Effect of chemical treatments on properties of injection molded Nypa fruticans fiber reinforced polypropylene composite.

The rise in environmental awareness prompted consideration of environment friendly materials. Natural fiber, on the contrary, has a structure that allows it to absorb moisture attributable to its hydrophilicity, which hinders its wide application and leads to poor interfacial bonding with the polymer matrix. Therefore, fiber surface modification is inevitable, which is usually based on using the functional group of some chemicals to replace the hydrophilic hydroxyl group to make it more moisture resistant and ameliorate the boding between fiber and polymer matrix. In this study, injection molded nypa fiber reinforced polypropylene composites were fabricated. Three different chemical modification i.e., mercerization, H2O2 treatment, maleic anhydride polypropylene (MAPP) compatibilizer, were employed. Other parameters on which the properties of the composite depend, i.e., fiber volume (30%), manufacturing process, etc. were kept the same. Field emission scanning electron microscopic (FE-SEM) images were also investigated to verify the result of experiments. Moisture resistance of the composite was also evaluated. The tensile and flexural properties of treated composite were significantly enhanced than the untreated one. The maximum strength was obtained for MAPP treated composite. The chemical treatment has a less impact on the impact strength of the composite. Better moisture resistance was observed for treated fiber composites. This study provides the insight of using chemical treatment for better adhesion between the fiber and the polymer.

Differences in reported linguistic thermal sensation between Bangla and Japanese speakers.

BACKGROUND: Thermal sensation is a fundamental variable used to determine thermal comfort and is most frequently evaluated through the use of subjective reports in the field of environmental physiology. However, there has been little study of the relationship between the semantics of the words used to describe thermal sensation and the climatic background. The present study investigates the linguistic differences in thermal reports from native speakers of Bangla and Japanese. METHODS: A total of 1141 university students (932 in Bangladesh and 209 in Japan) responded to a questionnaire survey consisting of 20 questions. Group differences between Bangladeshi and Japanese respondents were then tested with a chi-square test in a crosstab analysis using SPSS (version 21). RESULTS: For the Bangla-speaking respondents, the closest feeling of thermal comfort was "neutral" (66.6%) followed by "slightly cool" (10.2%), "slightly cold" (6.0%), "slightly hot" (4.1%), and "cold" (3.8%). For the Japanese respondents, the closest feeling of thermal comfort was "cool" (38.3%) followed by "slightly cool" (20.4%), "neutral" (14.6%), "slightly warm" (13.1%), and "warm" (10.7%). Of the Bangladeshi respondents, 37.7% reported that they were sensitive to cold weather and 18.1% reported that they were sensitive to hot weather. Of the Japanese respondents, 20.6% reported that they were sensitive to cold weather and 29.2% reported that they were sensitive to hot weather. Of the Bangladeshi respondents, 51.4% chose "higher than 29 °C" as hot weather and 38.7% of the Japanese respondents chose "higher than 32 °C" as hot weather. In the case of cold weather, 43.1% of the Bangladeshi respondents selected "lower than 15 °C" as cold weather and 53.4% of the Japanese respondents selected "lower than 10 °C" as cold weather. CONCLUSIONS: Most of the Bangla-speaking respondents chose "neutral" as the most comfortable temperature, and most of the Japanese respondents chose "cool." Most of the Bangladeshi respondents reported that they were sensitive to "cold temperatures," but most of the Japanese respondents reported that they were sensitive to "hot temperatures."

Cold-induced vasodilation comparison between Bangladeshi and Japanese natives.

BACKGROUND: The human thermoregulation system responds to changes in environmental temperature, so humans can self-adapt to a wide range of climates. People from tropical and temperate areas have different cold tolerance. This study compared the tolerance of Bangladeshi (tropical) and Japanese (temperate) people to local cold exposure on cold-induced vasodilation (CIVD). METHODS: Eight Bangladeshi males (now residing in Japan) and 14 Japanese males (residing in Japan) participated in this study. All are sedentary, regular university students. The Bangladeshi subject's duration of stay in Japan was 2.50 ± 2.52 years. The subject's left hand middle finger was immersed in 5 °C water for 20 min to assess their CIVD response (the experiment was conducted in an artificial climate chamber controlled at 25 °C with 50% RH). RESULTS: Compared with the Bangladeshi (BD) group, the Japanese (JP) group displayed some differences. There were significant differences between the BD and JP groups in temperature before immersion (TBI), which were 33.04 ± 1.98 and 34.62 ± 0.94 °C, and time of temperature rise (TTR), which were 5.35 ± 0.82 and 3.72 ± 0.68 min, respectively. There was also a significant difference in the time of sensation rise (TSR) of 8.69 ± 6.49 and 3.26 ± 0.97 min between the BD and JP groups, respectively (P < 0.05). Moreover, the JP group showed a quick TTR after finishing immersion. CONCLUSIONS: The Japanese group (temperate) has a higher tolerance to local cold exposure than the Bangladeshi group (tropical) evaluated by the CIVD test.