesis and properties of biodegradable hydrogels based on cross-linked natural rubber and cassava starch

Abstract

A series of interpenetrating polymer network (IPN) hydrogels based on cross-linked natural rubber (XNR) and cassava starch (CSt) as biodegradable membrane material were synthesized via free radical polymerization in latex state using N, N′-methylene bisacrylamide (MBA) and maleic acid as cross-linkers. The IPN XNR/CSt hydrogels were confirmed and characterized by infrared spectroscopy, thermal analysis, and X-ray diffraction. The results showed that with increasing MBA content from 1.0 to 2.5 phr, cross-link density and gel fraction of XNR increased from 0.80 to 0.90 mol M−3 and from 19.7% to 30.5%, respectively. The gel fraction and tensile strength of the IPN XNR/CSt hydrogels also gradually increased as a function of MBA content but the water swelling and elongation at break decreased slightly. The IPN XNR/CSt containing 1.0 phr MBA displayed the highest water swelling of 82%. The weight retentions of IPN XNR/CSt hydrogels after soil degradations for 90 days increased from 48% to 56% with increasing MBA from 1.0 phr to 2.5 phr. The IPN XNR/CSt exhibited not only a good biodegradation but also high mechanical strength and flexibility. Also, the IPN XNR/CSt could be a promising candidate as a biodegradable membrane for longer released fertilizer application.

Preparation of environment‐friendly hydrophilic rubber from natural rubber grafted with sodium acrylate by reactive melt mixing

“…These holes were probably the channels that the water molecules diffused through into the internal XNR‐g‐NaAA sheet. [ 64 ] Moreover, the water swelling of XNR‐g‐NaAA was found to be 13%, while that of XNR was still unchanged (0%). Thus, the wettability and hydrophilicity of NR were achieved by grafting with NaAA, and the interactions between NR‐g‐NaAA and water molecules or other hydrophilic materials can be increased and potentially applied in hydrophilic fields, such as a control‐release membrane, adhesive, and so on.…”

Biodegradability of bio‐based and synthetic hydrogels as sustainable soil amendments: A review

“…As seen in Table 1, five studies synthesized hydrogels using starch as a backbone material. 25,28,33,34,60 The highest degradation rate was observed by Riyajan et al, 34 who reported 80% biodegradation of their hydrogel in 30 days using the soil burial method. Sahoo and Rana 60 observed that adding starch alone or poly (ethyl methacrylate) in alluvial soil led to lower biodegradation of about 38% and 20%, respectively, after 12 months of incubation using the soil burial method.…”

“…31 In the soil burial test, the extent of biodegradation is determined by measuring the weight loss in the hydrogel, which is assumed to represent the percentage of biodegradation in soil. 28,[32][33][34] In the case of the supernatant incubation method, the extent of biodegradation is determined by either weight loss, 31,35 through structural, morphological examination using a scanning electron microscope, 26,36 or through quantifying the CO 2 mineralization using a gas chromatograph or other measuring equipment. 35,37,38 While the soil burial and weight loss method are commonly used in literature, this method has some limitations.…”

“…Roy et al 61 hypothesized that excessive crosslinking reduced the volume of the polymer networks, which limited microbial access leading to lower biodegradation rates (Vudjung and Saengsuwan). 33 The practical implication of their results is that optimized crosslinking should be a key variable during hydrogel synthesis, as excessive crosslinking slows down biodegradation 33,61 and limits the swelling capacity of hydrogels. 62 Tanan et al 28 synthesized a biodegradable semi-interpenetrating polymer network (semi-IPN) hydrogel based on cassava starch.…”

Chitosan and Natural Rubber Latex Biocomposite Prepared by Incorporating Negatively Charged Chitosan Dispersion

“…However, the products from NRL show some weaknesses such as low modulus, barrier properties and electrical properties that affect the quality of the natural rubber (NR) products. Consequently, many attempts have been made to use a reinforcing filler such as graphene oxide [ 5 ], multiwalled carbon nanotube [ 6 ], organoclay [ 7 , 8 ], carbon black [ 9 ], silica [ 10 ], cassava starch [ 11 ], and carbon fiber [ 12 ], to improve NR properties. The incorporation of bio-fillers from renewable resources into NRL could result in new biocomposites with enhanced features and biodegradability, so it is of interest to study the possibility of using chitosan (CT) as a reinforcing filler for NRL.…”