The
glassy polymer of polystyrene (PS) enjoys a good reputation as a promising
optical material; however, the inherent brittleness hinders its further
applications. Conventional toughening methods are realized based on
the premise of a sacrifice in transparency and stiffness. In this
work, we found an unprecedented strategy to address these obstacles
by combining extensional stress-induced ductility and suppressing
physical aging. PS-based film with a high stiffness, long-term ductility,
and excellent transparency is achieved by introducing a styrene–butadiene
block copolymer into the PS matrix and subsequently annealing stretched.
A nanofibrillar structure of the polybutadiene (PB) phase is formulated
surrounded by a PS matrix, and thus, the elongation at break enhances
from 3.1% up to 86.8%, accompanying the yield strength enhanced from
25.5 to 62.2 MPa. More significantly, compared with neat PS, these
films survive from physical aging and persistent ductility over time.
The morphology deformation induced by stress makes an obvious contribution
to the improvement of transparency. Investigating the dynamics of
chain segments indicates that the incorporation of the copolymer can
restrict rearrangement and local relaxation to the PS chain. This
work could pave a potential route toward high-performance PS and might
be transferable to other glassy polymers with a fragile character.
Nystagmus information is an essential basis for diagnosing benign paroxysmal positional vertigo (BPPV), and nystagmus recorders are a crucial way to obtain nystagmus information. We designed a new wireless video nystagmus recorder, which uses the OV4689 sensor to collect the nystagmus video, encodes it on the RK3399 core control board, and sends it to the host computer through the 5GHz WiFi module. Compared with the current nystagmus recorder, it has the advantages of low price, convenient operation, and high frame rate. This paper uses a novel semantic segmentation network based on the Yolov5 target detection network and the improved Deplabv3+ segmentation module to perform real-time pupil segmentation on the collected video. Based on the segmentation results, we use ellipse fitting to extract the boundary and center of the pupil for drawing the pupil activity trajectory. Compared with the existing pupil tracking method, the method divides the pupil area faster and with higher precision, ensuring the pupil center positioning accuracy. The technique can effectively assist doctors in the diagnosis of BPPV.
Electrical conductive of polystyrene (PS)/poly(butyl methacrylate) (PBMA)/carbon black (CB) and PS/poly (cyclohexyl methacrylate) (PChMA)/CB ternary composite films with different polymer blend ratios are prepared through solution casting. The percolation thresholds (ϕ
c
) of all the composite films before and after thermal annealing have been determined through the McLachlan GEM equation. Moreover, the PS/poly (methyl methacrylate) (PMMA)/CB and PS/poly (ethyl methacrylate) (PEMA)/CB films obtained from the same method while only considering conductivity after thermal annealing as well in this work for comparison. Though the CB particles are revealed to be located at only one polymer phase of all four different polymer blends, with compatibility between polymer blends increasing, the ternary composite films show different ϕ
c
behaviors by changing polymer blend ratios. In PS/PChMA/CB case, the phase separation between PChMA and PS cannot be observed under scanning electron microscope (SEM). After thermal annealing, all the ϕ
c
of PS/PChMA/CB films with different PS/PChMA ratios almost show a linear behavior instead of the double percolation behavior with PChMA content increasing. Suppose both ϕ
c
of binary systems (polymer A/filler and polymer B/filler) is determined. In that case, a linear behavior relationship between the ϕ
c
of the ternary composites (A + B + fillers) with the ratio of two polymers can be revealed when polymer A and B are miscible.
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