The influence of interphase on the tensile property of composite is examined in the present study. For this, fabrication of composite (FOC) is carried out using natural fibers: bamboo fiber and jute fiber and polyester resin as per the hand layup technique. The fibers are arranged in a longitudinal direction with varying the volume fraction of fiber (v_f). The tensile testing of fibers, polyester and composites are held on the universal testing machine (UTM) and evaluated experimental tensile properties: tensile strength (TS) and elastic modulus (E). The mathematical models are proposed to measure the influence of interphase on the longitudinal elastic modulus of composite (E_cl) for longitudinally placed unidirectional fiber-reinforced polymer composites (LUDFPC) with varying interphase volume fraction (v_i). The different interphase property variations: linear variation, hyperbolic variation, parabolic variation, powerlaw variation and exponential are considered in the modeling of composite and measure its effect on E_cl. The comparative study of proposed models with other researchers’ models is carried out. The validation of developed models is carried out using other researchers’ experimental data. The present study signifies the important outcome as v_i should be around 15 % to 20 % of v_f to predict E_cl; Parabolic variation is recommended for the prediction of E_cl.

本研究考察了界面对复合材料拉伸性能的影响。为此，复合材料 (FOC) 的制造是使用天然纤维：竹纤维和黄麻纤维以及聚酯树脂，按照手糊技术进行的。纤维以不同的纤维体积分数 (v _f )沿纵向排列。纤维、聚酯和复合材料的拉伸测试在万能试验机 (UTM) 上进行，并评估实验拉伸性能：拉伸强度 (TS) 和弹性模量 (E)。提出了数学模型来衡量界面对复合材料纵向弹性模量的影响（E _cl）为纵向放置单向纤维增强的聚合物复合材料（LUDFPC）与相间体积分数变化（V_我）。在复合材料的建模中考虑了不同的相间特性变化：线性变化、双曲线变化、抛物线变化、幂律变化和指数变化，并测量其对 E _{cl 的影响}。对提出的模型与其他研究人员的模型进行了比较研究。开发模型的验证是使用其他研究人员的实验数据进行的。本研究表明了重要的结果，因为 v _i应该是 v _{f 的}15% 到 20% 左右才能预测 E _cl；推荐抛物线变化用于预测 E _cl.