Polyolefins (POs) are considered a promising candidate for photovoltaic cell encapsulation due to their high volume resistivity, low water-vapor permeability, and outstanding outdoor stability. However, POs without functionalization have a low rate of cross-linking, which significantly slows the solar cell encapsulation process. Herein, we describe the use of a polymer product-engineering approach in which reactive pendent vinyl groups are controllably incorporated in PO polymer chains to accelerate their cross-linking reactions. The POs having limited vinyl functionalities of 0.02–0.37 mol % were synthesized via the copolymerization of ethylene, 1-octene, and vinylnorbornene or 1,9-decadiene at different monomer concentrations. The vinyl groups in the POs readily react with curing agents, increasing cross-linking rates by 14-fold up to 179.7 Pa·s^–1, as measured by the enhancement of the storage modulus (G′). The maximum G′ value representing the melt strength was also increased from 11.3 to 69.0 kPa due to the high curing degree in the POs. The use of a curing agent could be reduced by 50%, and no curing coagent was required in the PO curing process. The vinyl-functionalized POs had a light transmittance of 91%, a good volume resistivity of 7.05 × 10¹⁶ Ω·m, a low water-vapor permeability of 2.31 × 10^–12 g·m·m^–2·s^–1·Pa^–1, and an improved mechanical strength after curing. The damp-heat and UV aging had little effect on their light transmittance. Our approach of synthesizing functional POs with pendent vinyl groups thus promises the development of new high-performance polymer materials for photovoltaic cell encapsulation.

中文翻译：

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乙烯基官能化聚烯烃，用于快速光伏电池封装

聚烯烃（POs）由于具有高体积电阻率，低水蒸气渗透性和出色的室外稳定性，因此被认为是光伏电池封装的有前途的候选材料。但是，没有功能化的PO的交联速率低，这会大大减慢太阳能电池的封装过程。在这里，我们描述了一种聚合物产品工程方法的使用，其中反应性侧基乙烯基可控地掺入PO聚合物链中以加速其交联反应。通过乙烯，1-辛烯和乙烯基降冰片烯或1,9-癸二烯在不同单体浓度下的共聚反应，可以合成出乙烯基官能度为0.02-0.37 mol％的PO。PO中的乙烯基易于与固化剂反应，使交联速率提高14倍，最高达到179.7 Pa·s^–1，通过提高储能模量（G'）来衡量。由于POs的高固化度，代表熔体强度的最大G'值也从11.3 kPa增加到69.0 kPa。可以将固化剂的使用减少50％，并且在PO固化过程中不需要固化助剂。乙烯基官能化的PO具有91％的透光率，7.05×10的良好的体积电阻率¹⁶ Ω·m时，低水蒸汽渗透性的2.31×10 ^-12克·米·米^-2 ·秒^-1 · Pa ^–1，并提高了固化后的机械强度。湿热和紫外线老化对其透光率几乎没有影响。因此，我们合成具有悬垂乙烯基的功能性PO的方法有望开发出用于光伏电池封装的新型高性能聚合物材料。