Flexible crosslinking of polyurethane using grafted poly(dimethylsiloxane) with Epichlorohydrin and Bisphenol A end groups and its impact on the mechanical properties and low-temperature flexibility

Poly(dimethylsiloxane) (PDMS) was grafted onto polyurethane (PU), and Epichlorohydrin and Bisphenol A were attached to the free ends of PDMS groups and used to link the grafted PDMS to thereby introduce flexible crosslinks between the PU chains. The flexible crosslinks enhanced the crosslink density and solution viscosity of PU but did not change the melting and crystallization behaviors of the soft segments of PU. In particular, the flexible PDMS crosslinks increased the maximum tensile stress by up to 300% and the maximum tensile strain up to 180%. The shape recovery capability at 10°C and the shape retention capability at −25°C were maintained above 90% with the flexible crosslinking. Grafted PDMS moderately improved the low-temperature flexibility of PU due to its flexibility at low temperature. The flexible crosslinks of grafted PDMS successfully improved the tensile strength, shape recovery, and low-temperature flexibility of the PU.

Effect of Heat Aging on Properties and Structure of SBS Modified Bitumen Waterproof Membrane

The properties of SBS modified bitumen waterproof membrane (SMBM) will deteriorate under the action of heat. In this paper, SBS modified bitumen (SMB) and SMBM were aged at 80 °C for different times (0,10,20,30,40 days). The low temperature flexibility, softening point, viscosity and mass changes ratio of SMB and mechanical properties of SMBM before and after aging were tested, the microstructure and chemical structure of SMB were investigated by fluorescence microscope (FM) and Fourier transform infrared spectroscopy (FTIR). The results show that the low temperature flexibility, softening point and viscosity of SMB decrease significantly at the initial stage of heat aging (10 days), especially the influence of heat aging on the low temperature flexibility and viscosity of SMB is more obvious, and their properties degradation rate slowdown in the later stage of aging. The mass changes ratio of SMB first decreases and then increases with aging time. FM shows that the network crosslinking structure of SMB is destroyed gradually with the extension of aging time. The network crosslinking structure disappears after 40 days of heat aging. FTIR shows that carbonyl and sulfoxide compounds are increasing after aging, more carbonyl compounds than sulfoxide compounds are formed after aging for 10 days, and the degradation rate of SBS decreases. The maximum tension of SMBM first increases and then decreases, the elongation at maximum tension decreases with aging time.

Effect of Chemical Corrosion on Properties of SBS Modified Bitumen for Waterproofing Membranes

SBS modified bitumen membrane used in underground engineering and coastal buildings would be corroded by chemical media, which greatly influenced the service life of waterproofing membranes. In this paper, SBS modified bitumen (MB), SBS modified bitumen with stone powder (MBS) and SBS modified bitumen with talc powder (MBT) were corroded by acidic, alkaline, and saline solutions for different time to evaluated the effect of chemical corrosion on the properties of SBS modified bitumen waterproofing membrane. The mass change ratio, low temperature flexibility, softening point and viscosity of SBS modified bitumen were investigated, and Fourier infrared spectroscopy (FTIR) was used to analyze the chemical structural changes of SBS modified bitumen after corrosion. The results showed that the mass of SBS modified bitumen decreased, the low temperature performance decreased, and the softening point increased after corrosion by chemical solutions. The influence of acidic and saline solution was more serious on SBS modified bitumen with fillers, and the properties of MBS has greatest degradation in acidic solution compared with MB and MBT. In alkaline solution, the properties degradation of MBT and MBS was less than that of MB, which indicated that filler could inhibit the alkaline corrosion of SBS modified bitumen. FTIR showed that C=C decreased more in acidic solution, while C=O and S=O of SBS modified bitumen increased significantly after alkaline solution corrosion, which indicated that acidic solution corrosion easily caused SBS degradation, while alkaline solution corrosion was easy to oxidize SBS and bitumen.

Effect of Non-Sulfur Stabilizer on Performance of SBS Modified Bitumen

Based on the reason that SBS modified bitumen (SMB) with sulfur stabilizer is easy to degrade during aging, a novel non-sulfur stabilizer, P-benzoquinone oxime (GMF), was used to modify SMB. The effects of GMF and sulfur stabilizer on the thermal storage stability, low-temperature performance and aging resistance of SMB were investigated. The results indicate that GMF is more beneficial to improve the thermal storage stability, the low temperature flexibility and softening point of SMB than that of sulfur. And GMF can restrain the degradation of the low temperature flexibility of SMB after thermal aging as compared with sulfur. Fourier transform infrared spectroscopy indicates that the aging growth index of GMF/SBS modified bitumen is 33.5% lower than that of sulfur/SBS modified bitumen after aging. Fluorescence microscope proves that the addition of GMF can prevent the destruction of cross-linking network structure of SBS in bitumen during aging process, which also demonstrates that GMF can improve the aging resistance of SMB. Therefore, GMF can be more suitable as a stabilizer for SMB.

Conducting Silicone-Based Polymers and Their Application

Over the past two decades, both fundamental and applied research in conducting polymers have grown rapidly. Conducting polymers (CPs) are unique due to their ease of synthesis, environmental stability, and simple doping/dedoping chemistry. Electrically conductive silicone polymers are the current state-of-the-art for, e.g., optoelectronic materials. The combination of inorganic elements and organic polymers leads to a highly electrically conductive composite with improved thermal stability. Silicone-based materials have a set of extremely interesting properties, i.e., very low surface energy, excellent gas and moisture permeability, good heat stability, low-temperature flexibility, and biocompatibility. The most effective parameters constructing the physical properties of CPs are conjugation length, degree of crystallinity, and intra- and inter-chain interactions. Conducting polymers, owing to their ease of synthesis, remarkable environmental stability, and high conductivity in the doped form, have remained thoroughly studied due to their varied applications in fields like biological activity, drug release systems, rechargeable batteries, and sensors. For this reason, this review provides an overview of organosilicon polymers that have been reported over the past two decades.

Recent Advances in Functional Polyurethane and Its Application in Leather Manufacture: A Review

Over last few years, polyurethane (PU) has been applied in a number of areas because of its remarkable features, such as excellent mechanical strength, good abrasion resistance, toughness, low temperature flexibility, etc. More specifically, PU can be easily “tailor made” to meet specific demands. This structure–property relationship endows great potential for use in wider applications. With the improvement of living standards, ordinary polyurethane products cannot meet people’s growing needs for comfort, quality, and novelty. This has recently drawn enormous commercial and academic attention to the development of functional polyurethane. Among the major applications, PU is one of the prominent retanning agents and coating materials in leather manufacturing. This review gives a summary of academic study in the field of functional PU as well as its recent application in leather manufacture.

Control of the water compatibility and shape recovery of polyurethane using the graft polymerization of poly(ethylene glycol) methyl ether acrylate

Graft polymerization of poly(ethylene glycol) methyl ether acrylate (PEGA) onto polyurethane (PU) was conducted to improve its water compatibility, tensile mechanical strength, shape memory, and low-temperature flexibility properties, as well as to control its water vapor permeability (WVP). Control PUs containing free poly(PEGA) were also prepared to compare with the poly(PEGA)-grafted PUs. The water compatibility of PU notably improved due to the grafting of poly(PEGA) based on water contact angle results. The soft segment melting temperature and glass transition temperature were not changed with the increase in the PEGA content. The tensile strength of PU sharply increased due to the grafting of poly(PEGA), whereas the free poly(PEGA) in the control PUs did not cause a similar increase. The maximum strain of PU was not affected by the grafting of poly(PEGA). The shape recovery at 0°C significantly increased compared with the unmodified PU. The low-temperature flexibility of PU improved, and the WVP through the PU membrane was reduced by the grafting of poly(PEGA) onto PU.

Effect of FCC Slurry on Performance of SBS Modified Bitumen

Fluid catalytic cracking (FCC) slurry is a by-product of petrochemical industry rich in aromatics. In this paper, the effect of FCC slurry on the physical properties of SBS modified bitumen was investigated by softening point, penetration, ductility and low temperature flexibility test. The influence of FCC slurry on the compatibility of SBS modified bitumen was evaluated by fluorescence microscope and segregation test. The results show that FCC slurry improves the softening point, penetration, ductility and low temperature flexibility of SBS modified bitumen. Fluorescence microscope showed that FCC slurry promotes the dispersion of SBS in bitumen, which is conducive to the formation of network crosslinking structure of SBS modified bitumen. The segregation test indicated that the compatibility of SBS with bitumen was improved with the content of FCC slurry increasing.