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Role of different lignin systems in polymers: mechanical properties and thermal stability

Hasan Gvlmira, Musajan Dilhumar, Hou Gong-bo, He Mingyu, Li Ying, Yimit Mamatjan

Polish Journal of Chemical Technology

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2020

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Vol. 22, nr 4

10--16

EN

Lignin was used to study the mechanical properties and thermal stability of polymers. The lignin was blended with three kinds of polymers, and the addition of lignin was 0.5 wt%. Under the condition of thermal oxidation, the thermal stability of lignin/polymer samples varies with the structure of lignin. The effects of lignin on the mechanical properties and thermal stability of the polymers were investigated by oxidation induction time (OIT), rheological properties, mechanical properties and differential scanning calorimetry (DSC). The results show that the effect of lignin on the thermal properties of polymer samples is 2~3oC. It can be inferred that lignin can effectively improve the interaction between polymer molecular chain segments, and improve the crystallization rate and rigidity to a certain extent, so it can be seen that lignin has good compatibility and thermal stability.

2

Free radical scavenging ability of sodium lignosulfonate and its application in food grade polypropylene

Musajian Dilhumar, Hasan Gvlmira, He Mingyu, Yimit Mamatjan

Polish Journal of Chemical Technology

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2020

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Vol. 22, nr 2

56--66

EN

Sodium lignosulfonate (SL) was prepared from waste of cotton lignin (CL) through hydrothermal reaction method. Orthogonal experiment was designed with value of OIT as objective function. Polypropylene (PP) is a polymer produced by the addition polymerization of propylene. It is a white waxy material with a transparent and light appearance, which is widely used in food and pharmaceutical packaging. The results of GPC and TG analysis revealed that SL has stable thermal properties, which means that SL has the potential to be an antioxidant for PP materials. In addition, the scavenging effects of CL and SL were studied. The obtained results exhibited that the SL can obviously increase the scavenging effect on free radicals and it is a kind of new synthetic antioxidant with antioxidant property, which could effectively delay the oxidation of PP. Subsequent rheological experiments proved that the SL/PP sample can improve the heat-resistant oxygen performance of PP under the thermal oxygen shearing environment. Combined with the effect of SL on the mechanical properties of PP before aging, SL has a stabilizing effect on PP thermal oxygen aging.

3

Effects of coupling agent on antioxidant properties and structure of PP/ cotton stalk lignin composites

He Mingyu, Musajian Dilhumar, Hasan Gvlmira, Hou, Gongbo, Yimit Mamatjan

Polish Journal of Chemical Technology

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2020

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Vol. 22, nr 2

78--85

EN

In this paper, the effects of coupling agent and lignin extracted from waste cotton stalks in Xinjiang on thermaloxygen aging properties of polypropylene (PP) composites were studied. The melt index test and indoor thermal oxygen aging test was carried out on the samples treated with coupling agent. The mechanical properties, surface micromorphology, rheological properties and element composition of the materials before and after 30 days of aging were studied. The results showed that the titanate coupling agent was the best for improving the melt index and mechanical properties of PP/cotton stalk lignin composites. After the 30-day thermal oxygen aging test, the samples with 2% lignin had the best impact strength and retention rate of fracture elongation, reaching 68.9% and 77.3% respectively. The sample with 3% lignin content had the smoothen surface, no crack appeared. After aging, the increase of C=O was the least, and the crystal peak area decreased less.