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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 2~3°C. 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.

In this paper, maleic anhydride (MA) was grafted onto methyl cellulose (MC) and then reacted with acrylic acid to synthesize a high gel strength and fast water absorption resin (AA-co-MC-g-MA) by UV polymerization. The reaction conditions of maleylated methylcellulose (MC-g-MA) were investigated, including the ratio of MC to MA, reaction time and catalyst amount. In addition, the reaction conditions for the synthesis of super absorbent resin were as follows: the amount of MC-g-MA, the degree of substitution of MC-g-MA, polymerization time, and the amount of initiator. Under optimal conditions, the maximum water absorption volume of synthetic resin was 2116 g/g, and the maximum salt absorption rate was 139 g/g. The water absorption resin prepared this time had high water absorption, water retention, excellent pH sensitivity, etc. It was hoped that it will have a good application prospect in the field of industrial production and agriculture in the future.

In this paper, the effects of coupling agent and lignin extracted from waste cotton stalks in Xinjiang on thermal-oxygen 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.

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.

This paper describes the separation of oxidation resistant components from the seeds of pomegranate (PSA), grape (GSE) and sea buckthorn (SSE). The anti-oxidation properties of the resultant extracts, used as the natural anti-oxidants for polypropylene (PP), were compared with Irganox1010. The effects of these natural antioxidants on the antioxidant levels of PP samples were estimated by thermal oxidative aging and micromixed rheology, OIT, XRD, SEM, TEM and mechanical properties tests of samples before and after aging. The results show that adding PSA, GSE and SSE can obviously increase the mechanical properties of PP. In addition, the molding stability of polypropylene raw material is prolonged and improved. Moreover, the mechanical properties of the PP samples after 240 h of thermal oxidative aging indicates that, the best results, closest to the anti-oxidation ability of Irganox1010, can be obtained when the additive amount is 0.5% (wt%) for PSE or 0.7% (wt%) for GSE.

In this paper, ionic liquid method and ultrasound-assisted ionic liquid method were used to extract lignin and the effects of various factors on the extraction of lignin were investigated. The properties and antioxidant properties of lignin were studied. The lignin extraction rates of the two methods were 93.60% and 94.01%, respectively. On this basis, the oxidation resistance and stability of lignin in polypropylene were studied, and the added value of lignin was increased. It was shown that the lignin extracted by two different methods had a certain antioxidant effect, and the ultrasonic assisted ionic liquid lignin had the best antioxidant effect. [ABSTRACT FROM AUTHOR]

The weathering performance of polypropylene (PP) was studied in an artificial accelerated weathering chamber of 340 nm ultraviolet light and natural conditions in Turpan, China. This work aimed to provide a method for calculating the aging failure of PP under natural conditions by the means of artificial accelerated aging. SEM showed that large crack widths of approximately 1.25 µm and 1.63 µm appealed on the PP surface after 15 days artificial accelerated aging and 150 days natural aging, respectively. XPS data revealed that the number of C-O and C=O bonds on the PP surface were generally the same after artificial accelerated aging and natural aging of PP for 3 and 30 days, 6 and 60 days, or 9 and 90 days, respectively. Moreover, the data of mechanical properties and capillary rheology also exhibited similar results. It was concluded that the aging rate of artificial accelerated aging was 10 times faster than that of natural aging in Turpan. [ABSTRACT FROM AUTHOR]